A silicon carbide wafer processing process

Abstract

The application discloses a silicon carbide wafer processing technology, which comprises the following steps: S1, permanently bonding a silicon carbide substrate on a silicon carrier plate; S2, completing thinning of the silicon carbide substrate and other front surface processes of the wafer except high-temperature processes; S3, transferring the silicon carbide substrate to a graphite tray, releasing the permanent bonding between the silicon carbide substrate and the silicon carrier plate, and removing the silicon carrier plate; S4, carrying out high-temperature processes on the silicon carbide substrate by using the graphite tray; S5, bonding a glass carrier plate to the back surface of the silicon carbide substrate and removing the graphite tray; S6, bonding a glass carrier plate to the front surface of the silicon carbide substrate and removing the glass carrier plate on the back surface by debonding; S7, completing wafer processes on the back surface of the silicon carbide substrate; and S8, transferring the silicon carbide substrate to a cutting mold, removing the glass carrier plate on the front surface by debonding, and completing wafer cutting. The silicon carbide substrate is thinned by using the silicon carrier plate, and the silicon carbide substrate is carried out high-temperature processes by using the graphite tray, so that the processing difficulty of the silicon carbide material with high hardness and high activation temperature is overcome.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor processing, in particular to a silicon carbide wafer processing technology. BACKGROUND

[0002] As a new generation of wide band gap semiconductor material, silicon carbide has extremely excellent performance in the field of power semiconductor, and is also the frontier and future direction of the development of power semiconductor devices. Silicon carbide is a compound semiconductor material composed of silicon and carbon. Silicon carbide material has excellent characteristics such as large band gap, high breakdown field strength, large thermal conductivity, large saturation velocity, and high maximum working temperature. These excellent characteristics also enable silicon carbide electronic devices to work in high-voltage, high-heat, and high-frequency environments, so silicon carbide is considered to be the best material for making high-power electronic devices compared with gallium arsenide and silicon.

[0003] At present, there are many difficulties in the production and manufacturing process of silicon carbide semiconductor. First, the temperature required for high-temperature processing of silicon carbide material is high, and conventional glass carrier plate technology cannot meet the requirements. High-temperature processing will cause the adhesive to decompose, resulting in the glass carrier plate falling off and being unable to effectively support the silicon carbide wafer, so a new carrier plate technology must be developed to adapt to the processing of silicon carbide wafers. Secondly, the back thinning and gold plating process will be carried out in the later stage of the manufacturing process of silicon carbide power semiconductor products. However, the thinning process on the existing silicon device production line is only suitable for the thinning of silicon wafers. Since silicon carbide has high hardness, the carrier plate cannot withstand the pressure and torque during grinding and thinning, and there is also a risk of cracking. SUMMARY

[0004] To solve the problems mentioned in the background, the purpose of the present application is to provide a silicon carbide wafer processing technology. SiO2 layer is deposited on the back of the silicon carbide substrate by CVD, and then the silicon carbide substrate is bonded to the silicon carrier plate. The silicon carbide substrate and the silicon carrier plate are permanently bonded by SiO2. Then the substrate is thinned, and the hardness of the silicon carrier plate can withstand the large pressure and torque during thinning. At the same time, a graphite tray is used to carry the silicon carbide substrate for high-temperature processing, which overcomes the limitation of temperature on the carrier plate during high-temperature processing of the silicon carbide substrate, and can safely and effectively perform high-temperature tempering of the silicon carbide substrate.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] A silicon carbide wafer processing technology, comprising the following steps:

[0007] S1, depositing a SiO2 layer on the back of the silicon carbide substrate by CVD, and then bonding the back of the silicon carbide substrate to the silicon carrier plate, forming a permanent bond between the silicon carbide substrate and the silicon carrier plate by SiO2;

[0008] S2, thinning the silicon carbide substrate and completing other wafer front processing except high-temperature processing.

