Method for removing poor bonding portion of bonded wafer and method for manufacturing bonded wafer

Abstract

The present invention is a method for removing a poor bonding portion of a bonded wafer having a light-emitting element structure provided with an active layer composed of (AlyGa1-y) xIn1-xP (0.4 < = x < = 0.6, 0 < = y < = 0.5), and a method for removing a poor bonding portion of a bonded wafer having a light-emitting element structure provided with an active layer composed of (AlyGa1-y) xIn1-xP (0.4 < = x < = 0.6, 0 < = y < = 0.5), the present invention relates to a method for bonding a light-emitting element structure to a transparent substrate through which light having an emission wavelength is transmitted, and a heat-curable bonding member is cured to bond the light-emitting element structure to the transparent substrate through which light having the emission wavelength is transmitted, characterized in that the bonding wafer is introduced into a plasma atmosphere to selectively destroy and remove the poor bonding portion where the heat-curable bonding member is not sufficiently cured. As a result, provided is a method for removing a poor bonding portion of a bonded wafer in which a light-emitting element structure having an AlGaInP-based active layer and a transparent substrate are bonded via a thermosetting bonding member, said method being capable of removing a poor curing portion of the bonded wafer without using a means such as measurement.

Description

Technical Field

[0001] The present invention relates to a method for removing a poorly bonded portion of a bonded wafer and a method for manufacturing the bonded wafer, and in particular to a method for removing a poorly bonded portion of a bonded wafer having a light emitting element structure and a method for manufacturing the bonded wafer. Background Art

[0002] In order to realize a micro light emitting diode display (Micro LED Display), a technology has been disclosed for using laser lift-off (LLO) to peel off the LED from the starting substrate and then transfer it to a packaging substrate and then to a driving substrate (Patent Document 1). However, these technologies are only for GaN-based LEDs, and there are still few technologies involving μ-LEDs using AlGaInP-based LEDs.

[0003] In order to realize a micro LED element in an AlGaInP-based LED through the LLO process, it is necessary to transfer it to a sapphire substrate. Regarding the technology of transferring an AlGaInP-based LED to a sapphire substrate, for example, prior art such as Patent Document 2 is disclosed. However, there is no prior art disclosed for a countermeasure against the situation where poor curing occurs in some parts.

[0004] If oxygen is present during curing, benzocyclobutene (BCB) cannot be fully cured under the conditions of the designed temperature and time, which will cause poor curing. Therefore, curing is usually carried out in a vacuum atmosphere or a nitrogen atmosphere. However, the process of overlapping two wafers, pressing and heating them sometimes leaves oxygen at the bonding interface due to its characteristics.

[0005] For example, if the surface after BCB coating has large irregularities and oxygen cannot be fully removed before bonding or cannot be fully exhausted, oxygen will remain. The remaining oxygen will cause poor cross-linking of BCB and further cause poor curing.

[0006] Although FTIR and other methods can be used to inspect and confirm the curing rate of the poorly cured BCB part, the poorly cured part will continue to peel off in the subsequent process, and the peeled fragments will damage the good part or contaminate the equipment. Therefore, the poor part needs to be removed before entering the subsequent process.

[0007] However, the prior art does not disclose the detection and removal of the poorly cured portion.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent document 1: Japanese Patent Application Publication No. 2020-521181.

[0011] Patent document 2: Japanese Patent Application Publication No. 2022-013203. Summary of the invention

[0012] 1. Technical issues to be resolved

[0013] The present invention is implemented in view of the above-mentioned technical problems, and its purpose is to provide a method for removing the poorly bonded portion of a bonded wafer, which can remove the poorly cured portion in the bonded wafer without utilizing measurement or the like. The bonded wafer bonds a light-emitting element structure having an active layer of an AlGaInP system to a transparent substrate via a thermosetting bonding component; the present invention also aims to provide a method for manufacturing the bonded wafer.

[0014] (II) Technical solution

[0015] The present invention is implemented to achieve the above-mentioned object and provides a method for removing a poorly bonded portion of a bonded wafer, wherein the bonded wafer has a light emitting element structure, wherein the light emitting element structure has (Al y Ga 1-y ) x In 1-x The active layer is composed of P (0.4≤x≤0.6, 0≤y≤0.5), and the bonded wafer is bonded to a transparent substrate that transmits light of the luminous wavelength by curing a thermosetting bonding component. The removal method is characterized in that the poor bonding portion caused by insufficient curing of the thermosetting bonding component is selectively destroyed by introducing the bonded wafer into a plasma atmosphere, thereby removing the poor bonding portion.

[0016] By introducing the bonded wafer into the plasma atmosphere as described above, the insufficiently cured poorly bonded portion can be selectively destroyed, and the poorly bonded portion can be removed in one process without requiring two or more steps of detecting the poorly bonded portion and removing the detected portion.

