Chromium Cr Evaporation Process Notes

Thermal Evaporation of Chromium (Cr)

Chromium can be problematic to thermally evaporate because it will sublime under high temperatures. In order to perform thermal evaporation, a material's temperature must be raised to the point where its equilibrium vapor pressure is 1E^-2 Torr. This provides for good deposition rates in systems with "normal" source-to-substrate geometries. According to chromium's vapor pressure curve, the necessary temperature for this to occur is 1,400°C.

Chromium (Cr) Vapor Pressure Chart

Since its melting point is higher (1,857°C), it will sublime from a solid phase. This presents two possible issues. One, heating anything to 1,400°C might generate an unacceptably high thermal load in the chamber. Two, the heat transfer mechanism of solid chromium pieces is almost entirely by thermal radiation which means the heater must be much higher than 1,400°C.

There are two main recommendations for thermally evaporating chromium. The first option is to use chrome plated tungsten rods. These electroplated rods are ideal for depositing very thin adhesion layers. Because the chromium is plated directly on the tungsten rod, heat transfer is by conduction. Sublimation occurs easily and quickly, compared with evaporating from a boat, and affords a potentially much lower thermal load on the chamber. The main disadvantages of these rods are the limited amount of chromium available from each rod and the fact that they are one-time use sources.

The second option is to evaporate the material from a refractory boat. We have reported success in the past using a thin width, thick gauge, high current tungsten boat such as our EVS20A015W. Using this boat, we sublimated chromium pieces with a standard 3.3V 375A KJLC^® power supply. There is no interaction between the sublimating chromium and the tungsten boat. The rates are fairly easy to control at 1-5 Angstroms/sec. It is important to note that while the power supply is capable of 1,200W, a lower power was used during sublimation.

E-beam Evaporation of Chromium (Cr)

Chromium can be e-beam evaporated from a FABMATE^®, graphite, or tungsten crucible liner. A key process note is to consider the fill volume of the crucible liner. We find that the melt level of a material in the crucible directly affects the success of the crucible liner. Overfilling the crucible will cause the material to spill over and create an electrical short between the liner and the hearth. The outcome is cracking in the crucible liner. This is the most common cause of crucible liner failure. Placing too little material in the liner or evaporating too much material before refilling can be detrimental to the process as well. When the melt level is below 30%, the e-beam is likely to strike the bottom or walls of the crucible which immediately results in breakage. Our recommendation is to fill the crucible between 2/3 and 3/4 full to prevent these difficulties.

Crucible liners should be stored in a cool, dry place and always handled with gloves or forceps.

Chromium can also be run directly from the copper hearth of the e-gun. Because of this, some customers prefer to use a pre-machined slug (or starter source) that is directly placed in the hearth pocket. The two main benefits of using a starter source are ease of use and handling as well as superior packing density. Because not using a crucible liner is not always an option, especially in shared systems, some customers will use a copper crucible liner and place the starter source in the copper crucible liner instead of placing directly in the hearth.

KJLC^® can produce these starter sources. Contact us by clicking here with your e-gun manufacturer, pocket size, and number of pockets in order for us to produce a quote.

E-beam Crucible Liner Fill Rate Calculator

Instructions for use:
Input the Crucible Liner Volume, Select Material (if not available in menu, manually input Material Density in g/cm³), and input fill rate %.

KJLC recommends a fill rate between 67-75%. Overfilling the crucible will cause the material to spill over and create an electrical short between the liner and the hearth causing the crucible to crack. Placing too little material in the crucible or allowing the melt level to get too low can be detrimental to the process as well. When the melt level is below 30%, the e-beam is likely to strike the bottom or walls of the crucible which immediately results in breakage.

The fill rate above assumes that the material is fully melted and does not take into account packing density. It should be noted that the crucible liner may need to be loaded multiple times, pre-melted, and topped off in order to achieve the final desired melt level/fill rate. When loading the crucible, do not load more than 80% of the height of the crucible liner.

