Fuse Disposing Circuit for Stable Test Mode in Semiconductor Memory
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Solution Overview
Problem
Conventional semiconductor memory device circuits fail to maintain a stable test mode after a fuse is cut, leading to an inability to perform further tests due to unstable voltage levels and lack of practical test mode application.
Innovation Solution
A circuit and method that include a test mode enable confirmation section, fuse sets providing constant signals regardless of fuse elimination, and a decoder for decoding output signals from multiple fuse sets, ensuring test mode functionality even after the fuse is cut by using a test mode enable confirmation section and comparator to output different logic signals based on fuse existence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fuse is cut during test mode to adjust target values, then manufacturing precision is improved, but the test mode becomes unstable and cannot continue after fuse cutting
Solution Approach 1:
The circuit is divided into separate functional blocks: a test mode signal generation unit that operates independently from the fuse cutting unit. This segmentation allows the test mode signals to continue being generated and maintained even after the fuse is cut, resolving the contradiction between achieving precise target value adjustment through fuse cutting and maintaining test mode stability for continued testing.
2Manufacturing precision
If the fuse is cut to ensure stable operation with respect to manufacturing variations, then manufacturing precision is improved, but the ability to perform further tests is lost
Solution Approach 1:
The test mode signals are generated and prepared in advance through dedicated signal generation circuits before fuse cutting occurs. These pre-generated signals are designed to maintain their functionality even after the fuse is cut, allowing the test mode to continue operating stably and enabling further tests to be performed without interruption.
3Manufacturing precision
If conventional fuse cutting method is used to adjust target values, then manufacturing precision is improved, but device complexity increases due to additional circuit requirements
Solution Approach 1:
The test mode signal generation functionality is extracted as a separate, independent circuit block from the main fuse cutting operation. This extracted signal generation unit can operate autonomously and provide stable test mode signals regardless of the fuse cutting status, thereby achieving precise target value adjustment without significantly increasing overall device complexity.
Data Source
AI summary
A fuse disposing circuit executes a same test as in a state before a fuse is cut, even in case the fuse is cut. For this, the fuse disposing circuit in accordance with the invention includes a test mode enable confirmation section for informing whether a test mode is enabled; and a fuse set for providing a constant signal by using the output from the test mode enable confirmation section in case of the test mode, regardless of elimination or non-elimination of a fuse.