Shared Relief Information Storage for Semiconductor Redundancy
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Solution Overview
Problem
As the scale of semiconductor systems increases, the area required for redundancy schemes in memory chips grows, leading to increased chip area and transfer time for relief information, along with complex control mechanisms due to the need for multiple scan flip-flops and separate relief information storing units for each redundant memory.
Innovation Solution
A semiconductor device design where a shared second relief information storing unit outside the redundant memory allows multiple redundant memories to operate independently, reducing the number of relief information storing units and simplifying transfer control, with shift registers for serial information transfer and shared relief information across memories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate relief information storing unit (scan flip-flop) is provided in each redundant memory, then each redundant memory can operate independently, but the chip area increases and the number of storing units increases in proportion to the number of redundant memories
Solution Approach 1:
The patent applies universality by making the second relief information storing unit (located in the fuse box) serve multiple redundant memories simultaneously. Instead of having dedicated storing units for each redundant memory, a single shared storing unit in the fuse box provides relief information to any of the plurality of redundant memories, thereby reducing the total number of storing units and chip area while maintaining independent operation capability.
Solution Approach 2:
The patent introduces an intermediary mechanism - the shared second relief information storing unit in the fuse box - that mediates between the relief information source and multiple redundant memories. This intermediary allows efficient information distribution to multiple targets without requiring separate storing units for each, thus reducing area while preserving functional independence.
2Loss of information
If scan flip-flops are connected in a daisy chain for serial transfer of relief information, then relief information can be transferred from the fuse box to redundant memories, but the transfer time increases in proportion to the number of scan flip-flops in the chain
Solution Approach 1:
The patent segments the relief information transfer process into two distinct phases: (1) parallel loading of relief information into the shared second storing unit in the fuse box, and (2) sequential distribution to individual redundant memories only when needed. This segmentation avoids the problem of sequentially transferring information through a long daisy chain, as the shared storing unit can quickly distribute information to any redundant memory without being constrained by chain length.
3Adaptability or versatility
If the number of scan flip-flops varies depending on the structure of each redundant memory, then each redundant memory can have customized relief capacity, but complicated control is required for shifting operations
Solution Approach 1:
The patent applies universality by providing a standardized shared second relief information storing unit in the fuse box that serves all redundant memories regardless of their individual structures. This universal storing unit eliminates the need for varied scan flip-flop configurations and complex control logic, as it can uniformly manage relief information for any number or type of redundant memories on the chip.
Data Source
AI summary
In a semiconductor device having a redundant memory, the area of the device is reduced and a time required to transfer relief information is reduced. Moreover, a transfer control of relief information is facilitated. A first relief information storing unit stores relief information for relieving a redundant memory having a defective cell. A plurality of redundant memories share a second relief information storing unit. The second relief information storing unit is connected in series to the first relief information storing unit. The relief information is transferred from the first relief information storing unit to the second relief information storing unit.