High-Vacuum Carbon and Sputter Coaters – meeting higher demands
TurboQ from Quorum TechnologiesThe TurboQ Plus series are fully automated, modular coating systems for the deposition of electrically conductive carbon or metal films recommended for electron microscopic applications at low and medium-high resolutions. The TurboQ Plus can be acquired solely as a carbon coater (E), sputter coater (S) or as a combined system for carbon and sputter coating (ES). Due to the low background pressure, oxygen, nitrogen and water vapour are removed from the chamber. This helps avoiding chemical reactions during the sputtering process, which could otherwise lead to impurities or defects in the coatings. Lower scattering due to the improved vacuum also allows the deposition of high purity, amorphous carbon films of high density.
The TurboQ Plus can reach very fine grain sizes and thinner coatings. This is beneficial for imaging at ultra-high-resolutions in electron microscopy (magnifications > 200 000 x).
- Fully automated coating process (incl. download of process log files in .csv format)
- Built-in turbo pump, vacuum down to 1 x 10-6 mbar
- Large sample chamber: 150 mm Ø
- Fast turnover times / coating cycles
- Film-thickness monitor inlcuded
- E: carbon fibre or rod evaporation, optional: metal evaporation set-up
- S: sputter coating of noble metals, copper and nickel
- ES: a combined system both for sputtering and carbon coating
Further information
The TurboQ Plus series is available in three configurations:
- TurboQ E – an automatic carbon cord coater, can be optionally fitted to evaporate metals
- TurboQ S – an automatic sputter coater for non-oxidising metals, can be optionally fitted with a glow discharge insert
- TurboQ ES – a combined system both for sputtering and carbon coating
The different process inserts can easily be exchanged within seconds. The unit recognizes the replacement and the operating menu changes accordingly. A touch screen is used to enter coating parameters, display the coating sequence and show error messages. Multiple users can store up to 1000 recipes including all parameters. By awarding access rights, selected parameters can be protected against deletion and unauthorized modification. Only the administrator has access to all settings. A USB-port allows the download of recipes and process logs.
Several optional sample stages ensure the efficient and reproducible coating of samples within a wide range of geometries.
The fully automated process does not require tedious adjustment of a needle valve to control argon gas flow. Instead, the user can control the process vacuum, gas flow is adjusted automatically. Depending on the set gas value (vacuum), the voltage is adjusted accordingly and the desired sputter current (mA) is kept at a constant. This way, samples with strongly irregular topography can also be uniformly coated at low sputtering currents.
The glass chamber can be completely removed, granting easy access to the sample stage and facilitating the cleaning process.
Operating principle: carbon coater
Thin conductive layers of carbon are generated by resistive evaporation of carbon filaments or rods. A current of up to 90 A is needed to evaporate carbon from rod or filament. The pulsed carbon rod/fibre evaporation can be controlled by using an optional film thickness monitor. By evaporating a carbon fibre, up to 20 nm of carbon film can be deposited, whereas with carbon rods, thicknesses from 3 to 15 nm can be reached. Amorphous carbon films evaporated from a carbon rod in a turbo pumped system are much finer and of higher quality than those from a rotary pumped system. High quality carbon films are used as support films or surface replicas in TEM applications or for EBSD and high-resolution SEM applications.
Operating principle: magnetron sputtering
Magnetron sputter coaters (also referred to as "Cool Sputter Coaters") are equipped with a special magnet, which is located in the sputter head (cathode) near the target.
Benefits are:
- electrons are available for ionization of further process gas ions
- excessive heating is avoided
- optimisation of the utilisable target surface
During sputter coating, a vacuum is produced in a vacuum chamber and a process gas, preferably argon, is continuously leaked into the chamber. Argon has an optimal ion size and does not chemically react with other molecules.
Within a vacuum window from approx. 1 x 10-1 mbar to 7 x 10-3 mbar, process gas atoms are ionized in an electrical field, which creates a plasma. Positively charged argon atoms are accelerated towards the magnetron head with the target (cathode) and erode target atoms, which reach all surfaces within the vacuum chamber, including the sample to be coated.
The TurboQ Plus Series comes equipped with a turbomolecular pump and a special power supply, making it possible to sputter oxidising metals. Films sputtered from such materials exhibit a smaller grain size which allows imaging at higher resolutions in the SEM. In order to sputter oxidising metals like chromium, the oxide layer needs to be removed from the target’s surface (requires a current up to 150 mA) and the atmosphere in the work chamber needs to be oxygen-free.
