Chapter 6.23

AMST Molecular Vapor Deposition System MVD100

(AMST)

1.0         Title

AMST Molecular Vapor Deposition System MVD100

2.0         Purpose

ASMT MVD100 is a microprocessor controlled molecular vapor deposition system that can deposit single layer mono-molecular films or multi layer films by sequential deposition of more than one monolayer. Monolayer deposition is used to change the surface properties of MEMS and BioMEMS structures. Sample applications are:

1)       Deposition of a fluorinated organosilane monolayer (FOTS) to increase surface hydrophobicity and decrease friction and wear of moving MEMS parts; and

2)       Deposition of organosilane monolayers with reactive head groups to enable covalent attachment of specific receptor molecules to BioMEMS sensor surfaces.

There are three independent chemical delivery lines available. Labmembers can request addition of new chemicals after review with staff. The equipment header file lists the presently connected chemicals.

The AMST tool has further been augmented with a VUV (Very Ultra Violet) lamp assembly (see Figure 2 ) that has been mounted to the modified MVD lid. The Xe-filled dielectric barrier discharge excimer lamp in the assembly (refer to Figure 2) has an emission wavelength of 172 nm. when the custom power supply to the lamp is ON. Some applications for the lamp assembly include, but are not limited to:

(a)     Low temperature nano-skin oxide formation,

(b)     Low temp polymer curing,

(c)     Surface treatment enhancement to promote low temp si-si wafer bonding.

Further process applications are possible. Please contact Bill Flounders or Matthew Wasilik to initiate / discuss new or standard applications..

 

3.0         Scope

This manual describes the operational procedures and user level trouble shooting guides of the ASMT. Please refer to the equipment manual (Office has a copy), provided by the vendor, for chemical/DI wafer refills and other maintenance issues.

4.0         Applicable Documents

Revision History

4.1         MVD 100 System Document for Berkeley (Copy in Office), Applied MicroStructures, Inc., San Jose, CA, 7/29/2004.

4.2         Material Safety Data Sheets for FOTS, DDMS, APTMS (Copies in Office and Lobby).

4.3         Gelest Chemicals Catalog #3000-A

5.0         Definitions & Process Terminology

5.1         Molecular Vapor-Phase Monolayer Deposition: A self-limiting chemical process that coats a monolayer of film (one molecule thick) on the substrate surface.

5.2         RF Plasma treatment: MVD 100 uses oxygen plasma to clean and pre-treat the substrate surface before coating.

5.3         Vapor Injection: The precursor chemical vapor is first stored in an expansion chamber to a prescribed pressure. When the expansion chamber reaches the desired pressure, the chemical source is closed and then a separate valve is opened which connects the vapor in the expansion chamber with the evacuated process chamber. This sudden pressure equilibration, ‘injects’ the vapor into the evacuated process chamber.

6.0         Safety

6.1         Follow all the Microlab general safety rules.

6.2         RF Hazard: The system uses RF power to generate plasma for chamber cleaning and substrate pre-treatment.

6.3         Chemical Hazard: Do not vent the chamber before purging process finishes. Report on WAND immediately if suspect there is a vapor leak. Some chemicals used in the system are flammable and toxic.

6.4         Emergency shut down: In case of emergency, shut down the whole system by pressing the red emergency button.

7.0         Statistical/Process Data

7.1         Equipment Enable Message.

7.2         Program and Comment sections from other lab members on the WAND.

7.3         New chemical degas procedure located in the AMST on-line maintenance manual.

8.0         Available Processes, Gases, Process Notes

Available Processes

8.1         FOTS coating: The film thickness is 13 Å and the contact angle (DI Water) specification is 110° ± 2°.

8.2         DDMS coating. DDMS = dimethyldichlorosilane Gelest Chemicals (Prod #SID4120.1) Contact angle (DI Water) specification is 103°±2°. DDMS has been tested previously on the system and there is a vendor provided recipe available.

8.3         APTMS coating: The film thickness is 5 Å and the contact angle (DI Water) specification is 35 ± 2. APTMS recipe has been developed by Lab member. Note APTMS and DDMS processes can not be used simultaneously.

