Microlens Profiling via Selective Chemical Etching
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Solution Overview
Problem
Manufacturing defects in microlenses of solid-state imagers, such as non-uniform or blocked photosensors, are prevalent due to the small size of the lenses, leading to reduced fabrication yields and increased costs.
Innovation Solution
Localized accelerated selective chemical etching using an electron beam and a halogen-containing compound in a vacuum chamber, allowing for precise etching and profiling of microlens surfaces to diagnose and address defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the size of microlenses is reduced to increase pixel cell density, then the number of photosensors per unit area increases, but manufacturing defects increase and fabrication yields decrease
Solution Approach 1:
The patent segments the microlens inspection process into multiple sequential etching steps, allowing different regions and depths of the microlens to be analyzed separately. This enables detailed defect characterization without requiring analysis of the entire microlens array simultaneously, thereby improving manufacturing precision while accommodating high pixel cell density
Solution Approach 2:
The patent introduces a temporal dimension to the inspection process by performing sequential etching at different depths and stages. Instead of attempting to analyze all microlenses at once in a single step, the inspection is divided into multiple time-based stages, allowing progressive revelation and analysis of defects at different levels, thus resolving the contradiction between high density and defect detection precision
2Ease of manufacture
If conventional etching methods are used on microlenses, then the process is simple and quick, but the etching is not selective enough to diagnose specific defect locations and depths
Solution Approach 1:
The etching process is segmented into multiple selective steps, each targeting specific depth regions or material layers of the microlens. This segmentation maintains relative process simplicity while dramatically improving defect location precision by isolating defects to specific etching stages and analyzing them separately
Solution Approach 2:
The patent applies preliminary selective etching steps that prepare and reveal specific regions of interest before final analysis. By performing preliminary actions to expose particular defect locations and depths in controlled stages, the method achieves high measurement precision without requiring overly complex final inspection procedures
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 enhances defect analysis and fabrication yields by enabling selective and sequential etching of microlens layers, improving the uniformity and functionality of solid-state imager lenses.
Implementation Method 1
exciting the halogen atoms with an electron beam to form chemical radicals
Implementation Method 2
electrons from the primary beam, electrons scattered from the lens surface, as well as secondary electrons from the lens surface may all cause the formation of halogen radicals by dissociating the individual atoms of the halogen containing layer
Implementation Method 3
The radicals may selectively, or non-selectively, etch portions of the lens surface
Implementation Method 4
the etch products may be removed from the surface of the lens by a vacuum system pump
Data Source
AI summary
Methods may operate to position a sample within a processing chamber and operate on a surface of the sample. Further activities may include creating a layer of reactive material in proximity with the surface, and exciting a portion of the layer of reactive material in proximity with the surface to form chemical radicals. Additional activities may include removing a portion of the material in proximity to the excited portion of the surface to a predetermined level, and continuing the creating, exciting and removing actions until at least one of a plurality of stop criteria occurs.