Recess Array Etching Selectivity via Segmented Metal Layer Mask
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Solution Overview
Problem
Conventional methods for forming recess array device structures in semiconductor substrates face challenges with non-selective etching, particularly at feature sizes of 20 nm or beyond, and require tall spacers to resist etching gases.
Innovation Solution
A method involving a metal layer with distinct portions is used, where the first portion covers the protruded second material and the second portion covers the base material, allowing for selective etching by controlling the etching gas concentration and applying protective layers to expose the base material for forming third recesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used for forming recess arrays in semiconductor substrates, then the etching process can be completed, but the etching selectivity deteriorates at feature sizes of 20 nm or beyond
Solution Approach 1:
The patent segments the etching process into multiple steps with different etching gases. The first etching gas is used to etch the semiconductor substrate, while the second etching gas is used to etch the sacrificial material. This segmentation allows each gas to be optimized for its specific target material, thereby maintaining high etching selectivity even at 20 nm and below feature sizes.
Solution Approach 2:
The patent changes the chemical parameters of the etching process by using different etching gases for different materials. The first etching gas is selected to have high reactivity with the semiconductor substrate, while the second etching gas is selected to have high reactivity with the sacrificial material. This parameter change enables precise control over etching selectivity across different feature sizes.
2Reliability
If tall spacers are used to resist etching gases, then the etching resistance is improved, but the device structure complexity increases
Solution Approach 1:
The patent extracts the etching resistance function from the spacer structure and transfers it to the sacrificial material. The sacrificial material is specifically designed and positioned to provide etching resistance during the etching process, eliminating the need for tall spacers and thereby reducing structural complexity while maintaining reliability.
Solution Approach 2:
The patent introduces a sacrificial material as an intermediary element that serves multiple functions: it provides etching resistance, defines the recess pattern, and is later removed to complete the structure. This intermediary approach simplifies the overall device structure compared to using tall spacers for etching protection.
3Manufacturing precision
If additional mask thickness is provided, then the etching precision is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent merges the mask function with the sacrificial material. The sacrificial material serves both as the pattern definition element and as the etching resistance provider. This merging eliminates the need for separate thick mask layers and complex mask formation processes, thereby improving etching precision without significantly increasing process complexity.
Solution Approach 2:
The sacrificial material is designed to perform multiple functions: it acts as the pattern template, provides etching resistance, and serves as a sacrificial element that is removed later. This multi-functionality reduces the number of separate process steps needed to achieve high etching precision, thereby avoiding excessive 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 enhances etching selectivity and reduces the need for tall spacers, providing additional mask thickness and improving the precision of recess formation, especially at smaller feature sizes.
Implementation Method 1
etching the base material according to the metal layer openings so as to form a plurality of third recesses
Implementation Method 2
the first portion covers the protruded second material... providing additional mask thickness
Data Source
AI summary
The present invention relates to a method for forming a recess array device structure in a semiconductor substrate. The method includes the steps of: providing a base material including a semiconductor substrate and a first material; forming a plurality of second recesses on the semiconductor substrate; forming a second material in the second recesses; forming a metal layer on the second material and the base material, wherein the metal layer includes a first portion and a second portion; removing the second portion to form a plurality of metal layer openings; to and etching the base material according to the metal layer openings so as to form a plurality of third recesses. Accordingly, the metal layer can overcome the non-selectivity issue during the etching process.