SRAM Redundant Circuit Using Transistor Pairs for Defect Repair

Solution Overview

Problem

The existing redundant circuits for SRAM devices are complex and costly due to the requirement of fuse components, which increase design and development time and die size of memory IC chips.

Innovation Solution

A redundant circuit for SRAM devices is designed without using fuse components, utilizing pairs of transistors with different conductance and a redundancy control circuit to detect defective memory units and perform redundancy replacement, reducing complexity and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fuse components are used to implement redundant circuits, then reliability is improved through defect repair capability, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvedefect repair capabilityVSAvoidcircuit configuration complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the fuse component from the redundant circuit implementation. By removing the fuse component entirely and replacing it with a circuit using only transistors and capacitors, the solution reduces device complexity while maintaining the defect repair capability through alternative means (detecting voltage changes caused by defects and activating redundant circuits accordingly).

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention creates a functional copy of the fuse component's defect detection and repair initiation functionality using transistor-capacitor circuits. Instead of using physical fuses that are blown to indicate defects, the patent uses transistors and capacitors to detect voltage changes and trigger redundant circuit activation, achieving the same reliability function without the complexity of fuse components.

Inventive Principle:

Principle #26Copying

2Reliability

If fuse components are used to implement redundant circuits, then reliability is improved through defect repair capability, but manufacturing cost increases

Engineering Contradiction:

Improvedefect repair capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention extracts and eliminates the fuse component from the redundant circuit implementation. By removing the fuse component entirely and replacing it with a circuit using only transistors and capacitors, the solution reduces device complexity while maintaining the defect repair capability through alternative means (detecting voltage changes caused by defects and activating redundant circuits accordingly).

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces expensive fuse components with cheaper transistor and capacitor elements. Transistors and capacitors are standard, low-cost components in semiconductor manufacturing, whereas fuse components add additional manufacturing steps and costs. The transistor-capacitor circuit achieves the same defect detection and repair initiation functionality at lower manufacturing cost.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If fuse components are used to implement redundant circuits, then defect repair capability is provided, but die size increases

Engineering Contradiction:

Improvedefect repair capabilityVSAvoiddie size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The invention extracts and eliminates the fuse component from the redundant circuit implementation. By removing the fuse component entirely and replacing it with a circuit using only transistors and capacitors, the solution reduces device complexity while maintaining the defect repair capability through alternative means (detecting voltage changes caused by defects and activating redundant circuits accordingly).

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges the functions of defect detection and redundant circuit activation into a single integrated transistor-capacitor circuit. By combining these functions and eliminating the separate fuse component, the patent reduces the overall die size required for the redundant circuit while maintaining full defect repair capability.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10497431B2Static random-access memory device, redundant circuit thereof, and semiconductor device

Publication Date: 2019.12.03 POWERCHIP SEMICON MFG CORP

AI summary

A redundant circuit for a SRAM device is provided. The redundant circuit includes: a pair of a first transistor and a second transistor, connected between a power source voltage and a power source terminal of each of the input/output memory units, wherein the pair of the first transistor and the second transistor are connected in parallel with each other, and the first transistor has a greater mutual conductance than the second transistor; and a redundancy control circuit configured to detect a voltage of the power source terminal of each of the input/output memory units when the first transistor is turned off and the second transistor is turned on. When the detected voltage of the power source terminal is decreased by a predetermined value or more from a predetermined reference voltage, the input/output memory unit is determined in a defective state, and the input/output memory unit in the defective state is redundantly replaced with a normal input/output memory unit.