Process technology and analytical equipment at the MBE

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Layering and process technology for device manufacturing

• S1000 MBE system by DCA instruments
  © DCA Instruments 2003

  The DCA Instruments S1000 MBE system comprises six separate vacuum chambers and has the capacity to accommodate wafers up to 200 mm in diameter. The growth chamber in this system enables the utilization of group IV materials (such as Si, Ge, C), rare earth oxides Gd₂O₃, Nd₂O₃), and boron for epitaxial layer growth. The growth process of these layers can be precisely monitored in situ using reflection high-energy electron diffraction (RHEED). Additionally, the system allows for in situ analysis using photoelectron spectroscopy (as described below) and in situ metallization of the sample's front surface.

• Centrotherm E2000 Horizontal Furnace
  © MBE 2020

  The Centrotherm horizontal furnace system E2000, has a total of 4 floors or tubes. This configuration allows independent thermal oxidation (wet/dry), LPCVD (SiNX, Poly-Si), LTO (TEOS/Silane) and PECVD (SiNx) processes. The system is located in the clean room of the LNQE.

• Ion implanter ViiSta HCS by Varian
  © MBE 2020

  The ion implanter is a fully-fledged production tool of the semiconductor industry. Its high current system can accelerate ions with up to 60 keV (up to 180 keV triple charged). The handling system is designed for modern wafer sizes of 300 mm diameter. A total of 4 implantation species are available: Ar, AsH₃, BF₃ und PH₃. The system is located in the clean room of the LNQE.

• Rapid heating furnaces (rapid thermal processing - RTP)
  © MBE 2020

  There are four available systems for conducting rapid curing processes, each applicable depending on the specific use (metal, RTO, FGA, implant activation, etc.). These systems can perform processes at temperatures of up to 1100 °C under various atmospheres (Ar, H₂ + N₂, N).

• Additional equipment
  • Sputtering and electron beam evaporation systems (in the clean room of the LNQE)
  • Reactive ion etching (in the clean room of the LNQE)
  • Photolithography (in the clean room of the LNQE)

Structural analytics

• Bruker D8 Discover x-ray diffractometer
  © MBE 2020

  The Bruker D8 Discover II X-ray diffractometer (XRD) enables the structural analysis of epitaxial layers. This XRD system employs a copper anode, and the radiation is confined to the Kalpha1-line through a monochromator. However, in the grazing incidence X-ray diffraction (GIXRD) configuration, the monochromator can't be used, resulting in the presence of the Kalpha2-line. To minimize Kbeta radiation, a Göbel mirror is utilized, filtering it almost completely. This system allows for various analyses, including reciprocal space maps (RSM), theta-2theta, omega-2theta scans, and rocking curves. Additionally, reflections in skew geometry can be investigated using the Euler cradle.

• Atomic force microscope
  © MBE 2020

  The Park Scientific atomic force microscope allows a maximum measurement range of 100 µm x 100 µm and offers a height resolution under one Ångström. Depending on the application, both contact and intermittent contact modes are available for use.

• Renishaw inVia Raman Spectroscope
  © MBE 2020

  Raman spectroscopy is a non-invasive technique used for examining the vibrational and bonding characteristics of samples. It operates based on the principle of inelastic scattering of photons by the sample. This method allows for the measurement of factors such as strains, layer compositions, and occasionally, thicknesses, rarely dopants within the sample.

  We have two excitation sources at our disposal: a HeNe laser (632.8 nm) and a diode laser (785 nm). The gratings available enable us to achieve a resolution of approximately 0.9 cm^-1. In addition to conventional single Raman spectrum recordings, we can perform sample mapping with step sizes as small as 100 nm or larger, producing a heat map that visualizes local strains within the sample.

• Photoemission Spektroscopy UPS/XPS
  © MBE 2020

  Photoelectron spectroscopy (XPS) can be performed within the analysis chamber, eliminating the need to remove the sample from the vacuum environment. The XPS system is equipped with a Thermo VG Scientific XR3E2 source, featuring an aluminum-magnesium double anode, and a SPECS UVS 10/35 UPS source that can generate He-I and He-II radiation. For detection, a Specs  Phoibos 100 hemisphere analyzer with a fivefold channeltron is employed. To determine the work function of the sample, it is possible to apply an underlay voltage to the sample. Furthermore, the angle of the sample surface in relation to the detector can be adjusted, enabling angle-resolved XPS (ARXPS) measurements.

• Additional Analytics Available
  • Scanning electron microscope
  • Transmission microscopy (use of the TEM at LNQE)
  • Spectral ellipsometry

Measurement Technologies

• Measurement of Capacitance-Voltage Characteristics
  © MBE 2020

  Capacitance-voltage measurements can be performed for wafer sizes up to 150 mm. Both quasi-static and high-frequency measurements in the frequency range from 100 Hz to 1 MHz are possible. Additionally, the sample temperature can be varied between 21 °C and 100 °C.

• Current-Voltage Characteristics Measurements
  © MBE 2020

  Current-voltage measurements can be performed for wafer sizes up to 100 mm. Up to 4 measuring probes are available for contacting. In addition, the sample temperature can be varied between 21 °C and 150 °C.

• Karl-Süss-Proberstation incl. Keithley 4200 Parameter Analyzer
  © MBE 2020

  In addition to simple capacitance and current-voltage measurements, this measuring station allows for semi-automated analysis at wafer level. With up to 4 contacts, the input and output characteristics of bipolar and MOS transistors can be analyzed directly. The sample temperature can be varied between 21 °C and 150 °C.

• Sinton Instruments WCT-120 Quasi-Static Photoconductivity Measurements
  © MBE 2020

  This device enables characterization of charge carrier lifetimes of silicon substrates for photovoltaic applications.

• Transient Current-Voltage Analysis of Solar Cells
  © MBE 2020

  This custom-built measurement setup serves the purpose of conducting transient analysis of exceptionally efficient solar cells. It incorporates an array of LEDs positioned above the solar cells, enabling pulsed operation of the cells. When coupled with an oscilloscope, this setup facilitates the characterization of the solar cells' performance during switch-on, switch-off, and transition phases.

• Additional Measurement Technologies
  • Temperature-dependent CV and IV measurements in the temperature range from 77 K to 400 K

Numerical Process and Device Simulation

• Process Simulation
  © J. Krügener 2020

  The MBE employs the company Synopsys's Sentaurus Process software for conducting numerical simulations of semiconductor technology processes.

• Devices Simulation
  The MBE employs the company Synopsys's Sentaurus Device software for conducting simulations of device characteristics.