Tapered Through Silicon Via Fabrication via Spacer Etching

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Solution Overview

Problem

The existing through silicon via (TSV) fabrication methods face issues with vertical-profile-induced liner overhang and metal gap fill voiding, leading to incomplete filling of via holes and quality problems such as tear drop voids and seam voids during the conductive material filling process.

Innovation Solution

A method involving the formation of a patterned hard mask and a spacer-shaped structure on the substrate, followed by etching to create a via hole with a tapered shape, where the opening size at the upper portion is greater than at the lower portion, allowing for a spacer-shaped structure with a specific etch rate to prevent overhang and enable complete filling with conductive material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a vertical-profile via hole is formed by conventional etching methods, then the via hole can be formed efficiently, but liner overhang occurs during filling process

Engineering Contradiction:

Improvevia hole formation efficiencyVSAvoidfilling quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent transitions from forming a vertical via hole to forming a tapered via hole with an enlarged opening. This dimensional change in the via hole geometry allows the opening to be larger than the bottom, preventing liner overhang during the filling process while maintaining formation efficiency through the spacer-based etching method.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent forms a spacer structure on the sidewall of the opening before etching the via hole. This preliminary action creates a template that defines the tapered profile, ensuring that the via hole will have an enlarged opening that prevents overhang during subsequent filling operations.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If a vertical-profile via hole is formed, then the structure is simple to manufacture, but metal gap fill voiding occurs

Engineering Contradiction:

Improvevia hole fabrication simplicityVSAvoidfilling completeness

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the via hole geometry from vertical to tapered with an enlarged opening. This dimensional modification ensures that the opening is wider than the bottom, preventing metal gap fill voiding by allowing complete filling without overhang, while maintaining ease of manufacture through the spacer-based formation process.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If a tapered via hole with enlarged opening is formed, then liner overhang is prevented, but the etching process becomes more complex

Engineering Contradiction:

Improveoverhang preventionVSAvoidetching process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces a spacer structure as an intermediary element that simplifies the etching process. The spacer is formed on the sidewall and serves as a template that automatically defines the tapered profile during etching, eliminating the need for complex direct etching control while achieving precise overhang prevention.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The spacer structure is formed preliminarily before the via hole etching. This preliminary formation of the spacer provides a built-in template that guides the etching process to create the desired tapered profile, simplifying the overall process by pre-defining the geometry rather than requiring complex real-time etching control.

Inventive Principle:

Principle #10Preliminary action

4Reliability

If a tapered via hole is formed with spacer structure, then metal gap fill voiding is prevented, but the fabrication steps increase

Engineering Contradiction:

Improvefilling qualityVSAvoidfabrication steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The spacer structure acts as an intermediary that enables reliable filling by preventing overhang and voiding. Although it adds a fabrication step, the spacer serves multiple functions: defining the tapered profile, preventing overhang, and ensuring complete filling, thereby improving reliability while adding only one essential process step.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 effectively prevents liner overhang and metal gap fill voiding, ensuring better filling quality and consistency of the via holes, thereby improving the overall TSV structure's integrity and performance.

Implementation Method 1

the spacer-shaped structure and the substrate are etched through the opening to form a via hole in the substrate

Methodology Applied

Scientific EffectEtching:

Data Source

PatentUS8609529B2Fabrication method and structure of through silicon via

Publication Date: 2013.12.17 UNITED MICROELECTRONICS CORP

AI summary

A method of fabricating a through silicon via (TSV) structure, in which, a patterned mask is formed on a substrate, the patterned mask has an opening, a spacer-shaped structure is formed on a sidewall of the opening, and a via hole having a relatively enlarged opening is formed by etching the spacer-shaped structure and the substrate through the opening after the spacer-shaped structure is formed. A TSV structure, in which, a via hole has an opening portion and a body portion, the opening portion is a relatively enlarged opening and has a tapered shape having an opening size of an upper portion greater than an opening size of a lower portion.