Built-In Ring Resonance Tuning for Wafer Edge Etching Uniformity
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Solution Overview
Problem
Conventional etching machines face challenges in maintaining etching uniformity at the edge of a wafer due to erosion of the focusing ring and mismatched plasma conditions, leading to inconsistent etching rates and directions.
Innovation Solution
An etching uniformity regulating device comprising an inductor and a capacitor connected in parallel, where the inductor has a self-resonance frequency greater than the lower electrode radio-frequency power supply frequency, and an adjustable capacitor is used to regulate the capacitance, ensuring the resonance frequency matches the power supply frequency, thus controlling the edge electric field and etching rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a focusing ring and built-in ring are disposed around an electrostatic chuck to achieve perpendicular electric field at the wafer edge, then etching uniformity is improved, but the focusing ring erodes over time causing thickness reduction and electric field tilt
Solution Approach 1:
The patent changes the electrical parameters of the built-in ring by connecting it to ground through an RC circuit (resistor and capacitor). This modifies the electrical characteristics and potential distribution of the built-in ring, allowing dynamic adjustment of the electric field at the wafer edge to compensate for focusing ring erosion and maintain etching uniformity throughout the focusing ring's service life.
2Manufacturing precision
If a specific arrangement of focusing ring and built-in ring is used to match plasma conditions, then etching uniformity is improved, but the device cannot adapt to multiple different plasma conditions
Solution Approach 1:
The patent introduces dynamic elements (resistor and capacitor) into the built-in ring circuit, transforming it from a static structure to a dynamically adjustable system. The RC circuit allows the electrical characteristics of the built-in ring to be adjusted in response to different plasma conditions, enabling the device to maintain etching uniformity across multiple processes without requiring physical replacement of components.
Solution Approach 2:
By changing the electrical parameters through the RC circuit connection, the system can adapt its behavior to match different plasma conditions. The resistor and capacitor values can be selected to optimize performance for various etching processes, providing versatility 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 solution achieves consistent etching rates at the edge and center of the wafer by dynamically adjusting the capacitance to match the resonance frequency with the power supply frequency, thereby maintaining uniformity across different plasma conditions.
Implementation Method 1
determining whether a resonance frequency of the etching uniformity regulating device is equal to the frequency of a lower electrode radio-frequency power supply of an etching machine; and when a determining result is no, regulating a capacitance of the capacitor of the etching uniformity regulating device, so that the resonance frequency of the etching uniformity regulating device approaches the frequency of the lower electrode radio-frequency power supply
Implementation Method 2
a focusing ring and a built-in ring are disposed around an electrostatic chuck of a conventional etching machine
Data Source
AI summary
An etching uniformity regulating device and method. The device comprises an inductor and a capacitor connected in parallel. One end of the etching uniformity regulating device is connected to a built-in ring located at the edge of an electrostatic chuck of an etching machine, and the other end is grounded. The purpose of controlling the edge electric field is achieved by regulating a capacitance of the capacitor, so as to regulate the etching rate of the edge, thereby achieving etching uniformity.