JP5169509B2 - Defect detection method, defect detection system, and light emitting device manufacturing method - Google Patents

Description

  The present invention relates to a method for detecting defects due to poor bonding, defects due to epitaxial growth, defects such as surface scratches, and the like, which occur during the manufacturing process of a light emitting element wafer, a defect detection system, and a method for manufacturing a light emitting element. .

  When manufacturing an ultra-high brightness light emitting device, a quaternary light emitting layer and a light extraction window layer are sequentially grown on the GaAs substrate in the MOCVD reactor and taken out, put into the VPE reactor, and then on the window layer. Further, a thicker window layer is grown to produce a wafer. By increasing the thickness of the window layer, the light extraction effect from the side surface of the light emitting element can be increased. Furthermore, in order to increase the light extraction efficiency, it is necessary to extract the light emitted to the substrate side. However, the light emitted from the light emitting layer to the substrate side by the GaAs substrate as the growth substrate is absorbed by the substrate. Therefore, as disclosed in Patent Document 1, the GaAs substrate is removed by etching, and the epitaxial wafer from which the growth substrate is removed and the GaP substrate which is a transparent substrate are bonded directly or via an adhesive, The light emitted from the light emitting layer can be extracted to the outside from the transparent substrate bonded to the upper window layer through direct bonding or an adhesive.

  However, a void defect that can be confirmed with the naked eye as shown in FIG. 18 or a micro void defect that can be visually recognized with a stereomicroscope as shown in FIG. Many foreign matters at the interface, cracks in the epitaxial layer due to the foreign matters, and defects due to epitaxial growth are observed. Further, defects are taken into the epi layer also due to particles taken in at the time of epitaxial growth.

  There are two possible methods for removing the chip containing these defects. One is a method that performs defect inspection at the wafer stage, removes the defective part found, and then processes the wafer into chips. The other is processing the wafer into chips and then performing defect inspection for each chip. This is a method for removing defective chips by performing the above.

  The former method of performing defect inspection at the wafer stage is easy to detect defects because it can be confirmed at the wafer stage. Also, since the defects are removed and then processed into chips, there is no need for unnecessary chip inspection. There are advantages such as. However, regardless of whether the defective portion exists on the outer peripheral portion of the wafer or not, the non-defective portion may need to be removed in order to remove the defective portion. In addition, since the wafer from which defects have been removed is different in shape and has a smaller area, it cannot be placed on the transfer device in the element manufacturing process, or all suction ports cannot be closed when vacuum suction is performed. There is a problem that it cannot be adsorbed on the surface. Therefore, in reality, it cannot be adopted in the mass production process.

  On the other hand, the method of performing the defect inspection in the latter processed state does not have the above problem. However, since 1 to 20,000 chips are processed for each 2 inch wafer, it is necessary to inspect all the chips, which is very time consuming and burdens the inspector. .

  Further, when a defect is visually removed, depending on the type of defect, it is very difficult to find a defect, and therefore, it is sometimes necessary to change the angle and inspect many times, and the inspection often takes a lot of time. In particular, microvoids have very poor visibility. As the microvoid becomes smaller, the visibility becomes worse. In order to improve the visibility of defects in chip inspection, it is sufficient to increase the amount of illumination used for inspection. However, increasing the amount of light puts a burden on the chip inspector's eyes, and the inspector's inspection is too bright. The possible time is limited to 30 minutes at most. Further, since microvoids and cracks have crystal direction dependency, it is necessary to inspect the chip twice by changing the angle. For this reason, inspecting each chip requires more time, cost, and human resources, and inspecting even a chip that is already known to be defective takes more time and increases costs. . In addition, there is a possibility that an oversight may occur, and a defective product may be judged as a non-defective product.

  In this regard, manufacturing a semiconductor light-emitting element by marking a wafer so that a defective area on the wafer can be identified by a defect inspection method at the wafer stage, then processing the chip and visually removing the chip identified from the mark A method has been proposed (Patent Document 2). However, the visibility of micro voids generated on wafers bonded directly via bonding methods or adhesives is poor, and a specific method for efficiently detecting defects that must be inspected multiple times at different angles. No proposal has been made. In addition, conventionally, after dicing, an inspector visually inspects under a stereomicroscope, and a chip including a defective portion is removed with vacuum tweezers. However, although it is marked by the above method, the work of visually checking 1 to 20,000 chips one by one for each 2 inch wafer is in terms of accuracy and productivity. It becomes a problem.

