Implantation and metrology solutions for low energy boron implant on 450mm wafers

Abstract

The transition to semiconductor manufacturing on 450mm wafers continues to be one of the biggest challenges in the semiconductors industry. Even though lithography is critical for 450mm development, process tools such as ion implantation and associated metrology are also challenged by scaling-up to keep acceptable CoO and excellent capabilities. There is a double challenge: scale up to 450mm and cope with shallower or 3D doping specifications. For beam line implanters, the 450mm is challenging: direct beam imposes a process time linear with the implanted area and a throughput which decreases while reducing energy. Therefore the 450mm is a great challenge. Plasma immersion ion implantation (PIII) technology offers a good alternative to beam line implanter with a high throughput at low energy, an implant time independent from the surface area and the possibility to implant on 3D structures. IBS has built a 450 mm PIII prototype based on its PULSION® Technology [1] and is evaluating non uniformity of BF3 implantation on 450 mm n-type wafers. To monitor such a light element we used the Shallow Probe tool, based on a simple, original and unique approach: Low Energy Electron induced X-ray Emission Spectroscopy (LEXES). The wafer is probed by a low energy electron beam and the soft X-rays emission is collected in WDS (Wavelength Dispersive Spectroscopy) spectrometers. The technology uses a dedicated low energy and high current electron column that has been specifically designed by CAMECA to optimize surface analysis instead of bulk analysis [2]. CAMECA is developing a new 450mm tool and collaborates with IBS to provide solutions to semiconductor manufacturers for ion implantation. LEXES results of B dose implant mapping have demonstrated a B dose non-uniformity of less than 4% over a 450mm wafer. Additionally the LEXES tool has been used to assess uniformity of the in-depth localization of the boron implant.