Shift Register Controller for Flexible Column Address Repair
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Solution Overview
Problem
Laser-based fuse layouts in semiconductor devices are inefficient in terms of area usage, requiring large openings that restrict the placement of metal lines and logic gates, and previous counter-based solutions struggle with counting arbitrary numbers of fuses, especially when they are not powers of two, making it difficult to implement flexible column address repair circuits.
Innovation Solution
A shift register chain that shifts fuse information from outside to inside the column area, using an internally generated clock and a pre-programmed stop code to automatically stop shifting, independent of the number of bits, allowing for flexible placement and reduced area consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a counter-based shift register is used to count exactly the number of fuses, then the shifting can stop at the correct position, but the device complexity increases and adaptability decreases when the number of fuses is not a power of two
Solution Approach 1:
The patent changes the control parameter from counting the total number of fuses to counting only the meaningful data bits (excluding stop code bits). This parameter change simplifies the counter design and makes the system adaptable to different fuse configurations without requiring complex reprogramming.
Solution Approach 2:
The patent introduces stop code bits as an intermediary mechanism between the data bits and the counter. These stop codes serve as delimiters that enable the counter to automatically determine when to stop shifting without needing to know the total number of fuses in advance, thereby reducing counter complexity.
2Adaptability or versatility
If the number of counter bits is increased to handle arbitrary numbers of fuses, then the counting capability improves, but the area consumption increases
Solution Approach 1:
The patent changes the counting parameter from total fuse count to meaningful data bit count. This reduces the number of counter bits required, thereby reducing the counter circuit area while maintaining adaptability to handle arbitrary numbers of fuses through the stop code mechanism.
3Quantity of substance
If fuse block area is increased to accommodate all fuses, then all fuse information can be stored, but the area efficiency decreases and layout flexibility is reduced
Solution Approach 1:
The patent segments the fuse block into meaningful data bits and stop code bits. This segmentation allows the shift register to process only the necessary data portions while using compact stop codes to delimit data groups, thereby reducing the effective area required for fuse information storage and improving layout flexibility.
Solution Approach 2:
The patent extracts the stop code information from the main data stream and uses it as a separate control mechanism. This extraction allows the system to identify data boundaries without requiring additional area for explicit length indicators, thereby optimizing fuse block area usage.
4Adaptability or versatility
If the counter is reprogrammed for different column address fields, then the circuit can adapt to different configurations, but the ease of operation decreases due to programming difficulty
Solution Approach 1:
The patent changes the adaptation mechanism from reprogramming counter limits to using fixed stop code patterns. This makes the circuit adaptable to different configurations simply by changing the stop code values, which is much easier than reprogramming entire counter circuits, thereby improving ease of operation.
Data Source
AI summary
A column repair circuit uses a system of circuits that automatically stops the shifting of register contents independently of the number of bits to be shifted. The circuit is only dependent on the number of bits in a column address repair block. By adding shift register positions to one end of each shift register chain, a dedicated block of bits is used to detect the end of the shift chain without explicitly knowing the length of the chain. The shift register positions provide a hard-programmed code that can be used to stop the shifting of data automatically. The shift register positions also provide a space for hard-programmed code bits that can be examined to determine when the shift process ends. A shift chain can be controlled with a controller so long as the information is organized into groups of ‘k’ bits. The controller only requires information regarding the value of the number ‘k’ and the pre-programmed stop code in order to control any number of bits in a shift chain.