[0017] In this case, it is preferable that the thermosetting bonding member be benzocyclobutene.

[0018] By using benzocyclobutene as a thermosetting bonding member, it is possible to more reliably remove a poorly bonded portion.

[0019] Furthermore, it is preferable that the transparent substrate be sapphire or quartz.

[0020] As the transparent substrate, the above-mentioned substrates can be used appropriately, and in particular, a substrate having high transparency to the LLO laser can be selected.

[0021] Furthermore, the plasma atmosphere is preferably a plasma atmosphere formed by plasmafiing one or more gases including oxygen, nitrogen, argon, helium, and hydrogen in a plasma generator having a barrel-type or parallel-plate electrode structure.

[0022] By adopting such a plasma atmosphere, the defective portion can be removed more easily and more reliably.

[0023] Furthermore, it is preferable that the device for generating the plasma atmosphere is a RIE (Reactive Ion Etching) device, an ICP (Inductively Coupled Plasma) device, a plasma CVD device, an ashing device, or a sputtering device.

[0024] As a device for generating the atmosphere used in the present invention, the above-mentioned plasma generating device can be used appropriately.

[0025] In addition, the present invention provides a method for manufacturing a bonded wafer, which includes the following steps: preparing an epitaxial wafer and a transparent substrate, wherein the epitaxial wafer has a light-emitting element structure, and the light-emitting element structure has (Al y Ga 1-y ) x In 1-x P(0.4≤x≤0.6, 0≤y≤0.5), the transparent substrate transmits light of the emission wavelength in the light-emitting element structure; the epitaxial wafer and the transparent substrate are bonded together via a thermosetting bonding member, and the thermosetting bonding member is cured to thereby bond them to form a bonded wafer, wherein the manufacturing method further comprises: after curing the thermosetting bonding member, the bonded wafer is introduced into a plasma atmosphere to selectively destroy a poorly bonded portion where the thermosetting bonding member is insufficiently cured, thereby removing the poorly bonded portion.

[0026] The method for manufacturing a bonded wafer can remove the poorly bonded portion by selectively destroying the poorly bonded portion that is insufficiently cured by introducing the bonded wafer of the thermosetting bonding member into a plasma atmosphere. Therefore, it is a method for manufacturing a bonded wafer that can remove the poorly bonded portion in one process, and does not require more than two steps of detecting the poorly bonded portion and removing the detected portion.

[0027] In this case, it is preferable that the thermosetting bonding member be benzocyclobutene.

[0028] By using benzocyclobutene as a thermosetting bonding member, a bonded wafer from which bonding failure portions are more reliably removed can be manufactured.

[0029] Furthermore, it is preferable that the transparent substrate be sapphire or quartz.

[0030] As the transparent substrate, the above-mentioned substrates can be used appropriately, and in particular, a substrate having high transparency to the LLO laser can be selected.

[0031] Furthermore, the plasma atmosphere is preferably a plasma atmosphere formed by plasmafiing one or more gases including oxygen, nitrogen, argon, helium, and hydrogen in a plasma generator having a barrel-type or parallel-plate electrode structure.

[0032] By using such a plasma atmosphere, a bonded wafer from which defective portions are removed can be manufactured more easily and more reliably.

[0033] Furthermore, it is preferable that the device for generating the plasma atmosphere is a RIE (Reactive Ion Etching) device, an ICP (Inductively Coupled Plasma) device, a plasma CVD device, an ashing device, or a sputtering device.

[0034] In the method for manufacturing a bonded wafer of the present invention, as a device for generating a plasma atmosphere, the plasma generating device described above can be used appropriately.

[0035] (III) Beneficial effects

[0036] The method for removing the poorly bonded portion of a bonded wafer and the method for manufacturing a bonded wafer of the present invention introduce a bonded wafer formed by bonding a light-emitting element structure having an active layer of an AlGaInP system to a transparent substrate via a thermosetting bonding member into a plasma atmosphere, selectively destroying the poorly bonded portion that is insufficiently cured, and removing the poorly bonded portion in one treatment, without the need for more than two steps of detecting the poorly bonded portion and removing the detected portion. That is, the poorly cured portion in the bonded wafer can be removed without using a measurement technique, so the productivity is improved, and the yield of products such as micro LEDs manufactured from the bonded wafer is also improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic cross-sectional view of a part of the process of manufacturing a bonded wafer which is applicable to the method of removing a poorly bonded portion of a bonded wafer of the present invention.

[0038] Figure 2 It is a schematic cross-sectional view showing another part of the process of manufacturing a bonded wafer which can be applied to the method of removing a poorly bonded portion of a bonded wafer of the present invention.

[0039] Figure 3 It is a schematic cross-sectional view showing another part of the process of manufacturing a bonded wafer which can be applied to the method of removing a poorly bonded portion of a bonded wafer of the present invention.

