Shu Satoh

Optima XE Single Wafer High Energy Ion Implanter

The Optima XE is the first production worthy single wafer high energy implanter. The new system combines a state‐of‐art single wafer endstation capable of throughputs in excess of 400 wafers/hour with a production‐proven RF linear accelerator technology. Axcelis has been evolving and refining RF Linac technology since the introduction of the NV1000 in 1986. The Optima XE provides production worthy beam currents up to energies of 1.2 MeV for P+, 2.9 MeV for P++, and 1.5 MeV for B+. Energies as low as 10 keV and tilt angles as high as 45 degrees are also available., allowing the implanter to be used for a wide variety of traditional medium current implants to ensure high equipment utilization. The single wafer endstation provides precise implant angle control across wafer and wafer to wafer. In addition, Optima XE’s unique dose control system allows compensation of photoresist outgassing effects without relying on traditional pressure‐based methods. We describe the specific features, angle control and dosim...

Beam energy tracking system on Optima XEx high energy ion implanter

The Axcelis Optima XEx high energy implanter is an RF linac-based implanter with 12 RF resonators for beam acceleration. Even though each acceleration field is an alternating, sinusoidal RF field, the well known phase-focusing principle produces a beam with a sharp quasi-monoenergetic energy spectrum. A magnetic energy filter after the linac further attenuates the low energy continuum in the energy spectrum often associated with RF acceleration. The final beam energy is a function of the phase and amplitude of the 12 resonators in the linac. When tuning a beam, the magnetic energy filter is set to the desired energy, and each linac parameter is tuned to maximize the transmission through the filter. Once a beam is set up, all the parameters are stored in a recipe, which can be easily tuned and has proven to be quite repeatable. The magnetic field setting of the energy filter selects the beam energy from the RF Linac accelerator, and in-situ verification of beam energy in addition to the magnetic energy fil...

Productivity improvements utilizing OptiScan, interlaced beam scanning, for Axcelis Purion XE implanter

The Axcelis Purion XE is a RF linac based single wafer, hybrid scan, high energy ion implanter. The Purion XE provides customers the highest mechanical throughput with best in class beam currents. It is also equipped with features to fully utilize its high beam current capability such as IntelliScan. IntelliScan maintains precise dose and uniformity even under conditions of extreme photoresist outgassing due to high beam power. To further enhance the Purion XEs industry leading productivity, OptiScan, a system for enhancing the beam utilization, has been developed.

IntelliScan, real-time scan waveform correction for dose uniformity on extreme photoresist implant conditions with optima XEx

To take full advantage of the high beam current capability of the Optima XEx on photoresist implants, a new, real-time uniformity correction scheme, IntelliScan, was developed. IntelliScan compensates for the dose asymmetry in beam-scan direction developed by charge exchange reactions due to severe photoresist outgassing. It continuously modifies the 1 KHz beam-scan waveform in real-time, according to instantaneous vacuum level in the angle corrector area. Since IntelliScan does not involve any extra steps in wafer handling, such as alternating 180° twist on every pass, high wafer throughput and implant angle integrity can be maintained throughout the entire implant process. This paper will describe the IntelliScan system and its performance on photoresist implants under extreme beam power conditions.

Dose Control System in the Optima XE Single Wafer High Energy Ion Implanter

Photoresist outgassing can significantly compromise accurate dosimetry of high energy implants. High energy implant even at a modest beam current produces high beam powers which create significantly worse outgassing than low and medium energy implants and the outgassing continues throughout the implant due to the low dose in typical high energy implant recipes. In the previous generation of high energy implanters, dose correction by monitoring of process chamber pressure during photoresist outgassing has been used. However, as applications diversify and requirements change, the need arises for a more versatile photoresist correction system to match the versatility of a single wafer high energy ion implanter. We have successfully developed a new dosimetry system for the Optima XE single wafer high energy ion implanter which does not require any form of compensation due to the implant conditions. This paper describes the principles and performance of this new dose system.

Beam Energy Purity on Axcelis XE High Energy Ion Implanter

The multi-stage RF acceleration in the Axcelis Purion XE high energy ion implanter has strong velocity filtering which allows only those ions with the correct flight time at the correct phase at each acceleration gap to get properly accelerated. On Purion XE, the energy spectrum exiting the RF linac is further purified with a magnetic momentum analyzer to remove any ions with the wrong energy or charge state before proceeding to electrostatic beam scanning and a magnetic parallelizing lens. A new on-tool EC detection method is introduced, which is based on the Energy Tracking System on Purion XE, to avoid the sole reliance on costly SIMS analysis for routine beam purity confirmations. We demonstrate the effectiveness of the new method and also demostrate the energy purity of Purion XE.

Damage engineering on Purion XE™ high energy ion implanter

Many IC and CIS manufacturers still rely heavily on batch high energy ion implanters such as the Axcelis HE3 and Paradigm XE systems. Angle control continues to become increasingly important with the scaling of devices and the increasing use of channeled implants to reduce the number of implant steps needed to produce a box-like dopant profile. The use of channeled implants limits the use of batch ion implanters for these applications due to the cone angle effect. The introduction of serial high energy ion implanters to replace the batch implanters has exposed subtle differences in damage characteristics related to the differences in tool architecture. Investigation into second order differences in the damage characteristics of the single wafer and batch implanters have resulted in the development of a new system for modifying the electrostatic scanning of the ion beam on the Purion XE with implications for improvement in damage reduction, low dose stability and utilization of the systems mechanical throughput limit.

Angle Control on the Optima HE/XE Ion Implanter

The Optima HE/XE is the latest generation of high energy ion implanter from Axcelis, combining proven RF linear accelerator technology with new single wafer processing. The architecture of the implanter is designed to provide a parallel beam at the wafer plane over the full range of implant energies and beam currents. One of the advantages of this system is the ability to control both the horizontal and vertical implant angles for each implant. Included in the design is the ability to perform in situ measurements of the horizontal and vertical angles of the beam in real time. The method of the horizontal and vertical angle measurements is described in this paper.