METHODS FOR FORMING SILICON NITRIDE THIN FILMS

• US 20140273527A1
• Filed: 03/13/2013
• Published: 09/18/2014
• Est. Priority Date: 03/13/2013
• 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, Haukka, Suvi, Anttila, Jaakko
• Granted Patent: US 10,573,511 B2
• Time in Patent Office: Days
• US Class Current: 438/792
• 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: C23C 16/45553 characterized by the use of precursors specially adapted for ALD
• 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

Abstract

The present invention relates to methods of forming silicon nitride thin films on a substrate in a reaction chamber by plasma enhanced atomic layer deposition (PEALD). Exemplary methods include the steps of (i) introducing an octahalotrisilane Si₃X₈ silicon precursor, such as octachlorotrisilane (OCTS) Si₃Cl₈, into a reaction space containing a substrate, (ii) introducing a nitrogen containing plasma into the reaction space, and wherein steps (i), (ii) and any steps in between constitute one cycle, and repeating said cycles a plurality of times until an atomic layer nitride film having a desired thickness is obtained.

Claims

1. A method of forming a silicon nitride film by plasma enhanced atomic layer deposition (PEALD) comprising the steps of;

i. introducing an octahalotrisilane Si₃X₈ silicon precursor into a reaction space containing a substrate,

ii. introducing a nitrogen containing plasma into the reaction space,

iii. wherein steps (i), (ii) and any steps in between constitute one cycle, and repeating said cycles a plurality of times until a film comprising silicon nitride having a desired thickness is obtained.

2. A method in accordance with claim 1, wherein the X of said octahalotrisilane Si₃X₈ is a halide selected from the group of Cl, F and Br.

3. A method in accordance with claim 1, wherein the octahalotrisilane Si₃X₈ silicon precursor is octachlorotrisilane (OCTS).

4. A method in accordance with claim 1, further comprising keeping the reaction space at a temperature between 50-250°

C.

5. A method in accordance with claim 1, further comprising keeping the reaction space at a temperature below 150°

C.

6. A method in accordance with claim 1, further comprising keeping the reaction space pressure between 1-10 torr while introducing a nitrogen containing plasma into the reaction space.

7. A method in accordance with claim 4, wherein the nitrogen containing plasma also contains hydrogen and is formed by either N₂/H₂ or NH₃.

8. A method in accordance with claim 3, wherein no catalyst is introduced into the reaction space between, or before, steps (i) and (ii).

9. A method in accordance with claim 2, wherein step (i) is self limiting.

10. A method in accordance with claim 2, further comprising a purge step between steps (i) and (ii) for removing excess silicon precursor and any reaction byproducts from the reaction chamber.

11. A method in accordance with claim 2, further comprising a first purge step between steps (i) and (ii) and a second purge step after step (ii), wherein each of said purge steps are for removing excess silicon precursor gases formed in plasma discharge as well as any reaction byproducts from the reaction chamber.

12. A method in accordance with claim 10, wherein each iteration of step (i) produces less than 2 molecular layers of the silicon precursor.

13. A method in accordance with claim 10, wherein each iteration of step (i) produces less than about 1 molecular layers of the silicon precursor.

14. A method in accordance with claim 2, wherein the silicon precursor is introduced in its vapor stage.

15. A method in accordance with claim 1, further comprising keeping the reaction chamber is at a temperature of less than 400°

C.

17. A method in accordance with claim 12, wherein the X of said octahalotrisilane Si₃X₈ is a halide selected from the group of Cl, F and Br.

18. A method in accordance with claim 12, wherein the octahalotrisilane Si₃X₈ silicon precursor is octachlorotrisilane (OCTS).

19. A method in accordance with claim 12, wherein the octahalotrisilane is introduced at a temperature below 100°

C.

16. A method of forming a silicon nitride film by plasma enhanced atomic layer deposition (PEALD) comprising the steps of;

i. introducing an octahalotrisilane Si₃X₈ silicon precursor into a reaction space containing a substrate,

ii. creating a nitrogen containing plasma within the reaction space,

iii. wherein steps (i), (ii) and any steps in between constitute one cycle, and repeating said cycles a plurality of times until a film comprising silicon nitride having a desired thickness is obtained.