Siemens Aktiengesellschaft

International Business Machines Corporation

Siemens Microelectronics Limited

Hans-Oliver Joachim

Jochen C Beintner

Ulrike Gruening

Jack Allan Mandelman

Rajesh Rengarajan

Rajesh Rengarajah

A semiconductor structure comprises first gate conductors which wrap around N-wells of buried-channel P-type metal oxide semiconductor field effect transistors and second gate conductors which do not wrap around P-wells of surface-channel N-type metal oxide semiconductor field effect transistors and a method of manufacturing the same comprises forming insulators adjacent each of the N-wells and the P-wells, protecting the N-wells with a patterned mask, forming first divots in areas of the insulators adjacent the N-wells and forming second divots in areas of the insulators P-wells, wherein the first divots have a greater depth than the second divots.

Deep divot mask for enhanced buried-channel PFET performance and reliability

A method is provided for fabricating a first and second MOSFET transistors in different electrically isolated active areas of a semiconductor body, each one of the transistors having a plurality of layers. A first gate oxide layer and a first poly-crystalline silicon layer are deposited over the semiconductor body over the active areas. Trenches are etched in said first gate oxide and poly-crystalline silicon layers and said semiconductor body to delineate the first and second active areas, thereby forming first delineated gate oxide layer and poly-crystalline silicon layers coextensive with the first active area. Material is deposited in said trenches to form the active area isolations, the active area isolations having a top surface above said semiconductor body. A masking layer is then formed over said first and second active areas and selective portions of it are removed to expose said second active area. The masking layer and the active area isolations together form a mask defining an opening coextensive with the second active area with the active area isolations defining said opening. Material through the opening to form a second gate oxide layer and a second poly-crystalline layer, such second layer and second poly-crystalline layer being coextensive with the second active area. The first transistor with the first delineated gate oxide and poly-crystalline layer as a pair of the plurality of layers of the first transistor and the second transistor with the second gate oxide layer and second poly-crystalline layer as a pair of the plurality of layers of the second transistor.

Method for fabricating transistors

A pair of memory cells for use in a DRAM are formed in a monocrystalline bulk portion of a silicon wafer by first forming a pair of vertical trenches spaced apart by a bulk portion of the wafer. After a dielectric layer is formed over the walls of each trench, the trenches are each filled with polycrystalline silicon. By a pair of recess forming and recess filling steps there is formed at the top of each trench a silicon region that was grown epitaxially with the intermediate bulk portion. Each epitaxial region is made to serve as the body of a separate transistor having its drain in the lower polysilicon fill of a trench, and its source in the monocrystalline bulk intermediate between the two epitaxial regions. The lower polysilicon fill of each trench is also made to serve as the storage node of the capacitor of each cell, with the bulk serving as the other plate of the capacitor.

Memory cell structure and fabrication

A semiconductor structure comprises first gate conductors which wrap around N-wells of buried-channel P-type metal oxide semiconductor field effect transistors and second gate conductors which do not wrap around P-wells of surface-channel N-type metal oxide semiconductor field effect transistors and a method of manufacturing the same comprises forming insulators adjacent each of the N-wells and the P-wells, protecting the N-wells with a patterned mask, forming first divots in areas of the insulators adjacent the N-wells and forming second divots in areas of the insulators adjacent P-wells, wherein the first divots have a greater depth than the second divots.

Growing community of inventors

Wappingers Falls, NY, United States of America

Hans-Oliver Joachim