Glass Wafer Inspection

• Application-Specific Designs: Dark Field brightfield and darkfield Solid State Laser Reflection (SSLR) scanners, designed specifically for your unique application deliver unmatched defect detection to 1µm while generating real time alarms and alerts for defects and measurements which are outside the LCL and UCL.
• Superior detection (to 1μm): The ONLY system that uses lasers and cameras together (SSLR). Light interacts with the defect two times for enhanced detection. Darkfield and brightfield designs.
• High Speed: 1 – 2 seconds per wafer.
• Compact design easily integrated with automation: This is the simplest system to install with a small installation envelope and does not require shrouding. Scanners can be easily integrated with a wafer cassette and production line.
• Self-Aligning, no maintenance system: SSLR is the only self-aligning, production-worthy system in the world; SSLR never needs to be tuned. No more missed defects and false hits.
• First Surface inspection: Detects defects on the first surface and ignores defects on the second surface.

• Surface cleanliness measurement: As 30% – 70% of all coating defects are due to poorly cleaned surfaces, SSLR technology measures the cleanliness of the surface and generates a Clean Number which is used to alarm/reject parts which are outside the critical quality control limits.
• Curved glass inspection: Unique self-aligning SSLR scanner delivers extraordinary inspection of curved surfaces from 6mm to infinite radii of curvature.
• Zone inspection: Wafer zones may be defined, each with its own inspection criteria.
• Information, not just data: Maximize information with customer-specific trends and reports. Customized for each installation, trends and reports are generated from the integrated SQL Server. This ensures that maximum information is delivered by the system, not just data and images.
• Modular design – simple upgrade path: Dark Field systems are completely modular. This means that scanner design and electronic processing modules are optimized for each application. Optics and processing modules can be specified and upgraded independently.

Uncoated Glass Wafers – Quality Challenges

• Wafers must be defect-free. Wafers need to be sorted into G/NG classes so rejected wafers can be removed from the production line and returned to the vendor for credit.
• Manual inspection is time consuming, expensive, subjective, and inexact; critical defects cannot be reliably detected. Each wafer handling step adds defects, thereby reducing yield.
• Unconventional shapes (non-circular) increase the manual inspection challenge.
• Conventional camera technologies do not deliver consistent high-speed inspection of first surface or both surfaces in a compact system which can be easily integrated for in-line use.

Dark Field Solutions

• Specially designed Solid-State Laser Reflection (SSLR) scanners deliver the highest resolution in the industry (1μm); darkfield and brightfield scanner designs.
• Unique technology for first surface inspection or transmission inspection. Scratch/Dig and Edge defects. Inspect time 1- 4 seconds per wafer.
• Shape agnostic optics means that any shape can be inspected, on-line.
• Self-aligning optics means no more false hits or missed defects. No tuning.
• Most compact system in the world; easily integrated with robots, automation and tools.

First Surface Particle Detection – SSLR Images

First Surface Particle Detection – SSLR Images

First Surface Scratches – SSLR Images

Edge Chips – SSLR Images

Quality and Production Challenges

• Coated and Patterned Wafers must be defect-free or mapped to identify the unusable zones. Defects to 1μm must be detected, mapped and clusters identified.
• Manual inspection of Coated Wafers is time consuming, expensive, subjective and inexact; critical defects cannot be reliably detected. Finding defects in patterned wafers is even more challenging. Each wafer handling step adds defects, reducing yield.
• Conventional camera technologies do not deliver consistent high-speed, in-line inspection of first surface or both surfaces. These technologies cannot optically ignore the patterns.

Dark Field Solutions

• Coated and Patterned Wafers are mapped to identify the unusable zones. Defects to 1μm are detected, Clusters identified.
• Special optics eliminate the pattern, so only particles and other defects are mapped.
• High-speed, high-resolution, self-aligning system in a small installation envelope which can be integrated with robots/automation in-line.

Coating Pinholes

Grid and Active Area Defects, Patterned Wafer

Particle Detection, Patterned Wafer

Quality and Production Challenges

• 30% – 70% of coating defects are due to poor cleaning.
• It is imperative to measure first surface wafer cleanliness in order to ensure that only clean wafers are coated.
• Manufacturers of wafer cleaners do not provide a means to perform on-line 100% first surface cleanliness measurement. No way to ensure removal of polishing residue.
• Coating and patterning operations are flying blind. Post coating defects could have originated in the coater or the cleaner.

Dark Field Solutions

• Dark Field systems produce a Clean Number for each wafer.
• The Clean Number can be correlated with Post Coating defects; UCL can be created for Post Cleaning.
• When the Wafer Clean Number drops below the control limit, the wafer can be returned to the cleaner, avoiding being rejected after coating.

Quality and Production Challenges

• Via creation is critical for numerous high value wafer applications.
• Via damage – microcracks and microchips are typically not visible by eye.
• Microscope inspection is impractical; too slow and subjective. Handling increases defect counts.
• Automated via inspection systems are large and designed for off line, batch duty, slow.

Dark Field Solutions

• Dark Field systems provide 100%, high-speed inspection and via defect detection in a compact scanner which can be integrated with production.
• Via damage is automatically detected and mapped.
• G/NG wafer level decisions are generated. System is easily integrated with robots and hard automation.

Microscope and SSLR Images of Wafer Halo

Dark Field SSLR Halo Map

Post Coating of Headset Optics – Quality, Yield and Throughput Challenges

• Manual inspection is time consuming, expensive, subjective and inexact; critical defects cannot be reliably detected manually.
• Manual handling adds to the defects and yield loss.
• Production line speeds, limited line access and the need to find very small defects make manual inspection impossible.
• Conventional camera technologies do not deliver consistent high-speed inspection of first surface or both surfaces.

Dark Field Solutions

• Specially designed Solid-State Laser Reflection (SSLR) scanners deliver the highest resolution in the industry (1μm); darkfield and brightfield scanner designs.
• Special technology for first surface inspection or transmission inspection. Edge defect and chamfer defect detection. Inspect time 1-2 seconds per wafer.
• Self-aligning optics means no more false hits or missed defects due to misalignment.

Quality and Production Challenges

• Conventional haze measurement is an off-line statistically insignificant operation.
• Small samples are tested in a lab and results are generated sometimes hours after the fact – too late for effective, timely process control changes.
• The entire batch or production run is graded based on these samples.

Dark Field Solutions

• SSLR technology delivers 100% on-line, real-time haze measurement, and compares the haze values to upper and lower control limits.
• A Haze Map is produced. Those areas which violate the Haze Control Limits may be shown in different colors to make it easy for operators to interpret.
• The data is logged into SQL, XML, CSV files.

Haze Measurement – Glass Wafer

Quality and Production Challenges

• Coating uniformity measurement is a highly subjective, yet critical coating parameter.
• Coating thickness uniformity can be measured, but large area online thickness measurements are not possible.

Dark Field Solutions

• Dark Field SSLR scanners produce highly accurate coating uniformity measurements, area average, standard deviation and control limits.
• SSLR technology provides 100% on-line, real-time coating uniformity measurements and mapping.
• A Coating Uniformity Map is produced. Those areas which violate the Uniformity Control Limits may be shown in different colors to make it easy for operators to interpret. The data is logged into SQL, XML, CSV files.

Coating Uniformity Measurement – Glass Wafer