Taiwan Semiconductor Manufacturing Comp. Ltd.

Huan-Wen Wang

Sen-Fu Chen

Chih-Heng Shen

Ching-Wen Cho

Ying-Tzu Yen

Feng-Yuan An

Yuan-Ko Hwang

A method for fabricating a polysilicon emitter bipolar transistor employs a pair of ion implant methods. A first of the ion implant methods implants a portion of an intrinsic base region interposed between an extrinsic base region and a polysilicon emitter layer with an amorphizing non-active dopant. A second of the ion implant methods implants the polysilicon emitter layer with an active dopant to form a doped polysilicon emitter layer. The polysilicon emitter bipolar transistor is fabricated with enhanced performance.

Amorphizing ion implant method for forming polysilicon emitter bipolar transistor

A method for fabricating a polysilicon emitter bipolar transistor employs a pair of ion implant methods. A first of the icon implant methods implants a portion of an intrinsic base region interposed between an extrinsic base region and a polysilicon emitter layer with an amorphizing non-active dopant. A second of the ion implant methods implants the polysilicon emitter layer with an active dopant to form a doped polysilicon emitter layer. The polysilicon emitter bipolar transistor is fabricated with enhanced performance.

A device with a plurality of structures with different resistance values is formed on a substrate. A polysilicon layer is formed upon the substrate. A silicon oxide layer is formed over the substrate. A hard masking layer is formed over the silicon oxide layer. The hard masking layer includes a full thickness portion and a thinner portion. The polysilicon layer below the full thickness portion is lightly doped forming a high resistance region. Below the thinner portion the polysilicon layer is heavily doped forming a low resistance region. However, in spite of the differences in resistance, the high resistance region and the low resistance region have the same thickness.

Polysilicon structures with different resistance values for gate electrodes, resistors, and capacitor plates

A method is disclosed to form a reliable silicon nitride spacer between the lower edges of the floating gate and the control gate of a split-gate flash memory cell. This is accomplished by forming a floating gate with vertical sidewalls, forming a high temperature oxide layer followed by silicon nitride layer over the floating gate including the vertical sidewalls, ion implanting the nitride layer and then selectively etching it to form a robust silicon nitride spacer of well defined rectangular shape.

Implant method for forming Si3N4 spacer

A method to prevent threshold shifts in MOS transistors due to auto-doping from heavily doped polysilicon layers. Isolation regions are provided in a semiconductor substrate separating active areas. A gate oxide layer is formed over the surface of the semiconductor substrate. A polysilicon layer is deposited overlying the gate oxide layer. A tungsten silicide layer is deposited overlying the polysilicon layer. The tungsten silicide layer and the first polysilicon layer are etched to form MOS gates and bottom electrodes for dual polysilicon capacitors. An interpoly dielectric layer is deposited overlying entire surface of the semiconductor substrate. A doped polysilicon layer is deposited overlying the interpoly dielectric layer. A sealing oxide layer is deposited overlying the doped polysilicon layer to prevent out-diffusion of impurity ions into the semiconductor substrate and thereby preventing auto-doping. The tungsten silicide layer is annealed. Ions are implanted to form drain and source regions. The fabrication of the integrated circuit device is completed.

Method to prevent auto-doping induced threshold voltage shift

This method forms structures with different resistance values from a single polysilicon film formed on a substrate. Form a hard masking layer on the polysilicon film. Form a photoresist mask over the hard masking layer. Partially etch the hard masking layer through the photoresist mask to reduce the thickness of the polysilicon while leaving the remainder of the hard masking layer with the original thickness. The thickness is reduced in locations where a low resistance is to be located in the polysilicon film. Then dope the polysilicon layer through the hard masking layer with variable doping as a function of the reduced thickness and the original thickness of the hard masking layer.

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Hsin-Chu, Taiwan

Huan-Wen Wang