Composite Etch Mask Structure for High-Aspect-Ratio Patterning
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Solution Overview
Problem
In semiconductor device manufacturing, there is a need for a technology that provides high etch resistance and maintains the shape of patterns with high aspect ratios, such as holes or grooves, during the etching process, as existing mask patterns are exposed to etching gases for extended periods and face challenges in retaining their shape.
Innovation Solution
A pattern forming method involving the formation of a carbon-based first film and a metal-containing second film, where the second film is infiltrated with metal, providing enhanced etch resistance and selectivity during the etching process, allowing for the maintenance of high aspect ratio patterns by using specific etching gases that do not react with the metal-containing film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional mask pattern is used for etching high aspect ratio patterns, then the etching process can be completed, but the mask pattern loses its shape and etch resistance during prolonged exposure to etching gas
Solution Approach 1:
The patent applies composite materials by forming a multi-layer mask structure consisting of a first film (carbon-based material) and a second film (metal-containing material). This composite structure combines the advantages of both materials: the carbon-based first film provides good etch resistance, while the metal-containing second film enhances structural stability and shape maintenance during prolonged etching exposure. The synergistic effect of these composite materials resolves the contradiction between maintaining etch resistance and withstanding long-term gas exposure.
Solution Approach 2:
The patent changes the material parameters of the mask by selecting specific materials with appropriate properties. The first film uses carbon-based materials (such as amorphous carbon or diamond-like carbon) with high etch resistance, while the second film uses metal-containing materials (such as aluminum, titanium, or tungsten) with high thermal and structural stability. These parameter changes in material selection enable the mask to maintain both etch resistance and shape integrity during extended exposure to etching gas.
2Productivity
If the mask etching rate is increased to complete the process faster, then productivity improves, but the mask shape deteriorates due to reduced etch resistance
Solution Approach 1:
The composite mask structure enables differential etching rates between the mask layers and the underlying film. The first film (carbon-based) and second film (metal-containing) are designed with different etching rates relative to the target film, allowing the etching process to proceed at an optimized speed while the composite structure itself maintains its shape. This resolves the contradiction between productivity and precision by enabling faster etching without mask degradation.
Solution Approach 2:
The patent applies local quality by creating a mask structure where different regions (layers) have different material properties and etching rates. The first film and second film are positioned at different locations in the mask stack, each contributing different local properties: the carbon-based first film provides surface etch resistance, while the metal-containing second film provides structural support. This local differentiation allows the overall mask to maintain shape accuracy while enabling higher productivity.
3Device complexity
If a single-layer mask is used, then the process is simpler, but the selectivity between mask and target film is insufficient
Solution Approach 1:
The patent uses composite materials to achieve high etching selectivity without excessive complexity. The two-layer structure (carbon-based first film + metal-containing second film) provides sufficient material property differentiation to ensure that the mask etches at a different rate than the target film, achieving the required selectivity. This relatively simple composite structure avoids the need for more complex multi-layer or tapered mask designs while still providing the necessary manufacturing precision.
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 effectively decreases the etching rate of the mask while maintaining the etching rate of the semiconductor target film, ensuring high selectivity and preserving the shape of high aspect ratio patterns throughout the etching process, thereby improving manufacturing yield and productivity.
Implementation Method 1
forming a second film containing metal and carbon and different from the first film, on a second region of the processing target film
Data Source
AI summary
A pattern forming method includes: forming a first film on a first region of a processing target film; forming a second film containing metal and carbon and different from the first film, on a second region of the processing target film; etching the first film; and etching the processing target film using the first film after the etching while the second film is exposed.