[0009] S3, transferring the silicon carbide substrate completing the front wafer process to a graphite tray, then placing the graphite tray into an etching tank to etch the SiO2 layer, releasing the permanent bonding between the silicon carbide substrate and the silicon carrier plate, and removing the silicon carrier plate, then rinsing the silicon carbide substrate clean;

[0010] S4, using the graphite tray to carry the silicon carbide substrate to perform high-temperature process;

[0011] S5, taking out the silicon carbide substrate completing the high-temperature process, coating the back of the silicon carbide substrate with adhesive and bonding a glass carrier plate, and removing the graphite tray;

[0012] S6, coating the front and back of the silicon carbide substrate with adhesive and bonding a glass carrier plate, using laser to penetrate the back of the silicon carbide substrate and the glass carrier plate to decompose the release agent, releasing the bonding between the back of the silicon carbide substrate and the glass carrier plate, and removing the glass carrier plate from the back of the silicon carbide substrate;

[0013] S7, completing the wafer process on the back of the silicon carbide substrate;

[0014] S8, transferring the silicon carbide substrate to a cutting mold, using laser to penetrate the front of the silicon carbide substrate and the glass carrier plate to decompose the release agent, releasing the bonding between the front of the silicon carbide substrate and the glass carrier plate, removing the glass carrier plate from the front of the silicon carbide substrate, and completing the cutting of the wafer.

[0015] Further preferably, in step S1, a plurality of silicon carbide substrates are bonded with the silicon carrier plate at one time, and the specific steps are as follows:

[0016] S101, cleaning the silicon carrier plate and the silicon carbide substrate, and treating the surface of the silicon carrier plate by plasma to excite the active bonds of the silicon carrier plate;

[0017] S102, horizontally arranging and bonding the silicon carbide substrate on the surface of the silicon carrier plate;

[0018] S103, placing the silicon carrier plate with the silicon carbide substrate into a high-temperature furnace tube to perform high-temperature tempering, so that the silicon carbide substrate and the silicon carrier plate form a permanent bonding structure.

[0019] Further preferably, in step S103, the temperature of the high-temperature tempering is 800-1400℃, and the temperature rising rate of the high-temperature furnace tube is less than 15℃ / min.

[0020] Further preferably, in step S3, grooves are formed on the surface of the graphite tray corresponding to the silicon carbide substrate, and the size of the grooves is matched with the size of the silicon carbide substrate.

[0021] Further preferably, in step S3, the etching selectivity of SiO2 and Si is different by using etching liquid, and the SiO2 layer is removed by etching.

[0022] The present application has the following advantages:

[0023] The present application forms a permanent bond between the SiO2 layer deposited on the silicon carrier plate and the silicon carbide substrate, and then thins the silicon carbide substrate, the hardness of the silicon carrier plate can withstand the large pressure and turning force during thinning, and the graphite tray is used to support the silicon carbide substrate for high-temperature processing, which overcomes the limitation of temperature on the carrier plate in the high-temperature processing of the silicon carbide substrate, and can safely and effectively perform high-temperature tempering of the silicon carbide substrate. BRIEF DESCRIPTION OF DRAWINGS

[0024] The present application will be further described below with reference to the accompanying drawings.

[0025] Figure 1 is a process forming schematic diagram of step S1 of the present application;

[0026] Figure 2 is a process forming schematic diagram of step S3 of the present application;

[0027] Figure 3 is a process forming schematic diagram of step S5 of the present application;

[0028] Figure 4 is a process forming schematic diagram of step S6 of the present application;

[0029] Figure 5 is a process forming schematic diagram of step S8 of the present application. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0031] In the description of the present application, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inner", "periphery" and the like indicate the orientation or positional relationship, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the components or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0032] As shown in Figures 1-5 A silicon carbide wafer processing process, comprising the following steps:

[0033] S1, depositing a SiO2 layer on the back surface of the silicon carbide substrate by CVD, cleaning the silicon carrier and the silicon carbide substrate, treating the surface of the silicon carrier by plasma after cleaning, bonding a plurality of small-size silicon carbide substrates to the large-size silicon carrier according to a certain pattern, and finally placing them into a high-temperature furnace tube at 800-1200°C for high-temperature tempering, with a heating rate of 12°C / min, so that the silicon carbide substrate and the silicon carrier form a permanent bonding structure;

[0034] S2, thinning the silicon carbide substrate, and completing other wafer front surface processes except high-temperature processes;

