Lithium Li Evaporation Process Notes

Thermal Evaporation of Lithium (Li)

The preferred method to deposit lithium films is by thermal evaporation. Depositing lithium via sputtering or e-beam evaporation is possible but the rate can be difficult to control due to the material's low melting point.

In order to successfully evaporate lithium, it is important that the material is not oxidized. Oxidized lithium will require more initial power to break through the oxide layer and then melt the metal. The power will then need to be brought down quickly as the oxide melts at a relatively high power causing the remaining lithium metal to flash evaporate quickly at that high power. To avoid oxidation, lithium should be kept either in oil or an argon inert atmosphere.

It is important to identify at what power the lithium melts. This can be done by manually ramping up the power and observing the material to determine when it melts. Once this power level is identified, it can be documented as the Ramp#1/Soak#1 set point in a recipe. Then, the power can be increased slowly until the desired deposition rate is reached. This power level becomes the Ramp#2/Soak#2 level in a recipe.

Suitable evaporation sources depend on the desired thickness of the lithium film. It is important to note that liquid lithium will eventually alloy and damage refractory metal coils and boats so the lifetime of these sources is limited. We have reported success in using tungsten coils to thermally evaporate lithium. As the power ramps up on the coils, the pellets melt and wet to the coils. With a slight increase in power, the lithium begins to evaporate. This method is a good way to tell if the lithium pellets are significantly oxidized, as oxidized lithium will not melt at lower powers. Also, the coils are typically made of three tungsten wires twisted together which allows for a longer lifetime of the source before failure due to the lithium alloying with the tungsten. If using a KJLC^© system, we would recommend our EVF43025W. If a tungsten boat is preferred, we would recommend our EVS20A015W. Alumina coated evaporation sources are not recommended for lithium evaporation because they will oxidize the lithium.

In cases where thicker lithium films are required and more material needs to be loaded into the source, we've had limited success using a shielded, tantalum crucible heater with an alumina crucible and tantalum insert. We recommend our EVCH14 with EVC6AO and EVC6AOTA if using a KJLC^© system.

Since lithium has a relatively high vapor pressure one must carefully consider executing lithium evaporation in any deposition system. At 300°C, lithium has a significantly high enough vapor pressure to cause ppm level contamination in a vacuum system. Limiting exposure can be as simple as lining the system with vacuum-rated aluminum or copper foil. Great care must be taken not to bridge electrical circuits inside the system with the foil. It's possible that even when using aluminum or copper foil, trace lithium can remain. For this reason, some users prefer to use only dedicated vacuum chambers for lithium deposition.

E-beam Evaporation of Lithium (Li)

Lithium is rated 'good' for e-beam evaporation. We recommend using a tantalum crucible liner to e-beam evaporate lithium. It is important to note that thermal evaporation is the preferred method to deposit lithium films due to lithium's low melting point and high vapor pressure at low temperatures. Lithium has a vapor pressure of 10^-4 Torr at just 407°C. Controlling the rate at these low temperatures via e-beam evaporation can be difficult.

In order to successfully evaporate lithium, it is important that the material is not oxidized. Oxidized lithium will require more initial power to break through the oxide layer and then melt the metal. The power will then need to be brought down quickly as the oxide melts at a relatively high power and the remaining lithium metal would then evaporate quickly or even perhaps splash from the crucible at these higher powers. To avoid oxidation, lithium should be kept either in oil or an argon inert atmosphere.

A key process note is to consider the fill volume in the e-beam application because 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. This is the most common cause of crucible liner failure. Placing too little material in the crucible 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.

Since lithium has a relatively high vapor pressure one must carefully consider executing lithium evaporation in any deposition system. At 300°C, lithium has a significantly high enough vapor pressure to cause ppm level contamination in a vacuum system. Limiting exposure can be as simple as lining the system with vacuum-rated aluminum foil. Great care must be taken not to bridge electrical circuits inside the system with the foil. It's possible that even when using aluminum foil, trace lithium can remain. For this reason, some users prefer to use only dedicated vacuum chambers for lithium deposition.

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