VIISta® 900 3D
The Varian VIISta 900 3D system succeeds the Varian VIISta 900 XPT as the industry’s flagship medium-current ion implanter for high-volume manufacturing. The new system addresses escalating requirements for implant (or doping) precision and the demand for zero-defect performance in fabricating emerging 3D device architectures beyond the 2xnm node. Its beam line architecture has been specially designed with the angle accuracy and beam shape control necessary for exact dopant placement and minimal within-wafer and wafer-to-wafer variability for a variety of applications in logic FinFETs and 3D memory structures. In addition, these capabilities benefit CMOS image sensor technology as well as the most advanced planar structures.
The new system leverages the proven world-class particle performance of the VIISta platform beam line architecture. A filter magnet removes the majority of unwanted implant species right at the source. Triple-magnet architecture delivers the cleanest beam line available among medium-current systems, removing beam-borne metals, particles, cross-species, and contamination well before the beam reaches the wafer. A unique combination of vertical angle and beam shape controls improve implant precision, and closed-loop micro and macro uniformity metrology that minimize implant variability. Repeatable and accurate implant angle control is a critical parameter for advanced devices in which the slightest variation can severely affect yield. These controls tighten vertical and horizontal angle accuracy to 0.1º, a two-fold improvement over previous-generation technology.
Controlling crystalline damage is critical to the performance and power consumption of 3D devices. Two features of the VIISta 900 3D system minimize such damage. First, integrated hot-implant capability maintains the crystallinity of silicon and high-mobility channel materials during ion implant. Implants at elevated temperatures eliminate corner and growth defects in 3D structures, increase dopant activation, and reduce defect-induced device leakage. Secondly, controlled beam density modulation (dose rate control) allows the user to further reduce crystalline damage for a given recipe condition.
Enhanced beam shape and dose control make possible newly optimized SuperScan™ capabilities. This feature improves device performance and yield by correcting non-uniformities introduced by upstream process steps other than implantation. New SuperScan 3 algorithms enable custom dose delivery for virtually any desired pattern without having to rotate the wafer. The system accommodates up to seven different zones with a zone dose ratio as high as 7:1 while maintaining excellent dose accuracy and uniformity within the different zones.