[0035] S3, transferring the silicon carbide substrate after the front surface wafer process to a graphite tray, the graphite tray having a groove corresponding to the silicon carbide substrate to prevent the silicon carbide substrate from falling off after debonding, then placing the graphite tray into an etching tank to etch the SiO2 and Si using an etching liquid with different etching selectivity to remove the SiO2 layer, debonding the silicon carbide substrate and the silicon carrier, and removing the silicon carrier after rinsing the silicon carbide substrate clean;

[0036] S4, using the graphite tray to carry the silicon carbide substrate for high-temperature processes;

[0037] S5, taking out the silicon carbide substrate after the high-temperature process, coating the back surface of the silicon carbide substrate with an adhesive and bonding a glass carrier, and removing the graphite tray;

[0038] S6, coating the front and back surfaces of the silicon carbide substrate with an adhesive and bonding a glass carrier, decomposing the release agent by laser penetrating the back surface of the silicon carbide substrate and the glass carrier, debonding the back surface of the silicon carbide substrate and the glass carrier, and removing the glass carrier on the back surface of the silicon carbide substrate;

[0039] S7, completing the wafer process on the back surface of the silicon carbide substrate;

[0040] S8, transferring the silicon carbide substrate to a cutting mold, decomposing the release agent by laser penetrating the front surface of the silicon carbide substrate and the glass carrier, debonding the front surface of the silicon carbide substrate and the glass carrier, removing the glass carrier on the front surface of the silicon carbide substrate, and completing the wafer cutting.

[0041] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0042] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A silicon carbide wafer processing technology, characterized in that, Includes the following steps: S1. A SiO2 layer is deposited on the surface of a silicon substrate by CVD, and then the back side of the silicon carbide substrate is bonded to the silicon substrate. SiO2 is used to form a permanent bond between the silicon carbide substrate and the silicon substrate. S2. Complete the thinning of the silicon carbide substrate, and at the same time complete the other wafer front-side processes except for the high-temperature process; S3. Transfer the silicon carbide substrate that has completed the front wafer process to a graphite tray, then place the graphite tray into an etching pool to etch the SiO2 layer, release the permanent bond between the silicon carbide substrate and the silicon carrier, remove the silicon carrier, and then rinse the silicon carbide substrate clean. S4. High-temperature processing is carried out using a graphite tray to support a silicon carbide substrate. S5. Remove the silicon carbide substrate that has completed the high-temperature process, apply adhesive to the back of the silicon carbide substrate and bond the glass carrier, and remove the graphite tray. S6. Apply adhesive to the front and back sides of the silicon carbide substrate and bond the glass carrier plate. Use a laser to penetrate the glass carrier plate on the back side of the silicon carbide substrate to decompose the release agent, thereby debonding the glass carrier plate on the back side of the silicon carbide substrate and removing the glass carrier plate on the back side of the silicon carbide substrate. S7. Complete the back wafer fabrication process of the silicon carbide substrate; S8. Transfer the silicon carbide substrate to the cutting mold frame, use a laser to penetrate the front glass carrier of the silicon carbide substrate to decompose the release agent, debond the front glass carrier of the silicon carbide substrate, remove the front glass carrier of the silicon carbide substrate, and complete the wafer cutting.

2. The silicon carbide wafer processing technology according to claim 1, characterized in that, In step S1, multiple silicon carbide substrates are bonded to a silicon carrier at once. The specific steps are as follows: S101. Clean the silicon substrate and silicon carbide substrate, and treat the surface of the silicon substrate with plasma to activate the active bonds of the silicon substrate atoms. S102. Horizontally arrange and bond silicon carbide substrates onto the surface of a silicon substrate. S103. Place the silicon carrier plate with the silicon carbide substrate in a high-temperature furnace tube for high-temperature tempering to form a permanent bonding structure between the silicon carbide substrate and the silicon carrier plate.

3. The silicon carbide wafer processing technology according to claim 2, characterized in that, In step S103, the high-temperature tempering temperature is 800-1400℃, and the heating rate of the high-temperature furnace tube is less than 15℃ / min.

4. The silicon carbide wafer processing technology according to claim 1, characterized in that, In step S3, a groove is formed on the surface of the graphite tray corresponding to the silicon carbide substrate, and the size of the groove matches the size of the silicon carbide substrate.

5. The silicon carbide wafer processing technology according to claim 1, characterized in that, In step S3, the SiO2 layer is removed by etching, taking advantage of the different etching selectivity of the etching solution for SiO2 and Si.

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