Nonsinusoidal Bias Voltage for Plasma Etch Uniformity
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Solution Overview
Problem
As semiconductor device patterns become smaller, achieving uniformity in plasma etching becomes increasingly challenging due to variations in etch performance across fine recess patterns, necessitating more precise control of plasma processes.
Innovation Solution
A plasma processing method and apparatus that apply a nonsinusoidal wave voltage with a DC pulse and ramp portion to the lower electrode, allowing for adjustment of the slope and duration ratio of the ramp portion to control ion energy distribution and minimize etch differences between pattern openings, thereby improving etch uniformity and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching is used, then etching can be performed, but etch uniformity deteriorates as patterns get smaller
Solution Approach 1:
The patent applies a dynamic voltage waveform with a ramp portion and DC pulse portion to the lower electrode, enabling real-time modulation of ion energy distribution. This dynamic control allows the plasma process to adapt to varying pattern sizes and maintain etch uniformity across different feature dimensions, resolving the contradiction between etch uniformity and pattern size scalability
Solution Approach 2:
The patent changes the voltage waveform parameters (slope of ramp portion, duration ratio of ramp portion to cycle) to control ion energy distribution. By adjusting these parameters, the system optimizes etch performance for different pattern sizes, improving manufacturing precision while maintaining adaptability to various pattern geometries
2Manufacturing precision
If precise plasma control is implemented, then etch uniformity improves, but process complexity increases
Solution Approach 1:
The patent employs a periodic voltage waveform with defined ramp and DC pulse portions applied to the lower electrode. This periodic structure provides systematic control over ion energy distribution, achieving precise plasma control and improved etch uniformity through a manageable, repeating cycle rather than continuous complex adjustments
Solution Approach 2:
The patent controls plasma parameters by adjusting specific waveform characteristics (slope and duration ratio) rather than managing multiple independent variables. This focused parameter control achieves precise plasma management with reduced operational complexity, as only key waveform parameters need optimization
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 method enhances etch performance by achieving uniform ion energy distribution, reducing intra-cell loading, and improving etch rate and selectivity, leading to more consistent pattern formation in semiconductor devices.
Implementation Method 1
A plasma power is applied to form plasma within the chamber
Implementation Method 2
controlling an ion energy distribution generated at a surface of the substrate
Data Source
AI summary
In a plasma processing method, a substrate is loaded onto a lower electrode within a chamber. A plasma power is applied to form plasma within the chamber. A voltage function of a nonsinusoidal wave having a DC pulse portion and a ramp portion is generated. Generating the voltage function may include setting a slope of the ramp portion and setting a duration ratio of the ramp portion to a cycle of the voltage function in order to control an ion energy distribution generated at a surface of the substrate. A bias power of the nonsinusoidal wave is applied to the lower electrode.