TLC International (Phoenix, AZ) (www.tlcinternational.com) used the recent Microdisplay 2001 conference to demonstrate a second-generation substrate cutting machine. While still in development, the TLC Phoenix-600 has already shown the ability to accurately and cleanly separate individual LCOS display dies from a glass-silicon lamination assembly. Once perfected, the company believes the machine will offer a superior singulation solution at a lower overall cost.

Singulation is the process that separates each individual display die from a laminated substrate containing many displays. For LCOS displays, this lamination consists of a silicon wafer and a glass substrate joined together, but separated slightly by spacers. Singulation is needed to produce an individual display die so that it can be filled with liquid crystal and packaged.

But singulation methods have been difficult to develop for this lamination assembly because the two dissimilar materials present some unique challenges. Several approaches have been tried that use rotating diamond saws, typical of the semiconductor industry, and scribe-and-break methods, familiar in the LCD industry. Even hybrid approaches have been tried. Great care must be taken to not contaminate the display die, induce micro-fractures, or allow debris to cause cosmetic damages to the glass surface. Current approaches, says TLC, are slow and costly.

In the system developed by TLC, a tungsten carbine blade wheel is used to singulate the devices. The company developed the process so that it requires no oil or water lubrication, thus avoiding potential contamination issues. The rotating blade is used to only partially cut both sides of the lamination so that it can be easily broken later.

TLC claims it is the first to use a single CCD camera mounted in the cutting head instead of two CCDs mounted on an overhead gantry. Also unique is the fact that the cutting head moves and rotates so that the 24-inch square stage can remain stationary. All of this simplifies the design and lowers equipment cost. Also included is proprietary software that allows quick setup and target alignment plus a unique on-stage measurement/inspection feature that allows an operator to measure and tolerance inspect scribes for quality assurance purposes.

The second generation system allows operators to download AutoCAD.DXF files that will guide the cutting machine to cut arbitrary shapes as well as full sheet nesting or clustering layouts. This means more efficient use of the silicon real estate enabling more devices per wafer and lower per-display costs.

Currently, the company is putting the final touches on their target sensing systems for cutting of the silicon. Here, the challenge is to be sure that the cuts on the opaque silicon substrate are aligned properly with those on the glass side. The company believes a final calibration to support LCOS singulation will be ready for shipment by Q1'02.

But the machine can be used to cut shapes too, so it can be used for production of many other optical elements such as dichroic filters, cold and hot mirrors, sensors, color filters, etc. Circles and filet cornered rectangles are standard pre programmed shapes, but custom shapes can be accommodated too via the downloaded CAD files.

TLC International asserts that no other computer controlled, mechanical glass scriber capable of shapes and rectilinear cuts is available in the world at a more affordable cost. Several second generation machines have been installed in the past few months, and customers already report substantial material cost savings, higher yields per substrate, and increased profits.

Currently, the Phoenix-600 sells for $80K but some cost increases can be expected for equipment to support silicon wafer cutting for LCOS laminations.

Contact: TLC International, Maribeth Linden, 1 602 866 8208 or