[0040] Figure 4 It is a graph which shows the results of Examples and Comparative Examples. DETAILED DESCRIPTION

[0041] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0042] One aspect of the present invention is a method for removing a poorly bonded portion of a bonded wafer, wherein the bonded wafer has a light emitting element structure, wherein the light emitting element structure has (Al y Ga 1-y ) x In 1-x The active layer is composed of P (0.4≤x≤0.6, 0≤y≤0.5), and the bonded wafer is bonded to a transparent substrate that transmits light of the luminous wavelength by curing a thermosetting bonding component. The removal method is characterized in that the poor bonding portion caused by insufficient curing of the thermosetting bonding component is selectively destroyed by introducing the bonded wafer into a plasma atmosphere, thereby removing the poor bonding portion.

[0043] In addition, another aspect of the present invention is a method for manufacturing a bonded wafer, which includes the following steps: preparing an epitaxial wafer and a transparent substrate, wherein the epitaxial wafer has a light emitting element structure, wherein the light emitting element structure has (Al y Ga 1-y ) x In 1-x P(0.4≤x≤0.6, 0≤y≤0.5), the transparent substrate transmits light of the emission wavelength in the light-emitting element structure; the epitaxial wafer and the transparent substrate are bonded together via a thermosetting bonding member, and the thermosetting bonding member is cured to thereby bond them to form a bonded wafer, wherein the manufacturing method further comprises: after curing the thermosetting bonding member, the bonded wafer is introduced into a plasma atmosphere to selectively destroy a poorly bonded portion where the thermosetting bonding member is insufficiently cured, thereby removing the poorly bonded portion.

[0044] Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. Hereinafter, the aspects of the present invention will be described by taking the first to fourth embodiments as examples.

[0045] (First embodiment)

[0046] First, the first embodiment will be described. The first embodiment is an example in which a plasma generator is used as an ashing device.

[0047] First, a bonding wafer is prepared. The bonding wafer has a light emitting element structure. The light emitting element structure has (Al y Ga 1-y ) x In 1-x P (0.4 ≤ x ≤ 0.6, 0 ≤ y ≤ 0.5), and the bonded wafer is cured by a thermosetting bonding member to bond the light emitting element structure to a transparent substrate that transmits light of the emission wavelength. The preparation of the above-mentioned bonded wafer can be implemented by the following steps: a step of preparing an epitaxial wafer and a transparent substrate, the epitaxial wafer having a light emitting element structure, the light emitting element structure having (Al y Ga 1-y ) x In 1-x The active layer is composed of P (0.4≤x≤0.6, 0≤y≤0.5), and the transparent substrate transmits the light of the emission wavelength in the light-emitting element structure; the epitaxial wafer and the transparent substrate are bonded by a thermosetting bonding member, and the thermosetting bonding member is cured to bond them to form a bonded wafer. This bonded wafer can be specifically manufactured in the following manner.

[0048] First, if Figure 1 As shown, an etch stop layer 12 is epitaxially grown on a starting substrate 11 of a first conductivity type, for example, GaAs. The etch stop layer 12 can be formed by, for example, stacking a first conductivity type GaAs buffer layer and then epitaxially growing a first conductivity type GaAs buffer layer. x In 1-x A first etching layer of P (0.4≤x≤0.6) is grown with a thickness of, for example, 0.1 μm, and a second etching layer of, for example, first conductivity type GaAs is grown with a thickness of, for example, 0.1 μm. Further, an epitaxial wafer 20 having a light emitting element structure 18 as an epitaxial functional layer is prepared. The epitaxial functional layer is sequentially grown with, for example, first conductivity type (Al y Ga 1-y ) x In 1-x The first cladding layer 13 is grown with a thickness of, for example, 1.0 μm, and is made of, for example, undoped (Al y Ga 1-y ) x In 1-x P (0.4≤x≤0.6, 0≤y≤0.5) active layer 14, for example, second conductivity type (Al y Ga1-y ) x In 1-x The second cladding layer 15 is grown with a thickness of, for example, 1.0 μm, and the second conductivity type Ga x In 1-x A P (0.5≤x≤1.0) intermediate layer (not shown) is grown with a thickness of, for example, 0.1 μm, and a second conductivity type GaP window layer 16 is grown. The portion from the first cladding layer 13 to the second cladding layer 15 is referred to as a double heterogeneous (DH) structure portion ( Figure 1 ).

[0049] The aforementioned film thickness is only an example, and the film thickness is only a parameter that should be changed according to the operating specifications of the device, and is not limited to the film thickness described here. Although the first cladding layer 13 and the second cladding layer 15 are both 1.0 μm, for micro LEDs, even if the rated current density is lower than that of large-sized discrete LEDs and the film thickness is thinner than this, the function as a cladding layer will not be impaired.

