Page 1 of 5 NRF Dektak II SOP The Dektak II-A is a sensitive stylus profilometer. A diamond-tipped stylus is moved laterally across the surface while in contact and measures deflections of the tip. It can be used to measure step heights (film thickness) and surface roughness. The vertical measuring range is 50Å to 65µm and can perform a line scan as long as 30mm. Prerequisites for operating the Dektak II: a) Receive one on one training and certification from NRF Staff. Discuss your process with a staff member. b) Obtain a NRF ID (if you do not already have one) by completing the NRF Lab Use Request Form. Safety High Voltage - Voltages supplied to and within certain areas of the system are potentially dangerous and can cause injury to personnel. 1.0 Pre-Operation 1.1 Tool Reservations may be made via the NRF Reservation Page. http://nimet.ufl.edu/servicecenter/resources/default.asp
Page 2 of 5 2.0 Operation 2.1 START UP 2.1.1. Turn on the unit by pressing the switch located on the back. The documentation included with the DekTak tool states that the tool makes the most accurate measurements 15 minutes after having been turned on. Turn on the unit before logging into TUMI and allow it to warm up! 2.1.2. If you do not see anything on the main monitor, press the VIDEO key under DISPLAY/STYLUS to switch on the text screen of the main monitor. 2.2 SAMPLE LOADING 2.2.1. Move the stage forward along the Y-axis, by turning the right thumbwheel clockwise, until your sample can be placed near the center of the stage. 2.2.2. Use the X and Y thumbwheels to move the stage until the sample is positioned below the stylus. 2.2.3. Press the key under DISPLAY/STYLUS to lower the stylus. The monitor displays the image from the mounted video camera. Turn the focus knob such that the stylus tip and its reflection are sharp and centered on the screen. DO NOT move the stage by a large amount while the stylus is lowered. 2.2.4. Press the key under DISPLAY/STYLUS to raise the stylus. Locate the general area of measurement. Refocus the sample, if necessary.
Page 3 of 5 2.2.5. Lower the stylus again, and use the thumbwheels to CAREFULLY move the feature to be measured to the right of the stylus tip. The scan direction is to the right. CAUTION: Keep the stylus RETRACTED while moving the sample over long distances. Lower the stylus only when making fine adjustments to find the scan's exactstarting point. 2.2.6. Raise the stylus by pressing the key. The instrument is now ready to make a scan. 2.3 Set/Check Scan Parameters 2.3.1. Press the PROG key under SET-UP on the keyboard. 2.3.2. Program the appropriate scan length, speed, range, and profile. Use the arrow keys under DIRECTION on the keyboard and the numerical keys to change the parameters. Press ENTER whenever making changes. Select NO for Auto Leveling. 2.3.3. Scan Program. Up to ten programs can be stored in the machine for quick loading of often-used parameters. 2.3.4. Scan Length. Scan lengths are available from 50 µm to 30 mm. 2.3.5. Speed. Three scan speeds are available: Low, Medium, and High. Low speed provides high horizontal resolution measurements (i.e., generates more data points). High speed saves time, but offers lower resolution. Medium speed is most commonly used. 2.3.6. Range. This parameter provides a choice between the Auto Ranging feature and a user determined display range. The maximum display range is 655 kå. Selecting an Auto Ranging feature automatically ranges the profile to fill 80% of the display. 2.3.7. Profile. Three different profiles are available, depending upon the sample surface characteristics and the measurement range to be selected. 2.3.7.1. Valleys - Provides 90% of the Measurement Range below the zero horizontal grid line. 2.3.7.2. Hills and Valleys - Provides 50% of the Measurement Range above the zero horizontal grid line and 50% below. 2.3.7.3. Hills - Provides 90% of the Measurement Range above the zero horizontal grid line.
Page 4 of 5 2.3.8. Auto Leveling. This is used to automatically level a scan where two scan reference points lie on the same plane. Always set to NO. 2.3.9. Reference Cursor. This sets the horizontal position of the reference cursor and is very useful for measurements on multiple, identical samples or multiple identical measurement locations on the same sample. The cursor position can be moved later as necessary, so it is not critical to position it at this time. 2.3.10. Measurement Cursor. This sets the horizontal position for the measurement cursor in an identical manner. 2.4 SCAN SAMPLE 2.4.1. Make sure your scan parameters are correct, and press the SCAN key under SET-UP to initiate the scan. On the main monitor, you can see a surface profile trace being generated (vertical vs. horizontal distance on a large scale). When the scan is finished, the plot will be redrawn according to the program settings. 2.4.2. If the trace is at an extreme slope, manual coarse leveling (see section 6.5) is necessary to obtain accurate results. 2.4.3. Level the trace if coarse leveling is not required. 2.4.3.1. Position the R (Reference) and M (Measuring) cursors on two points that should be of equal height along the sloping line. Press the keys labeled R and M under CURSOR to select a cursor. The selected cursor is shown on the lower-right corner of the main monitor. Use the left and right arrow keys under DIRECTION to move the cursors. Holding down the FAST key while moving the cursors makes them travel faster. 2.4.3.2. Press the LEVEL key under CONTROL and the profile will be redrawn with the points leveled. 2.4.4. Once the trace is level, position the R (Reference) cursor at the base of the step and the M (Measuring) cursor at the top of the step to measure the step height. Press the keys labeled R and M under CURSOR to select a cursor. The selected cursor is displayed on the lower-right corner of the main monitor. Use the left and right arrow keys under DIRECTION to move the cursors. Holding down the FAST key while moving the cursors makes them travel faster. 2.4.5. The absolute height at each cursor is shown on the screen by R CUR and MCUR, and is followed by the horizontal distance from the starting scan point. VERT shows the vertical distance between the
Page 5 of 5 height values at the R and M cursors. HORIZ shows the horizontal distance between the two cursors. 2.5 UNLOAD SAMPLE 2.5.1. Making sure the stylus is retracted, move the sample stage outward using the Y thumbwheel until the sample is clear from under the stylus. 2.5.2. Remove the sample with tweezers and load the next sample if applicable. 2.5.3. Turn off the power. 2.6 COARSE MANUAL LEVELING 2.6.1. Using either your own sample or a flat wafer, locate an area of the surface that is known to be level, and position it for measuring. See section 2.2 for help with sample positioning. 2.6.2. Press the SCAN key under SET-UP. 2.6.3. As the stage is moving and a trace is being generated on the screen, turn the leveling thumbwheel (shown in Fig. 1.) until the profile trace is tracking in a horizontal line. Clockwise rotation raises the trace and counterclockwise lowers the trace. 2.6.4. Press SCAN again. The profile must appear completely within the graphic boundaries (with Range set to Auto in the program menu) to achieve the minimum acceptable manual leveling. If not, repeat the manual leveling procedure above. 2.6.5. Once the stage is level, proceed to step 2.2 to measure or remeasure your sample. NOTE: You may want to adjust the Range parameter in the program menu to a smaller scale for finer leveling.