Software-Enabled Wafer-Level Reliability Testing for Next-Gen Semiconductors

A key measure driving performance in semiconductor integrated circuits (ICs) is reliability. As ICs continue to become smaller and chip complexity increases, manufacturers need to ensure they can continue to provide the same level of reliability to their customers for mission-critical end applications.

While wafer level reliability tests have long been used to provide insights into variability in processes and degradation, these increased demands from new technology trends and chip complexity drive engineers to look for methods to increase reliability test data while decreasing cost. Current approaches make tradeoffs between channel count and flexibility but a parallel per pin approach is necessary to address both.

Wafer Level Reliability (WLR) Test Overview

Along the lifetime of an IC, there are two clear times when an increased failure rate is expected: in the beginning with defects during the manufacturing process and at the end as the IC begins to wear out. Optimizations to the production process increase yield but do not help understand what causes products to wear out earlier than expected. Reliability testing gives insight into what processes or mechanisms could cause premature IC failure and estimates the lifetime of an IC.

The typical method used in reliability testing involves operating the device at its usable limits (often around temperature and voltage) to force it to wear out and model its lifetime against known failure mechanisms. These tests are done on built-in structures in the wafer to gather data and ensure it can be done earlier in the manufacturing process.

Test Setup

The failure mechanics usually tested comply with Joint Electron Device Engineering Council (JEDEC) standards for common WLR stresses. They include time-dependent dielectric breakdown (TDDB),hot carrier induced degradation (HCI), and bias temperature instabilities (BTI/NTBI). The wiring setup to test these mechanics on transistors in a wafer includes four source measure units (SMUs), each tied to the .