Semiconductor Isolation Film Etching for Step Difference Control
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Solution Overview
Problem
Conventional methods for forming semiconductor devices with varied isolation films on semiconductor substrates can lead to unexpected problems, such as step differences between isolation films and active regions, affecting product reliability.
Innovation Solution
A method involving the formation of hard mask patterns, oxide films, and different thicknesses of isolation films through dry cleaning and etching processes to ensure balanced etching of isolation films and prevent step differences, allowing for uniform metal gate formation and improved product reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional methods are used to form isolation films with modified shapes on semiconductor substrates, then device variety is achieved, but step differences occur between isolation films and active regions affecting product reliability
Solution Approach 1:
The patent divides the isolation film formation process into multiple stages: forming oxide films with different thicknesses in different regions, selectively etching first and second isolation films to different depths, and creating trenches at different levels. This segmentation allows each region to have optimized isolation film characteristics, achieving device variety while maintaining reliability by preventing step differences between isolation films and active regions.
2Adaptability or versatility
If isolation films are formed with different shapes and thicknesses, then device functionality is improved, but step differences create reliability issues
Solution Approach 1:
The patent applies local quality by forming oxide films with different thicknesses in different regions (first oxide film in first region, second oxide film in second region), and selectively etching isolation films to different depths. Each region has customized isolation film properties tailored to specific device requirements, while the overall process maintains manufacturing precision by controlling step differences through the multi-stage etching approach.
3Ease of manufacture
If uniform etching is applied to all isolation films, then process simplicity is maintained, but thickness variations cause step differences between isolation films and active regions
Solution Approach 1:
The patent employs preliminary action by forming oxide films with predetermined different thicknesses in different regions before the isolation film formation process. The first oxide film is formed thicker in the first region, and the second oxide film is formed thicker in the second region. This preliminary thickness differentiation enables subsequent selective etching to achieve uniform final isolation film thickness across different regions, preventing step differences while maintaining reasonable process complexity.
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 uniform etching of isolation films and active regions, enhancing the reliability and performance of semiconductor devices by preventing irregularities in metal gate thickness, thus maintaining intended transistor performance.
Implementation Method 1
forming an oxide film on the hard mask pattern and the first and second trenches
Implementation Method 2
forming an oxide film on the hard mask pattern and the first and second trenches
Implementation Method 3
etching the first isolation film by a first thickness by performing dry cleaning on the semiconductor substrate and etching the second isolation film to have a second thickness different from the first thickness
Data Source
AI summary
Provided are methods for fabricating a semiconductor device. The methods include forming a hard mask pattern on a semiconductor substrate, forming a first trench having a first width and a second trench having a second width on the semiconductor substrate using the hard mask pattern as a mask, forming an oxide film on the hard mask pattern and the first and second trenches, forming first and second isolation films on the first and second trenches by planarizing the oxide film until the hard mask pattern is exposed, and etching the first isolation film by a first thickness by performing dry cleaning on the semiconductor substrate and etching the second isolation film by a second thickness different from the first thickness.