JP4284911B2 - Element transfer method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an element separation method and an element transfer method, and more particularly to an element separation method and an element transfer method suitable for fine element separation and transfer.
[0002]
[Prior art]
Currently, electronic devices and the like are widely used that are configured by arranging a large number of fine elements, electronic components, electronic devices, and electronic components in which they are embedded in an insulator such as plastic. .
[0003]
For example, a pixel of an active matrix driving light emitting diode (LED) display is composed of an active matrix driving element (driving chip) and LED elements of respective colors. The drive chip and the LED element are arranged on the same substrate, but when the thickness of the drive element is thick, the light emission from the LED element cannot be used efficiently, so the drive chip manufactured from the bulk silicon substrate Needs to be thinned to about several tens of μm in accordance with the thickness of the LED element. Since the driving chip has a substrate thickness of about 1 mm in the wafer process step, it is necessary to reduce the thickness and to pelletize the pixel chip size to 1 mm or less. In order to pelletize, conventionally, as shown in FIG. 20, after forming a separation groove 102 slightly deeper than a desired finished thickness in the chip separation region of the silicon substrate 101 after the process step, the silicon substrate 101 is bonded to the adhesive tape 103. 21, a so-called DBG process is performed in which chip division is performed by grinding the silicon substrate 101 to a desired thickness from the back side of the silicon substrate 101 as shown in FIG.
[0004]
[Problems to be solved by the invention]
However, in this method, when grinding proceeds to the bottom of the separation groove, the silicon substrate is subjected to stress that is pushed in the direction of the main surface, and there is a problem that chip displacement occurs depending on the adhesive property of the adhesive tape. Furthermore, there is a problem that the chip pitch is shifted due to the expansion and contraction of the base film of the adhesive tape, and the transfer of the chip after separation cannot be performed accurately. In addition, when the element is miniaturized, when the grinding reaches a groove, the adhesive force of the adhesive tape cannot hold the chip reliably due to insufficient adhesive force, and the chip peels off or falls down There is a problem of end.
[0005]
In recent years, with the demand for lowering the cost of semiconductor devices by improving their characteristics and yield, there is an urgent need to increase the density during element formation.
[0006]
For example, in the case of a thin film transistor (TFT) liquid crystal, an element composed of a transistor, a capacitor, and the like is required to control the luminance of one pixel composed of LEDs of three colors R, G, and B. Currently, for large liquid crystal elements and the like, these drive circuits are built on a glass substrate. However, due to the increase in the area of the substrate, the variation in characteristics within the surface becomes large and is becoming unacceptable. Therefore, as represented by MCM (Multi-Chip Module), which consists of multiple semiconductor chips in one package, the drive circuit is fabricated on another substrate such as a silicon substrate and then expanded on the desired substrate. Transcription technology is attracting attention.
[0007]
However, in the case of an element having a size of several hundreds μm □ such as a TFT element, in the element isolation method by dicing using a conventional diamond saw blade, the thickness of the diamond saw blade is, for example, about 30 μm to 40 μm. Must be set larger. That is, there is a problem that it is difficult to increase the density of the elements when forming the elements in order to secure a cutting allowance in dicing.
[0008]
Therefore, the present invention has been made in view of the above-described conventional situation, and an element separation method capable of accurately and reliably separating and further transferring an element formed on a substrate, and It is an object to provide a transfer method.
[0009]
Another object of the present invention is to provide an element isolation method and a transfer method that can provide a semiconductor device at low cost by enabling high-density formation of elements.
[0010]
[Means for Solving the Problems]
Achieve the above objectives Rumo The element separation method is an element separation method for separating a plurality of elements formed on an element formation substrate, and grinding the main surface of the element formation substrate on the side opposite to the element formation side, the element It comprises a grinding step for thinning the formation substrate, and a separation step for separating the elements by etching a plurality of elements of the element formation substrate from the ground surface on which grinding has been performed.
[0011]
As above Raw In the element isolation method, the element formation substrate is thinned and then element isolation is performed by etching. Therefore, the element isolation region at the time of element isolation is, for example, about 5 μm, which is significantly larger than the case of element isolation by conventional dicing. Becomes narrower. As such etching, for example, plasma dry etching using a chlorine-based gas is suitable.
[0012]
In this element isolation method, since the final element isolation process does not depend on mechanical cutting, there is no adverse effect on the element due to mechanical cutting such as chipping. Therefore, the element is not separated or fallen down, so that the element is reliably separated while maintaining the quality of the element.
[0013]
An element transfer method according to the present invention that achieves the above object is an element transfer method for transferring a part of a plurality of elements arranged and formed on an element formation substrate to a transfer substrate. Adhesion process by bonding / peeling the substrate to the intermediate substrate so that the element and the intermediate substrate face each other, and the main surface of the element forming substrate opposite to the intermediate substrate is ground to thin the element forming substrate A separating step for separating the elements by etching between a plurality of elements of the element forming substrate from the ground surface where the grinding has been performed, and a transferring step for transferring the separated elements to the transfer substrate. It is characterized by.
[0014]
In the element transfer method according to the present invention as described above, when element isolation is performed, element isolation is performed by etching after thinning the element formation substrate. Therefore, the element isolation region at the time of element isolation is, for example, about 5 μm. As compared with the case where element separation is performed by conventional dicing, the width is significantly reduced. As such etching, for example, plasma dry etching using a chlorine-based gas is suitable.
[0015]
In addition, since the final element separation process does not depend on mechanical cutting, the element is not adversely affected by mechanical cutting such as chipping, and the element may be peeled off during the separation process. Since the device does not fall down, the device is reliably separated while maintaining the quality of the device, and the separated device is transferred with a good quality.
[0016]
Also, achieve the above purpose Rumo The element separation method is an element separation method for separating a plurality of elements formed on an element formation substrate, and forming an element separation groove on a main surface of the element formation substrate on which the elements are formed. The element forming substrate is thinned by grinding the forming process and the main surface of the element forming substrate opposite to the side where the element separating groove is formed, leaving a connecting portion of a predetermined thickness at the bottom of the element separating groove. And a separation step of separating the element by removing the connecting portion.
