Mask Blank Adhesion Layer Prevents Resist Collapse
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Solution Overview
Problem
The challenge in manufacturing semiconductor masks for DRAM half pitch of 65 nm or less is the insufficient adhesion of resist films, leading to pattern defects and loss of resist patterns during development, which affects the accuracy and resolution of the transfer mask.
Innovation Solution
A mask blank structure that includes a thin film and a resist film sandwiched by an adhesion layer, which prevents pattern collapse during development and enhances adhesion, using a resin film resistant to developers and optionally a silicon-containing or chromium-based thin film, with an intermediate layer for additional stability and patterning support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a high-resolution chemically amplified resist is used to achieve the semiconductor design rule (DRAM hp of 65 nm or less), then the resolution and pattern accuracy are improved, but the adhesion of the resist film becomes insufficient causing pattern loss during development
Solution Approach 1:
An adhesion layer is introduced between the thin film and the resist film to serve as an intermediary that enhances adhesion. The adhesion layer includes a first region and a second region with different compositions or structures, providing graded adhesion properties that prevent pattern loss during development while maintaining the high resolution enabled by the chemically amplified resist.
Solution Approach 2:
The adhesion layer is constructed as a composite structure with a first region and a second region having different material compositions. This composite configuration allows optimization of adhesion properties at the interface with the thin film while maintaining compatibility with the resist film, thereby preventing pattern collapse without compromising the resolution benefits of the chemically amplified resist.
2Manufacturing precision
If the linewidth of light-shielding patterns and phase shifters is reduced to achieve super-resolution (less than half of circuit pattern, e.g., linewidth of less than 100 nm), then the resolution of the transfer mask is improved, but the adhesion of the resist film becomes insufficient leading to pattern defects
Solution Approach 1:
The adhesion layer acts as a mediator between the thin film and the resist film, providing enhanced adhesion support that is particularly critical when forming ultra-fine patterns with linewidths of less than 100 nm. This intermediary structure prevents pattern loss during development, enabling the realization of super-resolution transfer masks with linewidths equal to or less than half of the circuit pattern size.
3Ease of manufacture
If reduction projection exposure is conducted through a transfer mask with simply enlarged circuit patterns, then the manufacturing process is simplified, but the transfer accuracy deteriorates due to interference of exposure light
Solution Approach 1:
The mask pattern is segmented into multiple functional regions: light-shielding patterns, phase shifters, and mask enhancers. This segmentation allows the mask to correct optical proximity effects and interfere with exposure light constructively, thereby achieving accurate pattern transfer. The adhesion layer with its multi-region structure supports the fabrication of these segmented features with precise dimensional control.
Solution Approach 2:
The transfer mask employs composite materials including light-shielding materials and phase shifter materials with different optical properties. This composite structure enables the mask to manipulate exposure light through phase shifting and interference, achieving accurate pattern transfer. The adhesion layer facilitates the precise formation of these composite structures by preventing pattern loss during the multi-step fabrication process.
Data Source
AI summary
To provide a mask blank which can eliminate pattern defects by preventing a resist pattern from disappearing at the time of manufacturing a transfer mask in semiconductor design rule (DRAM hp65 nm or below), and to provide a mask.A mask blank including a thin film for forming a mask pattern, the thin film being formed on a substrate, and a resist film formed over the thin film, wherein the thin film and the resist film sandwich an adhesion layer that is bonded to the thin film and the resist film, and the adhesion layer prevents, during development of the resist film in patterning of the resist film, collapse of the patterned resist film.