Electrostatic Chuck Wafer Holding via Heat Transfer Gas
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Solution Overview
Problem
Existing wafer processing methods face challenges in preventing particle generation due to temperature differences between the wafer and electrostatic chuck, leading to contamination and reduced processing yield, especially in plasma processing under reduced pressure, where gas requirements affect plasma treatment and chamber pressure control.
Innovation Solution
A method involving a wafer processing apparatus where a refrigerant is circulated through a sample stage to maintain the wafer in a non-contact position using an electrostatic chuck with a concave central portion and heat transfer gases are supplied to adjust temperature and pressure, minimizing particle generation and maintaining processing efficiency under reduced pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wafer is held in contact with the electrostatic chuck during processing, then the wafer can be securely held and positioned, but thermal expansion differences cause sliding between the wafer and chuck, generating particles that contaminate the film layer
Solution Approach 1:
A fluid (gas or liquid) is introduced between the wafer back surface and the electrostatic chuck surface, serving as an intermediary that prevents direct contact. This fluid layer eliminates thermal expansion-induced sliding while maintaining secure wafer holding through the combined effects of fluid pressure and electrostatic attraction, thereby preventing particle generation.
Solution Approach 2:
The invention utilizes pneumatic or hydraulic principles by introducing a pressurized fluid between the wafer and chuck. The fluid pressure creates a non-contact holding state that prevents sliding, while the electrostatic chuck maintains positional stability. This pneumatic/hydraulic intermediary layer solves the contradiction between secure holding and particle-free processing.
2Adaptability or versatility
If multiple processes with different temperature requirements are performed on the wafer, then diverse film layer processing is enabled, but repeated heating and cooling causes thermal expansion/contraction that leads to wafer-chuck sliding and particle generation
Solution Approach 1:
The fluid intermediary between the wafer and chuck prevents direct thermal contact, allowing the wafer to undergo thermal expansion and contraction during temperature cycling without transferring these movements to the chuck. This eliminates sliding-induced particle generation while enabling diverse temperature-based processing.
Solution Approach 2:
The invention changes the physical state parameters of the holding system by introducing a fluid medium that decouples the thermal and mechanical interactions. This allows independent optimization of processing temperatures for different film layers without compromising wafer-chuck interface stability.
3Object-generated harmful factors
If the wafer is held non-contact above the electrostatic chuck using fluid pressure, then particle generation from sliding is prevented, but the complexity of the holding system increases due to additional fluid supply and control mechanisms
Solution Approach 1:
The electrostatic chuck is designed to perform multiple functions simultaneously: it provides electrostatic attraction for wafer holding, serves as a temperature control interface through its back surface, and works in conjunction with the fluid system to prevent particle generation. This multi-functionality reduces the need for separate dedicated components.
Solution Approach 2:
The invention merges the electrostatic holding function with the fluid-based non-contact interface. The electrostatic chuck and fluid supply system work as an integrated holding mechanism, combining electromagnetic and pneumatic/hydraulic principles in a single unified system that achieves both secure holding and particle-free processing.
4Temperature
If heat transfer gas is supplied between the wafer and electrostatic chuck to control wafer temperature, then precise temperature control is achieved, but the gas supply system complexity and potential interference with plasma processing increase
Solution Approach 1:
Heat transfer gas is supplied locally at specific locations between the wafer and chuck, rather than uniformly across the entire interface. This localized gas supply achieves precise temperature control where needed while minimizing gas consumption and reducing potential interference with plasma processing in other areas.
Solution Approach 2:
The invention controls temperature by adjusting parameters of the heat transfer gas, such as flow rate, pressure, and temperature. By changing these gas parameters, precise wafer temperature control is achieved without requiring complex mechanical or thermal control systems.
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 effectively reduces particle generation and maintains processing efficiency by controlling temperature and pressure, improving yield and preventing contamination, while allowing for precise temperature adjustments and efficient plasma processing.
Implementation Method 1
a refrigerant supplied from a refrigerant supply device (9) to a refrigerant flow passage (24) disposed inside the sample stage (7) to circulate
Implementation Method 2
holding the wafer on an electrostatic chuck (21) disposed on an upper portion of the sample stage (7) to attract the wafer by an electrostatic force
Implementation Method 3
supplying a plurality of heat transfer gases (1303) having thermal conductivity from a heat transfer gas supply device (12) between the wafer (8) and the electrostatic chuck (21)
Implementation Method 4
causing a refrigerant supplied from a refrigerant supply device (9) to a refrigerant flow passage (24) disposed inside the sample stage (7) to circulate
Data Source
AI summary
Provided is a plasma processing apparatus including: a processing chamber; a sample stage placed inside the processing chamber; a processing gas supply unit which supplies processing gas into the processing chamber; a high-frequency power supply which supplies an electric field inside the processing chamber; an electrostatic chuck unit disposed on the sample stage in which openings to flow heat transfer gas are formed; a refrigerant supply unit which supplies a refrigerant inside the sample stage; and a control unit, wherein the control unit controls a heat transfer gas supply unit to control the temperature of a wafer depending on a plurality of processes for processing the wafer by switching a flow rate of the heat transfer gas or the type of the heat transfer gas flowing out of the openings between a concave portion formed in the electrostatic chuck unit and the wafer attracted to the electrostatic chuck unit.