SLM Surface Correction via Adhesive Shrinkage Compensation
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Solution Overview
Problem
Existing methods for correcting the surface shape of reflective surface light modulators (SLMs) with small height and large lateral dimensions, such as chemical-mechanical polishing and compensation using piezo actuators or screws, are inadequate for achieving sufficient planarity, especially in microlithography applications, due to limitations in lateral resolution and heat dissipation.
Innovation Solution
A method involving the measurement of the SLM's surface shape after manufacture, followed by aligning the base part's surface with a correction shape that accounts for the shrinkage of a thermally or chemically shrinking connecting material, allowing the element to be bonded with precise surface alignment, where the correction shape's deviations are compensated post-curing, ensuring improved flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical-mechanical polishing (CMP) is used to planarize the SLM chip surface, then local flatness in small areas (up to a few 10 μm) is improved, but the method has little effect for larger dimensions in the mm and cm range
Solution Approach 1:
The invention applies preliminary action by pre-forming a correction shape on the base part that anticipates and compensates for the adhesive shrinkage effects. The correction shape is calculated based on expected deformation patterns, allowing the SLM chip surface to be planarized after adhesive curing without requiring extensive post-processing for large-area flatness correction.
2Manufacturing precision
If an array of piezo actuators or screws is used to compensate for non-planar shape, then surface flatness can be improved, but the device complexity and cost increase significantly
Solution Approach 1:
The invention extracts the flatness correction function from complex active compensation systems (piezo actuators, screws) and transfers it to a passive geometric correction shape integrated into the base part. This eliminates the need for expensive, complex actuator arrays while achieving the same surface flatness improvement through pre-calculated geometric compensation for adhesive shrinkage.
3Manufacturing precision
If an array of piezo actuators is used for surface correction, then flatness can be adjusted, but heat dissipation capability is greatly reduced
Solution Approach 1:
The invention removes the heat-dissipating structures (piezo actuators) from the system and replaces them with a passive correction shape that provides flatness adjustment without interfering with thermal management. The base part's correction shape achieves the same surface planarity function without blocking heat conduction paths from the SLM chip.
4Strength
If the SLM chip is bonded using adhesive with thermal or chemical shrinkage, then strong mechanical connection is achieved, but uncontrollable surface shape changes occur due to capillary forces and shrinkage
Solution Approach 1:
The invention applies preliminary anti-action by pre-forming a correction shape on the base part that counteracts the expected adhesive shrinkage effects. The correction shape is calculated to produce opposite deformations that compensate for the shrinkage-induced surface changes, transforming an uncontrollable process into a predictable and correctable one while maintaining strong bond strength.
5Stability of the object's composition
If filling structures are added to balance metallization density, then average density distribution is improved, but surface flatness is degraded due to additional hills and valleys
Solution Approach 1:
The invention applies preliminary action by pre-calculating and pre-forming a correction shape that compensates for the surface deformations caused by filling structures. The correction shape anticipates the hills and valleys created by metallization density balancing and provides geometric compensation, allowing both density stability and surface flatness to be achieved.
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 method effectively corrects surface deviations down to fractions of wavelengths (below 100 nm) and achieves planarity improvements up to several micrometers, reducing the need for complex actuator systems and heat dissipation issues, while being insensitive to adhesive thickness and distribution.
Implementation Method 1
thermally or chemically shrinking connecting material
Implementation Method 2
thermally or chemically shrinking connecting material
Data Source
Figure 1~3
AI summary
The present invention relates to a method for correcting the surface form of an element which is connected to a base part by means of a thermally or chemically shrinking connecting material and whose height is very much smaller than its lateral dimensions, in particular in the production of SLM assemblies, comprising the following steps: Measuring the current surface form of the element after the production thereof in order to detect deviations from the desired surface form, providing the base part surface with a negative correction form with respect to the deviations from the desired surface form of the element, applying the connecting material to the base part surface or the underside of the element, and joining together the element and the base part whilst aligning them in accordance with the current surface form and the correction form, curing the connecting material, which shrinks thermally or chemically in such a way that the deviations of the current surface form of the element are compensated for in order to obtain the desired surface form.