X-rays in Semiconductor

Sigray’s x-ray solutions include 3D x-ray microscopes and microXRF systems in vacuum environments. These systems are used for a range of semiconductor applications, including everything from inspection of wafer contamination and silicon-side process monitoring to failure analysis of packaging.

Packaging Failure Analysis at Highest Resolution

The ever-shrinking dimensions of advanced packaging necessitates ultrahigh resolution in large, intact packages. Sigray produces two systems: Apex XCT-150 (ultrahigh throughput) and EclipseXRM-900 (ultrahigh resolution) for semiconductor needs in failure analysis.

Both represent a step change from existing 3D x-ray microscopes (XRMs) which have become a workhorse for semiconductor FA, but have been limited by their reliance on two-stage magnification geometries that necessitate the use of inefficient, ultrathin scintillators.

EclipseXRM provides ultrahigh resolution imaging of advanced packages, such as <10 um microbumps and hybrid bonds.
Wire bond regions of interest in a commercial SD card, imaged at 0.15 micron voxel (0.3 micron spatial resolution). Cropped region of interest (wire bond pad) from this image is below, showing a 0.9 micron void/crack.
X-rays for Circuit Debugging (X-ray Assisted Device Alteration)

Backside power delivery (BPD) is widely anticipated by the semiconductor industry to be a pivotal development, enabling more efficient power delivery due to reduced resistance and significant improvements to transistor density (20-30% cell area reduction). The challenge with BPD is that existing circuit debugging / marginal fault isolation techniques such as LADA (laser assisted device alteration) will become obsolete.

Sigray has developed a new technique called X-ray Assisted Device Alteration (XADA). The Sigray XADA-200 provides microns-scale probing of intact devices under test (DUT) to isolate critical speed paths. Its introduction won the Outstanding Paper of the Year at ISTFA 2022, co-published with Dr. William Lo at NVIDIA.

3-4 ps delay seen using Sigray XADA
Reverse Engineering & Trusted Circuit

Sigray’s Apex XCT-150 provides 0.5 um resolution 3D imaging of large PCBs and packages within minutes for reverse engineering and trusted circuit applications. Complete montages of intact packages of 200 cm x 200 cm are possible at spatial resolutions down to 0.5 um.

Download Applications Note on PCB Imaging with Apex Download Applications Note on LFOV (Mosaic) with Apex
Wafer Level Packaging

Apex XCT-150 enables intact wafer imaging for next-generation packaging schemes. The system is successfully used for submicron failures such as voids, non-wets, cracks, etc. in TSVs, hybrid microbumps, and solder.

Voids clearly rendered in 5 um TSVs within minutes. Imaged within an intact 300mm wafer on the Apex XCT.
Front-end-of-the-line (FEOL) Process Monitoring

Sigray’s AttoMap XRF has been adopted by leading semiconductor companies for inspection of FEOL processes due to its accurate quantification and small spot sizes of 3-20 µm, allowing focusing of the beam completely within a 40 µm test pattern. The high sensitivity of the AttoMap enables quantitative analysis of trace levels of dopants and has demonstrated down to sub-Angstrom equivalent thickness.

Laddered sample performed on AttoMap-200 showing high degree of linearity and sensitivity down to 0.03 Angstroms of equivalent thickness for Co
Organic Contaminants and Trace Low-Z Elements

There is a general misperception that quantification of low atomic number (Z) elements such as B, C, O, and N at minor to trace levels is not achievable with microXRF at high resolutions. AttoMap-310 features a high vacuum chamber and a patented Si-based x-ray source that provides optimal illumination for low atomic number elements. Information on B doping and organic contamination can be achieved at excellent resolution (10-100 µm).