The MRL Furnaces USED FOR 1. Making Silicon Oxide films from 10nm to 2um thickness 2. Annealing with temperatures from 30 800C and times from 5min to 2days 3. Diffusion with temperatures from 30 1100C and times from 5min to 2days 1. Choosing temps and times 2. Physics of the furnace 3. Logging on to the system 4. Writing a recipe 5. Sample preparation 6. Running the MRL 7. Unloading and Idling the MRL 8. Observing records of the process 9. Tools for measuring oxide thickness 10. Troubleshooting 11. Contact information THIS MANUAL COVERS
1. Choosing Temps and Times Oxidations can be wet or dry for Silicon Oxide thicknesses above or below 100nm respectively. For wet oxidation, find your desired thickness on the vertical axis (left) of the graph below, and trace the line to your desired temperature (typically 1100C). From here, trace down to find your desired time. Wet oxidation Log Log plot of thickness, temperature and time Alternatively, for dry oxidations (<100nm), perform the same tracing on the following graphs instead. The one on the left is for very thin oxides, and the one on the right for slightly thicker ones. Thinner dry oxidations Thicker dry oxidations If your process includes both dry and wet oxidations, such as a "dry wet dry" process, only count the times for the wet oxidation. If you have any questions, don't hesitate to contact CNM2 staff!
2. Physics of the Furnace Most processes follow the profile shown above, though the gasses, temps and times may differ. These same steps with different parameters will work for oxidation, diffusion or annealing. The most common process, dry wet dry oxidation is shown above, and it creates a thick (0.2 2um) film of Silicon Oxide with high quality surfaces. The first and final dry steps create a high quality Silicon Oxide on the top and bottom of the film respectively. The wet step creates a very thick film of lower quality Silicon Oxide inbetween, because water actually oxidizes Silicon faster than Oxygen can. The recipes shown in this manual are for a dry wet dry oxidation, and cover each step in more detail. 3. Logging on to the System 1. First activate the MRL furnaces in badger. 2. The computer is normally left on, but if you find it off, you will need to log in to the system and open the MRL software. The computer's user name is GCA, and the password is fieldhand. 3. Open the ICCI GMI folder and run the Icci Gmi Cell Manager Program.
4. In ICCI GMMI, select "login" from the file menu and type in user name Eng, password Eng. You now have full access to the tool. 4. Writing a Recipe A) Making a new recipe If you'd like help writing a recipe, don't hesitate to ask! This covers how to make an oxidation recipe from a template. A1. From the ICCI GMI furnace overview window, click View and then Recipe Manager. This will open a new window. A2. In the recipe manager, select recipe 218, right click it and select copy.
A3. This will bring up the copy dialog box select new recipe number. A4. In the following dialogue box, choose any available recipe number, shown by smiley faces. This example chose "13", but you will need another number. A5. Finally, select which tubes you plan to work in. MOS clean oxidations for Pyrox 1, general oxidations and diffusions for Pyrox 2, and anneals for Anneal. B) Opening Recipes; Making and Editing Steps B1. You will now have your own recipe to work from. Open your recipe by double clicking it.
B2. Change your recipe as desired and click File then Verify Recipe. If it's a success, click File then Save. B3. Right click individual steps to copy or delete them as desired. B4. To edit a step, double click it. This brings up the edit step dialog box, detailing all aspects of the step. On the first page you will find the step's number, name and time (or time range). On subsequent tabs you'll find the temperature of the step, what gasses flow, and other details. C) Changing Temperatures C1. From the Edit Step Dialogue (from B4) Click to the temperature tab to alter the temperature of a step.
C2. If the temperature you want is not an option (it likely isn't,) check for the temperature in the recipe tables by clicking Tables then Recipe Tables. If you see your temperature here, simply right click it and select a number that isn't already in use (typically 3 will work). C3. If you don't see your temperature here either, close this box and click Tables then Master Temperature Tables. From here, make a new temperature. Make its name and all the temperatures within your desired temperature, for this example 409C. Then, click OK to create the entry, and click OK again to close the master temp tables. C4. Go back to the recipe tables by clicking Tables then Recipe Tables. You can now select the temperature as described in C2. C5. Now you will have access to the desired temperature in the temperature tab of any step, as described in C1. You can re enter a step by double clicking it, and go to the Temperatures tab to select your new temperature. You will need to set your temperature in each step seperately.
D) Changing gas flow rates D1. Changing gas flow rates works in a similar way, but the flow rates you need will almost always be choose able from the presets. In the Gasses tab you can individually change the flow rate of each gas. Each step must flow a gas; for non oxidizing steps you can flow Nitrogen as an inert gas. D2. If you change which gasses flow, click to the Digital Outputs tab and select GAS1, GAS2 or GAS3 for Nitrogen, Hydrogen and Oxygen flowing respectively. Common Gas Flow Rates Most Steps Dry Oxidation Wet Oxidation Nitrogen 5 0 0 Hydrogen 0 0 5.7 Oxygen 0 5 3 E) Programming Special Functions E1. To make the tool perform a special function like load/unload or wait it's easiest to just copy a step that already has the function. However, if you d like to make these from scratch, you can access these capabilities from the step edit box by double clicking the step.
