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Center of MicroNanoTechnology CMi

Rapid Thermal Processing Jetfirst 200


Contents: CMI

  1. Introduction
  2. Equipment description
  3. Authorized and not authorized samples and treatments
  4. Process description
  5. Process window and standard preheating curve
  6. Abort routine
  7. Temperature setting / controlling / monitoring
  8. Loading and unloading samples
  9. Thermocouple positioning and thermocouple withdrawal
  10. How to use the system

I. Introduction CMI

The JetFirst 200 system is a bench top RTP (Rapid Thermal Process) tool. It is dedicated to the following applications or processes:

  • RTA: Rapid Thermal Annealing for silicon or semiconductors compounds wafers (Nitrogen and Forming gas lines).
  • RTO: Rapid Thermal Oxidation (Oxygen line).
  • RTN: Rapid Thermal Nitridation (Ammonia line).
  • RTD: Rapid Thermal Diffusion from spin-on dopant (Nitrogen line).
  • Crystallization (Nitrogen line).
  • Contact Alloying (Nitrogen and Forming gas lines).
  • Solar applications for PV industry (Nitrogen line).

  • The system is compatible with wafers from 2'' up to 8'' as well as with pieces of wafers. The system is also equipped with a primary and a turbo pumps for a better control of the environment before and during the thermal process.

    II. Equipment description CMI

    The equipment is composed of:

  • Process chamber in stainless steel.
  • A furnace part equipped with 24 tubular infrared lamps.
  • 4 gas lines (O2, N2, NH3 and forming gas).
  • A primary pump.
  • A turbo pump.
  • The equipment is driven by a software interface (PIMS) but the following mannual operations are requested:

  • Sample loading/unloading.
  • Recipe selection and downloading.
  • PID selection and downloading.
  • Temperature sensor selection and setting up.
  • Your recipes as well as the PID tables associated are stored in the directory of your laboratory as shown on figure 1.b.

    RTP chamber
    Figure 1.a: Cross-section of the RTP chamber.

    Figure 1.b: Schematic of the RTP tool.

    III. Authorized and not authorized samples and treatments CMI

    The system is compatible with wafers from 2'' up to 8'' as well as pieces of wafers.

    The wafers and/or dies can be silicon, sapphire and glasses. For glasses, the temperature will be limited to the thermal strain point minus 50deg. Tha data has to be provided by the users. When it is possible, a RCA cleaning is highly recommended.

    For wafers with photoresist, kapton, parylen or polyimide (and all organic layers from a general point of view) and with copper or gold or any other metallic contaminants please contact CMI staff for an extended training.

    IV. Process description CMI

    A typical RTP recipe with a thermocouple regulation is composed of a minimum of 5 steps (see bold text in table 1) up to 50 steps. A typical RTP recipe with a pyrometer regulation is composed of a minimum of 9 steps (see bold text and red text in table 1) up to 50 steps.

    Step number Name Action Optional Parameters
    1 Chamber conditioning I Primary pumping No -
    2 Chamber conditioning II Secondary pumping Yes Duration
    Vacuum level
    3 Chamber filling N2 filling up to atmospheric pressure Yes Duration
    Gas (O2, N2, NH3 and forming gas)
    4 Gas setting Chamber filling with the process gas No Duration
    Gas (O2, N2, NH3 and forming gas)
    5 Ramp-up Sample heating up to 150deg Yes -
    6 Steady state Pyrometer pre-activation Yes -
    7 Ramp-up Sample heating up to 200deg Yes -
    8 Steady state Pyrometer activation Yes -
    9 Ramp-up Sample heating up to the set temperature No Duration
    (Ramp rate deg/s)
    10 Steady state Thermal treatment No Duration
    11 Ramp down Cool down of the sample No Duration
    (Ramp rate deg/s)
    12 Purge Open N2 purge valve Yes -

    Table 1: Description of the basic steps of a RTP recipe.

    V. Process window and standard preheating curve CMI

    When you start the run a process window appears.
    On this window, you have on the left a graph showing the temperature of the TC, the temperature of the pyrometer, the heating power and the temperature set point versus time. On the right, you see in live the TC and pyrometer temperatures, the heating power, the pressures, the temperature and pressure set points and the gas flows. At the bottom right corner, the button Stop can be used to abort manually the run (see figure 4).

