1 / 17

kSA BandiT: Band-edge Thermometry

kSA BandiT: Band-edge Thermometry. Band-edge Thermometry Principles. Semiconductors: transparent for h ν < E g , opaque for h ν >= E g Semiconductors: as substrate temperature increases, E g ↓ and λ g ↑

jana
Download Presentation

kSA BandiT: Band-edge Thermometry

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. kSA BandiT: Band-edge Thermometry k-Space Associates, Inc.

  2. Band-edge Thermometry Principles • Semiconductors: transparent for hν < Eg, opaque for hν >= Eg • Semiconductors: as substrate temperature increases, Eg ↓ and λg ↑ • Look at diffusely scattered light component– not the specular component. Specularly reflected (front surface) light does not interact with the wafer. k-Space Associates, Inc.

  3. Band-edge Thermometry vs. Pyrometers • Pyrometers: • Typically inaccurate or no measurement below 400-450oC • Potential interference from stray IR (esp. at low Ts), internal reflections (heterojunctions), coated view ports • Absolute temperature calibration from machine to machine is difficult • Eg thermometers: • Need good light collection & detection system • Need good normalization & fitting software • Absorbing over layers limit thickness for temperature measurement k-Space Associates, Inc.

  4. kSA BandiT vs. Competitor Instruments • State-of-the-art solid state spectrometer - 1000x more sensitivity and no moving parts (longer lifetime, no need for constant recalibration) • Excellent S/N without a chopper • Efficient collection optics • Powerful software and full software development team • Operates in either transmission or reflection mode • Single USB connection to laptop computer • Full technical service and support k-Space Associates, Inc.

  5. kSA BandiT Product Specifications BandiT System Schematic k-Space Associates, Inc.

  6. kSA BandiT Product Specs. Cont’d BandiT Light Source • 150W halogen lamp with gold coated parabolic reflector. • Light source collimating optics. • Real-time output power control via BandiT software. • Internal feedback control for stable intensity and spectral output. • NOTE: above ~300oC can use heater as light source k-Space Associates, Inc.

  7. kSA BandiT Product Specs. Cont’d BandiT Detector • 2-inch collection optics focusing to 400 um fiber. • Single-axis gimble mount for radial scanning between inner/outer platen rings • Dual fiber with visible laser for easy alignment. k-Space Associates, Inc.

  8. kSA BandiT Product Specs. Cont’d • Spectrometer Visible Model (B-VIS): • 512x64 element Peltier-cooled CCD array detector • Wavelength Range: 380 nm – 1100 nm or custom • SiC, ZnTe, ZnSe substrates NIR Model (B-NIR): • 128 element InGaAs temperature stabilized photodiode array with on-board interpolation yields 1024 elements • Wavelength Range: 875 nm – 1400 nm • GaAs, Si, InP substrates k-Space Associates, Inc.

  9. kSA BandiT Software • Full hardware control and real-time feedback of lamp and spectrometer • Powerful, flexible fitting algorithms • Ability to store full, partial, or no spectra and temperature data • Full analog and digital I/O capability • USB interface, runs from a laptop k-Space Associates, Inc.

  10. Wavelength Ranges: 380-1100 nm1 875-1400 nm2 Temperature Update Rate: 20 Hz typical, 1 Hz minimum Typical Temperature Ranges: ZnSe: RT – 700 °C1 ZnTe: RT – 700 °C1 SiC: RT – 700 °C1 GaAs: RT - 690 °C2 InP: RT - 650 °C2 Si: RT – 600 °C2 Temperature Resolution: 0.1 °C Stability: +/- 0.2 °C (4 hours) Accuracy: +/- 2 °C Outputs: Real-time display Thermocouple (selectable) 10V analog (configurable) Inputs: Thermocouple, Analog kSA BandiT Performance Specifications k-Space Associates, Inc. [1] B-VIS model [2] B-NIR model

  11. BandiT Stability Data – GaAs @ 300C k-Space Associates, Inc.

  12. kSA BandiT Performance Specs (cont’d) • Noise from rotation ~1-2oC for all size wafers • Pyrometer noise typically much worse for ¼ X 3” pieces • No interference from: • hot sources • highly doped epi (2um of GaAs:C, p = 6.5e19/cm3) • high-on-low Eg growth (AlGaAs/GaAs) • Low-on-high Eggrowth: InGaAs/InP • InGaAs strong IR absorber • Clean measurement thru ~ 1.2 um of epi (using heater only) k-Space Associates, Inc.

  13. kSA BandiT Calibration File Generation • material • thickness • dopant level Calibration depends on: k-Space Associates, Inc.

  14. BandiT, TC, and Pyro Measurement GaAs Oxide Desorption Pyro reads high at low temps because substrate is transparent k-Space Associates, Inc.

  15. Interference Oscillations Oscillations in temperature k-Space Associates, Inc.

  16. Low Temp GaAs Growth TC does not see temp rise due to As Absorption Temp increase due to As absorption k-Space Associates, Inc.

  17. BandiT Measurement During Substrate RotationSpatially Resolved Wafer Temperature • Speed of solid state spectrometer provides spatially resolved temperature across all wafers • Wafer temperature can vary widely depending on thermal contact with holder • Temperature uniformity across each wafer depends on holder mechanism k-Space Associates, Inc.

More Related