Curved Mask Corner for Uniform Etching
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Solution Overview
Problem
Conventional self-alignment double patterning (SADP) processes for semiconductor manufacturing often leave residues of the hard mask layer on the substrate, especially near corner portions, due to uneven etching, which prevents the precise formation of minute patterns.
Innovation Solution
A method involving the formation of a first mask with a curved inner side wall corner portion, a sacrificial layer, and a hard mask layer, where the hard mask layer is partially removed using an isotropic etching process until the sacrificial layer adjacent to the corner is exposed, allowing for the formation of a second mask pattern without residues, and using materials like polysilicon for the masks and metal oxide for the sacrificial layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional SADP process is used to form double mask pattern, then minute pattern formation is enabled, but hard mask layer residues remain on substrate especially near corner portions
Solution Approach 1:
The corner portion of the first mask pattern is designed with a curved inner side wall instead of a sharp corner. This curvature ensures uniform etching of the hard mask layer across the entire mask pattern, preventing the formation of residues near corner portions while maintaining the ability to form minute patterns through the SADP process
2Productivity
If hard mask layer is partially etched to form second mask pattern, then double mask pattern is formed, but uneven etching occurs adjacent to corner portions
Solution Approach 1:
By curving the inner side wall of the corner portion in the first mask pattern, the etching process achieves uniform removal of the hard mask layer across all regions. The curved geometry eliminates the uneven etching that would otherwise occur at sharp corners, ensuring consistent etching depth and maintaining manufacturing precision while preserving productivity
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 ensures that the hard mask layer residues are minimized near corner portions, maintaining uniform etching across the mask patterns, preventing defects and enabling the formation of finer structures on the substrate.
Implementation Method 1
The hard mask layer is partially removed until the sacrificial layer adjacent to the corner portion is exposed. Then, the sacrificial layer is removed so that a second mask pattern is formed
Implementation Method 2
the hard mask layer is partially removed by an isotropic etching process
Implementation Method 3
the sacrificial layer may be formed by an atomic layer deposition process
Data Source
AI summary
In the method of forming a mask structure, a first mask is formed on a substrate where the first mask includes a first mask pattern having a plurality of mask pattern portions having openings therebetween and a second mask pattern having a corner portion of which an inner side wall that is curved. A sacrificial layer is formed on the first mask. A hard mask layer is formed on the sacrificial layer. After the hard mask layer is partially removed until the sacrificial layer adjacent to the corner portion is exposed, a second mask is formed from the hard mask layer remaining in the space after removing the sacrificial layer. A minute pattern having a fine structure may be easily formed on the substrate.