Field Emission - Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray (EDX) (Ishikawadai 1, 6th floor) By: Willy Kurnia Note: In order to reserve the equipment, please go to the Workshop’s website and make the reservation online. The contact person is Iiyama-san (email@example.com). EDX cylinder SEM monitoring panel SEM chamber Main controller Fig. 1 FE-SEM equipment Sample preparation: 1. Clean your specimens using ultrasonic cleaner. 2. For nonconductive specimen, coating is necessary. Use the carbon coater for this purpose (the carbon coater is inside the same room with SEM equipment). 3. Mount the specimen onto the specimen holder (see Fig. 2). Make sure that the specimen size is smaller then the specimen holder size (approximately 25 mm in diameter). Always wear a glove when you handle the specimen. (a) Plunger (b) Specimen holder Fig. 2 Plunger Specimen holder Equipment preparation: 1. Close the chamber valve (bellow the SEM chamber) by pressing the “V7G” button. 2. Wear the plastic glove and mount the specimen holder to the plunger by inserting the plunger rod to the thread hole on the specimen holder. You can only touch the specimen holder, plunger thruster, and plunger disk with your hand. Never touch other parts, even with the glove!!! Fig. 3 Inserting the plunger rod in to the SEM chamber 3. Open the vacuum chamber cover and insert the plunger and specimen holder. Make sure that the plunger disk fit perfectly with the vacuum chamber cylinder. 4. Hold the plunger disc with your left hand and use your right hand to evacuate the SEM chamber by pressing the “evac” button. The light on the “evac” button will torn on when you press it. Wait until the light off. 5. Since the SEM machine is quite old, you need to evacuate the SEM chamber three times. However, the second and third times are quite different from the first one. After the “evac” button has been turned off, press the “evac” button again. Wait until approx. two seconds, and then press the “evac” button one more time. Now, wait until the lamp turns off and do the same procedures one more time. 6. Open the SEM chamber lid by turning the handle 90o (ccw) and pull it to the right. 7. Insert the specimen holder to the SEM chamber and mount it to the slider inside the chamber. Unlock the plunger by rotating the thruster counter clockwise (ccw). After that, pull the plunger out from the SEM inside chamber. 8. Close the SEM chamber lid by pushing the handle to the left and turning the handle 90o (cw). 9. Vacuum the SEM chamber holding the plunger disk with your left hand and press the “evac” button with your right hand. Do the same procedures as when you evacuate the SEM chamber before. You also have to do this three times. 10. Take out the plunger and keep it on the plunger holder. Close the chamber using the vacuum chamber cover. SEM: (a) SEM monitoring panel Acc. Voltage button Acc. Voltage knob Gun Alignment Y Emission current knob Gun Alignment X Emission current reset button Flash (b) Main panel Probe current Contrast & Brightness Focus Magnification (c) Controller Fig. 3 SEM control panel 1. Turn on the two monitors on the SEM panel. 2. Make sure that the “accel” ready lamp is on. 3. Push the “manual flash” button for 1 second (weak flash). Please wait until the current (shown on the monitor) increases to 12 A. 4. Increase the acceleration voltage slowly to 10 kV or more, correspond to the specimen’s material. The “accel” voltage knob is a ratchet. Make sure that you increase the voltage real slowly. One click at a time!!! 5. Set the CL course from four to one. For each CL course, set the gun alignment (left and right) until you see the brightest image on the monitor. Do this for the four CL course settings. 6. Set the focus and stigma. Use any particular point on the workpiece and zoom into it. Adjust the focus (“course” focus continued with “fine” focus) while zooming. You can see the image on the monitor to judge whether you have already set the focus right or not. Once you do, increase the magnification larger than 2500x to set the X and Y stigma. Adjust both of the stigmas to get the sharp image. After that, adjust the focus again and continued with the stigma. Do this over and over again until you get the sharpest image. 7. Check the current, if the current is much lower than the initial value (12 A), reset the current. 8. You are now ready to do the analysis using SEM. Capture the image that you need using the camera (see Fig. 4). Remember, since the specimen might not be flat, the focus might change from one location to other. Always remember to check the image focus and adjust it accordingly when it changed. Fig. 4 Camera for the FE-SEM equipment EDX: How to take the picture? i. Inserts the Smart Media card into the card slot on the camera ii. Turn on the camera. The camera light will starts blinking iii. Push the display button on the camera twice to show the picture on the SEM panel iv. Set the camera focus at the brightest point v. Press the `left` button vi. Use the panel (remote) and press the `lock` up then press the button vii. Wait until all parts of the picture are saved into the Smart Media card, and then push the `lock` button down again. viii. Take out the Smart Media card after all the pictures have been taken. (a) Liquid nitrogen cylinder (b) Computer for the EDX analysis Fig. 5 Energy Dispersive X-Ray 1. Once you finished with the SEM analysis, you can continue with the EDX analysis. First, close the chamber valve by pressing “V7G” button. The button is under the SEM chamber. 2. Before you proceed any further, make sure that the working distance (WD) is exactly at 15 mm and the focus is set at this WD. You can do it by moving the specimen vertically to 15 mm and adjust the focus. Since adjusting the focus is also means changing the WD, you have to do this a few time until you get the right setting. 3. Turn off the monitor and reset the current if you need to (current << 12 A). 4. Check the volume of the liquid nitrogen on the cylinder. Refill the liquid using new liquid nitrogen. Take extra care during this process. Use protector!!! Liquid nitrogen is a dangerous substance, it can freeze your body in a jiffy and you’re nothing but history!!! 5. Turn the screw below the liquid nitrogen cylinder until maximum. 6. Turn on the FE-Gun box power (on the right side of the SEM panel) and set it to 8 A. 7. Turn on the database computer for EDX analysis. 8. Open Link ISIS software and login by choosing “oxford”. 9. Starts the EDX analysis. (Please refer to Iiyama-san for more details on this software). Finishing stage: 1. 2. 3. 4. 5. 6. 7. 8. 9. Reset the current to 12 A. Turn off the monitor on the SEM panel. Turn off the database computer. Turn off the acceleration voltage and decrease the value to zero. Return the screw under the liquid nitrogen cylinder to its initial position. Return the specimen holder inside the SEM chamber to its initial position. Take out the specimen (the procedure is similar with “equipment preparation”. Make sure that all the equipment and tools are returned to its place. Fill in the form on how many time did you do manual flash.