[0017]
As above Raw In the element separation method, the main surface of the element formation substrate opposite to the side on which the element separation groove is formed is ground to leave a connection portion having a predetermined thickness at the bottom of the element separation groove, and then the connection portion. To remove the element. Therefore, the presence of the connecting portion prevents the occurrence of defects due to the stress in the main surface direction of the element formation substrate in the element separation process.
[0018]
In this element isolation method, since the final element isolation process does not depend on mechanical cutting, there is no adverse effect on the element due to mechanical cutting such as chipping. Therefore, the element is not separated or fallen down, so that the element is reliably separated while maintaining the quality of the element.
[0019]
An element transfer method according to the present invention that achieves the above object is an element transfer method for transferring a part of a plurality of elements arranged and formed on an element formation substrate to a transfer substrate. Separation groove forming step for forming an element separation groove between elements on the main surface of the substrate on which the element is formed, and bonding the element formation substrate to the intermediate substrate with an adhesive / release layer so that the element and the intermediate substrate face each other The element forming substrate is thinned by grinding the main surface of the element forming substrate opposite to the side on which the element separating groove is formed to leave a connecting portion having a predetermined thickness at the bottom of the element separating groove. And a transfer step of transferring the separated element to a transfer substrate.
[0020]
In the element transfer method according to the present invention as described above, when element isolation is performed, the main surface on the opposite side of the element formation substrate on which the element isolation groove is formed is formed on the bottom of the element isolation groove with a predetermined thickness. Then, the device is ground to leave the connecting portion, and then the connecting portion is removed to separate the element. Therefore, the presence of the connecting portion prevents the occurrence of defects due to the stress in the main surface direction of the element formation substrate in the element separation process.
[0021]
And since the final element separation process does not depend on mechanical cutting, there is no adverse effect on the element due to mechanical cutting such as chipping, and the element may peel off during the separation process. Since the device does not fall down, the device is reliably separated while maintaining the quality of the device, and the separated device is transferred with a good quality.
[0022]
In the present invention, since an intermediate substrate that does not change its shape by irradiation with laser light is used, the intermediate substrate does not expand and contract even when the element is peeled off using laser light. It is possible to prevent a deviation in the pitch.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably.
[0024]
First, the first embodiment will be described. An element separation method according to the present invention is an element separation method for separating a plurality of elements formed on an element formation substrate, and grinding a main surface of the element formation substrate opposite to the element formed side. Then, a grinding process for thinning the element formation substrate and a separation process for separating the elements by etching a plurality of elements of the element formation substrate from the ground surface on which grinding has been performed are provided.
[0025]
An element transfer method according to the present invention to which the element separation method is applied is an element transfer method for transferring a part of a plurality of elements arranged and formed on an element formation substrate to a transfer substrate. The bonding substrate is bonded to the intermediate substrate with an adhesive / peeling layer so that the element and the intermediate substrate face each other, and the main surface of the element forming substrate opposite to the intermediate substrate is ground to thin the element forming substrate. A separating step for separating the elements by etching between the plurality of elements of the element forming substrate from the ground surface where the grinding is performed, and a transferring step for transferring the separated elements to the transfer substrate. It is to be prepared.
[0026]
In the first embodiment, the element separation method and the element transfer method described above will be described using an example in which an element (active chip) formed on a silicon substrate, which is an element formation substrate, is transferred to a transfer substrate.
[0027]
In order to separate and transfer elements according to the present invention, first, as shown in FIG. 1, a silicon substrate 1 which is an element formation substrate on which a wafer process step is completed and a plurality of elements are formed, and a quartz substrate which is an intermediate substrate. Are bonded by an adhesive / release layer. Here, a case where the adhesive / peeling layer includes the peeling layer 3 and the adhesive layer 4 will be described. First, a release layer 3 having a thickness of, for example, about 10 μm is formed by uniformly applying a resin onto the main surface of the silicon substrate 1 on which the element 2 is formed. Here, the release layer 3 serves to ablate and peel off the element from the fixing material when laser light is irradiated as described later. That is, the element 2 is peeled off from the fixing material by sublimating these materials at once with a laser beam. Therefore, the release layer 3 is made of a material that easily causes ablation when irradiated with laser light. In addition, it is preferable to use a low stress material so that the silicon substrate 1 which is an element formation substrate does not warp after the release layer 3 is formed. As a material constituting such a release layer 3, for example, polyimide, epoxy, silicon, build-up material or the like can be used. Moreover, the coating method at the time of forming the peeling layer 3 is not specifically limited, A conventionally well-known method, such as a method using a roller and a spin coater, can be used.
[0028]
Next, as shown in FIG. 2, an adhesive tape having both surfaces of adhesive layers 4 as an adhesive layer 4 is laminated on the release layer 3 of the silicon substrate 1 on which the release layer 3 is formed. A quartz substrate 5 is placed as an intermediate substrate made of a transmissive material, and the silicon substrate 1 as an element forming substrate and the quartz substrate 5 as an intermediate substrate are bonded. Here, as will be described later, the intermediate substrate has a light-transmitting property through which laser light can be transmitted when the release layer 3 is irradiated with laser light. The one that does not change the shape is used. As such an intermediate substrate, in addition to the quartz substrate 5, for example, a sapphire substrate, an alkali-free glass or the like is suitable. Further, as the alkali-free glass, specifically, 1737 (trade name, manufactured by Corning) or the like can be used.
[0029]
In the case where a conventional adhesive tape is used as the intermediate substrate, the adhesive tape burns and expands or contracts when the adhesive layer 13 is irradiated with laser light in a later step. Therefore, the transfer cannot be performed with high accuracy. This problem becomes more significant as the element becomes finer, and it becomes difficult to ensure transfer accuracy.
[0030]
However, in the present invention, since an intermediate substrate that does not change its shape even when irradiated with laser light is used, the intermediate substrate holding the element expands and contracts even when the element is separated in a later step. Therefore, it is possible to prevent a shift in the pitch of the separated elements and to transfer the elements with high accuracy.