JP-A-6-302857 JP 2001-85476 A

  The present invention has been made in view of such problems, a chip including defects such as microvoids that are difficult to find visually and can take time, which can be made on a wafer bonded through a direct bonding method or an adhesive, An object of the present invention is to provide a defect detection method and a defect detection system that can be removed accurately and in a short time, and a method for manufacturing a light emitting element.

The present invention has been made in order to solve the above-described problems, and is a direct bonding method or a method for detecting defects in a wafer for light emitting elements bonded through an adhesive, and at least the bonded wafer is A step of detecting a defect in the wafer stage, a step of marking the defect position of the wafer, a step of dicing the marked wafer into a chip, and a step of mechanically detecting the marked chip it that provides a defect detection method according to claim.

In this case, the defect detected by the wafer may be any one or more of a void and a micro void defect due to poor bonding, a foreign substance at the bonding interface and a crack in the epitaxial layer due to the foreign substance, a defect due to epitaxial growth, and a surface flaw. can Ru.

  When bonding is performed through direct bonding or an adhesive, the wafer has microvoids and other micro defects. The defect is much easier to detect in the wafer inspection process than in the inspection process after processing into a chip. And since there are 1 to 20,000 chips that can be processed on one 2 inch wafer, when using the process of visually checking each of these chips one by one, both in terms of time and precision Although it becomes a problem, by having the process of detecting the marked chip | tip mechanically, it becomes a method which can be identified correctly in a short time rather than the process confirmed visually.

In this case, the step of detecting a defect in the wafer stage, it is not preferable in order to detect a defect by using a particle counter.

  Thus, by using a particle counter, a defect can be detected accurately and in a short time, and the inspection burden is reduced. Here, the particle counter is an apparatus for detecting foreign matter and defects on the wafer and inside the transparent substrate by detecting scattered light obtained from the wafer with a CCD when the wafer is irradiated with light.

In this case, the step of marking the defect location, it is not preferable is to mark the defect position using a laser marker.

  If the laser marker is used in this way, a clear and high quality marking that does not disappear can be processed at high speed without contact, and the inspection process can be easily rationalized.

In this case, the step of mechanically detecting the marked chip, it is not preferable in order to detect with the appearance inspection apparatus.

  Thus, by using an appearance inspection apparatus, it becomes a method which can image-process and can specify the marked position. As a specific method, the blue sheet of the expanded chip is applied to a chip appearance inspection device, and the marked portion is subjected to image processing by dividing it into shades, binarization or 256 gradations, and a chip having a portion with a different contrast is mechanically processed. And a method of storing the chip coordinates. With such a method, a correctly marked chip can be detected.

Further, the present invention is a system for detecting defects in a wafer for light emitting elements bonded through a direct bonding method or an adhesive, and at least means for detecting defects in the bonded wafer at the wafer stage; A defect position specifying means for specifying a defect position of the wafer, a marking means for marking the specified defect position, and a chip defect detecting means for mechanically detecting a chip marked after wafer dicing. that provides failure detection system according to.

  In other words, as described above, when bonding is performed through direct bonding or adhesive, the wafer has microvoids and other minute defects. However, the means of inspection at the wafer stage is much easier to detect. And since there are 1 to 20,000 chips that can be machined on a 2 inch wafer, when a means for visually checking these chips one by one is adopted, both in terms of time and accuracy. Although it becomes a problem, it becomes a system which can identify correctly in a short time rather than confirming visually by having the chip | tip defect detection means which detects the marked chip | tip mechanically.

Further, the present invention is that provides a defect detection system comprising a defective chip removal means for mechanically removing the chips further marking the defect position.

  Since the position of the chip including the defective portion is specified by the chip defect detection means for mechanically detecting the marked chip in the defect detection system of the present invention, the machine is used based on the specified coordinate data. Can be removed. In such a case, since the defect can be detected and removed mechanically, the system can be inspected and removed with high accuracy and high throughput without man-hours.

In this case, it means for detecting defects in the wafer stage, it is not preferable that the means used by a particle counter.

  By using the particle counter in this way, a system capable of detecting defects accurately and in a short time is obtained.

In this case, the marking means to mark the defect position, it is not preferable is a means of using a laser marker.

  By using the laser marker in this way, as described above, the system can be effectively marked in that the inspection process can be easily rationalized.

In this case, the chip defect detecting means for mechanically detecting the marked chip, it is not preferable is a means using the visual inspection apparatus.

  By using the appearance inspection apparatus in this way, as described above, the marked chip is subjected to image processing, and a chip having a portion having a different contrast can be mechanically detected accurately and quickly.

