Method for manufacturing semiconductor device
By performing He plasma treatment on the SiN film, the problem of deterioration of antioxidant performance when the SiN film is thinned to less than 2 nm is solved, and its function as an antioxidant film is significantly improved, effectively preventing the oxidation of the Si substrate.
Patent Information
- Application Number
- CN202510143188.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2017-12-12
- Filing Date
- 2018-10-23
- Publication Date
- 2025-05-30
AI Technical Summary
When the SiN film is thinned to less than 2 nm, its antioxidant performance deteriorates, and the substrate of the SiN film cannot be fully prevented.
SiN films were formed on the substrate and treated with plasma containing He gas to enhance the antioxidant properties of the SiN film.
Through He plasma treatment, the antioxidant performance of the SiN film is enhanced, its function as an antioxidant film is improved, and the oxidation of the Si substrate is effectively suppressed.
Smart Images
Figure CN120072630A_ABST
Abstract
Description
[0001] This application is a divisional application of Chinese Patent Application No. 201811240169.9 (Title of Invention: Method for Manufacturing Semiconductor Devices; Applicant: ASM IP Holdings B.V.) filed on October 23, 2018. Technical Field
[0002] The described examples relate to a method for manufacturing semiconductor devices. Background Art
[0003] A silicon nitride (SiN) film has oxidation resistance and is used as a protective film for a substrate. The SiN film formed by the PEALD method exhibits excellent step coverage in addition to oxidation resistance, and thus it is desired to use them as an oxidation-resistant film for electrode metals and the like.
[0004] When the SiN film is thinned to less than 2 nm, the SiN film has a problem that its oxidation resistance deteriorates. That is, the SiN film having a thickness of less than 2 nm cannot sufficiently prevent the oxidation of the substrate of the SiN film. Summary of the Invention
[0005] Some examples described herein can solve the above problems. Some examples described herein can provide a method for manufacturing a semiconductor device capable of enhancing the function of a SiN film as an oxidation-resistant film.
[0006] In some examples, a method for manufacturing a semiconductor device includes forming a SiN film on a substrate and applying plasma treatment to the SiN film using a He-containing gas. Brief Description of the Drawings
[0007] Figure 1 is a diagram showing a film-forming apparatus.
[0008] Figure 2 is a timing chart showing an example of a method for manufacturing a semiconductor device.
[0009] Figure 3 is a cross-sectional view of a semiconductor device; and
[0010] Figure 4 shows transmission electron microscope images of four samples. Detailed Description
[0011] A method for manufacturing a semiconductor device according to an embodiment will be described with reference to the drawings. The same or corresponding components will be assigned the same reference numerals, and repeated descriptions may be omitted.
[0012] Figure 1FIG. 0 is a diagram showing a film forming apparatus 10 used in a method for manufacturing a semiconductor device according to an embodiment. The film forming apparatus 10 is provided with a chamber 12. A susceptor 14 and a showerhead 16 placed opposite to the susceptor 14 are provided inside the chamber 12. The susceptor 14 is configured to support a substrate 18. The substrate 18 is, for example, a Si substrate. The susceptor 14 is grounded. A space for supplying gas is formed in the showerhead 16 above the susceptor 14. The gas in the chamber 12 is exhausted from an exhaust pipe 20. A high-frequency power supply is connected to the showerhead 16 and can apply high-frequency power to the showerhead 16. The film forming apparatus 10 includes the susceptor 14 and the showerhead 16 as parallel plates and can generate capacitively coupled plasma (CCP).
[0013] A gas for film formation or treatment on the substrate 18 is supplied through the internal space of the showerhead 16 above the susceptor 18. Above the susceptor 14, a carrier gas supplied from a carrier gas source 32 and the vapor of the liquid 30a in the liquid tank 30 are supplied together through the space in the showerhead 16. The liquid 30a is a precursor for forming a SiN film. Such a precursor is, for example, SiH 2 I 2 。
[0014] An He gas source 34 is provided to supply He gas above the susceptor 14. In addition, an inert gas source 36 is provided to supply an inert gas above the susceptor 14.