[0031]
Next, as shown in FIG. 3, the silicon substrate 1 fixed to the quartz substrate 5 is mechanically ground by, for example, a polishing machine 6 to reduce the thickness to, for example, about 30 to 100 μm. At this time, the silicon substrate 1 grinds the main surface opposite to the quartz substrate 5, that is, the main surface opposite to the side where the element 2 is formed. As a means for grinding the silicon substrate 1, CMP (Chemical) is used. (Mechanical Polishing) or BGA can be used. In the present invention, the thinning of the silicon substrate 1 is not limited to such mechanical grinding. For example, the silicon substrate 1 is etched back entirely by dry etching. It is also possible to grind.
[0032]
Next, as shown in FIG. 4, a Si mask 7 is formed on the back surface of the thinned silicon substrate 1, that is, the main surface on the side subjected to the above grinding, as a mask used in dry etching described later. In order to form the Si mask 7, for example, a resin material such as a resist is applied to the main surface of the silicon substrate 1 that has been ground by spin coating. Next, patterning is performed by photolithography to open a desired region, that is, an element region. Then, Si is formed by plasma CVD using the patterned resist as a mask. Thereafter, the Si mask 7 can be formed by removing the resist. The mask material is not particularly limited as long as it is resistant to chlorine-based gas. For example, in addition to Si, for example, SiO or Si ₃ N ₄ Etc. can be used.
[0033]
Next, the back surface of the thinned silicon substrate 1, that is, the main surface on the side subjected to grinding in the above, is chlorinated using a Si mask 7, for example, CCl ₄ Plasma dry etching is performed. As a result, only the portion where the Si mask 7 is not formed, that is, the element isolation region is etched, and as a result, each element is isolated as shown in FIG. Here, the chlorine-based gas used for plasma dry etching is CCl. ₄ Besides SiCl ₄ , Cl ₂ Etc. can be used.
[0034]
Next, the element 2 separated on the quartz substrate 5 is transferred to the alkali-free glass substrate 8 as a transfer substrate. First, an adhesive layer 9 for adhering the element 2 is formed on the alkali-free glass substrate 8 by, for example, screen printing. Here, as the transfer substrate, a glass substrate such as non-alkali glass, a plastic substrate, or the like can be used. The adhesive layer 9 can be made of, for example, an acrylic resin. Then, the quartz substrate 5 is aligned with a predetermined position on the alkali-free glass substrate 8 on which the adhesive layer 9 is formed, and the element 2 to be transferred and the adhesive layer 8 are opposed to each other. After that, as shown in FIG. 6, from the back side of the quartz substrate 5, that is, the side opposite to the silicon substrate 1, for example, the upper part of the element 2 that transfers krypton fluorine (KrF) excimer laser light having a wavelength of 248 nm, that is, the element to be transferred. The release layer 3 corresponding to 2 is selectively irradiated. As a result, the peeling layer 3 is sublimated at once with KrF excimer laser light, and the element is peeled off from the quartz substrate 5. That is, the peeling layer 3 is ablated, and the element 2 is peeled from the quartz substrate 5 and bonded to the alkali-free glass substrate 8 by the adhesive layer 9 formed on the alkali-free glass substrate 8. As described above, the separated elements can be selectively transferred from the intermediate substrate to the transfer substrate.
[0035]
As described above, in the present invention, after thinning the silicon substrate 1 that is an element formation substrate, only the element isolation region is dry-etched to isolate each element 2. When element isolation is performed by dicing using a conventional diamond saw blade or the like, since the thickness of the rotating grindstone saw blade is, for example, about 30 μm to 40 μm, the width of the element isolation region must be set large. High density formation could not be achieved.
[0036]
However, in the present invention, since element isolation is performed by etching, the element isolation region at the time of element isolation can be significantly narrowed, for example, about 5 μm, compared to the case where element isolation is performed by dicing. As a result, it is possible to form elements at a high density on the element formation substrate, and to reduce the cost of the elements.
[0037]
In the case of element separation by conventional dicing, chipping of elements at the time of element separation, that is, occurrence of chipping of the elements becomes obvious. However, by separating each element 2 as described above, chipping of the element 2 at the time of element separation, that is, chipping of the periphery of the element, which has been a problem in conventional dicing, can be prevented. It is possible to prevent the occurrence of defective products. Then, it becomes possible to transfer an element having good quality. As a result, the yield can be improved and the productivity can be improved, so that the cost of the element can be reduced.
[0038]
Further, when element isolation is performed by dicing, the processing speed cannot be increased to prevent chipping, resulting in low-speed processing, and the element isolation process is significantly prolonged. However, in the present invention, since the entire element forming substrate can be isolated at once, the element isolation process time can be greatly shortened. Therefore, productivity can be improved and the cost of the element can be reduced.
[0039]
Further, in the present invention, the final separation of the elements does not depend on mechanical cutting, and no excessive stress is applied to the elements themselves. For this reason, even when the element itself is thinned, element separation does not affect the quality of the element, and it is possible to realize both the thinning of the element and the quality.
[0040]
In this element isolation method, since the final element isolation process does not depend on mechanical cutting, the element peels off during the isolation process due to stress in the main surface direction of the silicon substrate generated by mechanical cutting. Since it does not fall down, it is possible to reliably separate the elements while maintaining the quality of the elements, and it becomes possible to transfer the elements of good quality. This effect is particularly effective when the element is miniaturized.
[0041]
In the above description, the case where the element formation substrate is the silicon substrate 1 has been described. However, in the present invention, the element formation substrate is not limited to the silicon substrate 1, and for example, a group III-V compound semiconductor or II- A layer having a layer made of a group VI compound semiconductor can be used. Specifically, a GaAs substrate, a GaP substrate, a GaN substrate, and the like can be exemplified.
[0042]
Further, in the above description, the case where the adhesive / peeling layer is composed of two layers of the peeling layer 3 and the adhesive layer 4 has been described. It is not limited to what consists of layers, For example, an adhesion and peeling layer may consist of an adhesive layer single layer. That is, as shown in FIG. 7, an adhesive layer 10 may be formed on the silicon substrate 1 as an adhesive / peeling layer, and the silicon substrate 1 may be bonded to the quartz substrate 5 by the adhesive layer 10. In the case of such a configuration, when the adhesive layer 10 which is an adhesive / peeling layer is irradiated with laser light, the adhesive layer 10 absorbs the laser light and causes ablation, so that it can be peeled off. Therefore, a material that easily causes ablation when irradiated with laser light is used as the adhesive. As such an adhesive, for example, an epoxy adhesive can be used.
