EUV Technologies and Capabilities

MoSi performance benchmarks

In order for EUV multilayers to be of practical use, they must have ultra-low roughness on the nanometer scale, measurable only with the use of an atomic force microscope (AFM). A typical Molybdenum-Silicon (MoSi) multilayer will contain 80 individual thin layers of 2.5 nm – 4 nm thickness, where the roughness of each interface must be less than 0.2 nm. Putting this in perspective, the radius of an individual Mo atom is 0.14 nm!

Rigaku repeatedly demonstrates capability to produce world-class EUV multilayer performance. Some of our achievements and benchmarks are shown below.

Champion MoSi multilayer

With the use of optimized interfacial-stabilization layers, the champion performance for Rigaku with MoSi is 69.2% peak reflectivity for normal incidence. Compared to Rigaku’s routine performance of 66.5% for 40-layer ML and 67.5% for 60-period ML, this champion performance would produce up to +60% more total power in a 12-optic lithography system.

High-temperature Mo/X/Si multilayers

With the use of interface-stabilization layers optimized for temperature stability, Rigaku produces EUV multilayers with excellent temperature stability, capable of retaining high reflectivity and minimal peak shift when subjected to vacuum annealing at high temperatures.

EUV High-Selectivity Multilayers

In addition to standard MoSi multilayers with ~4% bandpass, Rigaku developed multilayers for specialized applications requiring high-selectivity. The multilayer below narrows the bandpass to 1.1% using SiC and Si layers.