[0015] Figure 2 FIG. 14 is a timing chart showing an example of a method for manufacturing a semiconductor device. This timing chart shows a period T1 for SiN film formation, a period T2 for SiN re-film formation, and a period T3 for oxide film formation.
[0016] During the period T1, a SiN film is formed on the substrate 18. The SiN film can be formed using the PE-ALD method. More specifically, first, a precursor is supplied into the chamber 12, and then a purge is performed to exhaust unnecessary materials. After that, high-frequency power (RF power) is applied to the showerhead 16, thereby generating plasma and forming a SiN film on the substrate 18. The period during which the high-frequency power is applied to the showerhead 16 is, for example, 3.3 seconds. Finally, a purge is performed to exhaust unnecessary materials. By repeating this series of processes multiple times, a SiN film is formed on the substrate 18. The thickness of the SiN film is, for example, 2 nm or less. To form a SiN film on the order of 2 nm, the above series of processes is performed on the order of 100 to 200 cycles.
[0017] Next, during the period T2, a plasma treatment using a He-containing gas is applied to the SiN film. During the period T2, at least He gas is supplied from the He gas source 34 into the chamber 12, and high-frequency power is applied to the showerhead 16 to generate plasma.
[0018] In this plasma treatment, only He can be supplied to chamber 12, or a mixed gas of He and an inert gas such as Ar or N 2 can be supplied to chamber 12. Figure 2 An example in which a mixed gas of He and N 2 is supplied to chamber 12 is shown. That is, N as a carrier gas 2 , N as a dry gas that passes through a path different from that of the carrier gas 2 and He are supplied to chamber 12. It should be noted that a path from the carrier gas source 32 to chamber 12 that does not pass through the liquid tank 30 can also be provided.
[0019] Therefore, in the plasma treatment during T2, the SiN film is treated using capacitively coupled plasma. The period T2 is, for example, on the order of 5 minutes. The RF power during period T2 can be made less than the RF power used during period T1. For example, the RF power during period T2 is on the order of half of the RF power used during period T1. The pressure in the chamber during the plasma treatment can be set to 1000 Pa or more.
[0020] Next, during period T3, an oxide film is formed on the SiN film. Any known method can be employed as the method for forming the oxide film. During period T3, for example, an SiO film is formed on the SiN film.
[0021] Figure 3 is a cross-sectional view of a semiconductor device. The top row shows the formation of a SiN film 42 on a Si substrate 40 during period T1. The SiN film 42 is very thin, for example, 2 nm or less. The middle row shows the He plasma treatment during T2. The SiN film 42 is re-formed into a SiN film 42a by He plasma radicals and ions. The SiN film 42a is considered to be a film with a higher density than the SiN film 42. It is considered that the He plasma may drive out impurities from the SiN film 42. Therefore, the SiN film 42a is considered to contain fewer impurities such as oxygen or hydrogen than the SiN film 42.
[0022] Figure 3 The bottom row in
[0023] shows the formation of an oxide film 44 on the SiN film 42 during period T3. The oxidation of the Si substrate 40 associated with the formation of the oxide film 44 is suppressed by the re-formed SiN film 42a. That is, the SiN film 42a serves as an anti-oxidation film. Figure 4 Transmission electron microscope (TEM) images of four samples are shown. The four samples have in common that a SiN film is formed on a Si substrate, but they differ in specific processing conditions.
[0024] Sample 1 shows a SiN film with a thickness of 2 nm formed by PEALD. This TEM image shows that the crystal structure of Si is maintained on the sample surface.
