| 摘要 |
A heterojunction bipolar transistor (HBT) device structure is provided which facilitates the reduction of the base-collector capacitance and a method for making the same. The base-collector capacitance is decreased by fabricating a base micro-bridge connecting a base contact to a base mesa on the HBT. The base micro-bridge is oriented along about one of 001, 010, 00{overscore (1, and 0{overscore (10 direction to a major flat of the wafer. The HBT device employs a phosphorous based collector material. During removal of the phosphorous based collector material, the base layer is undercut forming the micro-bridge, successfully removing the collector and sub-collector material below the bridge due to the orientation of the micro-bridge. The removal of collector and sub-collector material reduces the base-collector junction area, and therefore reduce the base-collector junction capacitance.
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