Sige Semiconductor, Inc.

Sige Microsystems Inc.

Derek C Houghton

Stephen Joseph Kovacic

Stephen J Kovacic

Hugues Lafontaine

A bipolar transistor is disclosed that is produced using a sacrificial mesa disposed over a layer of Si and SiGe in order to prevent a polysilicon covering layer from forming over a predetermined region of the Si and SiGe layer forming the transistor base. After an etching process, the sacrificial mesa is removed and the Si and SiGe layer is exposed, where an oppositely doped material is applied over top of the Si and SiGe layer to form an emitter. This makes it possible to realize a thin layer of Si and silicon germanium to serve as the transistor base. The transistor device formed using the sacrificial mesa results in the base layer Si and SiGe not being affected by a process of etching, as it otherwise would be using a conventional double-poly process, which results in a more repeatable bipolar transistor device yield.

Si-Ge base heterojunction bipolar device

A method of producing a bipolar transistor includes the step of providing a sacrificial mesa over a layer of SiGe in order to prevent a polysilicon covering layer from forming over a predetermined region of the SiGe layer forming the transistor base. After an etching process removes the sacrificial mesa and the SiGe layer is exposed, an oppositely doped material is applied over top of the SiGe layer to form an emitter. This makes it possible to realize a thin layer of silicon germanium to serve as the transistor base. This method prevents the base layer SiGe from being affected, as it otherwise would be using a conventional double-poly process.

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Gloucester, Canada

Derek C Houghton