[0050] In addition, since the electrode is formed in a form connected to the first cladding layer 13, considering the metal diffusion when forming an ohmic contact, the first cladding layer 13 is suitable to have a thickness of 0.6 μm or more. As long as it is above this thickness, any thickness can be selected. However, if it becomes too thick, it will not only become the main cause of cost increase, but also become prone to the reduction of luminous efficiency when driven by rated current or the reduction of yield caused by increased warping of the wafer. Therefore, the thickness is preferably set to 10 μm or less.

[0051] In addition, when the second cladding layer is P-type, since the effective mass of the hole is large, even if the second cladding layer 15 is, for example, about 0.2 μm thick, it can still function in the same manner as when it is 1.0 μm. Therefore, any thickness can be selected as long as it is 0.2 μm or more. However, if it becomes too thick, it will not only become the main cause of cost increase, but also become prone to the reduction of luminous efficiency when driven by rated current or the reduction of yield caused by the increase of wafer warping. Therefore, the thickness is preferably set to 10 μm or less.

[0052] In addition, each layer includes the concept of having a plurality of composition layers within the composition range illustrated rather than a single composition layer. In addition, the level of carrier concentration is not uniform in each layer but includes the concept of having a plurality of levels in each layer.

[0053] The active layer 14 may be composed of a single composition. In addition, a superlattice structure composed of multiple alternately stacked barrier layers and active layers 14 has similar functions, and both can be selected. Regardless of which structure is selected, the technical effect of the present invention is the same.

[0054] The thickness of the GaP window layer is preferably greater than 5 μm, and can be 6 μm, for example, but is not limited to 6 μm, and any thickness can be selected as long as it is thinner than the short side length of the device isolation.

[0055] Then, if Figure 2 As shown, benzocyclobutene (BCB), for example, as a thermosetting bonding member 25, is spin-coated on the epitaxial wafer 20, and is overlapped with a transparent substrate 30 such as a sapphire wafer, and is thermocompressed in a vacuum atmosphere. When BCB is applied by spin coating, the film thickness can be set to 0.6 μm, for example. Thus, the epitaxial wafer 20 and the transparent substrate 30 are bonded via the thermosetting bonding member 25, and the thermosetting bonding member 25 is cured to bond them to form a bonded wafer.

[0056] The atmosphere for thermocompression bonding is not limited to a vacuum atmosphere, and any atmosphere can be used as long as the oxygen content is 100 ppm or less. For example, a nitrogen atmosphere or an argon atmosphere can achieve the same effect.

[0057] The transparent substrate 30 is not limited to sapphire, and any material can be selected as long as the LLO laser light transmittance and flatness can be ensured. In addition to sapphire, quartz can also be selected.

[0058] When BCB is used as the thermosetting bonding member 25, the same result can be obtained by applying BCB in a layer or patterning it into an isolated island shape, a line shape, or other shapes using photosensitive BCB and performing the bonding process.

[0059] Furthermore, the thickness of the thermosetting bonding member 25 such as BCB is not limited to 0.6 μm, and may be thinner than this thickness.

[0060] Then, if Figure 3As shown, the starting substrate 11 (for example, a GaAs starting substrate) is removed by wet etching, and then the etching stop layer 12 is also removed. Regarding the removal of the etching stop layer 12, in the case of having the first etching stop layer and the second etching stop layer as described above, first, the first etching stop layer is exposed by etching, and the second etching stop layer is removed by changing the etchant, so that the epitaxial layer (the first cladding layer 13 in the light emitting element structure 18) can be exposed. In this way, a bonding substrate (DH) that only retains the double heterogeneous (DH) structure (the first cladding layer 13, the active layer 14, the second cladding layer 15) and the window layer 16 can be produced. Figure 3 ).

[0061] After preparing the bonding wafer in the above manner, in the present invention, the bonding wafer is introduced into a plasma atmosphere, and the poor bonding portion of the thermosetting bonding member 25 that is not sufficiently cured is selectively destroyed, thereby removing the poor bonding portion. That is, after the thermosetting bonding member 25 is cured, the bonding wafer is introduced into a plasma atmosphere, and the poor bonding portion of the thermosetting bonding member 25 that is not sufficiently cured is selectively destroyed, thereby removing the poor bonding portion. Thus, a bonding wafer in which the poor bonding portion of the thermosetting bonding member 25 that is not sufficiently cured is selectively destroyed can be manufactured. At this time, it is preferred that the plasma atmosphere is set to: in a plasma generating device having a barrel-type or parallel plate-type electrode structure, a plasma atmosphere formed by plasmaizing any one or more gases including oxygen, nitrogen, argon, helium, and hydrogen. In addition, in the present invention, the device that can generate the plasma atmosphere can be set to a RIE (Reactive Ion Etching, reactive ion etching) device, an ICP (Inductively Coupled Plasma, inductively coupled plasma) device, a plasma CVD device, an ashing device, or a sputtering device. In the first embodiment, an example in which the plasma generator is used as an ashing device will be described.

