Plasma Wafer Stage Voltage Control for Particle-Free Etching
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Solution Overview
Problem
In plasma processing for semiconductor devices and flat-panel displays, the shift in wafer potential due to changes in stage temperature or applied voltages leads to particle attraction, causing defects and yield degradation, as existing methods fail to consider the impact on wafer potential during temperature changes.
Innovation Solution
A plasma processing apparatus with a control system that adjusts DC voltages applied to electrodes to maintain the wafer potential close to 0 V, preventing particle adhesion by stepwise varying voltages based on calculated wafer potential shifts caused by temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If stage temperature is changed to control etch profile, then etching precision is improved, but wafer potential shifts causing particle adhesion
Solution Approach 1:
The patent applies parameter changes by adjusting DC voltages applied to electrodes in response to stage temperature changes. When temperature changes occur during etching, the control system modifies the voltage parameters to compensate for wafer potential shifts, thereby preventing particle adhesion while maintaining etch profile control
Solution Approach 2:
The patent implements feedback control by monitoring stage temperature and wafer potential, then adjusting DC voltages accordingly. The control system continuously responds to temperature changes by modifying electrode voltages to maintain proper wafer potential, creating a closed-loop system that prevents particle adhesion
2Stability of the object's composition
If DC voltages are adjusted to control adsorption force, then wafer holding stability is improved, but wafer potential shifts occur
Solution Approach 1:
The patent uses parameter changes by dynamically adjusting DC voltages to simultaneously maintain adsorption force and control wafer potential. The control system modifies voltage parameters based on stage temperature and wafer potential conditions, ensuring both stable wafer holding and prevention of particle adhesion
Solution Approach 2:
The patent applies dynamics by making the DC voltage applied to electrodes variable rather than fixed. The control system dynamically adjusts voltages in response to changing conditions (temperature, wafer potential), enabling adaptive control that maintains both adsorption stability and proper potential levels
3Stability of the object's composition
If electrode voltages are equalized to balance charge accumulation, then charge distribution is improved, but wafer potential control is insufficient
Solution Approach 1:
The patent applies parameter changes by transitioning from equal voltage distribution to asymmetric voltage distribution based on position. The control system adjusts voltages to specific ranges (higher for central electrodes, lower for peripheral electrodes) to simultaneously achieve charge balance and proper wafer potential control
Solution Approach 2:
The patent implements local quality by applying different voltage levels to different electrode groups based on their positions. Central electrodes receive higher voltages while peripheral electrodes receive lower voltages, creating a non-uniform voltage distribution that optimizes both charge accumulation and wafer potential for the entire wafer surface
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 ensures desired etch profiles and prevents yield degradation by effectively managing wafer potential, reducing particle adhesion and associated defects, thereby improving processing outcomes.
Implementation Method 1
a sample stage which is provided with electrodes for electrostatically adsorbing the sample
Implementation Method 2
source radio-frequency power for plasma generation is applied to turn the process gas into plasma
Data Source
AI summary
Provided is a plasma processing apparatus capable of obtaining desired etch profiles and preventing the degradation of yield rates due to the adhesion of particles, and equipped with a processing chamber in which a sample is plasma-treated; a radio-frequency power source for supplying radio-frequency power used to generate plasma; a sample stage which is provided with electrodes for electrostatically adsorbing the sample and on which the sample is mounted; and a DC power supply for applying DC voltages to the electrodes, the apparatus being further equipped with a control apparatus for controlling the DC power supply so as to apply such DC voltages as to decrease the absolute value of the potential of the sample in the absence of the plasma.