MVT-8X Series Sputtering Systems
Operating System
The MAT-VAC Technology, Inc. Universal Sputterer™ control software can control MVT-60X/64X (Vertical), MVT-94X/90X (Horizontal) and MVT-8X Series (Circular) series sputtering systems. While there is much in common between the systems (the recipe page, configuration page and indicators), there are several MVT-8X Series specific items. This section covers them in detail.
MVT-8X Series Service Tab
Central to the MVT-8X Series Service Tab is the "wheel" display of the chamber. This is a complex graphic and conveys information about the pressure state of the chamber, the location of the shutter, the selected target and the position of the carrier.
"Wheel" Display ... |
The background color (medium blue in this example shows that the chamber is at MEDVAC) will show different, progressively lighter blue shades as the pressure rises until at atmosphere it will appear white.
At the bottom of the chamber graphic is a large line connecting to the Mech Pump via the Chamber Rough Valve and at the left side of the graphic there is an even larger line connecting to the Chamber Cryo Pump via the Cryo Gate Valve.
The green hatching area is the position of the shutter within the chamber. Partially visible behind the dark grey of the carrier you can see the opening of the shutter (in this example behind T1).
In this example, Target #1 is active. It is indicated by a red bordered circle that sequences thru a series of color changes to indicate that the target is active. The color changes only indicate that the particular target is selected, wether or not the system is sputtering is shown by the yellow/red POWER ON indicators scattered thru all of the various screens.
One of the unique features of the MVT-8X Series vs. the MVT-94X/90X/64X/60X Series is the ability to co-sputter on two targets at once. Due to the nature of the shutter assembly, co-sputter is only available on targets T1 and T3. When co-sputtering the RF signal power is automatically shared between both targets and the resulting display will be similar to that shown.
During etching operations, the entire carrier will be color coded in the same manner as the targets.
The red dot on the perimeter of the green shutter indicator  is the zero position of the carrier. The zero is the front center of the chamber and is reset every time the chamber cover is closed.
Double clicking on the perimeter of the green shutter indicator commands the carrier to rotate to that position. The selected position will be indicated by a magental colored dot. The carrier will slew (taking the shortest path) until the red zero indicator dot and the magenta commanded position dot agree to within the limits set by the POSNTOL system variable — normally 4°. While the carrier is in motion, the lower portion of the screen will show the current position of the carrier referenced to the zero position (front and center when the chamber was closed) as well as the state of the motor drive command and the nominal RPM of the carrier itself:
The carrier"s position is shown to two decimal places and is accurate to ¾°. The background of this indicator will be rose when the carrier is in motion and straw when the carrier is stopped. If the carrier is stopped at a designated target location, the background will be mint. The RPM value is approximate and is for reference only.
The large dark grey donut with black radial stripes represents the carrier. The spokes are for illustration only and make the carrier rotation more easily noticable from a distance. The lighter grey circle on the carrier labelled S1 is the nominal zero location of the item to be sputtered if operating in index sputter mode.
 The vertical black, green, or yellow bars at the top of the chamber area are the gas inlets. There are two gas inlets, vent gas (usually N2) shown in yellow/black on the left, or the process gas(es) (as per customer specification, typically Argon) shown in green/black on the right. The rectangles will be black filled when the valve is closed and will be color filled when the gas is flowing.
 The process gas can be manually turned on/off by double clicking on the gas indicator LED located directly above the gas setting slider. The setpoint of the gas will be shown numerically in the straw colored rectangle directly below and to the right side of the setting slider (showing the setpoint of 15 mT in this example). The process gas name defaults to GAS1 but can be changed on the Configuration Tab, in this case it has been changed to Argon. The slider allows the process gas target pressure to be set to any value between 0.0 mT and 50.0 mT in 0.1 mT steps. The setpoint is shown in the upper straw colored rectangle below and to the right of the gas setting slider. The lower rectangle shows the actual gas pressure reading value as read from the baratron control. The color of this rectangle will vary as the reading changes. When the reading is rising, the background will be mint colored, when steady, it will be straw colored, and when falling it will be rose colored.
Just to the right of the numerical boxes is the gas gauge and Gas OOS (OOS - Out Of Specification) indicators. The Gas OOS indicator will only come on when the power supply and process gas(es) are commanded on and the gas is out of specification for longer than the GASWAIT interval (nominally 30.0 seconds). The value set in the GASLIMT determines the tolerance band about the commanded setpoint.
