Chemical vapor deposition method

Abstract

The present application relates to the technical field of semiconductor manufacturing. Disclosed is a chemical vapor deposition method. The chemical vapor deposition method comprises: S100, providing a substrate having a trench, and arranging the substrate in a reaction chamber; S200, performing a deposition operation, the deposition operation being configured to supply a reaction gas into the reaction chamber, and a product generated from a reaction of the reaction gas being deposited as a film layer on the surface of the substrate and in the trench of the substrate; S300, stopping introducing the reaction gas, and performing a blowing operation, the blowing operation being configured to blow into the trench of the substrate or discharge out of the reaction chamber the product that is not adsorbed to the surface of the substrate and the opening of the trench of the substrate, while retaining the unadsorbed product in the trench; and S400, repeating steps S200 and S300, so as to deposit a film layer of a predetermined thickness. The present method is less likely to seal openings of trenches ahead during filling processes, so as to reduce voids formed in the trenches, thus improving the quality of film layer deposition.

Description

Chemical vapor deposition method TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, and in particular to a chemical vapor deposition method. BACKGROUND

[0002] A conventional chemical vapor deposition (CVD) technique has a serious problem in processing a substrate with a high aspect ratio recess, i.e., in the process of depositing a film layer, the filling capacity of the recess is insufficient, and the product of the reaction gas tends to form a film on the upper part of the recess rather than sufficiently filling the deep part of the recess. This deficiency leads to the upper end of the recess being prematurely sealed, forming a void. This phenomenon can cause serious defects in substrate manufacturing, affecting the performance and reliability of the device. SUMMARY

[0003] The present application provides a chemical vapor deposition method, which is beneficial to reduce the formation of voids in the recess of a substrate.

[0004] The present application solves the above technical problems by the following technical solutions:

[0005] A chemical vapor deposition method, comprising:

[0006] S100, providing a substrate with a recess, and placing the substrate in a reaction chamber;

[0007] S200, performing a deposition operation configured to provide a reaction gas into the reaction chamber, and the product after reaction of the reaction gas deposits a film layer on the surface of the substrate and in the recess of the substrate;

[0008] S300, stopping the introduction of the reaction gas, and performing a purge operation configured to blow the product not adsorbed on the surface of the substrate and at the opening of the recess of the substrate into the recess of the substrate or out of the reaction chamber, and to retain the unadsorbed product in the recess;

[0009] S400, repeating steps S200 and S300 to deposit a film layer of a predetermined thickness.

[0010] The positive progress effect of the present application is that after the reaction gas is decomposed by heat, part of the products is adsorbed and deposited on the surface and the groove of the substrate to form a film layer, and the other part of the products is not adsorbed on the substrate. For the products not adsorbed on the substrate, the products located above the surface of the substrate or at the opening of the groove of the substrate are more easily blown away than the products located in the groove of the substrate. By performing the blowing operation, the products not adsorbed at the opening of the groove of the substrate can be blown into the groove of the substrate or discharged from the reaction chamber, and the unadsorbed products in the groove are retained. During the blowing operation, there is almost no film layer deposited at the opening of the groove of the substrate, and part or all of the unadsorbed products in the groove continue to be deposited into a film, which is beneficial to create a process window for the bottom-up filling of the film layer in the groove. By adopting the deposition and blowing cycle to deposit the film layer, the deposition rate at the opening of the groove is reduced, the deposition rate inside the groove is improved, the groove is not easy to be sealed early in the filling process, the formation of cavities in the groove is reduced, and the quality of the film layer deposition is improved.

[0011] SUMMARY

[0012] The features and performances of the present application are further described by the following examples and drawings.

[0013] Fig. 1 is a flow chart of a chemical vapor deposition method of the present application;

[0014] Fig. 2 is a schematic diagram showing the distribution of products in the groove during the stage of providing reaction gas of the present application;

[0015] Fig. 3 is a schematic diagram showing the distribution of products in the groove during the blowing stage of the present application;

[0016] Fig. 4 is a schematic diagram showing the distribution of products in the groove during the stage of providing reaction gas again of the present application;

[0017] Fig. 5 is a schematic diagram showing the distribution of products in the groove during the blowing stage again of the present application;

[0018] Fig. 6 is a schematic diagram showing the distribution of products in the groove after the deposition of the present application is completed;

[0019] Fig. 7 is a process timing chart of the chemical vapor deposition method of the present application.

[0020] Preferred embodiments of the present application

[0021] The present application will be further described by way of examples without limiting the present application to the examples.