[0062] The decompression degree of the plasma atmosphere can be set to, for example, 100 [Pa], oxygen is introduced at, for example, 100 sccm, and the atmosphere in which the oxygen plasma is generated is maintained for, for example, 5 minutes. The introduced gas, in addition to oxygen, can also be introduced to perform plasma treatment by introducing a gas mixed with any one or more of nitrogen, argon, helium, and hydrogen, and the same effect can be obtained. However, the gas does not include a mixed gas of oxygen and hydrogen.

[0063] The above plasma conditions are only examples and are not limited to the above values. The pressure can be higher or lower than the pressure in the examples, for example, it can be freely set between 5 and 150 Pa. The gas flow rate is also a design factor for the plasma generation density. As long as the pressure control allows, the same effect can be obtained even if the flow rate is more or less than the example.

[0064] When the above plasma treatment is performed, the poorly cured portion of the thermosetting bonding member 25 such as BCB is charged up / heated by the plasma, and the poorly cured portion is expanded and vaporized. As a result, the poorly cured thermosetting bonding member (such as a poor BCB layer portion) and the epitaxial layer on the poorly cured portion are peeled off from the bonding substrate, and the poor portion is removed.

[0065] After the plasma treatment, the wafer can be cleaned as appropriate. For example, the wafer is rotated while being heated at 5 kg / cm 2 The organic solvent is sprayed at a pressure of 10000 to remove the peeled BCB and epitaxial layer attached to the surface, and then the pure water cleaning and spin drying are performed.

[0066] (Second embodiment)

[0067] Next, the second embodiment will be described. The second embodiment is an example in which the plasma generator is a plasma generator having a parallel plate structure. The process and structure of manufacturing the bonded wafer are the same as those of the first embodiment.

[0068] The bonded wafer is introduced into a plasma generator having a parallel plate structure, and plasma treatment is performed in a reduced pressure atmosphere. In this embodiment, the plasma generator is set as an RIE device, an ICP device, or other devices having a parallel plate structure. In addition, in order to form the element shape, dry etching treatment by an ICP device is also performed in the subsequent process, but the plasma treatment of the present invention is performed before the subsequent process as described above.

[0069] The reduced pressure atmosphere can be set to, for example, 1.0 [Pa], and oxygen is introduced at, for example, 50 sccm, so that oxygen plasma is generated and processed, thereby removing the defective part. In addition, in addition to oxygen, when a gas mixed with any one or more of nitrogen, argon, helium, and hydrogen is introduced to perform plasma processing, the same effect can be obtained. However, the aforementioned gases do not include a mixed gas of oxygen and hydrogen.

[0070] In addition to the aforementioned gases, the same effect can be obtained by introducing reactive gases such as chlorine or fluorine. However, when these reactive gases are introduced, etching of the surface of the light emitting structure proceeds even with weak plasma, so it is preferable to use the aforementioned gases.

[0071] The plasma conditions are only examples and are not limited to the above values. The pressure can be higher or lower than the pressure in the examples, for example, it can be freely set between 0.1 and 10 Pa. The gas flow rate is also a design factor for the plasma generation density. As long as the pressure control allows, the same effect can be obtained even if the flow rate is more or less than the example.

[0072] After the plasma treatment, the wafer is rotated at a speed of, for example, 5 kg / cm 2 The organic solvent is sprayed at a pressure of 10000 to remove the peeled BCB and epitaxial layer attached to the surface, and then the pure water cleaning and spin drying are performed.

[0073] (Third Implementation Method)

[0074] Next, the third embodiment will be described. The third embodiment is an example in which the plasma generator is a plasma CVD device. The process and structure of manufacturing the bonded wafer are the same as those of the first embodiment.

[0075] The bonded wafer is introduced into a plasma CVD apparatus, and plasma film formation is performed in a reduced pressure atmosphere to remove defective portions.

[0076] The reduced pressure atmosphere can be set to 5.0 [Pa], for example, and TEOS (tetraethoxysilane) is introduced at, for example, 20 sccm, and oxygen is introduced at, for example, 50 sccm, to form a SiO2 film. In addition, the film formation is not limited to the SiO2 film, and the same effect can be obtained when other silicon-containing films such as SiNx, phosphosilicate glass (PSG), and nitride oxide (SiNxOx) are formed.

[0077] The plasma conditions are only examples and are not limited to the above values. Pressure is a parameter that determines the film formation rate, so the same effect can be obtained even if the pressure is higher or lower than the example. For example, it can be freely set between 0.1 and 10 Pa. The gas flow rate is also a design factor for the plasma generation density, that is, a parameter of the film formation rate. As long as the pressure control allows, the same effect can be obtained even if the flow rate is more or less than the example.

[0078] After the film is formed, the film can be removed by etching. For example, after the SiO2 film is formed, wet etching is performed using a hydrofluoric acid solution to remove the SiO2 film.

