JPH06275717A - Wafer peeling method - Google Patents

Abstract

PURPOSE:To eliminate a crack of a wafer when the wafer adhered with wax to a jig is peeled from the jig and to improve its throughput. CONSTITUTION:An acrylic plate 5 for reinforcing a wafer 1 is inserted between the wafer 1 and a glass plate 3, a force is applied to the plate 5 to be peeled from the plate 3, then dipped in acetone solvent 6 to dissolve wax 2, the plate 5, and the wafer 1 is removed. Thus, since this method allows application of no mechanical force to the wafer itself, the wafer is not cracked, and it has its yield improving effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer peeling method for peeling a wafer stuck by a wax to a wafer sticking jig.

[0002]

2. Description of the Related Art In some semiconductor manufacturing processes, it is necessary to form a device pattern on the front surface of a wafer, grind and polish the wafer to a thickness of about 100 μm, and then form electrodes on the rear surface of the wafer in the subsequent process. There is something. For example, when using a round wafer with a diameter of 3 inches,
When electrodes are formed on the back surface of the wafer by using various vapor deposition devices in a state where the thickness of the wafer is reduced to about 100 μm, cracks or cracks are always generated in the wafer.

As described above, the wafer 1 is coated with the wax 2 on the glass plate (jig) as shown in FIG. 6 in order to prevent the wafer from cracking in the semiconductor manufacturing process after the grinding including the workability in grinding and the electrode forming process. As shown in FIG. 8, the semiconductor is manufactured in the state of being attached to the glass plate 3, and the wafer 1 in the state of being attached to the glass plate 3 is placed in a water tank (organic layer) 7 containing a solvent (organic solvent) 60 as shown in FIG. Inside, the wafer 1 was peeled off from the glass plate 3. Reference numeral 11 denotes an electrode formed on the entire back surface of the wafer 1.

Details of the above steps will be described with reference to FIG. First, the wax 2 is applied on the glass plate 3, and the device pattern (not shown) is formed on the surface of the wax 2.
The wafer 1 on which is formed is attached so that the front surface side faces the glass plate 3 and is parallel to the glass plate 4 as much as possible (FIG. 7).
(a), (b)).

Next, the wafer 1 is ground to a constant thickness by using a grinding device, and thereafter, in order to remove defects generated by the grinding, polishing is performed to perform mirror-finishing of the wafer 1.
Next, an electrode 11 is formed on the entire back surface of the wafer 1 by using a vapor deposition device (FIG. 2 (c)). At this time, it is necessary to set vapor deposition conditions such that the temperature of the wafer 1 falls below the softening temperature of the wax 2 with the wafer 1 stuck to the glass plate 3.

After the above steps are completed, the wafer peeling step is started. First, as shown in FIG. 8, a water tank 7 having a constant volume is prepared, and an organic solvent 60 capable of dissolving the wax 2 therein is prepared.
Put in. The wafer 1 stuck with the wax 2 on the glass plate 3 is immersed in this. At this time, it is known that the peeling time can be shortened by stirring the wafer 1 and raising the temperature of the organic solvent 60. However, when the organic solvent 60 melts the wax 2, the outer peripheral portion of the wafer 1 (the edge portion of the wafer)
Since the organic solvent 60 permeates only from above, the wafer 1
In order to melt the wax 2 under the central portion, that is, the wafer 1 is peeled off from the glass plate 3 and becomes as shown in FIG. 7 (h),
It took about a week.

In addition to the method of melting the wax with an organic solvent to peel the wafer, there is also a method of peeling the wafer from the glass plate by using a wafer peeling machine and applying mechanical stress. FIG. 9 is a diagram showing a state in which a glass plate and a wafer are adsorbed by the heat chucks 4a and 4b, respectively, and stress is applied while being heated to a predetermined temperature.

Next, a method for removing the wafer will be described.
First, the wafer 1 stuck to the glass plate 3 with the wax 2 is vacuum-adsorbed on the heat chuck 4a with the wafer 1 facing down. Next, the heat chuck 4a and the heat chuck 4b
Is heated to a temperature at which wax 2 melts, and wax 2 is melted. At this time, the heat chuck 4b is not in contact with the glass plate 3. Next, the heat chuck 4b is lowered to adsorb the glass plate 3. Next, while maintaining the parallelism between the heat chuck 4a and the heat chuck 4b, the heat chuck 4b is moved in the arrow direction to mechanically separate the wafer 1 and the glass plate 3.

