Cambridge Nanotech Fiji ALD
- Former user (Deleted)
- Bradash, Mihailo Rayko
- Richard Harlan
/wiki/spaces/BNCWiki/pages/6236192
Cambridge Nanotech Fiji ALD - Staff
iLab Name: Fiji200 ALD
iLab Kiosk: BRK Growth Core
FIC: Zhihong Chen
Owner: Mihailo Bradash
Location: Cleanroom - G Bay
Maximum Wafer Size: 8"/200 mm
Overview
| Type | Films Available | Restricted Materials | Available Gases | Wafer Size |
|---|---|---|---|---|
| Thermal / Plasma ALD | Aluminium Oxide Hafnium Oxide Silicon Oxide Zirconium Oxide | Backside must be clean No outgassing materials in mTorr range No thermally unstable materials | Carrier Gas: Argon Plasma Gases: Argon, Nitrogen, Oxygen, Hydrogen | Small pieces up to full 8 inch wafer. Maximum sample thickness is approximately 6mm. |
| gas valve numbers |
|---|
0: H2O 10/2022 1: HfO2 06/2023 2: SiO2 06/2023 3: ZrOx 09/2023 4: Al2O3 09/2023 5: N/A |
Growth rates (Thermal) | Growth rates (Plasma) |
|---|---|
Al2O3~TBD | Al2O3~TBD |
| HfO2~TBD | HfO2~TBD |
| SiO2~ N/A | SiO2~0.7 A/cycle |
General Description
Atomic Layer Deposition (ALD) is a technique that takes advantage of self limiting surface reactions, the nature of the reactions ensures atomic-level thickness control and excellent conformality. Following the standard example, growth of Al2O3 film from water and trimethylaluminum (TMA) precursors will be used here to discuss the principle of ALD film growth. Recipes for other materials use different precursors, but are similar in principle and procedure.
| Principles of Atomic Layer Deposition Film Growth (Aluminum Oxide used for this discussion) | ||
| Thermal Atomic Layer Deposition - The required reaction energy comes from elevated temperatures of the sample and chamber surfaces. | ||
| Processing Steps | Images | |
|---|---|---|
| In air, H2O vapor is adsorbed onto most surfaces forming hydroxyl groups with Silicon. (Si - O - H). This is the typical condition of the substrate when placed into the chamber. |
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| The four steps of the ALD Cycle consists of the steps shown to the right. Repeated ALD cycles build self limiting atomic layers at a rate of approximately one angstrom per cycle. | 1. Next, Trimethylaluminum ((CH3)3Al) is introduced into the chamber. Trimethylaluminum reacts with the hydroxyl groups, creating methane as a gaseous reaction byproduct. Al(CH3)3 + :Si-O-H > :Si-O-Al(CH3)2 + CH4 |
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2. Trimethylaluminum continues to react with the adsorbed hydroxyl groups until the surface is passivated. Trimethylaluminum does not react with itself, once all the available hydroxyl groups have been consumed the reaction stops. This self limiting causes the perfect uniformity and conformity of ALD processing. The excess Trimethylaluminum and CH4 byproducts are pumped away. |
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3. The second precursor, H2O, is introduced to the chamber. Water vapor reacts with the CH3 groups on the new surface, forming Al-O bridges and hydroxylating the surface. Methane is produced as a byproduct of this reaction. 2 H2O + :Si-O-Al(CH3)2 > Si-O-Al(OH)2 + 2 CH4 |
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4. H2O continues to react with the CH3 groups until the surface is passivated. Water vapor does not react with OH groups, once all the available OH groups have been consumed the reaction stops. This self limiting causes the perfect uniformity and conformity of ALD processing. The excess water vapor and CH4 byproducts are pumped away. |
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| One complete ALD cycle will produce approximately 1 angstrom (0.1 nm) of film thickness. The ALD cycle can be repeated in this way until the appropriate film thickness is grown. | Two reaction steps in the ALD cycle: Al(CH3)3 + :Si-O-H > :Si-O-Al(CH3)2 + CH4 2 H2O + :Si-O-Al(CH3)2 > Si-O-Al(OH)2 + 2 CH4 | |
| Plasma Assisted Atomic Layer Deposition - Plasma is used to crack precursor molecules and/or add energy for surface reactions. | ||
| Processing Steps | Images | |
| Oxidizing step of the plasma assisted atomic layer deposition cycle. | 3. The plasma assisted ALD cycle proceeds exactly as above until reaching step 3. During this step, O2 plasma or Ozone (O3) is introduced into the chamber. The oxygen radicals react with the CH3 groups on the new surface, forming Al-O bridges and forming a hydroxylated surface. CO, CO2, H2O, and CH4 are produced as byproducts of these reactions. Oxygen Plasma reaction during Al2O3 film growth 4 O(plasma) + :Si-O-Al(CH3)2 > Si-O-Al(OH)2 + CO2 + H20 |
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ALD Temperature Window
