Tower Semiconductor Develops Stitching Technology for Ultra-High Resolution CMOS Image Sensors.

MIGDAL HAEMEK, Israel--(BUSINESS WIRE)--Jan. 20, 1999--

Innovative Process Merges Multiple Design Structures

to Incorporate High Pixel Count Onto Sensors

Without Encountering Photolithography Limitations

Tower Semiconductor Ltd. (NASDAQ:TSEMF) today announced that it has developed a stitching process that enables the manufacturing of ultra high resolution CMOS image sensors (CIS).

The new process allows the physical merger of multiple design structures onto a wafer during the photolithography process, creating a single CIS containing millions of pixels and avoiding the size limitation imposed by the exposure field of lithography steppers.

Digital still cameras require an ultra-high resolution image sensor to produce pictures with quality similar to, or even higher than, that achieved by conventional 35 millimeter film-based cameras. To achieve high resolution, image sensors integrate as many pixels as possible into a single chip. However, the more pixels required, the larger the size of the die. When using modern stepper photolithography equipment, which has a fixed, relatively small exposure field, the large die may easily exceed the limited exposure field.

Using smaller pixels is not practical, as it requires sharper focusing of the light to overcome the interference phenomenon and therefore necessitates much higher quality lenses. Such lenses may cost an order of magnitude more than standard photography lenses used today, leading to higher system cost. A better and more cost-effective solution is to overcome the limitation of exposing a die larger than the exposure field.

Tower's stitching technology overcomes the limits of the stepper exposure field and allows Tower's customers to manufacture high-quality image sensors with ultra high resolutions. The stitching technology allows the physical merger of several design structures on the wafer to create a single CIS. The stepper exposes one such design structure at a time.

A high-precision alignment method allows these structures to slightly overlap, fusing them into a single integral chip. The wafer is manufactured, and the chip tested, sawed and packaged as an integral unit. The stitched chip is for all practical purposes the same as a chip manufactured in the standard manner.

"We have developed the stitching technology in response to requests from our customers who wish to use Tower's high-quality CMOS processes to manufacture ultra high resolution image sensors," said Reuven Marko, vice president of marketing and sales at Tower. "This unique technology enables our customers to push the boundaries of systems based on CMOS image sensors, and to effectively compete with the older charged coupled device (CCD) technology.

"Large CIS arrays also will yield substantially better than CCD sensors, as unlike in CCD, the CIS pixels are not coupled electrically for the sensor operation. We see the stitching technology as an important element in our strategy to focus on CIS foundry services, in addition to our embedded non-volatile memory processes."

Guy Meynants, senior design engineer, CMOS imagers, for IMEC, Europe's leading center for microelectronics research, said, "We have already used Tower's stitching technology for a device designed in a 0.5-micron process that would otherwise not be producible. Even when inspected using a microscope, it is virtually impossible to detect the stitching borders on the Tower-produced device."

The new stitching technology complements Tower's image sensor portfolio, which includes optical characterization of the CMOS process, optical vehicle to monitor the fabrication, in-house color filter deposition, and optical sort and optical packaging. In addition Tower has established alliances with several leading design centers specializing in CMOS image sensor technologies. This allows Tower be a one-stop shop for the design and manufacture of Application Specific Image Sensors (ASIS(TM)).

Tower Semiconductor Ltd. is an independent manufacturer and service provider of semiconductor integrated circuits (ICs) on silicon wafers. As a foundry, Tower provides IC design, manufacturing and turnkey services, using advanced production capabilities and the proprietary IC designs of its customers, and is specializing in providing solutions for embedded non-volatile memory devices and CMOS image sensors. ICs manufactured by Tower are incorporated into a wide range of products in diverse and rapidly growing markets, including computer and office equipment, communication products and consumer electronics.

This press release includes forward-looking statements, which are subject to risks and uncertainties. Actual results may vary from those projected or implied by such forward-looking statements. Potential risks and uncertainties include, without limitation, risks and uncertainties associated with the (i) development and introduction to production of the Company's CMOS Image Sensor technologies, including its new stitching technology, (ii) development and introduction to production of the Company's other advanced CMOS technologies which are currently under development, (iii) market acceptance and competitiveness of the products to be manufactured by Tower for customers using said technologies, and (iv) conditions in the market for semiconductor products generally. A more complete discussion of risks and uncertainties which may affect the accuracy of these statements and Tower's business generally, is included at "Item 1. Business -- Factors Which May Influence Future Results and Accuracy of Forward-Looking Statements" in Tower's most recent Annual Report on Form 20-F as filed by Tower with the Securities and Exchange Commission.

ASIS(TM) is a trademark of Tower Semiconductor Ltd. (Other trademarks are the property of their respective holders.)