E-Beam Boron Doping Source EBVV-B

Up to 10²¹ /ccm Boron doping in Si-MBE
Evaporation of elemental Boron or Si-B alloy in vertical e-beam evaporator
Small dimensions; can be used in DN63CF (O.D. 4.5“) effusion cell ports; hearth volume 5 cm³
Long filament lifetime and easy maintenance
270° beam deflection
High frequency x-y-beam deflection system
Silicon shielding parts for use in SiGe-MBE Datasheet

Introduction

The Vertical Electron Beam Evaporator EBVV-B 63-5 allows to introduce real e-beam evaporation into your MBE system that has originally been designed for effusion cells only.

The unique and extremely compact design permits to install the EBVV-B 63 instead of an ordinary effusion cell on any MBE system having CF63 ports with an I.D. ≥ 60 mm. Even tilted ports can be used. Despite its small footprint, the new EBVV-B 63 includes a complete electromagnetic x- and y-dynamic beam deflection system and can deliver beam powers up to 3 kW.

The evaporator hearth volume is 5 cm³.

The 270° beam deflection design of the electron emitter eliminates nearly all ion bombardment on the filament due to a sharply bent electron beam path near the beam exit aperture. Thus, the filament is well shielded from evaporant or charged particles ejected from the crucible.

EBVV 63-4 close-up view — EBVV-B 63-4 , view onto emitter block and filament

Application

The EBVV-B 63-5 allows high purity evaporation of elemental boron or Si-B alloy. Consequently, it allows Si and SiGe MBE growth of highest Boron doped epi-layers with Boron concentrations up to 1021/ccm.

This concept is applied in Si/SiGe HBTs or Si based Esaki-Diodes with record peak-to valley ratio and current density. The SIMS profile below shows a 275 nm Si layer with high Boron doping.

**EBVV-B 63-5,** pool of molten silicon (EBVV is mounted into a port 35° to the vertical axis)

Silicon shielding parts

The EBVV-B is equipped with a specially adapted set of shielding parts manufactured from high-purity single crystalline Si. A Si plate and a ring cover all parts of the metallic body that are potentially subject to electron or ion bombardment and that face the substrate.

Only this Si-shielding allows the growth of highest purity Boron doped Si and SiGe films.

We also supply high purity Si-B source material in superior quality. It is machined and pre-conditioned from wafer-grade Si-single crystals and high purity Boron, fitting the evaporator hearth.

Set of silicon shielding parts for **EBVV-B 63-5**

Technical Data

Mounting flange	DN63 CF (O.D.4,5“) or DN100 CF (O.D.6“)
Dimensions in UHV	Length: 234 – 450 mm (user specific); ØD: 60 mm
Crucible capacity	5 cm³
Hearth dimensions	Ø 23 mm (12° taper) x 15 mm
Filament type	short-legged coil of W wire, electron emitting filament
Bakeout temperature	200° (all air side connectors removed)
Operating pressure	1 × 10^-11 mbar ….1 × 10^-5 mbar
Accelaration voltage	4 - 6 kV
Beam power	max. 3 kW
Filament current	max. 25 A at 10V (AC)
Spot size	5 mm diameter, approx.
Primary beam deflection	C270° by permanent magnet system
Dynamic beam deflection	coils wound from KAPTONTM isolated wire; defl. frequency: max. 150 Hz; x-deflection current: ± 1,5 A max.; y-deflection current: ± 2 A max.
Water cooling	Min. water flow rate 5 l/min at 4 bar
Options	Tilted hearth (T); integrated rotary shutter (S)

Dimensions

Schematic drawing EBVV-B — Schematic drawing of the Electron Beam Boron Doping Source EBVV-B (drawing shows EBVV-B 63-5)