The gas setpoint and the tolerance bands are indicated on the Gas Gauge control by a series of thin horizontal lines running the width of the control. The black line indicates the setpoint and the two red lines are the upper and lower tolerance limits. The actual value read from the gas system is displayed as a thick vertical bar occupying the left ¾ of the control. The color of the actual value bar changes depending on it"s relation to the red setpoint tolerance lines. Below the lower setpoint tolerance it will appear red, above the upper it will appear magenta and between the two it will be green as shown in this example. Although unlabelled the range of the gas gauge is from 0.0 mT to 50.0 mT with tick marks every 10.0 mT.
On the upper left portion of the MVT-8X Series Service Tab is the Safety Stack. This indicates the state of the STS (Safe To Start) relay, K1 and it"s associated inputs. When all safety interlocks are met, the stack will appear as shown at right. Due to the series string nature of the safety stack "lower" item states cannot be resolved when a "higher" priority interlock is not met. The interlocks that cannot be determined are then shown with an "unresolved" LED indicator instead of the normal off or on indications. The order of safety precidence is:
- Chamber Vac
- Water Flow
- Safety Cover
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Safety Stack illustrating how loss of water flow masks the state of the "lower" Safety Cover Ok input — shown as black filled indicator... |
The Air Pressure and Chamber Closed indicators, while not part of the safety stack proper, are still needed for proper system operation. Without sufficient air pressure the system can not be sure that the electro-pneumatic-vacuum valves will operate properly. When the Air Pressure input is not met, not only does this indicator go out, but all of the valve indicator LED"s on the DMP (Diagnostic Maintenance Panel) will rapidly flash to show that their operation is not certain.
Directly below the Safety Stack is the Power Status group. This group of indicators and controls is used by the operator to observe the status of the RF (and/or optionally DC) power supplys. Clicking the RF Tuning box will bring up the RF Auto Tune Parameters. These parameters are used to preset the load and tuning capacators for each target and for the etch platform. A separate value is also available for the co-sputter configuration. Double clicking on any of the value boxes on the Load/Tune Parameters panel will alternate between percentage readings and the actual voltages that the percentage readings correspond to. This makes it easy to check for the proper outputs using a voltmeter.
There are additional parameters on the Load/Tune Parameters panel that correspond to the settings from the 94x___ai.txt file (the ___ is the serial number of the specific system). Also on this panel are the VSWR ratio limit, the RF Enable Polarity and the peak RF power supply wattage as read from the PLC. These last three parameters are factory preset but can be field modified if the power supply is changed/upgraded in the future.
The indicators in the Power Group also include:
- Numeric VSWR
- RF VSWR out of Limit Indicator
- RF Power Supply Over Temp Indicator
- RF OK Indicator
- Ramping Indicator
The ramping indicator will also show the power level that is being ramped to when the power level is manually or programmatically set. The manual power controls are located in the lower center region of the screen and appear similar to this:
At the top of this group of controls is the power setpoint slider and the red Set Power button. As a safety feature simply sliding the setpoint slider does NOT change the power supply setting until the red Set Power button has been clicked. This is to prevent an operator from inadvertantly sending the control to full output with a slip of the finger.
For an RF system there are three rectangular graphic areas, one for RF command, one for Forward Power and one for Reverse Power. The RF command area needs special explanation. In the RF command graphic there are two horizontal colored bars, the narrow red "ramping to" value and the wider green "current setting" value. Additionally there are three vertical black bars, the two thick bars correspond to the endpoints of the "ramping to" bar and the "current setting" bar, while the thin vertical bar near the left end corresponds to the factory preset "strike" wattage.
When the power setting is sent to the PLC by clicking on the red Set Power button, the red "ramping to" bar will extend to the new power setting. The green "current setting" bar will slowly adjust itself to meet the red "ramping to" bar at a rate controlled by the settings of the Ramp Rate field on the Configuration Tab. Setting the Ramp Rate value to zero will result in a step change in the output power instead of a smooth ramp.
During the time that between the power setting being changed and the "current setting" bar meeting the "ramping to" bar, the Ramping indicator will be on and the target power will also be shown. For timed sputtering operations, the time required for the ramp to occur is NOT counted as part of the total sputtering time. The sputter time will only start counting once the ramp operation is complete.
Near the center of the screen is the Cold Stack. This group of indicators and controls shows the status of the chamber cryo pump and the chamber vacuum level. This group includes the pump on/off button (interlocked with the mech pump so that the mech pump must be running before the cryo pump can be started) as well as the Cryo Temp indicators, the Med Vac and Hi Vac indicators and the Ion Gauge indicators and control.
The Ion Gauge can be manually selected by double clicking on the IG On indicator. The Ion gauge can also be selected by clicking on the vacuum state indicator located to the right of the chamber "wheel".
Below the cold stack is the Mech Pump Group. This group of controls/indicators allow control of the mech pump and provide both the state of the pump enable signal and of the backpressure valve. The backpressure valve is opened automatically when no other valves are open on the roughing manifold. This valve allows a small amount of the system vent gas (normally N2) to be fed to the mech pump so that it does not over pump it"s internal oil supply and potentially backstream oil vapor into the vacuum system.
