Hybrid Gap-Fill STI Formation for High Aspect Ratio Voids

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Solution Overview

Problem

Conventional gap-filling methods for shallow trench isolation (STI) regions fail to effectively fill high aspect ratio openings without forming voids or weak seams, leading to bridging and shorting issues in integrated circuits, especially as aspect ratios exceed 7.0.

Innovation Solution

A method involving conformal deposition of dielectric material, followed by a treatment to break bonds, a steam anneal, and a dry anneal to activate oxygen atoms and form strong bonds, eliminating voids and seams, allowing for the formation of STI regions with aspect ratios greater than 7.0.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional gap-filling methods (HDP or HARP) are used to fill STI openings, then the filling process is simple and fast, but voids are formed when aspect ratio exceeds 7.0

Engineering Contradiction:

Improvefilling qualityVSAvoidaspect ratio capability

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The gap-filling process is divided into multiple sequential deposition steps rather than a single filling operation. Each step deposits a portion of the dielectric material, allowing the aspect ratio capability to be effectively increased beyond 7.0 by progressive filling, thereby resolving the contradiction between filling quality and aspect ratio capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A liner layer is deposited on the sidewalls before the main gap-filling process. This preliminary action creates a foundation that prevents void formation during subsequent filling steps, enabling high aspect ratio filling while maintaining filling quality.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If HARP is used to fill high aspect ratio gaps, then conformal oxide is deposited, but weak seams are formed due to inactive C2H5 terminals

Engineering Contradiction:

Improveseam strengthVSAvoidmechanical strength

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The chemical composition and reactivity of the dielectric material is modified by introducing reactive species during deposition. This parameter change activates the C2H5 terminals, transforming them from inactive to reactive states that form strong bonds, thereby resolving the contradiction between seam strength and mechanical strength.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The dielectric material is deposited with incorporated reactive species or modified chemical composition, creating a composite structure with enhanced bonding capability. This composite approach strengthens the seams by activating chemical terminals, resolving the contradiction between seam integrity and mechanical strength.

Inventive Principle:

Principle #40Composite materials

3Manufacturing precision

If multiple deposition steps are performed to fill high aspect ratio openings, then voids are eliminated, but process complexity and cost increase

Engineering Contradiction:

Improvevoid eliminationVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Multiple deposition steps are merged into a coordinated sequence with optimized intermediate treatments. The process combines deposition, in-situ treatments, and annealing steps that work synergistically to eliminate voids while minimizing overall process complexity through integration and optimization.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The deposition process is made continuous with in-situ treatments performed between deposition steps without breaking the process flow. This continuous action maintains filling quality by preventing void formation while reducing process complexity by eliminating intermediate handling and setup steps.

Inventive Principle:

Principle #20Continuity of useful action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables the formation of STI regions with high aspect ratios without voids or seams, improving mechanical strength and reducing the risk of bridging and shorting in integrated circuits, suitable for 40 nm technology and below.

Implementation Method 1

performing a conformal deposition method to fill a dielectric material into the opening

Methodology Applied

Scientific EffectConformal deposition: Chemical Vapour Deposition

Implementation Method 2

performing a first treatment on the dielectric material, wherein the first treatment provides an energy high enough for breaking bonds in the dielectric material

Methodology Applied

Scientific EffectBond breaking through energy input:

Implementation Method 3

performing a steam anneal on the dielectric material

Methodology Applied

Scientific EffectSteam annealing: Annealing

Implementation Method 4

performing a dry anneal after the steam anneal

Methodology Applied

Scientific EffectDry annealing: Annealing

Data Source

PatentUS8546242B2Hybrid gap-fill approach for STI formation

Publication Date: 2013.10.01 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method of forming a shallow trench isolation region is provided. The method includes providing a semiconductor substrate comprising a top surface; forming an opening extending from the top surface into the semiconductor substrate; performing a conformal deposition method to fill a dielectric material into the opening; performing a first treatment on the dielectric material, wherein the first treatment provides an energy high enough for breaking bonds in the dielectric material; and performing a steam anneal on the dielectric material.