[0022] As shown in Fig. 1, the present application provides a chemical vapor deposition method, comprising:

[0023] S100, providing a substrate with a groove and placing the substrate in a reaction chamber;

[0024] S200, performing a deposition operation, the deposition operation being configured to provide a reaction gas into the reaction chamber, the reaction gas after reaction generating a product, the product being deposited into a film layer on the surface of the substrate and in the recess of the substrate;

[0025] S300, stopping the reaction gas from being provided, and performing a purge operation, the purge operation being configured to blow the product not adsorbed on the surface of the substrate and at the opening of the recess of the substrate into the recess of the substrate or out of the reaction chamber, and to retain the product in the recess;

[0026] S400, repeating steps S200 and S300 to deposit a film layer of a predetermined thickness.

[0027] As shown in FIG. 2, in step S100, a part of the product 600 is adsorbed and deposited into a film layer on the surface 520 of the substrate and in the recess 510 of the substrate, and another part of the product 600 is not adsorbed on the substrate and is in a suspended state. For the product 600 not adsorbed on the substrate, the product 600 located above the surface 520 of the substrate or at the opening of the recess 510 of the substrate is more likely to be blown away than the product 600 located in the recess 510 of the substrate. By performing a purge operation, as shown in FIG. 3, the product 600 not adsorbed on the surface 520 of the substrate and at the opening of the recess 510 of the substrate can be blown into the recess 510 of the substrate or out of the reaction chamber, and the product 600 not adsorbed in the recess 510 (i.e., the product 600 in a suspended state in the recess 510 is at least partially retained in the recess 510) is retained in the recess 510. The retention can be full retention or partial retention. During the purge operation, there is almost no film layer deposition at the opening of the recess 510 of the substrate because there is substantially no product not adsorbed, and part or all of the product 600 not adsorbed in the recess 510 continues to be deposited into a film layer, which is beneficial to create a process window for the film layer filling from bottom to top in the recess 510. As shown in FIG. 4, step S200 is performed again, the thickness of the film layer gradually increases, the opening of the recess 510 is not closed, and the product 600 can enter the inside of the recess 510, which improves the filling ability of the product 600 to the recess 510. As shown in FIG. 5, step S300 is performed again to blow the product 600 not adsorbed at the opening of the recess 510 of the substrate into the recess 510 of the substrate or out of the reaction chamber. The deposition and purge cycle is adopted to deposit the film layer, which is beneficial to reduce the deposition rate at the opening of the recess 510 and improve the deposition rate inside the recess 510, as shown in FIG. 6, the recess 510 is not easy to be closed early in the filling process, the formation of a cavity in the recess 510 is reduced, and the quality of the film layer deposition is improved.

[0028] In the embodiment, step S300 further includes stopping the purge operation and performing a vacuumizing operation.

[0029] After the purge operation is stopped, some of the products can still be suspended in the reaction chamber and fail to be discharged from the reaction chamber in time, and can be subsequently deposited again on the substrate surface, affecting the deposition quality. Through the vacuum pumping operation, the products and impurities generated in the reaction process can be further pumped out, thereby improving the film deposition quality of the subsequent film layer.

[0030] In the present embodiment, the reaction gas includes any one of SiH4, SiH4+PH3, SiH4+BH3, TEOS (tetraethoxysilane), or TEOS+O2. The reaction gas SiH4 is used to deposit a polysilicon (product) film layer, the reaction gas SiH4+PH3 (a mixed gas of SiH4 and PH3) is used to form a phosphorus-doped polysilicon (product) film layer, the reaction gas SiH4+BH3 (a mixed gas of SiH4 and BH3) is used to form a boron-doped polysilicon (product) film layer, and the reaction gas TEOS or TEOS+O2 (a mixed gas of TEOS and O2) is used to deposit a silicon oxide (product) film layer. Among them, the above reaction gases are used to deposit film layers on the silicon wafer through thermal decomposition.

[0031] In the present embodiment, the pressure in the reaction chamber during the purge operation is not higher than 1 Torr. During the purge operation, the exhaust capacity is increased to maintain a low pressure in the reaction chamber, thereby accelerating the discharge of the products that are not adsorbed above the substrate or at the opening of the groove 510 of the substrate.

[0032] In the present embodiment, the purge gas used in the purge operation is nitrogen or an inert gas.

[0033] As shown in FIG. 3, further, the purge gas blowing direction in the purge operation is parallel to the extension direction Y of the groove. During the purge operation, it is more conducive to blowing the products that are not adsorbed at the opening of the groove 510 into the groove 510, thereby reducing the film deposition rate at the opening of the groove 510, increasing the film deposition rate inside the groove, and further reducing the probability of premature sealing of the groove during film deposition.

[0034] In some embodiments, the blowing direction of the purge gas is not limited thereto, and can be flexibly arranged according to the limitations of the equipment or the requirements of the process, such as being perpendicular to the extension direction of the groove or being at a certain angle with the groove, etc.

[0035] After the purge operation is performed, the concentration of the unadsorbed products in the groove of the substrate is higher than the concentration of the unadsorbed products on the surface of the substrate.

