Electrically Active IC Fiducials Without Keep-Out Zones

Solution Overview

Problem

In IC packaging, the use of a metal-free keep out zone (KOZ) for fiducial alignment interferes with the alignment accuracy due to metal reflection, reducing the active area and conductive pad density, leading to decreased electrical capacity and signal transmission efficiency.

Innovation Solution

The implementation of electrically active interconnect pads forming the fiducial pattern, allowing for pre-bond alignment without IR imaging, which eliminates the need for a KOZ and enables increased pad density and transistor functionality in previously inaccessible areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a metal-free keep out zone (KOZ) is used for fiducial alignment, then alignment accuracy is improved by preventing metal reflection interference, but the active area and conductive pad density are reduced

Engineering Contradiction:

Improvealignment accuracyVSAvoidactive area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent replaces the optical imaging system (IR light-based fiducial detection) with an electrical measurement system. Instead of using optical fiducials that require metal-free KOZ regions for accurate imaging, the invention uses electrical measurements taken at the bonding interface to detect and correct misalignment. This substitution eliminates the need for KOZ regions, allowing full utilization of the die area for conductive pads and active circuitry while maintaining alignment accuracy through electrical feedback mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a metal-free keep out zone (KOZ) is used for fiducial alignment, then alignment accuracy is improved by preventing metal reflection interference, but the conductive pad density is reduced

Engineering Contradiction:

Improvealignment accuracyVSAvoidconductive pad density

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent replaces the optical imaging system (IR light-based fiducial detection) with an electrical measurement system. Instead of using optical fiducials that require metal-free KOZ regions for accurate imaging, the invention uses electrical measurements taken at the bonding interface to detect and correct misalignment. This substitution eliminates the need for KOZ regions, allowing full utilization of the die area for conductive pads and active circuitry while maintaining alignment accuracy through electrical feedback mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If a metal-free keep out zone (KOZ) is used for fiducial alignment, then alignment accuracy is improved by preventing metal reflection interference, but the electrical capacity and signal transmission bandwidth are reduced

Engineering Contradiction:

Improvealignment accuracyVSAvoidelectrical capacity

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces the optical imaging system (IR light-based fiducial detection) with an electrical measurement system. Instead of using optical fiducials that require metal-free KOZ regions for accurate imaging, the invention uses electrical measurements taken at the bonding interface to detect and correct misalignment. This substitution eliminates the need for KOZ regions, allowing full utilization of the die area for conductive pads and active circuitry while maintaining alignment accuracy through electrical feedback mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20240063136A1Integrated circuit device with electrically active fiducials

Publication Date: 2024.02.22 INTEL CORP

AI summary

An integrated circuit (IC) device comprises an array comprising rows and columns of conductive interconnect pads. At least one optical alignment fiducial region is distinct from the array and comprises a fiducial pattern, wherein the fiducial pattern comprises a first group of pads contiguous to a second group of pads, and wherein a width of a space between nearest pads of the first and second groups is wider than the spaces between pads within each group.