Liquid Blasting for Embedded Die Contact Formation

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Solution Overview

Problem

Conventional methods for forming contact openings in semiconductor packages, such as laser drilling and plasma etching, are limited by small opening sizes, high processing time, and incompatibility with certain encapsulation materials, making them inefficient for large-area contact formation and high-current semiconductor dies.

Innovation Solution

A liquid blasting process is used to form large-area contact openings in semiconductor packages, where a pressurized stream of liquid is directed through a metal mask to remove encapsulation material and expose terminals, allowing for the formation of electrically conductive vias, which can be enhanced with additives like silicon oxide and nitride, and can be applied to both sides of the encapsulation material for improved thermal performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If laser drilling is used to form contact openings, then contact openings can be formed in encapsulation material, but the size of contact openings is restricted to diameters less than 140 μm and processing time is lengthy

Engineering Contradiction:

Improvecontact opening areaVSAvoidprocessing time

Core Design Contradiction:

Area of moving objectVSLoss of time

Solution Approach 1:

The patent replaces the laser drilling process with a mechanical drilling process. A drill bit is used to mechanically remove encapsulation material and form contact openings, eliminating the size restrictions and lengthy processing times associated with laser drilling. The mechanical drilling allows for larger diameter contact openings and faster processing speeds.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameter of contact opening formation from thermal (laser) to mechanical (drilling). This parameter change enables larger contact opening diameters and significantly reduces processing time, as mechanical drilling can remove material much faster than laser ablation and is not constrained by the same physical limitations.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If plasma etching is used to remove encapsulation material, then organic material can be removed, but it is not compatible with glass-reinforced epoxy laminate materials

Engineering Contradiction:

Improvecompatibility with encapsulation materialsVSAvoidmaterial removal effectiveness

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces the chemical plasma etching process with a mechanical drilling process. The mechanical drill bit physically removes encapsulation material through abrasion and fracture, making it compatible with glass-reinforced epoxy laminate materials that are resistant to plasma etching. This mechanical approach provides universal applicability across different encapsulation material types.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Area of moving object

If multiple micro-vias are drilled for each die terminal to achieve sufficient contact area, then contact area can be increased, but the number of micro-vias required is very high (hundreds per terminal) and processing complexity increases

Engineering Contradiction:

Improvetotal contact areaVSAvoidnumber of contact openings

Core Design Contradiction:

Area of moving objectVSDevice complexity

Solution Approach 1:

The patent uses mechanical drilling with appropriately sized drill bits to create single, large-diameter contact openings that provide sufficient contact area without requiring hundreds of micro-vias. The mechanical process allows for direct formation of large openings in one step, simplifying the overall structure and reducing processing complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The liquid blasting process significantly reduces processing time and cost while enabling larger contact openings, maximizing terminal exposure and thermal performance, and is compatible with various encapsulation materials, including FR4 glass-reinforced epoxy laminate.

Implementation Method 1

directing a pressurized stream of liquid toward the first surface of the encapsulation material with the first metal mask, to remove the first exposed part of the encapsulation material

Methodology Applied

Scientific EffectErosion: Erosion

Data Source

PatentUS11043409B2Method of forming contacts to an embedded semiconductor die and related semiconductor packages

Publication Date: 2021.06.22 INFINEON TECHNOLOGIES AG

AI summary

A method of forming contacts to an embedded semiconductor die includes embedding a semiconductor die in an encapsulation material, the semiconductor die having a first terminal at a first side of the semiconductor die, forming a first metal mask on a first surface of the encapsulation material, the first metal mask being positioned over the first side of the semiconductor die and exposing a first part of the encapsulation material aligned with the first terminal of the semiconductor die, directing a pressurized stream of liquid toward the first surface of the encapsulation material with the first metal mask, to remove the first exposed part of the encapsulation material and form a first contact opening to the first terminal of the semiconductor die, and forming an electrically conductive material in the first contact opening. Related semiconductor packages are also described.