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AMT 8100 Plasma Etcher, amtetcher

The Applied Materials Technologies 8100 Hexode plasma etcher.

Picture and Location

 AMT 8100 Plasma Etcher

AMT 8100 Plasma Etcher

 

Background

 The AMT 8100 etcher has been in constant use since it was installed in the lab in 1986.  A regular workhorse of a tool it can etch 24 wafers at a time making it a popular machine for low power REI oxide, nitride and Si etching.  It is also used to the creation of ASML zero level alignment marks.

Process Capabilities (Cleanliness, Materials, Performance)

 

Function

Reactive Ion Etcher for Oxides or Nitrides.  Also can be used for Si trench etching.

 

Overview

  • Fluorine based etch chemistry.
  • 4 inch wafer ONLY.
  • Reactive Ion Etcher.

 

Special Notes or Restrictions

  • This machine allows non-metal and standard metal (from gyphon sputterer only) material.  Other materials may be authorized on a case-by-case basis.  See staff.
  • Semi-clean tool.  See Material section of our website for details.
  • Check Etch Rate Chart for details on programs and etch rates for various thin films.

 

Contact List and How to Become a User

 The following people are responsible for the etcher;

  • Process and training; Nancy  For training please see the Training Calendar for scheduled trainings.
  • Maintenance; Elmer,  Mike Dickey
  • Superusers; to be determined

Operating Procedures

 

General Information


Pre-treatments

To prevent resist burning, wafers should get 15 minutes UV Bake and 30 minutes at 110C oven bake. This applies to 3612 and 955 resists only. The SPR220 resist at 3 or 7 um will not be helped by this procedure. The thicker resists will burn in the amtetcher.

 

Post-treatments after oxide and nitride etch processes

Wafers need a plasma polymer cleanup step, even if they are going into a H2SO4/H2O2 strip/clean. This is especially important after a contact etch, where the CHF3 flow is high and the O2 flow is low. A common cleanup process is one done in drytek2, using CF4 for 15 seconds. This process has the advantage that it removes the polymer/oxide layers at the contact bottoms along with a  hundred angstroms of damaged silicon. However, it does not remove the thick sidewall polymer. A hot H2SO4/H2O2 clean after the short plasma cleanup will remove the sidewall polymer. If you are not worried about leaving a little silicon damage, a short O2 plasma in either drytek2 (use the descum recipe) or the gasonics can be used instead of the CF4 plasma. A long gasonics O2 resist strip will most likely remove the sidewall polymer, but such a process has not been qualified. For via etching which stops on metals, the via etch process with its high O2 flow should be used since the sidewall polymer is much thinner.

 

Gas Information

#1 O2 -- max flow 50 sccm [size (N2) = 50 -- correction factor = 1.0]
#2 CHF3 -- max flow 150 sccm [size (N2) =300 -- correction factor = 0.5]
#3 SF6 -- max flow 78 sccm [size (N2) = 300 -- correction factor = 0.26]
#4 Ar -- max flow 71 sccm [size (N2) = 50 -- correction factor =1.42]
#4 CO2 -- max flow 37 sccm [size (N2) = 50 -- correction factor = 0.74]
#5 NF3 -- max flow 48 sccm [size (N2) = 100 -- correction factor = 0.48]

 

Potential Hazards

Although the AMT Etcher can be operated in a safe manner if appropriate procedures and safety precautions are followed, it is important to realize that there are a number of potential hazards associated with the operation and maintenance of this equipment.

High Voltage: Care should be taken whenever any internal components or wiring are exposed. Always turn off the main power circuit breaker on the system when doing any procedure that involves high voltages in the work area.  

Hot Components: Some reactor parts become hot during normal operation. Care should be taken to avoid touching these components during operation and maintenance procedures.  

Gases: The gases used for oxide etching are simple forms of fluorocarbons and oxygen. Although generally nontoxic, these gases should be handled with the same care reserved for laboratory gases in general. Because plasma etch reaction products are often complex and unknown, the system exhaust plumbing should be treated with caution. Any unusual smells should be reported immediately to either maintenance or processing technicians.  


Emergency Shut-Down Procedures

In the event of an emergency, the AMT Etcher should be shut down by:

  • Most minor emergency, or suspected machine malfunctions can be best handled by putting the etcher into “Service Mode” on the mode select section of the front panel and then pushing the 'Equip Off' button. This will activate the power down sequence.
  • In the event of a major emergency, or one of unknown severity, use the red button marked “Emergency Off”. This is the EPO (Emergency Power Off) button to the machine. You are asked to use good judgment in using this button because the machine loses the contents of the internal memory when it is activated. Re-programming must be done by a technician by hand. By all means, however, if there is a doubt in your mind as to the severity of an emergency, use the EOP button!

 

Operating Instructions

  • Enable “AMTETCHER”.