    Once the run is ended, you can save the process data in your "historic" folder.
    The file can be converted in Excel file to have access to numerical data of temperature and vacuum. You can have also a view of temperatures and heating power during the run by opening directly the file with the PIMS software. On the figure 5, you can see standard curves for the Preheating recipe. The green line (Pyrometer temperature) is not exactly on the grey (set point) and red lines (TC temperature). This offset can be +/- 15deg. It is mainly due to the type of wafer that is used, the setting of the TC or the calibration of the pyrometer.
    If necessary, a more accurate calibration can be done with a test wafer which has to be very similar to your product wafer.

    Process window
    Figure 4: Process window.
    Historical window
    Figure 5: Historical window.

    VI. Abort routine CMI

    In two situations, the system can go in abort:

  • First: the tool has detected e.g. a problem on the cooling system or other error.
  • Second: voluntary stop because you have a too large oscillations of the heating power or error (see figure 7).

  • In both cases, you automatically come back on the main page of the PIMS software with an automatic routine during 240s containing purging and pumping sequences (see figure 8).

    Too large heating power oscillations
    Figure 7: Example of too large heating power oscillations.
    Process window after abort
    Figure 8: Process window after abort.

    VII. Temperature setting / controlling / monitoring CMI

    The tool is equipped with 2 complementary systems to set, control and monitor the temperature: 3 thermocouples (one for the regulation, TC1, and two for the monitoring, TC2 and TC3) and one pyrometer (see figure 1).

    Thermocouple regulation

    The regulation by thermocouple is done by direct contact measurement of the temperature on the wafer. The TC regulation is effective from the room temperature up to 1000deg in atmosphere and up to 800deg under vacuum. Outside of these ranges of temperature or pressure, a regulation with pyrometer has to be used and the thermocouple has to be withdrawn from the process chamber!!
    The TC regulation is valuable for all types of substrates (Si, glass, quartz, susceptor, sapphire...). The TC is in contact with the back side of silicon substrate or the susceptor. A clean back side is mandatory to ensure a good contact between the TC and the wafer and consequently a good reading of the temperature.

    Pyrometer regulation

    The regulation by pyrometer is done by the conversion of the infrared radiation emitted by the substrate into temperature. This conversion implies the creation of a conversion table (calibration table) which was done during the installation of the tool. The emissivity is dependent on the wafer itself and the layers that you have on it. A dedicated table could be necessary; in this case a test wafer with the same characteristics of the product wafer is needed.
    The regulation with pyrometer is effective from 500deg up to 1200deg in atmosphere and up to 1100deg under vacuum. Below 500deg, the thermocouple regulation has to be used!
    The pyrometer regulation is not valuable for transparent substrates like glass, quartz, sapphire... All the transparent samples have to be placed in a graphite/SiC susceptor.

    VIII. Loading and unloading samples CMI

    The system is compatible with wafers from 2'' up to 8'' as well as pieces of wafer or dies.

    Whatever the sample you process, it should never be placed directly on the metallic floor of the RTP chamber!

    For each size of wafer (4'', 6'' and 8'') and for dies, we have a set of picots in quartz (see figure 9). Each picot has to be placed in their dedicated holes (depending of the size of the wafer) in the floor of the chamber (see figures 10 and 11).

    Transparent samples compatible with high temperature treatments (quartz or sapphire) has to be place in the SiC susceptor. The susceptor corresponds to a 6'' wafer; it can accept 4'' wafers or smaller sizes. It can be used with or without cap. At last, the TC has to be placed in its dedicated hole in the susceptor.

    Figure 9: Set of accessories for 4'', 6'', 8'' and dies.

    Figure 10: 4'' wafer mounted on its 3 quartz picots.

    Figure 11: A picot above its emplacement in the RTP chamber.

    IX. Thermocouple positioning and thermocouple withdrawal CMI

    As mentioned previously:

  • TC cannot support temperature above 1000deg at atmospheric pressure.
  • TC cannot support temperature above 800deg under vacuum.
  • In both cases, the TC has to be withdrawn from the RTP chamber (see figures 12 and 13). To withdraw the TC, you have to unscrew the nut (see figures 14 and 15) in order to move the connector down (between 5 to 9 mm) and hide it in the metallic floor of the chamber. The TC should not anymore be visible (see figure 13).

    Figure 12: View of the TC in contact with the wafer placed on its 3 quartz picots.

    Figure 13: Same as figure 12 but wihtout the TC.

    Figure 14: Bottom part of the TC with the connector.

    Figure 15: Same as figure 14 but TC moved down by a few mm.
    (NB: the nut must be tight again in upper position before processing).

    X. How to use the system CMI

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