Joseph C. Olson

Beam angle control on the VIISta 80 ion implanter

Advanced integrated circuit design requires precise control of beam incidence angle. This requirement has led to the development of an automated angle control system on Varian Semiconductors high current VIISta 80 ion implanter. In this paper we show beam incidence angle and angular spread measurements for 200 and 300 mm ion beams on the VIISta 80 ion implanter. Multiple beam measurements are sampled across the wafer plane for each beam setup. Beam angle computation results are compensated for prior to wafer implantation for optimal incident angle control. Beam, bare wafer and device performance data were used to confirm the accuracy of this measurement and control system. Excellent measurement accuracy and repeatability has been demonstrated. Data will be shown which includes arsenic, boron and phosphorus implants from both drift and decel operation. Benefits and process differences will be shown with active beam angle correction as compared to classical open loop methods. Mechanical tilt angle accuracy, repeatability and verification data will also be discussed.

Metrology Requirements For Single Wafer Ion Implanters

As production CMOS devices shrink to 90nm and below, the requirements for high quality ion beams increase in medium and high current implant systems. Critical variations in device performance can be related to changes in ion beam properties, such as ion beam size, shape and density as well as ion beam angle steering and distribution. Transistor properties are known to be sensitive not just to mean beam angle but also to details of the distribution of angles contained within the beam. As a result, modem single wafer implanters are required to monitor more than just the energy and dose of implanted ions. The process security provided by single wafer ion implantation can be ensured by measurements which verify the angle integrity of each setup and implant. Monitoring of energy contamination, another element of beam quality, allows end users to utilize the improved productivity of decel operation on high current implanters while maintaining minimal and, more importantly, repeatable energy contamination. Final...

Angle Effects in High Current Ion Implantation

Previous studies conducted on batch high current implanters with 130 nm devices[1] have shown the importance of implant angle during source‐drain (SD) and source‐drain extension (SDE) implants. For these implants, errors in implant angle lead to device asymmetry and this device asymmetry has been cited as a reason for requiring single wafer high current implanters[2]. The sensitivity of device performance to angle is increasing as devices shrink. For current anneal technologies, angle effects are more importance in NMOS, due to the lower diffusion of arsenic. However, the importance of implant angle in PMOS is expected to increase as diffusionless anneals are adopted. In this paper we report on angle effects in single wafer high current ion implantation, for the improvement of the characteristics of MOSFETs integrated into Systems‐on‐a‐Chip (SoCs) of 65 nm or beyond. The single wafer high current implanter and its angle measurement and control system will be described. A comparison of the implanter’s angl...

Next Generation Medium Current Product: VIISta 900XPT

Device fabrication requirements for 32 nm and 28 nm technologies further increase the demands on medium current implanters for higher process quality as well as for increased productivity and flexibility. Angle control requirements continue to become more stringent with scaling of device geometries. Pressure for reduced CoO drives the need for higher productivity and this, in turn, drives requirements for tuning time with precise angle control that are substantially more aggressive than for older generation tools. Additionally, dose control and defect control standards have become more demanding. We discuss these requirements in more detail and describe the improvements that have been made to Varian’s next generation medium current tool in order to meet them.

High-Uniformity Inductively Coupled Plasma Source With Magnetic Multicusp Confinement

A high-uniformity inductively coupled plasma source is presented. The plasma uniformity is improved with a magnetic multicusp structure that surrounds the plasma chamber. A picture showing the alternating bright and dark plasma regions along the perimeter of the plasma chamber-an effect of the magnetic confinement-is presented as well.

Next Generation Angle Control for Medium Current and High Energy Implanters

Angle control continues to increase in importance with device scaling. For instance, threshold voltage and on‐state current in advanced logic devices depend critically on the angle accuracy of medium current halo implants. TCAD simulation results, showing that on‐state current changes of greater than 1% per degree of implant angle are possible, are presented. We report here on improvements to angle performance and control in both the horizontal and vertical directions. Beam data covering the full operating space of the VIISta 900XP is presented, demonstrating total angle control of better than ±0.2°. The data set is chosen to emphasize performance of typical halo implants. Single wafer high energy angle control data is also presented.

Optimized Autotuning for Single Wafer High‐Current and Medium‐Current Implanters

As semiconductor lot sizes decrease the impact of autotuning performance on productivity is increased. The dual magnet architecture of the VIISta series of single wafer ion implanters provides unparalleled defect prevention and beam control while presenting unique challenges for autotuning. We present data from field installations of high‐current and medium‐current VIISta implanters demonstrating excellent autotuning performance in terms of tuning speed and success rate.

Varian semiconductor indirectly heated cathode sources

Indirectly heated cathode ion sources have been developed for the VIISta 3000 and 810HP series ion implanters. The sources greatly increase lifetime and maintain or improve beam current output for all species and charge states. The sources are designed with common consumables. Source lifetime, beam current, stability, and tuning data are presented.