[0043]
Further, when the release layer 3 is irradiated with laser light, the entire surface of the quartz substrate 5 may be irradiated with laser light using a dedicated mask so that the other elements do not receive laser light. By using a mask, it is possible to irradiate only the element to be reliably transferred with laser light, so that selective transfer can be performed more reliably.
[0044]
Moreover, as a laser beam irradiated to a peeling layer when performing laser ablation, a YAG laser beam etc. other than a KrF excimer laser beam can be used.
[0045]
Further, by providing a silicon layer instead of the above-described adhesive layer 9 on the alkali-free glass substrate 8 as a transfer substrate, the element 2 peeled off from the quartz substrate 5 as an intermediate substrate can be surely captured. Then, it is possible to transfer the element 2 while preventing the positional deviation of the element 2 and the damage of the element.
[0046]
Next, another element separation method and element transfer method according to the present invention will be described. Another element separation method according to the present invention is an element separation method for separating a plurality of elements formed on an element formation substrate, the element separation on the main surface of the element formation substrate on which the element is formed. An isolation groove forming step for forming a groove, and an element formed by grinding the main surface of the element forming substrate opposite to the side on which the element isolation groove is formed, leaving a connecting portion of a predetermined thickness at the bottom of the element isolation groove It comprises a grinding step for thinning the formation substrate and a separation step for separating the elements by removing the connecting portions.
[0047]
An element transfer method according to the present invention to which the element transfer method is applied is an element transfer method for transferring a part of a plurality of elements arrayed on an element formation substrate to a transfer substrate. An isolation groove forming step for forming an element isolation groove between elements on the main surface of the forming substrate on which the element is formed, and an adhesive / release layer so that the element forming substrate is an intermediate substrate and the element and the intermediate substrate are opposed to each other. The element forming substrate is ground by grinding the bonding process of bonding and the main surface of the element forming substrate opposite to the side where the element separating groove is formed to leave a connecting portion of a predetermined thickness at the bottom of the element separating groove. It comprises a grinding process for thinning, a separating process for separating the elements by removing the connecting portion, and a transferring process for transferring the separated elements to the transfer substrate.
[0048]
In the second embodiment, the element separation method and the element transfer method described above will be described using an example in which an element (active chip) formed on a silicon substrate, which is an element formation substrate, is transferred to a transfer substrate.
[0049]
In order to perform element separation and transfer according to the present invention, first, as shown in FIG. 8, the wafer process step is completed, and the element 12 of the silicon substrate 11 which is an element formation substrate on which a thin film, a circuit pattern, etc. are formed. An adhesive / release layer is formed on the main surface on the formed side. Here, a case where the adhesive / peeling layer includes the peeling layer 13 and the adhesive layer 15 will be described.
[0050]
Here, the peeling layer 13 serves to ablate and peel off the element from the fixing material when laser light is irradiated as will be described later. That is, the element 12 is peeled off from the fixed material by sublimating these materials at once with a laser beam. Therefore, the release layer 13 is made of a material that easily causes ablation when irradiated with laser light. In addition, it is preferable to use a low stress material so that the silicon substrate 1 which is an element formation substrate does not warp after the release layer 13 is formed.
[0051]
As a material constituting such a release layer 13, for example, polyimide, epoxy, silicon, build-up material, or the like can be used. Moreover, the coating method at the time of forming the peeling layer 13 is not specifically limited, A conventionally well-known method, such as a method using a roller and a spin coater, can be used.
[0052]
Moreover, in order to adhere | attach the element 12 on the intermediate board mentioned later reliably, a gel-like adhesive material is used. As such an adhesive, for example, an epoxy adhesive can be used. The method for applying the adhesive is not particularly limited, and a conventionally known method such as a method using a roller or a spin coater can be used.
[0053]
Next, as shown in FIG. 9, element isolation grooves 14 for separating the elements 12 are formed on the release layer in the silicon substrate 11 on which the release layer 13 is formed. Here, the thickness of the silicon substrate is about 1 mm, and the element isolation groove is formed with a depth of about 100 μm, for example. The depth of the element isolation groove 14 is not particularly limited, and may be a value larger than the thickness of the element 12 and may be appropriately set depending on the element 12 to be manufactured. In addition, the element isolation groove 14 of the silicon substrate 11 is formed by, for example, a method using a rotating blade, or after opening an element isolation region by forming a resist on the silicon substrate 1 and patterning, for example, potassium hydroxide. Formed by wet etching with nitric acid, hydrofluoric acid based solution, or CCl ₄ It can be performed by a plasma dry etching method or the like.
[0054]
Next, an adhesive is applied on the silicon substrate 11 on which the element isolation grooves 14 are formed to form the adhesive layer 15. The adhesive is selectively applied so as not to enter the element isolation groove 14. The method for applying the adhesive is not particularly limited, and a known method such as rolling a roller with an adhesive on the silicon substrate 11 can be used. Here, a gel adhesive is used as the adhesive.
[0055]
Next, as shown in FIG. 10, a quartz substrate 16 that is an intermediate substrate made of a light-transmitting material is disposed on the silicon substrate 11 on which the release layer 13 and the adhesive layer 15 are formed. By performing the heat treatment, the adhesive is heated and cured to bond the quartz substrate 16 to the silicon substrate 11 as shown in FIG. In the present invention, the silicon substrate 11 as the element forming substrate is bonded to the quartz substrate 16 as the intermediate substrate using the gel adhesive as described above, and therefore the silicon substrate 11 is securely bonded to the quartz substrate 16. . As a result, the separated elements 12 are not peeled off from the quartz substrate 16 or fall down on the quartz substrate 16 even during the subsequent process. In addition, as the intermediate substrate, a substrate that has optical transparency and does not cause a shape change such as expansion or contraction even when irradiated with laser light is used. As such an intermediate substrate, a glass substrate is suitable in addition to the quartz substrate 16. Here, when a conventional pressure-sensitive adhesive tape is used as the intermediate substrate, the pressure-sensitive adhesive tape burns and expands or contracts when the adhesive layer 13 is irradiated with a laser beam in a later step. As a result, a deviation occurs in the pitch of the formed elements, and transfer cannot be performed with high accuracy. This problem becomes more significant as the element becomes finer, and it becomes difficult to ensure transfer accuracy.
