Vlsi Technology, Inc.

William J Boardman

Kuang-Yeh Chang

Subhash R Nariani

Calvin T Gabriel

Vivek Jain

David P Chan

Edward D Nowak

Chung S Wang

Ying T Loh

The present invention relates to a flash EEPROM cell using polysilicon-to-polysilicon hot electron emission to erase the memory contents of the cell. Exemplary embodiments include a side gate, a control gate, a floating gate and source and drain regions. Appropriate biasing of these gates and source and drain regions controls the electron population of the floating gate. The memory cells may be of either the double polysilicon or triple polysilicon variety. Peripheral transistors are formed from a last formed polysilicon layer to avoid degrading the peripheral transistors.

Method of making flash memory cell

A method for making an anti-fuse structure characterized by the steps of forming a conductive base layer; forming an anti-fuse layer over the base layer; patterning the anti-fuse layer to form an anti-fuse island; forming an insulating layer over the anti-fuse island; forming a via hole through the insulating layer to the anti-fuse island; forming a conductive connection layer over the insulating layer and within the via hole; and patterning the conductive connection layer to form a conductive contact to the anti-fuse island. Preferably, the anti-fuse island comprises amorphous silicon which can optionally be covered with a thin layer of a titanium-tungsten alloy.

Method for making cusp-free anti-fuse structures

An anti-fuse structure characterized by a substrate, an oxide layer formed over the substrate having an opening formed therein, an amorphous silicon material disposed within the opening and contacting the substrate, a conductive protective material, such as titanium tungsten, disposed over the amorphous silicon material, and oxide spacers lining the walls of a recess formed within the protective material. The protective material and the spacers provide tighter programming voltage distributions for the anti-fuse structure and help prevent anti-fuse failure.

Method for making anti-fuse structures

For a structure with an overlapping gate region, a first insulator layer is placed on a substrate. A source/drain polysilicon layer is placed on the insulator layer. The source/drain polysilicon layer is doped with atoms of a first conductivity type. A second insulator layer is placed on the source/drain polysilicon layer. A gap is etched in the second insulator layer and the source/drain polysilicon layer to expose a portion of the first insulator layer. The exposed portion of the first insulator layer and an additional amount of the first insulator layer under the second insulator is etched so as to enlarge the gap and to undercut a portion of the source/drain polysilicon layer. Two polysilicon filler regions are formed which fill a portion of the gap including the undercut area under the source/drain polysilicon layer. A gate polysilicon region is formed in the gap and extends over the source/drain polysilicon layer. The gate polysilicon region is separated from the source/drain polysilicon layer and the polysilicon filler regions by a dielectric region. Source/drain regions are formed by atoms in the source/drain polysilicon layer diffusing through the polysilicon filler regions into the substrate.

Method of making extended polysilicon self-aligned gate overlapped

An anti-fuse structure characterized by a substrate, an oxide layer formed over the substrate having an opening formed therein, an amorphous silicon material disposed within the opening and contacting the substrate, and oxide spacers lining the walls of a recess formed within the amorphous silicon. The spacers prevent failures of the anti-fuse structures by covering cusps formed in the amorphous silicon material. The method of the present invention forms the above-described anti-fuse structure and further solves the problem of removing unwanted spacer material from areas outside of the anti-fuse structure locations.

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San Jose, CA, United States of America

William J Boardman