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Noise Suppression Techniques for Buried Plate Trench Memory Array

IP.com Disclosure Number: IPCOM000107689D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 5 page(s) / 144K

Publishing Venue

IBM

Related People

Hwang, W: AUTHOR [+2]

Abstract

Disclosed is a method of partitioning the well structure to solve the well-bouncing and plate noise problems in a buried-plate trench DRAM. The proposed structure and fabrication method to form highly conductive, dummy shallow and deep trench rings in the isolated p-well and n-plate configuration are described as follows.

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Noise Suppression Techniques for Buried Plate Trench Memory Array

       Disclosed is a method of partitioning the well structure
to solve the well-bouncing and plate noise problems in a buried-plate
trench DRAM.  The proposed structure and fabrication method to form
highly conductive, dummy shallow and deep trench rings in the
isolated p-well and n-plate configuration are described as follows.

      (1) Begin with a wafer with p- epi on p+ substrate, forming a
deep buried-plate trench (BPT) by known technology.  The trench
consists of two portions.  The shallow upper portion is formed by a
thick sidewall dielectric (oxide) collar layer while the deep lower
portion is formed without a dielectric layer.  Next, form the buried
isolated n-well by out-diffusion N+ dopant from the trench by known
methods (Fig. 1).

      (2) Grow thin oxide/nitride composite layers in the trench to
produce the storage capacitor insulator.  Pattern and remove the thin
oxide/nitride composite layers from the selected dummy deep trenches
(or trench rings) (Fig. 2).

      (3) Fill the trench with chemical-vapor deposition (CVD) n+
poly- Si.  The  filled dummy trenches (or trench rings) form the
conducting plate-noises shielded rings (Fig. 3).

      (4) Recess n+ poly-Si in the selected dummy trenches. Refill
with oxide (TEOS).  Etch back the oxide and the collar in the dummy
shallow trenches (Fig. 4).

      (5) Fill and planarize the dummy shallow trench with chemical-
vapor deposition (CVD) p+ poly-Si.  The filled dummy shallow trench
(or trench rings) form...