Semiconductor Trench Formation via Unified Etching
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Solution Overview
Problem
The challenge in semiconductor device fabrication is forming trenches with similar contours in dense and peripheral regions with fewer patterning processes to prevent inaccurate alignment during the lithography process.
Innovation Solution
A method involving multiple etching processes with specific angles and etchant selection to form trenches with controlled angles between the sidewalls and the substrate surface, using a mask layer to expose and remove material layers, and filling the trenches with insulating layers to achieve similar contours in both regions with reduced lithography processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate patterning processes are performed for dense region and peripheral region, then trenches can be formed with similar contours, but inaccurate alignment occurs during the separate patterning processes
Solution Approach 1:
The patent combines the patterning processes for dense region and peripheral region into a single unified patterning step. By forming a common mandrel structure that defines trenches in both regions simultaneously, the method eliminates alignment errors between separate patterning processes while maintaining similar trench contours in both dense and peripheral regions.
2Reliability
If multiple patterning processes are performed to form trenches in different regions, then accurate alignment can be achieved, but the number of lithography processes increases
Solution Approach 1:
The patent merges multiple patterning operations into a single lithography process by using a common mandrel structure. This unified approach forms trenches in both dense and peripheral regions simultaneously, reducing the number of lithography processes from multiple separate steps to just one process while maintaining accurate alignment.
Solution Approach 2:
The patent performs preliminary formation of a common mandrel structure that pre-defines the trench patterns for both dense and peripheral regions. This preliminary action establishes the trench locations and contours before any region-specific processing, eliminating the need for subsequent patterning steps in different regions.
3Productivity
If a single patterning process is used for both dense and peripheral regions, then the number of lithography processes is reduced, but trenches with similar contours cannot be formed in both regions
Solution Approach 1:
The patent applies local quality by forming a common mandrel structure with region-specific characteristics. The mandrel is designed with different sections that correspond to dense and peripheral regions, where each section has local properties optimized for its specific region. This allows a single patterning process to produce trenches with appropriate contours for both dense and peripheral regions simultaneously.
Data Source
AI summary
Provided is a method of fabricating a semiconductor device, including the following. A first material layer, a second material layer and a mask layer are formed on a substrate. A portion of the second material layer is removed by performing a first etching process with the mask layer as a mask, so as to expose the first material layer and form a first pattern layer and a second pattern layer. A portion of the first material layer is removed by performing a second etching process with the mask layer as a mask, so as to expose a portion of the substrate. A portion of the substrate is removed by performing a third etching process with the mask layer as a mask, so as to form first trenches and second trenches. Sidewalls of the second trenches and a surface of the substrate form at least two different angles.