Integrated Capacitor Testing Circuitry for Defect Detection

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Solution Overview

Problem

Integrated capacitors in ICs are prone to manufacturing defects, such as variations in electrode spacing, which can lead to increased electric field strength, leakage current, and premature failure, making it challenging to detect defects and ensure capacitance compliance during automated testing.

Innovation Solution

A testing circuitry that applies a high test voltage to the integrated capacitor, monitoring charge transfer and leakage current using an integrator and operational amplifier, allowing for the detection of defects and capacitance measurement, even when only one terminal is accessible, and is compatible with conventional automated testing equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If integrated capacitors are formed with interdigitated electrodes to achieve high capacitance values and high voltage operation, then capacitance density and voltage handling capability are improved, but manufacturing defects causing electrode spacing variations lead to increased leakage current and reduced reliability

Engineering Contradiction:

Improvecapacitance valueVSAvoiddefect detection capability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies preliminary action by performing defect detection testing on integrated capacitors before they are integrated into the final IC product. The test circuitry charges the capacitor to a test voltage and monitors charge transfer to detect manufacturing defects such as electrode spacing variations, dust particles, or lithographic defects that could cause leakage current or premature failure in high-voltage operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses an intermediary test circuitry that includes a first capacitor and charge monitoring circuit to indirectly detect defects in the integrated capacitor under test. The first capacitor is charged to a test voltage and then connected to the integrated capacitor, allowing monitoring of charge transfer to detect defects without requiring direct measurement of the integrated capacitor's internal structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If discrete capacitors are used instead of integrated capacitors, then reliability and electrical performance are improved, but device area and cost increase

Engineering Contradiction:

Improvecapacitor performanceVSAvoidcircuit area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent makes the integrated capacitor serve multiple functions: it performs its primary capacitance function in the circuit while also being testable through the same integrated structure. The test circuitry utilizes the capacitor's existing terminals and structure, allowing defect detection without adding separate discrete capacitor components, thus maintaining area efficiency while enabling reliability verification.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If automated testing is implemented to detect manufacturing defects, then reliability is improved, but test complexity and time increase

Engineering Contradiction:

Improvedefect detection accuracyVSAvoidtesting time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent extracts the defect detection function from complex multi-step testing procedures and implements it through a simplified charge transfer measurement. By monitoring the charge transfer from the first capacitor to the integrated capacitor during a single charging cycle, the test circuitry efficiently detects manufacturing defects without requiring prolonged testing time or complex measurement sequences.

Inventive Principle:

Principle #2Taking out (Extraction)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method effectively identifies defects and measures capacitance, increasing the reliability of integrated capacitors by detecting anomalies that may not cause a complete short circuit, ensuring compliance with specifications, and improving manufacturing consistency.

Implementation Method 1

a first capacitor, a supply node for connecting to a voltage supply... in which the first capacitor is connected to the supply node and is disconnected from the test node so as to charge the first capacitor to a test voltage

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

The charge monitoring circuit is configured to monitor a charge transfer from the first capacitor to the integrated capacitor in said second state

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11467204B2Testing an integrated capacitor

Publication Date: 2022.10.11 SEMTECH CORP

AI summary

Circuitry for testing an integrated capacitor that includes a first capacitor, a supply node for connecting to a voltage supply, a test node for connecting to the integrated capacitor, and a charge monitoring circuit. The circuitry is operable in a sequence of states including a first state in which the first capacitor is connected to the supply node and is disconnected from the test node so as to charge the first capacitor to a test voltage and a second state in which the first capacitor is disconnected from the supply node and is connected to the test node to apply the test voltage to the integrated capacitor. The charge monitoring circuit is configured to monitor a charge transfer from the first capacitor to the integrated capacitor in said second state and to generate a measurement value based on an amount of the charge transfer.