METHOD TO MINIMIZE WET ETCH UNDERCUTS AND PROVIDE PORE SEALING OF EXTREME LOW K (K<2.5) DIELECTRICS

• US 20110092077A1
• Filed: 12/22/2010
• Published: 04/21/2011
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: WITTY, DEREK, XIA, LI-QUN, SHEK, MEI-YEE, XU, HUIWEN, M'SAAD, HICHEM, AL-BAYATI, AMIR
• Granted Patent: US 8,445,075 B2
• Time in Patent Office: Days
• US Class Current: 438/763
• CPC Class Codes: C23C 16/308 Oxynitrides
• CPC Class Codes: C23C 16/401 containing silicon
• CPC Class Codes: H01L 21/02126 the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• 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 21/02274 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 21/3122 layers comprising polysiloxane compounds
• CPC Class Codes: H01L 21/31612 on a silicon body
• CPC Class Codes: H01L 21/31633 Deposition of carbon doped silicon oxide, e.g. SiOC
• CPC Class Codes: H01L 21/76829 characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
• CPC Class Codes: H01L 21/76831 in via holes or trenches, e.g. non-conductive sidewall liners
• CPC Class Codes: H01L 21/76834 formation of thin insulating films on the sidewalls or on top of conductors H01L21/76831 takes precedence

Abstract

Methods of processing films on substrates are provided. In one aspect, the methods comprise treating a patterned low dielectric constant film after a photoresist is removed form the film by depositing a thin layer comprising silicon, carbon, and optionally oxygen and/or nitrogen on the film. The thin layer provides a carbon-rich, hydrophobic surface for the patterned low dielectric constant film. The thin layer also protects the low dielectric constant film from subsequent wet cleaning processes and penetration by precursors for layers that are subsequently deposited on the low dielectric constant film.

Claims

1. A method of treating a substrate having a low k layer comprising silicon and carbon, wherein the surface of the low k layer has a reduced carbon content after an etching process comprising exposure to a oxygen-containing plasma, the method comprising:

depositing a second layer comprising silicon and carbon on the low k layer.

2. The method of claim 1, wherein the second layer is deposited using the same precursors used to deposit the low k layer.

3. The method of claim 1, wherein the second layer has a thickness between about 4 Å

and about 100 Å

.

4. The method of claim 1, wherein the second layer has a carbon content of between about 5 atomic % and about 30 atomic %.

5. The method of claim 1, further comprising wet cleaning the substrate without loss of critical dimension.

6. The method of claim 1, wherein the second layer leaves a conformal, carbon-rich surface on the low k layer.

7. The method of claim 6, wherein the second layer has a density higher than the low k layer.

8. The method of claim 6, wherein the second layer is a pore-sealing layer.

9. A method of forming a patterned semiconductor substrate, comprising:

forming a low k layer comprising carbon on the substrate;

forming a patterning layer over the low k layer;

patterning the low k layer;

removing the patterning layer, and forming a depleted-carbon surface on the low k layer by exposing the substrate to a plasma comprising oxygen;

recovering the carbon content of the depleted-carbon surface by depositing a thin, conformal, carbon-containing layer over the depleted-carbon surface; and

then

wet cleaning the substrate without loss of critical dimension.

10. The method of claim 9, wherein the low k layer is a porous low k layer.

11. The method of claim 9, wherein depositing the thin, conformal, carbon-containing layer over the depleted-carbon surface comprises performing a PECVD process using the same precursors used to deposit the low k layer comprising carbon on the substrate.

12. The method of claim 9, wherein the thin, conformal, carbon-containing layer has a thickness between about 4 Å

and about 100 Å

.

13. The method of claim 9, wherein the thin, conformal, carbon-containing layer has a density higher than the low k layer.

14. The method of claim 9, wherein the thin, conformal, carbon-containing layer is a pore-sealing layer.

15. A method of forming a patterned layer on a semiconductor substrate, comprising:

depositing a porous, low k layer comprising silicon and carbon on the substrate by performing a PECVD process using an organosilicon precursor and a porogen on the substrate and post-treating the substrate to remove the porogen;

patterning the porous, low k layer by forming a photoresist layer over the low k layer, patterning the photoresist layer, and transferring the pattern through the low k layer;

removing the photoresist layer, and depleting the carbon concentration of a surface of the low k layer, by ashing with a plasma comprising oxygen; and

recovering the carbon concentration of the surface of the low k layer by depositing a thin, dense layer comprising silicon and carbon directly on the low k layer.

16. The method of claim 15, wherein the thin, dense layer comprising silicon and carbon is a pore-sealing layer with a thickness between about 4 Å

and about 100 Å

.