Scanning Electron Microscope Instructions

Safety Precautions

Please log into the Notebook when you load your sample and log out when you leave.

Make sure that FRED is not being used before loading your specimen.

Always shut valves 1 and 2 before turning on Turbo Pump.

Never operate Ion Getter Pump above 20 mA for more than 2 minutes.

Never operate Ion Getter Pump above 250 microamps with the filament on.

Introduction
Pumping Down
Getting An Image
Improving Your Image
Saturating the Filament
Saving Your Image
Changing Specimens
Long-Term Shutdown
Before You Leave
Glossary

Introduction

Pumping Down

• Water, N₂, Air
• Power Strip
• Mains Switch on
• RP On

• Close #1
• Front Panel On
• Press Pumping Unit (TP)
• HV On

• Turn IGP MAINS on
• Switch both white switches up
• Switch to Pump
• Must be below 20 mA within 2 min

• Switch to Run (Knob and Switch)

Getting an Image

Improving Your Image

• As you magnify the image, use a smaller spot size. Adjust the Gain and Black Levels appropriately

• Press the auto focus search button. The image will disappear and reappear in few seconds.
• If the image is still the same, press the auto focus fine button.

• The Manual Focus is located below the Auto Focus. The inner knob sets the step size, and the outer knob adjusts the focus. To fine tune the focusing knob, adjust the inner knob counterclockwise.

Saturating the Filament

Saving Your Image

Changing Specimens

• Close #1
• Press Pumping Unit (TP)
• HV On

• Switch both white switches up
• Turn IGP MAINS on
• Switch to Pump
• Must be below 20 mA within 2 min (If not, turn back to start and let the IGP cool down for 10 min)

• Switch to Run (Knob and Switch)

Long-Term Shutdown

Before You Leave

• Are the High Tension and Bias Control turned off?
• Is the Filament Knob turned fully counterclockwise?
• Is the IGP off or operating at a safe current?
• Are the knobs on the N₂ bottle closed?
• Did you log out of the Notebook?

Glossary

Auto Focus

The Auto Focus controls are located toward the central lower right of the Front Panel. The Search Button triggers the Auto-focus mechanism, and the Fine Button fine tunes it. Below these buttons is a knob for manual focus. The inner knob sets the set size, and the outer knob adjusts the focus. The lights on either side will illuminate when the focusing mechanism is out of range. The Auto Stigmator Button is located at the top.

Beam Control

The Beam Control Unit is located near the lower left corner of the front panel. The gauge at the top measures the filament emission in microamps. Below that is the filament knob. The inner knob adjusts the current flowing through the filament. The Gun Tilt and Shift knobs are located below the filament knob. They are used to allign the beam. Improper adjustment can cause poor or no images to be displayed. At the bottom is the Spotsize Knob. Generally, keep this at 7. 8 produces no spot.

Compressed Air

The Compressed Air is located on the wall next to the door. It is used to operate the pneumatic valves. To turn on the Air, open the blue valve closest to the door. The other valve vents the air to the room.

Computer

The computer sits on top of the microscope. It is used to save the pictures from the SEM.

Detector Control

The Detector Control Unit is located in the lower right corner of the front panel. The knob at the top is the Bias Voltage Knob. Keep this adjusted fully clockwise. Below that is the On Button. It should illuminate when depressed. The Gain and Black Level Knobs are used to adjust the quality of the image. These need to be readjusted whenever the magnifaction is changed.

High Tension

The High Tension controls are located in the lower left end of the front panel. The top two knobs are used to set the volatge. Leave this at 30.0 kV. Below these two knobs is the On button. When the button is depressed, the light should be on. If the light does not turn on, try pushing it several more times. The light needs to be on for the filament to emit.

High Vacuum (HV)

The High Vacuum controls are located on the lower right corner of the front panel. The ON-Off controls at the top of the HV panel turns on the Pirani gauge, which is measured by the analog dial on the HV. The lights on these buttons are wired backwards - i.e. the gauge is on when the off light is on, and the gauge is off when the on light is on. The light next to the Pirani turns on when the pressure is too high for the IGP to be turned on. The IGP is interlocked with the HV, and will not properly work unless the HV light is out. At the bottom of the HV is the On-Off switch for the Front Panel.

Ion Gauge (IG)

The Ion Gauge is connected to the TP. The display for the gauge is located on top of the SEM and is labeled IG. It automatically comes on when TC1 is low enough. To turn the gauge off, press the EMIS button. The numbers are displayed in significant figures and Torr. (2.0 -1 = 200 mTorr)

Ion Getter Pump (IGP)

The pumping unit is located on the side of the column. The controls for the IGP are behind the chair on the opposite wall. The pressure gauge for the IGP is located on the control unit and is measured in microamps. The controls on the IGP include two white switches and a knob that has three positions - start, pump, and run. The lights above this switch signal if the proper vacuum conditions have been met to start the IGP. The power switch for the IGP is labeled Mains, and controls the valves that open the upper column to the rest of the system. The gauge on the IGP has a knob underneath it to adjust the scale. Setting the knob to 25 mA sets the maximum reading at that scale to 25 mA, etc. Under no circumstances should the IGP be run over 20 mA for more than 2 minutes. If you immediately receive a reading of less than 50 microamps, the IGP is not working. DO NOT TURN THE FILAMENT ON. The IGP will typically run between 50 and 100 microamps. The filament should not be turned on above 250 microamps.

Magnification

The Magnification Control is located in the lower center of the front panel. The lower knob is used to set the range of magnification. The button is used to turn the Zoom feature on and off. WHne the zoom feature is on, the upper knob zooms in 8x the basic magnification level. The LED displays the current magnification level in standard sceintific notation.

Mains switch

The Mains switch turns on the power to the SEM and is located behind the SEM next to the fuses.

Nitrogen gas (N₂)

The Nitrogen gas is located in the orange bottle on the wall. It has two valves on the top of the bottle which must both be opened. The pressure should read around 0.5 atm. Use the center knob to adjust the flow. The N₂ is let into the SEM through two valves, labeled #1 and #2 and located on the copper tubing on the left side of the SEM. The N₂ is used to backfill the SEM to prevent oil vapor from entering through the pump, so it is extremely important to open these valves before the RP is turned off.

Notebook

The Notebook is used to keep track of the users of the SEM. When you load your sample, please record in the notebook that you have a sample loaded. If you've removed your sample, please note this also. Also, record any problems you experience with the system, strange noises, etc.

Power Strip

The power strip is located behind the SEM. It controls the computer and the black gauge.

Roughing Pump (RP)

The Roughing Pump is located in the hallway. It is controlled by a toggle switch on the left side of the SEM desk. The RP should be on during all phases of SEM operation, and is only turned off when changing specimens.

Scan Mode

The Scan Generator is located in the lower center of the front panel. Generally, you will only use the row of buttons marked Scan Mode. This should be set to TV.

Specimen Door

The Specimen Door is located on the front of the column. The door is locked into placed by the force of the vacuum.

Thermocouple Gauge (TC1)

The Thermocouple gauge is located is the side of the Turbo Pump. The display for the Thermocouple is located on top of the SEM and is labeled TC1. The numbers are displayed in significant figures and Torr. (2.0 -1 = 200 mTorr)

Turbo Pump (TP)

The turbo pump unit is located below the column. The controls for the TP are in the upper right corner of the main panel. The TP should be operated only when TC1 is less than 200 mTorr (2.0 -1)

Water

The water is located on the wall next to the N₂ bottle. To turn on the water, both blue spigots must be opened. The water is used to cool the TP.