High-quality GeTe thin film based on Te-rich target material and preparation method of high-quality GeTe thin film

Abstract

The invention provides a high-quality GeTe thin film based on a Te-rich target material and a preparation method thereof. The preparation method comprises the following steps: S1, cleaning a Si substrate by adopting a wet cleaning process; s2, depositing a SiN intermediate layer on the Si substrate to obtain a Si / SiN structure; s3, sputtering and depositing a GeTe thin film on the Si / SiN structure by adopting a Te-rich GeTe1 + x target material, and x in GeTe1 + x is 0-0.5; and S4, transferring the integral structure deposited with the GeTe film into an alloy annealing furnace, and carrying out annealing treatment at 250-300 DEG C for 20-40 minutes. According to the method, the preparation of the GeTe phase change film with high uniformity and low resistivity is realized through the component compensation and parameter regulation and control of the Te-rich target material, and an important material basis is provided for the development of high-performance semiconductor devices such as phase change memories and radio frequency switches.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor materials, and particularly relates to a high-quality GeTe thin film based on a Te-rich target and a preparation method thereof. Background Art

[0002] In the field of RF switches, traditional switch types such as MEMS, PIN diodes, and field-effect transistors have been widely used. However, with the continuous development of RF communication technology, the performance requirements for RF switches are increasing day by day, including higher switching speed, lower power consumption, smaller size, and better integration. Phase change switches are emerging as a new RF switch technology.

[0003] Currently, the phase change materials used for RF switches mainly include vanadium dioxide ( ), germanium antimony telluride (GST), and germanium telluride (GeTe). In reconfigurable RF switch applications, low on-resistance and wide dynamic range are key performance indicators. Compared with other phase change materials, GeTe exhibits a higher off / on resistance ratio during the phase change process and a faster resistance change rate at the crystallization temperature, giving it significant advantages in the field of reconfigurable RF switches. In addition, GeTe has a higher crystallization temperature relative to Therefore, GeTe thin films are considered an ideal phase change material for RF switches.

[0004] However, GeTe thin films still face many technical challenges in practical applications and need to be solved urgently. Among them, the most prominent problems include: 1. Phase change consistency problem: It is difficult to ensure the performance stability of GeTe thin films during multiple phase change processes, resulting in insufficient reliability and repeatability of the switches, which limits their application in actual RF switches.

[0005] 2. On-resistance regulation problem: The on-resistance of GeTe thin films is affected by various factors, including deposition methods, annealing conditions, and the gap width of RF metal electrodes. Research shows that the on-conductivity is approximately linearly related to parameters such as sputtering pressure, power, Ar flow rate, and annealing temperature. However, how to precisely regulate these parameters to obtain the best on-resistance still requires further research.

[0006] 3. Film uniformity problem: The uniformity of GeTe thin films directly affects their reliability as phase change switches. Although target composition compensation has a significant effect on regulating the uniformity of GeTe sputtered films, in large-scale production, the precise compensation of target composition and ensuring film uniformity are still technical difficulties.

[0007] In summary, although GeTe thin films exhibit many advantages in the field of RF switches, issues such as phase change consistency, on-resistance regulation, and film uniformity still pose key technical bottlenecks restricting their widespread application. Therefore, it is necessary to conduct in-depth research to address the above-mentioned technical problems. Summary of the Invention

[0008] Based on the above description, the present invention provides a high-quality GeTe thin film based on a Te-rich target and a preparation method thereof to solve the technical problems of phase change consistency, on-resistance regulation, and film uniformity existing in existing phase change materials.

[0009] The technical solution of the present invention to solve the above technical problems is as follows: In a first aspect, a preparation method of a high-quality GeTe thin film based on a Te-rich target includes the following steps: S1: Cleaning the Si substrate using a wet cleaning process; S2: Depositing a SiN intermediate layer on the Si substrate to obtain a Si / SiN structure; S3: Sputtering and depositing a GeTe thin film on the Si / SiN structure using a Te-rich GeTe 1+x target, where x in GeTe 1+x is 0 to 0.5; S4: Transferring the overall structure after depositing the GeTe thin film to an alloy annealing furnace and annealing it at 250 to 300 °C for 20 to 40 minutes to obtain the GeTe thin film.

[0010] Based on the above technical solution, the present invention can be further improved as follows.

[0011] Further, in step S1, the wet cleaning process is the RCA cleaning method.

[0012] Further, the RCA cleaning method includes one or more of a sulfuric acid-hydrogen peroxide mixture, diluted hydrofluoric acid, standard cleaning solution 1, and standard cleaning solution 2.

