Non-Volatile Memory Diagnosis Using BIST Compression
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Solution Overview
Problem
The existing methods for diagnosing non-volatile memory, such as Flash memory, require external devices and additional non-volatile memory to store expected values, leading to increased overhead and complexity, especially during start-time diagnosis, due to the causal link dilemma of generating new expected values when storing them in the diagnosis target memory.
Innovation Solution
A semiconductor device with a Built-In Self-Test (BIST) circuit that includes a reading circuit and a compressor, which generates addresses and compresses data using a predetermined algorithm, allowing for self-diagnosis without external devices by using a reservation address to store previously calculated fixed data, enabling the convergence of compression values to a fixed value for diagnosing the non-volatile memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expected value is stored in the diagnosis target non-volatile memory, then the memory can be diagnosed, but a new expected value is generated causing a causal link dilemma
Solution Approach 1:
The non-volatile memory is segmented into a diagnosis target area and a storage area for expected values. The BIST circuit reads data from the diagnosis target memory, compresses it to generate a signature value, and compares it with the expected value stored separately in the same memory's reserved region, thereby avoiding the causal link dilemma by spatial separation of diagnosis objects and reference data.
Solution Approach 2:
The patent introduces an intermediary mechanism where the BIST circuit performs compression calculation on read data and generates a signature value, which then serves as the basis for comparison with the expected value. This intermediary signature value generation process decouples the direct causal link between storing expected values and the diagnosis target data.
2Reliability
If another non-volatile memory is provided to store expected value, then the diagnosis can be performed, but overhead increases and the additional memory becomes out of diagnosis target
Solution Approach 1:
The non-volatile memory serves multiple functions: it acts as both the diagnosis target (storing data to be diagnosed) and the storage medium for expected values. The BIST circuit is designed to selectively access different regions of the same memory - reading diagnosis target data from one region and comparing the compressed result with expected values from another region, thereby eliminating the need for separate diagnosis memory and reducing overall system overhead.
Solution Approach 2:
The patent merges the diagnosis target memory and the expected value storage into a single non-volatile memory device. The memory is organized with distinct address spaces: one for diagnosis target data and another for pre-stored expected values. This merging approach reduces the total quantity of memory components while maintaining full diagnosis capability through intelligent address management and selective access.
3Reliability
If external device is used to store expected value and compare diagnosis result, then diagnosis can be performed, but system design overhead increases
Solution Approach 1:
The BIST circuit is designed to perform self-service diagnosis within the non-volatile memory system. It autonomously reads data from the diagnosis target region, compresses the data using a compression algorithm, generates a signature value, retrieves the expected value from the stored region, and compares the two values to determine diagnosis results. This self-contained approach eliminates the need for external testing devices and reduces system design overhead by integrating all diagnosis functions within the memory device itself.
Data Source
AI summary
There is to provide a semiconductor device capable of realizing a start time diagnosis on a non-volatile memory without any external device and any non-volatile memory out of a diagnosis target. The non-volatile memory includes an address space formed by addresses continuously read and a reservation address formed by a single or a plurality of addresses, read after the address space. A previously calculated value fixed data is stored in the reservation address. When all the data stored in the address space and the value fixed data are compressed using a predetermined initial value according to a predetermined compression algorithm, the value fixed data is the data for converging the compression value to a predetermined fixed value (for example, 0).