Si precursors for deposition of SiN at low temperatures

• US 10,395,917 B2
• Filed: 02/22/2018
• Issued: 08/27/2019
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: ASM IP Holding B.V. (ASM International NV)
• Original Assignee: ASM IP Holding B.V. (ASM International NV)
• Inventors: Niskanen, Antti J., Chen, Shang, Pore, Viljami, Fukazawa, Atsuki, Fukuda, Hideaki, Haukka, Suvi P.
• Primary Examiner(s): Dinke, Bitew A
• Application Number:
  US15/902,300
• Publication Number:
  US 20180366314A1
• Time in Patent Office: 551 Days
• 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 21/31111 by chemical means
• CPC Class Codes: H01L 21/823431 with a particular manufacturing method of transistors with a horizontal current flow in a vertical sidewall of a semiconductor body, e.g. FinFET, MuGFET

Abstract

Methods and precursors for depositing silicon nitride films by atomic layer deposition (ALD) are provided. In some embodiments the silicon precursors comprise an iodine ligand. The silicon nitride films may have a relatively uniform etch rate for both vertical and the horizontal portions when deposited onto three-dimensional structures such as FinFETS or other types of multiple gate FETs. In some embodiments, various silicon nitride films of the present disclosure have an etch rate of less than half the thermal oxide removal rate with diluted HF (0.5%).

Claims

1. A method of depositing a silicon nitride thin film on a substrate in a reaction space by plasma enhanced atomic layer deposition (PEALD), the method comprising:

carrying out a plurality of deposition cycles, at least one of the deposition cycles comprising;

(a) introducing a vapor-phase silicon reactant comprising silicon, iodine and hydrogen into the reaction space;

(b) flowing a purge gas through the reaction space to remove excess silicon reactant and reaction byproducts from the reaction space with the aid of a purge gas;

(c) contacting the substrate with a nitrogen plasma; and

(d) flowing a purge gas through the reaction space to remove excess nitrogen plasma and reaction byproducts from the reaction space;

wherein the reaction space comprises a susceptor and a showerhead plate with a gap of 0.5 to 5 cm between the susceptor and the showerhead plate;

wherein the nitrogen plasma is produced by applying RF power with a density of from 0.02 W/cm² to 2.0 W/cm² between the susceptor and the showerhead plate to generate a plasma in a nitrogen precursor;

wherein the silicon reactant is consumed at a rate of from 0.1 mg per deposition cycle to about 50 mg per deposition cycle; and

wherein the substrate is a 300 mm wafer.

2. The method of claim 1, wherein nitrogen is flowed continuously to the reaction space throughout the deposition cycle.

3. The method of claim 1, wherein the RF power density is from 0.05 W/cm² to 1.5 W/cm².

4. The method of claim 1, wherein the silicon reactant is consumed at a rate of from 2 mg per deposition cycle to 20 mg per deposition cycle.

5. The method of claim 1, wherein the silicon reactant comprises a precursor having the formula:

H<sub>2n+2−

y−

z−

w</sub>Si_nI_yA_zR_w

wherein, n=1-10, y=1 or more (and up to 2n+2-z-w), z=0 or more (and up to 2n+2-y-w), w=0 or more (and up to 2n+2-y-z), A is a halogen other than I, R is an organic ligand and can be independently selected from the group consisting of alkoxides, alkylsilyls, alkyl, substituted alkyl, alkylamines, and unsaturated hydrocarbon.

6. The method of claim 1, wherein the silicon reactant comprises a precursor having one of the following formulas:

(SiI₂H)NHMe, (SiI₂H)NHEt, (SiI₂H)NMe₂, (SiI₂H)NMeEt, (SiI₂H)NEt₂, (SiI₂)(NHMe)₂, (SiI₂)(NHEt)₂, (SiI₂)(NMe₂)₂, (SiI₂)(NMeEt)₂, and (SiI₂)(NEt₂)₂.

7. The method of claim 1, wherein the silicon reactant comprises H₂SiI₂.

8. The method of claim 1, wherein the nitrogen precursor is selected from the group consisting of NH₃, N₂H₄, an N₂/H₂ mixture, N₂, and any mixtures thereof.

9. The method of claim 1, wherein there is a gap of about 0.8 cm to about 3.0 cm between the showerhead and susceptor.

10. The method of claim 1, wherein the method is performed at a temperature between about 200°

C. and about 400°

C.

11. The method of claim 1, wherein the silicon nitride thin film is formed on a three-dimensional structure.

12. The method of claim 11, wherein the silicon nitride thin film exhibits a step coverage and pattern loading effect of at least about 80%.

13. The method of claim 11, wherein a ratio of an etch rate of the silicon nitride thin film in 0.5% aqueous HF on a sidewall of the three-dimensional feature to an etch rate of the silicon nitride thin film in 0.5% aqueous HF on a top surface of the three-dimensional feature is less than 2.

14. The method of claim 1, wherein an etch rate of the silicon nitride thin film is less than about 4 nm/min in 0.5% aqueous HF.

15. The method of claim 1, wherein the purge gas in step (b) comprises nitrogen.

16. The method of claim 1, wherein the purge gas in step (d) comprises nitrogen.

17. The method of claim 1, wherein the substrate is not contacted with a reactive species generated by a plasma from Ar.

18. The method of claim 1, wherein the nitrogen plasma is produced by generating the plasma in the nitrogen precursor for a first period of time, extinguishing the plasma discharge for a second period of time, and generating the plasma in the nitrogen precursor for a third period of time.

19. A plasma enhanced atomic layer deposition (PEALD) method for forming a silicon nitride thin film, the method comprising a plurality of cycles, each cycle comprising alternately and sequentially contacting a 300 mm wafer in a reaction space with a vapor phase pulse of a silicon reactant and a second reactant comprising a reactive species generated by a plasma from a nitrogen precursor,

wherein the silicon reactant comprises silicon, hydrogen and iodine;

wherein the reaction space comprises a susceptor and a showerhead plate with a gap of 0.5 to 5 cm between the susceptor and the showerhead plate;

wherein the plasma is formed by applying RF power with a density of from 0.02 W/cm² to 2.0 W/cm² between the susceptor and the showerhead plate to generate a plasma in a nitrogen precursor; and

wherein the silicon reactant is consumed at a rate of from 0.1 mg per deposition cycle to about 50 mg per deposition cycle.