Polysilicon Gate Etching Profile Control via Extension Step
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Solution Overview
Problem
In semiconductor manufacturing, the etching process for polysilicon gates results in non-uniform patterns due to variations in manufacturing conditions, leading to reduced reliability and production yield, as existing methods either damage the substrate excessively or fail to achieve desired profiles.
Innovation Solution
A patterning method that includes a main etching step, etching endpoint detection step, extension etching step, and over etching step, where the extension etching time is set within 10 seconds based on pre-layer information to achieve a required film profile, with etching rates and selectivities optimized to balance between steps, ensuring uniformity and minimizing substrate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the over etching time is extended to achieve desired gate profile, then the gate profile uniformity is improved, but the substrate is severely damaged and production yield is significantly reduced
Solution Approach 1:
The etching process is divided into multiple distinct steps: main etching step, etching endpoint detection step, extension etching step, and over etching step. Each step serves a specific function with optimized parameters, allowing precise control of gate profile while minimizing substrate damage and maintaining high production yield.
Solution Approach 2:
The etching endpoint detection step is performed before the extension etching step to identify when the main etching is complete. This preliminary detection allows subsequent steps to be optimized based on actual process conditions, preventing both over-etching damage and insufficient etching, thereby improving gate profile uniformity while maintaining productivity.
2Productivity
If the over etching time is reduced to maintain production yield, then production yield is maintained, but a foot-shaped profile is formed at the lower portion of the gate structure
Solution Approach 1:
The etching process is segmented into multiple steps with the extension etching step specifically designed to address profile uniformity. This step operates under optimized conditions to complete the etching process with precise control, eliminating foot-shaped profiles while maintaining short total etching time for high production yield.
Solution Approach 2:
Different etching parameters (time, power, gas flow ratios, pressure) are optimized for each etching step. The extension etching step uses specific parameter settings that differ from the main etching step, allowing precise control of the etching rate and profile development to achieve uniform gate structures without foot-shaped defects.
3Productivity
If different etching parameters are used for main etching and over etching steps, then etching rate and selectivity are optimized, but pattern uniformity across wafers is reduced due to manufacturing variations
Solution Approach 1:
The etching endpoint detection step provides real-time feedback on the etching process status. Based on this feedback, the extension etching step parameters are optimized to compensate for variations in manufacturing conditions, ensuring consistent gate profile and pattern uniformity across different wafers while maintaining high etching rates.
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
Effectively controls the profiles of patterns formed without significantly reducing production yield, improving etching uniformity and preventing substrate damage, while allowing for precise adjustment of gate structures.
Implementation Method 1
an etching process is performed to etch the film
Data Source
AI summary
A patterning method is provided. In the patterning method, a film is formed on a substrate and a pre-layer information is measured. Next, an etching process is performed to etch the film. The etching process includes a main etching step, an etching endpoint detection step, an extension etching step and an over etching step. An extension etching time for performing the extension etching step is set within 10 seconds based on a predetermined correlation between an extension etching time and the pre-layer information, so as to achieve a required film profile.