 

Standby Conditions

  • You should find the bell jar pumped down with program is running.
  • HOLDING NN:NN:NN”  "Step 5 Ready' message on the screen.

 

End Pump Process

  • Press “Run” button to clear the message on the screen.
  • Press “Abort” to end process 2.
  • A “PROGRAM 2 IS READY” message on the screen.
  • Press “Vent” to vent the chamber.
  • When the system is vented, an alarm will sound and a message appears on the screen “System Vented”. Press “Alarm Silence”.


System Inspection

  • Press “Bell Up” buttons at the same time, do not let go on the button until the bell jar is all the way up.
  • Follow the inspection list and inspecting each item carefully. Report it if any problem is found.
    • Hoist bell jar smoothly and quietly. Check all the tray latches and make sure they do not protrude about the top surface of the hex (they may up to 1 mm maximum below flush).
    • Check that Ardel overlays show no signs of cracking or arcing/burning, especially around the latch assembly and the bottom corners.
    • Unlatch each tray, tip it outward, and inspect the aluminum tray in the latch area for signs of arcing.
    • Reinstall each tray by push in firmly on the top of the tray while pushing down on the outside corner of the latch. At the same time, this will help make the latch flush.
    • Make sure each tray is TIGHT! When push in firmly at the top of each tray, there must be NO MOVEMENT.
    • Check the hexode rotates and aligns properly, and make no abnormal noise.
    • Check the quartz top disc shows NO signs of arcing or burning.
    • Check the bell jar liners, base plate, and ground ring have an even coating of polymer with no areas of excessive polymer buildup.
  • Press “Bell Down” buttons at the same time, do not let go on the button until the bell jar is all the way down.
  • Use Coral to report any problem or significant etch rate change.
  • After the process is done, make sure you do the inspection checklist again. You want to make sure you are leaving the machine in the same condition you found it.

 

Please Remember

  • Before loading your process wafers, you must condition the chamber by running the process you want to run for 15 minutes.
  • DO NOT change program  2.
  • For program 3, change the process time ONLY.
  • O2 and CHF3 form a polymer (at ~50 angstroms/min), which needs to be removed in the Gasonics or Drytek2 using the Polymer Clean-up or Contact Clean-up recipes. NOTE: Sulfuric/Peroxide is not enough!
  • Make sure the wafer flats are NOT in the same place as the wafer attachment clips.

 

Select and Edit Etch Process

  • Press "Process Select" button to select the process you want to run.
    • Process 1 is used by the technicians for cleaning the system.
    • Process 2 is the Pump down, clean and condition process (Stand By).
    • Process 3 is the standard Oxide Etch process.
    • Process 4 is the Via Etch (ASML alignment target etch) process.
    • Process 5 is the Etch Back process.
  • Push “Mode Select” until “Program” mode is selected.
  • System will ask you to “Load Program Key?”
  • Press “1234” to load the program key.
  • System will ask “Program #?
  • Type in the process number and then press, “YES” to confirm.
  • After confirmed, system will ask you “Delete Program?” press “NO
  • After press “NO”, system will ask you to change the “Etch Times Only?” press “YES” if you want to change the etch times or “NO” if you want to edit the program.
  • Step through the selected programs parameters by pressing, “YES” if the step is correct or “NO” if the step needs to be changed.
  • If “NO” is pressed, you may need to enter the correct parameter and press “YES” to enter it.

 

Copy Other Process Into Process #5- please copy nonstandard recipes into Process #5

  • Press "Process Select" button until Process 5 is selected.
  • Push “Mode Select” until “Program” mode is selected.
  • Load Program Key?” will show up on the screen. Press “1234” to load the program key.
  • System will ask “Program #?”
  • Type in the process #5 and then press, “YES” to confirm.
  • After confirmed, system will ask you “Delete Program?” press “YES”, system will ask you “Copy Another Program?”
  • After press “YES”, enter the process number you want to copy into process 5 then press “YES” to confirm.
  • System will ask you “Copy Another Program?” for the next step. Press “NO
  • Overetch?” Press “YES
  • End of program?” Press “YES”.

 

Review Selected Process

  • Press “Mode select” to “Review” mode.
  • Enter the process number to want to review. (Ex. Process # 3).
  • Step though the selected programs parameters by press, “Yes” after each part of the process is displayed.
  • Note any changes you want to make. (Listed below is program 3 – correct version)
    • Cryo Pump (N)
    • Base = .80 Mtorr (Y)
    • Warm Vent (Y)
    • Cool Step (Y)
    • Flow 1 = 6cc (Y)
    • Flow 2 = 85 (Y)
    • Servo Pressure (Y)
    • Press = 40 Mtorr (Y)     
    • DC Bias = -530V (Y)
    • Max RF = 1600W (Y)
    • Time = 15.0 min (Y) (seasoning time)
    • Overetch = 0% (Y)
    • End of Program (Y)

