Browse Prior Art Database

Making Conductive Platinum Membranes Across Holes in Silicon Without the Use of Masks

IP.com Disclosure Number: IPCOM000087820D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Geldermans, P: AUTHOR

Abstract

This article shows a method for forming conductive platinum (Pt) membranes across holes at the bottom of cavities in a silicon substrate. The method uses the phenomenon that Pt, evaporated over SiO(2), has a much poorer adhesion than Pt evaporated over bare Si.

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Making Conductive Platinum Membranes Across Holes in Silicon Without the Use of Masks

This article shows a method for forming conductive platinum (Pt) membranes across holes at the bottom of cavities in a silicon substrate. The method uses the phenomenon that Pt, evaporated over SiO(2), has a much poorer adhesion than Pt evaporated over bare Si.

The steps of the method are as follows:

1. Using a silicon substrate 1 (Fig. 1), oxidize Si (100) or (110) on both sides to form SiO(2) layers 2 approximately 8000 angstroms thick.

2. Etch cavity 3 through substrate 1, using conventional photo-lithographic techniques, and buffered HF (hydrofluoric acid) and pyrocatechol etching, using lower layer 2 of SiO(2) as an etch stop.

3. As shown in Fig. 2, evaporate a 5000 angstrom layer 4 of Pt over upper layer 2 and in cavity 3.

4. Submerge substrate 1 in buffered HF or warm water.

In the early stages of the last step, the Pt floats away from upper layer 2 of SiO(2), but not from wall 5 of the cavity 3, and not from portion 6 of bottom layer 2 of SiO(2) at the bottom of cavity 3, since it is held in place by the Pt on wall 5.

Continued etching removes all of bottom layer 2 of SiO(2) from substrate 1 and exposes the Pt which was atop portion 6 of layer 2, providing the structure shown in Fig. 3.

Alternatively, if photoresist was applied after float-away of the Pt, the resulting structure would be that shown in Fig. 4.

Using the above approach, platinum is deposited precisely and...