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Improving STI Gap Fill and Nitride Clipping Using Thermally Decomposed Polymers for STI-Related Applications

IP.com Disclosure Number: IPCOM000084984D
Publication Date: 2005-Mar-02
Document File: 3 page(s) / 179K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that applies thermally decomposed polymers (TDP) to reduce the effective CD of the STI trench. Benefits include improving the gap fill and nitride clipping, and avoiding the high temperature annealing step.

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Improving STI Gap Fill and Nitride Clipping Using Thermally Decomposed Polymers for STI-Related Applications

Disclosed is a method that applies thermally decomposed polymers (TDP) to reduce the effective CD of the STI trench. Benefits include improving the gap fill and nitride clipping, and avoiding the high temperature annealing step.

Background

Currently, high density plasma (HDP) is used for STI isolation. However, increased aspect ratios and narrowing diffusion CDs limit the usefulness of this approach. Narrower diffusion CDs limit the amount of nitride clipping that is tolerated by the CMP (see Figure A). This in turn limits the gap fill capability of the HDP process; the factors which improve gap fill generally degrade nitride clipping.

There are alternate technologies to HDP; however, they each have their own individual issues: 

§         SACVD. Surface sensitivity issues result in poor gap fill with the current trench liner. Also, this approach requires a high temperature anneal to achieve the appropriate wet etch rates.

§         SOD. The anneals required to achieve the appropriate wet etch rates result in substrate silicon consumption; this negatively impacts device performance.

§         ALD. The run rate required to achieve gap fill is economically unfeasible.  It is also a very conformal film, which may lead to weak seam issues.

General Description

The following are the process steps for creating the disclosed method:

1.      Apply a layer of TDP (by spin-coating) on to the pattern wafer (see Figure 1) to fill the deep trenches (see Figure 2).

2.      Use plasma etching to remove the TDP on the top of the patterns, then further etch the TDP into the trench region as shown in Figure 3.

3.      The cap layer is formed on the top of the TDP in the trench after plasma etching. The position of the layer in the tre...