Semiconductor Packaging Cavity Conformal Layer Protection

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Solution Overview

Problem

Existing overmolding techniques for semiconductor packaging, which involve creating cavities in the mold material using sacrificial 3D structures, often result in interior surfaces that are not resistant to fluid substances, posing challenges in applications like biosensing where exposure to liquids is necessary.

Innovation Solution

A method where 3D structures of sacrificial material are produced and embedded in a mold substrate, followed by the application of a conformal layer that remains intact after the sacrificial material is removed, creating cavities with a protective layer on the interior surfaces, which can act as a moisture barrier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If sacrificial 3D structures are removed to create cavities in the mold material, then the cavities are formed for fluid contact, but the interior surfaces of the cavities are not resistant to fluid substances

Engineering Contradiction:

Improvefluid contact capabilityVSAvoidinterior surface resistance to fluids

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A conformal layer is deposited on the sacrificial 3D structures before overmolding, and this layer is preserved after sacrificial material removal to line the interior surfaces of the resulting cavities. This preliminary protective coating prevents fluid damage to the mold material interior surfaces while maintaining cavity functionality for fluid contact applications.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The conformal layer acts as an intermediary barrier between the fluid substances and the mold material interior surfaces. This intermediate layer provides chemical resistance and protection, allowing the cavities to come into contact with aggressive fluids without degrading the structural integrity of the mold substrate.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a conformal layer is applied on 3D structures before overmolding, then the interior surfaces gain fluid resistance, but the process complexity increases

Engineering Contradiction:

Improveinterior surface resistance to fluidsVSAvoidpackaging process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The conformal layer deposition step is integrated into the existing overmolding process sequence, combining the protective coating application with the cavity formation process. This merging of operations adds the necessary fluid resistance functionality without requiring completely separate process equipment or procedures.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The conformal layer is designed with specific material properties and thickness parameters that optimize both protection and process integration. By carefully controlling the layer's physical and chemical parameters, the solution achieves fluid resistance while maintaining compatibility with standard semiconductor packaging process parameters.

Inventive Principle:

Principle #35Parameter changes

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 ensures that the interior surfaces of the cavities in the mold substrate are protected from fluid substances, enhancing the reliability and functionality of semiconductor packages, especially those used in biosensing applications.

Implementation Method 1

forming a conformal layer at least on the one or more 3-dimensional structures

Methodology Applied

Scientific EffectConformal deposition: Deposition (physical)

Implementation Method 2

thinning at least part of the first mold substrate, thereby removing the conformal layer from an upper surface of the one or more 3-dimensional sacrificial structures, thereby exposing the 3-dimensional sacrificial structures

Methodology Applied

Scientific EffectMaterial removal: Ablation

Data Source

PatentUS11462420B2Method for packaging semiconductor dies

Publication Date: 2022.10.04 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)

AI summary

A method for packaging semiconductor dies by overmolding is disclosed. The dies are embedded in a substrate of a mold material, and cavities are produced in the mold substrate by producing 3D structures of a sacrificial material prior to the overmolding step. Afterwards, the sacrificial material is removed to thereby create cavities in the mold substrate. A conformal layer is produced on the 3D structures prior to overmolding, and the mold substrate is thinned to expose an upper surface of the 3D structures. The conformal layer is not removed when the sacrificial structures are removed. In this way, the conformal layer remains on the surfaces of the mold substrate inside the cavity. In one aspect, the conformal layer may have a protective function, useful in the production of packages including dies which come into contact with fluid substances.