[0013] Further, in step S2, the deposition method of the SiN intermediate layer is any one of plasma-enhanced chemical vapor deposition, low-pressure chemical vapor deposition, and physical vapor deposition.

[0014] Further, in step S3, the sputtering pressure in the sputtering deposition is 0.4 to 1.0 Pa, the power is 60 to 100 W, and the Ar flow rate is 35 to 50 sccm.

[0015] Further, the thickness of the SiN intermediate layer is 55 to 70 nm; The deposition thickness of the GeTe thin film is 90 to 110 nm.

[0016] Further, the thickness of the SiN intermediate layer is 60 nm; The deposition thickness of the GeTe thin film is 100 nm.

[0017] Further, the size of the Si substrate is 6 inches.

[0018] In a second aspect, the present invention also provides a high-quality GeTe thin film based on a Te-rich target. The high-quality GeTe thin film based on a Te-rich target is prepared by using the preparation method of the high-quality GeTe thin film based on a Te-rich target as described in the first aspect, and includes: The GeTe thin film is sputtered on a Si substrate with a SiN intermediate layer.

[0019] Based on the above technical solutions, the present invention can be further improved as follows.

[0020] Further, the GeTe thin film is prepared by sputtering a Te-rich GeTe 1+x target, where x is 0 to 0.5.

[0021] The high-quality GeTe thin film based on a Te-rich target and its preparation method provided by the present invention realize the controllable preparation of the composition of the GeTe phase change thin film by adopting the composition compensation technology of the Te-rich target and combining the precise control of key parameters such as sputtering pressure, power, Ar flow rate, and post-annealing temperature. Specifically, by optimizing the above parameters, not only can the excess ratio (x value) of Te in the GeTe thin film be accurately controlled to adjust the phase change characteristics of the thin film, but also good film thickness and sheet resistance uniformity can be achieved within a 6-inch wafer surface. Experimental results show that the prepared GeTe thin film exhibits a resistivity change of up to four orders of magnitude near 190 °C. This excellent phase change characteristic makes it have broad application prospects in high-performance semiconductor device fields such as phase change memories and radio frequency switches.

[0022] Compared with the prior art, it has the following advantages: 1. Low-temperature deposition and annealing: Through technologies such as plasma-enhanced chemical vapor deposition (PECVD), the thin film deposition and annealing processes can be completed at a lower temperature, effectively avoiding potential damage to the substrate material and the structure of the deposited thin film caused by high temperature, and at the same time reducing energy consumption.

[0023] 2. Film thickness and sheet resistance uniformity: Good film thickness and sheet resistance uniformity are achieved within a 6-inch wafer surface, which is crucial for large-scale integrated circuit manufacturing and the stability of high-performance devices, and can significantly improve the consistency and reliability of the devices.

[0024] 3. Excellent phase change characteristics: The prepared GeTe thin film exhibits a resistivity change of up to four orders of magnitude near 190 °C. This characteristic not only meets the requirements of phase change memories for fast read / write speed and low power consumption but also provides excellent switching performance for applications such as RF switches, giving it significant advantages in the field of high-frequency and high-speed signal processing.

[0025] 4. Process compatibility: The preparation method of the present invention is highly compatible with existing CMOS manufacturing processes. It does not require additional complex equipment or process steps, is easy to integrate into existing production lines, and has good potential for industrial application.

[0026] In summary, through the component compensation and parameter regulation of the Te-rich target, the present invention realizes the high-performance preparation of GeTe phase change thin films, providing an important material basis for the development of high-performance semiconductor devices such as phase change memories and RF switches. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic flow chart of the preparation method of high-quality GeTe thin film based on Te-rich target provided in Embodiment 1 of the present invention; Figure 2 Map diagram of the sheet resistance Rs and film thickness THK uniformity of the high-quality GeTe thin film based on Te-rich target prepared in Embodiment 1 of the present invention; Figure 3 XRD pattern and R-T phase change characteristic test result diagram of the high-quality GeTe thin film based on Te-rich target prepared in Embodiment 1 of the present invention; Figure 4 Test result diagram of the bias test of deposition pressure on the high-quality GeTe thin film based on Te-rich target provided in the embodiment of the present invention; Figure 5 Test result diagram of the bias test of deposition power on the high-quality GeTe thin film based on Te-rich target provided in the embodiment of the present invention; Figure 6 Test result diagram of the bias test of Ar gas flow rate on the high-quality GeTe thin film based on Te-rich target provided in the embodiment of the present invention; Figure 7 Microstructure characterization diagram and analysis diagram of the high-quality GeTe thin film based on Te-rich target provided in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. Embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0029] As an emerging radio frequency (RF) switch technology, the phase change switch exhibits great application potential, especially suitable for the development of high-speed reconfigurable RF modules, due to its advantages such as easy integration with CMOS and MEMS technologies, operation at low gate voltages, high off / on ratio, fast switching speed, compact size, low parasitic capacitance, and low power consumption.

