Mitsukuni Tsukihara

Introduction of the SHX‐III System, a Single‐Wafer High‐Current Ion Implanter

The SHX‐III system, categorized as a single‐wafer high‐current ion implanter, has been developed by SEN Corporation in order to meet all the requirements for high dose and relatively high mid‐dose applications, including high‐tilted multi‐step implantation. Recently the three major advanced device types, namely logic devices, memory and imagers, started to require high‐current ion implanters in diverse ways. The SHX‐III is designed to fulfill such a variety of requirements in one system. The SHX‐III has the same end station as the MC3‐II/WR, SEN’s latest medium current implanter, which has a mechanical throughput of 450 WPH. This capability and precise dose control system of the SHX‐III causes dramatic productivity enhancement for application of mid‐high dose, ranged between 5E13 to 2E14 atoms/cm2, usually performed by medium current ion implanters. In this paper the concept and performance of the SHX‐III will be described, concerning influence of device characteristics. A concept and performance data of ...

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

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 eighteen-stage RF linear accelerator from the UHE, a multi-wafer ultra-high 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 systems - significantly 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.

Introduction of the MC3-II/GP system, medium current ion implanter with enhanced multi-charge beam current

The MC3-II/GP is a leading-edge single-wafer medium-current ion implanter, newly developed by SEN Corporation. It demonstrates exceptional productivity based on a high speed wafer-handling station and enhanced beam current. It covers a substantively wider energy range in order to fully meet advanced device requirements. Retaining the superior features of the MC3-II/WR, the MC3-II/GP provides a remarkable increase of multiply-charged beam current coupled with longer ion source lifetime. Another advanced feature of the MC3-II/GP is a 30 second or 14% reduction in auto beam setup time. These improvements enable a fabrication line to reduce the total number of ion implanters and dramatically reduce COO.

Precise beam angle control in the S-UHE, SEN's single-wafer ultra-high energy ion implanter

In order to fabricate highly sensitive image sensors (IS), ultra-high energetic ion beams such as 5MeV of boron are required. In order to address the requirement as well as more aggressive requirements of leading-edge IS, SEN has developed the S-UHE, an ultra-high energy single-wafer ion implanter. One of the most important features in the S-UHE is a precise beam angle control system to obtain stable implant depth of ion species against angle-sensitive channeling effects. It is very important for the precise control both to design a sophisticated beam line and to measure beam angles accurately. In this report, measuring techniques of the beam angle and the results are presented.

Profile and Angle Measurement System of SHX

To cope with the manufacturing processes for shrunk semiconductor devices, a precise implant angle control is required for the latest generation of ion implanters. Various ideas are incorporated into the SHX, a single wafer type high current ion implanter developed by SEN Corporation, to meet the requirements not only with a newly designed beam line but also with an accurate angle monitoring system.In the SHX, an ion beam is transported to the electrostatic beam scanning system after a mass analysis. The scanned beam passes through Parallel Lens to be arranged in the parallel direction. Next, the beam is bent vertically by the energy filter and reaches the wafer platen, finally. The beam profile measurement system, Beam Profiler, is positioned on the same plane as the wafer.The Beam Profiler can measure horizontal uniformity of the scanned beam current. Using the Divergence Mask, information about the horizontal beam parallelism at the wafer position also can be acquired. In addition, 2‐dimensional profil...

Symmetric beam line technique for a single-wafer ultra-high energy ion implanter

In order to fabricate highly sensitive image sensors, ultra-high energy ion beams, such as 5 MeV of boron, are required. SEN has developed the S-UHE, a single-wafer ultra-high energy ion implanter, to obtain such ultra-high energy beams. The S-UHE has adopted an electrostatic and symmetric, parallelizing lens system, the concept of which is already used in the MC3-II, a medium-current ion implanter, and the SHX, a single-wafer high-current implanter. This system provides very good uniformity, even when a large amount of outgassing from photoresist materials is generated. Since the ion beam energy is so high at the lens system, a compound electrostatic parallelizing lens system is introduced. Beam angles have been controlled within 0.05° for any recipe in experiments with the electrostatic parallelizing lens system. Another beam line element specifically adopted in the S-UHE is an electric quadrupole lens installed between the two dipole magnets, in order to suppress beam current loss. This electric lens can easily form achromatic ion beam transportation without any significant deformation of the magnetic field.

Productivity Improvement for the SHX—SEN’s Single‐Wafer High‐Current Ion Implanter

Equipment productivity is a critical issue for device fabrication. For ion implantation, productivity is determined both by ion current at the wafer and by utilization efficiency of the ion beam. Such improvements not only result in higher fabrication efficiency but also reduce consumption of both electrical power and process gases. For high‐current ion implanters, reduction of implant area is a key factor to increase efficiency. SEN has developed the SAVING system (Scanning Area Variation Implantation with Narrower Geometrical pattern) to address this opportunity. In this paper, three variations of the SAVING system are introduced along with discussion of their effects on fab productivity.

Dose control accuracy in pressure compensation

NV-GSD series ion implanters utilize pressure compensation systems to suppress dose shifts resulting from charge exchange between the ions and residual gas in the beam line such as from plasma shower systems or photoresist outgassing. Here we report on the following improvements in the pressure compensation system, which increase both its accuracy and availability : (i) a consideration of charge exchange in the analyzer magnet region, referred to as the beam line effect (ii) tabulation of pressure compensation factors to aid the automation of the pressure compensation system, and (iii) adoption of a new type of ion gauge which shows less variation between individual units as well as more stable behavior over time. As a result, the deviation in sheet resistance of implanted photoresist-containing wafers from implanted bare wafers is reduced to less than 1% (1/spl sigma/). The improved pressure compensation system described here is currently available on the NV-GSDIII series high current implanters.

SAion - SEN's unique solution for 450mm ion implant

The SAion-450 is a leading-edge ion implanter developed for the upcoming 450mm wafer generation. The SAion-450 has extremely wide process coverage and productivity throughout both the medium current (MC) and high current (HC) process ranges. Although the area of a 450mm wafer is 2.25 times larger than that of a 300mm wafer, the SAion-450 can process typical MC recipes with higher productivity than the current 300mm MC implanter, the MC3-II/GP. Additionally, low energy (LE) productivity can be significantly enhanced with the addition of the LE beam line option. This can be easily installed (or removed) in a production fab. The SAion product line also includes a 300mm model. The SAion-300 is equipped with the same beamline as the SAion-450 in order to deliver the same process characteristics in 300mm fabs as in 450mm wafer lines. Thus, the SAion series can serve as a bridge tool to assure smooth wafer size transition from 300mm to 450mm.

MILD system: Maskless implantation for local doping

SEN Corporation has developed a very flexible dose pattern modulation system called “MIND+”. This system can be used for yield enhancement by compensating for variation induced by other processes. In this paper, another important feature of SEN’s single-wafer implanters is introduced. The system is called the “MILD” system, standing for “Maskless Implantation for Local Doping.” MILD provides the capability to implant dopants at any positions on a wafer without hard masks or photo-resist patterns. In this paper, MILD system operation and results will be described.