The present invention also relates to a method for manufacturing a light emitting device, in which a quaternary light emitting layer and a GaP window layer are sequentially formed on a GaAs substrate by epitaxial growth, and then the GaAs substrate is removed by etching, and the GaP substrate is bonded via an adhesive. After bonding or heat treatment by a direct bonding method, at least the bonded wafer is detected at the wafer stage, and a defect is detected at the wafer, and then a protective film is formed on the back surface of the wafer. after pasting, and processed into chips by dicing the wafer, that provides a method of manufacturing a light emitting device which is characterized in that mechanically detects removing the marked chip.

In this case, the defect detected by the wafer is at least one of a void and a micro void defect due to defective bonding, a foreign substance at the bonding interface and a crack in the epitaxial layer due to the foreign substance, a defect due to epitaxial growth, and a surface flaw. it is Ru can.

  In the method for manufacturing a light emitting device of the present invention, when bonding is performed through direct bonding or an adhesive, the wafer has microvoids and other microdefects, which are inspected after being processed into chips. It is much easier to detect at the wafer stage than to do it. And since there are 1 to 20,000 chips that can be processed on one 2 inch wafer, if these chips are visually checked one by one, there will be a problem in terms of time and accuracy. , By having a chip defect detection method that mechanically detects the marked chip, it is possible to accurately identify in a shorter time than the step of visual confirmation, and a manufacturing method that can manufacture a good product in a short time .

  As described above, the defect detection method, the defect detection system, and the light emitting element manufacturing method according to the present invention are defects that are very poor in visibility and can be caused by epitaxial growth when bonded by direct bonding or adhesive. It is effective for discovering such a chip, and chips including these defects can be mechanically inspected and removed. As a result, inspection accuracy and inspection speed can be improved, which is promising for the problems of improving product accuracy, reducing inspection time, and reducing labor costs.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.
The inventors of the present invention can remove a light emitting element including a defect with very poor visibility generated on a wafer bonded through a direct bonding method or an adhesive more accurately and in a shorter time than a conventional method. In order to develop a defect detection method, a defect detection system, and a method for manufacturing a light-emitting element, intensive studies were conducted.

  As a result, the inventors of the present invention have disclosed a wafer for a light-emitting element bonded through a direct bonding method or an adhesive, at least means for detecting defects in the bonded wafer at a wafer stage, and a defect position of the wafer. A defect detection system comprising: a defect position specifying means for specifying a mark; a marking means for marking the specified defect position; and a chip defect detection means for mechanically detecting a chip marked after dicing the wafer. A defect detection method and a method for manufacturing a light emitting device were found, and the present invention was completed.

  Hereinafter, an embodiment of the defect detection system of the present invention will be described first.

FIG. 1 shows an outline of an example of a defect detection system 1 for a light emitting element wafer bonded together by a direct bonding method or an adhesive according to the present invention. This defect detection system 1 includes an X, Y, Z stage 12, a defect detection camera 13, a defect detection PC 14, a laser mark mechanism 15, a marking control PC 16, a defective chip inspection camera 17, a defective chip detection PC 18, and a defective chip extraction. A device 19 and a defective chip extraction control PC 20 are installed. Such a defect detection system 1 includes a means 2 for detecting defects at a wafer stage of a wafer bonded through a direct bonding method or an adhesive, a defect position specifying means 3 for specifying a defect position of the wafer, and a specification. Marking means 4 for marking the defective position, chip defect detecting means 5 for mechanically detecting the chip marked after wafer dicing, and defective chip removing means for mechanically removing the chip marked at the defective position It is divided into 6 and installed sequentially.
In the following, each means and each device will be described in order by taking as an example a wafer bonded by a direct bonding method.

(Means 2 for detecting defects at the wafer stage of wafers bonded by the direct bonding method)
FIG. 2 is an observation photograph of a wafer bonded by a direct bonding method (hereinafter referred to as a wafer to be inspected). In FIG. 1, the inspection object wafer 11 a is placed on an X, Y, Z stage 12, and a defect is detected by a defect detection camera 13. The means for detecting defects at the wafer stage is not particularly limited, but is preferably means using a particle counter.

(Defect position specifying means 3 for specifying the defect position of the wafer)
The defect position detected by the defect detection camera 13 is placed on the coordinate plane by the defect detection PC 14, and coordinate data (defect map) of the defect position is created. FIG. 3 shows a defect map created by the means. The defect map data is transferred to the marking means control PC 16.

(Marking means 4 for marking the specified defect position)
Based on the defect map data transferred to the marking means control PC 16, the laser mark mechanism 15 marks the defective portion of the wafer 11a to be inspected. The marking means for marking the specified defect position is not particularly limited, but is preferably a means using a laser marker. 4 and 5 show observation photographs of the wafer marked at the defect position by the means.
It should be noted that the conventional means 2 for detecting defects at the wafer stage, the defect position specifying means 3 for specifying the defect position of the wafer, and the marking means for marking the specified defect position. 4, an integrated apparatus in which a series of means is controlled by the host computer 21 as shown in FIG. 6 may be used.

