Via Plug Without Barrier Material for Finer IC Line Widths

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Solution Overview

Problem

Existing integrated circuit (IC) technologies face challenges in achieving finer line widths and spacings due to the need for barrier materials in via connections, which can hinder the efficiency of metal layer connections and increase complexity.

Innovation Solution

The implementation of a via plug without barrier material, using conductive materials like aluminum (Al) and copper (Cu) or tungsten, which connects the top metal layer to the redistribution layer (RDL) and under bump metallization (UBM) feature, allowing for a planar interface and reducing the need for barrier materials, thereby enabling finer line widths and spacings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If barrier materials are used in via connections to connect metal layers, then connection reliability is improved, but line width and spacing are reduced due to the additional material layers

Engineering Contradiction:

Improveconnection reliabilityVSAvoidline width

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent removes the barrier material layer from the via connection structure, extracting the problematic element that was preventing finer line widths. The via plug directly connects the first metal layer to the redistribution layer without requiring a barrier material intermediary, thus eliminating the space consumption and complexity associated with barrier layers while maintaining connection functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of adding barrier materials to prevent diffusion and ensure reliability, the patent inverts the approach by using the conductive material itself (aluminum or copper) to form the via plug that directly contacts both metal layers. This inversion eliminates the need for separate barrier layers and enables reduced line widths and spacings.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If barrier materials are used in via connections, then diffusion prevention is improved, but device complexity increases due to additional material layers and processes

Engineering Contradiction:

Improvediffusion preventionVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the barrier material layer from the via connection stack, eliminating the need for deposition and etching processes specific to barrier materials. This reduction in layers directly decreases device complexity while the via plug design maintains diffusion prevention through direct metal-to-metal contact with controlled interfaces.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the via plug formation process with the existing metal layer deposition processes, using the same aluminum or copper materials and deposition techniques. This consolidation eliminates separate barrier material processing steps and reduces overall device complexity while maintaining connection integrity.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If barrier materials are used in via connections, then material diffusion control is improved, but manufacturing precision requirements increase due to additional interface alignment needs

Engineering Contradiction:

Improvematerial diffusion controlVSAvoidinterface alignment precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

By removing the barrier material layer, the patent eliminates the additional interfaces that would require precise alignment. The via plug creates a direct connection between the first metal layer and redistribution layer, reducing the number of critical alignment interfaces from three (metal-barrier, barrier-via, via-metal) to two (metal-via, via-metal), thereby reducing manufacturing precision requirements.

Inventive Principle:

Principle #2Taking out (Extraction)

4Reliability

If conventional via connections with barrier materials are used, then connection stability is maintained, but productivity decreases due to additional deposition and etching steps

Engineering Contradiction:

Improveconnection stabilityVSAvoidmanufacturing efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent merges the via plug formation with the metal layer deposition processes, using the same aluminum or copper materials and deposition equipment. This consolidation eliminates separate barrier material deposition and etching steps, directly improving manufacturing efficiency and productivity while maintaining connection stability through the direct metal-to-metal via plug connection.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11049829B2Redistribution metal and under bump metal interconnect structures and method

Publication Date: 2021.06.29 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

An integrated circuit die includes a metal layer, a first passivation layer disposed above the metal layer, an aluminum containing redistribution layer disposed above the first passivation layer, an under bump metallization layer, and a redistribution layer plug. The redistribution layer plug is coupled to the metal layer and disposed in a via in the first passivation layer. The under bump metallization layer is coupled to the aluminum containing redistribution layer above the first passivation layer at a distance from the redistribution layer plug.