[0056]
However, in the present invention, since an intermediate substrate that does not change its shape even when irradiated with laser light is used, the intermediate substrate holding the element expands and contracts even when the element is separated in a later step. Therefore, it is possible to prevent a shift in the pitch of the separated elements and to transfer the elements with high accuracy.
[0057]
Next, as shown in FIG. 12, the silicon substrate 11 is ground and thinned from the back side. At this time, the silicon substrate 11 is ground in a state where the connecting portion 17 having a predetermined thickness is left at the bottom of the element isolation groove 14 provided earlier. Thus, since the state where the elements 12 are connected to each other is maintained by leaving the connecting portion 17 at the bottom of the element isolation groove 14, the element peels off due to the stress in the main surface direction of the silicon substrate 11 caused by grinding, It is prevented from falling down. Therefore, it is possible to use an adhesive having a relatively weak adhesive force, and the degree of freedom in selecting the adhesive is increased. Here, for example, when the thickness of the substrate is about 70 μm, the thickness of the connecting portion can be about 5 μm to 50 μm, but is not particularly limited and can be changed as appropriate.
[0058]
Next, the connecting portion 17 is removed regardless of mechanical means. That is, the back surface of the quartz substrate 16, that is, the main surface on the side ground in the above, is made, for example, CCl, which is a chlorine-based gas. ₄ Etching is performed by plasma dry etching. Thereby, as shown in FIG. 13, the connecting portion 17 left at the bottom of the element isolation groove 14 is removed, and as a result, each element is isolated. Here, the gas used for plasma dry etching is CCl. ₄ Besides SiCl ₄ , Cl ₂ Etc. can be used.
[0059]
Next, the element 12 separated on the quartz substrate 16 is transferred to a non-alkali glass substrate 18 as a transfer substrate. First, an adhesive layer 19 for adhering the element 12 is formed on the alkali-free glass substrate 18 by, for example, screen printing. Here, as the transfer substrate, a glass substrate such as non-alkali glass, a plastic substrate, or the like can be used. The adhesive layer 19 can be made of, for example, an acrylic resin. Then, the quartz substrate 16 is aligned with a predetermined position on the alkali-free glass substrate 18 on which the adhesive layer 19 is formed, and the element 12 to be transferred and the adhesive layer 18 are opposed to each other. After that, as shown in FIG. 14, from the back side of the quartz substrate 16, that is, the side opposite to the silicon substrate 11, for example, the upper part of the element 2 that transfers krypton fluorine (KrF) excimer laser light having a wavelength of 248 nm, that is, the element to be transferred. The release layer 3 corresponding to 12 is selectively irradiated. Thereby, the element 12 is peeled off from the quartz substrate 16 by sublimating the peeling layer 13 at once with KrF excimer laser light. That is, the peeling layer 13 is ablated, and the element 12 is peeled from the quartz substrate 16 and bonded to the alkali-free glass substrate 18 by the adhesive layer 19 formed on the alkali-free glass substrate 18. As described above, the separated elements can be selectively transferred from the intermediate substrate to the transfer substrate.
[0060]
As described above, in the present invention, when the silicon substrate 11 that is an element forming substrate is thinned, the connection portion 17 having a predetermined thickness is ground and etched to etch the connection portion. The part 17 is removed and element isolation is performed. In conventional element separation by dicing, stress in the main surface direction of the silicon substrate 11 is generated, so that the element is peeled off from the intermediate substrate or falls on the intermediate substrate. As the element becomes finer, it becomes more difficult to maintain the adhesive force between the element and the intermediate substrate. This problem becomes more prominent as the element becomes finer.
[0061]
However, in the present invention, the connecting portion 17 prevents the element from peeling off or falling down due to the stress in the main surface direction of the silicon substrate 11 that occurs during the thinning grinding. Since the final element separation is performed by etching, stress in the main surface direction of the silicon substrate 11 is not generated, and the element can be separated while being bonded to a predetermined position of the intermediate substrate. . In the present invention, since a gel-like adhesive is used when bonding the silicon substrate 11 to the quartz substrate 16 as an intermediate substrate, it is compared with a case where a sol-like adhesive such as an adhesive tape is used. Thus, the element 12 can be more securely bonded to the quartz substrate 16 as an intermediate substrate, and the element 12 is peeled off from the quartz substrate 16 or falls on the quartz substrate 16 during the element separation process. There is nothing.
[0062]
Therefore, in the present invention, generation of defective products due to stress in the main surface direction of the silicon substrate at the time of element isolation is prevented. As a result, the yield can be improved and the productivity can be improved, so that the cost of the element can be reduced. This effect is particularly effective when the element is miniaturized.
[0063]
Further, in the case of element separation by dicing, the thickness of the rotating grindstone saw blade is, for example, about 30 μm to 40 μm, so the width of the element separation region has to be set large, and high density formation of elements on the element formation substrate cannot be achieved. . However, in the present invention, since the final device isolation is performed by etching, the device isolation groove is also formed by etching, so that the device isolation region at the time of device isolation is, for example, about 5 μm, and device isolation is performed by dicing. It is possible to make it significantly narrower than that. As a result, it is possible to form elements at a high density on the element formation substrate, and to reduce the cost of the elements.
[0064]
Further, when element isolation is performed by dicing, the processing speed cannot be increased to prevent chipping, resulting in low-speed processing, and the element isolation process is significantly prolonged. However, in the present invention, since the entire element forming substrate can be isolated at once, the element isolation process time can be greatly shortened. Therefore, productivity can be improved and the cost of the element can be reduced.
[0065]
In addition, the final separation of the element in the present invention does not depend on mechanical cutting, and no excessive stress is applied to the element itself. For this reason, even when the element itself is thinned, element separation does not affect the quality of the element, and it is possible to realize both the thinning of the element and the quality.
[0066]
In the above description, the case where the element formation substrate is the silicon substrate 1 has been described. However, in the present invention, the element formation substrate is not limited to the silicon substrate 1, and for example, a group III-V compound semiconductor or II- A layer having a layer made of a group VI compound semiconductor can be used. Specifically, a GaAs substrate, a GaP substrate, a GaN substrate, and the like can be exemplified.
