Polygonal Trench Isolation for Self-Aligned Contacts

Solution Overview

Problem

Conventional trench isolation structures in semiconductor devices require additional photomasks to define contact holes, leading to increased complexity and cost, and suffer from bias coupling phenomena affecting semiconductor element operations.

Innovation Solution

A trench isolation structure with a polygonal trench and insulating material, featuring a polygon top-side contact structure that matches the trench shape, allowing self-aligned contact hole formation without additional photomasks and preventing bias coupling by grounding the top-side contact structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If additional photomasks are used to define contact holes, then contact structure positioning precision is improved, but process complexity and manufacturing cost increase

Engineering Contradiction:

Improvecontact structure positioning precisionVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent performs preliminary action by forming the contact hole pattern concurrently with the trench isolation structure during the same etching process, rather than defining contact holes separately with additional photomasks later. This preliminary integration eliminates the need for extra photomask steps while maintaining positioning precision, as the contact holes are created in the same polygonal pattern as the trench isolation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent merges the formation of trench isolation structures and contact holes into a single integrated process step. Both structures are formed simultaneously using the same polygonal trench pattern and etching conditions, combining what were previously separate fabrication steps into one unified operation, thereby reducing process complexity and eliminating additional photomask requirements.

Inventive Principle:

Principle #5Merging (Combining)

2Manufacturing precision

If additional photomasks are used to define contact holes, then contact structure positioning precision is improved, but manufacturing cost increases

Engineering Contradiction:

Improvecontact structure positioning precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent merges the formation of trench isolation structures and contact holes into a single integrated process step. Both structures are formed simultaneously using the same polygonal trench pattern and etching conditions, combining what were previously separate fabrication steps into one unified operation, thereby reducing process complexity and eliminating additional photomask requirements.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent applies universality by using a single polygonal trench pattern and etching process to achieve multiple functions simultaneously: creating both the trench isolation structures and the contact holes. This multi-functional approach eliminates the need for separate photomasks and process steps that would otherwise be required for contact hole definition, reducing manufacturing cost while maintaining precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If conventional top-side contact structure is used, then electrical isolation is achieved, but device area is increased due to additional photomask requirements

Engineering Contradiction:

Improveelectrical isolationVSAvoiddevice area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the formation of trench isolation structures and contact holes into a single integrated process step. Both structures are formed simultaneously using the same polygonal trench pattern and etching conditions, combining what were previously separate fabrication steps into one unified operation, thereby reducing process complexity and eliminating additional photomask requirements.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10347524B2Trench isolation structures and methods for forming the same

Publication Date: 2019.07.09 VANGUARD INTERNATIONAL SEMICONDUCTOR CORPORATION

AI summary

A trench isolation structure is provided. The trench isolation structure includes a substrate. A polygonal trench is disposed in the substrate. An insulating material is disposed in the polygonal trench, and a polygon top-side contact structure is disposed in the polygonal trench and surrounded by the insulating material. The polygon top-side contact structure has the same shape as the polygonal trench from a top view. A method for forming the trench isolation structure is also provided.