A method for integrating an InP HEMT active layer with a quartz substrate

Abstract

The application discloses a quartz substrate InP HEMT active layer integration method, and particularly relates to the following steps: 1: after spin coating a first temporary bonding adhesive on an active layer of a wafer, the wafer is placed on a hot plate for pre-baking; 2: bonding a first support wafer with the active layer; 3: thinning a substrate of the wafer; 4: after spin coating a second temporary bonding adhesive on a second support wafer, the second support wafer is placed on a hot plate for pre-baking; 5: bonding the second support wafer with the wafer substrate; 6: separating the first support wafer from the active layer of the wafer, and cleaning the surface of the active layer of the wafer; 7: spin coating a permanent bonding material on the active layer of the wafer, and permanently bonding the quartz substrate with the active layer of the wafer; 8: separating the second support wafer from the substrate of the wafer, and cleaning the substrate of the wafer; 9: completely removing the substrate of the wafer; and 10: removing a self-stopping layer and a buffer layer of the wafer. The application solves the problem of wafer breakage caused by high-temperature conditions, material thermal mismatch and other factors in the direct bonding process.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor process technology. Background Technology

[0002] Terahertz waves, with their excellent atmospheric penetration and outstanding resolution, have broad application prospects in terahertz imaging, deep space exploration, and terahertz communication. InP HEMTs possess extremely high electron mobility, high saturation drift velocity, and excellent noise performance, making them the preferred material for developing highly integrated, small-volume, and highly reliable terahertz solid-state devices, especially suitable for fabricating high-frequency, high-gain, low-noise, and low-power terahertz amplifiers. However, due to the high dielectric constant of InP (10.8), device losses are relatively high, thus requiring transmission and matching structures such as microstrip lines to be fabricated on quartz substrates. Integrating InP HEMT materials onto quartz substrates using heterogeneous integration technology and directly fabricating InP HEMT devices and interconnect transmission structures on the quartz substrate helps to further improve integration density and reduce transmission losses.

[0003] However, during the integration process, due to the thermal expansion coefficient of quartz material (0.5×10⁻⁶), -6 ℃) and the coefficient of thermal expansion of InP material (4.5×10 ℃) -6 The large temperature difference between the two materials (°C and ℃) leads to a huge thermal mismatch at the integration interface. In addition, InP material is brittle. Therefore, if the quartz substrate and the InP HEMT wafer are directly bonded at high temperature, the stress generated by the huge thermal mismatch can easily cause the thick InP substrate to crack. Summary of the Invention

[0004] Purpose of the invention: In order to solve the problems existing in the prior art, the present invention provides a method for integrating InPHEMT active layers on a quartz substrate.

[0005] Technical solution: This invention provides a method for integrating the active layer of an InP HEMT on a quartz substrate, specifically including the following steps:

[0006] Step 1: Spin-coat the first temporary bonding adhesive onto the active layer of the InP HEMT wafer; and place the InP HEMT wafer coated with the first temporary bonding adhesive on a hot plate for pre-baking.

[0007] Step 2: Bond the first support substrate to the active layer of the InP HEMT wafer using a first temporary bonding adhesive;

[0008] Step 3: Thin the substrate of the InP HEMT wafer;

[0009] Step 4: Spin-coat the second temporary bonding adhesive onto the second support substrate, and then place the second support substrate on a hot plate for pre-baking;

[0010] Step 5: Bond the second support substrate to the thinned InP HEMT wafer substrate using the second temporary bonding adhesive;

[0011] Step 6: Separate the first support substrate from the active layer of the InP HEMT wafer and clean the surface of the active layer of the InP HEMT wafer.

[0012] Step 7: Spin-coat permanent bonding material onto the active layer of the InP HEMT wafer, and permanently bond the quartz substrate to the active layer of the InP HEMT wafer;

[0013] Step 8: Separate the second support carrier from the substrate of the InP HEMT wafer and clean the InP HEMT wafer substrate;

[0014] Step 9: Completely remove the substrate from the InP HEMT wafer;

[0015] Step 10: Remove the self-stopping layer and buffer layer from the InP HEMT wafer.

[0016] Furthermore, the first and second temporary bonding adhesives are photoresist, HT10.10, Su 8, Prolift 100 or PI; the spin speed for spin coating the first or second temporary bonding adhesive is 1000-5000 rpm, and the spin coating time is 30s-2 minutes.