[0067]
Further, in the above description, the case where the adhesive / peeling layer is composed of two layers of the peeling layer 13 and the adhesive layer 15 has been described. However, in the present invention, the adhesive / peeling layer is the two layers of the peeling layer 13 and the adhesive layer 15. It is not limited to what consists of layers, For example, an adhesion and peeling layer may consist of an adhesive layer single layer. That is, as shown in FIG. 15, an adhesive layer 20 may be formed on the silicon substrate 11 as an adhesive / peeling layer, and the silicon substrate 11 may be bonded to the quartz substrate 16 by the adhesive layer 20. In the case of such a configuration, when the adhesive layer 20 which is an adhesive / peeling layer is irradiated with laser light, the adhesive layer 10 absorbs the laser light and causes ablation, so that it can be peeled off. Therefore, a material that easily causes ablation when irradiated with laser light is used as the adhesive. As such an adhesive, for example, an epoxy adhesive can be used.
[0068]
In the above description, the connecting portion 17 is removed by etching the entire back surface of the silicon substrate 11. However, the connecting portion 17 may be removed by etching only the connecting portion 17 by providing a mask. In the above description, the connection portion 17 is removed by dry etching. However, the present invention is not limited to this, and the connection portion 17 can also be removed by wet etching.
[0069]
Further, when the release layer 3 is irradiated with laser light, the entire surface of the quartz substrate 5 may be irradiated with laser light using a dedicated mask so that the other elements do not receive laser light. By using a mask, it is possible to irradiate only the element to be reliably transferred with laser light, so that selective transfer can be performed more reliably.
[0070]
Moreover, as a laser beam irradiated to a peeling layer when performing laser ablation, a YAG laser beam etc. other than a KrF excimer laser beam can be used.
[0071]
Further, by providing a silicon layer on the alkali-free glass substrate 18 as a transfer substrate instead of the adhesive layer 19 described above, the element 12 peeled off from the quartz substrate 16 as an intermediate substrate can be surely captured. It is possible to transfer the element 12 while preventing displacement of the element 12 and damage to the element.
[0072]
Next, a third embodiment of the present invention will be described. In the third embodiment, a case will be described in which element isolation is performed using laser light instead of etching in the above-described second embodiment.
[0073]
First, similarly to the second embodiment, the silicon substrate 11 as the element forming substrate is bonded to the quartz substrate 16 as the intermediate substrate, and the back surface of the silicon substrate 11 is ground to connect the connecting portion 17 as shown in FIG. Reduce the thickness while leaving
[0074]
Next, an adhesive layer 19 for adhering the element 12 is formed on the alkali-free glass substrate 18 as a transfer substrate by, for example, screen printing. Then, the quartz substrate 16 is aligned with a predetermined position on the alkali-free glass substrate 18 on which the adhesive layer 19 is formed, and the element 12 to be transferred and the adhesive layer 18 are opposed to each other. Thereafter, as shown in FIG. 14, the upper portion of the element 2 that transfers, for example, krypton fluorine (KrF) excimer laser light having a wavelength of 248 nm from the back surface side of the quartz substrate 16, that is, the side where the element 12 is formed on the silicon substrate 11. That is, the peeling layer 3 corresponding to the element 12 to be transferred and the connection portion 17 connecting the element 12 to another element are selectively irradiated. Thereby, the silicon of the connecting portion 17 irradiated with the laser light is sublimated and removed, and as a result, the desired element 12 is separated. At the same time, the element 12 is peeled from the quartz substrate 16 by sublimating the peeling layer 13 at once with a laser beam. That is, the peeling layer 13 is ablated, and the element 12 is peeled from the quartz substrate 16 and bonded to the alkali-free glass substrate 18 by the adhesive layer 19 formed on the alkali-free glass substrate 18. Here, by selecting the irradiation conditions of the laser beam such as irradiation energy and wavelength, both the silicon sublimation and the ablation of the release layer 13 can occur simultaneously, and the element 12 can be transferred as described above. As described above, the separated elements can be selectively transferred from the intermediate substrate to the transfer substrate.
[0075]
Even in the above method, the effects of the present invention described in the second embodiment described above can be obtained, and element separation and transfer can be performed efficiently and reliably. Furthermore, since the final separation and transfer of the element can be performed only by laser light irradiation, the process can be simplified and the process time can be further shortened.
[0076]
In the above description, the case where the final separation and transfer of the element are simultaneously performed has been described. However, the connection portion 17 is first removed without performing the final separation and transfer of the element at the same time. The separated element 12 may be transferred. In this case, the irradiation condition of the laser beam may be changed depending on when the connecting portion 17 is removed and when the separated element 12 is transferred. Moreover, when removing the connection part 17, you may irradiate a laser beam from the side which gave the grinding | polishing for thickness reduction of the silicon substrate 11. FIG.
[0077]
Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, a case will be described in which, in the third embodiment described above, the element isolation groove 14 is formed first, and then the release layer 13 is formed.
[0078]
First, as shown in FIG. 16, element isolation grooves 14 are formed in a silicon substrate 11 which is an element formation substrate. Then, as shown in FIG. 17, a release layer 13 is formed on the silicon substrate 11 on which the element isolation grooves 14 are formed. At this time, the resin of the release layer 13 is prevented from entering the element isolation groove 14.
[0079]
Next, as shown in FIG. 18, the adhesive layer 15 is formed by applying a gel adhesive to the main surface of the quartz substrate 16 as an intermediate substrate. Then, the silicon substrate 11 on which the release layer 13 is formed and the quartz substrate 16 on which the adhesive layer 15 is formed are overlapped so that the release layer 13 and the adhesive layer 15 face each other, for example, at a temperature of 200 ° C. for 30 minutes. By heating the adhesive, the adhesive is heated and cured to adhere the quartz substrate 16 to the silicon substrate 11.
[0080]
Next, as shown in FIG. 19, the silicon substrate 11 is ground and thinned from the back side. At this time, the silicon substrate 11 is ground in a state where the connecting portion 17 having a predetermined thickness is left at the bottom of the element isolation groove 14 provided earlier.