[0009]

The conventional wafer peeling method is configured as described above. In the method of peeling a wafer from a glass plate using a solvent, it takes time to melt all the wax, so that the wafer is peeled off. It took about one week, and the throughput was low. Further, in the method of peeling the wafer from the glass plate by using a mechanical peeling machine and mechanical stress, the processing can be performed quickly, but the cracking of the wafer occurs due to the application of force and the deviation of the parallelism of the heat chuck. Moreover, especially when the wafer is thin (up to 100 μm), there is a problem that wafer cracking often occurs.

The present invention has been made to solve the above problems, and provides a wafer peeling method capable of improving throughput, eliminating wafer cracks, and improving yield. To aim.

[0011]

According to the wafer peeling method of the present invention, a wafer fixed on a glass plate which is a jig through a wafer reinforcing plate is peeled off together with the reinforcing plate by mechanical force, and then the wafer is removed. The reinforcing plate as it is attached is soaked in a solvent to selectively melt the reinforcing plate so that only the wafer remains.

Further, the wafer peeling method according to the present invention is such that the wafer adhered to the glass plate with the adhesive is brought to an extremely low temperature to make the adhesive brittle, and further ultrasonic waves are applied to clean the wafer. The wafer and the glass plate are separated from each other.

Further, the wafer peeling method according to the present invention has a structure in which the wafer has a groove penetrating to the glass plate at a predetermined portion, and in this state, the wafer is soaked in a solvent to dissolve the adhesive. The wafer and the glass plate are separated from each other.

[0014]

According to the present invention, the wafer together with the reinforcing plate is peeled off from the jig by mechanical force, and the reinforcing plate with the wafer is soaked in the solvent to selectively dissolve the reinforcing plate to cure the wafer and the wafer. Since the wafer is separated from the tool, the wafer can be separated from the jig without applying mechanical force to the wafer itself.

Further, the wafer adhered to the jig with the adhesive is brought into a cryogenic state to make the adhesive brittle, and the wafer adhered to the jig is ultrasonically cleaned with the brittle adhesive. Since the wafer and the jig are separated from each other, the wafer can be separated from the jig without applying a mechanical force to the wafer.

Further, since the groove is formed in the wafer through the jig, the organic solvent can permeate not only from the peripheral portion of the wafer but also from the peripheral portion of the groove, so that the dissolution of the adhesive is promoted. .

[0017]

EXAMPLES Example 1. FIG. 1 is a diagram for explaining a wafer peeling method according to the first embodiment of the present invention.
The same reference numerals denote the same or corresponding portions, and 5 denotes the wafer 1.
It is an acrylic plate for reinforcing and is placed between the wafer 1 and the glass plate 3 with the wax 2 interposed therebetween. 6 is an acetone solvent for dissolving the acrylic plate 5 and the wax 2, and 7 is an organic tank.

Next, a method for removing the wafer will be described.
First, the wafer 1 is stuck to the acrylic plate 5 with the wax 2, and the acrylic plate 5 is stuck to the glass plate 3 with the wax 2. Then, as shown in FIG. 1A, the glass plate 3 on which the wafer 1 and the acrylic plate 5 are mounted is fixed to the heat chuck 4a by vacuum adsorption, and in this state, the heat chuck 4a is heated to the melting point of the wax 2,
The acrylic plate 5 is mechanically extruded in the method shown by the arrow to separate the acrylic plate 5 with the wafer 1 from the glass plate 3.

FIG. 1 (b) shows a state of an acrylic plate 5 in which a wafer 1 separated from a glass plate 3 is attached with a wax 2. Next, as shown in FIG. 1 (c), an organic tank 7 filled with acetone 6 is prepared in the state as shown in FIG. 1 (b).
insert. At this time, the acrylic plate 5 and the wax 2 applied to the acetone 6 are dissolved, and only the wafer 1 remains in the organic tank 7.

As described above, according to this embodiment, the wafer 1 is attached to the glass plate 3 via the acrylic plate 5 with the wax 2, and the wafer 1 is separated from the glass plate 3 together with the acrylic plate 5. Since this is soaked in the acetone solvent 6 to dissolve the wax 2 and the acrylic plate 5, this can be separated from the glass plate 3 without applying mechanical force to the wafer 1 itself, and the wafer can be peeled off. It is possible to eliminate cracks during work.

Example 2. Next, a wafer peeling method according to the second embodiment of the present invention will be described with reference to FIG. In the figure, 8 is a low temperature tank for liquid nitrogen, 9 is liquid nitrogen for fragile the wax 2 even at low temperature, and 10 is ultrasonic cleaning for removing the fragile wax 2a between the wafer 1 and the glass plate 3. It is a tank.

