Acoustic imaging of bump defects in flip-chip devices using split spectrum analysis

Abstract

In this paper the performance of multi-narrow-band spectral analysis was evaluated concerning defect detection in microelectronic components with flip-chip contacts. Today, flip-chip technology is widely applied for interconnecting silicon dies to a substrate within high-end semiconductor packaging technologies. The integrity of the bump solder interconnection is of major concern for the reliability in this technology. Non-destructive defect localization and analysis of the flip-chip interconnections operating in a semi-automated mode is strongly desired. Scanning acoustic microscopy (SAM) combined with subsequent signal analysis has high potential for non-destructive localization of defective flip-chip interconnects. Analyzing multiple narrow spectral bands of signals acquired by a scanning acoustic microscope enabled the identification and localization of defective flip-chip interconnects. In the current study a 180 MHz transducer with 8 mm focal length was employed f or acoustic data acquisition by SAM. Those data were then analyzed off-line by discrete Fourier transformation, chirp z-transform and cosine transform using custom made MATLAB software. Through multi-narrow band spectral analysis, defective flip-chip interconnects that have not been revealed by standard acoustical imaging methods have been detected successfully. Acoustically found defects have been confirmed by subsequent FIB-cross sectioning and SEM imaging. The high resolution SEM imaging revealed complete and partial delamination at the interface between the die and the bump

An Overview of Non-Destructive Testing Methods for Integrated Circuit Packaging Inspection

“…The resolution of microscopic image depends on the acoustic frequency, the material properties and aperture of the transducer [ 51 ]. Figure 9 shows samples of different defects successfully detected by SAM.…”

A Survey of Detection Methods for Die Attachment and Wire Bonding Defects in Integrated Circuit Manufacturing

“…It is noted that recent SAM inspection approaches, e.g. [38][39][40][41][42][43][44], mainly focus on missing solder bumps/joints.…”

“…Image data acquired via x-ray often use image processing algorithms such as filtering, energy normalization, thresholding, and image enhancement for defect detection as discussed in [29][30][31][32][33][34][35][36][37]. In [38][39][40][41][42][43][44], images of flip chips captured by SAM systems were first segmented based on the flip chip structure using different segmentation techniques.…”

Experimental Studies of Conductive Paths of Printed Circuit Boards by Using Subminiature Eddy Current Transducers

“…Currently, complex and expensive laboratory test systems exist to identify specific failure modes through acoustic imaging and analysis. These systems utilize Scanning Acoustic Microscopy (SAM), Laser Doppler Vibrometry, or a combination of multi-spectral techniques to produce images of circuits and chips for failure mode and fault analysis [14][15][16][17][18][19]. Other techniques involve measuring the acoustic emissions from electronics while the system-under-test is undergoing mechanical stress [7].…”