| Summary: | 碩士 === 國立交通大學 === 材料科學與工程系 === 91 === In this study, direct wafer bonding technology was used to bond GaAs wafers .Before bonding, the organic solutions were only used to preserve native oxide layer. The annealing temperature, bonding type is our variables, the mechanical strength, electrical characteristic and interface morphologies were investigated by different conditions.
The mechanical strength of bonded interfaces was measured by pull test.The minimum strength is presented at 600 degree. This is due to the morphologies of oxide layer become from continuous type to hemisphere type (discontinuous).From EDS and diffraction pattern of hemisphere region , it is composed of defects and amorphous substances. So the strength is very weak compared with other regions. The cracks often occurred here during pull test.
The I-V curves were depend on the dopant in GaAs wafers , the resistances of N-type GaAs bonded wafer at 850 degree is large than that was at lower temperature , this is due to the acceptor level which was induced by the
diffusion of oxygen at high temperature .This would result in lower majority carrier (electron) ,and the slop of I-V curves could become small .On the other hand, the electrical properties of P-type GaAs bonded wafers are improved by the increase of annealing temperature .
The different bonded type (anti- or in phase) have some effects on electrical properties.In general, the in-phase bonded type has better electrical properties than anti-phase. The defects and oxide layer are more easily trapped by anti- phase bonded interface which is a barrier for carrier transportation.
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