Electrostatic Chuck Heater Gas Distribution
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Solution Overview
Problem
Existing wafer-supporting tables face issues with reduced Johnsen-Rahbek force and non-uniform temperature distribution due to conductive films extending into gaps between the wafer and the ceramic base, affecting stable chucking and temperature uniformity during CVD processes.
Innovation Solution
An electrostatic-chuck heater with a disc-shaped ceramic base featuring a wafer-mounting surface with projections and a circular groove, along with a through-hole for gas supply, which prevents conductive films from adhering to the projections and ensures uniform gas flow, maintaining initial Johnsen-Rahbek force and improving temperature uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If purge gas is supplied through a through-hole in the ceramic base, then temperature uniformity is improved, but conductive films extend into gaps between the wafer and ceramic base, reducing Johnsen-Rahbek force
Solution Approach 1:
The ceramic base is segmented into multiple functional regions: a through-hole region for gas supply, an annular groove region for gas distribution, and a projection region for mechanical support. This segmentation allows each region to perform its specific function without interference, preventing conductive films from reaching the projections while maintaining temperature uniformity through proper gas flow.
Solution Approach 2:
The annular groove acts as an intermediary structure between the through-hole and the projections. It receives purge gas from the through-hole and distributes it uniformly across the wafer-back surface, mediating the flow to prevent conductive film deposition on projections while achieving temperature uniformity.
2Area of stationary object
If the through-hole extends to the outer peripheral side face of the ceramic base, then gas supply coverage is improved, but the flow becomes nonuniform, affecting temperature uniformity
Solution Approach 1:
The annular groove serves as an intermediary distribution channel that receives gas from the through-hole and redistributes it uniformly. This intermediary structure ensures both wide coverage (by extending along the peripheral wall) and uniform flow distribution (by releasing gas along the entire annular path).
Solution Approach 2:
The annular groove functions as a pneumatic distribution manifold, utilizing fluid dynamics principles to distribute the purge gas uniformly across the wafer-back surface. The groove geometry and gas flow rate are designed to achieve even pressure distribution, ensuring uniform temperature across the wafer.
3Area of stationary object
If the through-hole extends to the outer peripheral side face, then gas flow coverage increases, but conductive films may adhere to projection surfaces, reducing chucking stability
Solution Approach 1:
The ceramic base is segmented into functional zones where the annular groove creates a protective barrier zone. This segmentation ensures that gas flow and conductive film deposition are confined to the groove area, while the projections remain isolated and free from conductive film contamination, maintaining chucking stability.
Solution Approach 2:
The harmful effect of conductive film deposition is extracted and isolated to the annular groove region. By designing the groove to extend to the outer peripheral side face, the system takes out the potential contamination zone away from the critical projection surfaces, allowing wide gas flow coverage without compromising chucking reliability.
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 enables stable wafer chucking and improved temperature uniformity by preventing conductive films from adhering to the projections, maintaining the initial Johnsen-Rahbek force and reducing temperature variations, thus enhancing processing efficiency and production quality.
Implementation Method 1
a wafer-supporting table 110 having a function of attracting and holding the wafer W to the ceramic base 120 with a Johnsen-Rahbek force
Implementation Method 2
the ceramic base 120 includes an electrostatic electrode and a heating resistor
Data Source
AI summary
An electrostatic-chuck heater is of a Johnsen-Rahbek type and is used in a process of forming a conductive film on a wafer. The electrostatic-chuck heater includes a disc-shaped ceramic base including an electrostatic electrode and a heating resistor, and a hollow shaft attached to a side of the ceramic base that is opposite a side having a wafer-mounting surface. A through-hole extends in a peripheral wall of the hollow shaft from a lower end through to an area of the wafer-mounting surface that is on an inner side with respect to a circular groove. The through-hole allows gas to be supplied from the lower end of the hollow shaft into a below-wafer space enclosed by the wafer-mounting surface, an outermost projection group, and the wafer mounted on the wafer-mounting surface.