JEP139 Constant Temperature Aging to Characterize Aluminum

JEP139.pdf

Constant Temperature Aging to Characterize Aluminum Interconnect Metallization for Stress-Induced Voiding
JEP139  DECEMBER 2000

CONTENTS
Page
1 Scope 1
2 Introduction 1
2.1 Stress-induced voids 1
2.2 Void growth 2
2.3 Technology-dependent factors 2
2.4 Post processing factors 2
2.5 Void nucleation factors 3
2.6 Structures 3
2.7 Stress temperature 3
2.8 Void volume 3
3 Constant temperature aging test method 4
3.1 Constant temperature aging for stress-induced voids 4
3.2 Suggested procedure 4
3.3 Test structures 5
3.4 Test conditions, procedures, and measurements 6
3.5 Data interpretation 7
4 Precautions and interferences 9
4.1 Variation of resistance change 9
4.2 Copper solubility 10
4.3 Comparisions 10
4.4 Thermal cycling 10
4.5 Peak temperature 10
4.6 In situ measurements 10
4.7 Calculated void volume 11
4.8 Passivation deposition temperature 11
4.9 Joule heating 11
5 Data to be reported 12
6 References 12

1 Scope
This document describes a constant temperature (isothermal) aging method for testing aluminum (Al) metallization test structures on microelectronics wafers for susceptibility to stress-induced voiding.
This method is valid for metallization/dielectric systems in which the dielectric is deposited onto the metallization at a temperature considerably above the intended use temperature, and above or equal to the deposition temperature of the metal.
If the metallization is a single-alloy component, such as AlSi or AlCu, the failure criterion of the method is an open-circuit of the test structure. The failure criterion for layered metallizations
with refractory shunt layers (such as titanium (Ti), titanium nitride (TiN), tungsten (W), etc.) is a preselected percent increase in resistance of the test structure.
The method assumes that void growth and therefore resistance changes can be modeled, as described by Rauch and Sullivan [1, 2], to obtain an acceleration factor for void growth.
Although this is a wafer test, it is not a fast (less than 5 minutes per probe) test. It is intended to be used for lifetime prediction and failure analysis, not for production Go-NoGo lot checking.