(Chip defect detection means 5 for mechanically detecting chips marked after wafer dicing)
The chip 11b obtained by dicing and expanding the marked wafer is placed on the X, Y, Z stage 12, and the defective chip inspection camera 17 detects the marked chip. The defective chip detection PC 18 processes camera information and creates coordinate data of the position of the chip including the defect. The chip defect detection means 5 for mechanically detecting the marked chip is not particularly limited, but is preferably a means using an appearance inspection apparatus. As a specific means, the blue chip sheet of the expanded chip is applied to a chip appearance inspection device, and the marked portion is subjected to image processing by dividing it into shades, binarization or 256 gradations, and a chip having a portion with a different contrast is mechanically processed. And means for storing the chip coordinates. Thus, the coordinate data of the chip including the defect is transferred to the defective chip extraction control PC 20.

(Defect chip removal means 6 for mechanically removing the chip marked at the defect position)
The chip on the stage 12 at the position where the defective chip is located is pushed up by the coordinate data of the defective chip transferred to the defective chip sampling control PC 20. The protruding chip is removed by the extracting device 19. In addition, you may use what integrated the chip | tip defect detection means 5 and the defect chip | tip removal means 6. FIG.

  The defect detection system 1 described above is effective for finding defects with very poor visibility that can be formed during direct bonding, defects due to epitaxial growth, and the like, and mechanically inspecting and removing chips containing these defects. It is a system that can. By using this defect detection system 1, it is possible to improve the accuracy and processing speed of the work of removing defective chips that have been removed visually, and to automatically remove chips containing defects.

  Next, an embodiment of the defect detection method of the present invention will be described by taking a wafer bonded by a direct bonding method as an example.

FIG. 7 shows an example of a flowchart of a defect detection method for a light emitting element wafer bonded by the direct bonding method according to the present invention. In this defect detection method, a wafer 101 bonded by a direct bonding method is detected at a wafer stage 101, a wafer is marked at a defect position 102, and the marked wafer is diced and processed into a chip. A defect can be detected by sequentially performing the process 103 and the process 104 of mechanically detecting the marked chip.
Hereinafter, each process will be described sequentially.

(Step 101 for detecting defects at the wafer stage of directly bonded wafers)
Defects are detected at the wafer stage for wafers bonded by the direct bonding method. The method for detecting defects at the wafer stage is not particularly limited, but a method for detecting defects using a particle counter is preferred. Further, the detected defect is not particularly limited, and examples thereof include voids and microvoid defects due to poor bonding, foreign matter at the bonding interface and cracks in the epitaxial layer due to the foreign matter, defects due to epitaxial growth, and surface scratches. The detected defect is processed by a PC to create a defect map.

(Step 102 for marking the defect position of the wafer)
Based on the defect map created by the previous process, marking is performed on the detected defect position of the wafer. A method for marking a defect position is not particularly limited, but a method for marking a defect position using a laser marker is preferable.

(Step 103 of dicing the marked wafer into a chip)
The marked wafer is diced and processed into chips. In the subsequent process, an adhesive seal is attached as a protective film on the back surface of the wafer so that the chips formed on one wafer can be detected collectively, and the chips are processed so as not to cut the seal.

(Step 104 of mechanically detecting the marked chip)
After the wafer dicing, the marked chip is mechanically detected. A method of mechanically detecting the marked chip is not particularly limited, but a method of detecting using a visual inspection apparatus is preferable. As an example of a specific method, a blue sheet of an expanded chip is applied to a chip appearance inspection device, and the marked portion is subjected to image processing by dividing it into shades, binarization or 256 gradations, and a chip having a portion with a different contrast is obtained. There is a means for mechanically detecting and storing the chip coordinates.

  The above defect detection methods are effective for finding defects with very poor visibility that can be made during direct bonding and defects caused by epitaxial growth, and mechanically inspecting and removing chips that contain these defects It is a method that can be. By using this defect detection method, it is possible to reduce labor costs and shorten the time for the work that the inspector has inspected visually one by one. More chip inspection can be performed. Moreover, since it detects mechanically, there exists an effect which prevents an oversight.

  Next, an embodiment of a method for manufacturing a light emitting device according to the present invention will be described by taking a wafer bonded by a direct bonding method as an example.

