Substrate Support Heater Zoning for Wafer Temperature Uniformity
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Solution Overview
Problem
Existing substrate support assemblies in semiconductor manufacturing face challenges in 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 that enables both lateral and azimuthal tuning of heat transfer between an electrostatic chuck and a heater assembly, utilizing a plurality of independently controllable heaters in addition to main resistive heaters, to achieve precise temperature control across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional substrate supports with only edge to center temperature control are used, then the device complexity is reduced, but the temperature uniformity across the substrate deteriorates due to local hot and cold spots
Solution Approach 1:
The heater assembly is segmented into multiple independently controllable heating zones (first, second, third, and fourth heating zones) arranged in a grid pattern across the substrate support surface. This segmentation allows localized temperature control to compensate for hot and cold spots while maintaining overall temperature uniformity, resolving the contradiction between temperature uniformity and device complexity.
Solution Approach 2:
Each heating zone can be independently controlled to provide localized heating where needed, addressing the non-uniform heat transfer caused by the electrostatic chuck's heterogeneous structure. This local quality approach enables precise temperature control at specific locations without requiring complex global control systems.
2Ease of operation
If the electrostatic chuck has non-homogeneous construction with gas holes, lift pin holes, and offset electrodes, then the chucking functionality is improved, but the heat transfer uniformity between the chuck and substrate deteriorates
Solution Approach 1:
The heating zones are strategically positioned and independently controlled to compensate for the non-uniform heat transfer caused by gas holes, lift pin holes, and electrode offsets in the electrostatic chuck. Each zone can be adjusted to provide additional heating in areas where the chuck's heterogeneous structure creates cold spots, while maintaining appropriate heating in other areas.
Solution Approach 2:
Temperature sensors are positioned at multiple locations (including edge and center regions) to monitor the actual temperature distribution across the substrate. This feedback information is used to dynamically adjust the power supplied to each heating zone, compensating for the heat transfer non-uniformity introduced by the electrostatic chuck's construction features.
3Ease of manufacture
If chamber asymmetries in temperature, flow conductance, and RF fields are present, then the processing chamber design is simplified, but the critical dimension variation across the substrate increases
Solution Approach 1:
The system dynamically changes the heating parameters (power levels) of different heating zones based on real-time temperature feedback and process conditions. This allows compensation for chamber asymmetries in temperature, flow conductance, and RF fields by adjusting local heating to maintain uniform substrate temperature, thereby reducing critical dimension variation without requiring complex chamber redesign.
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 effectively eliminates local hot and cold spots, achieves critical dimension (CD) variation correction, and maintains temperature uniformity across the substrate to less than ±0.3 degrees Celsius, enhancing processing consistency and precision.
Implementation Method 1
one or more main resistive heaters disposed in the substrate support; and a plurality of heaters in column with the main resistive heaters and disposed in the substrate support
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 heater assembly. The substrate support assembly comprises an upper surface and a lower surface; one or more main resistive heaters disposed in the substrate support; and a plurality of heaters in column with the main resistive heaters and disposed in the substrate support. A quantity of the heaters is an order of magnitude greater than a quantity of the main resistive heaters and the heaters are independently controllable relative to each other as well as the main resistive heater.