Package Opening Formation With Scalloped Sidewalls for PoP Contacts

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Solution Overview

Problem

The semiconductor industry faces challenges in forming openings for connectors in package structures, particularly in achieving a critical size and smooth edge profile, which affects the integration density and reliability of package-on-package (PoP) devices due to the limitations of existing manufacturing processes like laser drilling, leading to distorted and non-smooth edges.

Innovation Solution

A manufacturing method involving a combination of laser drilling and etching processes to form openings in the dielectric layer, where laser drilling creates an initial opening with a bowl shape and subsequent etching expands the opening outward, increasing the included angle beyond 60 degrees, resulting in a scallop sidewall and improved critical dimension, and smooth edge profile.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If laser drilling is used to form openings in the dielectric layer, then the opening can be created efficiently, but the edge profile becomes distorted and non-smooth

Engineering Contradiction:

Improveopening formation efficiencyVSAvoidedge profile smoothness

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The opening formation process is divided into two distinct stages: first, laser drilling creates the initial opening efficiently; second, chemical etching refines the opening edges to achieve smooth profiles. This segmentation allows each process to optimize for its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A mandrel structure is introduced as an intermediary element during the etching process. The mandrel serves as a template that defines the final opening geometry and protects surrounding areas, enabling precise control over the opening shape and smooth edge formation while maintaining process efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Area of moving object

If the opening size is reduced to achieve critical dimension, then integration density improves, but the edge smoothness and reliability deteriorate

Engineering Contradiction:

Improveopening critical dimensionVSAvoidedge smoothness

Core Design Contradiction:

Area of moving objectVSManufacturing precision

Solution Approach 1:

The mechanical laser drilling process is supplemented with a chemical etching process. The chemical etching uses isotropic etching characteristics to smoothly round the sharp edges created by laser drilling, achieving superior edge smoothness at critical dimensions that mechanical processes alone cannot provide.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The etching process parameters (etchant composition, temperature, time) are carefully controlled and optimized to achieve the desired opening dimension and edge smoothness. By adjusting these parameters, the process can produce smooth edges even at reduced critical dimensions, maintaining reliability while improving integration density.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If laser drilling creates an opening, then the process is simple and fast, but the included angle remains small and edge quality is poor

Engineering Contradiction:

Improveprocess simplicityVSAvoidopening geometry

Core Design Contradiction:

Device complexityVSShape

Solution Approach 1:

The laser drilling step performs preliminary action by creating the initial opening structure quickly and simply. This preliminary opening serves as the foundation for the subsequent etching process, which then refines the geometry to achieve the desired included angle and edge quality without requiring complete restructuring.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The process combines two different mechanisms (laser ablation and chemical etching) to create a composite effect. The laser provides rapid material removal while the chemical etchant provides precise geometric control and surface smoothing, together achieving results that neither process could accomplish alone.

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 method enhances the critical dimension and smoothness of the opening, ensuring better exposure and contact of conductive structures, leading to favorable and reliable electrical connections between package structures, thereby improving the reliability and efficiency of PoP devices without significantly altering manufacturing steps or increasing costs.

Implementation Method 1

an opening is formed in the dielectric layer by a laser drilling process

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

an etching process is performed on the opening

Methodology Applied

Scientific EffectChemical etching:

Data Source

PatentUS11929322B2Method of forming device and package structure

Publication Date: 2024.03.12 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Device, package structure and method of forming the same are disclosed. The device includes a die encapsulated by an encapsulant, a conductive structure aside the die, and a dielectric layer overlying the conductive structure. The conductive structure includes a through via in the encapsulant, a redistribution line layer overlying the through via, and a seed layer overlying the redistribution line layer. The dielectric layer includes an opening, wherein the opening exposes a surface of the conductive structure, the opening has a scallop sidewall, and an included angle between a bottom surface of the dielectric layer and a sidewall of the opening is larger than about 60 degrees.