This calculator is for estimation purposes only.

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Crucible Liner Volume (in cc):

Material:
-- Please Select -- Aluminum Aluminum Antimonide Aluminum Arsenide Aluminum Bromide Aluminum Carbide Aluminum Fluoride Aluminum Nitride Aluminum Oxide Aluminum Phosphide Aluminum, 1% Copper Aluminum, 1% Silicon Antimony Antimony Oxide Antimony Selenide Antimony Sulfide Antimony Telluride Arsenic Arsenic Oxide Arsenic Selenide Arsenic Sulfide Arsenic Telluride Barium Barium Chloride Barium Fluoride Barium Oxide Barium Sulfide Barium Titanate Beryllium Beryllium Carbide Beryllium Chloride Beryllium Fluoride Beryllium Oxide Bismuth Bismuth Fluoride Bismuth Oxide Bismuth Selenide Bismuth Sulfide Bismuth Telluride Bismuth Titanate Boron Boron Carbide Boron Nitride Boron Oxide Boron Sulfide Cadmium Cadmium Antimonide Cadmium Arsenide Cadmium Bromide Cadmium Chloride Cadmium Fluoride Cadmium Iodide Cadmium Oxide Cadmium Selenide Cadmium Sulfide Cadmium Telluride Calcium Calcium Fluoride Calcium Oxide Calcium Silicate Calcium Sulfide Calcium Titanate Calcium Tungstate Carbon Cerium Cerium (III) Oxide Cerium (IV) Oxide Cerium Fluoride Cesium Cesium Bromide Cesium Chloride Cesium Fluoride Cesium Hydroxide Cesium Iodide Chiolite Chromium Chromium (II) Bromide Chromium Boride Chromium Carbide Chromium Chloride Chromium Oxide Chromium Silicide Cobalt † Cobalt Bromide Cobalt Chloride Cobalt Oxide Copper Copper Chloride Copper Oxide Copper Sulfide Cryolite Dysprosium Dysprosium Fluoride Dysprosium Oxide Erbium Erbium Fluoride Erbium Oxide Europium Europium Fluoride Europium Oxide Europium Sulfide Gadolinium † Gadolinium Carbide Gadolinium Oxide Gallium Gallium Antimonide Gallium Arsenide Gallium Nitride Gallium Oxide Gallium Phosphide Germanium Germanium (II) Oxide Germanium (III) Oxide Germanium Nitride Germanium Telluride Glass, Schott^® 8329 Gold Hafnium Hafnium Boride Hafnium Carbide Hafnium Nitride Hafnium Oxide Hafnium Silicide Holmium Holmium Fluoride Holmium Oxide Inconel^® Indium Indium (I) Oxide Indium (I) Sulfide Indium (II) Sulfide Indium (II) Telluride Indium (III) Oxide Indium (III) Sulfide Indium (III) Telluride Indium Antimonide Indium Arsenide Indium Nitride Indium Phosphide Indium Selenide Indium Tin Oxide Iridium Iron (II) Oxide Iron (III) Oxide Iron † Iron Bromide Iron Chloride Iron Iodide Iron Sulfide Kanthal Lanthanum Lanthanum Boride Lanthanum Bromide Lanthanum Fluoride Lanthanum Oxide Lead Lead Bromide Lead Chloride Lead Fluoride Lead Iodide Lead Oxide Lead Selenide Lead Stannate Lead Sulfide Lead Telluride Lead Titanate Lithium Lithium Bromide Lithium Chloride Lithium Fluoride Lithium Iodide Lithium Niobate Lithium Oxide Lutetium Lutetium Oxide Magnesium Magnesium Aluminate Magnesium Bromide Magnesium Chloride Magnesium Fluoride