[0030] Two existing technologies are provided below for understanding the technical problems to be solved by this application: Existing technology one: Solid-phase sintering method.

[0031] Weigh high-purity Ge and Te elemental raw materials according to the stoichiometric ratio, mix them and place them in a quartz tube, which is then vacuum-sealed. Heat it for a melting reaction, and after annealing and cooling treatments, we can obtain the product. This solution is suitable for preparing GeTe-based multi-component phase change materials, with flexible variable components and facilitating doping to regulate properties.

[0032] Its existing defects are as follows: 1. High thermal threshold and a rather cumbersome preparation process; 2. Incompatible with CMOS and mainly applicable to the preparation of bulk materials.

[0033] Existing technology two: Co-sputtering of elemental targets.

[0034] Place Ge and Te elemental targets in the same chamber. By regulating the sputtering parameters of the two sets of targets, diffusion, nucleation, and growth of components are achieved on the substrate to obtain a GeTe thin film with a stoichiometric ratio. The co-sputtering solution has the advantages of high deposition rate and adjustable ratio.

[0035] Its existing defects are as follows: 1. Occupies two target positions and requires simultaneous control of the sputtering parameters of the two targets, with poor repeatability; 2. The substrate needs to be heated, and there is cross-contamination in the chamber.

[0036] The following further describes the embodiments of the present invention in detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but cannot be used to limit the scope of the present invention.

[0037] Example 1 As Figure 1 shown, this example provides a method for preparing a high-quality GeTe thin film based on a Te-rich target, including the following steps: S1. Substrate cleaning - Clean the Si substrate using a wet cleaning process Clean a 6-inch Si substrate using the RCA cleaning method. The specific steps are as follows: Treat it with a sulfuric acid-hydrogen peroxide mixture (SPM) at 120 °C for 10 minutes to remove organic pollutants; Treat with diluted hydrofluoric acid (DHF) for 1 minute to remove the surface oxide layer; Treat with the first standard cleaning solution (SC-1) at 80 °C for 10 minutes to remove particles; Treat with the second standard cleaning solution (SC-2) at 80 °C for 10 minutes to remove metal ions.

[0038] S2. Intermediate layer deposition - Deposit a 55 - 70 nm SiN intermediate layer on the Si substrate to obtain a Si / SiN structure.

[0039] Specifically, use plasma-enhanced chemical vapor deposition (PECVD) to deposit a 60 nm thick SiN intermediate layer on the Si substrate to form a Si / SiN structure.

[0040] S3. GeTe thin film deposition - Use a Te-rich GeTe 1+x target to sputter-deposit a 90 - 110 nm GeTe thin film on the Si / SiN structure, where x in GeTe 1+x is 0 - 0.5.

[0041] Specifically, use a Te-rich GeTe 1+x target (x = 0.2) to sputter-deposit a 100 nm thick GeTe thin film on the Si / SiN structure.

[0042] Among them, the sputtering conditions are: gas pressure 0.6 Pa, power 80 W, Ar flow rate 40 sccm.

[0043] S4. Annealing treatment - Transfer the overall structure after depositing the GeTe thin film to an alloy annealing furnace and anneal it at 250 - 300 °C for 20 - 40 min.

[0044] Specifically, transfer the deposited overall structure to an alloy annealing furnace and anneal it at 280 °C for 30 minutes.

[0045] In this example, by preparing a GeTe alloy target with a specific stoichiometric ratio, based on the sputtering rate difference between Ge and Te in the alloy target and the precipitation of Te after annealing, Te component compensation was carried out in the target to improve the thickness and resistivity uniformity of the GeTe film formation. At the same time, the crystalline phase GeTe component ratio after annealing is 1:1.2, close to 1:1.

[0046] Based on the component compensation of the Te-rich target, controllable preparation of the GeTe phase change thin film components was achieved through parameter regulation, as Figure 2 and Figure 3 shown, Figure 2 The figure shows the uniformity map of the sheet resistance Rs and the film thickness THK, Figure 3Shown are the XRD pattern and the test result graph of the R-T phase transition characteristics. It can be seen that the 6-inch wafer shows good film thickness and sheet resistance uniformity in-plane, and has excellent phase transition characteristics with a resistivity change of four orders of magnitude near 190°C.

