Refer to the Material and Process Compatibility page for information on materials compatible with this tool.
Equipment Status
: Set as UP, PROBLEM, or DOWN, and report the issue date (MM/DD) and a brief description. Italicized fields will be filled in by BNC Staff in response to issues. See Problem Reporting Guide for more info.

Issue Date and Description

Estimated Fix Date and Comment

Responding Staff


iLab Name: Alpha-Step
iLab Kiosk: BRK Metrology Core
Owner: Rich Harlan
Location: Cleanroom - M Bay
Maximum Wafer Size: 6" / 150 mm


General Description

The KLA-Tencor Alpha-Step IQ profiler measures step height, waviness and roughness of a surface.


Accommodates up to 150mm (6") substrate and 21mm (0.83") thick. Measurement of vertical features ranging from 100 nm to approximately 0.4 mm. Lateral feature detection is limited by the 5 μm stylus radius.

Sample Requirements and Preparation

There are no real requirements, but keep in mind that flexible substrates may experience slight deformation under the 20 mg of force applied by the stylus tip.

Standard Operating Procedure

Training / Video SOP

Written SOP

 Standard Operating Procedure

This instruction covers the set-up and safe use of the Alpha-Step IQ Profiler measurement system. This tool is a high-sensitivity surface profiler that measures roughness, waviness and step height. The measurement stylus is very fragile and should not be subjected to soft, tacky samples.

  1. Safety Requirements

    1. Safety glasses must be worn whenever in the cleanroom, except when using a microscope or when wearing protective goggles.

    2. Do not place hands near the measurement scanner assembly – hand/fingers may be trapped during stage movement

    3. Do Not place or move any object near the stylus area or on the measurement area cover as this may damage the fragile stylus and cause extended downtime

  2. Equipment

    1. KLA-Tencor Alpha-Step IQ (ASIQ)

    2. KLA-Tencor AS-IQ Measurement Tool

    3. Computer, user interface, keyboard and mouse

    4. 6-inch Rotary table on the measurement stage

    5. Camera Monitor

  3. Tool Configuration



    Figure 1.

    Figure 2.

    Figure 3.

    Figure 4.

    Figure 5.

    Figure 6.

  4. Cycle of Operation

    1. User time must be scheduled through iLab prior to using the system.

    2. Ensure the stylus is in the high position before loading the sample. This is done by double-clicking the "Up" arrow seen on the control panel (Figure 4). When the stylus is in high position the "Stop" button will switch from red to grey.
    3. Open the front Plexiglas panel on the front cover, allowing access to the measurement area. (Figure 1)
    4. Place the sample on the X-Y stage and, using tweezers, the sample should rest on the front half of the rotary table. (Figure 2)
    5. Rotate the sample stage until it is under the measurement area.
    6. Close the front Plexiglas panel on the front cover
    7. Use the X-stage and Y-stage control knobs to move the sample under the "V" marks on the measurement area cover. The X/Y control knobs are located on the left side of the tool.
    8. Verify the sample is aligned and under the two "V" marks on the measurement area cover
    9. Select the correct recipe by pressing the "Load…" button
      1. Select/highlight the desired recipe from the recipe window
      2. Left click on OK to select the recipe
    10. Double click the down button
    11. Click the up button once
    12. Align the area of interest, such as a vertical step, in the center of the camera monitor (Figure6) in line with the stylus horizontal scan path.
    13. Press the "Start" button. The stylus will lower and scan across the area of interest.
    14. Wait for the scan to end or press the red "Stop" button if it is necessary to abort the scan.
    15. Verify the "Step Height Analysis" is displayed in the Analysis window. If not, select this from the Analysis dropdown window
    16. Press the Leveling button shown in Figure4
    17. Select the 2 bars or 2 zones depending on your preference
    18. Please the cursor over the "L" or "R" before Left clicking and holding to position the bar(s). Both the "L" and the "R" bars must be on the same plane for the leveling to work correctly.
    19. Left click on the desired operation, usually "Level using 2 bars", before clicking on "OK"
    20. Select the desired step height evaluation, usually 2 bars or 2 zones, and position the "L" and "R" cursors on the step to be measured.
    21. The height difference between the "L" and "R" bars is displayed next to "Height" to the left of the graphical scan, shown in Figure 4.
    22. Double click the up button after all measurements have been completed
    23. Move the stage out away from the measurement area using the Y-stage control knob
    24. Open the front Plexiglas panel on the front cover, allowing access to the measurement area. (Figure 1)
    25. Remove the sample from the X-Y stage rotary table using tweezers. (Figure 2)
    26. Close the front Plexiglas panel on the front cover.
    27. Log out of iLab

  5. Supplemental Data

    1. Performance Specifications

      1. Measurement of vertical features ranging from under 100Å to approximately 400um (0.4mm) with a resolution of 0.24Å

      2. The maximum horizontal surface scan length is 10cm (when scanning left-to-right)

      3. The minimum spacing between features to be measured must be > 0.01 μm due to the radius of the stylus

      4. The stage can handle samples up to 150mm (6-inches) wide and 21mm (0.83-inches) thick

    2. Definitions

      1. Scan Length (mm) is the length of the horizontal scan across the sample

      2. Number of Scans: is the value that defines how many scans will occur before displaying the mean and standard deviation (when greater than 1)

      3. Scan Speed (um/sec); is how fast the stylus will travel across the sample, values between 2 and 200

      4. Sampling Rate (Hz); is the number of samples taken per second, values between 50 and 1000

      5. Scan Time (s); this is the product of the scan speed, sampling rate and number of scans

      6. Scan Direction (←→); this value should always be Left-to-Right →

      7. Resolution (μm); this is defined by the scan speed and the sampling rate

      8. Sensor Range (μm, mm); select the range defined by the sample vertical step, if unsure select 2 mm

      9. Adjustment; defines the starting point for the sensor range

      10. Contact Speed; the speed at which the stylus approaches the sample

      11. Required Radius; is a fixed value of 5m based on the stylus and should not be adjusted

  6. Startup and Shutdown

    1. Startup

      1. Turn on the computer is it's not already powered up. The KLA-Tencor logon screen will automatically be displayed. The measurement stage will also initialize during this period.

      2. Select the username, student, from the dropdown window

      3. Type "research" in the password window before clicking on "Enter"

      4. Select the desired recipe as described in Section 4, Cycle of Operation

    2. Shutdown

      1. Left click on the "Exit" button at the top of the Alpha-Step window. See Figure 4

      2. The software will close and shutdown Windows as well as the computer.


Questions & Troubleshooting

What's the difference between fast scan speeds and slow scan speeds?
Fast scan speeds take less time, but at the cost of horizontal resolution and roughness data. Under extreme circumstances it can also cause the stylus to skip.

What's the difference between scanning left to right and right to left?
While the tool is capable of measuring right to left, it's designed to go left to right. That's the method that wears the least on the machine.