Next, the method for removing the wafer will be described.
FIG. 2A shows a state in which the wafer 1 is attached to the glass plate 3 with the wax 2. Then, as shown in FIG. 2 (b), the glass plate 3 with the wafer 1 shown in FIG. 2 (a) is put into liquid nitrogen 9 so that the wax 2 becomes brittle.

Further, in FIG. 2 (c), the wafer 1 attached to the glass plate 3 is put into the ultrasonic cleaning tank 10 by the wax 2a which has become brittle in the step of FIG. 2 (b), and it becomes brittle by applying ultrasonic waves. The wax 2a is separated from the glass plate 3, and the wafer 1 and the glass plate 3 can be separated.

As described above, according to this embodiment, the wax 2
The wafer 1 adhered to the glass plate 3 by the above is soaked in the low-temperature bath 8 for liquid nitrogen to make the wax 2 brittle, and this is washed in the ultrasonic cleaning bath 10. It can be peeled off from the glass plate 3 without applying.

Example 3. Next, a wafer peeling method according to the third embodiment of the present invention will be described with reference to FIG. In the figure, reference numeral 12 is a groove formed in a predetermined portion of the wafer 1 so as to reach the glass plate 3.

Next, the manufacturing method will be described with reference to FIG. Since the electrode forming process (FIGS. 4A to 4C) is the same as the conventional process, only the process after forming the electrode will be described here. First, a resist pattern 13 for forming a groove is formed on the wafer 1 on which the electrodes 11 are formed by using a normal transfer technique (FIG. 4 (d)). Next, as shown in FIG. 4 (e), a plurality of grooves 12 (see FIG. 3 (b)) penetrating to the glass plate 3 are formed using an electrode material and a chemical that can serve as an etchant for the wafer. At this time, the electrode 11 and the wafer 1 are etched by using different chemicals to form the groove 1
2 may be formed. When the electrode 11 is a multilayer film,
The groove 12 may be formed by using a chemical suitable for each electrode film.

The groove 12 formed here is formed in the wafer 1
It cannot be formed at any arbitrary position above, but it is a device pattern formed at a predetermined position, that is, the surface of the wafer 1, TEG (TEG is an abbreviation for Test Elementary Group, and various device characteristics can be evaluated inline. It is necessary to form at a position avoiding the pattern.

Referring to FIG. 5 in detail, in the figure, 1
Reference numeral 4 denotes a device pattern forming portion, and 15 denotes a TEG pattern forming portion. A normal semiconductor does not always have a device pattern formed on the entire surface of the wafer. In many cases, a device pattern is not formed because variations (in-wafer variation) that affect various device characteristics may occur. Further, there is a method of manufacturing a semiconductor having a portion where a device pattern is not formed due to various reasons such as TEG formation near the center of the wafer.

After the above steps are completed, the resist 13 is removed, and the wafer peeling step shown in FIG. 8 in the description of the prior art is started. First, the wafer 1 stuck to the glass plate 3 with the wax 2 is placed in the water tank 7 containing the organic solvent 60 capable of dissolving the wax 2. At this time, in this embodiment, the wax 2 is the organic solvent 60 and the wax 2.
From the contact portion, that is, the outer peripheral portion of the wafer 1 and the outer peripheral portion of the wafer 1 and the groove 12 gradually soak into and melt. Therefore, the portion where the wax 2 and the organic solvent 60 come into contact with each other is remarkably increased as compared with the conventional case, so that the time taken until the wax 2 is completely melted can be shortened. Through the steps described above, the wafer 1 peeled from the glass plate 3 is obtained as shown in FIG.

Thus, according to this embodiment, the wax 2
Since a groove 12 penetrating to the glass plate 3 is provided in a predetermined portion of the wafer 1 attached to the glass plate 3 by using, the wax 2 is dissolved by being immersed in an organic solvent in this state. As a result, the contact area between the organic solvent 60 and the wax 2 is increased, and the time until the wax 2 is completely dissolved is shortened, so that it is possible to reduce wafer cracking without lowering the throughput.

The glass plate 3 is used in the third embodiment.
Although the shape of the groove 12 penetrating up to is rectangular, the shape of the groove 12 is not limited to this, and may be a round shape or the like. It may be different from FIG. However, these elements are
Often defined by wafer size, thickness, and device and TEG pattern placement.

