Inverted Lens Master Fabrication for Uniform Thickness
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Solution Overview
Problem
The jet dispense process for creating lens masters in microelectronic imager modules faces challenges such as non-uniform lens thickness, low throughput, residual polymer volume, difficulty in controlling polymer dispense volume, and accuracy issues in lens alignment, leading to potential image quality problems and increased production complexity.
Innovation Solution
An inverted method of forming lens masters using a mask on a glass substrate with patterned aperture openings and alignment marks, where concave or convex lens pin molds are used to fill and cure jet-dispense fluid within holes, resulting in more uniform lens elements and reduced residual polymer, improving adhesion and alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If jet dispense process is used to create lens masters, then lens elements can be formed, but uniform thickness of lens elements cannot be maintained due to bonding variability and placement accuracy issues
Solution Approach 1:
The patent inverts the traditional jet dispense process by placing the lens pin mold on the substrate first, then jet dispensing polymer into the mold cavities. This inversion ensures that polymer is contained within defined boundaries from the start, eliminating the need for post-dispense containment and ensuring uniform thickness without complex bonding operations.
Solution Approach 2:
The lens pin mold is prepared in advance with precise cavity dimensions and is positioned on the substrate before polymer dispensing. This preliminary preparation of the mold structure ensures that when polymer is dispensed, it is immediately contained within boundaries that guarantee uniform thickness, eliminating thickness variation issues.
2Ease of manufacture
If traditional jet dispense process is used, then lens masters can be fabricated, but residual polymer volume remains outside lens areas causing alignment problems
Solution Approach 1:
The patent extracts the harmful residual polymer from the process by using a mold structure that contains polymer strictly within lens boundaries. The mold cavities act as physical barriers that prevent polymer from spreading outside designated lens areas, thereby eliminating residual polymer issues that cause alignment problems.
3Ease of manufacture
If jet dispense process is used, then lens masters can be created, but polymer dispense volume control is difficult leading to inconsistencies
Solution Approach 1:
The mold cavities are prepared in advance with precise dimensions and volumes. This preliminary preparation means that the container for the polymer is pre-defined with exact specifications, making it easy to control the amount of polymer dispensed simply by filling to a defined level, thereby improving volume control consistency.
4Productivity
If conventional lens master fabrication is used, then lens elements can be produced, but alignment accuracy between lens wafer and imager wafer deteriorates
Solution Approach 1:
The patent introduces alignment marks as an intermediary feature between the lens pin mold and the substrate. These marks provide a reference system that enables precise alignment between the lens wafer and imager wafer during assembly, thereby improving alignment accuracy without sacrificing production efficiency.
5Ease of manufacture
If jet dispense process is used, then lens masters can be fabricated, but throughput remains low due to sequential processing requirements
Solution Approach 1:
The patent merges multiple operations into a single integrated process: the lens pin mold serves simultaneously as the containment structure for polymer dispensing, the curing template, and the alignment reference (via integrated alignment marks). This consolidation eliminates sequential processing steps and enables higher throughput while maintaining ease of manufacture.
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 inverted method ensures uniform lens thickness, reduces residual polymer and voiding, enhances adhesion, and simplifies the alignment process, leading to improved image quality and increased production efficiency by minimizing chipping and delamination during the dicing stage.
Implementation Method 1
The jet-dispense fluid is cured, for example, by ultraviolet irradiation
Data Source
AI summary
A method and apparatus used for forming a lens master for forming lenses on a wafer. The method includes using an inverted lens pin mold in conjunction with a dispense method to create both concave and convex lens masters for making lens stamps containing lens-shaped cavities. The lens-shaped cavities are used to imprint a plurality of lenses into a curable material.