[0017] Furthermore, in step 1, the hot plate temperature is set to 110℃-200℃ and the baking time is set to 2-4 minutes; in step 4, when the second support carrier is placed on the hot plate for pre-baking, the hot plate temperature is set to 110℃-160℃ and the baking time is 2-4 minutes.

[0018] Furthermore, the first and second support substrates are made of the same material, namely sapphire, InP, SiC, or quartz wafers; the thickness of the first support substrate is 500μm-1000μm.

[0019] Furthermore, in step 2, the bonding temperature is set to 190℃-250℃ and the bonding time is set to 10 minutes-30 minutes; in step 5, when the second support carrier is bonded to the InP HEMT wafer substrate, the bonding temperature is set to 160℃-200℃ and the bonding time is 10-20 minutes.

[0020] Furthermore, in step 3, the substrate of the InP HEMT wafer is thinned by any one or a combination of mechanical grinding, mechanical polishing, and chemical polishing. The remaining thickness of the InP HEMT wafer substrate after thinning is 10μm-200μm.

[0021] Furthermore, in step 6, when separating the first support carrier from the active layer of the InP HEMT wafer, or in step 8, when separating the second support carrier from the substrate of the InP HEMT wafer, the separation method is pyrolysis, gas debonding, or laser debonding; when cleaning the active layer of the InP HEMT wafer or the substrate of the InP HEMT wafer, adhesive remover, acetone, or alcohol is used.

[0022] Furthermore, the softening temperature of the second temporary bonding adhesive is lower than the failure temperature of the first temporary bonding adhesive; the separation temperature between the first and second temporary bonding adhesives is lower than the highest temperature that the InP HEMT active layer material can withstand.

[0023] Furthermore, the permanent bonding material in step 7 is benzocyclobutene, polyimide polymer, silicon dioxide, or aluminum oxide; the thickness of the permanent bonding material is 50 nm-10 μm.

[0024] Furthermore, in step 7, the permanent bonding method is either thermo-press bonding or activation bonding. The temperature during permanent bonding is 100-300℃, the permanent bonding time is 1 minute-10 hours, and the bonding pressure during permanent bonding is 200-60000N.

[0025] Beneficial effects: This invention solves the problem of bonded wafer breakage caused by high temperature conditions and material thermal mismatch during conventional direct bonding; this invention provides material support for the fabrication of high-performance, high-reliability quartz-based InP HEMT terahertz devices. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure after spin-coating the first temporary bonding adhesive onto the active layer of an InP HEMT wafer.

[0027] Figure 2 This is a schematic diagram of the structure after the active layer of the InP HEMT wafer is temporarily bonded to the first support substrate.

[0028] Figure 3 This is a schematic diagram of the structure of an InP HEMT wafer after the substrate has been thinned.

[0029] Figure 4 This is a schematic diagram of the structure after the substrate of the thinned InP HEMT wafer is temporarily bonded to the second support carrier;

[0030] Figure 5 This is a schematic diagram of the structure after the active layer of the InP HEMT wafer has been separated from the first support substrate and cleaned.

[0031] Figure 6 This is a schematic diagram of the structure after spin-coating permanent bonding material onto the active layer of an InP HEMT wafer;

[0032] Figure 7 This is a schematic diagram of the structure after the active layer of an InP HEMT wafer is permanently bonded to a quartz substrate.

[0033] Figure 8 This is a schematic diagram of the structure after the second support carrier is separated and the InP HEMT wafer substrate is cleaned;

[0034] Figure 9 This is a schematic diagram of the structure of an InP HEMT wafer after the remaining substrate has been completely removed.

[0035] Figure 10 This is a schematic diagram of the structure of an InP HEMT wafer after the self-stopping layer and buffer layer have been completely removed.

[0036] Explanation of reference numerals in the attached figures: 1. Active layer of InP HEMT wafer; 2. Self-stopping layer and buffer layer of InP HEMT wafer; 3. Substrate of InP HEMT wafer; 4. First temporary bonding adhesive; 5. First support carrier; 6. Second temporary bonding adhesive; 7. Second support carrier; 8. Permanent bonding material; 9. Quartz substrate. Detailed Implementation

[0037] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0038] This embodiment provides a method for integrating the active layer of an InP HEMT on a quartz substrate, including the following steps:

[0039] Step 1: As Figure 1 As shown, a first temporary bonding adhesive is spin-coated onto the active layer of the InP HEMT wafer: A first temporary bonding adhesive 4 is spin-coated onto the source layer 1 of the InP HEMT wafer, wherein the InP HEMT consists of an InP substrate 3, a self-stopping layer and a buffer layer 2, and an inverted epitaxially grown HEMT active layer 1; the first temporary bonding adhesive is a photoresist, HT10.10, Su 8, Prolift 100, or PI. The spin-coating speed is set to 1000-5000 rpm and the spin-coating time is 30s-2 minutes according to the required thickness. The wafer coated with the first temporary bonding adhesive is placed face up on a hot plate for pre-baking. The hot plate temperature is set to 110℃-200℃ and the time is 2-4 minutes.

