Memory Testing: MBIST, BIRA & BISR | An Insight into Algorithms and Self-Repair Mechanism

 Memory testing plays a crucial role in the semiconductor engineering industry, especially with the increasing demand for deep submicron devices and the rapid growth of IoT devices. These devices require lower area and fast access time, making an automated testing strategy essential to reduce time and cost. However, conventional design-for-test (DFT) methods do not provide a complete solution for testing memory faults and their self-repair capabilities.

In this article, we will explore Memory BIST (Built-in Self-test) as a promising solution to this dilemma. Memory BIST and its Importance: Memory BIST is a self-testing and repair mechanism that adds test and repair circuitry directly to the memory itself. It utilizes algorithms to detect various memory faults such as stuck-at, transition delay, coupling, and neighborhood pattern-sensitive faults. By integrating the testing and repair functions within the memory chip, Memory BIST significantly reduces the need for external test patterns and improves yield.

The Challenges of Memory Testing: Testing memories presents unique challenges compared to testing standard logic designs. Fault models differ in memory arrays due to their distinctive structure. Additionally, testing memories at the system design level requires complex test logic to multiplex and route memory pins to external pins. The size and density of the cell array further complicates functional testing or ATPG (Automatic Test Pattern Generation).