Photomask Layout With Ring Pattern to Prevent Spacer Residues
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Solution Overview
Problem
The self-aligned double patterning (SADP) process in semiconductor manufacturing often results in spacer residues, leading to defects and requiring additional etching processes to remove them, which increases manufacturing costs and can reduce film layer heights.
Innovation Solution
A photomask structure with alternately arranged first and second layout patterns and a ring-shaped layout pattern is used, allowing for the prevention of spacer residues during the patterning process, eliminating the need for etching to remove these residues and improving process window efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If SADP process is used to reduce line width and improve pattern transfer accuracy, then manufacturing precision is improved, but spacer residues are generated leading to defects
Solution Approach 1:
The photomask pattern is segmented into first and second layout patterns with alternating arrangement, where the first layout patterns have ends connected to the ring-shaped layout pattern and the second layout patterns have ends not connected. This segmentation creates asymmetric spacer formation that prevents residue generation while maintaining pattern transfer accuracy.
Solution Approach 2:
The invention introduces asymmetric design in the photomask pattern by having first layout patterns with ends connected to the ring-shaped layout pattern and second layout patterns with ends not connected. This asymmetry causes spacers to form differently on different sides, enabling complete spacer removal without residues while maintaining the self-aligned double patterning precision.
2Reliability
If etching process is performed to remove spacer residues, then defect rate is reduced, but manufacturing cost increases and film layer height is reduced
Solution Approach 1:
The photomask pattern is designed in advance with asymmetric connectivity to the ring-shaped layout pattern, which preliminarily prevents spacer residue formation during the spacer formation process. This preliminary design eliminates the need for subsequent etching processes to remove residues, reducing manufacturing costs and preserving film layer heights.
3Reliability
If etching process is performed to remove spacer residues, then defect rate is reduced, but process window is narrowed
Solution Approach 1:
The asymmetric photomask pattern design preliminarily prevents spacer residue formation, eliminating the need for additional etching processes. This maintains a wider process window by reducing the number of process steps and minimizing cumulative process variations, thereby improving overall productivity while maintaining low defect rates.
Data Source
AI summary
A photomask structure includes a plurality of first layout patterns, a plurality of second layout patterns, and a ring-shaped layout pattern. The first layout patterns and the second layout patterns are alternately arranged. Each of the first layout patterns has a first end and a second end. Each of the second layout patterns has a third end and a fourth end. The first end is adjacent to the third end. The second end is adjacent to the fourth end. The ring-shaped layout pattern surrounds the first layout patterns and the second layout patterns. The first end is connected to the ring-shaped layout pattern. The second end is not connected to the ring-shaped layout pattern. The third end is not connected to the ring-shaped layout pattern. The fourth end is connected to the ring-shaped layout pattern.