Browse Prior Art Database

Stepped Via Hole Etching

IP.com Disclosure Number: IPCOM000084258D
Original Publication Date: 1975-Oct-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Hayunga, CP: AUTHOR [+2]

Abstract

Fig. 1 shows a zero overlap via hole 4 in quartz 6 containing a first metal land 8. Off-incidence evaporation can cause crack or discontinuity in the second metal strip 10, resulting in a high-resistance path. This crack is due to the "shadow" effect caused by the steep step at the top of the via hole 4. Also shown is the angle of evaporation 12.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Stepped Via Hole Etching

Fig. 1 shows a zero overlap via hole 4 in quartz 6 containing a first metal land 8. Off-incidence evaporation can cause crack or discontinuity in the second metal strip 10, resulting in a high-resistance path. This crack is due to the "shadow" effect caused by the steep step at the top of the via hole 4. Also shown is the angle of evaporation 12.

One way to produce quartz vias with profiles that are contoured to assure the continuity of the evaporated metal conductors, is to reduce the steep step at the top of the via hole.

First the hole 4 is etched for approximately seventy-five percent of the quartz thickness, using 5:1 BHF at 31 degrees C or 17K angstroms (Fig. 2) in order to define the resist.

The approximate remaining twenty-five percent of the etching is done in 15:1 BHF at 25 degrees C or 5.2 K angstroms (Fig. 3). This increased time causes controlled resist breakdown at the top of the hole 4, allowing the top of the hole to be etched larger and with smoother sloped sides.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text objects]