Partial Silicide Contact Formation Without a Silicide Block Mask
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Solution Overview
Problem
Conventional methods for forming partially silicided elements in IC devices require an additional photomask process, increasing manufacturing costs, and there is a need for improved methods that eliminate the use of silicide block layers.
Innovation Solution
A method is provided to form partially silicided elements by forming a silicided structure, depositing a dielectric region, creating contact and tub openings, and using a conformal metal to define conductive contacts while selectively removing the silicide layer in specific areas without the need for a silicide block layer, thereby reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a silicide block layer is used to form partially silicided elements, then selective silicidation is achieved, but manufacturing cost increases due to additional photomask process
Solution Approach 1:
The patent applies preliminary action by forming the silicide layer on the entire base structure surface before selective removal. Instead of preventing silicidation in certain areas (block layer approach), the method first silicides all areas uniformly, then selectively removes silicide from regions where non-silicided surfaces are needed. This preliminary full silicidation followed by selective removal eliminates the need for photomask-aligned block layers.
Solution Approach 2:
The patent inverts the conventional approach by reversing the sequence of silicidation and blocking operations. Rather than blocking silicide formation in specific areas during the silicidation process, the method forms silicide everywhere first, then removes it selectively from areas requiring non-silicided surfaces. This inversion of the process sequence eliminates the need for complex photomask alignment.
2Manufacturing precision
If a silicide block layer is used to form partially silicided elements, then selective silicidation is achieved, but process complexity increases
Solution Approach 1:
The patent applies the extraction principle by removing the silicide block layer from the process entirely. Instead of adding a blocking layer that requires photomask alignment and subsequent removal, the method extracts this intermediate blocking structure and replaces it with a simpler selective removal process applied to a pre-formed silicide layer.
Solution Approach 2:
The patent applies discarding and recovering by selectively removing silicide from specific regions after uniform formation. The silicide is formed across the entire surface, then discarded (removed) from areas where non-silicided surfaces are needed, while being retained in areas requiring low contact resistance. This approach discards the complex block layer process in favor of selective removal.
3Manufacturing precision
If conventional silicide blocking process is used, then partially silicided elements are formed, but additional photomask process is required
Solution Approach 1:
The patent applies merging by combining the silicide formation and patterning steps into a single process sequence. Instead of using a photomask to define blocked regions during silicidation, the method forms the silicide layer uniformly and then uses a subsequent etch process to define the final silicided regions. This merges what were previously separate photomask-aligned operations into a streamlined sequence.
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 method allows for the concurrent formation of partially and fully silicided elements in IC devices without additional mask layers, thereby reducing manufacturing costs and improving efficiency.
Implementation Method 1
A silicided element includes a metal silicide layer formed on a base structure, e.g., a polysilicon element or an active region, wherein the silicide layer exhibits increased conductance
Implementation Method 2
A conformal metal is deposited over the dielectric region, the deposited conformal metal (a) filling the contact opening to define a contact conductively connected to the first area of the silicide layer
Data Source
AI summary
A method of forming a partially silicided element is provided. A silicided structure including a silicide layer on a base structure is formed. A dielectric region is formed over the silicided structure. The dielectric region is etched to form a contact opening exposing a first area of the silicide layer and a tub opening exposing a second area of the silicide layer. A conformal metal is deposited to (a) fill the contact opening to define a contact and (b) form a cup-shaped metal structure in the tub opening. Another etch is performed to remove the cup-shaped metal structure in the tub opening, to remove the underlying silicide layer second area and to expose an underlying area of the base structure, wherein the silicide layer first area remains intact. The base structure with the intact silicide layer first area and removed silicide layer second area defines the partially silicided element.