Frequently Asked Questions:
• Do all sputtering targets need to be bonded to a backing plate?
NO. There are many different types of sputtering and deposition systems (Tools), cathode assemblies and target material compositions; all of which have different requirements for actual use in Plasma Deposition. In general, for magnetically enhanced cathode assemblies and planar diode cathodes, the geometrical size and cathode design are the determining factors for metallic bonding requirements. Large circular cathodes and most rectangular cathodes require targets be bonded to some type of backing plate. Very large linear cathodes, like those used in large area depositions such as Architectural Glass or Photovoltaic applications, are an exception to this rule; these larger target sizes are often directly clamped into the water cooled body of the cathode. Smaller circular targets that are typically clamped into the cathode housing or held with a magnetic keeper, depending on the cathode manufacturer's design do not require a backing plate. For most metal and metal alloy targets these can be supplied in full thickness, usually 0.25" (6mm) and clamped directly into the cathode assembly. For composite and ceramic type targets, they generally are better facilitated by bonding to an OFE copper backing plate to enhance the cooling efficiency and mechanical strength. Most larger circular targets are generally bonded to backing plates as well. Again, this is dictated by the cathode manufactures design.
• What is your lead time on sputtering targets?
Plasmaterials, Inc. stocks many of the so called "standard Materials" of common elements, compositions and sizes which are available for immediate delivery. Usually these can be shipped to the customer on the same day that they are ordered.For most standard compositions, but non standard sizes, Plasmaterials, Inc. keeps a supply of plate and sheet stock in a variety of thicknesses that can be quickly machined into the required dimensional tolerances for non standard geometries. These materials can usually be finished machined and shipped within a few days. For non standard compositions and/or sizes that have to be fabricated completely from the starting raw materials, the average delivery runs around 3 to 4 weeks after receipt of order. Actual delivery is dependent on the production backlog at the time of order placement. The anticipated delivery date is provided on the Confirmation Order which is sent to the customer shortly after receipt of the order.
• Do you make custom compositions and sizes?
YES. Plasmaterials, Inc. has a vast experience in producing many types of "special Compositions" over its past 25 years in operation. Through the use of vacuum casting and/or powder metallurgical techniques, many different stoichiometric compositions can be produced as either alloys, composites or ceramics. Plasmaterials, Inc. is customer driven and strives to produce the specific requirements of its broad customer base.There may be physical constraints on certain material compositions as to size or geometry depending on physical characteristics such as ductility, toughness, coefficient of expansion, conductivity, etc. which may restrict how a particular material will perform in operation, but many of these restrictions can be overcome with the engineering capabilities available at Plasmaterials, Inc.
• What is the maximum thickness of magnetic materials?
The maximum thickness of a specific magnetic material that can be operated in a magnetically enhanced cathode assembly is dependent on the magnetic coercivity of the material to be sputtered or deposited (Bmax) and the magnetic strength of the magnets employed in the cathode assembly design. Different magnetic materials, i.e. ferromagnetic (Co, Fe, Ni, etc.) and rare earth metals ( Nd, Sm/Co,YCo5, etc.) that are used in magnetically enhanced cathode assemblies have different magnetic strengths and properties. So the exact thickness of any given magnetic sputtering target comprised of a magnetic composition is highly dependent on the specific magnetic composition and design of the customer's cathode assembly. In general, a good rule of thumb to follow would be to limit the overall thickness of a magnetic target material to less than 0.125" (3.1mm), usually around 0.100" (2.5mm).
For diode sputtering system there is no magnetic limitation associated with the sputtering target thickness, although there may be some limitations associated with effectively being able to cool the target during plasma deposition.
• What is the maximum power density that can be used in the plasma for a sputtering target?
