Tin Oxide Mandrels for Precise Sidewall Spacer Patterning
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges in achieving precise control over spacer and mandrel geometry, as well as high efficiency, particularly in the use of spacers formed on semiconductor substrates.
Innovation Solution
The use of tin oxide films as mandrels in semiconductor processing, where a method involves forming a layer of spacer material on tin oxide protruding features, selectively removing the spacer material from horizontal surfaces to expose underlying tin oxide, and subsequently removing the tin oxide protruding features while preserving the spacer material at the sidewalls, thereby forming spacers over an etch stop layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional spacer formation methods are used, then spacers can be formed on semiconductor substrates, but precise control over spacer and mandrel geometry is difficult to achieve
Solution Approach 1:
The patterning process is divided into multiple sequential steps: forming mandrels, depositing spacer material, selectively removing spacer from horizontal surfaces, removing mandrels, and selectively removing remaining spacer from sidewalls. This segmentation allows independent optimization of each step to achieve precise geometry control
Solution Approach 2:
The spacer material is deposited conformally on mandrels before mandrel removal, creating a preliminary structure that defines the final spacer geometry. The selective removal of spacer from horizontal surfaces also occurs before mandrel removal, preparing the structure for precise final formation
2Manufacturing precision
If multiple patterning steps are performed to achieve precise geometry, then spacer and mandrel control improves, but processing time and efficiency decrease
Solution Approach 1:
The conformal deposition of spacer material automatically follows the mandrel geometry, and the selective etching processes automatically remove material from specific surfaces based on their orientation. This self-service mechanism reduces the need for additional control steps while maintaining precision
Solution Approach 2:
Different etching parameters and chemistries are used for different selective removal steps: fluorine-based chemistry for silicon-containing spacer removal, chlorine-based chemistry for titanium dioxide spacer removal, and hydrogen-based chemistry for tin oxide mandrel removal. These parameter changes enable precise control while optimizing each step for speed
3Manufacturing precision
If selective etching is used to remove mandrels while preserving sidewall spacers, then precise spacer formation is achieved, but process complexity increases
Solution Approach 1:
The spacer material acts as an intermediary that protects underlying structures during mandrel removal. The selective etching of mandrels is enabled by the presence of this intermediary layer, which can be selectively removed afterward to complete the spacer formation
Solution Approach 2:
Mechanical or chemical etching processes are used instead of physical removal methods to selectively remove mandrels and spacer material. The etching chemistry provides selective removal based on material composition rather than mechanical properties
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 high-level control over spacer and mandrel geometry, achieving high efficiency in semiconductor substrate processing, and enabling integration with various materials and etching processes.
Implementation Method 1
removing the spacer material from horizontal surfaces in (c) comprises etching the spacer material using fluorine-based etch chemistry
Implementation Method 2
removing the spacer material from horizontal surfaces in (c) comprises etching the spacer material using chlorine-based etch chemistry
Implementation Method 3
removing the tin oxide protruding features comprises contacting the semiconductor substrate with a plasma-activated hydrogen-containing reactant selected from the group consisting of H2, HBr, NH3, H2O, a hydrocarbon, and combinations thereof
Implementation Method 4
a hydrogen-based etch chemistry that results in a formation of a tin hydride
Data Source
AI summary
Tin oxide films are used as mandrels in semiconductor device manufacturing. In one implementation the process starts by patterning a tin oxide layer using at least one of a hydrogen-based etch chemistry and a chlorine-based etch chemistry, and using patterned photoresist as a mask, thereby providing a substrate having a plurality of protruding tin oxide features (mandrels). Next, a conformal layer of spacer material is formed both on the horizontal surfaces and on the sidewalls of the mandrels. The spacer material is then removed from the horizontal surfaces exposing the tin oxide material of the mandrels, without fully removing the spacer material residing at the sidewalls of the mandrels. Next, mandrels are selectively removed (e.g., using hydrogen-based etch chemistry), while leaving the spacer material that resided at the sidewalls of the mandrels. The resulting spacers can be used for patterning underlying layers on the substrate.