Electrostatic Chuck Calibration for Sparse-Sensor Temperature Profiles
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Solution Overview
Problem
Substrate processing systems face challenges in accurately controlling temperatures across electrostatic chucks due to non-uniformities in heating plates, leading to variations in substrate temperatures and limited control over thermal energy transfer, which can result in non-uniform critical dimensions and variability between processing chambers.
Innovation Solution
A system and method that utilize a controller, interface, and calibration controller to select and adjust thermal control elements based on feedback signals from sensors, generating calibration values to estimate substrate temperatures and account for distributed thermal energy contributions, allowing for arbitrary temperature distribution criteria and ESC matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a limited number of sensors are used to monitor temperature, then device complexity is reduced, but measurement precision deteriorates due to insufficient spatial coverage
Solution Approach 1:
The patent creates a virtual temperature map by copying and extrapolating temperature data from limited physical sensors across the entire substrate surface. A calibration model is established that maps sensor readings to estimated temperatures at multiple locations, effectively creating a digital replica of the thermal field without requiring physical sensors at every point.
Solution Approach 2:
The patent replaces the mechanical/physical system of densely packing temperature sensors with a computational model that uses mathematical algorithms to estimate temperature distribution. The calibration controller uses measured temperatures from limited sensors, along with chamber geometry and heating element characteristics, to calculate temperatures at unmeasured locations through interpolation and extrapolation.
2Stability of the object's composition
If thermal control elements are adjusted to compensate for non-uniformities, then temperature uniformity improves, but device complexity increases due to additional calibration requirements
Solution Approach 1:
The patent performs preliminary calibration of the thermal control system before actual substrate processing. During this calibration phase, the system characterizes the thermal field by measuring temperatures at various locations with a reference substrate, identifies non-uniformities, and pre-computes compensation profiles that are stored for use during production processing, eliminating the need for complex real-time adjustments.
Solution Approach 2:
The patent implements a feedback mechanism where temperature measurements from sensors are continuously compared against target temperature values, and the calibration controller automatically adjusts thermal control element parameters to minimize deviations. This closed-loop control system uses the calibration model to predict the effect of adjustments and optimize temperature uniformity.
3Measurement precision
If calibration values are generated for each sensor to account for field contributions, then measurement precision improves, but loss of time increases due to extended calibration procedures
Solution Approach 1:
The patent performs comprehensive sensor calibration in advance during a dedicated calibration phase before production runs. During this preliminary action, each sensor's response to known thermal fields from various heating elements is characterized and calibration factors are computed and stored. This pre-calibration approach trades initial setup time for rapid, accurate measurements during actual processing without repeated calibration overhead.
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 provides precise temperature control across electrostatic chucks, ensuring uniform substrate temperatures and enabling ESC matching, thereby overcoming limitations in existing calibration processes and accounting for differences between processing chambers.
Implementation Method 1
a heating plate, where the heating plate includes a plurality of temperature controlled zones and a plurality of sensor elements
Implementation Method 2
A substrate may be arranged on a pedestal, an electrostatic chuck (ESC), etc. in a processing chamber
Data Source
AI summary
A system includes sensors, an interface and a controller. The interface receives feedback signals from the sensors. At least some of the sensors are disposed in an electrostatic chuck. The feedback signals are indicative respectively of fields of a heating plate of the electrostatic chuck. The controller, based on the fields and sets of calibration values, estimates values of a first field respectively for multiple points on a substrate. Each of the sets of calibration values corresponds respectively to one of multiple actuators. The calibration values, in each of the sets of calibration values, define amounts of contribution provided by a respective one of the actuators to the first field for the points. The controller changes physical states of the actuators based on the estimated values of the first field of the points to provide a predetermined temperature distribution profile across the electrostatic chuck.