Isolation Structure Fabrication Using Directional Beam Trench Filling

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Solution Overview

Problem

Existing methods for forming isolation structures in semiconductor devices face challenges in achieving consistent trench depth, leading to insufficient dielectric material in some trenches, which can result in device leakage due to insufficient isolation.

Innovation Solution

A directional deposition process using gas cluster ion beam to fill recesses with silicon nitride dielectric material, followed by controlled polishing from the backside to form isolation structures with precise depth and efficient interconnect formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional trench filling methods are used, then the filling process is simpler, but the trench depth control is inconsistent leading to insufficient dielectric material

Engineering Contradiction:

Improvetrench depth controlVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent performs dielectric material deposition from the backside of the substrate rather than from the frontside, adding a dimensional aspect to the filling process. This backside deposition approach allows for better depth control as the material is deposited through the trench opening from the opposite direction, ensuring consistent filling to the required depth regardless of trench variation

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent performs preliminary trench depth verification and adjustment before the final dielectric material deposition. The method includes forming the trench to a predetermined depth, verifying the depth, and making adjustments if necessary before depositing the dielectric material, ensuring that the trench is ready for consistent filling

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If directional beam deposition is used, then the dielectric material distribution is more uniform, but the deposition process is more complex

Engineering Contradiction:

Improvedielectric material distribution uniformityVSAvoiddeposition process ease

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces conventional thermal or chemical vapor deposition methods with a directional beam deposition process. The beam deposition method uses a focused beam to deposit dielectric material in a highly directional manner, providing superior uniformity and control over material distribution within the trench structure

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The directional beam deposition process delivers dielectric material with different properties to different locations within the trench. The beam can be focused to provide enhanced material density and uniformity specifically within the trench region while minimizing deposition on surrounding areas, achieving local quality optimization

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If polishing is performed to control isolation structure depth, then the depth precision is improved, but the substrate material is removed

Engineering Contradiction:

Improveisolation structure depth precisionVSAvoidsubstrate material removal

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The patent incorporates a stop layer within the trench structure that automatically halts the polishing process when reached. This self-service mechanism ensures that the isolation structure depth is precisely controlled without requiring complex real-time monitoring or risking over-polishing, as the stop layer provides a physical endpoint that prevents further substrate removal

Inventive Principle:

Principle #25Self-service

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

The method ensures well-controlled isolation structure depth with minimal sidewall deposition, effectively isolating neighboring devices and enabling efficient formation of interconnect structures, reducing leakage and enhancing device performance.

Implementation Method 1

utilizing gas cluster ion beam to deposit the dielectric material

Methodology Applied

Scientific EffectGas cluster ion beam deposition: Physical Vapour Deposition

Implementation Method 2

polishing, from a second side of the substrate, a first remaining portion of the substrate until a bottom surface of the isolation structure is exposed

Methodology Applied

Scientific EffectMechanical polishing: Abrasion

Data Source

PatentUS12538560B2Methods for fabricating isolation structures using directional beam process

Publication Date: 2026.01.27 TOKYO ELECTRON LTD

AI summary

A method for fabricating semiconductor devices is disclosed. The method includes forming, on a first side of a substrate, a first stack and a second stack. The method includes etching, from the first side, a portion of the substrate interposed between the first and second stacks to form a recess. The method includes filling the recess with a dielectric material to form an isolation structure. The method includes forming, on the first side, one or more first interconnect structures over the first and second stacks. The method includes removing, from a second side of the substrate opposite to the first side, a remaining portion of the substrate. The method includes forming a via structure extending through at least the isolation structure. The method includes forming, on the second side, one or more second interconnect structures.