Stiffness Mismatch Joining via Intermediary Plate
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Solution Overview
Problem
Adhesive bonding between components with different stiffnesses leads to deformations, particularly in wafer chucks with lower stiffness, causing inaccurate positioning and potential failure in microlithography due to stress transfer from adhesive shrinkage.
Innovation Solution
Bonding a plate-shaped body with lower stiffness to the component with higher stiffness using an adhesive, then correcting deformations by smoothing the surface and using methods like wringing, anodic bonding, or fusion bonding without a joining agent to minimize additional deformations, allowing the plate-shaped body to absorb and correct mechanical stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive bonding is used to join components with different stiffnesses, then the components can be connected, but deformations occur due to adhesive shrinkage transferring to the less stiff component
Solution Approach 1:
A plate-shaped body made of glass or glass-ceramic material is introduced as an intermediary component between the wafer table and wafer chuck. This intermediate plate absorbs the deformations caused by adhesive shrinkage through its own flexibility, preventing stress transfer to the less stiff component and maintaining dimensional stability of the assembled structure
Solution Approach 2:
The stiffness parameter of the intermediate plate is specifically selected to be lower than that of the wafer table but higher than or comparable to the wafer chuck. This parameter optimization allows the plate to serve as a deformation buffer while maintaining structural integrity, resolving the contradiction between joining strength and dimensional stability
2Weight of moving object
If the wafer chuck is made from light material to reduce inertia, then movement performance improves, but stiffness decreases leading to greater deformation susceptibility
Solution Approach 1:
The system employs a composite structure combining the light-weight wafer chuck (made from materials like Zerodur® or cordierite) with a rigid plate-shaped body (glass or glass-ceramic) and adhesive bonding. This composite approach allows the wafer chuck to maintain low weight for reduced inertia while the stiffer plate material compensates for the chuck's lower stiffness, preventing excessive deformation
3Strength
If adhesive shrinkage is allowed to occur, then bonding is achieved, but stresses and deformations are generated in the components
Solution Approach 1:
The plate-shaped body acts as a stress-absorbing intermediary that takes up the shrinkage stresses generated during adhesive bonding. By positioning this plate between the wafer table and wafer chuck, the bonding process can proceed with full adhesive shrinkage while the plate protects the final assembly from stress-induced deformations
Solution Approach 2:
The adhesive shrinkage, which would normally be harmful causing deformations, is converted into a beneficial effect by allowing it to occur in the intermediate plate rather than in the final assembly. The plate's deformation during bonding actually protects the wafer chuck and wafer table from stress, transforming the harmful shrinkage into a protective mechanism
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 approach reduces deformations in the less stiff component, ensuring low deformation joining and maintaining dimensional stability, which is critical for precise positioning in microlithography applications.
Implementation Method 1
Wringing is a connection of two materials in which the surfaces brought together are held only by forces of molecular attraction
Implementation Method 2
the adhesive used cures, as a result of which the adhesive is subject to shrinkage
Implementation Method 3
the plate-shaped body to absorb and correct mechanical stresses
Implementation Method 4
Wringing is a connection of two materials in which the surfaces brought together are held only by forces of molecular attraction
Implementation Method 5
anodic bonding of silicon carbide to glass to fabricate a MEMS device
Implementation Method 6
bonding two components by 'fusion bonding' to form a bonded structure
Data Source
Figure 1~3b
AI summary
The invention relates to a method for connecting two components (1, 2) having different stiffnesses (E1, E2), comprising: bonding a plate-shaped body (3) onto the component (1) having greater stiffness (E1), the bonding being preferably performed using a joining agent, in particular an adhesive, correcting deformations produced by the bonding on the plate-shaped body (3), and connecting the component (2) having the lower stiffness (E2) to the plate- shaped body (3), in particular by wringing, by anodic bonding or by fusion bonding. The invention also relates to a composite structure (5), which has been produced according to the method and which can serve, for example, as a holding device for a wafer (6). Moreover, the first component (1) can serve as a carrier for the second component (2), e.g. if the latter is embodied as an EUV mirror.