Browse Prior Art Database

Terminal via Etch Process for 16 Mbits DRAM Chips

IP.com Disclosure Number: IPCOM000118904D
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 141K

Publishing Venue

IBM

Related People

Leverd, F: AUTHOR

Abstract

The standard Terminal Via (TV) process has a final metallurgy characterized by: gold wires and a vertical profile above the pads through the SiO2/Si3N4 passivation layer.

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This is the abbreviated version, containing approximately 95% of the total text.

Terminal via Etch Process for 16 Mbits DRAM Chips

      The standard Terminal Via (TV) process has a final metallurgy
characterized by: gold wires and a vertical profile above the pads
through the SiO2/Si3N4 passivation layer.

      The conventional C4 technique includes a metal evaporation step
to produce a Cr/Cr-Ar/Cu/Sn final metallurgy.  For this step, TVs
must have a positive slope (60-70 degrees), instead of a vertical
profile for  better metal adhesion reasons.  To that end, a new etch
process has been  developed, which is particularly suitable for use
with the anisotropic  etch chamber of a LAM 4520 system, equipment
sold by LAM Research Corp.,  Fremont, CA, USA.  The operating
condition of the new etch process is given below:
  First step:
  Pressure             : 300 mTorr
  Power                : 1500 W
  Spacing              : 1.05 cm
  Ar flow              :  300 sccm
  CF4 flow             :   80 sccm
  CHF3 flow            :   40 sccm
  Upper electrode temp.:   40 C
  Lower electrode temp.:    0 C
  Backside He pressure :   10 Torr

      In the second step, oxygen is added.  In the table below, only
the parameters that have been changed are indicated:
  Pressure :  200 mTorr
  Power    : 1000 W
  Ar flow  :  200 sccm
  CHF3 flow:   45 sccm
  O2 flow  :   40 sccm

      The figure shows a photograph of the tapered (about 6...