Electrostatic Chuck Thermal Control Calibration
Solution Overview
Problem
Plasma processing systems face challenges in achieving high uniformity and repeatability in semiconductor substrate processing, particularly in controlling the temperature of electrostatic chucks to maintain critical dimension uniformity across wafers, which requires improved spatial resolution and self-diagnostics.
Innovation Solution
A method involving a control unit with a processor to set and measure temperature levels of thermal control elements in an electrostatic chuck, calculate system responses, invert them, and calibrate the elements to optimize power input, allowing for precise temperature control and calibration without in situ measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional temperature control methods are used for electrostatic chucks, then the system is simpler to operate, but the temperature uniformity and spatial resolution are insufficient
Solution Approach 1:
The electrostatic chuck is divided into multiple independently controllable heater zones, allowing each zone to be controlled separately to achieve high spatial resolution temperature profiles across the substrate surface
Solution Approach 2:
The system measures temperature responses at different power levels and calculates system response matrices that are inverted to determine the exact power distribution needed for any desired temperature profile, enabling precise temperature control through mathematical parameter transformation
2Measurement precision
If in situ temperature measurements are performed during processing, then real-time temperature data is obtained, but the measurements are affected by noise and require costly diagnostic tools
Solution Approach 1:
The system performs calibration measurements before actual substrate processing to establish system response matrices. These pre-established matrices are then used during processing to calculate power inputs without requiring noisy in situ temperature measurements
Solution Approach 2:
The calibration process creates a mathematical model (system response matrix) that replicates the thermal behavior of the chuck. This model allows the system to predict temperature outcomes from power inputs without requiring physical temperature sensors during processing
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 enhances the accuracy and repeatability of substrate processing by stabilizing and controlling wafer temperatures, maximizing chip yield and reducing the need for costly diagnostic tools, while improving the precision of temperature control and overcoming noise issues in IR images.
Implementation Method 1
setting, with a control unit including a processor, the at least one thermal control element in the electrostatic chuck to a first predetermined power level; measuring, with a temperature detector, a first temperature of the at least one thermal control element when the at least one thermal control element is powered at the first predetermined power level
Data Source
AI summary
A method for calculating power input to at least one thermal control element of an electrostatic chuck includes: setting the at least one thermal control element to a first predetermined power level; measuring a first temperature of the at least one thermal control element when the at least one thermal control element is powered at the first predetermined power level; setting the at least one thermal control element to a second predetermined power level; measuring a second temperature of the at least one thermal control element when the at least one thermal control element is powered at the second predetermined power level; calculating a difference between the first temperature and the second temperature; calculating a system response of the at least one thermal control element based on the difference; inverting the system response; and calibrating the at least one thermal control element based on the inverted system response.