FinFET Recess Formation Using Single Photomask and Differential Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor processes for forming fin field effect transistors (Fin FETs) face challenges in achieving uniform element density and precise feature sizes, requiring multiple photomasks and separate etching processes for different regions, which increases complexity and reduces efficiency as transistor sizes shrink.
Innovation Solution
A method is developed where a substrate is divided into dense and isolation regions, with a first dielectric layer formed and recesses created, followed by a second dielectric layer that fills these recesses, allowing for differential etching back processes to maintain pattern integrity in the isolation region using a single photomask, reducing the number of photomask uses and enhancing process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate etching processes with different photomasks are used for dense regions and isolation regions, then uniform element density and precise feature sizes can be achieved, but the number of photomasks increases and process complexity increases
Solution Approach 1:
The substrate is divided into dense regions and isolation regions with different element densities. Recesses are selectively formed in different regions with different dimensions - multiple smaller recesses in dense regions and fewer larger recesses in isolation regions. This segmentation allows each region to be optimized independently while using a single photomask pattern.
Solution Approach 2:
Different regions are given different local properties through selective recess formation. The dense regions receive multiple small recesses to maintain high element density, while isolation regions receive fewer large recesses to maintain spacing. This local differentiation achieves region-specific optimization without requiring separate photomasks.
2Manufacturing precision
If multiple photomasks are used for different regions, then uniform element density can be maintained, but the number of photomask usage times increases and process efficiency decreases
Solution Approach 1:
A single photomask pattern serves multiple functions by defining recess locations for both dense regions and isolation regions simultaneously. The same photomask pattern is used to create the initial recess structure across the entire substrate, eliminating the need for separate photomasks for different regions and improving process efficiency.
Solution Approach 2:
The photomask pattern is applied in advance to define all recess locations across the substrate before any selective processing. This preliminary patterning establishes the framework for subsequent selective recess formation, allowing efficient processing of both dense and isolation regions with a single mask application.
3Productivity
If a single photomask is used for both dense and isolation regions, then photomask usage times are reduced and process efficiency improves, but achieving uniform element density and precise features becomes more difficult
Solution Approach 1:
The recess formation process is made dynamic and adaptive to local conditions. After the single photomask defines all recess locations, subsequent processing steps selectively modify recess characteristics based on regional requirements - dense regions receive multiple etching cycles to create smaller recesses, while isolation regions receive different processing to create larger recesses with proper spacing.
Solution Approach 2:
Processing parameters are changed according to region type after the single photomask application. Etching depth, etching time, and other parameters are adjusted to transform the uniformly patterned recesses into region-specific structures - smaller recesses in dense regions and larger recesses in isolation regions - thereby achieving precise element density control with a single mask.
Data Source
AI summary
The present invention provides a method of fabricating a semiconductor structure. Firstly, a substrate is provided, a dense region and an isolation region are defined, next, a first dielectric layer is formed on the dense region and the isolation region, and then a plurality of first recesses are formed in the first dielectric layer within the dense region, and a second recess is formed in the first dielectric layer within the isolation region, wherein the width of the second recess is greater than three times of the width of each first recess. Afterwards, a second dielectric layer is then filled in each first recess and the second recess, wherein a top surface of the second dielectric layer within the isolation region is higher than a top surface of the second dielectric layer within the dense region. Next, an etching back process is performed, to remove the second dielectric layer.