Patterned Wafer Microruler for Laser Coating Overspray
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for overspray screening of anti-reflective (AR) and highly reflective (HR) coatings in semiconductor laser manufacturing are neither practical nor cost-effective, relying on post-deposition visual inspection under a high-powered microscope, which delays process corrections and increases costs due to the need for separate facilities for deposition and inspection.
Innovation Solution
A microruler is patterned on the surface of a laser bar with graduation markings aligned with the cleaving line, allowing for quantitative measurement of overspray, enabling bar-level overspray screening using a low-power microscope, providing instant feedback and reducing material and logistic costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If post-deposition visual inspection under high-powered microscope is used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
A microruler structure with graduation markings is introduced as an intermediary reference object on the wafer surface. This microruler serves as a physical mediator that enables direct visual measurement of overspray distance without requiring complex microscope systems, thus maintaining measurement precision while reducing inspection system complexity
Solution Approach 2:
The microruler creates a scaled reference copy of measurement units directly on the wafer surface. By patterning known dimensional features (graduation markings) onto the wafer, the system enables quantitative measurement through simple visual comparison rather than requiring complex optical measurement systems
2Manufacturing precision
If separate facilities for deposition and inspection are used, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The microruler reference structure is integrated directly onto the wafer surface during the same fabrication process, merging the measurement reference with the device structure. This integration allows inspection to be performed at the same facility where deposition occurs, eliminating the need for separate facilities and reducing time loss while maintaining precision through the built-in reference markings
Solution Approach 2:
The microruler with graduation markings is prepared in advance on the wafer surface before the deposition process. This preliminary preparation of the measurement reference enables immediate post-deposition inspection and rapid process correction without requiring additional setup time or separate facility transitions
3Measurement precision
If conventional visual inspection methods are used, then measurement accuracy is improved, but productivity decreases
Solution Approach 1:
The microruler structure enables the wafer itself to provide the measurement reference needed for inspection. Each wafer carries its own built-in microruler with graduation markings, allowing operators to perform self-contained measurements without requiring complex external measurement equipment or multiple inspection stations, thus maintaining accuracy while improving throughput
Data Source
AI summary
In some implementations, a microruler is patterned on a surface of a wafer to enable visual overspray screening and/or quantitative measurement. For example, a laser bar cleaved from a wafer may comprise multiple laser devices that each include a first facet and a second facet, an anti-reflective (AR) coating applied to the first facet, and a highly reflective (HR) coating applied to the second facet. Furthermore, a set of microrulers may be patterned on a surface of the laser bar, where each microruler in the set of microrulers is aligned with a bar cleaving line where the laser bar was cleaved from the wafer, and each microruler has multiple graduation markings that each represent a respective distance from the bar cleaving line such that the graduation markings can be used to quantitatively measure an overspray of the AR coating or the HR coating relative to the bar cleaving line.