Silicon film transfer method

Abstract

The invention relates to a method for transferring a silicon film. The method comprises the following steps of: preferably selecting an SOI (Silicon On Insulator) substrate; coating photoresist on the surface of the silicon substrate for photoetching; deep reactive ion etching is carried out, a channel leading to the buried oxide layer is etched, and photoresist removing and cleaning are carried out after etching is finished; putting the SOI substrate into hydrofluoric acid, wherein the hydrofluoric acid enters the buried oxide layer through the channel to corrode SiO2; pressing the flexible substrate on the top silicon, and separating the top silicon from the surface of the silicon substrate; and pressing the flexible substrate with the top layer silicon on the diamond according to one surface of the top layer silicon, and removing the flexible substrate to realize the transfer of the silicon film. The high-quality silicon film can be obtained at normal temperature and normal pressure, the technological process is simple, the cost is low, the success rate is high, and the method has good application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor devices, and in particular relates to a silicon thin film transfer method. Background Art

[0002] Nowadays, devices are developing towards miniaturization and increased output power, which brings a series of difficulties and challenges to solving the heat dissipation problem. Diamond has the highest thermal conductivity of all known semiconductor materials, up to 2000W·m -1 ·K -1 . Its high thermal conductivity enables it to conduct heat quickly, effectively reducing the operating temperature of the device. Based on the high thermal conductivity of diamond, the preparation of silicon-on-diamond materials and the combination of diamond and silicon-based devices can effectively improve the heat dissipation performance of the device and optimize its thermal management capabilities, thereby improving the performance and reliability of the device. Since the silicon wafer needs to be cut, thinned and other processes after bonding with the diamond to obtain a silicon-on-diamond (SOD) substrate that meets the conditions for preparing the device, many researchers have tried to transfer silicon films to diamond substrates. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for transferring silicon thin films, which can obtain high-quality silicon thin films at room temperature and pressure. The process is simple, the cost is low, the success rate is high, and the method has good application prospects.

[0004] The present invention provides a method for transferring a silicon thin film, comprising the following steps:

[0005] (1) An SOI substrate is preferably a structure comprising a silicon substrate, a buried oxide layer, and a top silicon layer;

[0006] (2) coating a photoresist on the surface of the silicon substrate and performing photolithography;

[0007] (3) performing deep reactive ion etching to etch a channel leading to the buried oxide layer, and then performing desmearing and cleaning after the etching is completed;

[0008] (4) placing the SOI substrate after step (3) in hydrofluoric acid, and the hydrofluoric acid enters the buried oxide layer through the above-mentioned channel to corrode SiO2; (5) pressing the flexible substrate on the top silicon layer to peel the top silicon layer from the surface of the silicon substrate;

[0009] (6) Press one side of the top silicon of the flexible substrate with the top silicon onto the diamond, remove the flexible substrate, and transfer the silicon film.

[0010] The photoresist in step (2) is preferably AZ5214 photoresist.

[0011] When performing deep reactive ion etching in step (3), the BOX layer of the SOI is used as a stop layer for deep reactive ion etching, and etching stops when the BOX layer is reached.

[0012] After etching SiO2 in step (4), the top silicon layer and the silicon substrate are in a virtual contact state.

[0013] The flexible substrate in step (5) is preferably polydimethylsiloxane (PDMS).

[0014] Beneficial effects

[0015] The present invention eliminates the process steps of cutting and thinning after the silicon wafer is bonded to the diamond, and high-quality silicon thin films can be obtained at room temperature and pressure. The process flow is simple, the cost is low, the success rate is high, and it has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the process of the present invention.

[0017] Figure 2 Figure 2 is a diagram of silicon thin films at different stages of the preparation process of the present invention. DETAILED DESCRIPTION

[0018] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0019] Example 1

[0020] Depend on Figure 1 As shown, this embodiment provides a method for transferring a silicon thin film, comprising the following steps:

[0021] (1) An SOI substrate is preferably a structure comprising a silicon substrate, a buried oxide layer, and a top silicon layer;

[0022] (2) coating the surface of the silicon substrate with AZ5214 photoresist and performing photolithography;

[0023] (3) performing deep reactive ion etching to etch a channel leading to the buried oxide layer, and then performing desmearing and cleaning after the etching is completed;

[0024] (4) placing the SOI substrate after step (3) in hydrofluoric acid, and the hydrofluoric acid enters the buried oxide layer through the above-mentioned channel to corrode SiO2; (5) pressing the flexible substrate on the top silicon layer to peel the top silicon layer from the surface of the silicon substrate;

[0025] (6) Pressing one side of the top silicon of the flexible substrate with the top silicon onto the diamond, removing the flexible substrate, and realizing the transfer of the (top) silicon film.

[0026] When performing deep reactive ion etching in step (3), the BOX layer of the SOI is used as a stop layer for deep reactive ion etching, and etching stops when the BOX layer is reached.

[0027] After removing SiO2, the (top) silicon film of SOI is in a virtual contact state with the silicon substrate. The silicon film can be peeled off from the silicon substrate using a flexible substrate: the flexible medium is brought into close contact with the silicon film, and then it is lifted up at a certain speed and with external force. Since the adhesion force of the flexible medium is much greater than the van der Waals force between the silicon film and the silicon substrate, the silicon film can be easily picked up from the silicon substrate at this time, thus obtaining a complete silicon film.

[0028] Depend on Figure 2 As shown, when observing the SOI after deep reactive ion etching from the front, the top Si in the channel etching area appears as a pink film; during the HF etching process, SiO2 reacts with HF to generate SiF4 gas accumulation, and a tympanic membrane phenomenon appears in some areas; after using a flexible medium to release the silicon film, it can support subsequent transfer work.

Claims

1. A method for transferring a silicon thin film, comprising the following steps: (1) An SOI substrate is preferably a structure comprising a silicon substrate, a buried oxide layer, and a top silicon layer; (2) coating a photoresist on the surface of the silicon substrate and performing photolithography; (3) performing deep reactive ion etching to etch a channel leading to the buried oxide layer, and then performing desmearing and cleaning after the etching is completed; (4) placing the SOI substrate after step (3) in hydrofluoric acid, and the hydrofluoric acid enters the buried oxide layer through the above-mentioned channel to corrode SiO2; (5) Pressing the flexible substrate onto the top silicon layer to peel the top silicon layer off the surface of the silicon substrate; (6) Press one side of the top silicon of the flexible substrate with the top silicon onto the diamond, remove the flexible substrate, and transfer the silicon film.

2. The method according to claim 1, wherein: The photoresist in step (2) is preferably AZ5214 photoresist.

3. The method according to claim 1, wherein: When performing deep reactive ion etching in step (3), the BOX layer of the SOI is used as a stop layer for deep reactive ion etching, and etching stops when the BOX layer is reached.

4. The method according to claim 1, wherein: After etching SiO2 in step (4), the top silicon layer and the silicon substrate are in a virtual contact state.

5. The method according to claim 1, wherein: The flexible substrate in step (5) is preferably polydimethylsiloxane.

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