Device isolation technology on semiconductor substrate

Abstract

A method of forming device isolation regions on a trench-formed silicon substrate and removing residual carbon therefrom includes providing a flowable, insulative material constituted by silicon, carbon, nitrogen, hydrogen, oxygen or any combination of two or more thereof; forming a thin insulative layer, by using the flowable, insulative material, in a trench located on a semiconductor substrate wherein the flowable, insulative material forms a conformal coating in a silicon and nitrogen rich condition whereas in a carbon rich condition, the flowable, insulative material vertically grows from the bottom of the trenches; and removing the residual carbon deposits from the flowable, insulative material by multi-step curing, such as O2 thermal annealing, ozone UV curing followed by N2 thermal annealing.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to the field of semiconductor integrated circuit manufacturing and, more particularly to a method of forming device isolation regions on a semiconductor substrate by using PECVD and to a method of removing residual carbon deposits from an intermediate semiconductor device structure.[0003]2. Description of the Related Art[0004]Integrated circuits fabricated on semiconductor substrates for large scale integration require multiple levels of metal interconnections to electrically interconnect the discrete layers of semiconductor devices on the semiconductor chips. Today several million devices can be fabricated in a single chip, for example, the mega-bit memory chips which are commonly used today in personal mobile and in other applications.[0005]Devices of semiconductor typically include semiconductor substrate and a plurality of adjacent, active devices that are electrically isolated from one...

AI Technical Summary

Benefits of technology

The present invention provides methods for forming device isolation and removing residual carbon deposits at low temperatures. The methods allow for control over filling and conformal coating in trenches and can be used to form field insulative materials of different sizes. The invention also includes a multi-step curing process to remove residual carbon deposits from the flowable insulating material. The technical effects of the invention include improved device isolation and reduced carbon deposits, which can enhance the performance and reliability of integrated circuits.

Problems solved by technology

The above described conventional LOCOS technique has a number of disadvantages, which become rather unacceptable when attempting to apply this technique to the fabrication of sub-micron devices.

First, the oxidization of silicon happens not only in the vertical direction but also in the horizontal direction.

Secondly, due to the stresses caused by the bird's beak effect, a part of nitride hard mask in the compressed regions of silicon nitride layer diffuses to adjacent tensile strained regions at the interface of the pad oxide layer and the substrate, and forms a silicon-nitride-like region.

While trench isolation provides these advantages, undesirable voids can be formed in the silicon dioxide material as the trench fills because the silicon dioxide material tends to stick to the sides and sidewalls of the trench, rather than evenly filling the trench from the bottom to the top.

Carbon in the deposited film causes the film to be soft and porous, which makes the deposited film unstable during subsequent processing, such as etching processes.

Also, if the flowable oxide material is used to fill isolation trenches within the semiconductor substrate, the carbon cause device degradation.

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