Browse Prior Art Database

Method to Predict Variability in the TDDB Lifetime Behavior of Dual Damascene Structures

IP.com Disclosure Number: IPCOM000240894D
Publication Date: 2015-Mar-10
Document File: 2 page(s) / 45K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a non-destructive approach for predicting the time dependent dielectric breakdown (TDDB) of the dielectric material that separates the copper (Cu) lines in dual damascene structures. The method determines the TDDB Beta value by determining the variability in the initial current at a voltage below which TDDB failure occurs.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 51% of the total text.

Page 01 of 2

Method to Predict Variability in the TDDB Lifetime Behavior of Dual Damascene Structures

One of the main reliability concerns for copper (Cu) interconnects is time dependent dielectric breakdown (TDDB) of the dielectric material that separates the Cu lines. Predicting the TDDB lifetime behavior typically involves stressing at high voltage conditions and measuring the time for the dielectric material to fail when an electrical short occurs between two Cu lines. The variability of the failure times at a given stress condition is determined by the Beta value of the Weibull distribution, where large Beta values indicate small variability in the failure times.

Since completing these TDDB stresses is time consuming, perhaps as long as several days, information about the Beta value cannot be obtained until after the wafers are fully processed and tested for reliability. Although voltage ramp testing can be used to obtain similar information in a shorter amount of time as compared to TDDB stresses, this testing can take several hours for a given structure. In addition, both TDDB and voltage ramp testing are destructive methods. To enable more efficient process development, a non-destructive method that requires a short amount of time is needed for predicting the TDDB Beta value.

The novel idea is to use the variability in the initial current at a given voltage as a measure of the expected TDDB Beta value. Since the initial current is related to the spacings between the Cu lines, increased variability in the spacings leads to increased variability in the initial current values. Since the spacings between the Cu lines ultimately determines the TDDB lifetime behavior, the variability in the initial curre...