  An example of a method for manufacturing a light emitting device of the present invention includes a step of sequentially forming a quaternary light emitting layer and a GaP window layer on a GaAs substrate by epitaxial growth, a step of etching and removing the GaAs substrate, and a heat treatment of the GaP substrate by a direct bonding method. A step of detecting a defect in the wafer stage, a step of marking a defect position on the wafer, a protective film is attached to the back surface of the wafer, and then the wafer is diced into a chip. The light emitting device is manufactured by sequentially performing the processing step and the step of mechanically detecting and removing the marked chip. FIG. 8 shows an example of a flowchart of finer steps of the method for manufacturing a light emitting device according to the present invention. FIG. 9 is a conceptual diagram of a light emitting device manufactured by the manufacturing method of the present invention.

  The light-emitting element manufactured by the manufacturing method of the present invention has a light-emitting layer portion, and is a first layer to be bonded that is defined so that the first main surface side is p-type and the second main surface side is n-type. The light extraction side electrode is formed so as to partially cover the main surface. The light emitting layer portions 53a, 53b, and 53c are made of a group III-V compound semiconductor, and each of the n-type clad layer 53a, the active layer 53b, and the p-type clad layer each made of AIGalnP having a composition that lattice matches with GaAs. 53c has a double heterostructure stacked in this order. An n-type transparent element substrate 52a made of a III-V group compound semiconductor having a band gap energy larger than that of the active layer is bonded to the second main surface of the bonding target layer.

  The transparent element substrate is an n-type GaP single crystal substrate 52a, and the entire surface of the second main surface is covered with a back electrode 51a. The light extraction side electrode 51b is formed substantially at the center of the first main surface of the current diffusion layer 52b, and the region around the light extraction side electrode is a light extraction region from the light emitting layer portion. A bonding pad 54 made of Au or the like for bonding the electrode wire 55 is disposed at the center of the light extraction side electrode.

The light emitting layer portion is grown by the MOVPE method and is represented by a composition formula (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1). Among compound semiconductors, the compound semiconductor is composed of a compound semiconductor having a composition lattice-matched with GaAs. Specifically, the light emitting layer portion is made of a non-doped (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 0.55, 0.45 ≦ y ≦ 0.55) mixed crystal. an active layer 53b, p-type _{(Al x Ga 1-x)} Z In 1-Z P ( where, x <z ≦ 1) and the p-type cladding layer 53c formed of, n-type _{(Al x Ga 1-x)} Z In _It has a structure sandwiched between n-type cladding layers 53a made of _1-ZP (where x <z ≦ 1). In the light emitting device of FIG. 9, a p-type AlGaInP cladding layer 53c is disposed on the light extraction side electrode side 51b, and an n-type AlGaInP cladding layer 53a is disposed on the back electrode side 51a. Therefore, the energization polarity is positive on the light extraction side electrode side 51b.

  On the other hand, the current spreading layer 52b is formed as a p-type GaP layer using Zn as a dopant. The dopant may be Mg, or a combination of Zn and Mg. The current diffusion layer is formed by a hydride vapor phase epitaxy (HVPE) method, and the thickness of the current diffusion layer is, for example, 5 μm to 200 μm (for example, 150 μm). In addition, an n-type GaP connection layer may be formed between the current spreading layer and the light emitting layer by the MOVPE method in a form following the light emitting layer.

  Next, the manufacturing method of the light-emitting element of the present invention will be described with reference to the flowchart of FIG. 8 taking a wafer bonded by a direct bonding method as an example.

(Process 201 for preparing GaAs single crystal substrate)
An n-type GaAs single crystal substrate is prepared as a growth single crystal substrate. Since the substrate has a band gap energy smaller than that of the active layer, it is opaque to the luminous flux from the light emitting layer portion.

(Step 202 of sequentially forming a quaternary light emitting layer and a GaP window layer by epitaxial growth)
1 μm n-type cladding layer 53a (n-type dopant is Si) each made of (Al _x Ga _1-x ) _y In _1-y P as a light emitting layer on the first main surface of the substrate, 0.6 μm active Layer 53b (non-doped) and 1 μm p-type cladding layer 53c (p-type dopant is Mg: C from organometallic molecules can also contribute as a p-type dopant) are epitaxially grown in this order. Note that an n-type GaAs buffer layer and an etch stop layer made of AlInP may be grown before the light emitting layer portion is grown.

Epitaxial growth of each of these layers is performed by a known MOVPE method. As source gases that are source components of Al, Ga, In (indium), and P (phosphorus), an Al source gas (for example, trimethylaluminum (TMAl), triethylaluminum (TEAl)), a Ga source gas (for example, trimethylgallium) (TMGa), triethylgallium (TEGa)), In source gas (for example, trimethylindium (TMIn), triethylindium (TEIn)), P source gas (for example, trimethylphosphorus (TMP), triethylphosphorus (TEP), phosphine ( PH ₃ )) and the like.