[0047] It should be noted that in some alternative examples, Te-rich target composition compensation can also be carried out, and elements such as Bi, Al, Sn, and Cu are doped in the target to achieve the regulation of the crystalline resistivity and the phase transition temperature.

[0048] Example 2 This example provides another method for preparing high-quality GeTe thin films based on Te-rich targets, including the following steps: 1. Substrate cleaning The 6-inch Si substrate is cleaned by the RCA cleaning method, and the specific steps are as follows: Treat with diluted hydrofluoric acid (DHF) for 1 minute to remove the surface oxide layer; Treat with the first standard cleaning solution (SC-1) at 80°C for 10 minutes to remove particles.

[0049] 2. Intermediate layer deposition A 55-nm-thick SiN intermediate layer is deposited on the Si substrate by low-pressure chemical vapor deposition (LPCVD) to form a Si / SiN structure.

[0050] 3. GeTe thin film deposition Use Te-rich GeTe 1+x Target (x = 0.3) to sputter-deposit a 90-nm-thick GeTe thin film on the Si / SiN structure.

[0051] The sputtering conditions are: gas pressure 0.4 Pa, power 60 W, and Ar flow rate 35 sccm.

[0052] 4. Annealing treatment Transfer the deposited overall structure to an alloy annealing furnace and anneal at 250°C for 40 minutes.

[0053] The technical effects refer to the above Example 1 and will not be elaborated here.

[0054] Example 3 This example provides another method for preparing high-quality GeTe thin films based on Te-rich targets, including the following steps: 1. Substrate cleaning The 6-inch Si substrate is cleaned by the RCA cleaning method, and the specific steps are as follows: Treat with a sulfuric acid-hydrogen peroxide mixture (SPM) at 120°C for 10 minutes to remove organic contaminants; Treat with diluted hydrofluoric acid (DHF) for 1 minute to remove the surface oxide layer; Treat with the second standard cleaning solution (SC-2) at 80 °C for 10 minutes to remove metal ions.

[0055] 2. Intermediate layer deposition Deposit a 70-nm-thick SiN intermediate layer on the Si substrate by physical vapor deposition (PVD) to form a Si / SiN structure.

[0056] 3. GeTe thin film deposition Use Te-rich GeTe 1+x Target (x = 0.5) to sputter-deposit a 110-nm-thick GeTe thin film on the Si / SiN structure.

[0057] The sputtering conditions are: gas pressure 1.0 Pa, power 100 W, and Ar flow rate 50 sccm.

[0058] 4. Annealing treatment Transfer the deposited overall structure to an alloy annealing furnace and anneal it at 300 °C for 20 minutes.

[0059] Example 4 This example provides a high-quality GeTe thin film based on a Te-rich target. The GeTe thin film is sputtered on the SiN intermediate layer with a thickness of 100 nm. This GeTe thin film is prepared by sputtering with a Te-rich GeTe 1+0.2 target.

[0060] Example 5 This example provides another high-quality GeTe thin film based on a Te-rich target. The GeTe thin film is sputtered on the SiN intermediate layer with a thickness of 90 nm. This GeTe thin film is prepared by sputtering with a Te-rich GeTe 1+0.3 target.

[0061] Example 6 This example provides another high-quality GeTe thin film based on a Te-rich target. The GeTe thin film is sputtered on the SiN intermediate layer with a thickness of 110 nm. This GeTe thin film is prepared by sputtering with a Te-rich GeTe 1+0.5 target.

[0062] Effect verification I. Conduct a control experiment using targets with Ge / Te component ratios of 50:50 and 43:57. The specific parameters are as follows:

[0063] II. Conduct a bias experiment on the deposition pressure: the pressures are 0.4, 0.67, 0.93, and 1.0 Pa respectively. The obtained results are asFigure 4 as shown

[0064] III. Perform the pull - bias test of deposition power: The powers are 60, 70, 80, and 100 W respectively, and the obtained results are as Figure 5 shown

[0065] IV. Perform the pull - bias test of Ar gas flow rate: The flow rates are 35, 40, 45, and 50 sccm respectively, and the obtained results are as Figure 6 shown

[0066] V. As Figure 7 shown, combined with microstructure characterization, for the thin film prepared from the Te - rich target, the Ge / Te component ratio is close to 1:1 after annealing

