U-Bump Probe Alignment Monitoring Using Current Divider Feedback

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Solution Overview

Problem

In fine pitch assembly with 2.5D and 3D die stacking, misalignments of probes with u-bumps can go unnoticed until after packaging, leading to significant yield loss and potential damage to u-bumps, as current methods rely on manual inspection and lack in-situ monitoring.

Innovation Solution

A system using a current divider apparatus with input and output probes, a current source, and resistors to measure voltages and determine proper alignment of probes with u-bump clusters, enabling real-time monitoring of probe alignment and preventing misalignment-induced damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual inspection under microscope is used to detect misalignments, then misalignments can be discovered, but it requires time, equipment and human resources, and misalignments may still go unnoticed until after packaging

Engineering Contradiction:

Improvemisalignment detection capabilityVSAvoidinspection time and delay

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent implements preliminary monitoring of probe alignment with u-bumps during the probing process itself, rather than performing inspection after the fact. The monitoring system detects misalignments in real-time during assembly, allowing immediate correction before packaging occurs, thus eliminating the need for time-consuming post-assembly inspection

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs a feedback mechanism where the monitoring system continuously provides information about probe alignment status during the probing process. This real-time feedback enables immediate detection and correction of misalignments, preventing them from going unnoticed until after packaging

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If probes are aligned using optical alignment (PTPA), then probe-to-pad alignment can be achieved, but misalignments may still occur and go undetected until after packaging

Engineering Contradiction:

Improveprobe alignment precisionVSAvoidyield rate

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent introduces real-time feedback monitoring during the probing process to detect alignment deviations as they occur. This continuous monitoring provides immediate information about alignment quality, enabling corrective action before defective products are produced, thus improving yield rate while maintaining manufacturing precision

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces reliance solely on optical alignment methods with an electrical monitoring system that measures actual current distribution during probing. This substitution provides direct electrical feedback about alignment status, complementing or replacing optical methods with a more reliable real-time detection mechanism

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If current methods are used without in-situ monitoring, then the process is simpler, but misalignments cannot be monitored in-situ and yield loss increases

Engineering Contradiction:

Improvemonitoring system complexityVSAvoidyield rate

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent enables the probing system to self-monitor its own alignment status through electrical measurements taken during normal operation. The system uses the existing probing current to detect alignment deviations, allowing the process to monitor itself without requiring separate complex monitoring equipment, thus improving yield rate with minimal added complexity

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 allows for in-situ monitoring of probe alignment, reducing yield loss and preventing damage to u-bumps by ensuring accurate alignment during the assembly process, thereby improving the reliability of 2.5D and 3D die stacking.

Implementation Method 1

a current source configured to supply a current to the input probe placed on the first cluster

Methodology Applied

Scientific EffectElectrical current flow: Conduction (electrical)

Implementation Method 2

resistors having a same resistance and being connected to ground, and tester channels at which voltages are respectively measured

Methodology Applied

Scientific EffectOhm's law voltage drop: Ohm's Law

Data Source

PatentUS11740282B1Apparatuses and methods for monitoring health of probing u-bump cluster using current divider

Publication Date: 2023.08.29 INTEL CORP

AI summary

An apparatus includes an input probe configured to be placed on a first cluster of u-bumps disposed on a semiconductor die, output probes configured to be respectively placed on multiple clusters of u-bumps disposed on the semiconductor die, the multiple clusters being separately connected to the first cluster. The apparatus further includes a space transformer and printed circuit board (PCB) portion including a current source configured to supply a current to the input probe placed on the first cluster, resistors having a same resistance and being connected to ground, and tester channels at which voltages are respectively measured, the tester channels being respectively connected to ends of the output probes respectively placed on the multiple clusters and being respectively connected to the resistors. The apparatus further includes a processor configured to determine whether the input probe is properly aligned with the first cluster, based on the measured voltages.