Wafer-Level MEMS Protective Coating for Particle and Moisture Sealing

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Solution Overview

Problem

During the fabrication of semiconductor devices, particularly MEMS elements, existing protective methods at the end of the assembly process are inadequate in preventing particle and humidity exposure, which can impair sensor functionality due to the miniaturization of components making it difficult to detect and screen smaller particles, and traditional lid constructions do not provide absolute protection.

Innovation Solution

A protective material, such as a silicone gel, is deposited over the sensitive areas of MEMS elements at the wafer level during the front-end production process before packaging, ensuring the sensitive areas are sealed from the external environment while maintaining sensor functionality, including mechanical and electrical functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If protective material is dispensed at the end of the assembly process, then particle protection is provided, but particles from preassembly processes can reach the MEMS element surface and humidity protection is insufficient

Engineering Contradiction:

Improveparticle protectionVSAvoidprotection timing

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The protective material is deposited at the wafer level during front-end processing, which is an early stage in the manufacturing process, before the assembly process and before particles can contaminate the MEMS element. This preliminary protection ensures that the sensitive surfaces are sealed from particles and humidity throughout subsequent processing steps, eliminating the need for later protective measures and providing continuous protection from the outset.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If MEMS elements are miniaturized, then device functionality is improved, but detection and screening of particles becomes more difficult

Engineering Contradiction:

Improvedevice functionalityVSAvoidparticle detection

Core Design Contradiction:

Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protective material, while adding a layer over the MEMS element, actually benefits the device by enabling miniaturization without increasing particle contamination risk. The thin film protection allows smaller devices to be manufactured with the same level of particle protection, converting the potential harm of miniaturization (increased contamination risk) into a benefit (smaller devices with maintained protection).

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 early deposition of protective material provides effective particle and humidity protection throughout the assembly process, ensuring the MEMS elements remain functional and protected from contamination, maintaining their operability in the final product.

Implementation Method 1

depositing, prior to a package assembly process, a protective material over the sensitive area of the at least one MEMS element such that the sensitive area of at least one MEMS element is sealed from an external environment

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentUS10858245B2Deposition of protective material at wafer level in front end for early stage particle and moisture protection

Publication Date: 2020.12.08 INFINEON TECHNOLOGIES AG

AI summary

A semiconductor device and a method of manufacturing the same are provided such that a microelectromechanical systems (MEMS) element is protected at an early manufacturing stage. A method for protecting a MEMS element includes: providing at least one MEMS element, having a sensitive area, on a substrate; and depositing, prior to a package assembly process, a protective material over the sensitive area of the at least one MEMS element such that the sensitive area of at least one MEMS element is sealed from an external environment, where the protective material permits a sensor functionality of the at least one MEMS element.