Introduction of the S-UHE, a single-wafer ultra-high energy ion implanter

Abstract

In order to address the process requirements of leading-edge image sensors, a new single-wafer ultra-high energy ion implanter, the S-UHE, has been developed. This product incorporates two exceptional subassemblies. One is the eighteenstage RF linear accelerator from the UHE, a multi-wafer ultrahigh energy implanter, offering maximum beam energy of 2MeV per charge. The other is the field proven end station used by the MC3-II/GP, a single-wafer medium current implanter, which can provide throughput of over 450 wafers/hour. The S-UHE has a unique beam line concept where beam energy analyzing magnets bend the accelerated beam 180°. This system minimizes tool footprint, providing additional space for maintenance. Other key elements of the beam line include an electrostatic scanner, parallelizing lens and energy filter. The electrostatic scanner provides higher scan speed than mechanical systemssignificantly improving dose uniformity compared to a batch high energy implanter.Additionally, the S-UHE ensures accurate implant angles and ultra-low level of metal contamination, both of which are very important parameters for advanced image sensors.

A Review of Ion Implantation Technology for Image Sensors †

“…Lastly, discussion is focused on zero-degree tilt implantation, which is applied to avoid shadowing occurring due to resist patterns and to obtain deeper profiles by intentional channeling. Figure 19 shows the SIMS profiles implanted with 0.4–0.8° tilts in 0.1° steps, 1.5 MeV energy, 1 × 10 13 cm −2 dose of B + [ 31 ]. There are clear differences in the SIMS profile even only 0.1° tilt steps due to the channeling differences.…”

“… Secondary ion mass spectroscopy (SIMS) profiles implanted in 0.1° tilt steps [ 31 ]. Ion: B + ; Energy: 1.5 MeV; Dose: 1 × 10 13 cm −2 ; Tilt: 0.4–0.8°.…”

Sheet resistance measurement for ultra-high energy ion implantation

“…The light sensitivity of advanced image sensors can be improved with deep photodiode structures, which require high energy ion implantation. To meet these energy requirements, Sumitomo Heavy Industries Ion Technology (SMIT) has released single-wafer ultra-high-energy implanters, such as S-UHE [1] and SS-UHE [2], which can realize 3-µm or higher implantation depths. Although these tools enable deeper implantation, the conditions near the wafer surface may differ from those in shallow implantation.…”