Clean-Then-Etch Process for Semiconductor Recess Regions
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Solution Overview
Problem
As semiconductor devices are scaled down, short channel effects lead to deteriorating operation characteristics, and existing methods fail to effectively remove etching objects without deforming underlying structures during the wet etch process.
Innovation Solution
A clean-then-etch process is employed, where a cleaning solution is used to fill recess regions and then a wet etch process is performed with a diluted etching solution, maintaining a lower concentration within the recess regions to prevent deformation of the underlying structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a wet etch process is performed to remove etching objects, then the etching objects are effectively removed, but the underlying structure in recess regions deforms due to excessive etching
Solution Approach 1:
The patent applies local quality by maintaining different etching solution concentrations in different regions: high concentration outside recess regions for effective etching object removal, and low concentration inside recess regions to prevent deformation of underlying structures. This spatial variation in etching aggressiveness resolves the contradiction between removal efficiency and structure preservation.
Solution Approach 2:
The patent introduces a cleaning solution as an intermediary substance that fills recess regions before the etch process. This cleaning solution acts as a protective mediator, diluting the etching solution concentration inside recess regions and preventing direct contact between high-concentration etching solution and the underlying structure, thereby preventing deformation while allowing effective etching outside.
2Productivity
If the etching solution concentration is increased to improve etching speed, then productivity increases, but deformation of the underlying structure worsens
Solution Approach 1:
The patent implements local quality by creating spatially varying etching solution concentrations: high concentration in non-recess areas for fast etching, and low concentration in recess areas for structure protection. This resolves the contradiction between etching speed and deformation prevention by optimizing concentration locally rather than uniformly.
Solution Approach 2:
The patent changes the concentration parameter of the etching solution based on location. By controlling the cleaning solution volume to achieve complete filling of recess regions, the system dynamically adjusts the effective etching solution concentration in recess areas versus non-recess areas, enabling high productivity without structure deformation.
3Reliability
If a cleaning process is performed before etching, then the substrate is cleaned, but additional process time is required
Solution Approach 1:
The patent merges the cleaning process and etching process into a single integrated operation. The cleaning solution is applied and simultaneously serves as a concentration-modifying agent during etching, eliminating the need for separate cleaning and etching steps. This resolves the contradiction between achieving cleaning benefits and maintaining process efficiency.
Solution Approach 2:
The cleaning solution performs multiple functions: it cleans the substrate surface and simultaneously acts as a concentration buffer in recess regions during etching. This multi-functionality eliminates redundant process steps and resolves the time loss contradiction while maintaining etching uniformity through concentration control.
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 method effectively removes etching objects outside recess regions while preventing or reducing etching and deformation of the inner parts of the recess regions, thereby improving the reliability of semiconductor devices.
Implementation Method 1
providing a cleaning solution to a whole surface of the substrate, the cleaning solution filling at least a portion of the recess region
Implementation Method 2
a portion of the cleaning solution mixed with a portion of the etching solution introduced into the recess region during the wet etch process, thereby diluting the etching solution concentration within the recess region
Data Source
AI summary
An etching method is disclosed. The etching method comprises providing on a substrate a structure comprising a recess region formed therein. The recess region includes an inner part and a mouth part whose width is less than that of the inner part. The etching method further comprises performing a clean-then-etch process to remove at least a portion of etching object formed outside the recess region. The performing a clean-then-etch process comprises performing a cleaning process to fill at least a portion of the recess region with a cleaning solution, and performing a wet etch process to the substrate in a state that the cleaning solution remains in the recess region.