Image Sensors 

Cameras have revolutionized the way we see the world through our mobile devices. Pixel size has decreased and the array density increased to improve camera resolution. Additionally, laser-based sensors are now being combined to integrate distance and shape recognition.

CMOS Array Inspection

Quality control of CMOS arrays

As imaging technology has improved, the challenges related to manufacturing those devices has increased. Smaller, physical pixel size, larger array areas, better quantum efficiency all present challenges for quality control of this critical area. The ability to find sub-micron defects as well as macro-level variations within the array is important to ensure consistent response throughout the array area.

Rudolph enables inspection control for the array area with unique image processing, creative illumination and high resolution to ensure device yield.

VCSELs

Laser-based distance and imaging 

Vertical-cavity surface-emitting lasers or VCSELs provide laser-based distance and imaging which are now combined with CMOS imagers/cameras to allow the user to see the image and identify what and where it is. To achieve this level of sophisticated 3D imaging, strict defect control, accurate metrology, and advanced data analytics are required. The combination of devices and technologies require capability to find micro-defects in the most critical regions of the device or the technology will not work correctly.

By leveraging region-specific settings on a single device and a variety of optical tools, Rudolph creates an adaptive inspection solution to keep up with changing technologies.

Additionally, VCSEL formation requires the deposition and etching of multiple transparent and opaque films for beam formation, wavelength, and shape. Rudolph provides unique ellipsometry and acoustic metrologies required to control the deposition and etch processes.

Residue

Achieve proper color response

During the colorization phase of a CMOS image sensor, the ability to find even trace amounts of residue is critical for proper color response of the imager. Rudolph's unique approach to detecting residual films that are not visible through traditional microscopy allows image sensor manufacturers to be confident that their process is under control. Residue detection capability is an option that can be added to a high speed defect inspection system to ensure complete utilization of the asset.

Outside Logic

Logic surrounding the array

Image sensors have the added challenge of logic surrounding the array with very different requirements for inspection and metrology. Applying pattern-based algorithms in combination with probe mark inspection and 3D measurement technologies ensures that the entire device from array to functional electronics are designed correctly and within specified tolerances. Backside imagers utilizing TSV technology may benefit from highly accurate via depth and width measurements before or after wafer thinning and independent of the aspect ratio.

Cover Glass

Protection of the sensor

Final packaging for image sensors requires cover glass to protect the sensor and ensure long life of the device. Particles, glue residue, scratches and structural flaws in the glass all impact quality of the image even if the sensor itself is perfect. Glass substrate inspection poses certain challenges for handling and focusing. Final inspection of the image device also ensures that the attach process did not introduce foreign material residual glue that will render the device as no good.

Consulting and Applications Services

Rudolph's process control consulting services allow busy manufacturers to focus on production while we examine how to improve the process.

The Rudolph applications teams have over twenty years of experience with hundreds of successful projects worldwide across multiple industries. Contact us today to discuss your application study needs.

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