Wafer Placement Stage Clamping for Flat Focus-Ring Surfaces
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Solution Overview
Problem
The existing wafer placement devices often result in a wavy focus-ring placement surface due to height differences caused by fastening bolts, leading to incomplete attraction and difficulty in temperature adjustment of thick focus rings.
Innovation Solution
A wafer placement device design that includes a clamping member to press the focus-ring cooling plate flange against the mounting plate, avoiding direct fastening and maintaining a flat focus-ring placement surface, along with thermal resistance spacers for independent temperature control and a common seal ring for reduced space and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the focus-ring placement stage is fastened directly to the mounting plate using bolts, then the device structure is simple and easy to manufacture, but the focus-ring placement surface becomes wavy due to height differences around the bolts
Solution Approach 1:
The patent introduces a clamping member as an intermediary component between the focus-ring placement stage and the mounting plate. This clamping member includes a clamping surface that contacts the focus-ring cooling plate and a clamping portion that is fastened to the mounting plate, thereby mediating the connection and preventing direct bolt contact with the placement stage that would cause surface waviness.
Solution Approach 2:
The patent segments the fastening function from the placement stage structure by separating the clamping member into distinct components: the clamping surface for contacting the focus-ring cooling plate, the clamping portion for fastening to the mounting plate, and positioning protrusions for alignment. This segmentation allows each component to perform its specific function without interfering with the flatness of the placement surface.
2Manufacturing precision
If a clamping member is introduced to press the focus-ring cooling plate flange against the mounting plate, then the focus-ring placement surface remains flat, but the device structure becomes more complex
Solution Approach 1:
The clamping member is designed to perform multiple functions simultaneously: it provides clamping force through the clamping surface to maintain flatness, fastens to the mounting plate through the clamping portion, and ensures proper positioning through the positioning protrusions that fit into positioning holes. This multi-functionality reduces the need for separate components for each function.
Solution Approach 2:
The patent merges the clamping function, fastening function, and positioning function into a single integrated clamping member structure. The clamping surface, clamping portion, and positioning protrusions are combined in one component that fastens to the mounting plate and presses the focus-ring cooling plate, thereby simplifying the overall structure despite adding the clamping mechanism.
3Reliability
If multiple seal rings are used to seal between the cooling plates and mounting plate, then sealing performance is improved, but the device occupies more space and increases cost
Solution Approach 1:
The patent merges the sealing functions for the wafer cooling plate and focus-ring cooling plate into a single common seal ring. The seal ring is configured to seal between the wafer cooling plate and the mounting plate, and also to seal between the focus-ring cooling plate and the mounting plate, thereby combining multiple sealing functions into one component that reduces part count and 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 ensures a flat focus-ring placement surface for complete attraction and easy temperature adjustment, while maintaining independent temperature control of the wafer and focus ring, and reduces the need for multiple seal rings, enhancing sealing performance and cost-effectiveness.
Implementation Method 1
The wafer W is electrostatically attracted to the surface 514a when a DC voltage is applied to an electrostatic electrode that is incorporated in the wafer electrostatic chuck 514
Implementation Method 2
temperature of the wafer and temperature of the focus ring are controlled individually
Data Source
AI summary
A wafer placement device includes a wafer placement stage including a wafer electrostatic chuck and a wafer cooling plate, a focus-ring placement stage including a focus-ring electrostatic chuck and a focus-ring cooling plate, and a clamping member arranged around the focus-ring placement stage. The wafer placement stage, the focus-ring placement stage, and the clamping member are separate from one another. A pressing portion of the focus-ring cooling plate presses a wafer cooling plate flange against a mounting plate. The clamping member is fastened to the mounting plate with bolts in a state of pressing a flange against the mounting plate at its flange, thus fixing the wafer placement stage and the focus-ring placement stage to the mounting plate without directly fastening them to the mounting plate.