This paper investigates the enhanced inspection of High Bandwidth Memory (HBM) stacks using Scanning Acoustic Microscopy (SAM). As the multi-layer structure is quite complex, sophisticated signal processing methods are employed. To improve detection capabilities and inspection time, the Synthetic Aperture Focusing Technique (SAFT) is utilized. In contrast to previous trials applying SAFT on SAM data, this contribution introduces Near Field SAFT. Reconstruction is also performed for layers between the transducer and its focus, in the near field of the transducer. This approach allows for measurements with common working distances, providing higher frequencies and improved resolution. Systematic evaluations are conducted on various measurement setups and transducers with different center frequencies and focal lengths in order to determine the most optimal measurement setup.

Recently, a new approach for isolation of open faults in integrated circuits (ICs) was developed. It is based on mapping the radio-frequency (RF) magnetic field produced by the defective part fed with RF probing current, giving the name to Space Domain Reflectometry (SDR). SDR is a non-contact and nondestructive technique to localize open defects in package substrates, interconnections and semiconductor devices. It provides 2D failure isolation capability with defect localization resolution down to 50 microns. It is also capable of scanning long traces in Si. This paper describes the principles of the SDR and its application for the localization of open and high resistance defects. It then discusses some analysis methods for application optimization, and gives examples of test samples as well as case studies from actual failures.

The 3D package configuration presents challenges to conventional Fault Isolation (FI) and Failure Analysis (FA) methods. This paper illustrates that with correct Electro Optical Terahertz Pulse Reflectometry (EOTPR) data processing, interpretation and additional reference spectra, the combination of EOTPR to isolate the open/high resistance failure location and 3D X-ray Computed Tomography (CT) to image the failure is very effective for System in a Package (SIP) FI/FA.

The development of a next generation high-resolution x-ray Computed Tomography (CT) tool and its applications are reported in this paper. Some of the key features are region of interest capability, improved time-to-data, improved usability, and data collection automation capability. We also discuss the key technical challenges that are faced by x-ray CT technology. Critical cases that are hard or not possible to isolate by alternative methods are also discussed. Examples include Controlled Collapse Chip Connection (C4) bump cracking and “invisible” non-wetting analysis, ball grid array (BGA) solder joint cracking, and wirebond microcracking and wirebond shorting, as well as demonstration of progressive testing capability.

New package technologies are getting more complex, and thus isolating defects is becoming more challenging [1]. Analytical tools like Scanning SQUID Microscopes (SSM) are thus gaining relevance based on the capability to non-destructively detect electrical fails in very complex package technologies [2]. In this paper we report the use of SSM for the nondestructive isolation of electrical fails in novel microelectronic packages, where SSM has been found to be a unique fault isolation technique.