Top Via Height Control via Selective Metal Growth

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Solution Overview

Problem

In semiconductor devices, maintaining uniform height and shape of top via structures over metal lines is challenging due to the complexity of interconnect layers and the need for precise vertical electrical connections, which affects the performance and reliability of integrated circuits.

Innovation Solution

A method involving forming a metal interconnect layer, patterning with a hardmask, overfilling with a sacrificial material, selectively removing portions to create via openings, and using selective metal growth to form vias with controlled taper angles, ensuring uniformity and accuracy in via formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional via formation processes are used, then via structures can be formed, but uniform height and shape control of top via structures cannot be achieved

Engineering Contradiction:

Improvevia height and shape uniformityVSAvoidinterconnect layer complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The via formation process is segmented into distinct stages: forming sacrificial material to overfill the via opening, selectively removing portions to create the via opening, and using selective metal growth to form the via. This segmentation allows independent control of each parameter (height, shape, taper angle) at different process stages, resolving the contradiction between achieving uniform via structures and managing process complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Sacrificial material is deposited in advance to overfill the via opening before the actual via formation. This preliminary action establishes a reference height that guides subsequent selective removal and metal growth processes, ensuring uniform via height and shape while simplifying the overall process control.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If selective metal growth is used to form vias, then via height uniformity is improved, but process complexity increases

Engineering Contradiction:

Improvevia height controlVSAvoidfabrication process simplicity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

A sacrificial material layer serves as an intermediary between the via opening definition and the final metal via formation. This intermediary structure enables selective metal growth to occur with precise height control while the sacrificial material is subsequently removed, effectively mediating between the patterning step and the metal deposition step to simplify overall manufacturing.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The process utilizes parameter changes in the selective metal growth step, where growth conditions are controlled to achieve specific taper angles (positive or negative) and uniform heights. By changing physical and chemical parameters during metal growth, precise via dimensions are achieved without requiring complex equipment or multiple processing steps.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If uniform via dimensions are maintained, then interconnect performance is improved, but fabrication variations increase

Engineering Contradiction:

Improveinterconnect performanceVSAvoidfabrication consistency

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The selective metal growth process incorporates feedback mechanisms where the growth rate and termination are controlled based on the presence of the sacrificial material and hardmask structures. This feedback ensures that vias achieve uniform dimensions regardless of minor fabrication variations, improving both reliability and manufacturing precision simultaneously.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The sacrificial material is deposited to overfill the via opening with excess material beforehand, creating a cushion that compensates for potential fabrication variations. This prior cushioning ensures that even if there are variations in earlier patterning steps, the final via dimensions remain uniform, improving both reliability and manufacturing precision.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

This approach allows for the formation of vias with precise taper angles, improving the uniformity and accuracy of interconnect structures, enhancing the performance and reliability of semiconductor devices by maintaining consistent via dimensions and reducing fabrication variations.

Implementation Method 1

forming a via on the metal interconnect layer in the via opening by a selective metal growth process

Methodology Applied

Scientific EffectSelective metal growth: Deposition (physical)

Data Source

PatentUS20230178429A1Accurate metal line and via height control for top via process

Publication Date: 2023.06.08 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A method of manufacturing an interconnect structure for a semiconductor device is provided. The method includes forming a metal interconnect layer on a substrate. The method includes forming a hardmask on the metal interconnect layer, patterning the metal interconnect layer and hardmask, forming a sacrificial material layer to overfill the patterned metal interconnect layer and hardmask, and selectively removing a portion of the sacrificial layer and the hardmask to form a via opening. The method also includes forming a via on the metal interconnect layer in the via opening by a selective metal growth process.