Abstract: A process for fabricating a gate oxide of a vertical transistor. In a first step, a trench is formed in a substrate, the trench extending from a top surface of the substrate and having a trench bottom and a trench side wall. The trench side wall comprises a <100> crystal plane and a <110> crystal plane. Next, a sacrificial layer having a uniform thickness is formed on the trench side wall. Following formation of the sacrificial layer, nitrogen ions are implanted through the sacrificial layer such that the nitrogen ions are implanted into the <110> crystal plane of the trench side wall, but not into the <100> crystal plane of the trench side wall. The sacrificial layer is then removed and the trench side wall is oxidized to form the gate oxide.

Abstract: 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.

Abstract: A method for controlling isolation layer thickness in deep trenches for semiconductor memories in accordance with the present invention includes the steps of providing a deep trench having a storage node formed therein, the storage node having a buried strap, depositing an isolation layer on the buried strap for providing electrical isolation for the storage node, forming a masking layer on the isolation layer to mask a portion of the isolation layer in contact with the buried strap and removing the isolation layer except the portion masked by the mask layer such that control of a thickness of the isolation layer is improved. A method for fabricating vertical transistors by recessing a substrate to permit increased overlap between a transistor channel and buried strap outdiffusion when the transistor is formed is also included. A semiconductor device is also disclosed.

Abstract: A pad layer disposed on a semiconductor substrate 102 and a buffer layer 108 disposed within the pad layer such that the pad layer is divided into a dielectric layer 106 below the buffer layer and a mask layer 110 above the buffer layer. A method of forming layers with uniform planarity and thickness on a semiconductor chip includes the steps of providing a substrate having a thermal pad 106 formed thereon, forming a dielectric layer 106 on the thermal pad, forming a buffer layer 108 on the dielectric layer wherein the buffer layer is made from a different material than the dielectric layer and forming a mask layer 110 on the buffer layer wherein the buffer layer is made from a different material than the mask layer.