E2. To have the system wait for an operator before continuing, go into the Step Exit Condition tab and set it to Digital Input and 13. E3. To set the system to load/unload a boat, go to the Digital Output tab, and select boat in/out respectively. Then go to the Step Exit Condition tab and set it to boat. 5. Sample Preparation For Pyrox1 (the MOS clean top tube) use only virgin wafers or wafers that have been recently RCA cleaned. For more info, contact staff. For Pyrox2 (the normal use middle tube) and Anneal (the metal ok bottom tube) you can use any wafer that does not have organics on it. Wash off all resist with PRS3000 or Acetone. Some metals are not ok for Pyrox2, so please ask before introducing any metals. 6. Running the MRL A) Opening Gasses A1. Choose the gasses you need. If you're annealing in Nitrogen then no specific gasses need to be opened because the Nitrogen supply is always open. For a dry oxidation, open an Oxygen cylinder. For a wet oxidation, open an Oxygen cylinder and a Hydrogen cylinder. You can find the gas cylinders in the semi clean room accessible through the chase adjacent the MRL furnace.
A2. To open an Oxygen cylinder, simply open the cylinder's valve and the tiny safety valve. The big regulator 'valve' in the middle is carefully adjusted and should not be touched. When you open a cylinder, make sure not to open it too far if the valve opens a few turns and stops, close it by a couple complete turns. Open These Not These A3. To open a Hydrogen cylinder, go to the Hydrogen cylinder cabinet and open one of the Hydrogen cylinder valves. Don't touch anything else in there, please! A3 (continued). After this, check the Gas Safety Monitor up above. If the Remote Shutdown light is active, try pressing the Alarm Reset button. If this doesn't clear the remote shutdown please seek help from staff. Otherwise, press the Open Valve button to open the Hydrogen. B) Uploading a Recipe & Loading Wafers B1. Upload your recipe by clicking Send then Recipe. Select your recipe and hit ok. If the tool complains that it needs to be idled: make sure no one else is using the tool, press Start/Abort then Abort and finally press the white Start button on the side of the MRL. Now the tool should be idled, and you can try uploading your recipe again.
B2. Without needing to press anything else, the boat should start opening out of the furnace in a few seconds. After the boat comes out of the furnace, wait 5 minutes for it to cool, then load your samples using a thermal glove and the metal boat holder. Though the picture shows only one wafer, we appreciate users who work with many wafers at once because the furnaces are very costly to run. B3. Now that your samples are on the tool, press Start then Start Recipe. For many recipes, the tool will beep and say Waiting for DI Acknowledge. In this case, just press ok or hit the white start button on the side of the tool. From here, the recipe will run automatically, typically by loading the wafers into the furnace. C) While the recipe is running C1. The recipe runs automatically and can be left alone except for the beginning of wet oxidation steps. At the beginning of wet oxidation steps, the furnace goes into a temporary trouble state, which can be cleared by pressing the RESET button on the top right of the flow controller in the cabinet near the Oxygen cylinder. If the trouble state doesn t clear after pressing the RESET button twice, contact staff. Typically nothing bad happens in this case, and the process can simply be restarted. To know when the wet oxidation step starts, you can check the recipe and add up the times of all the steps that come before it.
C2. You can keep track of the temperature and gas flows by clicking the tabs on the main screen. If this screen closes, you can get back to it by opening ICCI GMI and double clicking on the tube you re using. If ICCI GMI complains that a tube is already open, then the window that comes up may not be for your tube. Either double check the tube name or close the window and try again. This picture shows Hydrogen flowing properly after resetting the flow controller as in step C1. 7. Unloading and Idling A) Unloading A1. When your recipe has finished and you wish to remove your samples, simply press the white start button again, or press OK on the Waiting for DI Acknowledge box. This will start removing the boat from the furnace automatically. If you need to force the boat to load/unload you can also use the manual boat load toggle located on the furnace. Please return the toggle to AUTO when you finish, and don t adjust the rate dial unless you ve spoken with staff first. A2. When your wafers come out of the tool they will still be hot enough to start fires. Please wait 15 minutes for them to cool, and remove them like they were loaded in section 6, step B2. B) Idling B1. When you re done processing you must idle any tubes you used. Simply press Send then Recipe as before, then send one of the idle recipes from the bottom of the list. Press Start and Recipe to run the idle recipe. The boat should load back in at this point. Finally, go close any cylinders you opened, and if you used Hydrogen, press Shut Down on the Gas Safety Monitor shown in step A3.
8. Observing Records of the Process 1. Open the Graphic Process Analyzer by clicking View then Graphic Process Analyzer. In the box that appears, select the date of the process you re interested in (often today ). In the next box, the parameters on the right are graphed, and those on the left are not. Move them one way or the other by double clicking. A typical graph of temperature appears to the right. You can see how set points and actual values differ for temperature and gas flows. 9. Tools for measuring oxide thickness The Nanometrics Spectrometer Nanospec is the quickest and easiest way to measure the thickness of the oxide film you ve grown. As an alternative, you can also use a Dektak Profilometer by patterning your oxidized wafer with photoresist and etching in BOE. Finally, you can photograph and measure the oxide layer by cleaving the oxidized wafer and edge mounting it in the NovaNano SEM. 10. Troubleshooting When in doubt, call staff. 11. Contact information Mike Irving 530 752 2241 mnirving@ucdavis.edu Corey Wolin 530 752 1094 cdwolin@ucdavis.edu Yusha Bey 530 752 9831 jasmall@ucdavis.edu