[0040] Step 2: As Figure 2As shown, the InP HEMT wafer is temporarily bonded to the first support substrate 5: the InP HEMT wafer coated with the first temporary bonding adhesive is temporarily bonded to the first support substrate. In this embodiment, the first support substrate is selected from sapphire, InP, SiC or quartz wafers. The thickness of the first support substrate is 500μm-1000μm, the temporary bonding temperature is set to 190℃-250℃, and the bonding time is 10 minutes-30 minutes.

[0041] Step 3: As Figure 3 As shown, the substrate of the InP HEMT wafer temporarily bonded to the first support substrate is thinned: the InP substrate of the InP HEMT wafer temporarily bonded to the first support substrate is thinned by mechanical grinding, mechanical polishing, or chemical polishing to reduce the thickness of the InP substrate to 10μm-200μm (this thickness facilitates the subsequent removal of the remaining substrate by etching; if the remaining substrate is too thick, the self-stopping layer etching selectivity will be insufficient, leading to over-etching and damage to the active layer; if the remaining substrate is too thin, the stress during the thinning process will be large, introducing residual stress into the active layer, which will also affect the device quality).

[0042] Step 4: Spin-coating the second temporary bonding adhesive onto the second support substrate 7: Spin-coating the second temporary bonding adhesive 6 onto the second support substrate 7. The second support substrate is one of sapphire, InP, SiC, or quartz wafers. To reduce thermal mismatch, the material of the second support substrate is the same as that of the first support substrate. The second temporary bonding adhesive is photoresist, HT10.10, Su 8, Prolift 100, or PI. The spin-coating speed is set to 1000-5000 rpm, and the spin-coating time is 30 seconds to 2 minutes, depending on the required thickness. The second temporary substrate coated with the second temporary bonding adhesive is then placed on a hot plate for pre-baking. The hot plate temperature is set to 110℃-160℃, and the time is 2-4 minutes. The softening temperature of the second temporary bonding adhesive is lower than the failure temperature of the first temporary bonding adhesive, and the separation temperature between the first and second temporary bonding adhesives is lower than the maximum temperature that the InP HEMT active layer material and device can withstand.

[0043] Step 5: As Figure 4 As shown, the substrate of the thinned InP HEMT wafer is temporarily bonded to the second support substrate: the substrate of the thinned InP HEMT wafer is temporarily bonded to the second support substrate, the temporary bonding temperature is set to 160℃-200℃, and the bonding time is 10 minutes-20 minutes (this bonding time has a better temporary bonding effect, resulting in fewer voids at the temporary bonding interface).

[0044] Step 6: As Figure 5As shown, the first support substrate is separated from the active layer of the InP HEMT wafer, and the active layer of the InP HEMT wafer is then cleaned. The separation method can be pyrolysis, gas debonding, or laser debonding, etc. The separation of the first support substrate will not damage the structure formed by the InP HEMT wafer (after substrate thinning) and the second support substrate. In this embodiment, laser debonding is used to separate the first support substrate. Then, the surface of the active layer of the InP HEMT wafer is cleaned with chemical reagents such as resist remover, acetone, and alcohol.

[0045] Step 7: As Figure 6 As shown, a permanent bonding material is spin-coated onto the active layer of the InP HEMT wafer: The permanent bonding material can be a dielectric material such as BCB (benzocyclobutene), PI (polyimide) polymer, silicon oxide, or aluminum oxide; the thickness of the permanent bonding material can be 50 nm to 10 μm as needed.

[0046] Step 8: As Figure 7 As shown, the active layer of the InP HEMT wafer is permanently bonded to the quartz substrate: the active layer of the InP HEMT wafer and the quartz substrate are placed face to face in a bonding machine for permanent bonding. The permanent bonding method can be hot-press bonding or activated bonding, depending on the permanent bonding material used. The bonding temperature is 100℃ to 300℃, the bonding time is 1 minute to 10 hours, and the bonding pressure is 200N to 60000N. At the permanent bonding temperature, the second temporary bonding adhesive will not fail.

