Plasma processing apparatus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current plasma processing apparatuses face challenges in controlling wafer temperature over a wide range during high heat input etching processes with high wafer bias power, as existing temperature control units have limited temperature control range and are inefficient in maintaining in-plane uniformity.
Innovation Solution
A plasma processing apparatus with a refrigeration cycle that includes a compressor, condenser, and two expansion valves, where the refrigerant flow path functions as an evaporator, allowing for adjustable refrigerant pressure control through the first and second expansion valves, enabling wide-range temperature control without affecting in-plane uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional refrigerant supply unit with a single expansion valve is used, then the structure is simple, but the temperature control range is limited and cannot achieve wide-range temperature control
Solution Approach 1:
The refrigeration system is segmented into two independent expansion valves (first expansion valve and second expansion valve) instead of using a single expansion valve. The first expansion valve controls refrigerant flow to the condenser, while the second expansion valve controls refrigerant flow to the evaporator. This segmentation allows independent control of high-pressure and low-pressure sides, enabling wide-range temperature control from -30°C to +50°C.
Solution Approach 2:
The system dynamically switches between different expansion valve configurations based on temperature requirements. By independently adjusting the opening degrees of the first and second expansion valves, the system can adapt to various operating conditions and achieve optimal temperature control across a wide range, transforming the static single-valve system into a dynamic multi-valve control system.
2Temperature
If the refrigerant pressure is increased to raise evaporation temperature, then the temperature control range expands, but the electrostatic adsorption electrode may deform affecting wafer retention
Solution Approach 1:
The pressure control function is segmented between two expansion valves. The first expansion valve manages the high-pressure side (condenser) while the second expansion valve manages the low-pressure side (evaporator). This allows the system to maintain appropriate pressure differentials without excessive pressure increases in the evaporator, preventing electrode deformation while achieving wide temperature control range.
Solution Approach 2:
The system changes the operating parameters (pressure and temperature) of the refrigerant by independently controlling two expansion valves. By adjusting the opening degrees of both valves, the system can achieve various combinations of evaporation temperature and pressure, selecting optimal parameter sets that provide wide temperature control without causing electrode deformation.
3Speed
If a direct expansion type refrigerant supply unit is used, then high-speed temperature control is achieved, but the temperature control range is limited to low-pressure side
Solution Approach 1:
The system dynamically coordinates both expansion valves to achieve high-speed temperature control across a wide range. The first expansion valve rapidly adjusts condenser pressure while the second expansion valve simultaneously adjusts evaporator pressure, enabling the system to respond quickly to temperature changes while maintaining control over both low and high temperature ranges.
Solution Approach 2:
The dual expansion valve configuration gives the system universal temperature control capability, making it suitable for both low-temperature cooling and high-temperature heating operations. The system can function as a complete heat pump cycle, providing both cooling and heating with high-speed response, rather than being limited to cooling only.
4Productivity
If high heat input etching process is applied to increase throughput, then processing efficiency improves, but wafer temperature control becomes difficult
Solution Approach 1:
The system utilizes the phase transition of refrigerant (liquid to vapor) in the evaporator to provide efficient heat absorption from the electrostatic adsorption electrode. This phase change process enables high heat input etching by rapidly removing excess heat from the wafer surface, maintaining temperature control even during high-power plasma processing that increases throughput.
Solution Approach 2:
The refrigerant acts as an intermediary heat transfer medium between the electrostatic adsorption electrode and the cooling system. Through the refrigeration cycle with dual expansion valves, the refrigerant efficiently carries heat away from the wafer during high heat input etching, enabling the system to sustain high processing power while maintaining precise temperature control.
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 configuration allows for rapid and precise control of wafer temperature over a wide range during high heat input etching, maintaining in-plane uniformity and enhancing processing accuracy and throughput.
Implementation Method 1
The direct expansion type refrigerant supply unit (or refrigeration cycle) makes it possible to control the semiconductor wafer temperature prevailing during a high heat input etching process at high speed and with high efficiency by making use of evaporative latent heat of the refrigerant
Implementation Method 2
a compressor, which uses a refrigerant circulation system to pressurizes the refrigerant
Implementation Method 3
a condenser, which condenses the pressurized refrigerant
Data Source
AI summary
The present invention provides a temperature control unit for an electrostatic adsorption electrode that is capable of controlling the wafer temperature rapidly over a wide temperature range without affecting in-plane uniformity while high heat input etching is conducted with high wafer bias power applied. A refrigerant flow path provided in the electrostatic adsorption electrode serves as an evaporator. The refrigerant flow path is connected to a compressor, a condenser, and a first expansion valve to form a direct expansion type refrigeration cycle. A second expansion valve is installed between the electrostatic adsorption electrode and the compressor to adjust the flow rate of a refrigerant. This makes it possible to compress the refrigerant in the refrigerant flow path of the electrostatic adsorption electrode and adjust the wafer temperature to a high level by raising the refrigerant evaporation temperature. Further, a thin-walled cylindrical refrigerant flow path is employed so that the thin-walled cylinder is deformed only slightly by the refrigerant pressure.