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Mech Pump Group showing mech pump command button, pump enable signal indicator (unlabelled) and the Backpressure Valve indicator. The mech pump graphic is colored light blue to correspond with rough vacuum. |
Located directly below the chamber "wheel" are the Target Selector buttons and target lifetime indicators. These buttons selecte the appropriate target (or pair of targets in the case of co-sputter) and strike the target if the system is able to do so.
When a target is selected the selector button will appear red and the appropriate target indicator will appear on the "wheel" portion of the display. The numerical values below the T1, T2, T3, Heat/T4 command buttons show the accumulated power applied to each target since the last time the targets were changed and the values reset on the Configuration Tab. These figures are not meant to be a precise measurement but are more for estimating target lifetime remaining. It is an integral of the targets use factoring in both runtime and power level. It is expressed in kilo-watt-hours (kWH). When co-sputtering on targets T1 and T3 the commanded power level will be divided by two and applied equally to each target.
Below the Target Selector are the four shutter indicators and the vane indicator/control. The four shutter positions imply that the opening in the shutter is located under the associated target. The 5th indicator in the lower left corner of this group shows and controls the status of the vane. The vane is used to cover/expose T2 during certain operations.
By double clicking on this indicator, it becomes the override control for the vane. The shutter position itself is controlled by the Index Shutter pushbutton on the DMP or by the same named button located on the lower right of this tab. While the shutter is in motion the indicator above the Index Shutter button will illuminate. The four amber shutter/target indicators on the DMP will flash rapidly when the shutter is in motion. When the shutter is stopped at a target location the amber LED on the DMP will flash slowly. During the time that the selected target is active the amber LED will remain on steady.
Located on the very bottom of the MVT-8X Series Service Tab is the Spin Control. This control group allows manual continuous rotation at any desired RPM. Additionally it shows the current position of the carrier relative to the zero reference, the state of the motor command output and an approximation of the speed of rotation. The rotational speed is nominally in the 0.1 RPM to 10.0 RPM range in 0.1 RPM steps. However, due to the nature of the system, the RPM value is approximate only but the command settings are precisely repeatable. The displayed RPM value is only approximate and will vary considerably in normal operation. However the command signal is steady and stable no matter what the indicator is showing at any given moment. Due to the lag in the VB response time vs the speed of the PLC, the RPM can only be considered an estimate.
Rotation is initiated by setting the desired RPM and then clicking on the Spin button. The spin button is disabled whenever the RPM setting is zero. Once rotating, the carrier can be stopped by again clicking on the Spin button. The accelleration/decelleration profile of the carrier motor is determined by the motor controller and is factory preset and should never require adjustment. The velocity profile has been adjusted to provide rapid starts/stops consistent with not "flinging" the materials to be sputtered off the carrier. The position indicator reads to 0.01° but the actual position resolution is 500 counts/rotation or 0.72° per step. The zero is re-referenced every time the chamber cover is closed and is automatically set to the front and center position of the carrier.
MVT-8X Series Settings Tab
The MVT-8X Series Settings Tab is where recipes are composed and executed. Whatever the contents of the recipe grid is when the Cook button is pressed is the sequence of actions that will be performed.
The screen is divided into four main regions. Along the top we have the target selector and the parameter setting area. In the middle we have the recipe grid that contains all of the steps in this recipe. There is no practical upper limit to the number of steps in a recipe. The grid area is divided into a series of columns for the various parameters. Those parameters not needed for a specific mode are left blank or filled with a dash (—) character. Along the bottom we have several command option buttons and selectors.
Recipes are executed one step at a time from start to finish in the order shown. The actual recipe file is stored externally as an editable plain ASCII text file with a .rcp extension. The external files can be saved to floppy disk or otherwise copied and can be edited and printed separately. The recipe file internal format is simple and self- explanitory and is detailed in the appendices of this manual.
Physically on the disk the recipe files are stored in one of two directories. The specific directory is determined by the program at startup and is controlled by the state of the Maint Key Switch on the DMP. If the Maint Key Switch is in the ENABLED position the program will automatically select those files found in the c:\maint directory. If the Maint Key Switch is in the DISABLE position when the program is started, the program will only access those recipe files located in the c:\user directory. This allows management control over recipies being developed. As the engineering staff refines a recipe it will usually reside in the c:\maint directory. Once the recipe has been certified for use by production, the Maint Key Switch is removed and the recipes placed into the c:\user directory. Recipe editing is also supressed when the Maint Key Switch is in the DISABLE position.
