Etch Stop Sidewall Protection for Contact Shorts
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Solution Overview
Problem
In advanced semiconductor devices, the conventional contact plug manufacturing process leads to yield losses due to the formation of shorts and contact extensions between neighboring contacts and adjacent gate electrodes, particularly in densely packed transistor regions, as the feature sizes shrink and the distance between contacts decreases.
Innovation Solution
A protection layer is formed on the sidewalls of the etch stop layer by re-depositing material from the contact region using a sputter process, preventing cavity formation during wet chemical cleaning and reducing the risk of shorts during the contact plug fill process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If contact plugs are formed with reduced feature sizes to increase packing density, then the number of circuit elements per chip area increases, but the risk of shorts and contact extensions between neighboring contacts increases
Solution Approach 1:
The patent applies preliminary action by forming the protection layer on the sidewalls of the etch stop layer before performing the wet chemical cleaning step. This pre-formed layer prevents cavity formation during cleaning, which in turn prevents shorts during the subsequent contact plug fill process. The protection layer is deposited in advance to counteract the harmful effect of cavity formation that would otherwise occur during the cleaning step.
Solution Approach 2:
The protection layer acts as an intermediary between the etch stop layer and the wet chemical cleaning process. It mediates the interaction by providing a protective barrier that prevents the cleaning chemistry from attacking the etch stop layer sidewalls, thereby preventing cavity formation without interfering with the necessary cleaning function.
2Ease of manufacture
If wet chemical cleaning is performed to clean contact openings, then cleaning effectiveness is achieved, but cavity formation occurs in the etch stop layer
Solution Approach 1:
The protection layer is formed in advance before the wet chemical cleaning step, creating a protective barrier that prevents cavity formation during cleaning. This preliminary action allows the cleaning process to proceed effectively while protecting the etch stop layer from damage.
Solution Approach 2:
The protection layer serves as an intermediary that protects the etch stop layer during the wet chemical cleaning process. It allows the cleaning chemistry to access and clean the contact opening surfaces while preventing the chemistry from attacking the etch stop layer sidewalls, thus maintaining etch stop layer integrity.
3Length of moving object
If contact plugs are formed with high aspect ratios due to feature size shrinkage, then smaller feature sizes are achieved, but sophisticated etch and deposition techniques are required
Solution Approach 1:
The protection layer is formed in advance before the contact plug fill process, providing a protective barrier that simplifies the subsequent filling operation. By pre-forming this layer, the patent reduces the complexity of the overall process, as the protection layer prevents cavity formation that would otherwise require additional corrective steps.
Solution Approach 2:
The protection layer acts as an intermediary structure that facilitates the formation of high aspect ratio contact plugs by preventing cavity formation during cleaning. This intermediary layer simplifies the deposition process by ensuring a uniform surface for subsequent material filling, reducing the sophistication required for the deposition technique.
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 significantly reduces the formation of shorts and improves the reliability of semiconductor devices by maintaining the integrity of the etch stop layer and ensuring accurate contact formation without affecting the wet chemical cleaning step or the etch stop layer process.
Implementation Method 1
A protection layer is formed on the sidewalls of the etch stop layer by re-depositing material from the contact region using a sputter process
Data Source
AI summary
A semiconductor device includes a silicide contact region positioned at least partially in a semiconductor layer, an etch stop layer positioned above the semiconductor layer, and a dielectric layer positioned above the etch stop layer. A contact structure that includes a conductive contact material extends through at least a portion of the dielectric layer and through an entirety of the etch stop layer to the silicide contact region, and a silicide protection layer is positioned between sidewalls of the etch stop layer and sidewalls of the contact structure.