[0036] In the embodiment, the length of the deposition operation in each cycle is inversely proportional to the aspect ratio of the groove of the substrate. The greater the aspect ratio of the groove of the substrate, the easier the groove is to be closed in advance during the deposition of the film layer. The greater the aspect ratio of the groove, the shorter the length of the deposition operation in each cycle, so as to reduce the thickness of the film layer deposited in each cycle, thereby preventing the groove from being closed in advance. The smaller the aspect ratio of the groove, the less likely the groove is to be closed in advance, and the length of the deposition operation in each cycle can be appropriately increased, thereby improving the deposition efficiency of the film layer.

[0037] In the embodiment, the length of the deposition operation in each cycle is inversely proportional to the deposition rate of the film layer. The higher the deposition rate of the film layer, the shorter the length of the deposition operation in each cycle, so as to reduce the thickness of the film layer deposited in each cycle, thereby preventing the groove from being closed in advance. The lower the deposition rate of the film layer, the length of the deposition operation in each cycle can be appropriately increased, thereby improving the deposition efficiency of the film layer.

[0038] As shown in FIG. 7, the chemical vapor deposition method provided by the application further includes increasing the length T1 of the deposition operation in each cycle with the increase of the number of cycles. With the increase of the number of cycles, the groove is gradually filled, and thus the aspect ratio of the groove gradually decreases. Therefore, the length of the deposition operation can be appropriately increased after each cycle, that is, the length of step S200 is increased, thereby improving the deposition efficiency of the film layer.

[0039] In some embodiments, the length of the deposition operation in the next cycle is not necessarily increased after each cycle, but can be increased after a plurality of cycles.

[0040] In the embodiment, when the steps S200 and S300 are executed until the cumulative length of the deposition operation reaches a preset value, the purge operation is stopped in the subsequent operation, and only the deposition operation is performed. The deposition rate of the film layer can be obtained through preliminary experiments, and thus the deposition thickness of the film layer can be obtained according to the cumulative length of the deposition operation. The preset value is set to make the aspect ratio of the groove reach a certain value, so that the groove can be completely filled by only the deposition operation in the subsequent operation, without generating a hollow.

[0041] In the embodiment, the length T2 of the purge operation and the length T3 of the vacuumizing operation in each cycle are fixed.

[0042] In the embodiment, the specific lengths of T1, T2 and T3 are not limited, and the specific lengths of T1, T2 and T3 are determined by specific processes.

[0043] In some embodiments, only the deposition operation and the purge operation can be performed, and the vacuumizing operation is not required.

[0044] Although the specific embodiments of the application are described above, it should be understood that the scope of protection of the present application is not limited to the specific embodiments described above. Those skilled in the art can make various changes or modifications to the embodiments without departing from the principles and spirit of the present application, and such changes and modifications are also within the scope of protection of the present application.

Claims

1. A chemical vapor deposition method, characterized in that, include: S100: Provide a substrate with a groove and place the substrate inside the reaction chamber; S200, Perform a deposition operation, the deposition operation being configured to provide a reaction gas into the reaction chamber, the reaction gas passing through the reaction product to deposit a film layer on the surface of the substrate and in the grooves of the substrate; S300, Stop the flow of reaction gas and perform a purging operation, wherein the purging operation is configured to blow the products that are not adsorbed on the surface of the substrate and the groove opening of the substrate into the groove of the substrate or out of the reaction chamber, while retaining the unadsorbed products in the groove; S400, cyclic steps S200 and S300 are performed to deposit a film of a predetermined thickness.

2. The chemical vapor deposition method as described in claim 1, characterized in that, Step S300 also includes stopping the purging operation and performing a vacuuming operation.

3. The chemical vapor deposition method as described in claim 1, characterized in that, It also includes increasing the duration of the deposition operation in a single cycle as the number of cycles increases.

4. The chemical vapor deposition method as described in claim 1, characterized in that, It also includes stopping the purging operation and only performing the deposition operation when the cumulative duration of the deposition operation reaches a preset value after repeatedly executing steps S200 and S300.

5. The chemical vapor deposition method as described in claim 1, characterized in that, The reacting gas includes any one of SiH4, SiH4+PH3, SiH4+BH3, TEOS, or TEOS+O2.

6. The chemical vapor deposition method as described in claim 1, characterized in that, The pressure in the reaction chamber during the purging operation shall not exceed 1 Torr.

7. The chemical vapor deposition method as described in claim 1, characterized in that, The duration of the deposition operation in a single cycle is inversely proportional to the aspect ratio of the groove in the substrate.

8. The chemical vapor deposition method as described in claim 1, characterized in that, The duration of the deposition operation in a single cycle is inversely proportional to the deposition rate of the film.

9. The chemical vapor deposition method as described in claim 1, characterized in that, The purging gas used in the purging operation is nitrogen or an inert gas.

10. The chemical vapor deposition method as described in claim 1, characterized in that, The purging gas in the purging operation is purged in a direction parallel to the extension direction of the groove.

Images