Interposer Ground Pad Dissipates Electrostatic Charge for Stacked Die

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Solution Overview

Problem

The formation of stacked die integrated circuits is prone to damage due to electrostatic charge discharge from the interposer, which can reduce yield and reliability, as passive interposers lack conventional ESD protection and are exposed to ionic charges during processing.

Innovation Solution

Incorporating ground pads on the interposer that are grounded using a probe to dissipate electrostatic charge before attaching integrated circuit dies, providing a reference ground and mitigating the risk of damage during die attach.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple die are stacked to form a stacked die IC, then power consumption is reduced, current leakage is reduced, performance is improved, and IC size is reduced, but the risk of damage to integrated circuit dies increases due to electrostatic charge discharge from the interposer

Engineering Contradiction:

Improvestacked die reliabilityVSAvoidelectrostatic charge discharge damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The interposer is grounded before the integrated circuit die is attached to it. The grounding probe makes contact with the ground pad on the interposer, dissipating any accumulated electrostatic charge prior to die attach, thereby preventing ESD damage to the die

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A grounding probe serves as an intermediary tool that temporarily connects the interposer to ground potential, providing a controlled path for charge dissipation without directly connecting the die to ground during the attach process

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a grounded probe is used to dissipate electrostatic charge from the interposer, then the risk of damage to integrated circuit dies is reduced, but the complexity of the die attach process increases

Engineering Contradiction:

Improvedie attach reliabilityVSAvoiddie attach process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The interposer itself provides the grounding capability through its integrated ground pad, eliminating the need for external grounding equipment or complex grounding arrangements. The ground pad is already part of the interposer structure, ready to accept charge dissipation

Inventive Principle:

Principle #25Self-service

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 solution effectively reduces the risk of damage to integrated circuit dies by grounding the interposer, thereby increasing the yield and reliability of stacked die formation by preventing electrostatic discharge and ensuring the interposer does not act as a source of charge during die attach.

Implementation Method 1

The interposer includes a pad coupled to a conductive network of the interposer to dissipate electrostatic charge from the interposer

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The grounded probe is put in mechanical contact with a pad on the interposer for the grounding thereof to dissipate electrostatic charge from the interposer

Methodology Applied

Scientific EffectElectrostatic discharge: Electrostatic Discharge

Data Source

PatentUS10015916B1Removal of electrostatic charges from an interposer via a ground pad thereof for die attach for formation of a stacked die

Publication Date: 2018.07.03 XILINX INC

AI summary

An apparatus relating generally to an interposer is disclosed. In such an apparatus, the interposer has a plurality of conductors for coupling an integrated circuit die to the interposer to provide a stacked die. The interposer includes a pad coupled to a conductive network of the interposer to dissipate electrostatic charge from the interposer.