Semiconductor Memory Repair Using Test Control Block
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Solution Overview
Problem
Conventional semiconductor memory devices face challenges in repairing failed cells after packaging, as laser fuses cannot be programmed post-packaging, and E-fuses are one-time program cells, limiting the ability to perform redundancy operations after the device is fabricated.
Innovation Solution
Incorporating a nonvolatile memory block and a test control block that allows for the generation and testing of control signals during a program mode without actually programming the nonvolatile memory cells, enabling the determination of normal operation and storage of repair data for redundancy operations without consuming nonvolatile memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser fuses are used to store repair data, then the device can perform redundancy operations during wafer state, but the laser fuses cannot be programmed after packaging and the cells cannot be recovered
Solution Approach 1:
The patent changes the programming method parameter from laser-based physical fusion to electrical pulse-based E-fuse mechanism, enabling programming both during wafer state and after packaging. This parameter change allows the same storage mechanism to function in both manufacturing and post-packaging scenarios.
Solution Approach 2:
The patent implements preliminary testing of the E-fuse array during wafer state before final packaging, allowing identification and replacement of defective cells in advance. This preliminary action ensures that only functional E-fuses are used for storing repair data after packaging.
2Adaptability or versatility
If E-fuses are used to store repair data, then the device can be programmed after packaging, but the E-fuses are one-time program cells that cannot be recovered to original state
Solution Approach 1:
The patent creates a copy of the repair data storage function by implementing a test mode that reads from and writes to E-fuses without permanently altering them. This copying mechanism allows verification of E-fuse functionality and data storage capability while preserving the ability to recover and reuse the same E-fuses.
Solution Approach 2:
The patent introduces a dynamic test mode that can switch between different operational states (testing vs. normal operation) of the E-fuse array. In test mode, the system can perform read/write operations without committing permanent changes, allowing the system to adapt its behavior based on whether it needs to verify functionality or perform actual repair data storage.
3Reliability
If a test mode is added to verify nonvolatile memory operation, then the system can determine normal operation without direct programming, but the device complexity increases
Solution Approach 1:
The patent implements a test control block that serves multiple functions: it can test E-fuse array functionality, verify nonvolatile memory operation, and support both wafer state and post-packaging operations. By making the test control block multi-functional, the patent reduces the need for separate dedicated test circuits for each function.
Solution Approach 2:
The test control block acts as an intermediary between the external test equipment and the E-fuse array, enabling verification of normal operation without requiring direct programming. This intermediary layer allows the system to test functionality through controlled read/write operations while isolating the complex testing logic from the actual memory cells.
4Adaptability or versatility
If nonvolatile memory cells are used for storing repair data, then redundancy operations can be performed after fabrication, but the cells are consumed during testing
Solution Approach 1:
The patent performs preliminary testing of the E-fuse array during wafer state before final packaging and data storage. This preliminary action identifies and replaces defective cells in advance, ensuring that only functional E-fuses are used for storing repair data after packaging, thereby preventing cell consumption during subsequent testing.
Solution Approach 2:
The patent creates a copy of the repair data storage function by implementing a test mode that reads from and writes to E-fuses without permanently altering them. This copying mechanism allows verification of E-fuse functionality and data storage capability while preserving the ability to recover and reuse the same E-fuses, preventing cell consumption.
Data Source
AI summary
A semiconductor device includes a nonvolatile memory block suitable for outputting data stored in a plurality of nonvolatile memory cells included therein based on first control information, and programming data in the nonvolatile memory cells based on second control information; a control block suitable for generating the first control information based on an initialization signal, wherein the control block sequentially generates the second control information and the first control information when a program mode is activated; and a test control block suitable for deactivating the nonvolatile memory block and determining whether at least one control signal among a plurality of control signals included in the first and second control information is normally generated, in a test operation on the program mode.