Trench Etching via Selective Barrier Layer Formation
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Solution Overview
Problem
As semiconductor devices become increasingly integrated and require smaller dimensions, the etching process for forming trenches or holes often results in increased width, leading to damage or bridge formation, compromising the reliability and critical dimension of the device.
Innovation Solution
A method is developed where only the lower portion of the trench or hole is etched by using a first and second amount of etching gas with different pressures and energies to form a barrier layer, preventing the upper portion from being etched and maintaining the integrity of the trench dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching process is used to form trench, then trench can be formed, but width of trench increases leading to damage or bridge formation
Solution Approach 1:
The etching process is segmented into two distinct stages: a first etching process that etches the upper portion of the trench to a first depth, and a second etching process that etches the lower portion to a second depth greater than the first depth. This segmentation allows independent control of upper and lower trench dimensions, preventing width increase and bridge formation while maintaining manufacturing precision and device reliability
Solution Approach 2:
A preliminary reaction layer is formed conformally on the trench surface before the etching processes. This reaction layer serves as a protective barrier during the first etching process, preventing width increase at the upper portion. The preliminary action of forming this protective layer enables subsequent selective etching without compromising trench integrity
2Ease of manufacture
If etching process is performed to form trench, then trench is created, but peripheral device may be exposed resulting in damages
Solution Approach 1:
The etching process is divided into two depth stages, with the first etching process reaching only to a first depth that stops before exposing peripheral devices, and a second etching process that selectively etches the lower portion. This segmentation prevents peripheral device exposure and associated damages while still achieving the required trench formation
Solution Approach 2:
A reaction layer is introduced as an intermediary protective barrier on the trench surface. This reaction layer prevents over-etching and protects peripheral devices from exposure during the etching process, eliminating the harmful effect of device exposure while maintaining ease of trench manufacture
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 reliability of semiconductor devices by selectively etching the lower portion of the trench, preventing increased critical dimensions and maintaining the precision of the trench structure, thus improving the overall performance and reliability of the semiconductor device.
Implementation Method 1
etching an oxide layer to form a trench therein
Implementation Method 2
forming a barrier layer by reacting a first amount of etching gas with the first region of the first reaction layer
Data Source
AI summary
A method for forming a trench includes etching an oxide layer to form a trench therein, conformally forming a first reaction layer along a surface of the trench, the first reaction layer including a first region on an upper portion of the trench and a second region on a lower portion of the trench, forming a barrier layer by reacting a first amount of etching gas with the first region of the first reaction layer, and etching the oxide layer on a lower portion of the second region by reacting a second amount of etching gas with the second region of the first reaction layer, the second amount of etching gas being greater than the first amount of etching gas.