Planar Passivation Structure for Thinner IC Polymer Layers

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Solution Overview

Problem

In the formation of integrated circuits, achieving a planar top surface for polymer layers over non-planar dielectric layers and metal pads is challenging, leading to increased polymer thickness and overall device die thickness.

Innovation Solution

A method involving the formation of a planarization layer with a planar top surface over the metal pad, followed by the deposition of a polymer layer, which extends into openings in the planarization layer to contact the metal pad, thereby achieving a planar top surface without the need for excessive polymer thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a polymer layer is formed over non-planar dielectric layers and metal pads, then the metal pad is protected and electrically connected, but the top surface of the polymer layer becomes non-planar, requiring increased polymer thickness which increases overall device die thickness

Engineering Contradiction:

Improveplanarity of polymer layer top surfaceVSAvoiddevice die thickness

Core Design Contradiction:

Manufacturing precisionVSLength of stationary object

Solution Approach 1:

A planarization layer is formed over the non-planar dielectric layers and metal pads before forming the polymer layer. This preliminary planarization action creates a planar top surface that enables the subsequent polymer layer to be formed with reduced thickness while maintaining planarity, thus resolving the contradiction between surface planarity and device thickness

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The planarization layer acts as an intermediary structure between the non-planar underlying layers (dielectric layers and metal pads) and the polymer layer. It mediates the transition from non-planar to planar surface, allowing the polymer layer to achieve the required planarity without increasing overall device thickness

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 allows for a more planar top surface of the polymer layer, reducing the overall thickness of the device dies and improving wafer-to-wafer bonding efficiency.

Implementation Method 1

A planarization layer is deposited over the metal pad. The planarization layer includes a bottom surface over the metal pad and a planar top surface

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentUS12218022B2Passivation structure with planar top surfaces

Publication Date: 2025.02.04 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method includes forming a first passivation layer, forming a metal pad over the first passivation layer, forming a planarization layer having a planar top surface over the metal pad, and patterning the planarization layer to form a first opening. A top surface of the metal pad is revealed through the first opening. The method further includes forming a polymer layer extending into the first opening, and patterning the polymer layer to form a second opening. The top surface of the metal pad is revealed through the second opening.