Session 4.3: Optimization of Backend Testing

Optimization of Backend Testing aims at reduction of time/cost, Better Quality , reliability and higher yields . The optimization of testing involves optimizing test conditions, test flow, test content and test limit based on past data using AI/ML Algorithms. These Algorithms are used to predict the test flow, conditions and test limits for each die on wafer.

This paper discuss about different techniques and methodologies for optimization. These are applied at different stages of testing like Wafer Probe Test, Pre-Package Test, Post Package Test, Post Burn-in Test and In System Test. The techniques might include the most failed test cases, Golden Test cases, unstable Test cases and High Priority Test cases. These techniques could be configured for (1) Wafer or Lot or Die level data , (2) timelines for past data. These configurations could be appropriately chosen based on stages of testing.

-Different test flows would be predicted across different areas/dies in Wafer
-Test Flows would be optimized compared to full flow
-Minimum to stringent flow would be predicted for different dies, wafers and lots
-Redundancy on test will be removed
-Re-ordering of tests (arrange the test flow to screen out the major failures early in the flow),
-Sample testing of €œalways passing€ tests, or potentially even removing them manufacturing for Test Conditions
-Test content /conditions/limits will be optimized for lots, wafers and possibly for dies based on past data
-Test time reduction opportunities result from reducing the test content, changing test limits or performing a more efficient search for outliers.

The objective of paper is to discuss about each methodology and technique used for test and flow optimization. This will help to choose the appropriate methodology and techniques at different stages of Backend testing. As AI/ML algorithms are used for prediction , these could be finetuned over a period for accuracy. Utilizing these optimization can provide substantial quality, yield and cost advantages