Method and apparatus for measuring gate leakage current in an integrated circuit

• US 6,348,806 B1
• Filed: 03/18/1999
• Issued: 02/19/2002
• Est. Priority Date: 03/18/1999
• Status: Expired due to Fees

• Current Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Okandan, Murat, Campbell, Jules D. Jr.
• Primary Examiner(s): Nguyen, Vinh P.
• Application Number:
  US09/271,892
• Time in Patent Office: 1,069 Days
• Field of Search: 324/765, 324/763, 324/719, 324/613, 324/520, 324/158.1, 324/73.1, 438/14, 438/18, 438/17, 257/40, 257/48, 714/733, 714/734
• US Class Current: 324/750.3
• CPC Class Codes: G01R 31/2621 for testing field effect transistors, i.e. FET's
• CPC Class Codes: G01R 31/275 for testing individual semiconductor components within integrated circuits

Abstract

An integrated circuit (10) includes a measurement circuit (20) for determining if a transistor (26) has normal gate leakage current or has a gate leakage current which is greater than normal. A transistor such as transistor (26) may be in a condition known as quasi-breakdown which typically occurs in response to some electrical stress. The characteristic of quasi-breakdown is that there is a very significant increase in gate leakage current, the transistor continues to function as a transistor but perhaps with degraded performance, and the transistor will fail if it continues to receive the stresses that caused it to go into quasi-breakdown. Thus, the measurement circuit (20), which is included on the integrated circuit (10), provides an early warning that a transistor, a device under test (26), is going to fail if the operating conditions remain the same.

Claims

1. An integrated circuit, comprising:

a first circuit; and

a measurement circuit coupled to the first circuit, the measurement circuit adapted to measure gate leakage current of the first circuit, the measurement circuit comprising a quasi-breakdown indication means, the quasi-breakdown indication means adapted to provide a quasi-breakdown indication when the gate leakage current exceeds a predetermined threshold;

wherein the measurement circuit comprises a current-to-frequency converter; and

wherein the current-to-frequency converter comprises;

a current controlled oscillator, comprising;

a first current integrator adapted to integrate the gate leakage current into an input voltage;

a first comparator adapted to compare the input voltage to a reference voltage;

a latch coupled to an output of the first comparator and having an output; and

a first charging circuit coupled to the first current integrator, the first comparator, and the output of the latch.

2. The integrated circuit of claim 1, wherein the first current integrator is a capacitive device.

3. The integrated circuit of claim 1, wherein the current controlled oscillator further comprises:

a current mirror which is coupled to the first circuit.

4. An integrated circuit, comprising:

a first circuit; and

a measurement circuit coupled to the first circuit, the measurement circuit adapted to measure gate leakage current of the first circuit, the measurement circuit comprising a quasi-breakdown indication means, the quasi-breakdown indication means adapted to provide a quasi-breakdown indication when the gate leakage current exceeds a predetermined threshold;

wherein the measurement circuit comprises a current-to-frequency converter; and

wherein the current-to-frequency converter comprises;

a current controlled oscillator, comprising;

current integrator means for integrating the gate leakage current into an input voltage;

comparator means for comparing the input voltage to a reference voltage and providing an output;

latch means, coupled to the comparator means, for latching the output of the comparator means; and

charging means, coupled to the current integrator means, for discharging the current integrator means in response to the latch means.