Sacrificial Oxide Capping for Contact Etch Damage Protection
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Solution Overview
Problem
The aggressive nature of dry etch processes, such as reactive ion etching, can cause damage to semiconductor device layers, leading to uncontrolled variations in electrical performance and yield loss.
Innovation Solution
A method involving the formation of a sacrificial oxide capping layer on semiconductor regions using a plasma etching process with specific etching gases, which protects the regions from damage during etching and can be subsequently removed without harming the underlying material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dry etch process is used to open contacts, then etching efficiency is improved, but damage to underlying material increases
Solution Approach 1:
A sacrificial capping layer is introduced as an intermediary between the plasma etch process and the underlying source/drain region. This layer absorbs the harmful effects of ion bombardment while allowing the etch to proceed efficiently through the etch stop layer, protecting the underlying material from damage
Solution Approach 2:
The sacrificial capping layer is designed as a temporary, disposable protective layer that is intentionally formed and then removed after serving its protective function. This layer sacrifices itself to protect the valuable underlying source/drain region during the etching process
2Speed
If a plasma etch process is used, then etching speed is improved, but ion bombardment damage increases
Solution Approach 1:
The sacrificial capping layer acts as a mediator that allows the plasma etch process to maintain its high speed while protecting the underlying material from ion bombardment damage. The layer absorbs the ion bombardment while the etch proceeds rapidly through the etch stop layer
3Reliability
If a sacrificial capping layer is formed during plasma etching, then protection of source/drain region is improved, but process complexity increases
Solution Approach 1:
The formation of the sacrificial capping layer is merged with the existing plasma etch process for removing the etch stop layer. The same plasma process that etches the etch stop layer also forms the sacrificial capping layer on the exposed source/drain region, combining two functions into one step
Solution Approach 2:
The plasma etch process itself provides the protective function by forming the sacrificial capping layer during the etching of the etch stop layer. The process serves dual purposes: removing the etch stop layer and protecting the underlying source/drain region
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
The sacrificial oxide capping layer effectively prevents damage to semiconductor regions during plasma etching, maintaining the integrity of the epitaxial source/drain materials and ensuring high etch selectivity, thus improving device performance and yield.
Implementation Method 1
A plasma etching process is performed using an etching gas that removes the etch stop layer and forms a sacrificial oxide capping layer on the source/drain region
Implementation Method 2
the plasma etch process possesses a plasma source that generates a sea of ions that accelerate in a manner that causes ion bombardment against sensitive device layers
Implementation Method 3
forms a sacrificial oxide capping layer on the source/drain region
Data Source
AI summary
A method which includes providing a substrate having a source/drain region and an etch stop layer on the source/drain region. A plasma etching process is performed using an etching gas that removes the etch stop layer and forms a sacrificial oxide capping layer on the source/drain region. The sacrificial oxide capping layer is then from the source/drain region.