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Polyimide Nitride Isolation

IP.com Disclosure Number: IPCOM000044497D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 89K

Publishing Venue

IBM

Related People

Thiel, KP: AUTHOR [+3]

Abstract

Deep dielectric isolation is formed by reactive ion etching trenches in a monocrystalline silicon substrate, plasma depositing SiO2 and Si3N4 layers, and filling the trenches with polyimide. The method steps are as follows: 1. Form photoresist mask 4 on substrate with silicon wafer 1, silicon dioxide/silicon nitride layers 2, 3 and contact opening 5 (Fig. 1). 2. CF4 reactively ion etch (RIE) silicon dioxide/silicon nitride layers 2, 3 to open the areas where trenches are desired. CBrF3 reactively ion etch to form trenches 6 in wafer 1 and bake photoresist 4 at about 300 C (Fig. 2). 3. Form silicon dioxide/silicon nitride double layer 7 with a thickness of about 200 nm by plasma deposition and apply 1.5 mm polyimide layer 8 (Fig. 3). 4.

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Polyimide Nitride Isolation

Deep dielectric isolation is formed by reactive ion etching trenches in a monocrystalline silicon substrate, plasma depositing SiO2 and Si3N4 layers, and filling the trenches with polyimide. The method steps are as follows: 1. Form photoresist mask 4 on substrate with silicon wafer 1, silicon dioxide/silicon nitride layers 2, 3 and contact opening 5 (Fig. 1). 2. CF4 reactively ion etch (RIE) silicon dioxide/silicon nitride layers 2, 3 to open the areas where trenches are desired. CBrF3 reactively ion etch to form trenches 6 in wafer 1 and bake photoresist 4 at about 300 C (Fig. 2). 3. Form silicon dioxide/silicon nitride double layer 7 with a thickness of about 200 nm by plasma deposition and apply 1.5 mm polyimide layer 8 (Fig. 3). 4. CF4 reactively ion etch to remove polyimide 8 and silicon dioxide/silicon nitride double layer 7. O2 reactively ion etch to remove polyimide 8 and photoresist 4 to the level of contacts 5 being open again (Fig. 3). 5. Bake polyimide at about 400 C. Clean surface, using buffered hydrofluoric acid for subsequent metallization (Fig. 4). The advantages of this process are: 1. Butting of devices to isolation is possible, increasing the density by up to three times. As a result of this and the reduction in the capacities of collector/substrate, base/ isolation and emitter/isolation, there is an increase in performance. 2. Easy and cheap trench refill; trench shape is uncritical. 3. Planar process; no additiona...