8.4         APTS coating. Among other uses, this process may serve as an adhesion layer for polyimide on silicon substrate. MVD of APTS supplants the standard polyimide wet surface treatment process, with typical superior results. Contact staff for details.

VUV Lamp Assembly

8.5         The VUV (Very Ultra Violet) lamp assembly includes a Suprasil port in the MVD lid, and a delicate, 172nm emission custom low profile lamp. The lamp itself is encased between two insulating UHMW PE components white in color (refer to Figure 1). Note that *ANY* or *ALL* of the components could easily be broken if the MVD lid is not handled carefully. DO NOT slam the lid down before pumping chamber. DO NOT jerk the lid open after venting. Use caution when opening or closing lid! 

Some potential applications for the VUV lamp include:

·         Low temperature “nano-skin” oxide deposition using TEOS precursor. Multi-substrate compatible,

·         Low temp polymer curing

·         Surface treatment for low temperature silicon-silicon fusion bonding

This manual will be updated as the characterization/experimentation with such applications progresses, Please contact Bill Flounders or Matthew Wasilik for details.

8.6         Potential applications with the VUV assembly include low temperature oxide formation, low temp polymer curing, and low temperature silicon-silicon fusion bonding. This manual will be updated as the characterization/experimentation with such applications progresses, please contact Matthew Wasilik for details.

Available Gases

8.7         Line 1 is dedicated to deionized water vapor. A small amount of water vapor is required for reaction of most chlorinated or oxy silanes to react with silica surfaces. AMST uses one of the chemical delivery lines to meter in specific amounts of water vapor and control the reaction of the surface with the vapor precursor. No other chemicals may be connected to Line1

8.8         Line 2 is available for labmembers proposed chemistries. New chemical requests must be reviewed with Microlab staff. See Bill Flounders to discuss any new chemical requests. (bill@eecs.berkeley.edu). To date, DDMS (Gelest Prod #SID4120.1); APTMS Gelest Prod #SIA0611.0 CAS [13822-56-5]; and 11-acetoxy-undecyltrichlorosilane (Gelest Prod# SIA0114.0) have been connected on Line2. The AMST enable message will list the chemical presently listed to Line 2. There is a detailed procedure described in Section 10 to request chemical changes to Line 2.

8.9         Line 3 is dedicated to FOTS: Fluor octyl trichloro silane. Formal name is Trichloro-1H, 1H, 2H, 2H-perfluorooctylsilane. Gelest Chemicals (Prod #SIT8174.0) CAS [78560-45-9] No other chemicals may be connected to Line3.

8.10      Oxygen: Used for substrate surface condition and chamber cleaning.

Process Notes

8.11      Samples with photo-resist or other patterned organic layers are allowed in the system but members should be aware that the oxygen plasma preclean conditions are identical to a plasma photoresist stripping process and will strip a significant amount of photoresist or any other organic thin film. The tool is not to be used as a stripping tool since chamber temperature is not hot enough to prevent build up of organic residue in the chamber. 

8.12      The process chamber can accommodate one 6” or one 4” wafer at a time. Many small samples can be loaded at a time. The coating is primarily to the top side of the sample. Results indicate some coating does reach the backside of samples depending upon the sample roughness. Backside coatings are not uniform.

8.13      The system hardware setup allows three types of process sequences: 1) single layer, = one layer deposition 2) dual layer, = 2 sequential layers; the first layer information is defined by the single layer process; 3) multi-layer = a combination of single layer process followed by second layer of the dual layer process. NOTE – these processes are not mutually exclusive but are specifically shared. For example, the dual layer process can deposit two layers sequentially. The first layer will use the recipe information of the single layer process; the second layer is defined in the second layer section of the dual layer recipe. If you change the recipe settings of the first layer in your dual layer recipe – you have also changed the recipe of the single layer process. The multi layer process allows the user to run the first and second layer recipes multiple times. If you change the recipe settings in the multi layer process – you have also changed the single layer and dual layer process. Be sure to discuss this issue with the superuser during your qualification.

8.14      Presently, the single layer sequence is setup for FOTS coating.

8.15      The multi layer process (with 0 cycles of layer 1, and 1 cycle of layer 2) is used to deposit a single layer of whatever chemical is presently connected to Line #2. To date DDMS and APTMS have been tested on Line #2. See the equipment enable message for a list of the presently connected chemicals.

