What is Ion Beam Machining?
Ion beam machining (IBM) is an important non-conventional manufacturing technology used in micro-/nanofabrication, using a stream of accelerated ions by electrical means in a vacuum chamber to remove, add, or modify the atoms on the surface of the object.
In IBM a stream of charged atoms (ions) of inert gas, such as argon, is accelerated in a vacuum by high energies and directed toward a solid workpiece.
The beam removes atoms from the workpiece by transferring energy and momentum to atoms on the surface of the object.
When an atom strikes a cluster of atoms on the workpiece, it dislodges between 0.1 and 10 atoms from the workpiece material.
IBM permits the accurate machining of virtually any material and is used in the semiconductor industry and in the manufacture of aspheric lenses.
The technique is also used for texturing surfaces to enhance bonding, for producing atomically clean surfaces on devices such as laser mirrors, and for modifying the thickness of thin films and membranes.
Working of Ion Beam Machining
Ion beam machining (IBM) is an atomic-bit machining process, which is used to machine a product with a high resolution of the order of 0.1 μm. Ions of inert gases like argon with high kinematic energy of the order of 10 KeV are used to bombard and eject atoms from the workpiece surface by elastic collision.
Unlike machine tool technologies of cutting, grinding, and lapping, IBM has no inherent reference surface; patterning mask acts as a reference.
IBM could be used as micromachining with a micro-ion beam of 1–2 μm diameter together with a high-precision position control machine tool.
IBM can also be used for aphorizing lenses, sharpening of diamond microtones knives and cutting tools, IC pattern etching, etc.
The cost of an IBM machine is very high, which increases the machining cost and makes the process uneconomical.
Ion Beam Machining Accuracy
Practical etching rates vary up to 2000 A (2 x 10-4 mm) per min. The accuracy of the etching process is considerably high mainly due to the small amount of material removal. Tolerances in the vicinity of + 50 Å (+ 5 x 10-mm) are possible.
Applications of Ion-Beam Machining
It is applied mostly in micro-machining (etching) of electronic components like computer parts, figuring optical surfaces and for the precision fabrication of fine wire dies in refractory materials.
Typical materials that can be etched include glass, alumina, quartz, crystals, silica, agates, porcelain, cermet. and numerous metals and oxides.
Advantages of Ion Beam Machining
Ion-beam has many advantages which include:
- The process is almost universal.
- No chemical reagents or etching compounds are required.
- There is no undercutting as with another chemical etching process.
- Etching rates are easily controlled.
Disadvantages of Ion Beam Machining
However, the process has many disadvantages which are as follows:
- It is relatively expensive.
- Etching rates are slow.
- Although virtually no heat is generated there is little possibility of some thermal or radiation damage.
FAQs
What are the advantages of ion beam machining?
The process is almost universal. No chemical reagents or etching compounds are required. There is no undercutting as with another chemical etching process. Etching rates are easily controlled.
How does an ion beam work?
The ions in a beam are produced by special instruments called ion sources. They gain speed when entering an electric field, which is produced in a particle accelerator, and are steered and focused by magnetic fields to travel in parallel trajectories inside a vacuum in a metal tube.
What is the mechanism of material removal in ion beam machining?
Ion milling material removal is fundamentally based on the sputtering process, whereby ion beam irradiation ejects atoms and clusters from a solid target. As energized ions collide with surface atoms, they transfer energy and impart momentum to the target material.
What is the purpose of ion milling?
Ion milling eliminates artifacts associated with traditional mechanical preparation methods and prepares surfaces with minimal strain or distortion. It is often the only way to create high quality surfaces or thin sections that are required in high resolution imaging and analysis in SEM and TEM.
What are the disadvantages of ion beam machining?
The main disadvantage of ion beam sputtering deposition is that the target area of the bombardment is too small, and the deposition rate is generally low. Moreover, ion beam sputter sputtering is also not suitable for depositing a large-area film of uniform thickness.
What are the disadvantages of ion beam lithography?
Expensive as compared to light lithography systems. Slower as compared to light lithography systems. Tri-level processing required.