Selective Semiconductor Etching via Noble Metal Catalyst
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Solution Overview
Problem
Blade dicing methods for singulating semiconductor substrates into chips become inefficient as chip size decreases and the number of dicing grooves increases, leading to prolonged processing times, while existing etching methods like Metal-Assisted Chemical Etching (MacEtch) struggle with achieving high etching selectivity and rate.
Innovation Solution
An etching method involving a semiconductor substrate with a metal layer and a noble metal catalyst layer, using an etchant containing hydrofluoric acid, an oxidizer, and a buffer to selectively etch the substrate, and an etching apparatus to control the replenishment of oxidizer and buffer for optimal etching conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If blade dicing is used to singulate semiconductor substrates, then chips can be separated into individual units, but processing time prolongs as chip size decreases and number of dicing grooves increases
Solution Approach 1:
The patent replaces the mechanical blade dicing system with a chemical etching system. Instead of using a rotating blade to mechanically cut the substrate, the invention uses a chemical etchant to selectively remove material and form dicing grooves. This substitution of mechanical action with chemical action enables parallel processing of multiple grooves simultaneously, dramatically reducing processing time while maintaining cutting precision.
Solution Approach 2:
The patent changes the fundamental parameter of the dicing process from mechanical force to chemical reactivity. By controlling etchant composition, temperature, and exposure time, the process achieves high-speed singulation. The chemical etching rate can be precisely controlled through parameter adjustment, allowing optimization of both speed and precision without the mechanical constraints of blade dicing.
2Manufacturing precision
If Metal-Assisted Chemical Etching (MacEtch) is used to etch semiconductor substrates, then deep holes with high aspect ratio can be formed, but etching selectivity and rate are insufficient
Solution Approach 1:
The patent employs a composite etchant system combining multiple chemical components (hydrofluoric acid, nitric acid, acetic acid, and hydrogen peroxide) working synergistically. This composite chemical system provides both the high etching rate needed for productivity and the selectivity required for precise deep hole formation. The combination of different acids and oxidizing agents creates a balanced etching environment that achieves high aspect ratio structures at improved rates compared to traditional MacEtch methods.
Solution Approach 2:
The patent incorporates hydrogen peroxide as a strong oxidizing agent in the etchant composition. This oxidizer accelerates the etching reaction by providing additional oxidative power, thereby increasing the overall etching rate. The presence of the strong oxidant enables faster material removal while maintaining the catalytic action of noble metals, resolving the contradiction between etching speed and precision.
3Manufacturing precision
If etchant composition changes during the etching process, then etching uniformity deteriorates, but maintaining constant composition requires continuous replenishment
Solution Approach 1:
The patent implements a feedback control system for etchant replenishment. Sensors monitor the composition and consumption rate of etchant components during the etching process, and this information feeds back to a control system that automatically adjusts the replenishment rate. This closed-loop control maintains constant etchant composition throughout the process, ensuring uniform etching results while optimizing the replenishment strategy to avoid unnecessary complexity.
Solution Approach 2:
The patent designs an etchant system with self-regulating properties where the etching byproducts and consumption patterns are predictable and can be compensated through pre-programmed replenishment schedules. The system partially automates itself by using the etching process characteristics to guide replenishment timing and quantity, reducing the need for complex real-time monitoring while maintaining etching uniformity.
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 high etching selectivity and rate, reducing processing time and improving yield by selectively etching the semiconductor substrate, allowing for efficient chip singulation and minimizing the influence of etchant composition changes.
Implementation Method 1
supplying an etchant containing hydrofluoric acid, an oxidizer, and a buffer to a semiconductor substrate... thereby etching the semiconductor substrate
Implementation Method 2
etching is performed by using this noble metal as a catalyst... using an etchant containing hydrofluoric acid, an oxidizer
Implementation Method 3
a discontinuous film made of a noble metal is formed on a semiconductor substrate, and etching is performed by using this noble metal as a catalyst
Implementation Method 4
supplying an etchant containing hydrofluoric acid, an oxidizer, and a buffer... minimizing the influence of etchant composition changes
Data Source
AI summary
An etching method according to an embodiment includes supplying an etchant containing hydrofluoric acid, an oxidizer, and a buffer to a semiconductor substrate including a first region covered with a metal layer made of one or more metals other than noble metals, and a second region covered with a catalyst layer made of a noble metal, such that the etchant comes in contact with the catalyst layer and the metal layer, thereby etching the semiconductor substrate at a position of the catalyst layer.