Roll Call Circuit Serial Address Output for Memory Defect Evaluation
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Solution Overview
Problem
Existing semiconductor devices require multiple address inputs during roll call operations, making evaluation and identification of defective memory cells time-consuming and inefficient.
Innovation Solution
A semiconductor device with a roll call circuit that outputs the address of a defective memory cell directly to the outside in a serial manner, using a fuse circuit and access control circuit to replace defective cells with redundant ones, reducing the need for multiple address inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all addresses are input to the semiconductor device during roll call operations, then the hit signal can be output to identify defective memory cells, but the evaluation time becomes excessively long
Solution Approach 1:
The invention extracts and outputs the address information stored in the fuse circuit directly to the outside world through a dedicated output terminal. This allows the defective memory cell addresses to be read without requiring the traditional roll call operation that inputs all addresses, thereby significantly reducing evaluation time while maintaining identification accuracy.
Solution Approach 2:
The address information is pre-stored in the fuse circuit during the manufacturing process when defective cells are identified. This preliminary storage of address data enables direct output of defective cell addresses during evaluation, eliminating the need for time-consuming iterative address input operations.
2Measurement precision
If a roll call circuit outputs the hit signal to identify defective cells, then defective memory cell addresses can be determined, but multiple address inputs are required which increases operational complexity
Solution Approach 1:
The invention extracts the address information from the fuse circuit and outputs it directly through a dedicated terminal. This extraction approach simplifies the operation by eliminating the need for multiple address inputs and hit signal generation, allowing users to simply read the output address to identify defective cells.
3Device complexity
If the address of defective memory cell is output directly in serial manner, then the number of external terminals is minimized, but the output speed may be limited by serial transmission
Solution Approach 1:
The invention uses serial transmission to output address information, which minimizes the number of external terminals required. The address bits are transmitted periodically over time through a single output terminal, achieving a balance between reducing device complexity and maintaining acceptable output speed for evaluation purposes.
Data Source
AI summary
A semiconductor device that includes a plurality of memory cells assigned with addresses that are different from each other, a redundant memory cell replacing a defective memory cell among the memory cells, a fuse circuit storing an address of the defective memory cell, an access control circuit accessing the redundant memory cell when the address of the defective memory cell stored in the fuse circuit is supplied, and a roll call circuit outputting the address of the defective memory cell to outside the semiconductor device in a serial manner.