Moisture-Impenetrable Guard Ring for IC Sensor Integration

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Solution Overview

Problem

Integrated circuits (ICs) with multiple sensors face challenges in preventing moisture penetration through the metallization stack, which can interfere with the correct operation of underlying circuit elements, especially when forming cavities for sensors like shock sensors that require environmental exposure.

Innovation Solution

A method involving the deposition of a moisture-impenetrable layer over the metallization stack, followed by a passivation layer patterning to create a trench, filling this trench with a further moisture-impenetrable material, and exposing the passivation layer to form a guard ring that protects the IC from moisture, using aluminum (Al) which is readily available in IC manufacturing processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a moisture barrier layer is deposited over the metallization stack to protect underlying circuitry, then protection against moisture penetration is improved, but the ability to integrate sensors requiring environmental exposure deteriorates

Engineering Contradiction:

Improveprotection against moisture penetrationVSAvoidability to integrate sensors requiring environmental exposure

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The moisture barrier layer is segmented into different regions: a first moisture barrier layer covering the metallization stack, and a second moisture barrier layer covering the first sensing element. This segmentation allows the first sensing element to be exposed to the environment while the metallization stack remains protected, resolving the contradiction between moisture protection and sensor integration capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the IC structure are assigned different moisture barrier properties. The metallization stack region receives a moisture-impenetrable first moisture barrier layer, while the sensing element region receives a moisture-impenetrable second moisture barrier layer that allows environmental interaction. This local differentiation enables simultaneous moisture protection and sensor functionality.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the moisture barrier layer is partially removed to expose sensing elements, then sensor functionality is improved, but moisture penetration risk increases

Engineering Contradiction:

Improvesensor functionalityVSAvoidmoisture penetration risk

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The second moisture barrier layer is deposited over the first sensing element before any environmental exposure is created. This preliminary application of the moisture barrier ensures that even when the sensing element is exposed to the environment for sensor functionality, the moisture barrier is already in place to prevent moisture penetration, thus maintaining reliability while enabling sensor operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The moisture barrier system uses a composite structure with a first moisture barrier layer (e.g., Ta2O5) over the metallization stack and a second moisture barrier layer over the sensing element. This composite moisture barrier approach provides enhanced moisture protection while allowing the sensing element to interact with the environment, resolving the contradiction between sensor functionality and moisture protection.

Inventive Principle:

Principle #40Composite materials

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 effectively reduces the risk of moisture penetration into the IC, protecting the internal circuitry by forming a robust moisture barrier even when the moisture-impenetrable layer is disrupted for sensor integration, thereby ensuring the IC's operational integrity.

Implementation Method 1

depositing a moisture-impenetrable layer over the metallization stack

Methodology Applied

Scientific EffectMoisture barrier:

Implementation Method 2

patterning the passivation layer and underlying moisture-impenetrable layer such that a trench is formed surrounding a region of the passivation layer

Methodology Applied

Scientific EffectPatterning:

Implementation Method 3

depositing a layer of a further moisture-impenetrable material over the resultant structure thereby filling said trench

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentUS8866239B2IC manufacturing method, IC and apparatus

Publication Date: 2014.10.21 SCIOSENSE BV

AI summary

A method of manufacturing an integrated circuit having a substrate comprising a plurality of components and a metallization stack over the components, the metallization stack comprising a first sensing element and a second sensing element adjacent to the first sensing element.