Dual Trench Isolation Structures for Semiconductor Devices

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Solution Overview

Problem

Conventional techniques for forming deep and shallow isolation regions in semiconductor devices face challenges such as defect detection issues, single crystal spike defects, and process control problems due to dependence on deep trench pattern density, leading to variability in planarity and current leakage.

Innovation Solution

The implementation of a semiconductor isolation structure with a deep trench isolation and a shallow trench isolation, where the deep trench has sidewalls extending from the shallow trench and is lined with a multilayer dielectric including an etch stop layer, and a filler material is used within the deep trench, allowing for independent formation and defect detection, eliminating single crystal spike defects and improving process control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If conventional techniques form deep trenches followed by shallow trenches, then deep isolation regions are achieved, but defect detection and assessment is prevented and single crystal spike defects occur

Engineering Contradiction:

Improvedepth of isolation regionVSAvoiddefect detection capability

Core Design Contradiction:

Length of stationary objectVSReliability

Solution Approach 1:

The isolation structure is divided into two independent trench systems: deep trenches formed first to provide deep isolation, and shallow trenches formed later to provide shallow isolation. This segmentation allows each trench type to be optimized independently and enables defect detection in the shallow trenches without being compromised by the deep trench structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The conventional sequence is inverted: instead of forming deep trenches first and then shallow trenches (which prevents defect detection), the patent forms shallow trenches first and then deep trenches. This inversion allows subsequent detection and assessment of defects in the shallow isolation regions while maintaining deep isolation capability.

Inventive Principle:

Principle #13The other way round (Inversion)

2Length of stationary object

If conventional techniques form deep trenches first, then shallow trenches are formed, but this causes single crystal spikes to puncture the extrinsic base and cause current leakage

Engineering Contradiction:

Improvedepth of isolation regionVSAvoidcurrent leakage from single crystal spikes

Core Design Contradiction:

Length of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The shallow trenches are formed in advance with proper lining and filling before the deep trenches are etched. This preliminary action ensures that the shallow isolation structure is already in place and protected, preventing single crystal spikes from forming and puncturing the extrinsic base during subsequent processing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A multilayer dielectric lining is introduced as an intermediary structure between the trench walls and the semiconductor substrate. This lining includes an etch stop layer and dielectric layers that prevent direct contact between the trench walls and the substrate, eliminating the formation of single crystal spikes that would otherwise puncture the extrinsic base.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If shallow trench formation is dependent on deep trench pattern density, then both isolation types are achieved, but process control problems and planarity variability occur

Engineering Contradiction:

Improveability to form both deep and shallow isolationVSAvoidplanarity of shallow isolation regions

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The formation process is segmented into independent stages: deep trenches are formed and filled first, then shallow trenches are formed separately. This segmentation decouples the pattern density dependencies, allowing shallow trench formation to proceed with consistent process parameters regardless of the deep trench pattern density, thereby improving planarity control.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the process parameters for shallow trench formation to be independent of deep trench pattern density. By adjusting etch conditions, filling parameters, and planarization processes, the shallow trench formation achieves consistent planarity across different deep trench patterns, resolving the manufacturing precision issue.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11049932B2Semiconductor isolation structures comprising shallow trench and deep trench isolation

Publication Date: 2021.06.29 GLOBALFOUNDRIES US INC

AI summary

The present disclosure relates to isolation structures for semiconductor devices and, more particularly, to dual trench isolation structures having a deep trench and a shallow trench for electrically isolating integrated circuit (IC) components formed on a semiconductor substrate. The semiconductor isolation structure of the present disclosure includes a semiconductor substrate, a shallow trench isolation (STI) disposed over the semiconductor substrate, a deep trench isolation (DTI) with sidewalls extending from a bottom surface of the STI and terminating in the semiconductor substrate, a multilayer dielectric lining disposed on the sidewalls of the DTI, the multilayer dielectric lining including an etch stop layer positioned between inner and outer dielectric liners, and a filler material disposed within the DTI.