[0081]
Next, an adhesive layer 19 for adhering the element 12 is formed on the alkali-free glass substrate 18 as a transfer substrate by, for example, screen printing. Then, the quartz substrate 16 is aligned with a predetermined position on the alkali-free glass substrate 18 on which the adhesive layer 19 is formed, and the element 12 to be transferred and the adhesive layer 18 are opposed to each other. After that, as shown in FIG. 14, from the back side of the quartz substrate 16, that is, the side opposite to the silicon substrate 11, for example, the upper part of the element 2 that transfers krypton fluorine (KrF) excimer laser light having a wavelength of 248 nm, that is, the element to be transferred. 12 is selectively irradiated to the peeling layer 3 corresponding to 12 and the connection portion 17 connected to the other elements. Thereby, the silicon of the connecting portion 17 irradiated with the laser light is sublimated and removed, and as a result, the desired element 12 is separated. At the same time, the peeling layer 13 is ablated, and the element 12 is peeled from the quartz substrate 16 and bonded to the alkali-free glass substrate 18 by the adhesive layer 19 formed on the alkali-free glass substrate 18. As described above, the separated elements can be selectively transferred from the intermediate substrate to the transfer substrate.
[0082]
Even in the method as described above, the effects of the present invention described in the second embodiment can be obtained, and element separation and transfer can be performed efficiently and reliably.
[0083]
【The invention's effect】
An element isolation method according to the present invention is an element isolation method for isolating a plurality of elements formed on an element formation substrate, the main surface of the element formation substrate opposite to the side on which the element is formed. And a separation step of separating the elements by etching between the plurality of elements of the element formation substrate from the ground surface on which the grinding has been performed. Is.
[0084]
In the element isolation method according to the present invention as described above, element isolation is performed by etching after the element formation substrate is thinned, so that the element isolation region during element isolation can be significantly narrowed. In addition, since the final element separation process does not depend on mechanical cutting, the elements can be reliably separated while maintaining a high quality state. Accordingly, it is possible to form elements on the element formation substrate at a high density, and thus it is possible to provide a semiconductor device at low cost.
[0085]
The element transfer method according to the present invention is an element transfer method for transferring a part of a plurality of elements arranged on an element formation substrate to a transfer substrate, wherein the element formation substrate is used as an intermediate substrate. A bonding process in which the element and the intermediate substrate are bonded to each other by an adhesive / peeling layer, and a grinding of the main surface of the element forming substrate opposite to the intermediate substrate to reduce the thickness of the element forming substrate. A separation step of separating the elements by etching the plurality of elements of the element formation substrate from the ground surface on which the grinding is performed, and a transfer step of transferring the separated elements to a transfer substrate. Is provided.
[0086]
In the element transfer method according to the present invention as described above, when element isolation is performed, element isolation is performed by etching after thinning the element formation substrate, so that the element isolation region during element isolation is greatly reduced. Is possible. In addition, since the final element separation process does not depend on mechanical cutting, the elements can be reliably separated while maintaining a high quality state, and high quality elements can be transferred. Accordingly, it is possible to form elements on the element formation substrate at a high density, and thus it is possible to provide a semiconductor device at low cost.
[0087]
The element separation method according to the present invention is an element separation method for separating a plurality of elements formed on an element formation substrate, and is provided on the main surface of the element formation substrate on the side where the elements are formed. An isolation groove forming step for forming an element isolation groove, and a state in which the main surface of the element formation substrate opposite to the side on which the element isolation groove is formed leaves a connecting portion having a predetermined thickness at the bottom of the element isolation groove A grinding process for thinning the element forming substrate to a thickness, and a separation process for separating the element by removing the connecting portion.
[0088]
In the element isolation method according to the present invention as described above, the main surface of the element formation substrate opposite to the side where the element isolation groove is formed is in a state in which a connecting portion having a predetermined thickness is left at the bottom of the element isolation groove. Then, the connecting portion is removed and the element is separated. Therefore, due to the presence of the connecting portion, it is possible to prevent the occurrence of defects due to the stress in the main surface direction of the element formation substrate in the element isolation process. In addition, since the final element separation process does not depend on mechanical cutting, the elements can be reliably separated while maintaining a high quality state. Therefore, it is possible to accurately and reliably separate elements formed on the substrate, and thus it is possible to provide a semiconductor device at low cost.
[0089]
The element transfer method according to the present invention is an element transfer method for transferring a part of a plurality of elements arrayed on an element formation substrate to a transfer substrate, wherein the element on the element formation substrate is transferred to the element transfer substrate. An isolation groove forming step for forming an element isolation groove between elements on the main surface on the formed side, and an adhesion in which the element formation substrate is bonded to the intermediate substrate by an adhesive / release layer so that the element and the intermediate substrate face each other And grinding the main surface of the element formation substrate opposite to the side where the element isolation groove is formed to a state in which a connecting portion having a predetermined thickness is left at the bottom of the element isolation groove. It comprises a grinding step for thinning, a separation step for removing the connecting portion to separate the elements, and a transfer step for transferring the separated elements to a transfer substrate.
[0090]
In the element transfer method according to the present invention as described above, when element isolation is performed, the main surface on the opposite side of the element formation substrate on which the element isolation groove is formed is formed on the bottom of the element isolation groove with a predetermined thickness. Then, the device is ground to leave the connecting portion, and then the connecting portion is removed to separate the element. Therefore, the presence of the connecting portion can prevent the occurrence of defects due to stress in the main surface direction of the element formation substrate in the element isolation process. In addition, since the final element separation process does not depend on mechanical cutting, it is possible to reliably separate elements while maintaining a high quality state, and to transfer high quality elements accurately and reliably. Accordingly, the semiconductor device can be provided at a low cost.
[Brief description of the drawings]
FIG. 1 is a process diagram illustrating a process according to a first embodiment of the present invention.
FIG. 2 is a process diagram illustrating a process according to the first embodiment of the present invention.
FIG. 3 is a process diagram illustrating a process of the first embodiment according to the present invention.
FIG. 4 is a process diagram illustrating a process according to the first embodiment of the present invention.
FIG. 5 is a process diagram illustrating a process according to the first embodiment of the present invention.
