Microelectronics Research Center

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Video Training Script for the Plasma-Therm PECVD

Part 1: Introduction

A PECVD or plasma enhanced chemical vapor deposition reacts gases in a RF or radio frequency induced plasma to deposit materials such as silicon dioxide and silicon nitride.

This PECVD has two chambers.

One is intended for silicon nitride depositions and has:

  • 2% Silane in Nitrogen
  • Ammonia
  • Nitrogen
  • And 10% tetrafluoromethane in oxygen connected.

The other chamber is intended primarily for silicon dioxide depositions and is connected to:

  • 2% Silane in Nitrogen
  • Nitrous Oxide
  • Ammonia
  • And 10% tetrafluoromethane in oxygen which is used for cleaning the chamber

Machine Specifications

The Plasma-Therm PECVD can process a wide range of sample sizes. The number of samples depends on the size of the samples. A typical run can process anywhere from one to four 4" wafers. Typical deposition rates range from 100 Å/s to 400 Å/s.

Typical Processes

  • Silicon Dioxide Deposition
  • Silicon Nitride Deposition
  • Silicon Oxynitride

Now let's introduce our lab users.


Part 2: Parts

We will now go over the various parts of the Plasma-therm PECVD

Monitor and Keyboard
Here we have the monitor and keyboard.

Two Chambers
Here we have the two chambers.

Emergency Off Button
Here we have the emergency off button.


Part 3: Loading a Sample

  1. Login to the machine.
  2. Press the ON button at the bottom of the screen.
  3. Highlight Utilities, Select Active Chamber, and choose the appropriate chamber. In our case, we will choose the left chamber.
  4. Press the STANDBY button at the bottom of the screen.
  5. Highlight Utilities, Vent.
  6. Listen for the sound the chamber venting. Once you hear a nitrogen escaping from the chamber, lift the chamber door. If the nitrogen does not turn off automatically, highlight Utilities, choose Close Gates.
  7. Load sample into the center of the chamber.

Part 4: Running a Recipe

  1. Highlight Process, choose Load Recipe.
  2. Press the READY button at the bottom of the screen.
  3. After READY parameters have been applied, hold the chamber cover down and press the RUN button at the bottom of the screen.

Part 5: Unloading a Sample

  1. After the process is over, press the STANDBY button at the bottom of the screen.
  2. Highlight Utilities, then Vent.
  3. Listen for the sound the chamber venting. Once you hear a nitrogen escaping from the chamber, raise the chamber door. If the nitrogen does not turn off automatically, highlight Utilities, choose Close Gates.
  4. Unload the sample from the chamber.
  5. Highlight Utilities, then Pump Chamber.
  6. Highlight Utilities, Logout.

Part 6: Creating a Recipe

NH3 5

SiH4 200

CF4O2 0

N2 900

Lovac

900MT

We will build a recipe for a standard silicon nitride deposition. In general your recipe should have four steps.

Recipe Steps:

  • An initial step
  • Two process steps
  • And an End Step

From the process menu choose build to create a new recipe or edit an existing one. A list of the recipe steps will be displayed on the right side of the screen. To edit a step, double click on it. All recipes start with an initial step. This step will evacuate the chamber and bring the chamber to the desired operating temperature. Set the pressure to 40 mTorr and the time to 30 seconds. This will cause the system to evacuate as much air as possible before starting the process. Do not attempt to use pressure set points below 40 mTorr. The chamber will evacuate as much as possible regardless of the set point. Set the temperature to your desired process temperature. Note that the temperature is measured in degrees Celsius. You may describe your recipe in the description box. The first few words will be displayed by the file name when you are loading your recipe.

Then click "Ok."

To create a new step, select the step that will go before the new step. In our case we will highlight the initial step and choose "Process" at the bottom of the screen. You will usually want two process steps. They should be identical with a few exceptions. The first process step is a gas purge step, and it also sets the process pressure. It allows the chamber pressure and gas flows time to stabilize. Because the RF power is off, no processing will actually take place during this step.

Process Step dialogue box has four major areas:

  • Time
  • Pressure
  • Gas Flow
  • And Power

The first process step's "Terminate by" time should be set to fixed time. This step will be used to stabilize chamber conditions. The time here is not critical, but one 30secs is good. Leave the power set to zero in the first step. Set the gas flow rate for each gas here. Flow rates are given in sccms: standard cubic centimeter per minute. Set the pressure you want for the process here. The process pressure is measured in mTorr. The system is optimized to run SiO2 and SiN2 deposition at 900mTorr.

 

The second process step will actually perform your process. If you set its "Terminate by" time to variable time, you will be prompted for the process time each time you run your recipe. This is more convenient than editing your recipe each time. However, you can set the process time to fixed time and set the time here if you prefer. Here's an example of what the prompt looks like. The pressure and gas flow rates should be the same for both process steps. Set the power here for the second process step. Please do not exceed 400W. Then click "Ok." For Nitride and Oxide deposition, please do not exceed 30W. For all other processes, please do not exceed 300 W

All recipes have an end step that evacuates the chamber. Set the pressure to 40mTorr and set the time to 60 seconds. The automatic vent features does not work properly and should not be used. After you are done building or editing a recipe, you must save the file. When you modify a process, you only change the copy on the disk. If the process is already loaded, you will need to reload it for your changes to be reflected.

Choose a recipe name and save the process.

Part 7: Closing Remarks

After watching this training video, you should know how to:

  • Load a sample
  • Run a recipe
  • Unload a sample
  • Program a recipe

If you have any questions, please direct them to the trainer of this equipment. Please do not ask Charlie.

Warning: Please do not touch the sample holder. The area is very hot.

Warning: Please do not try to open the system door while the chamber is running.

Warning: Please do not try to run the process if the chamber door is open.

Warning: Please do not restart the computer.