International Business Machines Corporation

Subodh K Kulkarni

Louis L Hsu

Seshadri Subbanna

Klaus D Beyer

Manu J Tejwani

Paul Andrew Ronsheim

Ronald W Knepper

Russell C Lange

Robert K Cook

Bob H Yun

A method of controlling the interfacial oxygen concentration of a monocrystalline/polycrystalline emitter includes the steps of: passivating the monocrystalline silicon surface by immersing the wafer in a diluted HF acid solution; transferring the wafer into a high vacuum environment; heating the wafer to between 400.degree. and 700.degree. C.; exposing the monocrystalline silicon surface to a gas having a partial pressure of oxygen of between 10.sup.-5 to 1 Torr for between 1 and 100 minutes; and, depositing polysilicon onto the monocrystalline silicon surface.

Method for controlling interfacial oxide at a

A process for forming air-filled isolation trenches in a semiconductor substrate by a conformal chemical vapor deposition (CVD) of a silicon dioxide layer over the passivated surface of the semiconductor substrate in which intersecting trenches have been formed and partially filled with a material that can subsequentially be removed from under the CVD silicon dioxide layer, such materials include water soluble glasses and polymeric materials, such as a polyimide. The CVD silicon dioxide is etched back to the passivated surface of the semiconductor substrate, forming openings in the layer at the trench intersections that extend to the trench fill material. The fill material is removed through these openings. A CVD silicon dioxide layer is deposited to fill the openings, leaving a silicon dioxide cap bridging the air-filled trench. Water soluble glasses that may be used to fill the trench include BSG glass (B.sub.2 O.sub.3 content greater than 55%) and germanosilicate glass (GeO.sub.2 content greater than 50%). A polymer fill, such as a polyimide, if used, may be removed by plasma etching in O.sub.2.

Air-filled isolation trench with chemically vapor deposited silicon

Growing community of inventors

Fishkill, NY, United States of America

Subodh K Kulkarni