Redistribution Layer Planarization for Flat Passivation Surfaces

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Solution Overview

Problem

The complexity of semiconductor manufacturing is increased by non-planar topographical features in redistribution layers (RDL) and passivation layers, leading to voids and non-uniformity, which affect the bonding capacity and process efficiency.

Innovation Solution

A method involving the use of an etch stop layer, sacrificial layer, and chemical mechanical polishing (CMP) to create a flat passivation surface, along with the insertion of dummy pattern objects to adjust pattern density and balance warpage, ensuring a flat RDL structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If non-planar topographical features are formed in RDL and passivation layers, then routing flexibility is improved, but manufacturing complexity increases and voids are generated

Engineering Contradiction:

Improverouting flexibilityVSAvoidmanufacturing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

A planarization layer is deposited in advance to fill the non-planar topographical features before subsequent bonding and processing steps. This preliminary planarization prevents manufacturing complexity and void formation in later stages while preserving the routing flexibility provided by the underlying non-planar RDL structure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The planarization layer acts as an intermediary between the non-planar RDL/passivation structure and the subsequent bonding processes. It mediates the conflict by providing a flat surface for manufacturing while allowing the underlying complex structure to maintain its routing functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If non-planar topographical features are formed in RDL and passivation layers, then routing flexibility is improved, but bonding capacity deteriorates

Engineering Contradiction:

Improverouting flexibilityVSAvoidbonding capacity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The planarization layer is deposited beforehand to create a flat surface, ensuring that subsequent bonding operations occur on a uniform plane. This preliminary action eliminates the negative impact of non-planar features on bonding capacity while preserving the routing flexibility of the underlying structure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The planarization layer serves as an intermediary that decouples the routing flexibility requirement from the bonding capacity requirement. It allows the underlying structure to be non-planar for routing purposes while presenting a planar surface for bonding operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Area of stationary object

If additional passivation layers are deposited to cover non-planar features, then surface coverage is improved, but voids and non-uniformity increase

Engineering Contradiction:

Improvesurface coverageVSAvoidsurface uniformity

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The planarization layer is deposited in advance to fill and flatten the non-planar topographical features before additional passivation layers are applied. This preliminary planarization ensures that subsequent layers can be deposited uniformly without creating voids or non-uniformity, while still achieving complete surface coverage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The planarization layer acts as an intermediary between the non-planar underlying structure and the additional passivation layers. It mediates the conflict by providing a uniform deposition surface that eliminates void formation while maintaining complete coverage of the underlying features.

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

The method achieves a flat RDL surface with reduced voids and improved process uniformity, enhancing bonding capacity and reducing fabrication costs by optimizing pattern loading and surface flatness.

Implementation Method 1

chemical mechanical polishing (CMP) to create a flat passivation surface

Methodology Applied

Scientific EffectChemical mechanical polishing:

Data Source

PatentUS12543545B2Redistribution layer and methods of fabrication thereof

Publication Date: 2026.02.03 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Embodiments of the present disclosure provide methods of forming a RDL structure with a flat passivation surface. Some embodiments provide a stop layer for chemical mechanical polishing disposed under a passivation layer. Some embodiments provide an extra thickness of passivation deposition and a sacrificial passivation layer for passivation polishing. Some embodiments provide a modified RDL pattern by inserting dummy pattern objects to adjust pattern density.