Browse Prior Art Database

Re-Entrant Storage Trench Profile

IP.com Disclosure Number: IPCOM000041110D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Drake, CE: AUTHOR [+2]

Abstract

A method is reported for increasing the storage capacitance of a semiconductor trench storage node without increasing the layout area.

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Re-Entrant Storage Trench Profile

A method is reported for increasing the storage capacitance of a semiconductor trench storage node without increasing the layout area.

A plan view and cross-section of a trench storage node with a re-entrant profile for the purpose of increasing the capacitive storage area is shown in Fig.
1. The energy Q stored in a memory cell's trench storage node is directly proportional to node capacitance Cs and to the second power of the potential difference WV between the plates of the storage capacitor, therefore, Q = CsWV. By increasing the storage capacitance, an improved signal to noise is realized.

Through the utilization of sidewall space technology as an etch mask and the introduction of silicon implant damage to enhance higher oxidation rates, a re- entrant storage trench profile is fabricated as outlined in Figs. 2 - 6.

A standard trench etch pad shown in Fig. 2 is fabricated by growing an oxide 10 on a silicon substrate 11 followed by the deposition of a film of silicon nitride 12 and a layer of oxide 13 on top. A directional etch back to the silicon substrate 11 is performed to complete the pad. Fig. 3 shows a film of silicon nitride 14 deposited on top of oxide 13 followed by a chemical vapor deposition (CVD) of oxide 15. Fig. 4 shows the formation of side wall spacers 15 to be utilized as an ion implant mask. Silicon is implanted to introduce silicon lattice damage 16 to substrate 11 in support of a higher oxidation rate than...