Seasoning the chamber

  • Run the process you have selected for 15 minutes before process any wafers.
  • After reviewing the process, press “Mode Select” to switch back to normal and press “Run” to start the process.
  • Monitor for any signs of arcing and abort the program if arcing is seen. Contact maintenance immediately and enter shutdown the system on Coral.
  • Monitor the parameters by pressing Pressure, Flow, Temperature, and Power buttons.
  • The alarm wills turn on when the process ends. Press “Alarm Silence”.
  • Press “Vent” to vent the chamber.
  • The alarm wills turn on again when the system is vented. Press “Alarm Silence”.
  • Press “Bell Up” to open the chamber.
  • Inspect the chamber carefully again follow by the inspection list.

 

Etch Wafers

  • Run a test wafer first to determine the etch rates. Calculate the time needed and etch the rest of the wafers.
  • Remove the dummy and load your wafers. (All trays must have wafers in the position).
  • Press “Bell Down” to close the chamber.
  • Use Review mode to check the etch time is correct.
  • Press “Run” to start process.

 

Shutdown procedure

  • When process is done, remove your wafers and replace with dummy wafers.
  • Inspect the chamber carefully again follow by the inspection list.
  • Press “Process Select” to select process #2 (Pump Program).
  • Disable “AMT”.
  • The pump/clean/condition program takes about 20 minutes to complete. An alarm will sound when the program is finished.

 

Training Checklist

Amtetcher Training Checklist

 

 

  • Know which cleanliness group the tool belongs to.

 

  • Know what materials may be etched in the tool.

 

  • Know when to choose the amtetcher over other etch tools (for example, SiN on Si vs SiN on SiO2)

 

  • Understand Pre and Post treatments for resist hardening and removal.

 

  • Understand the difference between Process Select and Mode Select options.

 

  • Know how to review a recipe.

 

  • Know the Program Key (password).

 

  • Know how to change the etch time of a recipe.

 

  • Be able to copy a recipe from memory to Process.

 

  • Be able to change from the stand-by recipe to the desired recipe.

 

  • Be able to lift the bell jar up and down.

 

  • Know how to check for arcing on the hex assembly.

 

  • Be able to remove and replace the wafer trays in a manner that will avoid arcing.

 

  • Be able to unload the dummy wafers and load the device wafers using either the vacuum wand or tweezers.

 

  • Be able to use the wafer loader.

 

  • Know when to season the chamber.

 

  • Know how to start or stop and etch.

 

  • Be able to monitor etching parameters; pressure, gas flows, temp and power.

 

  • Know how to vent the tool.

 

  • Understand how to use the nanospec to check the etch depth and establish the etch rate.

 

  • Know how to put the etcher into stand-by.

 

 

 

Interlocks and Safety Features

The AMT Etcher is equipped with very few interlocks and safety features to protect personnel from the hazards described above. It is important to bear in mind, however, that no system is entirely fool-proof -- there is no substitute for a thorough understanding of the operating procedures, maintenance procedures, potential hazards, and safety procedures associated with this piece of equipment.

  1. Equip. On button will turn on all the subsystems and does a cursory diagnosis to verify correct operation of the subsystems. If any fail this check, the reactor will automatically shut down, sound the alarm silence and post a warning message. If there a multiple failures, the next error message will show when the present one has been fixed.
  2. The Bell Jar has various interlocks that prevent it from being opened until atmospheric pressure has been reached.
  3. The operator may open the bell jar by means of a “dead man switch” which requires the use of both hands to press the “Bell Jar Up” buttons.
  4. A sensor notes the open bell jar condition and the system controller disables the vacuum, gas and RF systems.

 

Facilities

The facilities requirements of the AMT Etcher are as follows:

  • exhsc-f16 Exhaust Scrubbed
  • hev-f8  House Equipment Vacuum
  • hn2-f1 House Nitrogen
  • ho2-f2 House Oxygen
  • nf3-1-f65 Nitrogen Trifluoride #1
  • ofa-f6 Oil Free Compressed Air
  • pcw-f10 Process Chilled Water

 

Facilities not required unless used:

  • c2f6-f50 Halocarbon116 (C2F6) Tank
  • cf4-f53 Halocarbon14 (CF4) Tank
  • chf3-f52  Halocarbon23 (CHF3) Tank
  • har-f4  Argon
  • he-f48  Helium Tank
  • sf6-f49 Sulfur Hexafluoride (SF6) Tank

 

Process Monitoring and Machine Qualification


Instructions for Amtetcher Oxide Etch Quick Check Qualification

 

Purpose

To provide verification and trend of the oxide program including etch rates of thermal oxide and photoresist, selectivity of those materials, and wafer-to-wafer and within-a-wafer uniformity of etch.

