Ceramic Wafer Support Geometry for Edge Cooling Uniformity
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Solution Overview
Problem
The outer circumferential portion of a wafer in semiconductor manufacturing apparatus does not receive sufficient cooling during plasma processing, leading to localized high temperatures due to insufficient thermal conduction from the cooling plate.
Innovation Solution
The member for semiconductor manufacturing apparatus features a ceramic plate with a circular wafer placement surface and an annular focus ring placement surface connected by a lateral surface of a circular truncated cone, increasing the number of thermal paths from the outer circumferential portion of the wafer to the cooling plate, thereby enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the lateral surface of the connection part is perpendicular to the wafer placement surface, then the structure is simple and easy to manufacture, but the number of thermal paths from the outer circumferential portion of the wafer to the cooling plate is insufficient, resulting in inadequate cooling
Solution Approach 1:
The connection part employs a tapered cylindrical shape with a lateral surface that is inclined relative to the wafer placement surface, forming an angle between 45° and 75°. This curved/tapered geometry increases the contact area between the wafer's outer circumferential portion and the cooling plate, thereby enhancing thermal conduction and cooling efficiency without significantly complicating the manufacturing process.
2Temperature
If the diameter of the wafer placement surface is smaller than the diameter of the wafer, then the wafer can be properly positioned, but the outer circumferential portion of the wafer is likely to have high temperature due to insufficient cooling
Solution Approach 1:
The tapered cylindrical connection part with an inclined lateral surface creates an expanded cooling area that extends outward to accommodate the wafer's outer circumferential portion. This geometric design allows the cooling plate to effectively cool regions beyond the wafer placement surface diameter, ensuring uniform temperature distribution across the entire wafer including its outer edges.
3Temperature
If the angle of the lateral surface with respect to the focus ring placement surface is greater than 70°, then the structure is simpler, but the number of thermal paths is not sufficiently increased
Solution Approach 1:
The invention specifies that the lateral surface of the connection part forms an angle between 45° and 75° with respect to the focus ring placement surface. This optimized angular range maximizes the number of thermal paths from the wafer's outer circumferential portion to the cooling plate while maintaining manufacturing feasibility. The specific angle parameter ensures sufficient thermal conduction enhancement without excessive structural 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 design improves the cooling capability of the outer circumferential portion of the wafer, preventing excessive heating and maintaining temperature uniformity across the wafer, while also preventing excessive cooling of the inner circumferential portion of the focus ring.
Implementation Method 1
the wafer receives heat input from plasma, but the wafer is cooled by the cooling plate
Data Source
AI summary
A member for semiconductor manufacturing apparatus includes a ceramic plate including a horizontal and circular wafer placement surface, and a horizontal and annular focus ring placement surface provided on an outer circumference of the wafer placement surface at a position lower than the wafer placement surface by one step, and a connection part that connects the wafer placement surface and the focus ring placement surface; and a cooling plate provided on a lower surface of the ceramic plate, wherein the connection part has a lateral surface of a circular truncated cone with a diameter that increases from the wafer placement surface to the focus ring placement surface, and the diameter of the upper surface of the circular truncated cone matches the outer diameter of the wafer placement surface, and the diameter of the lower surface of the circular truncated cone matches the inner diameter of the focus ring placement surface.