Plasma enhanced atomic layer deposition (PEALD) of SiN using silicon-hydrohalide precursors

• US 10,580,645 B2
• Filed: 04/30/2018
• Issued: 03/03/2020
• Est. Priority Date: 04/30/2018
• Status: Active Grant

• Current Assignee: ASM IP Holding B.V. (ASM International NV)
• Original Assignee: ASM IP Holding B.V. (ASM International NV)
• Inventors: Ueda, Shinya, Ebisudani, Taishi, Suzuki, Toshiya
• Primary Examiner(s): Malek, Maliheh
• Application Number:
  US15/966,717
• Publication Number:
  US 20190333753A1
• Time in Patent Office: 673 Days
• CPC Class Codes: C23C 16/045 Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
• CPC Class Codes: C23C 16/345 Silicon nitride
• CPC Class Codes: C23C 16/4554 Plasma being used non-continuously in between ALD reactions C23C16/56 takes precedence
• CPC Class Codes: H01L 21/0217 the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/02211 the compound being a silane, e.g. disilane, methylsilane or chlorosilane
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/0228 deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD
• CPC Class Codes: H01L 21/02315 treatment by exposure to a plasma
• CPC Class Codes: H01L 21/0337 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment

Abstract

Methods for forming silicon nitride films are provided. In some embodiments, silicon nitride can be deposited by atomic layer deposition (ALD), such as plasma enhanced ALD. One or more silicon nitride deposition cycle comprise a sequential plasma pretreatment phase in which the substrate is sequentially exposed to a hydrogen plasma and then to a nitrogen plasma in the absence of hydrogen plasma, and a deposition phase in which the substrate is exposed to a silicon precursor. In some embodiments a silicon hydrohalide precursors is used for depositing the silicon nitride. The silicon nitride films may have a high side-wall conformality and in some embodiments the silicon nitride film may be thicker at the bottom of the sidewall than at the top of the sidewall in a trench structure. In gap fill processes, the silicon nitride deposition processes can reduce or eliminate voids and seams.

Claims

1. A method of depositing a SiN thin film on a three-dimensional structure on a substrate in a reaction space by an atomic layer deposition (ALD) process comprising a plurality of deposition cycle comprising:

a sequential plasma pretreatment phase comprising;

contacting the substrate with a first hydrogen plasma; and

after contacting the substrate with the first hydrogen plasma, contacting the substrate with a second nitrogen plasma in the absence of hydrogen plasma; and

a silicon nitride deposition phase comprising alternately and sequentially contacting the substrate with a silicon hydrohalide precursor and a nitrogen reactant.

2. The method of claim 1, wherein contacting the substrate with the first hydrogen plasma comprises simultaneously contacting the substrate with the first hydrogen plasma and a nitrogen plasma.

3. The method of claim 1, wherein the sequential plasma pretreatment phase is carried out in each deposition cycle.

4. The method of claim 1, wherein the first hydrogen plasma is generated with a first power and the second nitrogen plasma is generated with a second power that is less than or equal to the first power.

5. The method of claim 1, wherein the second nitrogen plasma is formed in N₂ gas.

6. The method of claim 1, wherein the SiN film has a step coverage of about 100% to about 300% on the three-dimensional structure.

7. The method of claim 1, wherein the three-dimensional structure on the substrate has an aspect ratio (AR) of greater than or equal to 3.

8. The method of claim 7, wherein the three-dimensional structure comprises a side-wall, and the side-wall conformality of the SiN film is greater than 100%.

9. A plasma enhanced atomic layer deposition (PEALD) method for depositing SiN over a three-dimensional structure on a substrate in a reaction space comprising a deposition cycle comprising, in order:

a sequential preplasma pretreatment phase comprising;

contacting the substrate with a first plasma generated in a mixture of H₂ and N₂ gas; and

contacting the substrate with a second plasma generated in N₂ gas in the absence of H₂ gas; and

a deposition phase comprising contacting the substrate with a silicon precursor,

wherein the deposition cycle is repeated two or more times sequentially.

10. The method of claim 9, wherein the first plasma is generated at a first plasma power and the second plasma is generated at a second plasma power that is lower than the first power.

11. The method of claim 9, wherein the silicon precursor comprises a silicon hydrohalide.

12. The method of claim 9, further comprising purging the reaction space prior to contacting the substrate with the silicon precursor and after contacting the substrate with the first plasma and the second plasma.

13. The method of claim 9, wherein N₂ gas is flowed into the reaction space continuously throughout the deposition cycle.

14. The method of claim 9, wherein the three-dimensional structure comprises a trench with side walls and a top region and the SiN film has a side-wall conformality of greater than 100%.

15. The method of claim 9, wherein the SiN film has a ratio of a wet etch rate (WER) in dilute HF of the silicon nitride thin film on the sidewalls of the three-dimensional feature to a wet etch rate (WER) in dilute HF of the silicon nitride thin film on a top region of the three-dimensional feature of about 0.02 to about 3.0.

16. A method of depositing SiN by plasma enhanced atomic layer deposition (PEALD) on a substrate in a reaction space comprising a plurality of deposition cycles comprising:

contacting the substrate with a first plasma generated by applying a first plasma power to a gas comprising hydrogen and nitrogen; and

subsequently contacting the substrate with a second plasma generated by applying a second plasma power to a gas comprising nitrogen but not hydrogen; and

a deposition phase comprising alternately and sequentially contacting the substrate with a silicon halide and a nitrogen precursor.

17. The method of claim 16, wherein the second power is less than the first power.

18. The method of claim 16, wherein the silicon reactant is a silicon hydrohalide.

19. The method of claim 16, wherein the first plasma power is greater than or equal to the second plasma power.

20. The method of claim 16, wherein the SiN is deposited on a trench having an aspect ratio of greater than 3 and has a conformality of greater than 100%.