Release Agent Patterning for Anti-Reflection Coating on Cavities
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Solution Overview
Problem
Current methods for forming anti-reflection coatings on optical window wafers in wafer level packaging are cumbersome, requiring expensive capital equipment, precise polishing, and messy lift-off processes, which are challenging to implement, especially on recessed surfaces and in the semiconductor industry due to cleanliness and particle control issues.
Innovation Solution
A method involving a release agent is applied only to the top surfaces of the wafer, allowing for blanket coating and subsequent selective removal, eliminating the need for shadow masks, polishing equipment, and capital-intensive processes like photolithography, by using a thin, water-soluble release layer that is easily removed, leaving the anti-reflection coating on the cavity bottoms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shadow mask is used to pattern anti-reflection coating, then coating pattern can be formed, but alignment tolerance and edge sharpness are limited, and additional alignment tooling and mask costs are required
Solution Approach 1:
The invention extracts the pattern definition function from complex alignment tooling and shadow masks, embedding it directly into the release agent structure itself. The release agent contains embedded features that define the coating pattern without requiring external alignment tools or separate masking steps.
Solution Approach 2:
The release agent serves multiple functions simultaneously: it acts as a release layer for the anti-reflection coating, contains the pattern definition through embedded features, and eliminates the need for separate alignment tooling and shadow masks. This multi-functionality reduces both complexity and cost.
2Manufacturing precision
If photolithographic lift-off method is used, then coating pattern can be formed, but expensive capital equipment is required and the process is messy with particle control issues
Solution Approach 1:
The invention replaces expensive, complex photolithographic equipment with a simple, disposable release agent structure. The release agent is applied, patterned through its embedded features, and then easily removed without requiring capital equipment or creating messiness.
Solution Approach 2:
The invention substitutes the mechanical photolithographic system with a chemical release agent approach. Instead of using UV light and photoresist, the pattern is defined by the physical structure of the release agent itself, which is then removed through simple cleaning processes.
3Manufacturing precision
If polish off method is used to remove upper surface, then coating pattern can be formed on recessed surfaces, but precision optical polishing equipment and skilled operators are required
Solution Approach 1:
Instead of removing material to reveal the pattern (polishing off), the invention applies the pattern definition directly to the surface where the coating will be deposited. The release agent is placed on the top surface, and the anti-reflection coating is deposited only where the release agent is present, eliminating the need for subsequent material removal.
Solution Approach 2:
The invention performs the pattern definition action before the coating deposition. The release agent with embedded pattern features is applied to the surface in advance, and the anti-reflection coating is then deposited only in the desired areas through selective adhesion, eliminating the need for post-deposition polishing.
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 simplifies the process, reduces equipment costs significantly, and ensures precise coating without the need for expensive machinery, enhancing cleanliness and particle control, making high-volume production more efficient and cost-effective.
Implementation Method 1
contacting top surfaces of the sidewalls with the portions of the contacted release agent being transferred to the top surfaces of the substrate
Implementation Method 2
exposing the surface of the intermediate structure to the material to blanket coat the material on both the release agent disposed on the top surface of the substrate and the bottom portions of the cavities
Implementation Method 3
exposing the intermediate structure having the coated release agent and the bottom portions to a process to selectively remove the release agent together with the coating material thereon from the top surface of the substrate while leaving the coating material on the bottom portions of the cavities
Data Source
Figure 1A~1C
Figure 1D~1E
AI summary
A method for forming a coating of material on selected portions of a surface of a substrate having a plurality of cavities (11) includes: providing a structure (16) having a release agent (18) thereon; contacting a top surface (17) of the wafer (10) with the release agent to transfer portions of the release agent to the top surface of the wafer while bottom portions of the cavities remain spaced from the release agent to produce an intermediate structure (24); the release agent disposed on the top surface of the wafer and with the bottom portions of the cavities void of the release agent; exposing the intermediate structure to the material (27) to blanket coat the material on both the release agent and the bottom portions of the cavities; and selectively removing the release agent together with the coating material while leaving the coating material on the bottom portions of the cavities.