What is precision ion polishing system
Precision ion polishing system
is an instrument used in the field of material science. It has a fast sample preparation speed, allowing high-quality transmission electron microscopy (TEM) samples
to be prepared with minimal cost and effort. The instrument can be operated quickly and easily because it is equipped with a low-energy ion gun, which is particularly suitable for energy-sensitive sample thinning. A precision ion polishing system is typically used with a liquid nitrogen cold stage and is particularly suitable for the polishing of temperature-sensitive samples. The main use of this instrument is the preparation of TEM samples of various materials such as ceramics, semiconductors, metals, alloys, etc.
Features of precision ion polishing system
A. Precision ion polishing system
has wide materials applicability. Precision ion polishing systems
can be used to prepare transmissive thin film samples for almost all solid materials, such as metals, non-metals, semiconductors, minerals, bones, teeth, etc.
B. The ion bombardment of the material does not have a significant tendency to select the various phase regions and generally results in a thin region of relatively uniform thickness. A wider choice of field of view is available for observation in the electron microscope, and the sample can be tilted at a large angle to obtain the desired results.
C. Samples prepared by ion bombardment are very clean and often have an oxide passivation film or other electrolytic products on the sample surface. However, this method affects the imaging quality when observed at high magnification, and it is easy to mix with fine precipitates inside the material.
D. The use of an ion polishing system
allows for unidirectional polishing from one side of the sample. This technique is particularly suitable for the study of permeable growth layers, deposition, and other surface research work. In addition, the ion polishing technique
does not expose the operator to acids, bases, and other harmful reagents, which means that the safety and health of the operator are not compromised.
Working principle of precision ion polishing system
The technique of precision ion polishing belongs to the category of ion beam processing. The precision ion polishing system works on the following principles:
a. The ionization of argon gas is carried out at high pressure, and then the ionized argon ions bombard the sample surface under the action of the electric field.
b. Under the continuous bombardment of argon ions, the sample is slowly thinned until it meets the sample preparation requirements.
This working principle refers to the method of bombarding the sample surface with a high-energy ion beam, which causes elastic collisions with atoms on the sample surface; when the energy of the atoms on the sample surface increases above the escape work of the atoms, they fly away from the sample, thus causing the sample surface to continuously lose atoms - polishing. For example, use a precision ion polishing instrument to polish the dilute gas argon gas -- in the vacuum environment of a high voltage electric field, when the argon ion passes through the central hole of the disk cathode, it will produce a high-energy particle beam to bombard the sample surface after accelerating and focusing; the high-energy ions will collide elastically with the sample surface; when the energy of the atoms on the surface of the sample increases above the work of escape of the atoms, they fly away from the sample; in this way, the atoms are continuously lost from the surface of the sample to achieve a polishing effect.
The precision ion polishing system is a specific instrument designed for the preparation of transmission samples (transmission electron microscopy samples are thin slices of several microns in thickness and 3mm in diameter). To meet the working conditions of the equipment, it is necessary to pre-treat the SEM sample. You should first cut the sample into one-millimeter-thick slices and then use sandpaper to sand the sample. When sanding the surface of the sample, you need to choose the sandpaper from coarse to fine.
TEM samples are usually very small in size and you should stick the sample to a small hole in the middle of the carrier. The size of the sample for SEM observation is much larger than that of the transmission sample. To increase efficiency, you can put more than one sample at a time and fix it on the sample table with hot melt adhesive. Then, you should adjust the working parameters of voltage, argon ion flow, sample inclination, polishing time, etc. An increase in the working voltage and argon ion flow can lead to an increase in polishing efficiency. However, if these two parameters are set too high, the sample can be easily damaged.
Use of precision ion polishing system
Precision ion polishing system steps
A. Preparation for operation
a. Confirm the argon content in the argon cylinder; the output pressure should be 25PSI.
b. Turn off the left and right argon-ion guns; raise the carrier table, the instrument vacuum should reach 5E-4 Pa.
c. Verify that the left and right ion guns (ion beams) are centered.
B. Exchange trial film
a. The test piece is held in place with the test holder and moved toward the center of the area to be reduced.
b. Raise the carrier table and remove the top cover of the pre-pumping chamber.
c. Place the sample holder of the pre-sampling chamber into the test holder and cover the top cover of the pre-sampling chamber.
d. Lower the carrier table and wait for the indicator (please refer to the product manual for specific color changes).
a. Set the polishing time.
b. Set operating voltage (usually set to 4Kev or 5 Kev).
c. Set ion gun
operating mode (usually set to dual ion beam modulation).
d. Adjust the left and right ion gun working angle (usually ±4 degrees).
e. Adjust argon working mode to Autogas mode.
f. Set carrier speed (usually 3RPM).
g. Start working mode.
h. Observe sample polishing during work.
i. After the sample is perforated, you can adjust to the low voltage and continue polishing until the thin area reaches the production requirement.
Precision ion polishing system precautions
A. Daily use
There is no need to turn off the instrument after daily use.
B. Power outage causes machine shutdown
a. Confirm whether the argon cylinder is closed tightly.
b. Turn off the main power.
C. Powering on after an error shutdown
a. Open the argon gas cylinder.
b. Turn on the main power.
c. Blow the ion gun to remove moisture from the surface of the ion gun to prevent the ion gun from becoming unstable due to air pollution. When the room pressure is lower than 5-3 EPA, open both air valve switches and purge for 15 minutes. The ion gun can be stopped when the beam current value is between 5 KeV and 8 μA.
d. It is necessary to wait until the vacuum level reaches 5-4ePa before normal operation.
e. When the ion gun is removed and reassembled, you should readjust the position to meet the operational requirements.
Precision ion polishing system technical specifications
a. Tilt range of sample stage: -120 to 210 degrees, the accuracy of 0.1 degrees.
b. SEM flat grinding table: max. φ25 mm × 12 mm.
c. TEM and FIB sample table: φ3mm.
d. Remote control can be achieved by setting the threshold value for termination of processing light transmission.
e. It should be ensured that the refrigeration system keeps the temperature of the sample preparation process within 25 degrees Celsius.
f. Independent double argon ion source, tilted ±45 degrees.
g. Capable of thinning single and double sides at small angles within a range of 10 degrees.
h. Capable of large-area ion polishing or thinning.
i. Particle energy: 800 volts - 10 kV adjustable, compensation 0.1 kV.
j. Ion beam current: up to 4.5 milliamps.
k. Time of sample changing within 3 minutes.
l. Equipped with optical microscope observation system.
m. Liquid nitrogen cooler and electronic temperature display.
n. Cooling time within 30 minutes and temperature can be set freely.
o. Precision ion polishing system equipped with an anti-contamination device to protect the cleanliness of the sample chamber.
p. Automated computer control with built-in reference parameters.
q. Oil-free vacuum systems with super silent molecular pump and oil-free mechanical pump two-stage system.
Precision ion polishing system applications
As mentioned, precision ion polishing system is widely used in transmission electron microscopy (TEM) sample preparation, and it is often used for the final polishing of samples that have been mechanically thinned. It is also widely used to clean the sample surface from damaged layers, amorphous layers, contaminants, etc.
The basic principle of ion thinning is the use of Ar ions. Ar ions are used to bombard the sample with different voltages and currents to achieve the effect of sample thinning. For ion thinning instruments, the operating voltage is usually in the range of several kV and the operating current is usually in the range of several mA, which is depending on the requirements.
How to buy precision ion polishing system?
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