Ambios XP200 Profiler

Purpose & Scope

The purpose of this document is to train the user with the most basic operation of the XP-200 profilometer. This limits the user to measuring steps on profiles with less than 100 µm step heights.
To use advanced features, the user must be trained with the Ambios Technology Manual, available to
users on special request only. 

Associated Documents & References

• Operator’s Manual for XP-Plus Series, Ambios Technology, October 2007
• Ambios Technology Inc. (http://www.ambiostech.com/)

Equipment Description

The Ambios XP-200 profilometer is located in the Etch/Dep room. This equipment is reserved through
the online resource scheduler. If you need technical support, check availability with personnel before reserving the equipment. Users have to go through training before using this equipment alone. 
 
If the sample can be measured via an optical method (such the Nanospec 210), it is preferable to do so as contactless measurements are inherently less intrusive and risky.

The XP-200 operation is driven through a proprietary Windows XP application running on a desktop computer, and  interfaced with  the user  through a CCD camera, a keyboard/mouse and a  flat panel display. The system is placed on an air-cushioned table to minimize vibrations. 
 
A  stylus  scans  the  sample  surface at a programmable  speed, while  its position  is  sampled at  small and  regular  intervals. The data  is  logged and  then processed by  the application software to extract useful information such as step height, surface roughness and waviness.

Summary of the system basic features: 

Summary of the system advanced features: 

* This feature requires additional hardware and is not available at present.

Pre-Measurement Verifications

Check list of important points to verify before processing

Profilometer Status

• The system is reserved and available for use.
• The XP-200 is turned-on for at least 20 min (on/off switch is above the power socket).
• The Computer is turned on for at least 10 seconds.
• The vibration isolation table is properly inflated: it bounces slowly if you press down on it lightly. If not, it is either under- or over-inflated. Call tech support to correct if necessary. 

Sample Status

• Materials:  Typical materials  go  from  Photoresist  (soft)  to  Silicon  Nitride  (hard). When measuring Photoresist make sure it has received the proper Post Exposure Bake so that its surface is not wet or tacky. Make sure the sample back-side will not leave residues on the stage. 
• Adequate  force & speed are  function of stylus and material. Too  low a  force may yield too much noise,  too high may damage  the  sample or underestimate a  step height. To minimize the risk of a scratch for a given force, be prepared to use the lowest force and speed necessary. 
• Expected  topography; steps exceeding 100 µm  require special precautions so as not  to damage the stylus; if your sample belongs to this category, or if there is even a small risk it does, see next section. 

Technical Assistance

• Technical  Assistance  is  required  for  basic  training,  advanced  training  or  the  use  of advanced features without advanced training. 

• Steps  exceeding 100 µm  require  special  precautions  to  prevent  stylus  damage;  if  your sample belongs  to  this  category, or  if  there  is even a  small  risk  it does, you will need technical assistance to perform the measurement, or advanced training with the Ambios Manual.

• If you become unsure about what to do at any point, do not hesitate to ask for technical assistance even if you did not book it in advance.

Measurement Process

Ready the System

1. Double-click on the icon located on the Windows Desktop. The XP-Plus Main application screen is displayed with a dialogue box asking to “Home the System” before moving on, at the screen prompt, Left Click the Yes button to continue. The system will move the sample stage and measurement head stage to their home positions.
   

   Note: If “No” is selected the system will not home and the controls will be inactive. To minimize risks to the stylus, it is important that sample stage and measurement head be in their home positions prior to loading the sample. 

2. A dialogue box appears with a message “Homing is complete”. Left Click on the OK button to continue.
3. The system is now ready to use. 

Load the Sample

1. If the stage is not already at the sample load position (closest to the operator and out from under the stylus), Select “Home the system” from the Tools menu.
   
2. After the stage moves to its forward Load position a message will appear on screen telling the user the stage is at the home position.  Press the Enter or Left Click the OK button to
   continue.
   Open the sample stage cover and load the sample on the stage table. 
3. Note: After the sample is loaded, uses the plastic tweezers located near the XP-200, to slide it to the stage center. This is to avoid scratching the stage with metal tweezers. 
4. (Optional) Toggle the vacuum switch to “on” if necessary: Left Click on the Vacuum button located on the Main software screen in the Scan Stage control panel, as shown in Figure 2. Users may find the vacuum unnecessary for their sample and can skip this step. Vacuum may be necessary if the sample bow makes measurements difficult; but it makes damaging the stylus more likely if the latter hits a step higher than its tip bevel. Vacuum may also be necessary for steps higher than 10 µm, because the stylus may otherwise push the sample when it hits a step going up.
5. Move the stage in the Y+ direction using the X-Y Stage controls until the sample is positioned under the measurement head. The user can see roughly how close the sample is with the naked eye.
6. Use the X-Y controls to “fine” position the sample for a measurement (see next section for more details). 
7. Close the sample stage door cover. 
   

