Semiconductor research, alongside other research, relies on small features for scientific study. In order to create these small features, optical lithography has been traditionally used as it ensures both sufficient quality and high throughput. However, optical lithography is resolution limited and new techniques are required to produce chip features smaller than 100 nm.
Extreme ultraviolet (EUV) lithography is able to produce these smaller features using a wavelength of 13.5 nm. It uses the same basic design tools; all while retaining the look and feel of the traditional optical lithography process. Therefore, it quickly became the method of choice.
As the features created by EUV lithography are so small, x-ray imaging is required to find any defects. Therefore, x-ray cameras are essential for quality control of EUV lithography surfaces.
Cameras for Imaging EUV Lithography Surfaces
Defects within EUV lithography produced semiconductors rely on x-ray diffraction to obtain high resolution. Any defects will diffract strongly causing intensity changes in the image.
The SOPHIA-XO features high quantum efficiency of >95% over the energy range 5 eV – 30 keV alongside large sensor formats for almost perfect image capture.
With low read noise, high frame rates and multiple port readouts the SOPHIA-XO offers high throughput imaging to show even the smallest of defects.
When imaging semiconductors for quality assurance it is important to remember that different imaging modalities are able to capture different defects. Therefore, different x-ray ranges can be employed to ensure capture of the majority of defects.
The PIXIS XO offers high resolution and sensitivity over the 30 eV – 20 keV range, for directly detecting soft x-rays.
The PIXIS XO comes with a wide selection of CCDs for ultimate experimental flexibility. The ultra-high-vacuum-seal design further enhances the flexibility of the PIXIS XO, with software-selectable gains and readout speeds.
Defect detection often requires high spatial resolution, as defects often occur at the edges of semiconductors. The PIXIS XF utilizes fiberoptic coupling to preserve the highest spatial resolution, imaging indirect x-rays less than 3 keV in energy.
The unique mechanical design allows for outstanding flexibility. Specialized, removable phosphor screens allow for optimization of the system, with the PIXIS XF coming with a choice of front- or back-illuminated CCDs for different experimental design.
The PI-MTE3 is able to offer in-vacuum detection of x-rays at high frame rates to ensure that no information is lost. This is paramount for high throughput defect detection.
With large format, deep-cooled CCDs, the PI-MTE is highly sensitive over the 10 eV – 30 keV range, offering direct detection of x-rays in this range.
Defect detection requires very high resolution and therefore requires low noise. The PI-MTE3 is liquid cooled, resulting in low dark current over long integration times.