Shallow Trench Isolation Conversion for Uniform FinFET Etch Rates
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving uniform conversion and composition of dielectric layers between fins of varying widths, leading to non-uniform etching and electrical performance issues in FinFET manufacturing.
Innovation Solution
The process involves forming fins with specific height and width ratios in different regions, followed by a conversion process using a silicon-containing and nitrogen-containing precursor mixture, and a subsequent anneal in an oxygen-containing ambient to achieve a uniform second dielectric layer with controlled thickness and composition, ensuring uniform etch rates and electrical performance across regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional dielectric layer conversion process is used, then the process is simple, but the conversion is non-uniform between fins of varying widths leading to poor manufacturing precision
Solution Approach 1:
The conversion process is divided into multiple sequential conversion steps, where each step converts a portion of the first dielectric layer to the second dielectric layer. This segmentation allows control over the conversion uniformity by adjusting the number of steps and the conditions of each step, thereby achieving uniform conversion across fins of varying widths while managing process complexity.
Solution Approach 2:
The method performs preliminary actions by controlling the conversion process to achieve uniform thickness of the second dielectric layer before subsequent etching operations. This preliminary control of dielectric layer uniformity ensures that etch rates are consistent across different fin regions, improving manufacturing precision in downstream processes.
2Productivity
If fins of different widths are formed in different regions, then integration density is improved, but etch rate uniformity deteriorates
Solution Approach 1:
The method applies local quality by forming fins of different widths in different regions to optimize integration density, while simultaneously applying a uniform conversion process across all regions that ensures consistent dielectric layer properties. This allows each region to have optimized fin dimensions while maintaining uniform etch characteristics across the entire substrate.
Solution Approach 2:
The invention changes the parameters of the dielectric layer conversion process, specifically controlling the conversion conditions to achieve uniform thickness and composition of the second dielectric layer regardless of the underlying fin width variations. This parameter control decouples the etch rate from the fin width, allowing high integration density without sacrificing etch uniformity.
3Loss of time
If the first dielectric layer is converted completely in one step, then the process time is reduced, but the composition uniformity deteriorates
Solution Approach 1:
The conversion process is implemented as periodic action through multiple conversion steps, where each step partially converts the first dielectric layer. By repeating the conversion process in controlled intervals, the method achieves uniform composition throughout the second dielectric layer while managing the total process time through efficient step design and optimization.
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 results in a more uniform quality and composition of the second dielectric layer, enabling precise control of fin heights and etch rates, thereby improving the manufacturing yield and electrical performance of FinFETs.
Implementation Method 1
a conversion process using a silicon-containing and nitrogen-containing precursor mixture, and a subsequent anneal in an oxygen-containing ambient
Implementation Method 2
a subsequent anneal in an oxygen-containing ambient to achieve a uniform second dielectric layer with controlled thickness and composition
Data Source
AI summary
A method includes forming a first plurality of fins in a first region of a substrate, a first recess being interposed between adjacent fins in the first region of the substrate, the first recess having a first depth and a first width, forming a second plurality of fins in a second region of the substrate, a second recess being interposed between adjacent fins in the second region of the substrate, the second recess having a second depth and a second width, the second width of the second recess being less than the first width of the first recess, the second depth of the second recess being less than the first depth of the first recess, forming a first dielectric layer in the first recess and the second recess, and converting the first dielectric layer in the first recess and the second recess to a treated dielectric layer.