8.16      There are six round buttons on the right side of the display panel (out side of the panel). They have been labeled: [System], [F1-5]. These buttons are for PLC programming when logging in as maintenance or administrator. If you accidentally activate the buttons, press [System], then [F1] to return to the system display page.

9.0         Equipment Operation

9.1         System Description

The system uses a PLC (Programmable Logic Controller) to automatically control all the operations, except sample loading/unloading. The user can issue commands by touching the buttons on the system’s touch-screen display. There are two kinds of buttons: square buttons for switching between display pages, round buttons for starting a command sequence (recipe) or a system routine. When a round button is green, it means the sequence/routine is available for use. When it is purple, the sequence/routine is being executed. The system can only execute one sequence/routine at a time.

9.2         Display Pages

9.2.1          Login Page: AMST Qualified lab members are allowed to log into the system on level one security, which allows viewing all the recipes and executing most of the process sequences and system routines. AMST qualified members must see superuser or staff to change recipe settings The password for Level1 access is [1,2,3]

9.2.2          Login Page: Superusers may log in to the system at level two security. Level 2 allows recipe changes and modifications. Password for Level 2 will be provided to superusers by staff. Maintenance and Admin login are reserved for staff access.

9.2.3          System Status Page: This page shows the status of all components of the system. The component that shows purple color is activated. There are two buttons, Abort and Clear Fault, on the right upper corner of the page. The user can stop any routine or process sequence by touching the Abort button at any time.

9.2.4          Main Page: This page has three buttons: [Sequences], [Routines], and [Logout].

9.2.5          Sequences Page: From this page, the user can select and run, or view the steps and setting of a process sequence.

9.2.6          Routines Page: From this page, the user can select and run 5 system routines: [pump down], [vent], [purge], [RF clean], and [leak check].

9.3         Pre-Deposition Checks

9.3.1          Enable AMST on the WAND and log into the system.

9.3.2          On the System Status Page, check the chamber pressure. If the chamber pressure is over 100 mtorr, go to the Routines Page, and run [purge] routine. Then run [leak check] routine. If the leak rate is over 5 mtorr/min, do not use the tool. Report the problem on WAND.

9.3.3          Check Nitrogen flow to the dry pump (20-30 L/min), and make sure that water is flowing to the pump (red on gauge).

9.3.4          Check the line pressure of the coating sequence planned to use. Line2, for DDMS, should be less than 0.5 torr; Line 2 for APTMS should be less than 0.3 torr; Line3, for FOTS, should be less than 0.1 torr. If the pressure is over the limits, do a dummy process run first.

9.4         Processing A Run

9.4.1          On the Routines Page, run [vent] routine. Wait till the system displays the message “Chamber is Vented”.

9.4.2          Open the process chamber door carefully! DO NOT jerk the door open, as expensive components inside the VUV assembly are fragile. Check the cleanness of the chamber. See Trouble Shooting Guidelines if the chamber is not clean.  Always wear a clean pair of poly gloves when handling anything in the process chamber.

9.4.3          Load wafer/samples into the process chamber. Close the chamber door carefully! DO NOT slam the door, as expensive custom components inside the VUV assembly are fragile.

9.4.4          On the Sequences Page, touch the corresponding button to run the selected process sequence: Single Layer Sequence for FOTS, and Multi-Layer Sequence for APTMS.

9.4.5          The sequence starts with a purge cycle, followed by RF treatment, vapor injection, process reaction, and final purge cycles. It takes about 25 minutes.

9.4.6          When the process finishes, run [vent] routine. After the chamber is vented, open the chamber door, and remove the coated wafer/samples.

9.5         Log out of The System

9.5.1          Make sure the process chamber door is closed. Run [pump down] routine. Check that the chamber pressure is blow 50 mtorr.

9.5.2          Log out the system by touching the [Logout] button on the Main Page. Disable AMST on the WAND.

10.0      Troubleshooting Guidelines

10.1      Problem:       The display panel shows a PLC page, other than any system pages describe above.

Cause:          Some one activated the [System] or [F-5] hardware buttons on the right side of the display panel.

         Solution:       Press [System], then [F1] button to return to the system display page

10.2   Problem:       Display is too dark to see.

         Cause:          Same as the cause of above section.

