On-Wafer Test Circuitry with Tunable Threshold Voltage

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Solution Overview

Problem

Existing on-chip test-only circuitry for integrated circuits (ICs) faces challenges in operating properly across a wide range of test conditions without limiting the speed of functional circuitry and minimizing current draw during normal operation.

Innovation Solution

The implementation of on-chip test-only circuitry using fully depleted silicon-on-insulator (FDSOI) transistors with tunable threshold voltage characteristics, driven by on-chip bias generators, allows independent modulation of threshold voltages to optimize performance and reduce leakage power, ensuring proper operation across various test conditions without impacting functional circuit speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If on-chip test-only circuitry is used to test functional circuitry across a wide range of test conditions, then testing robustness is improved, but current draw during normal operation increases

Engineering Contradiction:

Improvetesting robustnessVSAvoidcurrent draw during normal operation

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent extracts the test-only circuitry from the functional circuitry by providing separate drive circuitry (second drive circuitry) dedicated solely to controlling the test-only circuitry. This separation allows the test circuitry to be independently controlled and powered, enabling it to be disabled during normal operation to minimize current draw while maintaining availability for testing operations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent implements dynamic control of the test-only circuitry through separate drive circuitry that can independently modulate its operation. The second drive circuitry can adjust the operating conditions of the test-only circuitry based on whether testing is required, allowing the system to adapt its power consumption characteristics to match actual operational needs.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If on-chip test-only circuitry is driven independently to ensure proper operation across test conditions, then testing accuracy is improved, but device complexity increases

Engineering Contradiction:

Improvetesting accuracyVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the control functions by providing separate drive circuitry for the test-only circuitry. The second drive circuitry is specifically dedicated to controlling test operations, while the first drive circuitry handles functional circuitry. This segmentation allows independent optimization of test control without affecting functional circuit operation, improving testing accuracy while organizing complexity into manageable, separated components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second drive circuitry acts as an intermediary between the control logic and the test-only circuitry. This intermediary layer provides specialized control functions tailored to test operations, enabling accurate testing across various conditions while isolating the complexity of test control from the functional circuitry control paths.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If separate drive circuitry is used for test-only circuitry to operate independently, then operation independence is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveoperation independenceVSAvoidmanufacturing complexity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent segments the drive circuitry into first drive circuitry for functional circuitry and second drive circuitry for test-only circuitry. This segmentation enables independent operation and configuration of test functions while maintaining standard integrated circuit manufacturing processes, as all components are fabricated together in the same IC structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The separate second drive circuitry provides multi-functionality by serving both normal operational control and test mode control for the test-only circuitry. This universal control path allows the same hardware structure to adapt to different operational requirements without requiring additional specialized manufacturing processes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10254340B2Independently driving built-in self test circuitry over a range of operating conditions

Publication Date: 2019.04.09 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

Embodiments are directed to a semiconductor wafer having on-wafer circuitry. The on-wafer circuitry includes functional circuitry and first drive circuitry communicatively coupled to the functional circuitry. The on-wafer circuitry further includes test-only circuitry communicatively coupled to the functional circuitry, along with second drive circuitry communicatively coupled to the test-only circuitry. The control circuitry is communicatively coupled to the second drive circuitry and the test-only circuitry, wherein the first drive circuitry is configured to drive the functional circuitry in a first manner, and wherein the control circuitry is configured to control the second drive circuitry to drive the test-only circuitry in a second manner that is independent of the first manner.