The maximum power density that a sputtering target can sustain under equilibrium conditions is highly dependent on the target material in question and the cathode design. Deposition rate is a function of both power density and magnetic field at the target surface. The overall restriction or limitation to power density is generally heat dissipation. The exothermic atomic bond breaking at the target surface due to the momentum transfer of the impinging ions and the target atoms generates a great deal of heat. This heat needs to be dissipated through the target thickness from the front surface of the target where the heat is generated to the back surface of the target where it is cooled through the cathode assembly. For highly conductive metallic targets, this heat dissipation is handled quite readily. For thermally insulating materials, it is less so. A general rule of thumb, which unfortunately has many exceptions, is to limit the maximum power density for metallic materials to 250 watts/sq. in. of target surface area for direct water cooled targets and 100 watts/sq. in. with indirect cooling. For ceramic or insulating targets the maximum power density should be limited to 65 watts/sq. in. for direct cooling and 30 watts/sq. in. for indirect.
• What crucible liner do we use for a given material?
The purpose of a crucible liner in an Electron Beam evaporation source is to limit the heat dissipation/loss from the material being deposited to the water cooled hearth and to prevent any damaging reaction with the source. The electron beam source generates a stream of electrons from the filament that produces enough heat within the material to either melt the material and create a vapor from the liquid or sublimate it from the solid. Maintaining a constant thermal equilibrium condition can be difficult if much of the heat is dissipated through the water cooled hearth of the electron beam source. For this reason, it is quite often advantageous to utilize a crucible liner to segregate the deposition material from the cooling body of the hearth. Additionally, many material compositions are quite reactive with other materials. This is especially true in the molten or liquid form at elevated temperatures. To prevent the material that is being deposited from reacting or alloying with either the copper hearth or the crucible liner itself, proper care must be taken to select the correct composition of the liner material. Contact your Plasmaterials, Inc, Sales Engineer or local representative for assistance in selecting the proper liner and size for the specific material that you are interested in depositing.
• How much do the sputtering targets cost?
Sputtering targets are produced from high purity elemental materials that are combined and fabricated in a variety of ways to produce a particular shape or geometry of a specific composition and purity. This means that the cost to produce a target is a sum of the raw material costs, the size of the target and the cost of fabrication or consolidation. Unfortunately, the cost of the raw materials utilized to produce these targets varies on a daily basis. To provide the most competitive cost bases to our customer base, Plasmaterials, Inc. offers an, "Up to the minute" pricing structure calculated at the time that the Price/Delivery quotation is offered. The Plasmaterials costing department evaluates each individual requirement based on current pricing conditions and offers a timely and competitive offering.
• How are precious metals purchased?
Precious metals may be purchased in several different ways, depending on the requirements of the customer. The Plasmaterials, Inc. "Precious metal Addendum" (see specifications on the Plasmaterials, Inc's web site at Plasmaterials.com) which defines the "Terms and Conditions" for several different payment options that a customer may choose from is included in the price quotation. Depending on the actual amount of precious metal contained within a specified target, some smaller geometry targets may be offered at a fixed price. All precious metal offerings are based on the current cost of the metal to be utilized in the target. The price offering is valid for three days from the time of issue.
• Do you accept credit Cards?
YES. Plasmaterials, Inc. is pleased to accept credit cards when given at the time of order placement. Valid Visa, Master Card and American Express Cards are accepted as long as identification and qualification can be verified. Actual charges will not be posted until the time of order shipment.
• Do you bond third party targets?
YES. Plasmaterials, Inc. offers all metal bonding services to any customer of third party sputtering targets to customer supplied, or Plasmaterials, Inc. supplied, backing plates in any size, composition or configuration. This offer also applies to any OEM or independent sputtering target manufacturer as well.
• What size target do I need?
Plasmaterials, Inc's. sputtering targets are designed and engineered to fit the specific cathode assemblies used in the systems and tools of our broad customer base. For the most part, the geometrical configurations and constraints of the targets are dictated by these designs. Although thicknesses can vary somewhat, the outer perimeter of the targets are generally fixed. The exact size and size limitations of the required sputtering target geometry are generally provided in the Operations Manual of the equipment or cathode manufacturer. Simply provide this sizing information, along with the required purity requirements and material composition to Plasmaterials, Inc. for a price and delivery quotation. If there are any doubts about these specific issues, please contact your Plasmaterials, Inc. Sales Engineer directly at +1(925) 447-4030 or contact us at firstname.lastname@example.org.