Equipment Descript:
The scanning electron microscope (SEM) uses a focused beam of high-energy electrons to generate a variety of signals at the surface of solid specimens. The signals that derive from electron-sample interactions reveal information about the sample including external morphology (texture), chemical composition, and crystalline structure and orientation of materials making up the sample.
In most applications, data are collected over a selected area of the surface of the sample, and a 2-dimensional image is generated that displays spatial variations in these properties. Areas ranging from approximately 1 cm to 5 microns in width can be imaged in a scanning mode using conventional SEM techniques (magnification ranging
from 5X to approximately 30,000X, spatial resolution of 50 to 100 nm). The SEM is also capable of performing analyses of selected point locations on the sample; this approach is especially useful in qualitatively or semi-quantitatively determining chemical compositions (using Energy Dispersive Spectrometer (EDS).
Scanning Electron Microscope 6490LA (SEM) Basic operation
Starting the Instrument:
Turn on the main power supply
Turn on the water chiller wait for 15 min then Turn the keys-witch to START
Wait for 10 second, switch on the personal computer
Start JOEL SEM Program wait until the evacuation completed and the EVC turn to green.
Sample Exchange:
Press the Vent Key (wait until the vent key stop from flashing).
Open the specimen chamber door and insert the sample.
Press EVAC key (wait until the EVAC key stop from flashing). The system now is ready for observation.
Gun Alignment:
Click the { Gun} icon the Gun alignment will appear
Turn ON the Emp ( emission pattern)
Open valve VT3
Turn [ON] the HT
Turn [OFF] the beam blanking
Set the spot size to [30], and set the Alignment – Tilt- Shift [X, Y] slide to near the center.
Press the per heat then drag the filament heating slider slowly to the right until you reached the saturation point
If the L.C value shows 20µA over or below the following value, adjust the L.C value by performing bias adjustment.
High Acc voltage (5.0-30kv): 60-80µA
Low Acc voltage (0.3-4.0 kv): 40-60µA
Turn [OFF] the Emp ( emission pattern) to bring the image into focus.
Energy Dispersive Spectrometer (EDS)
EDS Basic Operation
Liquid Nitrogen Filling Procedure
Note: Before you use the EDS you have to filling the mini-cup tank with Liquid Nitrogen, to do so,
please follow the following procedure:
- Confirm the “ Power” lights.
- Confirm the “EVAC” lights.
- Press the “ start “ at the Detector controller you will hear Beep after 15 minutes.
- “ EVAC” to lit continuously from blinking (Pour LN2 within 10 minutes)
- “COOL” to be lit continuously from blinking (Beep will stop) the system will be ready after 50 minutes approx.
Gun Alignment:
HT must be ready.
Switch on the HT.
Conduct a filament saturation (get the first and the second beaks).
Tilt Adjustment: set the spot size to 20 and below, adjust the tilt X, Y until you get the max brightness.
Shift adjustment: set the spot size50 and above, adjust the tilt X, Y until you get the max brightness.
Adjust stigmatisms and Wobblers (Wobblers should be carried out at high mag.5000 and above). EDS analysis:
Filling the liquid nitrogen tank with liquid nitrogen, make sure the EDS ready before start the analysis.
Performing EDS Analysis:
- Make sure that the WD is 10 mm and the KV at least 15 KV or higher.
- Get an image from the SEM and freeze it
- Send the image to the EDS, system will ask you to create and project no. for this take, Please does so.
- Set the analysis conditions (CPS should be between 1500-5000)-blue and green color are acceptable. If the CPS is not foiling in this range you need to adjust WD/SS and filament saturation.
General Information:
Right click on the mouse for course adjustment, Lift click on the mouse for fine adjustment.
If the specimen has different level, set up the aperture at No. 1.
To see two different images (SE-BE) at the same screen (center of the screen) click on Tool-Mulilive image- Flexible window image.
For higher resolution, you need to set the aperture at position no. 1.
The aperture should be set on position 2 or 3 for analysis purpose
Aperture sizes:
1-20 micron higher resolution
2-30 micron general purposes
3-100microm when you have difficulty in getting higher CPS, it is recommended to set the aperture at position 3.
WD is related to the KV.
Low Vacuum Mode:
After the evacuation completed, set up the pressure at 10 PA and click on start (you will find the low vacuum control key at the right side on the screen).
Note-1
If the sample gets charging, increase the pressure until you get red out the charging.
At low vacuum mode, if we conducted an analysis on low vacuum mode and noticed that the CPS is low (less than 1500 CPS) then you need to increase the spot size.
Increase the spot size, if the image becomes so dark and CPS is not increasing then adjusts the contrast and brightness using the course knob (backscatter). Then, adjust the gun alignment shift.
Recipe Icon: This is to save all conditions for certain project, after you are done with all
adjustments and freeze the photo. Press the Recipe icon and add the name for your sample press OK. Then, all condition will be saving for you, and you can come back again and use same condition for smaller samples.
If you missed one of the imaging icons from the main screen, go to the setup and select icon setup- select the missing icon and apply.(1)
Note-2
The accuracy of the EDS analysis is 0.01% for all elements except the light elements, so any element is greater than the 0.01% should be detected by the EDS.
The quantitative analysis results should show the mass % is greater than the error%, If the error % is greater than the mass % for certain element, that element is not exist.
VID (visual identification) technique used to determine the present of an element or not. Press the VID icon you will see two lines, one is yellow and the other one is black, the yellow is the back ground and the black is the compare generator spectrum , if the back ground is filling the black line profile, the element is exist.
If you want to add an element to the analysis list click on the “Ptbl” (Periodic table) icon and the element and press play which is located under tool.
To change the color of the mapping screen go Tool-Edit Element Palette –Rest –select Mono color –OK-Auto- Apply Now- OK.
To report mapping:
After saving the mapping data, click on OVER icon –select the element you want to be shown on the report and drag it to the right side of the screen-Press analysis- show spectra –Press Quantify – Previews- Export to word.
Measurements:
To do measurement, first you have to freeze the image-select image-select Texl/Scalerselect
ruler and do your measurements.
SRT (scan rotation)
If you want to rotate the live image-Press SRT icon and adjust the sliding bar between 180+180. (This icon is located at the top tool bar, if it not there you can add) see Note (1).
At any spectrum you can change the color, font, and lines of spectrum by clicking on the Tool-Setup.
To know the energy level of any elements go to the Predict table and select the element and Press Label icon at the same menu.
Multiview Sequential analysis:
The Multiview sequential analysis use to analyze different areas in sequins, if you want to conduct a sequential analysis first get images from all areas of inters, and send to the EDS. Press the SEQ (sequential analysis) icon- set the conditions at the SEQ window as shown below:
® ZAF ® Standard less ® Pure ® HT turn off HT when analysis finish.
Then Press Start and wait until the analysis completed.
Highlighted all images
On the analysis station window Press file-Page setup- Map/Thumbnail—OK.
Press File-Print Preview.
To remove JEOL Logo- Select Hand Icon- Right Click on the logo then Delete.
To report the data, highlights the EDS results-Right click-Show compare.
SIP Procedure:
- Switch on the machine.
- Open VT1 &VT3 and press EVAC.
- Before you turn on the SIP leave the system for 2 hours to be stabilized.
- After that close VT1&VT3 and wait until the SIP Lab become orange.
- Press SIP power and wait until the system reached 10-5Pa. When the Machine reaches 10 Pa-5, the system is ready.