Magnesium Iodide Magnesium Oxide Manganese Manganese (II) Oxide Manganese (III) Oxide Manganese (IV) Oxide Manganese Bromide Manganese Chloride Manganese Sulfide Mercury Mercury Sulfide Molybdenum Molybdenum Boride Molybdenum Carbide Molybdenum Oxide Molybdenum Silicide Molybdenum Sulfide Neodymium Neodymium Fluoride Neodymium Oxide Nichrome IV^® Nickel † Nickel Bromide Nickel Chloride Nickel Oxide Nickel/Iron † Nimendium † Niobium Niobium (II) Oxide Niobium (III) Oxide Niobium (V) Oxide Niobium Boride Niobium Carbide Niobium Nitride Niobium Telluride Niobium-Tin Osmium Osmium Oxide Palladium Palladium Oxide Parylene Permalloy^® † Phosphorus Phosphorus Nitride Platinum Platinum Oxide Plutonium Polonium Potassium Potassium Bromide Potassium Chloride Potassium Fluoride Potassium Hydroxide Potassium Iodide Praseodymium Praseodymium Oxide PTFE Radium Rhenium Rhenium Oxide Rhodium Rubidium Rubidium Chloride Rubidium Iodide Ruthenium Samarium Samarium Oxide Samarium Sulfide Scandium Scandium Oxide Selenium Silicon Silicon (II) Oxide Silicon (IV) Oxide Silicon (N-type) Silicon (P-type) Silicon Boride Silicon Carbide Silicon Nitride Silicon Selenide Silicon Sulfide Silicon Telluride Silver Silver Bromide Silver Chloride Silver Iodide Sodium Sodium Bromide Sodium Chloride Sodium Cyanide Sodium Fluoride Sodium Hydroxide Spinel Strontium Strontium Chloride Strontium Fluoride Strontium Oxide Strontium Sulfide Strontium Titanate Sulfur Supermalloy^® † Tantalum Tantalum Boride Tantalum Carbide Tantalum Nitride Tantalum Pentoxide Tantalum Sulfide Technetium Tellurium Terbium Terbium Fluoride Terbium Oxide Terbium Peroxide Thallium Thallium Bromide Thallium Chloride Thallium Iodide Thallium Oxide Thorium Thorium Bromide Thorium Carbide Thorium Fluoride Thorium Oxide Thorium Oxyfluoride Thorium Sulfide Thulium Thulium Oxide Tin Tin Oxide Tin Selenide Tin Sulfide Tin Telluride Titanium Titanium (II) Oxide Titanium (III) Oxide Titanium (IV) Oxide Titanium Boride Titanium Carbide Titanium Nitride Tungsten Tungsten Boride Tungsten Carbide Tungsten Disulfide Tungsten Oxide Tungsten Selenide Tungsten Silicide Tungsten Telluride Uranium Uranium (II) Sulfide Uranium (III) Oxide Uranium (IV) Oxide Uranium (IV) Sulfide Uranium Carbide Uranium Fluoride Uranium Phosphide Vanadium Vanadium (IV) Oxide Vanadium (V) Oxide Vanadium Boride Vanadium Carbide Vanadium Nitride Vanadium Silicide Ytterbium Ytterbium Fluoride Ytterbium Oxide Yttrium Yttrium Aluminum Oxide Yttrium Fluoride Yttrium Oxide Zinc Zinc Antimonide Zinc Bromide Zinc Fluoride Zinc Nitride Zinc Oxide Zinc Selenide Zinc Sulfide Zinc Telluride Zirconium Zirconium Boride Zirconium Carbide Zirconium Nitride Zirconium Oxide Zirconium Silicate Zirconium Silicide
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Density of the material in g/cm³:

Fill Rate %:

Result

See highlighted results that match your result in the table below.

Material Needed to Deposit a 1 Micron Film Calculator

Instructions for use:
Select source type, input distance from source to substrate and Select Material (if not available in menu, manually input Material Density in kg/m³).

This calculator is for estimation purposes only. The estimated mass is that needed to produce a desired film thickness (1 micron in this case) on a flat substrate at a point directly above the source, accounting for the approximate plume distribution of the selected source type. It does not account for any expected nonuniformity in thickness over a larger substrate area. More complex geometries, e.g. those with offset and/or tilted sources, may have higher material requirements. The estimated mass is for the film deposition only; additional margin should be included to account for loss during ramp-up, burn-in, stabilisation and ramp-down.

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Source:
Point Directional - Thermal Boat Directional - EBeam Directional - LTE/HTE

Distance of source to substrate (in cm):

Material:
-- Please Select -- Aluminum Aluminum Antimonide Aluminum Arsenide Aluminum Bromide Aluminum Carbide Aluminum Fluoride Aluminum Nitride Aluminum Oxide Aluminum Phosphide Aluminum, 1% Copper Aluminum, 1% Silicon Antimony Antimony Oxide Antimony Selenide Antimony Sulfide Antimony Telluride Arsenic Arsenic Oxide Arsenic Selenide Arsenic Sulfide Arsenic Telluride Barium Barium Chloride Barium Fluoride Barium Oxide Barium Sulfide Barium Titanate Beryllium Beryllium Carbide Beryllium Chloride Beryllium Fluoride Beryllium Oxide Bismuth Bismuth Fluoride Bismuth Oxide Bismuth Selenide Bismuth Sulfide Bismuth Telluride Bismuth Titanate Boron Boron Carbide Boron Nitride Boron Oxide Boron Sulfide Cadmium Cadmium Antimonide Cadmium Arsenide Cadmium Bromide Cadmium Chloride Cadmium Fluoride Cadmium Iodide Cadmium Oxide Cadmium Selenide Cadmium Sulfide Cadmium Telluride Calcium Calcium Fluoride Calcium Oxide Calcium Silicate Calcium Sulfide Calcium Titanate Calcium Tungstate Carbon Cerium Cerium (III) Oxide Cerium (IV) Oxide Cerium Fluoride Cesium Cesium Bromide Cesium Chloride Cesium Fluoride Cesium Hydroxide Cesium Iodide Chiolite Chromium Chromium (II) Bromide Chromium Boride Chromium Carbide Chromium Chloride Chromium Oxide Chromium Silicide Cobalt † Cobalt Bromide Cobalt Chloride Cobalt Oxide Copper Copper Chloride Copper Oxide Copper Sulfide Cryolite Dysprosium Dysprosium Fluoride Dysprosium Oxide Erbium Erbium Fluoride Erbium Oxide Europium Europium Fluoride Europium Oxide Europium Sulfide Gadolinium † Gadolinium Carbide Gadolinium Oxide Gallium Gallium Antimonide Gallium Arsenide Gallium Nitride Gallium Oxide Gallium Phosphide Germanium Germanium (II) Oxide Germanium (III) Oxide Germanium Nitride Germanium Telluride Glass, Schott^® 8329 Gold Hafnium Hafnium Boride Hafnium Carbide Hafnium Nitride Hafnium Oxide Hafnium Silicide Holmium Holmium Fluoride Holmium Oxide Inconel^® Indium Indium (I) Oxide Indium (I) Sulfide Indium (II) Sulfide Indium (II) Telluride Indium (III) Oxide Indium (III) Sulfide Indium (III) Telluride Indium Antimonide Indium Arsenide Indium Nitride Indium Phosphide Indium Selenide Indium Tin Oxide Iridium Iron (II) Oxide Iron (III) Oxide Iron † Iron Bromide Iron Chloride Iron Iodide Iron Sulfide Kanthal Lanthanum Lanthanum Boride Lanthanum Bromide Lanthanum Fluoride Lanthanum Oxide Lead Lead Bromide Lead Chloride Lead Fluoride Lead Iodide Lead Oxide Lead Selenide Lead Stannate Lead Sulfide Lead Telluride Lead Titanate Lithium Lithium Bromide Lithium Chloride Lithium Fluoride Lithium Iodide Lithium Niobate Lithium Oxide Lutetium Lutetium Oxide Magnesium Magnesium Aluminate Magnesium Bromide Magnesium Chloride Magnesium Fluoride Magnesium Iodide Magnesium Oxide Manganese Manganese (II) Oxide Manganese (III) Oxide Manganese (IV) Oxide Manganese Bromide Manganese Chloride Manganese Sulfide Mercury Mercury Sulfide Molybdenum Molybdenum Boride Molybdenum Carbide Molybdenum Oxide Molybdenum Silicide Molybdenum Sulfide Neodymium Neodymium Fluoride Neodymium Oxide Nichrome IV^® Nickel † Nickel Bromide Nickel Chloride Nickel Oxide Nickel/Iron † Nimendium † Niobium Niobium (II) Oxide Niobium (III) Oxide Niobium (V) Oxide Niobium Boride Niobium Carbide Niobium Nitride Niobium Telluride Niobium-Tin Osmium Osmium Oxide Palladium Palladium Oxide Parylene Permalloy^® † Phosphorus Phosphorus Nitride Platinum Platinum Oxide Plutonium Polonium Potassium Potassium Bromide Potassium Chloride Potassium Fluoride Potassium Hydroxide Potassium Iodide Praseodymium Praseodymium Oxide PTFE Radium Rhenium Rhenium Oxide Rhodium Rubidium Rubidium Chloride Rubidium Iodide Ruthenium Samarium Samarium Oxide Samarium Sulfide Scandium Scandium Oxide Selenium Silicon Silicon (II) Oxide Silicon (IV) Oxide Silicon (N-type) Silicon (P-type) Silicon Boride Silicon Carbide Silicon Nitride Silicon Selenide Silicon Sulfide Silicon Telluride Silver Silver Bromide Silver Chloride Silver Iodide Sodium Sodium Bromide Sodium Chloride Sodium Cyanide Sodium Fluoride Sodium Hydroxide Spinel Strontium Strontium Chloride Strontium Fluoride Strontium Oxide Strontium Sulfide Strontium Titanate Sulfur Supermalloy^® † Tantalum Tantalum Boride Tantalum Carbide Tantalum Nitride Tantalum Pentoxide Tantalum Sulfide Technetium Tellurium Terbium Terbium Fluoride Terbium Oxide Terbium Peroxide Thallium Thallium Bromide Thallium Chloride Thallium Iodide Thallium Oxide Thorium Thorium Bromide Thorium Carbide Thorium Fluoride Thorium Oxide Thorium Oxyfluoride Thorium Sulfide Thulium Thulium Oxide Tin Tin Oxide Tin Selenide Tin Sulfide Tin Telluride Titanium Titanium (II) Oxide Titanium (III) Oxide Titanium (IV) Oxide Titanium Boride Titanium Carbide Titanium Nitride Tungsten Tungsten Boride Tungsten Carbide Tungsten Disulfide Tungsten Oxide Tungsten Selenide Tungsten Silicide Tungsten Telluride Uranium Uranium (II) Sulfide Uranium (III) Oxide Uranium (IV) Oxide Uranium (IV) Sulfide Uranium Carbide Uranium Fluoride Uranium Phosphide Vanadium Vanadium (IV) Oxide Vanadium (V) Oxide Vanadium Boride Vanadium Carbide Vanadium Nitride Vanadium Silicide Ytterbium Ytterbium Fluoride Ytterbium Oxide Yttrium Yttrium Aluminum Oxide Yttrium Fluoride Yttrium Oxide Zinc Zinc Antimonide Zinc Bromide Zinc Fluoride Zinc Nitride Zinc Oxide Zinc Selenide Zinc Sulfide Zinc Telluride Zirconium Zirconium Boride Zirconium Carbide Zirconium Nitride Zirconium Oxide Zirconium Silicate Zirconium Silicide
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Density of the material in kg/m³:

Multiplier:

Mass for 1 micron layer