[0025] Sample 2 is a sample in which a SiN film with a thickness of 2 nm is formed by PEALD and then annealed at 800 °C for 5 minutes in an oxygen environment. In the TEM image of Sample 2, a perturbation of the crystal structure was observed within a range up to 1 nm from the substrate surface. This perturbation of the crystal structure means that as the substrate is oxidized, the oxygen used for annealing passes through the SiN film and the Si substrate. That is, it is considered that the surface of the Si substrate is oxidized and a SiO2 film is produced.
[0026] Sample 3 is a sample in which a SiN film with a thickness of 3 nm is formed by PEALD and then annealed at 800 °C for 5 minutes in an oxygen environment. It can be seen from the TEM image of Sample 3 that the crystal structure of Si is maintained on the sample surface. From the results of Sample 2 and Sample 3, it can be seen that if the thickness of the SiN film is 3 nm, oxidation of the Si substrate can be suppressed even during annealing, while if the SiN film is thinned to 2 nm, it is no longer possible to suppress oxidation of the SiN substrate.
[0027] Sample 4 is a sample in which a SiN film with a thickness of 2 nm is formed by PEALD and then treated with a plasma of a mixed gas of He and N 2 and then annealed at 800 °C for 5 minutes in an oxygen environment. During the treatment, it is assumed that the flow rate ratio of He and N 2 is 2:1, the pressure is 3000 Pa, the high-frequency power is 400 W, and the treatment time is 5 minutes. The difference between it and Sample 2 is that a He-containing gas is used for plasma treatment.
[0028] A comparison between the TEM image of Sample 4 and the TEM image of Sample 2 shows that although the two images have in common that the SiN film thickness is 2 nm, Sample 4 can suppress the perturbation of the crystal structure better than Sample 2. That is, in the case of Sample 4, the perturbation of the crystal structure only extends to a shallower depth from the substrate surface. Therefore, applying He gas plasma treatment to the SiN film improves the function of the SiN film as an antioxidant film. To further improve the function of the SiN film as an antioxidant film, the flow rate of the He gas can be made greater than the flow rate of the inert gas during the plasma treatment.
[0029] When only He gas is used during Figure 2 T2 in 2An inert gas is supplied to reduce the plasma density, thereby suppressing abnormal discharge. That is, an inert gas is supplied to prevent RF errors. Since various factors such as equipment configuration, gas flow rate, or RF power contribute to whether abnormal discharge occurs, if there is no possibility of abnormal discharge, the inert gas can be substantially omitted.
[0030] In some examples, providing the inert gas source 36 can adjust the flow rate ratio of He and the inert gas during T2 without adjusting the flow rate of the gas supplied from the carrier gas source 32. During T1, the He plasma treatment can also be applied multiple times in ALD. However, if the thickness of the SiN film formed during T1 is on the order of 2 nm, the necessity of the He plasma treatment in the middle of T1 is considered to be low.
[0031] According to some examples, by applying the He plasma treatment to the SiN film, the function of the SiN film as an antioxidant film can be enhanced.
Claims
1. A method for manufacturing a semiconductor device, comprising: forming a SiN film with a thickness of 2 nm or less on a substrate by using a PEALD method through a plurality of cycles without using He gas; after the SiN film with a thickness of 2 nm or less is formed on the substrate, applying plasma treatment to the SiN film using a mixture of He and an inert gas, wherein, in the plasma treatment, the flow rate of the He is made greater than the flow rate of the inert gas; and after the plasma treatment, forming an oxide film on the SiN film, wherein the RF power in the plasma treatment is less than the RF power in forming the SiN film.
2. The method for manufacturing a semiconductor device according to claim 1, wherein, The inert gas includes Ar or N 2 .
3. The method for manufacturing a semiconductor device according to claim 1, wherein the pressure in the chamber during the plasma treatment is 1000 Pa or more.
4. The method for manufacturing a semiconductor device according to claim 1, wherein capacitively coupled plasma is used in the plasma treatment.
5. The method for manufacturing a semiconductor device according to claim 1, wherein the substrate is a Si substrate.