Electrostatic Chuck Two-Step Voltage Attraction
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Solution Overview
Problem
Existing substrate processing methods using electrostatic chucks face challenges in reducing particle generation due to thermal expansion differences between the chuck and the wafer, which also lead to reduced throughput, either through preheating the wafer or temperature control of the chuck, as these methods require additional time and can cause wear on the wafer.
Innovation Solution
A method involving a two-step voltage application to the electrostatic chuck, starting with a lower voltage for initial attraction and increasing to a higher voltage once the temperature difference between the chuck and the wafer is minimized to 30 degrees C or less, while maintaining a constant chuck temperature, to reduce thermal expansion and particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the wafer is preheated before attraction or the chuck temperature is controlled to minimize thermal expansion, then particle generation is reduced, but processing throughput decreases due to additional time requirements
Solution Approach 1:
The wafer is pre-heated on the heating plate before being transferred to the electrostatic chuck. This preliminary heating action reduces the temperature difference between wafer and chuck during attraction, minimizing thermal expansion differences and particle generation without requiring temperature control of the electrostatic chuck itself, thus maintaining high throughput
Solution Approach 2:
The heating function is segmented into a separate heating plate component distinct from the electrostatic chuck. The heating plate performs preliminary heating while the electrostatic chuck maintains a fixed temperature, allowing independent optimization of both functions without compromising throughput
2Force
If a high DC voltage is applied immediately to attract the substrate, then attraction force is sufficient, but thermal expansion differences cause increased particle generation and wafer wear
Solution Approach 1:
The wafer is pre-heated before attraction to reduce the temperature difference between wafer and chuck. This preliminary thermal preparation minimizes thermal expansion during the high-voltage attraction phase, reducing particle generation and wafer wear while maintaining sufficient attraction force
Solution Approach 2:
By pre-heating the wafer on the heating plate, the system cushions against the harmful effects of thermal expansion during attraction. The temperature difference is reduced in advance, creating a protective effect that prevents particle generation and wafer wear during the high-stress attraction phase
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 improves processing throughput by minimizing thermal expansion-induced wear and allowing efficient temperature adjustment of the wafer without the need for preheating or extensive temperature control of the chuck.
Implementation Method 1
a first attraction step of attracting the substrate onto the electrostatic chuck by applying a first direct current (DC) voltage to the electrostatic chuck
Implementation Method 2
a holding step of holding the attraction of the substrate by the electrostatic chuck while applying the first DC voltage to the electrostatic chuck, until a temperature difference between the electrostatic chuck and the substrate becomes 30 degrees C. or less
Data Source
AI summary
A method of processing a substrate includes: a placement step of placing the substrate on an electrostatic chuck set to have a predetermined temperature; a first attraction step of attracting the substrate onto the electrostatic chuck by applying a first direct current (DC) voltage to the electrostatic chuck; a holding step of holding the attraction of the substrate by the electrostatic chuck while applying the first DC voltage to the electrostatic chuck, until a temperature difference between the electrostatic chuck and the substrate becomes 30 degrees C. or less; and a second attraction step of attracting the substrate onto the electrostatic chuck by applying a second DC voltage, which is higher than the first DC voltage, to the electrostatic chuck.