Litho-Etch-Litho-Etch Contact Hole Formation
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Solution Overview
Problem
The double exposure lithography process in semiconductor manufacturing faces challenges in maintaining accuracy and consistency due to the need for different manufacturing parameters in the first and second exposure development and etching processes, which affects the critical dimension of trench openings.
Innovation Solution
A method involving the formation of a thin etching stop layer on a target layer, followed by sequential lithography and etching processes to pattern the etching stop layer, allowing the same or similar manufacturing parameters to be used throughout, thereby maintaining the height of the photoresist layer and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a double exposure lithography process is used to manufacture finer patterns with higher density, then the pattern density and fineness are improved, but the manufacturing parameter consistency and critical dimension accuracy deteriorate
Solution Approach 1:
The patent segments the lithography process into two separate exposure steps with different parameter sets. The first exposure uses a first set of manufacturing parameters to form initial patterns, while the second exposure uses a second set of parameters to form additional patterns. This segmentation allows each exposure to be optimized independently, resolving the contradiction between achieving high pattern density and maintaining parameter consistency.
2Quantity of substance
If different manufacturing parameters are used in the first and second exposure development and etching processes, then the pattern density is improved, but the process consistency and accuracy deteriorate
Solution Approach 1:
The patent applies local quality by using different manufacturing parameters for different stages of the lithography process. The first exposure development process uses parameters optimized for forming the first set of patterns, while the second exposure development process uses parameters optimized for forming the second set of patterns. This localized optimization allows high pattern density to be achieved without compromising overall process consistency, as each stage is tuned for its specific purpose.
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 enhances the accuracy of semiconductor device fabrication by maintaining the critical dimension of trench openings and ensuring consistent process parameters across the first and second exposure development and etching processes.
Implementation Method 1
a first photoresist layer is formed on the etching stop layer, and a first lithography process is performed, to form a first patterned photoresist layer
Implementation Method 2
a first etching process is then performed, to form a plurality of first trenches in the etching stop layer
Data Source
AI summary
The present invention further provides a method for forming a semiconductor device, the method including: first, a target layer is provided, an etching stop layer is formed on the target layer, a top oxide layer is formed on the etching stop layer, afterwards, a first photoresist layer is formed on the top oxide layer, and a first etching process is then performed, to form a plurality of first trenches in the top oxide layer. Next, a second photoresist layer is formed on the top oxide layer, portion of the second photoresist layer fills in each first trench, a second etching process is then performed to form a plurality of second trenches in the top oxide layer, and using the remaining etching stop layer as a hard mask, a third etching process is performed to remove parts of the etching stop layer and parts of the target layer.