Magnetrons Magnetic Assemblies, Sputtering magnetrons magnet materials, magnetic designs, FAQ
1, Help us designs
Magnetrons Magnetic Assemblies – We do not make Magnetrons; we make the magnetic assemblies that enable these devices to operate effectively. In order to make a perfect magnet assembly, we would need to know the following:
1. What Type of magnetron is required?
a. Static Planar
b. Sweeping Planar
c. Rotatable Planar
2. What type of material is being sputtered?
3. If the material being sputtered is magnetic, do you have a hysteresis loop or magnetic material properties?
4. How thick is the target material?
5. What is the distance from the top of the magnetron to the back of the target material (TM-distance)? Can this be changed? If so, what is the minimum/maximum distance)?
6. What is the distance (range) from the top of the target to the substrate?
7. What is the current utilization of your process? What is the minimum expected?
8. What is the current uniformity of your process? What is the maximum deviation expected?
9. Geometric considerations:
a. Static planar (length, width, thickness)?
b. Sweeping planar (length, width, thickness, sweep distance)?
c. Rotating planar (diameter, thickness)?
d. Rotatable (Target inside diameter, magnetron thickness, length)?
10. Dynamic considerations:
a. Sweeping planar (sweep speed range)
b. Rotating planar (RPM range)
c. Rotatable (RPM range)
11. What is the goal of your redesign effort? (e.g. Enhanced utilization, improved uniformity, thicker targets, etc.)
12. Target cooling method?
a. Magnetron exposed to or magnetron separated from cooling media
Sputtering magnetrons can be designed and manufactured using all of the major classes of magnet materials (Ceramic, NdFeB, SmCo, or Alnico). However, greater than 90% of the magnetrons we produce today are designed and constructed from the rare-earth family of magnets – Neodymium Iron Boron (Nd-Fe-B) and Samarium Cobalt (Sm-Co).
Neodymium Iron Boron
Magnetrons produced from Nd-Fe-B provide the “biggest bang for the buck”. This is the strongest grade of magnetic material and well is well suited for magnetron design and construction. It is prone to corrosion, however, when submersed in liquids. As such, for magnetrons exposed to the cooling media, either a hermetic seal will be required or Sm-Co materials should be utilized. Additionally, these magnets have a typical upper thermal limit of about 100°C in assembly (specialty higher thermal limit grades are available up to 200°C).
Magnetrons produced from Sm-Co are strong, corrosion resilient, and thermally superior to Nd-Fe-B versions. This material costs between 2-3x as much as Nd-Fe-B versions. Although not anti-corrosive, it is vastly superior to the Nd-Fe-B. Its corrosion mode is “pitting”, which typically does not affect performance. Those magnetrons that are submersed in fluid should be constructed of Sm-Co materials. A secondary barrier is recommended to protect the magnet bond lines, however. Additionally, these magnets have a typical upper thermal limit of about 300°C in assembly. Special mechanical considerations need to be addressed at these temperatures, however, to eliminate thermal expansion mismatch and unexpected stresses in the assembly.
1. What type of utilization can I expect from these magnetrons?
2. How does Repumag guarantee homogeneity across the length of long magnetrons?
3. Will Repumag design my magnetron and let me manufacture it myself?
4. What benefit can Quadrature have on my process?
5. Can Quadrature be implemented into my magnetron configuration without changes the rest of my system?
1. a. Static Planar – typical utilization values are in the 10%-25% range. Some configurations can be adjusted to reach 40%
b. Sweeping Planar – typical utilization values are in the 20%-40% range. With proper magnetic shaping, it can be adjusted to 50%-%60%
c. Rotating Planar – typical utilization values are in the 20%-40% range. With proper magnetic shaping, it can be adjusted to exceed 50%
d. Rotatable – Typical utilization values are in the 60%-75% range. With proper shaping and dynamic integration, it can be designed to exceed 90%
2. MPCO checks and calibrates each of the permanent magnets used in the magnetron to within 1% of other equivalent magnets in the circuit. This guarantees a consistent product throughout its length.
3. Although MPCO has a seasoned engineering staff, providing consultancy only services are not part of MPCO ’s business models. As such, Repumag will assist with the design of optimized magnetrons but will require purchase of the manufactured product as well.
4. Quadrature magnets in a magnetron push more magnetic flux into the sputtering zone. This increase in flux density allows for the sputter of thicker targets, the sputter of magnetic targets, increases in ionization/deposition rates, or reduction in process power.
5. YES. Most OEM magnetrons are not designed efficiently from a magnetic standpoint. Quadrature magnets can be incorporated into most magnetrons without changing the envelope size.