Sacrificial Underlayer for Selective Stressor Film Removal
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Solution Overview
Problem
Existing methods for making semiconductor devices with dual etch stop layer (ESL) stressor structures face challenges in selectively removing tensile and compressive stressor films without leaving residues, which can degrade device performance, especially in integrations with disposable spacers where dry etching is problematic and wet etching can gouge metal silicide layers.
Innovation Solution
The use of a sacrificial underlayer, such as a TiN film capped with an oxide hard mask film, allows for the selective removal of stressor films using a combination of wet and dry etches, ensuring complete removal without residue and protecting underlying features from etching damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching is used to remove stressor films in integrations with disposable spacers, then complete removal without residue is achieved, but gouging of metal silicide layers occurs
Solution Approach 1:
A sacrificial underlayer is introduced as an intermediary between the stressor film and the metal silicide layer. This underlayer is selectively removed to expose the stressor film for etching, while protecting the underlying metal silicide layer from direct exposure to the etching process, thereby preventing gouging while enabling complete stressor film removal
Solution Approach 2:
The sacrificial underlayer is formed in advance before the stressor film deposition. This preliminary action creates a protective barrier that prevents direct contact between subsequent etching processes and the metal silicide layer, eliminating the gouging issue while maintaining etching effectiveness
2Object-affected harmful factors
If wet etching is used to remove stressor films, then gouging of metal silicide layers is avoided, but residues remain that degrade device performance
Solution Approach 1:
The sacrificial underlayer serves as a mediator that enables the use of wet etching chemistry without direct exposure to the metal silicide layer. The underlayer is designed to be selectively removable, allowing wet etchants to completely remove the stressor film without attacking the underlying silicide, thus achieving both complete removal and protection
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the effective removal of stressor films from CMOS device regions without degrading electrical properties, maintaining performance enhancements while avoiding residues and gouging issues, particularly in integrations with severe profiles.
Implementation Method 1
The use of a sacrificial underlayer, such as a TiN film capped with an oxide hard mask film, allows for the selective removal of stressor films using a combination of wet and dry etches
Implementation Method 2
The use of a sacrificial underlayer, such as a TiN film capped with an oxide hard mask film, allows for the selective removal of stressor films using a combination of wet and dry etches
Implementation Method 3
ensuring complete removal without residue and protecting underlying features from etching damage
Data Source
AI summary
A method for making a semiconductor device is provided by (a) providing a substrate (203) having first (205) and second (207) gate structures thereon; (b) forming an underlayer (231) over the first and second gate structures; (c) removing the underlayer from the first gate structure; (d) forming a first stressor layer (216) over the first and second gate structures; and (e) selectively removing the first stressor layer from the second gate structure through the use of a first etch which is selective to the underlayer.