Specifications
TurboQ S / E / ES | |
| Instrument case | 440 mm B x 551 mm D x 556 mm H (total height with coating head open: 860 mm) |
| Weight | 38 kg (ES version) |
| Work chamber | Borosilicate glass 150 mm ID x 220 mm H |
| Safety shield | Polyethylene terephthalate (PET) - cylinder |
| Display | 115.5 mm x 86.4 mm (active area) capacitive touch colour display |
| User interface | Intuitive full graphical interface with touch screen buttons, includes log of the last 1000 processes and USB-port. |
| Sputter target | Disc style 57 mm Ø x 0.5 mm thick chromium (Cr) target is fitted as standard. (S/ES versions only) |
Vacuum | |
| Turbomolecular pump | Internally mounted, 70 l/s air-cooled |
| Rotary pump | 50 l/min. two-stage rotary pump with oil mist filter (order separately, see AG-DS102) |
| Vacuum measurement | full range gauge |
| Typical ultimate vacuum | ∼1x10-6 mbar (in a clean system after pre-pumping with dry nitrogen gas) |
| Sputter vacuum range | Between 5x10-3 and 1x10-1 mbar |
| Specimen stage | 50 mm Ø rotation stage. Rotation speed 8-20 RPM. For alternative stages see options and accessories |
Applications | |
| Sputtering | 0–150 mA to a pre-determined thickness (with FTM) or by the built-in timer. The maximum sputtering time is 60 minutes (without breaking vacuum and with built in cooling periods) |
| Carbon evaporation | A robust, ripple free DC power supply featuring pulse evaporation or ensures reproducible carbon evaporation from rod or fibre sources. Current pulse: 1–90 A |
| Metal evaporation/aperture cleaning insert | or thermal evaporation of metals from filaments or boats. For cleaning SEM or TEM apertures a standard molybdenum boat (supplied) can be fitted. The metal evaporation head is set up for downwards evaporation, but upward evaporation can be achieved by fitting two terminal extensions (supplied). |
Further Information | |
| Gases | Argon sputtering process gas, 99.999% (S and ES versions) |
| Electrical supply | 90–250 V 50/60 Hz 1400 VA including rotary pump power. 110/240 V voltage selectable. |
| Conformity | CE conformity: Power factor correction. Complies with the current legislation (CE Certification) and ensures efficient use of power, which means reduced running costs |
Options and accessories | |
| 10879 | Carbon rod evaporation insert for 3.05 mm Ø rods (E and ES only). Includes manual rod shaper and 3.05 mm Ø x 300 mm (pack of ten) carbon rods. |
| 10262 | Glow discharge insert. Used to modify surface properties (e.g. hydrophobic to hydrophilic conversion) (S and ES versions only). Can be retrofitted. |
| 10726 | Additional sputter insert for quick metal change (E and ES versions only). NB: This is an entire sputtering assembly; individual targets can also be purchased. |
| 10360 | Variable angle 'Rotacota' rotary planetary specimen stage (rotational speed 8-20 RPM). 50 mm Ø specimen platform with six stub positions for 15 mm, 10 mm, 6.5 mm or 1/8" pin stubs. Stage rotation speed variable between 8–20 RPM. |
| 10458 | Flat rotation specimen stage for 4"/100 mm wafers, includes gear box for increased coverage. Stage rotation speed variable between 8-20 RPM. |
| 10454 | Film thickness monitor (FTM) attachment. Including oscillator, feed-through, quartz crystal holder and quartz crystals. (Included as standard) |
| 10429 | extra vacuum chamber (220 mm in height, 150 mm ID) |
Applications
Thin carbon layers are evaporated onto non-conductive samples in electron microscopy for applications like EDX or WDX to prevent charging of the sample. Carbon has a low x-ray absorption, assuring better detection of x-rays than with metal coatings.
Sputter coaters are used to deposit a thin metal layer on the surface of a sample/substrate. For electron microscopy applications, electrically conductive films need to be deposited on non-conductive surfaces, to prevent electrons from the microscope's electron beam from accumulating on the sample surface, causing the latter to become charged. Such a charge would prevent imaging of these surfaces with the SEM. The desired films should be extremely thin, but electrically conductive, with a thickness of 3 - 20 nm.
Chromium or high-vacuum sputter coaters have become more established in the past few years. Their advantages are a virtually “clean” vacuum, due to the application of a turbomolecular pump, and a powerful magnetron head, capable of removing the oxide layer on the target material. Sputter currents as high as 150 mA enable the highly efficient removal of oxide layers on oxidising targets. Rotary pumped sputter coaters do not support sputtering of oxidising metals.
The deposition of carbon films also benefits from lower pressure in the work chamber. Under high-vacuum conditions, very thin, amorphous carbon layers can be produced. These can be used as sample support films or to create surface replicas for TEM applications.
Glow discharge is used to alter the properties of sample surfaces. TEM carbon support films are hydrophobic after fabrication. After treatment with glow discharge, they become hydrophilic, thus allowing an even spread of aqueous solutions.
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