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Vertical DRAM Cell Structure Using Vertical Transistor in The Trench Capacitor

IP.com Disclosure Number: IPCOM000101351D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 4 page(s) / 101K

Publishing Venue

IBM

Related People

Wen, DS: AUTHOR

Abstract

Disclosed is a new self-aligned one-transistor vertical DRAM cell structure for very high density memory application. The feature of this structure is that the vertical transistor is located in the storage trench and is self-aligned to the trench. The technique of selective epi sidewall lateral growth is used. The vertical transistor, which can be either n-channel or p-channel, is formed on the epi layer. The cross-sectional view of the structure is shown in Fig. 1. Its corresponding top view is shown in Fig. 2. The detail process flow is described below and shown in Fig. 3. 1. Form the shallow trench isolation (STI); 2. Grow a thin layer of oxide, and deposit nitride for deep trench mask; 3. Etch trench through photoresist opening; 4. Fill up the trench with heavily doped poly, and planarize; 5.

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Vertical DRAM Cell Structure Using Vertical Transistor in The Trench Capacitor

       Disclosed is a new self-aligned one-transistor vertical
DRAM cell structure for very high density memory application. The
feature of this structure is that the vertical transistor is located
in the storage trench and is self-aligned to the trench.  The
technique of selective epi sidewall lateral growth is used.  The
vertical transistor, which can be either n-channel or p-channel, is
formed on the epi layer.  The cross-sectional view of the structure
is shown in Fig. 1.  Its corresponding top view is shown in Fig. 2.
The detail process flow is described below and shown in Fig. 3.
1.  Form the shallow trench isolation (STI);
2.  Grow a thin layer of oxide, and deposit nitride for deep trench
mask;
3.  Etch trench through photoresist opening;
4.  Fill up the trench with heavily doped poly, and
    planarize;
5.  Recess etch the poly in the trench;
6.  Remove the oxide on the trench sidewall;
7.  Selectively grow the epi through the trench sidewall;
8.  Gate oxidation to grow the gate oxide on the epi;
9.  Deposit poly gate and etch;
10. The basic DRAM structure is formed at this point.

      STRUCTURE VARIATION:
(1) Source/Drain Extension A layer of thin poly can be added on the
top of the nitride layer.  The final structure is shown in Fig. 4.
This poly layer can act as a source/drain extension to provide more
contact area for source/drain contact.
(2) Deep trench...