Bi-layer Etch Mask for Deep Carbonaceous Substrate Processing
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Solution Overview
Problem
Conventional etching methods face challenges with carbonaceous materials like diamond due to their chemical inertness and high thermal conductivity, leading to poor etch selectivity and thermal mismatch issues that result in mechanical failure of etch masks during deep etching processes.
Innovation Solution
A bi-layer etch mask comprising a first masking layer with low thermal expansion and high thermal conductivity, and a second masking layer with high etch selectivity, is used to achieve stable deep etching of carbonaceous substrates, allowing for efficient heat dissipation and minimizing thermal mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-layer etch mask is used on carbonaceous substrates, then the etching process can proceed, but thermal mismatch causes mechanical failure of the etch mask during deep etching
Solution Approach 1:
The patent applies composite materials by creating a bi-layer etch mask structure consisting of a first masking layer (e.g., chromium) and a second masking layer (e.g., nickel). The first layer has low thermal expansion coefficient matching the carbonaceous substrate, while the second layer provides high etch selectivity. This composite structure resolves the thermal mismatch problem by combining materials with complementary properties, preventing mechanical failure during deep etching processes.
Solution Approach 2:
The etch mask is segmented into two distinct functional layers: a first masking layer optimized for thermal compatibility with the substrate and a second masking layer optimized for etch selectivity. This segmentation allows each layer to independently perform its specific function without compromising the other, addressing both the thermal mismatch and etching performance requirements simultaneously.
2Length of moving object
If a thick etch mask is used to achieve deep etching, then deeper patterns can be formed, but the etch mask becomes more susceptible to mechanical failure due to thermal stress
Solution Approach 1:
The bi-layer composite structure enables deep etching by distributing thermal stress across two materials with different mechanical properties. The first layer's low thermal expansion coefficient reduces overall thermal stress accumulation, while the second layer maintains structural integrity during the etching process, allowing for deeper patterns without compromising mask strength.
3Manufacturing precision
If a etch mask with high etch selectivity is used, then precise etching is achieved, but thermal mismatch issues worsen leading to mask failure
Solution Approach 1:
The mask is segmented into two layers with distinct functions: the first layer (e.g., chromium) provides thermal compatibility with the carbonaceous substrate, while the second layer (e.g., nickel) provides high etch selectivity. This functional segmentation allows the system to achieve both precise etching and thermal stability, as each layer optimizes for its specific purpose without compromising the other.
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
The bi-layer etch mask enables stable deep etching of carbonaceous materials beyond several hundreds of micrometers with high aspect ratio patterns, achieving an etch selectivity ratio greater than 1:100 and preventing mechanical failure during the etching process.
Implementation Method 1
a first masking layer with low thermal expansion and high thermal conductivity... efficient heat dissipation
Implementation Method 2
low thermal expansion... minimizing thermal mismatch
Data Source
AI summary
A method comprising providing a carbonaceous material, the substrate having a first thermal conductivity. The method further comprises depositing a first masking layer having a second thermal conductivity on at least a portion of the substrate, a ratio of the second thermal conductivity to the first thermal conductivity being less than or equal to 1:30. The method further comprises depositing a second masking layer on the first masking layer to form an etch mask, and etching an exposed portion of the substrate.