The chemical and physical conditions necessary to obtain self-limiting growth differ for each ALD process. Furthermore, each process is deemed to have a specific temperature window in which ALD behavior is obtained. An idealized temperature window is plotted to the right where the growth per cycle is plotted as a function of temperature. The ideal temperature window represents the temperature range over which the growth per cycle shows weak or no temperature dependence. This is indicated by the horizontal in the plot to the right. Outside the temperature window, chemical and physical processes can disrupt the ALD behavior. Condensation - At low temperatures, some precursors and co-reactants can condense on the surface, leading to an increase in growth per cycle. Low reactivity - The reactivity of the molecules with the surface sites can be too low because of limited thermal energy at low temperatures. This prevents saturation of the reaction and leads to a decrease in growth per cycle. Decomposition - At high temperatures the precursors or co-reactants can decompose, leading to a CVD component and an increase in growth per cycle. Desorption - At high temperatures the film itself or the reactive surface groups involved may desorb or etch. This leads to a decrease in growth per cycle. |
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Safety Considerations
Danger! Fire Hazard! Trimethylaluminum (TMA) is a liquid at room temperature and is pyrophoric. This means that it burns upon exposure to air. TMA reacts with water vapor in the air. For this reason, the TMA bottle may only be opened in a glove box with inert atmosphere by experienced professionals.
Temperature of the precursors and heating jackets should not exceed safety or decomposition temperature of the chemical being used.
Maintaining cleanliness and proper function of the system is critical for high quality, low leakage dielectric films. It is the responsibility of all users to follow standard operating procedures and to use the system within the prescribed limitations.
You must gain permission from Professor Zhihong Chen and/or the staff engineer before you can be trained for this tool. You will be asked to describe your intended use and sample stack. If you intend to process other substrates and stacks in the future you must first gain permission from Professor Zhihong Chen and/or the staff engineer.
Processing substrates or stacks without prior approval may result in chamber contamination due to outgassing/melting of the materials. This will result in loss of privilege to the tool and your PI may be held accountable for the cost of restoring the tool to operating condition.
Specifications
Available Chemistry
| Precursor | Skeletal Formula | Notes |
| H2O (Water) |
| Ultrapure Water (UPW) from the Birck UPW system. Filled directly from faucet to stainless steel cylinder, contamination prevention. Chemical Formula: H2O CAS Number: 7732-18-5 |
| Aluminum Oxide |
| Trimethylaluminum, min. 98% Chemical Formula: (CH3)3Al CAS Number: 75-24-1 Strem #98-4003 |
| O3 (Ozone) |
| See Ozone Delivery System Wiki for details Chemical Formula: O3 CAS Number: 10028-15-6 |
| Hafnium Oxide |
| Tetrakis(dimethylamino)hafnium, 98+% (99.99+%-Hf, <0.2%-Zr) Chemical Formula: Hf(N(CH3)2)4 CAS Number: 19782-68-4 Strem #98-4021 |
| Silicon Oxide |
| Bis(diethylamino)silane Chemical Formula: SiH2[N(CH2CH3)2]2 CAS Number: 27804-64-4 Strem #98-8810 |
| Gas | Max Flow Rate (sccm) | Notes |
|---|---|---|
| Argon Carrier | 200 | Flows through the manifold, into the process chamber. This gas is used to carry the precursors from the precursor manifold, into the process chamber. |
| Argon Plasma | 1000 | Flows from the plasma generating coil (above the chamber) to the process chamber. If not using plasma, this gas should still be used to prevent precursors from entering the quartz plasma tube. |
| Nitrogen | 200 | Can be used alone, or as a fraction of a plasma gas mixture. |
| Oxygen | 200 | Can be used alone, or as a fraction of a plasma gas mixture. Mass flow controller cannot be powered at the same time the Hydrogen controller is powered. |
| Hydrogen | 200 | Can be used alone, or as a fraction of a plasma gas mixture. Mass flow controller cannot be powered at the same time the Oxygen controller is powered. |
Thermal Limits
| Heater ID | Max Temp |
|---|---|
| ALD Valves (17) | Remains set to 150 C in all conditions and processes. |
| Precursor Delivery (16) | Remains set to 150 C in all conditions and processes. |
Reactor 1 (13) | 250 C |
| Reactor 2 (14) | 250C |
| Chuck (15) | 500 C |
| Cone (12) | 250 C |
| Precursor Heating Jacket | 200 C |
RF Plasma Controls
| RF Source | Max Power (watts) |
|---|---|
| ICP Coil | 300 |
Available Standard Recipes
Sample Requirements and Preparation
Sample Specification Clean, vacuum compatible non-outgassing substrates and film stacks. Backside must be clean and free of any metals or photoresist to prevent contaminating the sample carrier. Check with Professor Zhihong Chen or staff engineer for compatibility of your sample. Maximum sample size: Small pieces up to full 200 mm diameter wafer. Approximately 6mm of vertical clearance when inserting the sample carrier, will accommodate thick non traditional samples. Common Substrates: Si, SiO2, GaAs, Glass, Quartz. Common Films (None allowed on backside): Ti, Au, Ag, ......... Not Allowed: ..... | |
Small Samples Small silicon samples, on the order of 5 x 5 mm and smaller, can be lost in the chamber during pumping. These samples cannot be retrieved. A good solution to this problem is presented in the image to the right. Two glass slides are placed such that they are perpendicular to the loading tool arm. The sample is placed between these two slides to shield the sample from gas flows created by initial pumping and stabilize its position on the chuck. New glass slides are not clean! You must clean them using the standard TAI solvent cleaning process before placing them on the chuck or inside the ALD chamber. |