A current diffusion layer 52b made of p-type GaP is epitaxially grown by the HVPE method. Specifically, in the HVPE method, GaCl, which is a group III element, is heated and held at a predetermined temperature in a container, and hydrogen chloride is introduced onto the Ga, thereby causing GaCl by the reaction of the following formula (1). And is supplied onto the substrate together with the H ₂ gas that is a carrier gas. The growth temperature is set to, for example, 640 ° C. or more and 860 ° C. or less.

Further, P which is a group V element supplies PH ₃ onto the substrate together with H ₂ which is a carrier gas. Furthermore, Zn which is a p-type dopant is supplied in the form of DMZn (dimethyl Zn). GaCl is excellent in reactivity with PH _3, and the current diffusion layer can be efficiently grown by the reaction of the following formula (2). In some cases, a connection layer made of p-type GaP is heteroepitaxially grown on the light emitting layer portion by MOVPE before the growth of p-type GaP by HVPE.

  Through the steps so far, the compound semiconductor growth layer is epitaxially grown on the GaAs single crystal substrate by two kinds of vapor phase growth methods to form an intermediate stacked body. In the intermediate laminate, the light emitting layer portion and the current diffusion layer are layers to be bonded, and the GaAs single crystal substrate is a non-elementized portion.

(Step 203 of removing GaAs substrate by etching)
The GaAs single crystal substrate is removed. The removal is performed by grinding from the second main surface side of the GaAs single crystal substrate to reduce the substrate thickness to some extent, and then a first etching solution (for example, ammonia / hydrogen peroxide mixed solution) having selective etching property with respect to GaAs. ) Is used to etch away the GaAs single crystal substrate.

(Step 204 in which the GaP substrate is heat-treated by a direct bonding method and bonded)
An n-type GaP substrate 52a is attached to the light emitting layer side of the intermediate laminate. At the time of bonding, the temperature is raised to 400 ° C. or higher and 700 ° C. or lower, and bonding heat treatment is performed. In that case, you may make it pressurize at the time of bonding heat processing. Note that an InGaP intermediate layer may be epitaxially grown on the first main surface of the n-type GaP single crystal substrate before bonding. Epitaxial growth of the InGaP intermediate layer is performed by the MOVPE method in the same manner as the light emitting layer portion. Through the above steps, a semiconductor wafer for manufacturing a light emitting device is completed.

(Step 205 of detecting defects at the wafer stage of the bonded wafer)
The bonded wafer is detected for defects at the wafer stage. The method for detecting defects is not particularly limited, but a method using a particle counter is preferable. In this case, the defect to be detected is not particularly limited, but a void and a micro void defect due to poor bonding, a foreign substance at the bonding interface and a crack in the epitaxial layer due to the foreign substance, a defect due to epitaxial growth, a surface flaw, and the like can be considered.

(Step 206 of marking the defect position of the wafer)
The defect position detected in the wafer stage is marked. The marking method is not particularly limited, but a method using a laser marker is preferable.

(Electrode formation by vacuum deposition and protective film application step 207)
The light extraction side electrode and the back surface electrode 51a are formed on each chip region of the semiconductor wafer for manufacturing a light emitting element by vacuum deposition. Further, a bonding pad 54 is disposed on the light extraction side electrode 51b, and an electrode fixing sintering process is performed at an appropriate temperature. Further, in preparation for dicing in the next process, a seal is attached as a protective film on the rear surface of the wafer. The seal is affixed so that the chips formed on one wafer can be collectively detected in a process after dicing.

(Process 208 for dicing the wafer into chips)
This wafer is diced into each chip. When dicing, the elements are separated so as not to cut the sticker attached to the back surface of the wafer.

(Step 209 for mechanically detecting and removing the marked chip)
The marked chip is mechanically detected and removed. A method of mechanically detecting the marked chip is not particularly limited, but a method of detecting using a visual inspection apparatus is preferable. As an example of a specific method, a blue sheet of an expanded chip is applied to a chip appearance inspection device, and the marked portion is subjected to image processing by dividing it into shades, binarization or 256 gradations, and a chip having a portion with a different contrast is obtained. There is a means for mechanically detecting and storing the chip coordinates. It is also possible to remove the defective chip with a machine based on the coordinate data of the defective chip.

