Die Stacking Yield via Partial Package System Testing

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Solution Overview

Problem

Conventional die testing and assembly flows result in high waste rates due to system tests being performed after dies are packaged, leading to the discard of both the package and dies if the test fails, thereby reducing overall yield.

Innovation Solution

A method that involves performing a wafer test on individual dies, forming a partial package if successful, and then conducting system tests on the partial package before stacking additional dies, allowing for the identification of non-functional dies early in the process and preventing unnecessary waste.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If system test is performed after dies are packaged, then packaging efficiency is improved, but yield is reduced due to discard of both package and dies if test fails

Engineering Contradiction:

Improvepackaging efficiencyVSAvoidyield

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent performs system tests on individual dies before they are packaged, rather than after packaging. This preliminary testing action identifies non-functional dies early, allowing only functional dies to proceed to packaging and stacking, thereby preventing waste of packaging materials and improving yield while maintaining packaging efficiency

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If system test is performed after dies are packaged, then process simplicity is improved, but waste increases as both package and dies are discarded if test fails

Engineering Contradiction:

Improveprocess simplicityVSAvoidwaste

Core Design Contradiction:

Device complexityVSLoss of substance

Solution Approach 1:

The patent segments the testing process into two distinct stages: individual die system testing before packaging, and package-level functional testing after stacking. This segmentation allows early identification and removal of defective dies, preventing waste of packaging materials and subsequent dies, while maintaining clear process steps

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs system tests on individual dies before packaging, which is a preliminary action that identifies non-functional dies early in the process. This prevents unnecessary packaging and stacking of defective dies, reducing material waste while keeping the overall process relatively simple

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If wafer test is performed on individual dies, then identification of non-functional dies is improved, but process complexity increases

Engineering Contradiction:

Improveidentification accuracyVSAvoidprocess complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent performs wafer-level system tests on individual dies before packaging as a preliminary action. This early testing provides precise identification of non-functional dies, and by integrating this into the existing wafer fabrication process, the additional complexity is minimized while achieving accurate defect detection

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8451014B2Die stacking, testing and packaging for yield

Publication Date: 2013.05.28 ADVANCED MICRO DEVICES INC

AI summary

A method to test and package dies so as to increase overall yield is provided. The method includes performing a wafer test on a first die and mounting the first die on a package substrate to form a partial package, if the wafer test of the first die is successful. The method further includes performing a system test on the partial package including the first die and stacking a second die on the first die if the system test on the partial package and the first die is successful.