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Software Interface Reference
The control program allows the operator to control the ALD valves, pumping system, heaters, and to set deposition recipes. Do not close the program while the system is running. | |
| Section 1 - System Control buttons. These buttons act as toggles in that their function changes after pressing them. For example, the Pump button changes to Vent and back to Pump when repeatedly pressed by the user. Program Switch Pump/Vent Switch
Heaters Switch
Run Switch
When a process is running, “Program”, “Pump/Vent” and “Heaters” buttons are grey and not |
| Section 2 - Recipe Timing Information Remaining cycles – During a running process, displays the number of cycles remaining in the current goto command loop. Timing Drop Down Options
Main Chamber - Displays current pressure chamber in real time. |
| Section 3 - Recipe Table Column 1 - Automatically assigned line number - Recipes are executed in numerical order from top to bottom of the table. Column 2 - Instruction - These are the commands used to operate the tool. There are many commands, the basic commands are explained here. Wait - Commands the tool to wait in current condition for specified number of seconds. (# column left blank) Flow - Sets the set point for the specified mass flow controller. # column identifies the mass flow controller, while Value column defines flow in SCCM. Heater - Sets the specified heater's set point. # column identifies the heater, while Value defines temperature in Celsius. Stabilize - Commands the tool to wait at this line until specified heater setpoint is reached. # column identifies the heater being referenced, while Value column is left blank. Pulse - Commands the specified ALD valve to open for the set time. # column identifies the ALD valve, while Value column defines valve open time in seconds. goto - Creates a looping command set and is how we will define the ALD cycle within our recipe. # column identifies the recipe line number that will be returned to in the loop, while Value column defines the number of loops. This parameter defines the film thickness grown by this recipe. Column 3 - # - Typically used to identify the hardware being referenced by the command. The goto command is one exception. Column 4 - value - Typically used to set the operational set point of the hardware being referenced. When logged in as an operator, the command list is not available to you and editing column labeled Instruction is not recommended. Editing of the remaining table values is accomplished by selecting a field and typing in numerical values. You can edit commands, but be aware that those commands cannot be saved and you will need to record that separately via a photo or notes on your own. If you have optimized a specific recipe for your use, speak with the engineer and a custom recipe can be created for you. |
| Section 4 - Mass Flow Controllers (Recipe controlled, user intervention typically not required in this area) The Mass Flow Control section displays the current set point (left side, white area) and the actual current flow rate (right side) for each of the available system gases. The buttons on the left allow you to power/remove power to a valve. Bright green is Power ON, while dark green (shown) is power OFF. When the hydrogen or oxygen valves are powered off, the gas interlock forces a several second purge of the gas lines. |
| Section 5 - Plasma control (Recipe controlled, user intervention typically not required in this area) |
| Section 6 - Process Chamber Pressure Plot Area This plot tracks the process chamber pressure reading from the pressure gauge installed in the pumping line assembly. Pulses of the precursors show up clearly on the plot. |
| Section 7 - Heater Control Area (Recipe controlled, user intervention typically not required in this area) The heater control area (right side of screen) allows direct control of each heater. Individual input/display clusters corresponds to a control circuit from the electronic box. Enter the temperature set point into the white area. The current temperature reading is shown in the red area. If an RTD is not connected to the corresponding port (a problem exists), the temperature reading displays NC and you will not be able to input a temperature for control. |
Standard Operating Procedure
Arriving at the Tool
| Instructions | Images |
|---|---|
Prepare for your process Upon arriving, you should find the system running idle, having completed the IdleSystem recipe after the previous user finished. If you do not find the system in this state, please verify previous user has completed their work. It is recommended that you now execute the idle system before processing your sample. That recipe takes about 10 minutes to run and will clean up the chamber in preparation for your growth. Assuming the idle system recipe has been completed before your arrival, and the system is ready for your use, please verify the gas flows below and then log the main chamber pressure in the spreadsheet located on the desktop called "Fiji F200 Log Sheet...".