   Note: Be sure that the measurement head is above the sample and clearly above the surface in the Video window or by using the naked eye to see that the tip is off the sample surface before closing the stage door cover. The Video window is automatically opened by the XP Plus main application when it starts. 

Position the Sample

1. Using motor controls, move the sample stage so the sample is under the video camera.
2. When you have roughly placed the sample under the camera, use the Z Stage controls to lower the stylus until you can see the stylus and sample in the Video Window.
   

   Note: Do not bring the stylus down too quickly or you may crash the stylus into your sample surface and damage one or both of them. The scan is along the Y axis: “normal/reverse” direction is towards/away from the operator and Y-/Y+, up/down in the video window. 

3. Avoid contacting the surface using the manual Z-stage controls: you can see where the stylus will touch the sample by left-clicking on the “engage” button on the application window.Then raise the stylus manually (careful, the control is counter-intuitive) to a safe distance above its surface.
4. Use the X-Y fine position controls to adjust the sample under the stylus until it is the desired position for a measurement. Repeat (3) and (4) until satisfied. The stylus final position here is not in contact with the surface. 

Scan the Sample

1. Select the Scan Parameter Tab on the bottom portion to be visible.
2. Select the scan parameters appropriate for the measurement; remember that the scan is along the Y axis: “normal/reverse” direction is towards/away from the operator and Y-/Y+, up/down in the video window.
3. Press the Scan Button located in the upper left corner of the Video Capture Window. The stylus automatically lowers towards the sample surface until it engages the sample surface and then the stage starts to move along the Y axis. If anything happen during then scan, it can be stopped at any time by pressing the STOP button located just besides the SCAN button. Then call tech assistance as the Profilometer recovery is not obvious. 
4. The RTD (Real Time Display) will show the profile as it is scanned.
5. When the scan is completed, the stylus lifts off the sample surface, the stage returns to its starting position above the start-of-scan location, and the Data Display window is opened with the profile plotted in dimensioned coordinates. 
6. When scanning, you may notice a significant tilt so that the profile displayed in the Real Time Scan Display window is at a severe diagonal or even clipped by moving off scale (getting clipped). This can be adjusted with the tilt adjustment, if necessary. The stage has an adjustment along the scan direction. This adjustment dial changes the tilt along the Y-axis (toward or away from the front door panel of the stage). Below is a description for adjusting the stage in the case of the profile tilting uphill.
   

   Note: The sample being measured is assumed to be placed at the center of the stage.

7. The stage tilt adjustment knob is in the front of the sample stage:

• Turning the knob clockwise moves the front of the stage up.
• Turning the knob counter-clockwise front of the stage down.

Trick: if the trace is leaning down on the right, rotate the knob to the right (CCW). If the trace is leaning down on the left side, rotate the knob to the left (CW).

Read the Profile

After the scan is taken, a new Data Window displays the profile. The profile appears in the graph display; the Data Control Tab is automatically opened along the right side of the XP-Plus Application Window. The Data Control Tab displays the cursor information and software leveling controls. 

The cursors positions are displayed in real-time in the Data Control Tab. There is always a set of Primary cursors displayed in a Data Window, the Reference and Measurement cursors (R and M respectively). 
 
To move the cursors:

• To move the R cursor, position the mouse on the R cursor, Left Click and hold the button. Move the mouse right or left to reposition the cursor in a desired location.
• To move the M cursor, position the mouse on the M cursor, Left Click and hold the button. Move the mouse right or left to reposition the cursor in a desired location.

 
The Profile may be software-leveled by positioning the R and M cursors along the line to be leveled, and then left-clicking on the “Level data” button. 

Delta Width and Delta Height calculate the difference or X distance between the two cursors and the difference or Z height respectively where the cursors intersect the profile.

• The Data Width - The horizontal distance between the R and M cursors along the X axis.
• The Delta Height - The vertical distance between the R and M cursors where they intersect the profile along the Z-axis.