(Wire bonding and resin mold forming step 210)
The back electrode of the diced chip is fixed to a terminal electrode (not shown) that also serves as a support using a conductive paste such as an Ag paste, which is made of Au in a form straddling the bonding pad 54 and another terminal electrode. The final light-emitting element is obtained by bonding the wire 55 and further forming a resin mold.

The above light-emitting device manufacturing method is effective for finding defects with very poor visibility that can be made during direct bonding and defects caused by epitaxial growth, and mechanically inspecting and removing chips containing these defects This is how you can do it. By using this light emitting device manufacturing method, it is possible to automatically remove all defective chips that have been removed with the naked eye, saving time and labor costs, and reducing defective products. Since the probability of mixing can be reduced, a high-quality product can be provided at a low price.
Further, the present invention is not limited to the bonding by the direct bonding method, but also when a transparent semiconductor substrate such as GaP or a glass substrate is bonded through an adhesive made of BCB (B-stage bisbenzocyclobutene) or epoxy. The defect detection system, the defect detection method, and the light emitting element manufacturing method of the invention can be applied.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
(Example)
A direct bonding wafer having a diameter of 50 mm is inspected by a film inspection apparatus (CSI-7000) manufactured by Takano Co., Ltd., voids and microvoid defects due to poor bonding, foreign matter at the bonding interface, cracks in the epitaxial layer due to the foreign matter, defects due to epitaxial growth, Surface flaws were acquired with XY coordinate data. Based on the defect data XY coordinates, a laser mark was made on the defect with a “YAG laser (HSL-5500: wavelength 355 nm)” manufactured by HOYA. The laser head was also used for a product equipped with a Takano YAG laser (UVTS-4300: wavelength 266 nm). FIG. 10 shows the state of the marked chip.

  The number of chips diced from the wafer was 20,000. The state in which these chips were inspected by using “N-face appearance inspection apparatus HS-256E” manufactured by Hubrain was as shown in FIGS. Further, FIG. 13 shows a state in which the back surface of the chip was inspected using a “chip appearance inspection apparatus” manufactured by MTEC, FIG. 14 shows a result of extracting only the electrodes, and FIG. 15 shows a result of extracting only the laser marks. Further, the inspection using the “chip appearance inspection device” manufactured by Optsystem Co., Ltd. is as shown in FIGS. With any visual inspection apparatus, the marked portion could be confirmed, and the marked chip could be immediately selected. The time required for selecting defective chips by wafer defect inspection, laser marking and appearance inspection was about 1 hour.

(Comparative example)
A directly bonded wafer (diameter 50 mm) having a diameter of 50 mm was divided by dicing without marking, and then the defects were visually inspected to select defective chips. In this case, about 5 hours were required for chip inspection on the entire wafer surface. Thus, in the case of the comparative example, the time required for selecting the chips per wafer was about five times as long as that of the example because the visibility was poor and the inspection took time.

  As described above, the time required for selecting a chip per wafer is about 5 times as long as that of the embodiment because the visibility is poor and the inspection takes time in the case of the comparative example, and the defective product may be overlooked. there were.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

1 schematically shows an example of a defect detection system for a light emitting device wafer bonded by a direct bonding method according to the present invention. It is the observation photograph of the wafer bonded together by the direct joining method. It is a defect map created based on the defect position detected by the defect camera. It is an observation photograph of a wafer marked at a defect position. It is an observation photograph of a wafer marked at a defect position. 1 schematically shows an apparatus in which a defect detection means, a defect position specifying means, and a marking means in a wafer stage are integrated. 3 shows an example of a flowchart of a defect detection method for a light emitting element wafer bonded by a direct bonding method according to the present invention. 1 shows an example of a flowchart of a method for manufacturing a light emitting device according to the present invention. 1 schematically shows an example of a light-emitting element manufactured by the method for manufacturing a light-emitting element according to the present invention. It is the photograph of the marked chip | tip in the Example, and the observation photograph of the chip | tip which was diced and expanded. It is a mode that it test | inspected using the "N surface appearance inspection apparatus HS-256E" by Hue Brain in an Example. It is a mode that it test | inspected using the "N surface appearance inspection apparatus HS-256E" by Hue Brain in an Example. It is a mode that the chip | tip back surface was test | inspected using the "chip external appearance inspection apparatus" by the MTEC company in an Example. It is a mode that only the electrode was extracted using "the chip | tip appearance inspection apparatus" by MTEC in an Example. It is a mode that only the laser mark was extracted using the "chip appearance inspection apparatus" by MTEC in an Example. It is a mode that it test | inspected using the "chip external appearance inspection apparatus" by the opt system company in an Example. It is a mode that it test | inspected using the "chip external appearance inspection apparatus" by the opt system company in an Example. It is a state of a void defect formed on the interface bonded through a direct bonding method or an adhesive. It is a state of the microvoid defect visually recognized with a stereomicroscope.

