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Method for a removable hard mask for patterning a low-k ILD layer

IP.com Disclosure Number: IPCOM000130468D
Publication Date: 2005-Oct-24
Document File: 3 page(s) / 62K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a removable hard mask for patterning a low dielectric constant (low-k) interlayer dielectric (ILD) layer. Benefits include improved functionality and improved performance.

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Method for a removable hard mask for patterning a low-k ILD layer

Disclosed is a method for a removable hard mask for patterning a low dielectric constant (low-k) interlayer dielectric (ILD) layer. Benefits include improved functionality and improved performance.

Background

      The conventional method for patterning a mask on an ILD layer leaves a dense high-k (greater than 4.0) material in the film stack. However, technical specifications require the use of low-k (less than 3.0) materials.

 

      During via patterning, flaring is observed on the sidewalls due to erosion by ions from the via-etch plasma.

      The conventional method can be implemented using the following steps (see Figure 1):

1.   Low-k etch-stop deposition

2.   Low-k ILD deposition

3.   Hard mask deposition
4.           Via patterning

5.   Trench patterning

6.   Barrier deposition

7.   Copper (Cu) deposition

8.   Chemical/mechanical planing (CMP)

              Dense high-k dielectric films, such as SiO2, SiN, and SiC, have lower dry-etch rates than less dense low-k ILD films. The wet etch rate of 200:1 HF of hard SiO2 is faster than that of the low-k ILD films. Additionally, via and trench clean cycles have a negligible etch rate of hard SiO2 during dual-damascene processing.

General description

      The disclosed method patterns a low-k ILD film layer using a high-k dielectric material that is selectively removed using a wet chemistry after the conventional via/trench patterning steps are complete.

              The key elements of the disclosed method include:

•             Dense dielectric material with a high-k constant material as a hard mask for via and trench patterning on low density, low-k dielectric films

•             High-k dielectric material for a hard mask that has a low dry-etch rate...