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Dendritic Polysilicon for DRAM Capacitors

IP.com Disclosure Number: IPCOM000106542D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Acovic, A: AUTHOR [+4]

Abstract

Disclosed is a process for growing polysilicon dendritically on oxide, so that the total surface area of the polysilicon can be much greater than the surface area of the oxide on which the polysilicon is grown and hence the capacitance of a capacitor structure grown on the polysilicon can be much increased.

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This is the abbreviated version, containing approximately 53% of the total text.

Dendritic Polysilicon for DRAM Capacitors

      Disclosed is a process for growing polysilicon dendritically on
oxide, so that the total surface area of the polysilicon can be much
greater than the surface area of the oxide on which the polysilicon
is grown and hence the capacitance of a capacitor structure grown on
the polysilicon can be much increased.

      As cell sizes decrease in coming generations of DRAM chips,
there is insufficient area on each cell to use the present DRAM
capacitor designs.  The surface area of the capacitor must be
increased in some novel way.

Three process embodiments are suggested:

1.  The nucleation of the polysilicon film can be controlled by
    controlling the partial pressure of the feed gas (silane or
    disilane), and the temperature.  We propose that the surface
    morphology of the polysilicon can be controlled by first
    nucleating a certain number density of polysilicon nuclei, then
    rapidly raising the temperature so that the nucleation rate no
    longer controls the silicon growth rate, but rather the growth
    rate is controlled by the diffusion of the feed gas to the
    surface.  If the partial pressure of, for example, silane , is in
    the millitorr region, and the total pressure is above an
    atmosphere with the addition of an inert gas such as helium, a
    starting temperature of 500ºC for one minute will give a
    density of about 1E10 nuclei/cm sup(2)  Raisin...