FIG. 6 is a process diagram illustrating a process of the first embodiment according to the present invention.
FIG. 7 is a process diagram for explaining a process of the first embodiment according to the present invention.
FIG. 8 is a process diagram illustrating a process according to a second embodiment of the present invention.
FIG. 9 is a process diagram illustrating a process according to a second embodiment of the present invention.
FIG. 10 is a process diagram illustrating a process according to a second embodiment of the present invention.
FIG. 11 is a process diagram illustrating a process according to a second embodiment of the present invention.
FIG. 12 is a process diagram illustrating a process according to a second embodiment of the present invention.
FIG. 13 is a process diagram illustrating a process according to a second embodiment of the present invention.
FIG. 14 is a process diagram illustrating a process according to a second embodiment of the present invention.
FIG. 15 is a process diagram illustrating a process according to a second embodiment of the present invention.
FIG. 16 is a process diagram illustrating a process according to a fourth embodiment of the present invention.
FIG. 17 is a process diagram illustrating a process according to a fourth embodiment of the present invention.
FIG. 18 is a process diagram illustrating a process according to a fourth embodiment of the present invention.
FIG. 19 is a process diagram illustrating a process according to a fourth embodiment of the present invention.
FIG. 20 is a diagram illustrating a conventional DBG process.
FIG. 21 is a diagram illustrating a conventional DBG process.
[Explanation of symbols]
1 silicon substrate, 2 elements, 3 peeling layer, 4 adhesive layer, 5 quartz substrate, 6 polishing machine, 7 Si mask, 8 transfer substrate, 9 adhesive layer

Claims (28)

Adhesion that causes ablation when laser light is applied to an element formation substrate on which multiple elements are arrayed and an intermediate substrate that is transparent to laser light and does not change shape when irradiated with laser light Bonding the element and the intermediate substrate so as to face each other by a release layer;
Grinding the main surface of the element forming substrate opposite to the intermediate substrate to thin the element forming substrate; and
A separation step of separating the elements by etching the plurality of elements of the element formation substrate from the ground surface on which the grinding is performed;
A transfer step of transferring the separated element to a transfer substrate by irradiating the adhesive / peeling layer with laser light and causing ablation . The laser beam, transfer method according to claim 1 element, wherein the excimer laser light or YAG laser light. By irradiating selectively the adhesive-release layer the laser beam, device transfer method according to claim 1, wherein the selecting transferring the element. Intermediate substrate is a quartz substrate having the light-transmitting, a sapphire substrate, device transfer method according to claim 1, wherein either non-alkali glass substrate.   The adhesive / peeling layer is formed by laminating an adhesive layer and a peeling layer, the peeling layer is provided in contact with the element, and the adhesive layer is provided in contact with the intermediate substrate. Element transfer method. At least polyimide, device transfer method according to claim 5, wherein each comprising one of Epoxy the release layer.   The element transfer method according to claim 1, wherein the etching is dry etching. The element transfer method according to claim 7, wherein the dry etching is performed using a chlorine-based gas. The element transfer method according to claim 8 , wherein the chlorine-based gas is any one of SiCl ₄ , CCl ₄ , and Cl ₂ . The separation step is
A mask forming step of forming a mask on the ground surface;
2. An element transfer method according to claim 1, further comprising: an etching step in which the plurality of elements of the element formation substrate are etched from the ground surface side where the grinding is performed using the mask.   The element transfer method according to claim 1, wherein the element formation substrate has a layer made of any one of Si, a III-V group compound semiconductor, and a II-VI group compound semiconductor.   12. The device transfer method according to claim 11, wherein the III-V compound semiconductor is any one of GaAs, GaP, and GaN. An isolation groove forming step of forming an element isolation groove between elements on the main surface on which the element is formed of an element forming substrate on which a plurality of elements are arranged;
The element-forming substrate and an intermediate substrate that is transparent to laser light and does not change in shape when irradiated with laser light are bonded to the element by an adhesive / release layer that causes ablation when irradiated with laser light. Bonding the intermediate substrate so as to face the intermediate substrate;
The element forming substrate is thinned by grinding the main surface of the element forming substrate on the side opposite to the side where the element separating groove is formed to leave a connecting portion having a predetermined thickness at the bottom of the element separating groove. Grinding process;
A separation step of separating the element by removing the connecting portion;
A transfer step of transferring the separated element to a transfer substrate by irradiating the adhesive / peeling layer with laser light and causing ablation . The element transfer method according to claim 13 , wherein the laser light is excimer laser light or YAG laser light. The element transfer method according to claim 13 , wherein the element is selectively transferred by selectively irradiating the adhesive / release layer with the laser beam. 14. The element transfer method according to claim 13, wherein the light-transmitting intermediate substrate is a quartz substrate, a sapphire substrate, or an alkali-free glass substrate. The adhesive-release layer, an adhesive layer and a release layer formed by laminating, the release layer is provided in contact with the element, the adhesive layer according to claim 13 provided in contact with the intermediate substrate Element transfer method. At least polyimide, device transfer method according to claim 17, wherein each comprising one of Epoxy the release layer. 14. The device transfer method according to claim 13, wherein in the separation step, the connecting portion is removed by irradiating the connecting portion with laser light. The element transfer method according to claim 19, wherein the laser beam is irradiated from a side of the element formation substrate on which the element is formed.   The element transfer method according to claim 19, wherein the laser beam is irradiated from the ground side. The element transfer method according to claim 13, wherein in the separation step, the connecting portion is removed by etching the connecting portion. 23. The device transfer method according to claim 22 , wherein the etching is dry etching. 24. The device transfer method according to claim 23, wherein the dry etching is performed using a chlorine-based gas. The element transfer method according to claim 24 , wherein the chlorine-based gas is any one of SiCl ₄ , CCl ₄ , and Cl ₂ . 23. The device transfer method according to claim 22 , wherein the etching is wet etching. The element transfer method according to claim 13 , wherein the element formation substrate has a layer made of any one of Si, a group III-V compound semiconductor, and a group II-VI compound semiconductor. 28. The device transfer method according to claim 27 , wherein the group III-V compound semiconductor is GaAs, GaP, or GaN.

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