Deep trench DRAM with SOI and STI
AssigneeWinbond Electronics Corp.
InventorWei-Lin Shen
Life of this patent
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Abstract
A method of forming dynamic random access memory (DRAM) comprising a deep trench capacitor with two electrodes and a node dielectric. The deep trench capacitor is formed by etching a deep trench, making a node dielectric on the surface of the trench, and filling the trench with poly-Si. The method also employs silicon on insulator (SOI) technology to form a single crystal Si layer on an insulator above the trench. The SOI is then contacted with the poly-Si electrode of the trench capacitor, and a transistor is fabricated above the trench capacitor. The method enables fabrication of a transistor above the trench capacitor and thereby frees space on the DRAM chip to allow for a greater density of devices on the DRAM chip.
Claims7
A semiconductor device for DRAM, comprising:
- a silicon substrate defining a horizontal plane;
- a deep trench capacitor comprising a deep trench etched into said silicon substrate perpendicular to the horizontal plane, a dielectric formed on a sidewall of the deep trench, and a poly-Si plug filling the deep trench;
- an insulator layer formed above said deep trench capacitor, wherein said insulator layer includes an open window located above said poly-Si plug;
- a silicon device layer formed above said insulator layer, wherein a portion of said silicon device layer forms a contact region residing in the open window of the insulator layer;
- a shallow trench isolation structure formed through the silicon device layer;
- wherein said shallow trench isolation structure comprises a shallow trench etched into said silicon device layer such that at least one wall of the shallow trench is inclined with respect to an axis perpendicular to said horizontal plane;
- and
- a source/drain region for a transistor formed in an upper surface of the silicon device layer, wherein at least a portion of the source/drain region is located above the deep trench capacitor and is in contact with the contact region via conductive walls of the shallow trench isolation structure.
Dependencies are inferred from the claim text.