Fabrication of a low defect germanium film by direct wafer bonding

A method of fabricating a low defect germanium thin film, comprising:

• preparing a silicon wafer for germanium deposition;
• forming a germanium film using a two-step CVD process, wherein a first CVD step is performed at a temperature of between about 250° C. to 300° C., to form a continuous germanium film, and wherein a second CVD step is performed at a temperature of about 700° C., to form a relaxed germanium thin film;
• depositing a layer of germanium on the relaxed germanium thin film.
• annealing the germanium thin film using a multiple cycle process, wherein a first cycle is performed at a relatively higher temperature of between about 840° C. to 900° C., and a second cycle is performed at a relatively lower temperature of between about 750° C. to 840° C., and wherein the first and second cycles are altered for between about 10 to 40 cycles to concentrate any defects in the germanium thin film in a region near the germanium/silicon interface, wherein each cycle of the multiple cycle process has a duration of between about one minute to five minutes;
• implanting hydrogen ions;
• depositing a layer of tetraethylorthosilicate oxide (TEOS);
• smoothing the TEOS layer by CMP;
• cleaning the TEOS layer;
• preparing a counter wafer;
• bonding the germanium thin film to the counter wafer to form a bonded structure;
• annealing the bonded structure at a temperature of at least 375° C. to facilitate splitting of the bonded wafer;
• splitting the bonded structure to expose the germanium thin film;
• removing any remaining silicon from the germanium thin film surface along with a portion of the germanium thin film defect zone;
• and
• incorporating the low-defect germanium thin film into the desired end-product device.