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.
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.

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).