Method of forming highly conformal amorphous carbon layer

• US 7,842,622 B1
• Filed: 05/15/2009
• Issued: 11/30/2010
• Est. Priority Date: 05/15/2009
• Status: Active Grant

• Current Assignee: ASM Japan K.K. (ASM International NV)
• Original Assignee: ASM Japan K.K. (ASM International NV)
• Inventors: Fukazawa, Atsuki, Lee, Woo-Jin
• Primary Examiner(s): WILCZEWSKI, MARY A
• Application Number:
  US12/467,017
• Publication Number:
  US 20100291713A1
• Time in Patent Office: 564 Days
• Field of Search: 438/780, 427/569, 427/249.1, 257/E21.27
• US Class Current: 438/780
• CPC Class Codes: H01L 21/02115 the material being carbon, e.g. alpha-C, diamond or hydrogen doped carbon
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• 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
• CPC Class Codes: H01L 21/3146 Carbon layers, e.g. diamond-like layers

Abstract

A method of forming a conformal amorphous hydrogenated carbon layer on an irregular surface of a semiconductor substrate includes: vaporizing a hydrocarbon-containing precursor; introducing the vaporized precursor and an argon gas into a CVD reaction chamber inside which the semiconductor substrate is placed; depositing a conformal amorphous hydrogenated carbon layer on the irregular surface of the semiconductor substrate by plasma CVD; and controlling the deposition of the conformal ratio of the depositing conformal amorphous hydrogenated carbon layer. The controlling includes (a) adjusting a step coverage of the conformal amorphous hydrogenated carbon layer to about 30% or higher as a function of substrate temperature, and (b) adjusting a conformal ratio of the conformal amorphous hydrogenated carbon layer to about 0.9 to about 1.1 as a function of RF power and/or argon gas flow rate.

Claims

1. A method of forming a conformal amorphous hydrogenated carbon layer on an irregular surface of a semiconductor substrate by plasma CVD, said irregular surface being constituted by a top surface and multiple recesses, each recess having a side wall and a bottom surface, said side wall being substantially or nearly perpendicular to the top surface, said bottom surface being substantially or nearly parallel to the top surface, said method comprising:

vaporizing a hydrocarbon-containing precursor;

introducing said vaporized precursor and an argon gas into a CVD reaction chamber inside which the semiconductor substrate is placed;

depositing a conformal amorphous hydrogenated carbon layer on the irregular surface of the semiconductor substrate by plasma polymerization of the precursor; and

controlling the deposition of the conformal ratio of the depositing conformal amorphous hydrogenated carbon layer, said controlling comprising (a) adjusting a step coverage of the conformal amorphous hydrogenated carbon layer to about 30% or higher as a function of substrate temperature, and (b) adjusting a conformal ratio of the conformal amorphous hydrogenated carbon layer to about 0.9 to about 1.1 as a function of RF power and/or argon gas flow rate,

said step coverage being defined as a ratio of an average thickness of a portion of the conformal amorphous hydrogenated carbon layer deposited on the side wall of the recess to an average thickness of a portion of the conformal amorphous hydrogenated carbon layer deposited on the top surface, said conformal ratio being defined as a ratio of a thickness of a portion of the conformal amorphous hydrogenated carbon layer deposited at a top of the side wall of the recess to a thickness of a portion of the conformal amorphous hydrogenated carbon layer deposited at a midpoint of the side wall of the recess or at a lowest point along the side wall of the recess if the lowest point is higher than the midpoint.

2. The method according to claim 1, wherein the adjusting of the step coverage is performed at a substrate temperature of about 50°

C. or lower.

3. The method according to claim 1, wherein the adjusting of the conformal ratio is performed at an RF power of about 450 W or lower.

4. The method according to claim 1, wherein the adjusting of the conformal ratio is performed at an argon gas flow rate of about 0.1 slm to about 0.8 slm.

5. The method according to claim 1, wherein the recesses are formed by photo resist patterns each having a width of 10 nm to 100 nm and a height of 10 nm to 100 nm, and arranged at intervals each being about three times the width, wherein the conformal amorphous hydrogenated carbon layer is deposited on the side wall of the recesses at a thickness which is about the same as the width of the photo resist pattern, thereby arranging the conformal amorphous hydrogenated carbon layer deposited on the side wall of the recesses at intervals each being about the same as the width of the photo resist pattern.

6. The method according to claim 1, wherein the conformal amorphous hydrogenated carbon layer is constituted by carbon and hydrogen without fluorine.

7. The method according to claim 1, wherein the conformal amorphous hydrogenated carbon layer is constituted by carbon and hydrogen without dopants.

8. The method according to claim 1, wherein the hydrocarbon-containing precursor has a carbon/hydrogen ratio (C/H) of 0.55 or higher.

9. The method according to claim 1, wherein the hydrocarbon-containing precursor is cyclic.

10. The method according to claim 9, wherein the hydrocarbon-containing precursor is cyclopenten.

11. The method according to claim 1, wherein the hydrocarbon-containing precursor is non-cyclic.

12. The method according to claim 11, wherein the hydrocarbon-containing precursor is isoprene.

13. The method according to claim 1, wherein the additional gases are helium/argon or helium/krypton.

14. The method according to claim 13, wherein the helium/argon or helium/krypton is maintained at a ratio of the molar flow rate of approximately 5:

1 to 10;

1.

15. The method according to claim 1, wherein the deposition of the amorphous hydrogenated carbon layer on the semiconductor substrate by plasma polymerization is conducted at an RF power of between approximately 10 Watt and approximately 1000 Watt, and at a reaction chamber pressure of between approximately 0.1 Torr and approximately 10 Torr.

16. The method according to claim 1, wherein the amorphous hydrogenated carbon layer depositing on the substrate has a density of more than 0.9 g/cm³.

17. The method according to claim 16, wherein the amorphous hydrogenated carbon layer depositing on the substrate has a compressive stress of between 0 and 100 MPa.