Organic low K dielectric etch with NH3 chemistry

• US 6,743,732 B1
• Filed: 01/26/2001
• Issued: 06/01/2004
• Est. Priority Date: 01/26/2001
• Status: Expired due to Fees

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Chao, Li-Chih, Tsai, Chia-Shiung, Lin, Li-Te
• Primary Examiner(s): Vinh, Lan
• Application Number:
  US09/769,812
• Time in Patent Office: 1,222 Days
• Field of Search: 438/706, 438/710, 438/712, 438/714, 438/720, 216/37, 216/67
• US Class Current: 438/706
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/76802 by forming openings in dielectrics
• CPC Class Codes: H01L 21/76811 involving multiple stacked pre-patterned masks
• CPC Class Codes: H01L 21/76813 involving a partial via etch

Abstract

A plasma etch process for organic low-k dielectric layers using NH₃ only, or NH₃/H₂ or NH₃/H₂ gases. A low k dielectric layer is formed over a substrate. A masking pattern is formed over the low k dielectric layer. The masking pattern has an opening. Using the invention'"'"'s etch process, the low k dielectric layer is etched through the opening using the masking pattern as an etch mask. In a first embodiment, the etch process comprises: etching the low k dielectric layer by applying a plasma power and flowing only NH₃ gas. In a second embodiment, the etch process comprises: etching the low k dielectric layer by applying a plasma power and flowing only NH₃/H₂ gas. In a third embodiment, the etch process comprises: etching the low k dielectric layer by applying a plasma power and flowing only NH₃/N₂ gas. The invention'"'"'s NH₃ containing plasma etch etches organic Low k materials unexpectedly fast. The invention'"'"'s NH₃ only etch had a 30 to 80% high etch rate than N₂/H₂ etches of low-k materials like Silk™.

Claims

1. A method of fabrication of etching a low-k dielectric layer, comprising the steps of:

a) forming an organic low-k dielectric layer over an insulation layer over a substrate;

b) forming a masking pattern over said organic low k dielectric layer;

said masking pattern having an opening;

c) using an etch process to etch said organic low k dielectric layer through said opening to form a first opening using said masking pattern as an etch mask;

said etch process comprising;

(1) in a first step, etching said organic low k dielectric layer by applying a plasma power and flowing NH₃ and H₂ etch gasses and flowing O₂ or CO gasses.

2. The method of claim 1 wherein said first step comprises:

a plasma power between 500 and 1500 W, plasma power plasma density between 1E9 and 1E11 cm<sup>−

3</sup>, a NH₃ flow between 50 and 300 sccm, a H₂ flow between 50 and 300 sccm and a pressure between 80 and 800 mTorr and flowing O₂ or CO gasses.

3. The method of claim 1 wherein said organic low k dielectric is comprised of a material selected from the group consisting of fluorinated arylether, Benzocyclobuthene (BCB), amorphous teflon, carbon doped oxides, poly arylene ether (PAE) and organic Spin on materials.

4. The method of claim 1 wherein said organic low k dielectric is comprised of a material selected from the group consisting of fluorinated arylether, and poly arylene ether.

5. The method of claim 1 wherein said organic low k dielectric is comprised of carbon doped oxide.

6. The method of claim 1 wherein said organic low k dielectric is comprised of poly arylene ether (PAE).

7. The method of claim 1 wherein said etch forms said first opening through said organic low k dielectric layer;

said first opening having sidewalls defined by said organic low k dielectric layer;

said sidewalls are substantially vertical at a angle between 87 and 93 degrees to the surface of the substrate; and

said first step comprises;

a plasma power between 500 and 1500 W, plasma power plasma density between 1E9 and 1E11 cm<sup>−

3</sup>, a NH₃ flow between 50 and 300 sccm, a H₂ flow between 50 and 300 sccm and a pressure between 80 and 800 mTorr and flowing O₂ or CO gasses.