Electrostatic Chuck Voltage Control for Dust Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional plasma processing techniques fail to adequately address the issue of dust particles attaching to wafers during inter-step transitions in semiconductor manufacturing, leading to pattern defects and yield losses due to incomplete plasma production and temperature changes in the processing chamber.
Innovation Solution
A plasma processing apparatus that adjusts the wafer potential using an electrostatic chuck's voltage based on the charged balance of dust particles, effectively controlling the electrostatic force to reduce dust attachment by optimizing the potential distribution during inter-steps and initial wafer mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If voltage of electrostatic chuck is adjusted to control wafer potential, then dust particle attachment is reduced, but device complexity increases
Solution Approach 1:
The system monitors the charged balance of dust particles in the processing chamber and dynamically adjusts the electrostatic chuck voltage in response to detected changes, creating a closed-loop control system that adapts to varying dust conditions during inter-step transitions
Solution Approach 2:
The invention changes the electrical parameter (voltage) of the electrostatic chuck to control wafer potential, thereby modifying the electrostatic interaction between the wafer and dust particles to prevent harmful attachment
2Adaptability or versatility
If plasma production is halted between processing steps, then processing conditions can be changed, but dust particles attach to wafer due to temperature changes
Solution Approach 1:
The system applies a preventive electrostatic potential to the wafer before dust attachment can occur during inter-step transitions, counteracting the tendency of dust particles to attach due to temperature changes and plasma halt conditions
Solution Approach 2:
The electrostatic chuck voltage is dynamically adjusted during inter-step transitions based on the charged balance of dust particles, allowing the system to adapt to changing conditions while maintaining protection against dust attachment
3Object-affected harmful factors
If wafer potential is kept at zero to prevent electrostatic attraction, then charged dusts are repelled, but processing efficiency decreases due to extended plasma halt time
Solution Approach 1:
Instead of maintaining zero potential continuously, the system applies a controlled electrostatic potential only during the specific period when dust particles are present in the chamber, providing protection only when needed and minimizing impact on processing efficiency
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 significantly reduces the number of dust particles attaching to the wafer by balancing the charged particles' distribution, minimizing pattern defects and improving processing yields by maintaining plasma production continuity and controlling particle attachment.
Implementation Method 1
an electrode for electrostatically attracting a wafer onto a sample stage
Implementation Method 2
a high-frequency power supply for producing plasma
Implementation Method 3
a high-frequency bias power supply for accelerating an ion entering the wafer
Data Source
AI summary
A plasma processing apparatus includes a stage in a processing chamber where plasma is formed, a wafer to be processed, and an electrode arranged at an upper part of the stage and supplied with power to electrostatically attract and hold the wafer on the stage, and consecutively processing a plurality of wafers one by one. There are plural processing steps of conducting processing using the plasma under different conditions and there are plural periods when formation of plasma is stopped between the processing steps. An inner wall of the processing chamber is coated before starting the processing of any wafer, and voltage supplied to the electrode is changed according to a balance of respective polarities of particles floating and charged in the processing chamber in each period when formation of plasma is stopped.