Complete the log entry with your PU alias, date of growth, sample description, chamber temperatures, material, and # of cycles. |
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Loading Your Sample
| Instructions | Images |
|---|---|
Vent the System to Load Your Sample Press the Vent button on the left side of the control panel. Wait for the system to vent to atmosphere, this will take 10 to 15 minutes. If you see that you are not near complete vent after this time, you can try pressing the pump button, followed by the Vent button again. The pressure gauge in this system is not accurate at atmospheric pressures. You can clearly identify full vent when the pressure plot levels off. To help increase the speed of venting, you can turn up the carrier gas flows to the maximum flow rate. Mass flow controllers 0 and 1. There is nothing holding the door closed except for the pressure difference between the atmosphere and the chamber vacuum. Do not attempt to force the chamber door open. When the system is vented, the door will open freely. The knob that you see does not operate a latching mechanism, there is no latching mechanism on this door. |
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Load Your Sample The materials being removed from the chamber are HOT! Risk of burns! Avoid making direct contact with the sample carrier or any materials present on the sample carrier. Do not touch or place anything on the hot sample carriere that is not thermally stable. Transfer of materials onto the sample carrier will contaminate the carrier and the chamber if placing inside. ONLY use metal tweezers to place and remove your samples from the sample carrier! Open the door to the process chamber, it should open freely. Looking inside you will find two metal hooks facing downward. On the wall next to you, you should find the sample carrier handling tool. Grab the carrier handling tool by the black handle with your right hand, and the shaft with your left hand. Do not touch any of the chamber parts, they are hot, and you can contaminate the surfaces. Place the arc end under the metal hooks of the sample carrier and pull the carrier from the chamber. Make sure both hooks are fully engaged and be careful not to allow the carrier to fall off the hooks while transfering to the work table. You can place your samples directly onto the center of the chuck, no carriers or mounting is required. Only use metal tweezers as plastic tips will melt onto the hot sample carrier. Place the sample carrier back into the process chamber. Insert the carrier until it full seats against the outer chamber wall. Allow the tool to drop off the hooks, use the tool to press the carrier to ensure it is fully seated against the chamber wall. Close the chamber door and press the PUMP button. You will hear a low pitch grinding sound that is normal, this is the pump removing the initial atmospheric load from the chamber. If that noise continues for more that a second or two, or is very loud, the chamber door may not be fully closed. Please inspect and try again. |
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Recipe Selection and Setup
| Instructions | Images |
|---|---|
Load the Default Recipe for Your Selected Film Right click on the Recipe table, in any of the cells, and the Load Recipe option will appear. After clicking, and traditional file browser will open for recipe selection. Navigate to the appropriate location and select the recipe you intend to use. See Available Standard Recipes section for more information regarding locations and recipes. |
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Set the Desired Film Thickness After your selected recipe loads into the recipe table, you will see the recipe name at the top. Scroll down the table until you find two lines highlighted in the same color, in this example they are highlighted yellow. These two lines identify a looping command, typically the ALD cycle. The number in the # column, is the line number where the recipe will go when the goto command is executed, in this example line 24. Find the line who's instruction is "goto", and set the Value column for desired film thickness. The number shown in the Value column is the number of loops to be completed. This number directly defines the thickness of film that will be grown. Each loop will grow 1 angstrom of film. In the example shown to the right, 100 loops=100 angstroms=10 nm of aluminum oxide film will result from this recipe. There is an 30 nm (300 cycles/loops) administrative limit on the film thickness allowed in one growth. If you need to grow films thicker than this, you will need special permission from the engineer and Professor Zhihong Chen. |
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There are many predefined user recipes preloaded on the system. You will need to select from these recipes and cannot create custom recipes from scratch. The provided recipes should allow you to perform any acceptable growths with minimal inputs from the user. If you desire to do something unique please contact lab staff for more information.
