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A NEW ISOLATION PROCESS FOR VARIABLE WIDTH AND DEPTH TRENCHES BY USING A GLASS FRIT/POWDER

IP.com Disclosure Number: IPCOM000006737D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2002-Jan-28
Document File: 2 page(s) / 112K

Publishing Venue

Motorola

Related People

Henry G. Hughes: AUTHOR [+4]

Abstract

The ability to form variable width and variable depth isolation regions on the same device has been diicult to achieve in high density semiconductor devices. A new method for planatiation and bonding, which is simple to use, ffis variable width and depth trenches, shows excellent planarization, provides excellent RX isolation, and can be used to provide very shallow, isolated active areas is described herein.

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MOTOROLA INC. Technical Developments Volume 18 March 1993

A NEW ISOLATION PROCESS FOR VARIABLE WIDTH AND DEPTH TRENCHES BY USING A GLASS FRITIPOWDER

by Henry G. Hughes, Juergen Foeretner, Marilyn J. Stuckey, and Julia A. Jones

INTRODUCTION

  The ability to form variable width and variable depth isolation regions on the same device has been diicult to achieve in high density semiconductor devices. A new method for planatiation and bonding, which is simple to use, ffis variable width and depth trenches, shows excellent planarization, provides excellent RX isolation, and can be used to provide very shallow, isolated active areas is described herein.

EXPERIMENTAL

   A frit glass (powder) is mixed with binder, such as terpineol, a polymer, or photoresist to form a paste. The paste can be applied by silkscreening, spinning, spraying, or by spatula to the device wafer containing trenches to be isolated. It can also be applied to a handle wafer if one is employed. Various glass can be used, depending upon the process temperatures the devices see (i.e. glass enameliig 2 1000°C for high temperature processes, or glasses enameling at 500°C to be used after metallization).

The major process steps are shown in Figure 1, and involve:

1. Etching trenches and lining with a thin dielectric liner;
2. Coating the device wafer that contains the isolation regions and a handle (optional) wafer with a powdered glass (such as a glass plus binder);
3. Placing the wafer containing the applied glass in an oven or furnace to bum off the binder;
4. Firing the glass to melt and effect a bond between the two wafers;
5. Grinding/polishing back to the isolated region; and
6. Building the device in the active region.

  The wafers can be bonded in a furnace or what is referred to as a DAP wafer bonder (a wafer is bonded in vacuum under pressure) at a temperature that corre- sponds to the glass enameling (melting) te...