Transistor Array Pitch-Specific Etching for Uniform Spacer Thickness
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Solution Overview
Problem
The variation in pattern density and pitch between different types of devices on a semiconductor chip leads to disparities in film thickness and chemical reactant balance, affecting device performance.
Innovation Solution
Applying different treatments to narrow and wide pitch arrays by using masks to selectively expose devices to etching processes, adjusting the proximity of semi-circular profiles to polysilicon structures, and employing dummy polysilicon structures to tune deposition rates of sidewall spacers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If different pitch arrays are processed with uniform etching conditions, then manufacturing simplicity is maintained, but film thickness disparities and chemical reactant balance issues occur affecting device performance
Solution Approach 1:
The patent applies different etching conditions to different pitch arrays by introducing pitch-specific parameters (etch power, pressure, gas flow rates) tailored to each array's pitch characteristics. This local customization ensures that narrow pitch and wide pitch arrays receive optimized etching treatment, resolving the film thickness consistency issue while maintaining manufacturing feasibility through automated parameter selection.
2Manufacturing precision
If multiple etching processes are applied to different pitch arrays, then etching precision is improved, but process complexity increases
Solution Approach 1:
The patent implements dynamic process adaptation by automatically selecting and adjusting etching parameters based on the detected pitch of each array. The system dynamically modifies etch power, pressure, and gas flow rates during processing, enabling precise control for different pitch arrays without requiring manual intervention or complex multi-step processes. This dynamic approach simplifies the overall process while maintaining high precision.
3Ease of manufacture
If sidewall spacer deposition is performed without pitch-based optimization, then process simplicity is maintained, but spacer thickness uniformity deteriorates
Solution Approach 1:
The patent optimizes sidewall spacer deposition by adjusting deposition parameters (temperature, pressure, deposition rate) based on the pitch characteristics of each array. This parameter customization ensures uniform spacer thickness across different pitch arrays, resolving the thickness uniformity issue while maintaining process simplicity through automated parameter selection based on pitch detection.
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 consistent performance across devices with varying pitches by optimizing the undercut etch process and sidewall spacer deposition, thereby improving device performance.
Implementation Method 1
etching the semiconductor substrate using a first etch process
Implementation Method 2
employing dummy polysilicon structures to tune deposition rates of sidewall spacers
Data Source
AI summary
The present disclosure describes a method for fabricating semiconductor structures having transistor arrays with different pitches. The method can include forming a first and second arrays of structures on a semiconductor substrate. The second array of structures can be blocked with a first mask while exposing the first array. A first treatment can be applied to the first array of structures. The first array of structures can be blocked with a second mask while exposing the second array of structures. A second treatment can be applied to the second array of structures, where the second treatment is different from the first treatment.