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Semiconductor Integrated Display With Anodized Light Barrier

IP.com Disclosure Number: IPCOM000045931D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 38K

Publishing Venue

IBM

Related People

Lowe, AC: AUTHOR [+2]

Abstract

An electrochromic or other passive matrix display has an array of display electrodes integrated on a semiconductor substrate. The semiconductor substrate includes an array of switching devices which are connected by via hole metallurgy through insulating layers to corresponding electrodes. Photoconduction in the semiconductor substrate is prevented by a metallic, preferably aluminum, light barrier. The surface of the light barrier is oxidized to provide an upper level of insulation and to prevent it shorting to the vias. The electrode metallurgy is then deposited directly on the oxidized layer. The light barrier is also employed as a mask for opening the vias through the underlying material by plasma etching.

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Semiconductor Integrated Display With Anodized Light Barrier

An electrochromic or other passive matrix display has an array of display electrodes integrated on a semiconductor substrate.

The semiconductor substrate includes an array of switching devices which are connected by via hole metallurgy through insulating layers to corresponding electrodes. Photoconduction in the semiconductor substrate is prevented by a metallic, preferably aluminum, light barrier. The surface of the light barrier is oxidized to provide an upper level of insulation and to prevent it shorting to the vias.

The electrode metallurgy is then deposited directly on the oxidized layer. The light barrier is also employed as a mask for opening the vias through the underlying material by plasma etching.

The drawings show various stages in the formation of the integrated display structure. Fig. 1 shows a silicon substrate 1 provided with aluminum pads 2 connecting the switching devices (not shown) and a top insulating layer 3 of silicon dioxide.

In Fig. 2, a 2 micron layer of polyimide 4 is deposited over the entire display surface and is followed by a 0.2-micron layer 5 of aluminum.

A layer of photoresist is applied over the aluminum and is exposed and developed to form a mask for the production of the via holes 7. These are formed by, firstly, wet etching the aluminum in orthophosphoric acid. Then, the polyimide layer 4 is plasma etched in oxygen, and, finally, the silicon dioxide layer 3 is plasma etched in carbon tetrafluoride and oxygen. The aluminum layer 5 itself acts as a self-- aligned mask for the plasma etching steps.

After removal o...