Wafer Protective Cap Fabrication via Cavity Molding

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Solution Overview

Problem

The conventional method of fabricating protective caps for wafer level chip scale packages involves complex and time-consuming processes, including multiple dicing operations that increase the risk of misalignment and damage to fragile micro-electromechanical structures due to pollution from micro-particles, reducing the yield of the packaging process.

Innovation Solution

A method involving a non-metal cap substrate with a formed metal layer and cavities corresponding to devices on the wafer surface, where protective caps are created using the cavities as molds, eliminating the need for additional dicing by aligning and connecting the caps directly to the devices and removing the metal layer, thereby reducing damage and increasing yield.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If multiple dicing operations are performed to fabricate protective caps and expose bonding pads, then the protective caps can be formed and bonding pads exposed, but the risk of misalignment and damage to fragile structures increases due to micro-particle pollution

Engineering Contradiction:

Improvealignment precisionVSAvoiddamage risk to fragile structures

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent combines the protective cap formation and bonding pad exposure into a single dicing operation by designing the dicing pattern to simultaneously achieve both objectives. The dicing lines are strategically positioned to separate protective caps from the substrate while exposing bonding pads, eliminating the need for sequential dicing operations and reducing misalignment risks.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent performs preliminary actions by pre-forming protective caps over fragile structures before the final dicing operation. The cap substrate is prepared with protective caps in advance, and the bonding pads are designed to be exposed during the same dicing step that separates the protective caps, preventing damage by avoiding repeated handling and dicing of fragile structures.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If multiple dicing operations are performed to fabricate protective caps, then the protective caps can be formed, but the processing time and complexity increase

Engineering Contradiction:

Improveprotective cap formationVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent merges multiple dicing operations into a single operation by designing the dicing pattern to simultaneously separate protective caps and expose bonding pads. This consolidation reduces processing time and simplifies the manufacturing process while maintaining the integrity of protective caps.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single dicing operation serves multiple functions: it separates the protective caps from the substrate, exposes the bonding pads for electrical connections, and defines the final package structure. This multi-functional approach eliminates the need for separate dicing steps and reduces overall processing time.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If protective caps are formed using conventional methods, then the fragile structures are protected, but the bonding pads are covered requiring additional dicing to expose them

Engineering Contradiction:

Improveprotection of fragile structuresVSAvoidnumber of dicing operations

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the protective cap formation and bonding pad exposure into a single integrated process. The dicing pattern is designed to simultaneously achieve both objectives, eliminating the need for additional dicing operations to expose bonding pads after protective caps are formed.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent performs preliminary actions by pre-configuring the cap substrate with protective caps that are positioned and sized to protect fragile structures while allowing bonding pads to be exposed in the same dicing operation. The bonding pads are designed to be accessible after a single dicing step.

Inventive Principle:

Principle #10Preliminary action

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 significantly reduces damage to the wafer and devices from the dicing process, enhances the packaging process yield, and allows for mass production of protective caps without the extra dicing step, ensuring effective protection of fragile structures without compromising electrical connections.

Implementation Method 1

forming a metal layer on the non-metal cap substrate

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentUS7410886B2Method for fabricating protective caps for protecting elements on a wafer surface

Publication Date: 2008.08.12 ADVANCED SEMICON ENG INC

AI summary

A method of fabricating protective caps for protecting devices on wafer surface includes: (a) providing a non-metal cap substrate and forming a metal layer on the non-metal cap substrate; (b) forming a plurality of cavities on a surface of the metal layer, wherein the location of each cavity corresponds to each of the devices on the wafer surface; and (c) forming a protective cap in each cavity and forming a plurality of bonding media around the cavities.