[0047] Step 9: As Figure 8 As shown, the second support carrier is separated from the substrate of the InP HEMT wafer, and the back side of the InP HEMT wafer substrate is cleaned: the second support carrier is separated from the substrate of the InP HEMT wafer by means of pyrolysis, gas debonding or laser debonding, and the back side of the InP HEMT is cleaned with chemical reagents such as adhesive remover, acetone, and alcohol.

[0048] Step 10: As Figure 9 As shown, the remaining substrate of the InP HEMT wafer is thinned and completely removed: the remaining InP substrate of the InP HEMT wafer is completely removed using an etching solution, exposing a self-stopping layer and a buffer layer that have a high selectivity to the etching solution.

[0049] Step 11: As Figure 10As shown, the self-stop layer and buffer layer of the InP HEMT wafer are removed by using an etch solution or dry etching method to remove the self-stop layer and buffer layer, exposing the surface of the InP HEMT active layer, and obtaining the InP HEMT transferred to the quartz substrate. This removal method has a high selectivity for the self-stop layer and the InP HEMT active layer and will not damage the active layer.

[0050] An embodiment of the present invention:

[0051] Step A: Spin-coat Brewer C1301 temporary bonding agent onto the front side (i.e., the buffer layer) of the InP HEMT wafer, which consists of an InP substrate, a buffer layer, and an inverted epitaxially grown HEMT active layer. The spin-coating thickness is approximately 15 μm, the spin-coating speed is 1500 rpm, the spin-coating time is 60 s, and the pre-baking temperature is 120℃ for 5 minutes. Then, spin-coat a temporary bonding release layer T1107 onto the first support substrate made of SiC. The spin-coating thickness is approximately 10 μm, the spin-coating speed is 2500 rpm, the spin-coating time is 60 s, and the pre-baking temperature is 300℃ for 5 minutes.

[0052] Step B: Temporarily bond the InP HEMT wafer with the first temporary bonding adhesive Brewer C1301 on the front side to the first SiC support substrate with the front side facing each other. The temporary bonding temperature is set to 180℃ and the bonding time is 10 minutes.

[0053] Step C: The InP substrate of the InP HEMT wafer, which is temporarily bonded to the first SiC support substrate, is thinned to 100 μm by mechanical grinding.

[0054] Step D: Spin-coat the front side of the SiC second support carrier and the back side of the thinned InP HEMT substrate with the second temporary bonding adhesive Brewer HT10.10. The spin-coating speed is set to 2000 rpm, the spin-coating time is 1 minute, and the hot plate temperature is set to 160℃.

[0055] Step E: Temporarily bond the back side of the thinned InP HEMT wafer (i.e., the InP substrate) to the front side of the second support wafer. The temporary bonding temperature is set to 190°C and the bonding time is 10 minutes.

[0056] Step F: The SiC first support substrate is separated from the structure formed by the thinned InP HEMT wafer and the SiC second support substrate by laser debonding, and then the adhesive on the InP HEMT surface is cleaned with chemical reagents.

[0057] Step G: Spin-coat a 2μm thick layer of BCB on the front side of the InP HEMT wafer as a permanent bonding material.

[0058] Step H: Place the front side of the InP HEMT wafer face-to-face with the front side of the quartz substrate in a bonding machine for permanent bonding. The bonding temperature is 180℃, the bonding time is 1 hour, and the bonding pressure is 500N.

[0059] Step 1: Place the structure consisting of the SiC second support carrier, the InP HEMT wafer, and the quartz substrate onto a wafer pusher, heat it to 200°C for separation, and then clean the back side of the InP HEMT with chemical reagents.

[0060] Step J: Use an etching solution of HCl:H3PO4=1:1 to remove all remaining InP substrate from the InP HEMT wafer permanently bonded to the quartz substrate, exposing a buffer layer and an InGaAs self-stopping layer that have a high selectivity to the etching solution.

[0061] Step K: Use an H2SO4:H2O2:H2O=1:1:5 etching solution or dry etching method to completely remove the buffer layer and InGaAs from the stop layer, exposing the surface of the InP HEMT active layer.

[0062] Through the above steps, a method for integrating InP HEMT active layers on a quartz substrate was realized.

