Metal-Assisted Chemical Etching Catalyst Layer Design
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Solution Overview
Problem
Metal-assisted chemical etching (MacEtch) faces challenges in forming high aspect ratio holes in semiconductor substrates due to issues like needle-like residual portions and incomplete etching, which affect the quality and yield of semiconductor chips.
Innovation Solution
A catalyst layer with distinct first and second portions, where the first portion has a higher apparent density and is thinner, and the second portion has a lower apparent density and is thicker, is formed on the semiconductor surface, using a combination of noble metals and other metals, and an etchant is supplied to assist in the etching process, preventing the formation of needle-like residual portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer catalyst layer is used in MacEtch, then the etching process is simple, but needle-like residual portions form and etching is incomplete
Solution Approach 1:
The catalyst layer is divided into two distinct portions: a first portion with higher apparent density and thinner thickness, and a second portion with lower apparent density and greater thickness. This segmentation allows each portion to perform different functions - the first portion provides structural support while the second portion enables complete etching by preventing needle-like residual portions from forming.
2Stability of the object's composition
If the catalyst layer is made uniformly dense, then the structure is stable, but etching completeness is reduced due to residual portions
Solution Approach 1:
Different regions of the catalyst layer are given different apparent densities and thicknesses to optimize local functions. The first portion has higher density for stability, while the second portion has lower density to facilitate complete etching. This local differentiation of properties resolves the contradiction between overall stability and local etching effectiveness.
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 enables efficient etching of semiconductor surfaces with reduced residual portions, improving the quality and yield of semiconductor chips by ensuring complete etching and preventing dust formation.
Implementation Method 1
Metal-assisted chemical etching (MacEtch) is a method of etching a semiconductor surface using a noble metal as a catalyst
Data Source
AI summary
An etching method according to an embodiment includes forming a catalyst layer made of a first noble metal or the combination of the second noble metal and the metal other than noble metals on a surface made of a semiconductor, the catalyst layer including a first portion and a second portion, the first portion covering at least a part of the surface, the second portion being located on the first portion, having an apparent density lower than that of the first portion, and being thicker than the first portion; and supplying an etchant to the catalyst layer to cause an etching of the surface with an assist from the catalyst layer as a catalyst.