[0079] (Fourth Implementation Method)

[0080] Next, the fourth embodiment will be described. The fourth embodiment is an example in which the plasma generator is a sputtering device. The process and structure of manufacturing the bonded wafer are the same as those of the first embodiment.

[0081] The bonded wafer is introduced into a sputtering device, and sputtering film formation is performed in a reduced pressure atmosphere to remove defective portions.

[0082] The reduced pressure atmosphere can be set to, for example, 2.0 [Pa], and RF plasma is fired at a SiO2 target, thereby forming a SiO2 film. In addition, the film formation is not limited to SiO2 films, and the same effect can be obtained when forming other films that can be wet-etched, such as Ti, Al, TiO2, ZnO, NbOx, SiNx, TiNx, etc.

[0083] The plasma conditions are only examples and are not limited to the above values. Pressure is a parameter that determines the film formation rate, so the same effect can be obtained even if the pressure is higher or lower than the example. For example, it can be freely set between 0.1 and 10 Pa. The gas flow rate is also a design factor for the plasma generation density, that is, a parameter of the film formation rate. As long as the pressure control allows, the same effect can be obtained even if the flow rate is more or less than the example.

[0084] After the film is formed, the film can be removed by etching. For example, after the SiO2 film is formed, wet etching is performed using a hydrofluoric acid solution to remove the SiO2 film.

[0085] Example

[0086] Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0087] (Example 1)

[0088] First, if Figure 1 As shown in FIG. 1 , an epitaxial wafer having a light emitting element structure as an epitaxial functional layer is prepared. Specifically, as shown below. First, an n-type GaAs buffer layer is stacked on an n-type GaAs starting substrate 11, and then an n-type GaAs layer with a thickness of 0.1 μm is formed. x In 1-x P (0.4 ≤ x ≤ 0.6) first etching stop layer, and n-type GaAs second etching stop layer with a thickness of 0.1 μm, to form etching stop layer 12. On etching stop layer 12, n-type (Al y Ga 1-y ) x In 1-x P (0.4≤x≤0.6, 0.6≤y≤1.0) first cladding layer 13, undoped (Al y Ga 1-y ) x In 1-x P (0.4≤x≤0.6, 0≤y≤0.5) active layer 14, p-type (Al y Ga1-y ) x In 1-x P (0.4≤x≤0.6, 0.6≤y≤1.0) second cladding layer 15, p-type Ga with a thickness of 0.1 μm x In 1-x P (0.5≤x≤1.0) intermediate layer (not shown), p-type GaP window layer 16 with a thickness of 0.6 μm, and an epitaxial wafer 20 having a light emitting element structure as an epitaxial functional layer are prepared. Figure 1 ).

[0089] Then, if Figure 2 As shown, benzocyclobutene (BCB) as the thermosetting bonding member 25 is spin-coated on the epitaxial wafer 20, and the sapphire substrate as the transparent substrate 30 is faced and overlapped, and thermocompression-bonded in a vacuum atmosphere. When BCB is applied by spin coating, the designed film thickness is set to 0.6 μm.

[0090] Then, if Figure 3 As shown, the GaAs starting substrate 11 is removed by wet etching to expose the n-type first etching stop layer, and then the etchant is changed to remove the second etching stop layer to expose the first cladding layer, thereby removing the etching stop layer 12. In this way, an epitaxial bonding substrate with only the DH layer and the window layer 16 can be manufactured.

[0091] The bonded wafer is introduced into an ashing device having a barrel structure, and 100 sccm of oxygen is introduced into a reduced pressure atmosphere of 100 [Pa], and a plasma treatment is performed for 5 minutes in an atmosphere where oxygen plasma is generated. Thus, a bonded wafer is produced in which the poorly bonded portion of the thermally cured bonding member 25 is selectively destroyed.

[0092] After the plasma atmosphere treatment, the wafer is rotated at a speed of, for example, 5 kg / cm 2 The organic solvent was sprayed at a pressure of 100 to remove the peeled BCB and epitaxial layer attached to the surface, and pure water cleaning and spin drying were performed to remove the poorly bonded parts of the bonded wafer. After that, as a subsequent process, dry etching was performed using an ICP device to form the device shape, and the peeling state of the epitaxial layer during the dry etching process was investigated.

[0093] (Example 2)

[0094] For until Figure 3The bonding process was carried out in the same manner as in Example 1 until the preparation of the bonding wafer. The bonding wafer was introduced into an RIE device having a parallel plate structure, and 50 sccm of oxygen was introduced into a reduced pressure atmosphere of 1.0 [Pa] to perform plasma treatment in an atmosphere where oxygen plasma was generated. Otherwise, the bonding defective portion of the bonding wafer was removed under the same conditions as in Example 1. Furthermore, the peeling condition of the epitaxial layer during the dry etching process was investigated in the same manner as in Example 1.