         Solution:       Press [System], then [F2] button to turn up the display brightness.

10.3   Problem:       Process vapor cannot reach injection pressure.

         Cause:          The process chemical cylinder is empty.

         Solution:       Report the problem on WAND.

10.4   Problem:       The system displays the RF failure alarm.

         Cause:          Previous user’s sample differs from yours. The RF system needs more time to tune.

         Solution:       Clear the alarm and abort the sequence. Restart the sequence, the RF system should be able to tune. If problem repeats, report on WAND.

10.5   Problem:       You would like to change the line 2 chemical from what is presently connected to another, already approved chemical.

10.5.1            Only Microlab staff and AMST Superusers can change AMST chemicals

10.5.2            Superusers must report a problem to AMST 1-day in advance of planned chemical change. In the problem report define the chemical you plan to install on Line 2.

10.5.3            The next day, the AMST technician will isolate the tool from the line2 source, remove the chemical presently loaded in the line2 cylinder and dispose in the lab organic waste. If members have high value chemicals they would like to preserve, state this in the problem report when you request chemical change. The tool will be left with line 2 manual valve closed, line 2 heated to 80C, chamber heated to 50ºC, both line 2 autovalves open, and chamber open to the pump. An N2 purge line will be added  to the tool and when available, N2 purge gas will be left flowing on Line2 after chemical disconnect. The AMST technician will update the AMST enable message and enter the chemical name you provided in the problem report as the new compound connected to AMST Line 2.

10.5.4            Empty cylinders will be thoroughly rinsed with isopropanol and returned to the AMST parts drawer. Report a problem if you note corrosion of any of the source cylinders.

10.5.5            At least two hours purge time is recommended, after which Superusers will load chemicals in a clean source cylinder, connect to the tool, follow the chemical degas procedure and proceed with their process. Send email to amst@silicon confirming that the new compound has been added to Line2 and (if available) provide recommended process settings for that compound.

10.6            To restart AMST after power off at wall panel, power off at EMO switch or power off due to loss of power, follow steps below:

10.6.1            Prep

10.6.1.1       Locate AC distribution box inside front right access door at bottom.

10.6.1.2       Switch all sub breakers to OFF.

10.6.1.3       Switch main breaker to off.

10.6.1.4       Turn EMO mushroom switch cw to bring switch up.

10.6.2            PowerUp

10.6.2.1       Switch breaker at wall panel to ON.

10.6.2.2       Switch main breaker (right most) of AC distribution box ON (up).

10.6.2.3       Push in green power switch at far right of AC dist box.
Note white LED below green button now illuminated.

10.6.2.4       Switch PC sub breaker to ON.

10.6.2.5       Switch controller sub breaker to ON.

10.6.2.6       Switch supply and chamber heaters to ON.

Notes:

·         Pump sub breaker is not active since AMST pump is wired directly to independent breaker at AMST wall panel.

·         After restart all valves will be in closed position.

·         All system constants are stored and should not be lost due to power loss.

·         After restart, all heaters need to be restarted from heater control page.

11.0      Figures & Schematics

Figure 1 - Complete AMST System Schematic

A specified amount of precursor is introduced into the main chamber via expansion chambers. The surface layer formed upon the substrate may then further be modified with VUV irradiation as the application necessitates.

Figure 2 - VUV Lamp Assembly Schematic

The components comprising this system are custom fabricated, and thus very expensive. Use care when opening or closing MVD lid.

Figure 3 - VUV Dielectric Barrier Discharge Xe Lamp Detail

12.0   Appendices

12.1      First Layer Recipe  - Vendor Provided FOTS Process Conditions. As written below will use chemical from Line 3 + DI water. Note Line 2 not used (vapor order = 0). Also note that the relatively high H20 pressure of 4 Torr is always the last step (vapor order = 2). This minimizes risk of the chamber gas mixture flowing back into expansion chamber and contaminating the line.

1st Layer

 

 

 

 

 

RF

O2 Flow

100

Power

200

Time

300

 

(sccm)

 

(W)

 

(seconds)

 

 

 

 

 

 

 

 

Vapor Order

 

 

 

 

 

 

1st

2

2nd

0

3rd

1