Semiconductor devices are becoming smaller and more dense with the evolution of new technology. However, increases in circuit density produce a corresponding increase in overall chip failure rates at a time when chip failure rates must decrease to remain competitive. Chip manufacturers are therefore challenged to improve the quality of their products by identifying and eliminating defects which produce defective chips known as fails. Whereas significant improvements are being made to eliminate systematic defects by reducing process variability. Process improvements alone are not sufficient to eliminate all the random defects which effect both yield and reliability. Historically, screening techniques have been employed to improve product failure rates to acceptable levels by culling out many of these random defects.
Single chip or multi-chip packaging strategies require the ability to join or replace individual chips from an assembled chip module. This should of course be done without altering the integrity of the remaining chips or capacitors or other electronic components. Chip changing is also required for yield management, upgrade capability, and engineering changes, to name a few. Chip replacement typically involves three distinct steps: chip removal, chip site solder dress, and new chip rejoin. Different tools and processes are used in the chip removal or chip join process.
U.S. Pat. No. 3,283,124 (Kawecki), discloses a selective heating apparatus where energy from an infrared source is focused through the use of a special focusing means.
U.S. Pat. No. 4,160,893 (Meyen et al.) discloses an individual chip joining machine, where an IR lamp is used to heat the upper surface of a chip through a flat quartz plate.
U.S. Pat. No. 4,278,867 (Tan) discloses a system for chip joining by short wavelength radiation. Tan uses a laser to heat the upper or back-side surface of a chip during the process.
IBM Technical Disclosure Bulletin, "Luminous Dual Reflection Lamp" Vol. 20, No. 6, Pages 2141-2142 (November 1977), discloses a lighting system for uniformly scattering light without projecting either characteristic central hot spots or concentrated filament images. This is achieved by using a flat clear quartz plate, having a reflecting convex portion and a concave reflector.
Puttlitz, et al., "Replacing Flip Chips on MLC Multichip Modules Using Focused Infrared (IR): The Basics", ISHM '92 Proceedings, Pages 384-390 (October 1992), discloses a means of locally heating a target chip, site dressing the chip site, and placing and reflowing a replacement chip. This is done by using an infrared (IR) quartz-halogen lamp within a metal reflector housing. The IR lamp is typically located at or near the parabolic reflector focal point so that its energy can be directed and focused onto the backside of the target chip. Heating can, however, be confined to the target chip by introducing a substrate shield that prevents irradiating the surrounding MCM surface and attachments. This assures that only the target chip is irradiated (i.e., heated) when the IR lamp is energized.