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Method of Forming Self-aligned Shallow Trench Liner ReOx

IP.com Disclosure Number: IPCOM000198589D
Publication Date: 2010-Aug-10
Document File: 5 page(s) / 91K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method is provided to form a self-aligned shallow trench liner ReOx. The method limits formation of divots in Shallow Trench Isolation (STI) oxide adjacent to RX edges. The divot formation is limited by omitting nitride liner deposition which causes formation of STI divots.

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Method of Forming Self-aligned Shallow Trench Liner ReOx

Disclosed is a method of forming a self-aligned shallow trench liner ReOx.

Divots occur in Shallow Trench Isolation (STI) oxide adjacent to RX edges. These divots can fill with PC poly causing the poly to wrap around the corner of the device and thus degrade the device Vt characteristics. Limiting divot formation improves device Vt characteristics and defect yields.

The method disclosed herein, limits the divot formation in STI oxide adjacent to RX edges. The divot formation is limited by omitting nitride liner deposition which causes divots in the STI oxide adjacent to the RX edges. Here, the STI oxide is etched into a wafer and a liner oxide is formed in the STI oxide, as illustrated in Fig. 1a - Fig. 1c. Subsequently, a multi-step High Density Plasma (HDP) oxide deposition process is used with a wet HF etch back between oxide depositions to fill the high aspect ratio STI, as illustrated in Fig. 1d. The Si locations exposed by the removal of liner oxide during the HDP HF etch back step is then re-oxidized to form a self-aligned shallow trench liner ReOx as illustrated in Fig. 1e and Fig. 1f. Thereafter, a second HDP oxide deposition process is performed followed by planarizing the STI. This is illustrated in Fig. 1g and Fig.1h respectively.

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Figure 1a

Figure 1b

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Figure 1c

Figure 1d

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