[0095] (Example 3)

[0096] For until Figure 3 The bonding wafer preparation stage was carried out in the same manner as in Example 1. The bonding wafer was introduced into a plasma CVD device, and 20 sccm of TEOS and 50 sccm of oxygen were introduced in a reduced pressure atmosphere of 5.0 [Pa] to form a SiO2 film. After the film formation, the SiO2 film was removed by wet etching using a hydrofluoric acid solution. Except for this, the poor bonding portion of the bonding wafer was removed using the same conditions as in Example 1. In addition, the peeling condition of the epitaxial layer during the dry etching process was investigated in the same manner as in Example 1.

[0097] (Example 4)

[0098] For until Figure 3 The steps from preparation of the bonding wafer to the step of bonding were carried out in the same manner as in Example 1. The bonding wafer was introduced into a sputtering device, and RF plasma was fired at a SiO2 target in a reduced pressure atmosphere of 2.0 [Pa] to form a SiO2 film. After the film was formed, wet etching was performed using a hydrofluoric acid solution to remove the SiO2 film. Other than that, the bonding defective portion of the bonding wafer was removed using the same conditions as in Example 1. In addition, the peeling condition of the epitaxial layer during the dry etching process was investigated in the same manner as in Example 1.

[0099] (Comparative Example)

[0100] After manufacturing the bonded wafer in the same manner as in Example 1 except that plasma treatment is not performed, in order to form the element shape without performing plasma treatment, dry etching treatment is performed by an ICP device as a subsequent process, and the peeling condition of the epitaxial layer during the dry etching treatment is investigated.

[0101] (Comparison between Example and Comparative Example)

[0102] Figure 4The results obtained by comparing the ratio of the epitaxial layer peeling occurrence area during the ICP treatment of the subsequent process in the embodiment and the comparative example are shown in FIG. The degree of residual oxygen is not constant, so the occurrence rate is not constant, but it can be seen that in the case of the embodiment, plasma treatment is carried out before the ICP treatment of the subsequent process to remove the defective part, so that new epitaxial layer peeling will not occur during the ICP treatment of the subsequent process.

[0103] In addition, the method of using FTIR and other techniques to measure the BCB curing rate to investigate the poorly cured position is feasible in itself. If only the poorly cured part is to be detected, alternative means can be used even if the present technology is not used. However, it is difficult to achieve the removal of the poorly cured part after detection at a low cost. The poorly cured part of BCB is an irregular shape. For example, when it is desired to detect the removal part using a photolithography technique using a photomask, etc., it is necessary to prepare a mask, which requires considerable cost. In addition, compared to the present technology, selecting other removal methods after the part is detected by the measurement technique itself will increase the processing time and cost. In the present invention, the detection and removal of the poor part can be completed in one step, so it is a time-saving and simple method.

[0104] The present invention includes the following aspects.

[0105] [1] A method for removing a poorly bonded portion of a bonded wafer, wherein the bonded wafer has a light emitting element structure, wherein the light emitting element structure has (Al y Ga 1-y ) x In 1-x P (0.4≤x≤0.6, 0≤y≤0.5), and the bonding wafer is bonded by curing the thermosetting bonding member to bond the light emitting element structure to the transparent substrate that transmits light of the emission wavelength, and the removal method is characterized in that,

[0106] By introducing the bonded wafer into a plasma atmosphere, the poorly bonded portion where the thermosetting bonding member is insufficiently cured is selectively destroyed, thereby removing the poorly bonded portion.

[0107] [2] The method for removing a poorly bonded portion of a bonded wafer according to [1] above, wherein the thermosetting bonding member is benzocyclobutene.

[0108] [3] The method for removing a poorly bonded portion of a bonded wafer according to [1] or [2] above, wherein the transparent substrate is sapphire or quartz.

[0109] [4] A method for removing a poorly bonded portion of a bonded wafer according to [1], [2] or [3] above, wherein the plasma atmosphere is set to: a plasma atmosphere formed by plasmatizing a gas containing any one or more of oxygen, nitrogen, argon, helium and hydrogen in a plasma generating device having a barrel-type or parallel plate-type electrode structure.

[0110] [5] A method for removing poorly bonded portions of a bonded wafer according to [1], [2], [3] or [4] above, wherein the device for generating a plasma atmosphere is set to a RIE (Reactive Ion Etching) device, an ICP (Inductively Coupled Plasma) device, a plasma CVD device, an ashing device or a sputtering device.

[0111] [6] A method for manufacturing a bonded wafer, comprising the following steps:

[0112] The step of preparing an epitaxial wafer and a transparent substrate, wherein the epitaxial wafer has a light emitting element structure, and the light emitting element structure has (Al y Ga 1-y ) x In 1-x An active layer composed of P (0.4≤x≤0.6, 0≤y≤0.5), the transparent substrate transmits light of the emission wavelength in the light-emitting element structure; and

[0113] The epitaxial wafer and the transparent substrate are bonded together via a thermosetting bonding member and the thermosetting bonding member is cured to form a bonded wafer.