Running the Recipe
| Instructions | Images |
|---|---|
Starting the Recipe and Recipe Status Once you have loaded your desired recipe, and modified the goto command to set your desired film thickness, the tool is ready to Run the recipe. Make sure you have loaded your sample and pumped the system down using the PUMP button. Press the START button on the left panel, followed by YES on the pop up window. If the system interlocks were all met, then the recipe will start to execute from line 0 in the recipe table, and progress down the table one line at a time. If the recipe does not start to execute after pressing the START button, check the status bar for error message and correct as necessary, then press START again. The status bar displays the current status of the tool. When recipes are running, it will display "Running...." followed by the line number of the recipe table that is being executed and any messages related to that command. When the recipe is finished, the status bar will display "Run has completed" |
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Verifying Recipe Execution During the recipe execution, the pressure plot will display the pressure changes in real time. You will see many various pressure changes as the tool changes carrier gas flows and pulses precursors. In order to make sure the recipe is executing and delivering precursor to the chamber as expected, we watch the pressure plot for sharp peaks as shown to the right. These peaks are the precursor pulses being introduced to the process chamber and indicate a good flow of material. Notice there are two different peak heights shown to the right. Remember that we are looping through two pulses of material, one is water and one is Trimethylaluminum (TMA) in this example. This means that every other pulse is the same material, water or TMA. We want to make sure that each material produces consistent peak heights when compared with itself, meaning every other peak should be roughly the same. In the example to the right, the peaks aligned with the green line are water, and the peaks aligned with the red line are TMA. Notice the peaks are not exactly the same even within one material. This is normal, they just need to be close to indicate a good growth run. If one or both peaks tapers off significantly or to zero, that would indicate a problem, loss of material (empty bottle most likely). See How do I know if my growth proceeded as expected? FAQ for more information regarding reviewing pressure traces post run. |
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Removing Your Sample
| Instructions | Images |
|---|---|
The materials being removed from the chamber are HOT! Risk of burns! Avoid making direct contact with the sample carrier or any materials present on the sample carrier. Do not touch or place anything on the hot sample carrier that is not thermally stable. Transfer of materials onto the sample carrier will contaminate the carrier and the chamber if placing inside. ONLY use metal tweezers to place and remove your samples from the sample carrier! For detailed instructions see the Load Your Sample section to remove your samples. Once the recipe has been completed, and the status bar says "Recipe has completed," vent the chamber, open chamber door, and remove the sample carrier placing it on the worktable. Remove your samples using the metal tweezers, and place the empty sample carrier back inside the chamber. Close the chamber door and press the PUMP button to place the system under vacuum. |
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Leaving the Work Area
| Instructions | Images |
|---|---|
Place the System in Idle or Standby Once that recipe starts, you can leave the system unattended, it will run autonomously and leave the system in the appropriate state for idling or standby. It is important to run the IdleSystem recipe after your growth. This recipe uses oxygen plasma to clean the chamber and leaves the gas flows in a suitable condition for idling or standby. These conditions are important as they prevent undesired oxide deposits on the chamber walls. |
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Clean up the Surroundings and Work Table Throw away trash, remove any of your belongings, and place tools back in their appropriate locations. The work table surface should be clear of any objects, use the right half of the shelf above for storage of supplies and nitrogen gun. Return the sample carrier to the clip located on the wall next to the Fiji chamber door. Please be sure you have made the log book entry before leaving! |
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Questions & Troubleshooting
How do I know if my growth proceeded as expected?
