The Reserch Of Flip-chip Bonding Technology About Hybridfocal Plane Array Detector

The cut-off wavelength of the UV detector which is made from the third generation semiconductor material GaN, is 365 nm.AlxGa(1-x)N is obtained by doping GaN with Al. The wavelength of Alx Ga( 1-x)N can be adjusted between 200 nm and 365 nm continuously by controlling the content of Al. When the parameter x of Alx Ga(1-x)N equals 0.38, the material is called the high aluminum component material. The cut-off wavelength of this material drops to 290 nm, and the material is absolutely solar-blind. The solar-blind detector has no response to visible light or infrared light, which is of important significance for detecting ultraviolet in the infrared light and visible light environment. Besides the insensitivity to ultraviolet, the UV-FPA(Ultra Violetray-Focal Plane Array)also has the advantages of high quantum efficiency, large dynamicrange and low noise amplification. It is not only used for military purposes, but also widely used in civil applications, such as corona detection in high voltage transmission.Flip chip is one of the key technologies for UV-FPA development. The main processes of flip chip, namely the preparation of indium bump, Hybridized interconnection and underfill process is researched in this thesis. In order to reflow indium bump, it changes the UBM to invasive inner and no invasive outer structure. By using the glycerin to reflow the indium bump at 180 ℃, a 320×256 uniform indium bump array is obtained, whose pitch is 30 um, height is more than 10 um, and growth rate is larger than 99.9%.In this thesis, the testing method of FPA about flip chip process is introduced, and the influence of the bonding temperature, the bump height and the warpage of the chip to flip chip is analyzed. The flip chip bonding process to assemble the sapphire(detector based on GaN) and silicon(ROIC)material isoptimized. The indium is selected for its faster stress release, stronger shear resistance and lower bonding temperature behavior in bonding process, the oxidation is prevented by clean the bump surface again before bonding and change the bond mode to cold pressure bond. the laser leveling function on FC150(bonding device) is using to the flatness of the detector surface no more than 2μm. More than 99% bumps of a UV-FPA under the conditions(80℃、8Kg、180s)is bonded successfully when the bump height reach to 10μm.thermal mismatch is the reason of the reliability problem while the sapphire and the silicon is bonded together. Following to the principle of fluid motion, the underfill process for UV-FPA device with the gap width less than 10μm is developed, the UV-FPA which is more than 7.6mm width can be filled successfully by using the glue which viscosity is 0.5Pa·s, placed time no more than 1h, and the speed of filling is 0.2mg/min. Developed the flip-chip bonding process lays a solid foundation for the development of the high reliability and low blind-pixel UV-FPA detector.