Semiconductor Passivation Layer Structure for Flip Chip Adhesion

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Solution Overview

Problem

Standard solder bump manufacture processes in flip chip packaging face issues such as peeling of the polyimide layer and contamination, leading to increased failure rates due to moisture penetration and delamination of low-k dielectric layers, which affect the robustness and reliability of semiconductor assemblies.

Innovation Solution

A semiconductor component structure is developed with a second passivation layer having specific openings that expose the bond pad and underlying passivation layer, combined with a buffer layer and under bump metallurgy, to absorb stress and enhance adhesion, thereby reducing the risk of peeling and contamination during assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If standard solder bump manufacture processes are used, then the packaging process is simple, but the polyimide layer peels and moisture penetrates through the die

Engineering Contradiction:

Improvepackaging process simplicityVSAvoidassembly failure rate

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent divides the passivation structure into multiple layers: a first passivation layer (polyimide) and a second passivation layer (spin-on-glass or benzocyclobutene). This segmentation allows each layer to perform specific functions - the polyimide provides stress management while the second layer provides moisture barrier protection, preventing both peeling and moisture penetration issues that occur with single-layer structures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses composite material structures by combining different passivation materials (polyimide with spin-on-glass or benzocyclobutene) to achieve properties that neither material alone can provide. The composite structure delivers both the stress absorption capability of polyimide and the moisture barrier properties of the second layer, resolving the reliability issues while maintaining manufacturing feasibility.

Inventive Principle:

Principle #40Composite materials

2Strength

If a second passivation layer is added to prevent peeling, then adhesion improves, but the structure complexity increases

Engineering Contradiction:

ImproveadhesionVSAvoidpassivation structure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The passivation function is segmented into two distinct layers with specific roles: the first polyimide layer handles stress management and the second layer (spin-on-glass or benzocyclobutene) provides enhanced adhesion and moisture protection. This segmentation improves adhesion strength while keeping each layer's function simple and well-defined.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent modifies the passivation structure by adding a second layer with different material properties (spin-on-glass or benzocyclobutene) that have superior adhesion characteristics. This parameter change in the passivation system enhances overall adhesion strength without requiring complex structural modifications, as the second layer is simply deposited over the first layer.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If openings are created in the second passivation layer, then electrical connection is enabled, but contamination risk increases

Engineering Contradiction:

Improveelectrical connection capabilityVSAvoidcontamination

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The second passivation layer is deposited over the entire surface before any opening formation, creating a preliminary protective barrier. When openings are subsequently created for electrical connections, the surrounding areas remain protected by the second layer, preventing contamination from reaching exposed surfaces during assembly operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The second passivation layer acts as a flexible protective film that can be selectively opened while maintaining coverage over most surfaces. This thin film structure enables electrical connections through controlled openings while the remaining continuous film provides ongoing protection against contamination, balancing connectivity needs with contamination prevention.

Inventive Principle:

Principle #30Flexible shells and thin films

Data Source

PatentUS10074584B2Method of forming a semiconductor component comprising a second passivation layer having a first opening exposing a bond pad and a plurality of second openings exposing a top surface of an underlying first passivation layer

Publication Date: 2018.09.11 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A conductive feature on a semiconductor component is disclosed. A first passivation layer is formed over a substrate. A bond pad is formed over the first passivation layer. A second passivation layer overlies the first passivation layer and the bond pad. The second passivation layer has a first opening overlying the bond pad and a plurality of second openings exposing a top surface of the first passivation layer. A buffer layer overlies the second passivation layer and fills the plurality of second openings. The buffer layer has a third opening overlapping the first opening and together exposes a portion the bond pad. The combined first opening and third opening has sidewalls. An under bump metallurgy (UBM) layer overlies the sidewalls of the combined first opening and third opening, and contacts the exposed portion of the bond pad. A conductive feature overlies the UBM layer.