Electric-Field Wet Etching for Directional Wafer Patterning
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Solution Overview
Problem
As semiconductor device manufacturing scales down, wet etching becomes challenging due to the difficulty in achieving directional etching, leading to issues of under-etching and over-etching.
Innovation Solution
A wet etch apparatus is designed to utilize an electric field to control the diffusion of the chemical solution, thereby enhancing the directionality of the etching process. This is achieved by generating an electric field across the substrate during the wet etching process, which influences the movement of ions and polar molecules in the solution, allowing for controlled lateral or vertical etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wet etching is used, then the etching process is simple and easy to perform, but the directionality of etching is poor leading to under-etching and over-etching
Solution Approach 1:
An electric field is introduced as an intermediary between the chemical solution and the substrate to control the movement of ions and polar molecules. The electric field generator creates an electric field that influences the diffusion direction of charged species in the chemical solution, thereby achieving directional etching without fundamentally changing the wet etching process itself.
Solution Approach 2:
The patent changes the physical state of the etching environment by applying an electric field, which alters the movement behavior of ions and polar molecules in the chemical solution. By controlling the electric field strength and direction, the diffusion directionality of the etchant is modified, enabling precise control over etching direction while maintaining the chemical etching mechanism.
2Manufacturing precision
If the chemical solution is allowed to diffuse freely, then the etching process is fast and efficient, but the directionality control is lost
Solution Approach 1:
The electric field serves as a mediator that guides the diffusion of ions and polar molecules without blocking their movement. It provides directional guidance while maintaining the dynamic nature of diffusion, allowing the chemical solution to remain active and efficient while achieving controlled directionality in the etching process.
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
The controlled directionality of the wet etching process effectively addresses the issues of under-etching and over-etching, improving the precision and efficiency of the etching process, and enhancing the source/drain proximity in semiconductor devices.
Implementation Method 1
generating an electric field across the substrate during the wet etching process, which influences the movement of ions and polar molecules in the solution
Implementation Method 2
the charged ions in the chemical solution are moved in response to the electric field
Data Source
AI summary
A wet etch apparatus includes a wafer chuck, a dispensing nozzle, a liquid etchant container, and an electric field generator. The dispensing nozzle is above the wafer chuck. The liquid etchant container is in fluid communication with the dispensing nozzle. The electric field generator is operative to generate an electric field across the wafer chuck. The electric field generator includes a first electrode and a second electrode spaced apart from the first electrode in a direction substantially perpendicular to a top surface of the wafer chuck, and the second electrode is an electrode plate above the wafer chuck.