Segmented Sample Stage Heaters for Plasma Wafer Temperature Control
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Solution Overview
Problem
Conventional plasma processing apparatuses face challenges in achieving uniform temperature control across the circumference of semiconductor wafers, leading to variations in processing results and potential electrostatic damage due to increased RF power leakage, especially as wafer diameters increase.
Innovation Solution
A plasma processing apparatus with a sample stage featuring heaters divided radially and circumferentially, connected in series with DC power supplies, allowing for precise control of heat distribution and reducing temperature variations through a control unit that adjusts the amounts of heat generated by these heaters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single heater is used for the sample stage, then the structure is simple, but temperature uniformity across the wafer circumference cannot be controlled
Solution Approach 1:
The heater is divided into multiple independent heating regions (first heating region, second heating region, third heating region) arranged circumferentially around the sample stage. Each region can be controlled independently to achieve uniform temperature distribution across the wafer circumference, resolving the contradiction between temperature uniformity and structural simplicity.
Solution Approach 2:
Different heating regions are assigned different heating characteristics and control parameters to address local temperature variations at different circumferential positions. This allows precise local temperature control to compensate for non-uniform heat distribution, achieving overall temperature uniformity while maintaining a relatively simple segmented heater structure.
2Productivity
If RF power is increased to improve plasma processing efficiency, then productivity increases, but electrostatic damage risk increases due to RF power leakage
Solution Approach 1:
A shield structure is introduced as an intermediary between the plasma processing environment and the sample stage. This shield acts as a barrier to block or reduce RF power leakage and electrostatic interference reaching the sample, allowing high RF power to be used for improved processing efficiency while protecting against electrostatic damage.
3Productivity
If wafer diameter is increased to improve processing capacity, then productivity increases, but temperature control uniformity deteriorates
Solution Approach 1:
The heater is segmented into multiple circumferential heating regions that can be independently controlled. This segmentation allows the temperature profile to be optimized for larger wafer diameters by adjusting the power distribution across different radial and circumferential zones, maintaining temperature uniformity even as wafer size increases to improve processing capacity.
Solution Approach 2:
The heating control is extended from simple radial control to two-dimensional circumferential and radial control. By adding circumferential segmentation to the heating zones, the system can compensate for edge effects and non-uniform heat distribution across larger wafer areas, maintaining temperature uniformity while accommodating increased wafer diameters for higher productivity.
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 configuration enhances the accuracy of wafer processing by reducing temperature variations across the wafer's circumference, improving processing yield and preventing electrostatic damage by minimizing RF power leakage.
Implementation Method 1
a heater connected to this sample mounting stage and disposed below this stage. The temperature of the ceramic disk and the temperature of the wafer mounted on top of the disk are made appropriate for processing by adjusting the amount of heat generated by the heater.
Implementation Method 2
a plasma processing apparatus for processing a wafer disposed within a processing chamber inside a vacuum vessel with a plasma generated within the processing chamber
Data Source
AI summary
There is disclosed a plasma processing apparatus for processing a wafer put on a sample stage disposed in a processing chamber within a vacuum vessel by the use of a plasma generated in the processing chamber after mounting the wafer on the sample stage. The apparatus has heaters in areas of the interior of the sample stage which are divided radially and circumferentially. At least those of the heaters which are arranged in the areas located in the radially outer position include circumferentially arranged heater portions that are connected in series. The amounts of heat generated by these circumferentially arranged heater portions are adjusted.