ESREF 2006 EUFANET workshop Localization of Electrical Shorts in Dies and Packages using Magnetic Microscopy and Lock-in-IR Thermography M. Hechtl, G. Steckert, C. Keller, (A. Altes) Infineon Technologies Failure Analysis Otto-Hahn-Ring 6 D-81739 Munich

Outline Introduction to background „ Measurement techniques „ Results for different packages „ Outlook on application areas „ Conclusion „

Evolution of semiconductor technology A) Silicon level: Higher density of active areas results in higher complexity of die metallization. Metal 6 2-layer metallization

Evolution of package technology System in Package

7-layer PCB

Need for localization B) Increasing complexity in package design: - more than one die (system-in-package) - multilayer package metallization

Increasing demand for package-level analysis tools

Standard analysis techniques for packages SAM X-ray

x TDR

New analysis technique: SQUID for Magnetic Microscopy (SSM)

Resolution ~ d/4 Sensitivity max. 150nA for d~50µm

d

Typical: I > 100µA d~200µm

Circular magnetic field around current

Magnetic microscopy (1)

z

y x

(2) Bz(x,y)

Fast Fourier Transformation ~ 1sec

I(x,y)

New analysis technique: Lock-In-IR-Thermography (LIT):

Image source: Thermosensorik GmbH Erlangen

Result for TSSOP 1) Short in TSSOP package. (Particle invisible in x-ray; decapsulation would have destroyed the failure.) Current in failure mode: 670µA

Result for SIP 2) System in Package Failure attributed to certain die; no decapsulation, repackaging and testing of other dies needed.

Die effected by the short Current in failure mode 1,2mA

Result for ESD failure 3) Failure not in package, but on Si level.

Current in failure mode 370µA

Result for DRAM module 4) DRAM module

Current: 3mA

Overlayed current distribution

Result for DRAM module SSM and LIT results

White outlined areas about 400µm x 600µm

SSM

LIT

Short prepared by FIB

Outlook: Synergy potential LIT: Projection of a hot spot from unknown layer into image plane.

SSM: Projection of 3D current path into 2D image plane.

+ Layer 1 Layer 2 Layer 3

3D failure location at cross section of 3D current path and hot spot projection line.

Conclusion Technological trend: - Increasing number of devices in one package & - increasing complexity in package wiring. --> Analysis tools for packages are becoming more important. Failure analysis response: „ Magnetic Microscopy with SQUID sensor visualizes package current paths. By comparison with pass device or layout, package failures may often be localized or attributed to a certain device. „ For IR-transparent packages, combination of SSM with Lock-InIR Thermography provides the possibility, to project the hot spot detected by LIT, upon the current path of the SSM measurement. This may allow faster failure localization in the case of complex layouts. Acknowledgement: L. Alexa, J. Strobel, A. Winterstein and S. Chu for sample preparations and example images.