[0114] The manufacturing method is characterized by further comprising: after curing the thermosetting bonding member, introducing the bonding wafer into a plasma atmosphere to selectively destroy a poor bonding portion where the thermosetting bonding member is insufficiently cured, thereby removing the poor bonding portion.

[0115] [7] The method for manufacturing a bonded wafer according to [6] above, wherein the thermosetting bonding member is benzocyclobutene.

[0116] [8] The method for manufacturing a bonded wafer according to [6] or [7] above, wherein the transparent substrate is sapphire or quartz.

[0117] [9] A method for manufacturing a bonded wafer according to [6], [7] or [8] above, wherein the plasma atmosphere is set to be: a plasma atmosphere formed by plasmatizing one or more gases selected from oxygen, nitrogen, argon, helium and hydrogen in a plasma generating device having a barrel-type or parallel plate-type electrode structure.

[0118]

[10] A method for manufacturing a bonded wafer according to [6], [7], [8] or [9] above, wherein the device for generating a plasma atmosphere is set to a RIE (Reactive Ion Etching) device, an ICP (Inductively Coupled Plasma) device, a plasma CVD device, an ashing device or a sputtering device.

[0119] In addition, the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and technical solutions having substantially the same structure and exerting the same technical effects as the technical concept described in the claims of the present invention are all included in the protection scope of the present invention.

Claims

1. A method for removing a poorly bonded portion of a bonded wafer, the method being a method for removing a poorly bonded portion of a bonded wafer, wherein the bonded wafer has a light emitting element structure, wherein the light emitting element structure has a light emitting element structure having a light emitting element structure (Al y Ga 1-y ) x In 1-x The active layer is composed of P, wherein 0.4≤x≤0.6, 0≤y≤0.5, and the bonding wafer is bonded by curing the thermosetting bonding member so that the light emitting element structure is bonded to the transparent substrate that transmits light of the emission wavelength, and the removal method is characterized in that, By introducing the bonded wafer into a plasma atmosphere, the poorly bonded portion where the thermosetting bonding member is insufficiently cured is selectively destroyed, thereby removing the poorly bonded portion.

2. The method for removing a poorly bonded portion of a bonded wafer according to claim 1, wherein: The thermosetting bonding member is made of benzocyclobutene.

3. The method for removing a poorly bonded portion of a bonded wafer according to claim 1 or 2, wherein: The transparent substrate is made of sapphire or quartz.

4. The method for removing a poorly bonded portion of a bonded wafer according to claim 1 or 2, wherein: The plasma atmosphere is a plasma atmosphere formed by converting a gas containing any one or more of oxygen, nitrogen, argon, helium, and hydrogen into plasma in a plasma generator having a barrel-type or parallel-plate-type electrode structure.

5. The method for removing a poorly bonded portion of a bonded wafer according to claim 1 or 2, wherein: The apparatus for generating a plasma atmosphere is set to be an RIE (Reactive Ion Etching) apparatus, an ICP (Inductively Coupled Plasma) apparatus, a plasma CVD apparatus, an ashing apparatus, or a sputtering apparatus.

6. A method for manufacturing a bonded wafer, comprising the following steps: The step of preparing an epitaxial wafer and a transparent substrate, wherein the epitaxial wafer has a light emitting element structure, and the light emitting element structure has (Al y Ga 1-y ) x In 1-x The active layer is composed of P, wherein 0.4≤x≤0.6, 0≤y≤0.5, the transparent substrate transmits light of the emission wavelength in the light emitting element structure; and The epitaxial wafer and the transparent substrate are bonded together via a thermosetting bonding member and the thermosetting bonding member is cured to form a bonded wafer. The manufacturing method is characterized by further comprising: after curing the thermosetting bonding member, introducing the bonding wafer into a plasma atmosphere to selectively destroy a poor bonding portion where the thermosetting bonding member is insufficiently cured, thereby removing the poor bonding portion.

7. The method for manufacturing a bonded wafer according to claim 6, wherein: The thermosetting bonding member is made of benzocyclobutene.

8. The method for manufacturing a bonded wafer according to claim 6 or 7, characterized in that: The transparent substrate is made of sapphire or quartz.

9. The method for manufacturing a bonded wafer according to claim 6 or 7, characterized in that: The plasma atmosphere is a plasma atmosphere formed by converting a gas containing any one or more of oxygen, nitrogen, argon, helium, and hydrogen into plasma in a plasma generator having a barrel-type or parallel-plate-type electrode structure.

10. The method for manufacturing a bonded wafer according to claim 6 or 7, characterized in that: The apparatus for generating the plasma atmosphere is set to be an RIE (Reactive Ion Etching) apparatus, an ICP (Inductively Coupled Plasma) apparatus, a plasma CVD apparatus, an ashing apparatus, or a sputtering apparatus.

Images