[0063] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A method for integrating active layers in InP HEMT on a quartz substrate, characterized in that, Specifically, the steps include the following: Step 1: Spin-coat the first temporary bonding adhesive onto the active layer of the InP HEMT wafer; and place the InP HEMT wafer coated with the first temporary bonding adhesive on a hot plate for pre-baking. Step 2: Bond the first support substrate to the active layer of the InP HEMT wafer using a first temporary bonding adhesive; Step 3: Thin the substrate of the InP HEMT wafer; Step 4: Spin-coat the second temporary bonding adhesive onto the second support substrate, and then place the second support substrate on a hot plate for pre-baking; Step 5: Bond the second support substrate to the thinned InP HEMT wafer substrate using the second temporary bonding adhesive; Step 6: Separate the first support substrate from the active layer of the InP HEMT wafer and clean the surface of the active layer of the InP HEMT wafer. Step 7: Spin-coat permanent bonding material onto the active layer of the InP HEMT wafer, and permanently bond the quartz substrate to the active layer of the InP HEMT wafer; Step 8: Separate the second support carrier from the substrate of the InP HEMT wafer and clean the InP HEMT wafer substrate; Step 9: Completely remove the substrate from the InP HEMT wafer; Step 10: Remove the self-stopping layer and buffer layer from the InP HEMT wafer.

2. The method for integrating an active layer of an InP HEMT on a quartz substrate according to claim 1, characterized in that, The first and second temporary bonding adhesives are photoresist, HT10.10, Su 8, Prolift 100 or PI; the spin speed for spin coating the first or second temporary bonding adhesive is 1000-5000 rpm and the spin coating time is 30s-2 minutes.

3. The method for integrating an active layer of an InP HEMT on a quartz substrate according to claim 1, characterized in that, In step 1, the hot plate temperature is set to 110℃-200℃ and the baking time is set to 2-4 minutes; in step 4, when the second support carrier is placed on the hot plate for pre-baking, the hot plate temperature is set to 110℃-160℃ and the baking time is set to 2-4 minutes.

4. The method for integrating an active layer of an InP HEMT on a quartz substrate according to claim 1, characterized in that, The first and second support substrates are made of the same material, namely sapphire, InP, SiC or quartz wafers; the thickness of the first support substrate is 500μm-1000μm.

5. The method for integrating an active layer of an InP HEMT on a quartz substrate according to claim 1, characterized in that, In step 2, the bonding temperature is set to 190℃-250℃ and the bonding time is set to 10 minutes-30 minutes; in step 5, when the second support carrier is bonded to the InP HEMT wafer substrate, the bonding temperature is set to 160℃-200℃ and the bonding time is set to 10-20 minutes.

6. The method for integrating an active layer of an InP HEMT on a quartz substrate according to claim 1, characterized in that, In step 3, the substrate of the InP HEMT wafer is thinned by any one or a combination of mechanical grinding, mechanical polishing, and chemical polishing. The remaining thickness of the InP HEMT wafer substrate after thinning is 10μm-200μm.

7. The method for integrating an active layer of an InP HEMT on a quartz substrate according to claim 1, characterized in that, When separating the first support carrier from the active layer of the InP HEMT wafer in step 6 or separating the second support carrier from the substrate of the InP HEMT wafer in step 8, the separation method is pyrolysis, gas debonding or laser debonding; when cleaning the active layer of the InP HEMT wafer or the substrate of the InP HEMT wafer, adhesive remover, acetone or alcohol is used.

8. The method for integrating an active layer of an InP HEMT on a quartz substrate according to claim 1, characterized in that, The softening temperature of the second temporary bonding adhesive is lower than the failure temperature of the first temporary bonding adhesive; the separation temperature of the first and second temporary bonding adhesives is lower than the highest temperature that the InP HEMT active layer material can withstand.

9. The method for integrating an active layer of an InP HEMT on a quartz substrate according to claim 1, characterized in that, The permanent bonding material in step 7 is benzocyclobutene, polyimide polymer, silicon dioxide, or aluminum oxide; the thickness of the permanent bonding material is 50 nm-10 μm.

10. The method for integrating an active layer of an InP HEMT on a quartz substrate according to claim 1, characterized in that, In step 7, the permanent bonding method is either hot-press bonding or activation bonding. The temperature for permanent bonding is 100-300℃, the permanent bonding time is 1 minute to 10 hours, and the bonding pressure is 200-60000N.

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