[0067] After the above processes, for the high - quality GeTe thin film based on the Te - rich target, the in - plane film thickness uniformity is less than 10%, the sheet resistance uniformity is less than 10%, the crystalline resistivity is less than 10 -2 Ω·cm, and the resistivity change before and after phase change is greater than 4 orders of magnitude. Therefore, the solution of the present invention prepares a GeTe thin film with high uniformity and low resistivity - a high - quality GeTe thin film, and verifies the effectiveness of the component compensation of the Te - rich target, making it suitable for phase - change radio - frequency switches

[0068] In summary, the high - quality GeTe thin film based on the Te - rich target and the preparation method provided in the above Examples 1 to 6 all have the following technical effects 1. Low - temperature deposition and annealing: Through technologies such as plasma - enhanced chemical vapor deposition (PECVD), the thin - film deposition and annealing processes can be completed at a relatively low temperature, effectively avoiding potential damage to the substrate material and the structure of the deposited thin film caused by high temperature, and reducing energy consumption at the same time

[0069] 2. Film thickness and sheet resistance uniformity: Good film thickness and sheet resistance uniformity are achieved within a 6 - inch wafer, which is crucial for the manufacturing of large - scale integrated circuits and the stability of high - performance devices, and can significantly improve the consistency and reliability of devices

[0070] 3. Excellent phase - change characteristics: The prepared GeTe thin film exhibits a resistivity change of up to four orders of magnitude near 190°C. This characteristic not only meets the requirements of phase - change memories for fast read - write speed and low power consumption, but also provides excellent switching performance for applications such as radio - frequency switches, giving it significant advantages in the field of high - frequency and high - speed signal processing

[0071] 4. Process compatibility: The preparation method of the present invention is highly compatible with the existing CMOS manufacturing process, without the need for additional complex equipment or process steps, and is easy to integrate into the existing production line, having good potential for industrial application

[0072] In summary, through the component compensation and parameter regulation of the Te-rich target, the present invention realizes the high-performance preparation of GeTe phase change thin films, providing an important material basis for the development of high-performance semiconductor devices such as phase change memories and radio frequency switches.

[0073] In the description of this specification, the description with reference to terms such as "specific example" or "optional example" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or equivalently replace some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing high-quality GeTe thin films based on Te-rich targets, characterized in that: The following steps are involved: S1: Cleaning the Si substrate using a wet cleaning process; S2: depositing a SiN intermediate layer on the Si substrate to obtain a Si / SiN structure; S3: Using Te-rich GeTe 1+x The target material is sputtered to deposit a GeTe film on the Si / SiN structure, wherein the GeTe 1+x Where x is 0~0.5; S4: Transfer the entire structure after depositing the GeTe film to an alloy annealing furnace and anneal it at 250-300°C for 20-40 minutes.

2. The preparation method according to claim 1, characterized in that: In step S1 , the wet cleaning process is an RCA cleaning method.

3. The preparation method according to claim 2, characterized in that: The RCA cleaning method includes one or more of a sulfuric acid and hydrogen peroxide mixture, diluted hydrofluoric acid, a No. 1 standard cleaning solution, and a No. 2 standard cleaning solution.

4. The preparation method according to claim 1, characterized in that: In step S2, the SiN intermediate layer is deposited by any one of plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition and physical vapor deposition.

5. The preparation method according to claim 1, characterized in that: In step S3, the sputtering gas pressure in the sputtering deposition is 0.4-1.0 Pa, the power is 60-100 W, and the Ar flow rate is 35-50 sccm.

6. The preparation method according to claim 1, characterized in that: The thickness of the SiN intermediate layer is 55-70 nm; The deposition thickness of the GeTe film is 90-110 nm.

7. The preparation method according to claim 5, characterized in that: The thickness of the SiN intermediate layer is 60 nm; The deposition thickness of the GeTe film is 100 nm.

8. The preparation method according to claim 1, characterized in that: The size of the Si substrate is 6 inches.

9. A high-quality GeTe film based on a Te-rich target, wherein the high-quality GeTe film based on a Te-rich target is prepared by the method for preparing a high-quality GeTe film based on a Te-rich target according to any one of claims 1 to 8, characterized in that: include: The GeTe film is sputtered on a Si substrate containing a SiN intermediate layer.

10. The high-quality GeTe thin film based on Te-rich target according to claim 9, characterized in that: The GeTe film is a GeTe film rich in Te. 1+x The target material is prepared by sputtering, wherein x is 0~0.5.

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