Dual-Layer Etch Stop Structure for Semiconductor Plug Formation
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Solution Overview
Problem
In semiconductor manufacturing, the formation of conductive plugs can be compromised by misalignment of masks during etching, leading to incomplete contact with conductive structures or short circuits due to the inability of existing etch stop layers to withstand the etching process effectively, especially when removing adhesive layers.
Innovation Solution
The implementation of a dual-layer etch stop structure comprising a first doped etch stop layer and a second etch stop layer with specific material compositions and thicknesses, where the first etch stop layer is capable of withstanding the etching process for removing the adhesive layer, and the second etch stop layer is selectively etched to form openings for conductive plugs, enhancing manufacturing tolerance and preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single etch stop layer is used, then the structure is simple, but it cannot withstand the etching process effectively leading to misalignment and short circuits
Solution Approach 1:
The single etch stop layer is divided into two distinct layers: a first etch stop layer (silicon oxide) and a second etch stop layer (silicon nitride). Each layer serves a specific function - the first layer withstands the adhesive layer etching while the second layer provides selective etching for contact plug formation, thereby improving reliability without excessive complexity
Solution Approach 2:
The etch stop structure uses composite materials with different etch resistances and selective properties. The combination of silicon oxide and silicon nitride creates a multi-functional etch stop system where each material contributes its unique properties to solve the etching challenges
2Ease of manufacture
If mask alignment is relaxed for easier manufacturing, then manufacturing tolerance broadens, but contact precision between conductive plugs and structures deteriorates
Solution Approach 1:
The dual-layer etch stop structure acts as an intermediary buffer zone that compensates for mask alignment variations. The first etch stop layer provides a robust barrier that can absorb alignment errors during adhesive removal, while the second layer enables precise contact plug formation, thus decoupling manufacturing ease from precision requirements
Solution Approach 2:
The etch stop layers are positioned beforehand to create a protective buffer that cushions against potential misalignment. This pre-positioned buffer allows for broader manufacturing tolerances while maintaining precise contact through the selective etching capability of the second etch stop layer
3Productivity
If adhesive layer removal is performed aggressively to improve productivity, then manufacturing time decreases, but short circuits occur due to insufficient etch stop layer protection
Solution Approach 1:
The first etch stop layer is formed in advance before adhesive layer removal to establish a protective barrier. This preliminary action ensures that even aggressive etching processes cannot penetrate through to cause short circuits, allowing high-speed adhesive removal while maintaining reliability
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 dual-layer etch stop structure improves the reliability of conductive plug formation by broadening manufacturing tolerance and preventing short circuits, ensuring accurate contact between conductive plugs and structures while maintaining process selectivity.
Implementation Method 1
the first etch stop layer is capable of withstanding the etching process for removing the adhesive layer
Implementation Method 2
the second etch stop layer is selectively etched to form openings for conductive plugs
Data Source
AI summary
A semiconductor structure includes a substrate, a conductive feature over the substrate, a conductive plug structure contacting a portion of an upper surface of the conductive feature, a first etch stop layer over another portion of the upper surface of the conductive feature, and a second etch stop layer over the first etch stop layer. The first etch stop layer is a doped etch stop layer. The first etch stop layer is to function as an etch stop layer during a predetermined etching process for etching the second etch stop layer.