Tunable Electrostatic Chuck Support for Wafer Temperature Uniformity
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Solution Overview
Problem
Existing substrate support assemblies in semiconductor manufacturing struggle with achieving uniform temperature control across substrates due to chamber asymmetries and non-homogeneous construction of electrostatic chucks, leading to local hot and cold spots and non-uniform processing results.
Innovation Solution
A substrate support assembly with a body containing tunable heaters and an electrical controller that allows independent control of each heater, enabling both lateral and azimuthal temperature control. This assembly includes main resistive heaters and spatially tunable heaters, with a tuning heater controller to adjust the power to each heater individually.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional substrate supports with only edge to center temperature control are used, then the device is simple, but local hot and cold spots within the electrostatic chuck cannot be compensated for, resulting in non-uniform temperature distribution
Solution Approach 1:
The heater assembly is divided into multiple independently controllable heater zones (first, second, third, and fourth heater zones) arranged in a grid pattern across the substrate support surface. Each zone can be controlled separately to compensate for local hot and cold spots, transforming a single uniform temperature control system into a segmented, locally adjustable system that achieves superior temperature uniformity.
Solution Approach 2:
Each heater zone is independently controllable with individual power levels, allowing local temperature adjustments to compensate for non-uniform heat transfer in different regions of the electrostatic chuck. This enables precise local quality control where each zone can be optimized for its specific thermal conditions, eliminating hot and cold spots through localized heating adjustments.
2Temperature
If the electrostatic chuck has non-homogeneous construction with gas holes, lift pin holes, and offset electrodes, then the chuck structure is functional, but uniformity of heat transfer between the chuck and substrate is complicated, resulting in local hot and cold spots
Solution Approach 1:
The heater zones are strategically positioned and independently controlled to compensate for the non-homogeneous chuck structure. By providing local heating control in each zone, the system can offset the thermal effects of gas holes, lift pin holes, and electrode offsets, achieving uniform heat transfer to the substrate despite the complex chuck construction.
Solution Approach 2:
The system uses temperature sensors to monitor the substrate surface temperature and feeds this information back to the controller, which adjusts the power to each heater zone accordingly. This closed-loop feedback mechanism compensates for the non-uniform heat transfer caused by the chuck's non-homogeneous structure, maintaining uniform substrate temperature.
3Manufacturing precision
If individually controllable heaters are implemented across the substrate support surface, then temperature uniformity is improved, but the device complexity increases
Solution Approach 1:
The substrate support surface is divided into a finite number of heater zones (four zones in the described embodiment) arranged in a grid pattern. This segmentation provides sufficient temperature control capability to achieve uniform critical dimensions without requiring excessive complexity, as the zones are numbered and controlled in a systematic sequence.
Solution Approach 2:
The heater assembly serves multiple functions: it provides overall substrate heating, enables local temperature compensation, and maintains temperature uniformity across the substrate surface. The same heater zone infrastructure achieves all these objectives simultaneously, reducing the need for additional separate 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
The solution achieves precise control of the substrate temperature, reducing temperature variations to less than ±0.3 degrees Celsius, which improves the uniformity of processing results and corrects critical dimension (CD) variations across the substrate.
Implementation Method 1
one or more main resistive heaters disposed in the body, a plurality of spatially tunable heaters disposed in the body
Data Source
AI summary
Implementations described herein provide a substrate support assembly which enables both lateral and azimuthal tuning of the heat transfer between an electrostatic chuck and a heating assembly. The substrate support assembly comprises a body having a substrate support surface and a lower surface, one or more main resistive heaters disposed in the body, a plurality of spatially tunable heaters disposed in the body, and a spatially tunable heater controller coupled to the plurality of spatially tunable heaters, the spatially tunable heater controller configured to independently control an output one of the plurality of spatially tunable heaters relative to another of the plurality of spatially tunable heaters.