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Hitachi SEM

Operating Instructions

Preparing a Sample

Before any work may be done with the SEM one must first properly mount the sample for viewing.
A single sample mount is available at the SEM station for general public use. If you require special characteristics (slope, etc.), or desire your own mount, it is your responsibility to have a machine shop prepare one that has the correct dimensions to fit the holder (see manual).
The sample's dimensions should not exceed 150 mm in diameter.
If your sample is non-conductive you will need to sputter gold onto the sample for proper viewing.
The sample may be attached using either the silver paint provided on the table opposite the SEM or with carbon tape. At this time the user must supply the latter. If the silver paint is used, apply a sample dab of the paint to the mount and adhere your sample to the mount (just enough to allow good adhesion, do not go crazy with it). Allow approximately five minutes for the full drying of the paint before placing the sample in the SEM chamber to ensure no paint is pulled into the vacuum lines.
When you sample is properly attached to the mount use the height-restriction marker to ensure that your sample is short enough to clear the SEM's working parts. If your sample is too tall and you attempt to place it into the chamber, you will damage the machine! Keep in mind that if your sample is relatively large and you plan on tilting it the tallest point on the sample will shift will be along the edge. You should adjust the z-axis appropriately to ensure the clearance before you tilt the sample.

Venting

Anytime the chamber is opened or pumped down one must ensure that the sample holder is in the exchange position. The exchange position settings for the four axes are listed on the side of the chamber. Moving the sample holder into or out of the chamber when it is not in the exchange position may damage the machine!

Once the exchange position is set, check the SEM software to make sure that no voltage is applied to the filament. If there is a voltage applied, turn it off by clicking on the HV button.
Press the EVAC button on the front of the SEM to begin venting.
You will see the pressure gauge on the screen move from blue to red as the pressure increases in the chamber. Once the gauge's bar disappears, allow approximately 30 more seconds before attempting to open the chamber.
Gently open the chamber. You should have to apply very little if any force to open the chamber if it is at atmospheric pressure.

Loading the sample holder

With the sample properly mounted and the chamber vented, the mount may now be placed into the holder.

The mount should slide easily into the holder's orifice. If there is resistance check that there is no obstruction inside the orifice or debris on the mount's walls. If it still does not slide easily ask for help from an experienced user or contact the equipment trainer.
While watching the tallest point of the sample to ensure clearance of the SEM's internal workings, slowly slide the chamber closed.

Pumping

While holding the chamber door closed, press the EVAC button to begin pumping the chamber.

The pump will engage and seal the chamber door.
The progress of the pumping may be seen on the on-screen pressure gauge. While the chamber is pumping the gauge will be red to indicate the incomplete vacuum in the chamber. The bar will then become green when the chamber is pumped and is being prepared for use. When the bar becomes blue the system is ready for use.

Viewing a sample

With the chamber pumped to operating pressure one may now prepare to apply an accelerating voltage to the filament.

The accelerating voltage may be set by right-clicking on the voltage display. See the manual for the particulars of choosing the best voltage for your purposes. Approximately 10-15 kV is a good starting point if you are unsure of what voltage would be best.
Click the HV button to apply the voltage and begin viewing your sample. If no current is displayed when a voltage is applied the filament is burned out and will need replacement. Please contact the trainer so that the proper steps can be taken.
With the voltage applied you are now ready to view the sample. You may adjust the position of your sample with the sample holder adjustment dials on the front of the chamber. The focus and zoom may be controlled from the small panel in front of the screen. The SEM software is also available to make fine adjustments of viewing parameters (please see the manual for details).
When you are finished viewing a sample follow the venting procedure, remove your sample and mount, and then follow the pumping procedure to prepare the chamber for the next user.

Taking a Digital Picture

With the sample focused and ready for capturing, click the PCI button on the top of the screen. The image on the screen will be captured and moved to the PCI image software.
To save the picture click on file and save as. You may now specify the file name and the image file type. This will create three files on the grover server which may then be downloaded from the cleanroom's equipment data page http://grover.mirc.gatech.edu/sem/
The three files will be the following:
name.pci = image for use in the PCI software
name.txt = text file listing the SEM's operating parameters
name.*** = image of the type you requested when saving (.jpg, .bmp, etc.)
A physical picture of your image may also be taken with the hardware provided. You must provide the film and the instructions are listed in the manual. Please contact the trainer if additional instruction is required.
The PCI software allows image manipulation and measurement among other capabilities. For the full instructions on these features please refer to the manual.

Troubleshooting

Q: What is the maximum size sample I can put in the SEM?

The chamber can handle up to a 4 inch wafer (200 mm). At minimum magnification the viewing area is limited to approximately 1mm by 2mm. Please see the instructions for details on working with large samples and maintaining safe working distances.

Q: I put my sample in but I can't see anything, its all black.

A: Adjust the brightness and contrast levels or use the auto brightness control.

Q: I put my sample in but I can't see anything, its all fuzzy.

Check to see if the magnification is at an extreme level. Adjust focus.

Q: When I find my feature it seems like no matter how much I adjust the focus I can't get a sharp image.

A: Check the stigmation. Often students make drastic changes to the stigmation and either forget to change it back or don't know how to change it back. The value should be somewhere in the neighborhood of x=50, y=50. If you still aren't able to get a good image contact Shawn to check the alignment of the system (DO NOT ATTEMPT TO DO IT YOURSELF!).

My image seems strangely rotated or tilted although my sample should be flat.

A: Check the raster tilt and rotation adjustments and make sure they are off.

I applied an accelerating voltage but I don't see an image and the current is at 0.

A: The filament has burned out. Please notify Shawn and he will pass the word along.

Can I use the instructions during my checkout?

A: By all means! In fact, keep a copy of the instructions with you at all times you use the SEM as a reference. There should always be a copy on the SEM itself, but if there isn't print out you own copy.

Where is the button for...(stigmation, focus, rotation, etc...)

A: You clearly haven't read the instructions nor did you listen during the instruction session. Please sign up for an additional training session.