The Fiji does not provide direct feedback that ALD growth has taken place. The best indication we can get from the Fiji itself is tool performance throughout the recipe. This is easily checked by reviewing the pressure peaks associated with your growth process. Upon close examination, you will find two sets of peaks, one from the precursor material, and one from the oxidizing material. These pulses alternate on the pressure graph so that one pulse will be precursor (precursor is the very first pulse in standard recipes), followed by oxidizing agent, followed again by precursor and so on for the number of cycles defined in the recipe. In a successful growth, all precursor pulses should be roughly equivalent in peak height and all oxidizer pulses should be roughly equivalent in peak height. Comparing an oxidizer to precursor pulse will only indicate differences/similarities in vapor pressure for the two materials. Also worth noting, the first couple pulses of either precursor or oxidizer may be higher than the remaining process as they have had more time to vaporize while idle. Since ALD is a self limiting process, this should have little to no effect on your growth.
| Instructions | Graphics |
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We have recently developed a tool and placed it on the desktop of the Fiji computer. You will find a spreadsheet called "Growth Check.xlsm". |
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Open this spreadsheet, and press the |
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An Open file dialog will launch for you to select the pressure log data from your growth process. This should open up in the appropriate folder by default. You will see data logs from all recipes run on the system in the form of .txt files. Find the file associated with your growth, select, and press Open. File names are formatted as: Year_Month_Day_Hour_Minute_Second_Recipe_Name.txt Hour field is in 24 hour format example: File name "2019_08_21-15-38-21_Thermal_Al2O3_250C.txt" means: The recipe named "Thermal_Al2O3_250.txt" was ran, starting at 3:38:21 pm on August 21, 2019. |
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| Spreadsheet macro will run behind the scene and end with a dialog box stating "Process Complete", press OK. |
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| You should now see a chart with data from the fifth cycle and last cycle of your process. Each frame should contain two pulses as shown in the example data. If peaks are missing or significantly different between the frames, your growth likely experienced a problem and should be investigated. |
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I'm receiving a USB failed to connect error message when starting the Fiji control software and logging in as Operator, what should I do?
| Instructions | Graphics |
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Power Cycle the Ebox and Reboot PC Turn off the rocker switch to the Ebox located just above the PC drawer on the left side of the Fiji main cabinet, just below the gas box door. Reset or power on the PC as necessary, wait two minutes for it to boot up fully and launch all processes. Turn on the rocker switch to the Ebox and wait 30 seconds for it to enumerate the USB port of the PC. Launch ALD software using the Log in as an Operator using password: ald |
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| Run Idlesystem Recipe to Restore Default Parameters After the software progresses through initialization the status cluster will display “Ready” in the upper left corner, and the status bar will display “System is ready please load a recipe from file or create one manually and then press start”
Wait until all temperatures reach their set point before proceeding. |
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What are the standard idle conditions?
| Instructions | Graphics |
|---|---|
System Conditions during idle (this is after the IdleSystem recipe has completed) Heater Controls Channel 12 (Cone): 200 C Channel 22 (SiOx 2): 0 C (NC) |
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Plasma Controls Plasma: OFF |
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Chamber Valves Door Purge: Lit green circle |
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Gas Flows Channel 0 (0 Argon Carrier (sccm)): 20 |
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Anything else I should know?
| Instructions | Graphics |
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Modifying Standard Recipes Making changes to the standard growth recipes, especially the ALD cylce, can lead to unexpected results and is not recommended. It is important that between the precursor pulses, there is no residue (except the monolayer chemically bonded to the substrate) of precursor in the process chamber. The presence of two precursors at the same time would cause immediate reaction in vapor phase, which can lead to CVD mode of deposition (non-uniform, thick coating, powder formation, accelerated contamination of the chamber). The combination of temperature, gas flow, and pump time between pulses prevents two precursors from combining in vapor phase. |
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Exposure Deposition Mode Very high aspect ratio structures (>1:10) may benefit from operating in Exposure mode. Please see lab staff if you have a need for this type of operation. Exposure mode allows precursors to sit in the chamber with pump valve closed. This can result in migration of the precursor to the valve manifold and cause deposition in the valves. Due to the issues associated with exposure mode operation you will have to make a compelling argument and be granted permission to operate in this manner. |
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Multi Dosing Deposition Mode Better nucleation on hydrophobic substrates may be achieved in multi dosing deposition mode during the first few cycles, and may be especially useful for thin gate dielectrics. Please see lab staff if you have a need for this type of operation. |
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