Assuming that editing is allowed the following command options are available:
- Pre-Sputter on T1, T2, or T3
- Rotary Sputter on T1, T2, T3
- Stationary Etch
- Indexed Sputter on T1, T2, or T3
- Rotary Co-sputter on T1 and T3
- Rotary Heat
- Wait for HiVac
- Pause
- Vent & Stop
All of the modes are timed. For those steps with rotation, the time specified is automatically extended to complete the last full rotation. This insures that when rotary sputter is used that the entire carrier area receives the same exposure for best uniformity.
All RF sputter modes include target specific ramp rates so that composition targets can be brought up to full power gradually and not suffer severe thermal shock or expansion due to a large power step. The ramp rates are set by the Configuration Tab (covered elsewhere) and are applied automatically when the targets are selected. The time spent ramping is not part of the active sputter time.
If you examine the target selector, there are four index stations. Heat, T1, T2, and T3. When no target is selected, etching is implied. As each target is selected by clicking within it"s area on the Select Target(s) graphic it will change color between red (selected) and grey (not selected). The targets are automatically interlocked to prevent selection of unsupported configurations.
For example any of the three targets and heat can be individually selected, however both T1 and T3 can be selected at once to specify co-sputter.
The parameter area of the MVT-8X Series Settings Tab contains four slider controls and a text entry field. There is also an Est. Reps field that displays the estimated number of rotations of the carrier based on the RPM and time. The four sliders are for:
- Power — 0W to Full Rated output (normally 3kW)
- Process Gas — 0.0 mT to 50.0 mT in 0.1 mT steps
- RPM — 0.1 RPM to 10.0 RPM in 0.1 RPM steps
- Elapsed time — one second to twenty-four hours in one minute increments with a fine adjustment of +-1 minute in one second increments using the up and down arrows adjacent to the Time text field.
The text field is used to append a comment to the step in the recipe.
All of the slider controls have large and small increments. The large increment is done with the mouse or with the <Pg Up> and <Pg Dn> keys. Small increments are performed with the <Left Arrow> and <Right Arrow> keys.
Depending on the sputter mode selected the RPM indicator"s minimum in the parameter area will adjust itself to 0.0 RPM (implying index sputter) or 0.1 RPM (implying rotary sputter).
For targets T1, T2, and T3 as well as cosputter, the Presputter box can be checked to allow for target conditioning prior to actually performing the sputter operation. In presputter mode the target is occulted by the shutter for the duration of the step. This allows the targets to burn off any oxidation or contamination without placing any of the material onto the items being sputtered. Once the presputter has been performed, you would normally specify a "normal" sputter operation on the same target to actually coat the material in process.
Once the target has been selected and the parameters specified clicking on the Add button will add that process step to the recipe. The step and all of the needed parameters will appear in the grid.
Once a step has been added to the recipe grid it should be checked for accuracy. If there is an error in the step single clicking on it will generate a dialog that allows deletion of the step.
Many users find that a good start to any recipe is a Wait for HiVac step. This can also be useful between sputtering on two different targets or after a heat step. This insures that the minimum of particulates are in the chamber after each sputter/heat/etch operation or to clear the chamber of any reactant or out gases.
Another option is that the user may wish to program a delay between sputter steps. This gives the material being sputtered time to cool and stabilize between steps. A pause is specified by using the slider control to select the time for the pause. The slider allows setting the pause interval from 00:00:00 (no pause) to 01:00:00 (one hour) in 1 second intervals. The pause button itself will only enable when the pause time is not zero.
Due to it"s nature, a Vent and Stop step can ONLY occur as the last step of a recipe. Once this button has been selected no more steps may be added to a recipe and the other command option buttons will be disabled. A Vent and Stop IS optional however, there is no requirement that any recipe have one. This is often useful for developing new recipies and for testing as sequences can be developed and debugged without having to vent and pump down every time.
Here we have an example of a complex recipe that includes waiting for hivac, presputter, sputter, pauses and finally a vent:
Once a recipe has been created the operator should return to the main Recipe Tab and save the recipe to disk.
MVT-8X Series Runtime Tab
The MVT-8X Series Runtime Tab is only visible while a recipe is in-process. During the run of the recipe, the other tabs in the program are disabled. When a recipe is NOT running, this tab is disabled and cannot be selected.
The MVT-8X Series Runtime Tab is much like the MVT-8X Series Service Tab but with all operator inputs disabled. In the bottom portion of the screen there are recipe status and logging areas as well as the only active operator control, the E-Stop button. Clicking E-Stop or any internally detected process fault (target quench, loss of gas, STS failure, etc) will eventually return to the MVT-8X Series Service Tab. When a process has successfully completed the recipe the program will return to the main Recipe Tab where the recipe can be rerun without needing to reload the recipe.
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