High-Voltage Bonding Pad Nitride Contact Without Extra BEOL Mask

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Solution Overview

Problem

Existing integrated circuit fabrication processes require specialized Nickel-Palladium finishing or a dedicated processing mask to connect a passivation nitride layer with a high voltage metal bonding pad, adding extra cost and complexity.

Innovation Solution

A self-aligned BEOL process using a conformal nitride layer and a photosensitive insulator layer to form a connection with the high voltage bonding pad without needing Nickel-Palladium finishing or a dedicated mask, by utilizing the photosensitive insulator layer as a mask to etch the nitride layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Nickel-Palladium finishing is used to connect passivation nitride layer with high voltage metal bonding pad, then reliability is improved, but manufacturing cost and process complexity increase

Engineering Contradiction:

Improveconnection reliabilityVSAvoidprocess complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the specialized Nickel-Palladium finishing process from the fabrication sequence by using a standard photosensitive insulator layer as mask instead, thereby removing the complexity and cost associated with specialized finishing processes while maintaining the essential function of creating a reliable connection between the passivation nitride layer and metal bonding pad

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The photosensitive insulator layer is given multiple functions: it serves as both the standard lithographic mask for defining bonding pad geometry and as the etch mask for creating openings in the passivation nitride layer. This multi-functionality eliminates the need for dedicated specialized masks or finishing processes, reducing overall process complexity while maintaining connection reliability

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of manufacture

If a dedicated processing mask is used to connect passivation nitride layer with metal bonding pad, then connection is achieved, but manufacturing cost increases

Engineering Contradiction:

Improveconnection formationVSAvoidprocess steps

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges the function of the standard photosensitive insulator layer with the etch mask function by using the same layer to define both the bonding pad geometry and the opening in the passivation nitride layer. This consolidation eliminates the need for separate dedicated masks, reducing the number of process steps and associated costs while maintaining precise alignment through self-alignment

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If specialized Nickel-Palladium finishing is implemented, then connection reliability is improved, but fabrication cost increases

Engineering Contradiction:

Improvebonding pad connectionVSAvoidfabrication cost

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses standard, readily available photosensitive insulator materials and conventional lithographic/etching processes instead of expensive specialized Nickel-Palladium finishing. The standard photosensitive insulator layer, which is already part of the conventional BEOL stack, serves as the etch mask, eliminating the need for costly specialized materials and processes while achieving the same connection reliability

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 method reduces fabrication costs and complexity by eliminating the need for specialized finishing or additional masks, while maintaining reliability through self-alignment of the nitride layer with the bonding pad.

Implementation Method 1

a conformal nitride layer extending over the passivation structure and in contact with the upper surface of the last metal structure

Methodology Applied

Scientific EffectConformal deposition: Deposition (physical)

Implementation Method 2

an insulator material layer covering the conformal nitride layer and including a second opening extending through both the insulator material layer and the conformal nitride layer

Methodology Applied

Scientific EffectPhotoresist masking:

Implementation Method 3

using the insulator material layer with the second opening as a mask to etch through the nitride layer

Methodology Applied

Scientific EffectEtching:

Data Source

PatentUS12463163B2Integrated circuit chip including a passivation nitride layer in contact with a high voltage bonding pad and method of making

Publication Date: 2025.11.04 STMICROELECTRONICS SRL

AI summary

A back end of line (BEOL) structure for an integrated circuit chip includes a last metal structure providing a bonding pad. A passivation structure over the bonding pad includes a first opening extending exposing an upper surface of the bonding pad. A conformal nitride layer extends over the passivation structure and is placed in contact with the upper surface of the bonding pad. An insulator material layer covers the conformal nitride layer and includes a second opening that extends through both the insulator material layer and the conformal nitride layer. A foot portion of the conformal nitride layer on the upper surface of the bonding pad is self-aligned with the second opening.