Although wet etching is used as the method of forming the groove 12 in the third embodiment, dry etching may be used instead. Further, the groove 12 may be mechanically formed by a drill or the like. However, in this case, there is a high possibility that defects will occur in the peripheral portion of the wafer in which the groove 12 is formed, so that the groove, the device, and the TEG are not formed.
It is necessary to keep the pattern over a certain distance.

Needless to say, the wafer to be used does not have to be a semiconductor substrate and can be applied to all wafers as long as they are manufactured products requiring the same steps. Also,
In the third embodiment, the groove 12 is formed after the electrode 11 is formed.
However, the electrode 11 may be formed after the groove 12 is formed first. Further, as the organic solvent 60,
By using a resist that can simultaneously dissolve the resist 13 used when forming the groove 12, the step of removing the resist 13 can be omitted, and the manufacturing process can be simplified.

[0034]

As described above, according to the wafer peeling method of the present invention, a force is applied to the reinforcing plate fixed between the wafer and the jig to peel the wafer together with the reinforcing plate from the jig. After that, since the reinforcing plate is selectively dissolved by a solvent, or by making the wafer stuck to the jig with an adhesive into an extremely low temperature state, the adhesive is weakened,
Since this is subjected to ultrasonic cleaning, the wafer can be peeled off from the jig without directly applying mechanical force to the wafer, the wafer is not cracked, and as a result, the yield can be improved. effective.

Further, according to the wafer peeling method of the present invention, since the groove which penetrates the jig is formed in the wafer,
In addition to the peripheral portion of the wafer, the organic solvent permeates not only from the peripheral portion of the groove but also from the peripheral portion of the groove, the dissolution of the adhesive is promoted, and the wafer and the jig can be separated in a short time, leading to a decrease in throughput. In addition, the wafer cracking does not occur, and the yield can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a wafer peeling method according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a wafer peeling method according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view and a plan view showing a state in which a wafer is attached to a glass plate in a wafer peeling method according to a third embodiment of the present invention.

FIG. 4 is a manufacturing process diagram using the wafer peeling method according to the above-described embodiment.

FIG. 5 is a diagram showing an example of a device and a TEG pattern forming unit on the wafer surface.

FIG. 6 is a cross-sectional view and a side view showing a state in which a wafer is attached to a glass plate in a conventional wafer peeling method.

FIG. 7 is a manufacturing process diagram using a conventional wafer peeling method.

FIG. 8 is a diagram showing a conventional wafer peeling method.

FIG. 9 is a diagram showing another conventional wafer peeling method.

[Explanation of symbols]

 1 Wafer 2 Wax 2a Fragile Wax 3 Glass Plate 4a Heat Chuck 4b Heat Chuck 5 Acrylic Plate 6 Acetone Solvent 7 Organic Tank 8 Low Temperature Tank 9 Liquid Nitrogen 10 Ultrasonic Cleaning Tank 11 Electrode 12 Groove 13 Resist 14 Device Pattern Forming Part 15 TEG pattern formation part

Claims (6)

[Claims] 1. A wafer peeling method for peeling a wafer attached to a jig with an adhesive from the jig, wherein a wafer fixed to the jig via a wafer reinforcing plate is stressed to the wafer reinforcing plate. Applied and separated from the jig together with the reinforcing plate, and further soaking the separated wafer reinforcing plate in a solvent,
A wafer peeling method, characterized in that the wafer reinforcing plate is selectively melted and only the wafer is taken out. 2. In a wafer peeling method for peeling a wafer attached to a jig with an adhesive from the jig, the jig attached to the wafer is brought to an extremely low temperature to weaken the adhesive, A method for peeling a wafer, which comprises immersing the attached jig in a cleaning liquid and applying ultrasonic waves to separate the wafer from the jig. 3. A wafer peeling method for peeling a wafer attached to a jig with an adhesive from the jig, wherein the wafer has a groove portion which penetrates the wafer to a predetermined portion and reaches the jig. A wafer peeling method, characterized in that the wafer attached to the jig is immersed in a solvent to dissolve the adhesive, and the wafer is separated from the jig. 4. The wafer peeling method according to claim 3, wherein the groove is formed in a region on the wafer surface where a device pattern is not formed. 5. The wafer peeling method according to claim 3, wherein the groove is formed in a region on the wafer surface where the TEG pattern is not formed. 6. The wafer peeling method according to claim 3, wherein when the wafer is dipped in a solvent, the adhesive and the photosensitive resin used for forming the groove are removed at the same time. Wafer peeling method.