Method for testing instability of a negative bias temperature

Abstract

The invention discloses a method for testing instability of a negative bias temperature. The method comprises the following steps: determining the service life of a device under at least two different test negative biases, and determining a functional relationship between the test negative bias and the service life of the device in a fitting manner; calculating the service life of the device in a normal working state under a working negative bias according to the determined functional relationship; and comparing the calculated service life of the device with a pre-set threshold, wherein if the calculated service life is longer than the threshold, the test is passed. In the process of testing the service life of the device under different test negative biases, the test negative bias is reduced to the working negative bias before measuring a designated parameter of the device each time so as to avoid recovery of the device performance, ensure the accuracy of the measurement result and the accuracy of the entire test process and increase the processing speed of the entire test process; and moreover, compared with the prior art, only one important parameter of the device is tested in the scheme of the invention, and thus the test speed is further increased.

Description

technical field [0001] The invention relates to a semiconductor device testing technology, in particular to a testing method for negative bias temperature instability. Background technique [0002] In the existing semiconductor manufacturing process, after the device is manufactured, it is necessary to perform various reliability tests on the device, such as negative bias temperature instability (NBTI) test. Negative bias temperature instability means that when a negative bias is applied to the gate of the device, the performance of the device will degrade significantly under high temperature conditions, manifested as a decrease in saturation current (IDSAT) and an increase in threshold voltage (VT) Wait. When the performance of the device degrades to a certain level, the device becomes unusable. The purpose of the negative bias temperature instability test is to first determine the period of time from the beginning of use to the failure of the device, that is, the life of...

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Problems solved by technology

During the Delay Time, the performance of the device will recover to a certain extent. For example, after applying a negative bias voltage for a period of time, if the saturation current of the device is directly measured, the value should be 95mA, but due to the existence of the Delay Time, Wait until the actual measurement may have been restored to 98mA, resulting in inaccurate measurement results, which in turn lead to inaccuracy of the entire test process; moreover, the existence of Delay Time also slows down the processing speed of the entire test process

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