Explanation of symbols

1 ... Defect detection system,
2. Means for detecting defects at the wafer stage of wafers bonded by a direct bonding method,
3 ... Defect position specifying means for specifying the defect position of the wafer,
4. Marking means for marking the specified defect position,
5 ... Chip defect detecting means for mechanically detecting a chip marked after wafer dicing,
6 ... Defective chip removing means for mechanically removing the chip marked at the defect position,
11a: Inspected wafer, 11b: Expanded chip,
12 ... X, Y, Z stage, 13 ... Defect detection camera, 14 ... Defect detection PC,
15 ... Laser mark mechanism, 16 ... PC for marking control,
17 ... defective chip inspection camera, 18 ... PC for detecting defective chip,
19 ... defective chip extraction device, 20 ... defective chip extraction control PC,
21 ... Host computer,
51a ... back electrode, 51b ... light extraction side electrode, 52a ... n-GaP,
52b ... p-GaP, 53a ... n-AlGaInP, 53b ... i-AlGaInP,
53c ... p-AlGaInP, 54 ... bonding pad, 55 ... wire.

Claims (10)

A method for detecting a defect in a wafer for light emitting elements bonded through a direct bonding method or an adhesive, wherein at least a step of detecting a defect in the bonded wafer at a wafer stage, and a defect position on the wafer A step of marking, a step of dicing the marked wafer into a chip, a step of placing the expanded chip on the stage and mechanically detecting the marked chip, and a position where the marked chip is present A step of pushing up the chip on the stage and removing the protruding chip, and the step of mechanically detecting the marked chip is performed by using a blue sheet of the chip expanded using an appearance inspection device. The image of the marked part is processed by the appearance inspection device, and the contrast is different. Defect detection method characterized by mechanically detecting the chips with.   The defect detected by the wafer is any one or more of a void and a micro void defect caused by defective bonding, a foreign substance at a bonding interface and a crack in an epitaxial layer due to the foreign substance, a defect caused by epitaxial growth, and a surface flaw. The defect detection method according to claim 1.   3. The defect detection method according to claim 1, wherein the step of detecting a defect at the wafer stage detects the defect using a particle counter.   4. The defect detection method according to claim 1, wherein the step of marking the defect position is to mark the defect position using a laser marker. 5. A system for detecting a defect in a wafer for light emitting elements bonded through a direct bonding method or an adhesive, and at least means for detecting a defect in the bonded wafer at a wafer stage, and a defect position of the wafer Defect position specifying means for specifying, marking means for marking at the specified defect position, chip defect detecting means for placing the expanded chip after wafer dicing on the stage, and mechanically detecting the marked chip, and marking The chip on the stage at the position where the chip is located is composed of a defective chip removing means for removing the protruding chip , and the chip defect detecting means is a blue color of the expanded chip using an appearance inspection device. The sheet is applied to the appearance inspection device, and the marked portion is subjected to image processing. , Defect detection system, characterized in that for mechanically detecting the chip with a different portion of the contrast.   6. The defect detection system according to claim 5, further comprising defective chip removing means for mechanically removing the chips marked at the defect positions.   7. The defect detection system according to claim 5, wherein the means for detecting a defect at the wafer stage is a means using a particle counter.   The defect detection system according to any one of claims 5 to 7, wherein the marking means for marking the defect position is a means using a laser marker. A method of manufacturing a light emitting device, in which a quaternary light emitting layer and a GaP window layer are sequentially formed on a GaAs substrate by epitaxial growth, and then the GaAs substrate is removed by etching, and the GaP substrate is bonded with an adhesive or directly bonded. After the heat treatment is applied and bonded, at least the bonded wafer is detected at the wafer stage, marked at the defect position of the wafer, and then a protective film is applied to the wafer back surface. Is processed into chips, the expanded chip is placed on the stage, the blue sheet of the expanded chip using the visual inspection device is applied to the visual inspection device, the marked portion is image processed, and the contrast is different. The marked chip by mechanically detecting the chip with Mechanically detected, marked chip pushed up above the chip on the stage of a location, the method of manufacturing the light emitting device characterized by the removal of chips issued projecting.   The defect detected by the wafer is any one or more of a void and a micro void defect caused by defective bonding, a foreign substance at a bonding interface and a crack in an epitaxial layer due to the foreign substance, a defect caused by epitaxial growth, and a surface flaw. The manufacturing method of the light emitting element of Claim 9.

Images