Wafer Temperature Control Pedestal with Segmented Heating and Cooling
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Solution Overview
Problem
Conventional semiconductor processing chamber pedestals with embedded heaters suffer from temperature control issues due to hot and cold spots, leading to substrate warpage and reduced planarity, which affects the quality of films deposited during integrated circuit fabrication.
Innovation Solution
A heated support pedestal with a conductive substrate support, a resistive heater encapsulated within, and an active cooling system that includes a hollow shaft with a cooling channel assembly, allowing for precise temperature control through a heat control gap between the heating element and the cooling channel, ensuring uniform heating and minimal thermal gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional pedestal with an embedded heater is used, then the substrate can be heated, but hot and cold spots are created affecting temperature uniformity
Solution Approach 1:
The heating system is segmented into multiple independent resistive heating elements positioned at different locations (center and periphery) on the pedestal. This segmentation allows independent control of heating zones to eliminate hot and cold spots, achieving uniform temperature distribution across the substrate surface.
Solution Approach 2:
Different regions of the pedestal are equipped with different heating elements tailored to local thermal requirements. The center heating element addresses the central zone while peripheral heating elements address edge zones, creating locally optimized heating that results in overall temperature uniformity.
2Temperature
If the pedestal is heated, then the substrate temperature is elevated for processing, but the pedestal bows upwards causing substrate warpage
Solution Approach 1:
The cooling channels are strategically positioned and configured to create a counterbalancing thermal field that offsets the upward bowing force. By removing heat from specific regions, the thermal expansion is balanced, maintaining pedestal planarity even at elevated substrate temperatures.
Solution Approach 2:
The system dynamically adjusts heating and cooling parameters to maintain thermal balance. By changing the temperature parameters of different zones independently, the pedestal maintains its flat shape while the substrate achieves the required processing temperature.
3Temperature
If active cooling is added to control temperature, then temperature control is improved, but the device complexity increases
Solution Approach 1:
The heating and cooling functions are merged into a single integrated pedestal structure. The resistive heating elements and cooling channels coexist within the same pedestal body, allowing simultaneous thermal management in one unified component rather than separate systems.
Solution Approach 2:
The pedestal is designed as a multi-functional component that simultaneously provides mechanical support, heating, and cooling capabilities. This universal design consolidates multiple functions into one structure, achieving wide temperature control range without proportionally increasing overall device complexity.
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 provides active temperature control over a wide range, maintaining substrate planarity with a maximum deflection of less than 5 thousandths of an inch, effectively addressing the temperature control challenges and ensuring high-quality film deposition.
Implementation Method 1
a resistive heater encapsulated within the substrate support
Implementation Method 2
a cooling channel assembly encircling the hollow core and disposed within the shaft body for removing heat from the pedestal via an internal cooling path
Implementation Method 3
removing heat from the pedestal via an internal cooling path
Implementation Method 4
the substrate support has a heat control gap positioned between the heating element and the ring-shaped cooling channel
Data Source
AI summary
Embodiments of the invention generally relate to a semiconductor processing chamber and, more specifically, a heated support pedestal for a semiconductor processing chamber. In one embodiment, a pedestal for a semiconductor processing chamber is provided. The pedestal comprises a substrate support comprising a conductive material and having a support surface for receiving a substrate, a resistive heater encapsulated within the substrate support, a hollow shaft coupled to the substrate support at a first end and a mating interface at an opposing end, the hollow shaft comprising a shaft body having a hollow core, and a cooling channel assembly encircling the hollow core and disposed within the shaft body for removing heat from the pedestal via an internal cooling path, wherein the substrate support has a heat control gap positioned between the heating element and the ring-shaped cooling channel.