Selective Contact Formation Using Masking and Resist Patterning
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Solution Overview
Problem
In semiconductor device processing, the indiscriminate deposition of metal silicide or other contact materials onto exposed silicon regions can lead to electrical shorts and other undesirable effects, making it necessary to develop a method for selective formation of conductive contacts that avoids deposition in undesirable memory device regions.
Innovation Solution
The method involves depositing a resist over memory device components, selectively removing it to expose specific control gates and junctions, and then forming conductive contacts only on these exposed areas, while protecting other regions from metal deposition using a combination of dry and wet etching processes and thermal annealing to form metal silicides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal silicide or contact material is deposited indiscriminately onto exposed silicon regions, then complete coverage of all exposed surfaces is achieved, but electrical shorts and device performance degradation occur
Solution Approach 1:
The patent applies local quality by making different regions of the substrate have different properties through selective resist removal. Areas requiring contact material deposition are exposed by removing resist, while areas requiring protection retain their resist coating. This enables the same deposited material to have different functional outcomes in different locations - forming conductive contacts where needed and being prevented from forming shorts where not needed.
Solution Approach 2:
The resist layer serves as an intermediary protective layer that controls where metal silicide or contact material can be deposited. By selectively removing the resist in certain areas while maintaining it in others, the process mediates between the need for complete coverage and the need to prevent harmful deposition, allowing the deposited material to only form in desired locations.
2Ease of manufacture
If resist is completely removed to expose all components for uniform processing, then processing simplicity is improved, but selective contact formation becomes impossible
Solution Approach 1:
The patent makes different parts of the resist layer have different fates - some areas are removed while others are retained. This local differentiation allows the same simple blanket deposition process to achieve selective contact formation, combining processing simplicity with manufacturing precision by making the selectivity inherent in the resist pattern rather than in the deposition process itself.
3Manufacturing precision
If selective resist removal is performed to enable precise contact formation, then manufacturing precision is improved, but process complexity increases
Solution Approach 1:
The patent performs preliminary action by depositing the resist layer and selectively removing it before the metal silicide or contact material deposition step. This preliminary preparation of the surface topology - creating exposed areas and protected areas - enables the subsequent simple blanket deposition to achieve the complex selective contact formation goal without requiring complex deposition equipment or multiple deposition steps.
Solution Approach 2:
The resist layer acts as an intermediary that simplifies the overall process. Instead of requiring complex selective deposition techniques, the resist intermediary transforms the problem into a simple blanket deposition onto a pre-patterned surface, where the selectivity is determined by the resist pattern rather than by complex deposition control.
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 allows for the selective formation of metal silicide contacts on active elements of memory devices, preventing unwanted deposition and ensuring reliable interconnections without compromising device performance by avoiding electrical shorts or other operational failures.
Implementation Method 1
The resist is etched to thereby expose each of the first component control gates, but not the substrate surrounding the first component control gates
Implementation Method 2
thermal annealing to form metal silicides
Implementation Method 3
depositing metal silicide or other contact material onto the exposed silicon 44
Data Source
AI summary
A method for manufacturing a semiconductor device including selective conductive contacts includes the step of depositing a resist over first and second memory device components, each of the first and second components comprising junctions formed in the substrate and a gate formed on the substrate between the junctions. The resist is then removed from the second components to thereby form a resist opening above each of the second component control gates and junctions. The resist is then etched to thereby expose each of the first component control gates but not the substrate surrounding the first component control gates. Conductive contacts are then formed on the exposed first component control gates, and the second component control gates and junctions.