 

Frequency of the test

To be completed after maintenance such as cleaning or gas line replacement or on a set schedule to be determined or as needed based on user feedback.

 

Documentation of results

To be posted in the equipment archive for amtetcher on the SNF website and in a file or webpage available to users in data or chart format.

 

Procedure

  1. Use wafers with at least 900A thermal oxide, no pattern.  Patterned wafers may be used to measure photoresist etch rates, too.
  2. Season the chamber for 10 minutes using Program 3.  Be sure to check the program parameters before starting.
  3. Measure oxide and photoresist thickness using one of the Nanospecs.  Be sure to use reference wafer before testing to calibrate the tool.  Take readings for the Center, Top, Flat, Right and Left positions of the wafer.  Readings should be taken about 15mm from the edge.  See Fig. 2.
  4. Place two wafers into tray #1 in positions 2 and 3.  See Fig. 1.
  5. Etch for 2 minutes using the standard oxide etch program, #3.  Monitor gas flows, RF power and bias and record on Monitor Log Form.
  6. Measure oxide and photoresist thickness using the same Nanospec.  Be sure to use reference wafer before testing to calibrate the tool.  Take readings for the Center, Top, Flat, Right and Left positions of the wafer.  Readings should be taken in roughly the same place as the first measurements.  See Fig. 2.
  7. Record results on the Monitor Log.  Record results in data file to get wafer-to-wafer and within-a-wafer
    1. Subtract the second average reading from the first average reading for oxide and for photoresist to get total material etched
    2. To get the etch rate per minute divide the average total material etched measurements by 2. 
    3. To get the selectivity for oxide vs photoresist divide the oxide etch rate by the photoresist etch rate
  8. Record etch rates and selectivity on Badger as a comment and the labmembers wiki.

 

Fig. 1. Place wafers in the two middle positions, flats down.

 

Fig. 2. Nanospec readings should be made in the above positions and recorded on the log sheet.

 

 

 

Instructions for Amtetcher Multi-Thin Film Qualification

 

Purpose

To provide verification and trends of the oxide program including etch rates of thermal oxide, undoped LTO, nitride, photoresist and poly and single crystal silicon, selectivity of those materials, and wafer-to-wafer and within-a-wafer uniformity of etch.

 

Frequency of the test

To be completed after major maintenance such as vacuum repair or gas flow adjustment or on a set schedule such as quarterly or as needed based on user feedback.

 

Documentation of results

To be posted on the labmembers wiki, posted in the equipment archive for amtetcher on Badger, and in a file or webpage available to users in data or chart format.

 

Procedure

  1. Six wafers of the following types; 1)Thermal Oxide- at least 900A thick, 2) Undoped LTO- at least 2000A thick, 3) Nitride (not low stress, NEWLSN program), 4) Poly- at least 2000A thick and 5) Photoresist on Single Crystal Silicon- litho quals wafers are good for this, 3612 resist at either 1um or 1.6um is good.  Do not use the thicker SPR220 resist- it will burn.
  2. Season the chamber for 10 minutes using Program 3.  Be sure to check the program parameters before starting.
  3. Measure the Pre-Etch thicknesses for the various thin films on all the wafers using one of the Nanospecs.  Be sure to use reference wafer before testing to calibrate the tool.  Take readings for the Center, Top, Flat, Right and Left positions of the wafer.  Readings should be taken about 15mm from the edge.  See Fig. 2.  No measurement is taken on the single crystal silicon wafer with PR.
  4. Place one wafer in the second position from the top for each of the six trays, flats down.   See Fig. 1.
  5. Etch for 2 minutes using the standard oxide etch program, #3.  Monitor gas flows, RF power and bias and record on Monitor Log Form.
  6. Measure the Post-Etch thickness of each wafer using the same Nanospec.  Be sure to use reference wafer before testing to calibrate the tool.  Take readings for the Center, Top, Flat, Right and Left positions of the wafer.  Readings should be taken in roughly the same place as the first measurements.  See Fig. 2.  Use alphastep, P2 or zygo to read the single crystal Si etch depth after PR is removed from the wafer.
  7. Record results on the Monitor Log.  Record results in data file to get wafer-to-wafer and within-a-wafer
    1. Subtract the Post-Etch average reading from the Pre-Etch average reading for each for each wafer to get the total amount of material etched.
    2. To get the etch rate per minute divide the average total material etched measurements by 2. 
    3. To get the selectivity for oxide vs photoresist divide the oxide etch rate by the photoresist etch rate.  To get the selectivity for nitride vs photoresist divide the nitride etch rate by the photoresist etch rate
  8. Record etch rates and selectivities on Badger as a comment and the labmembers wiki in table form.  Data may also be recorded in an appropriate spreadsheet.

 

Fig. 1. Place wafers in the second position from the top on each tray, flats down.

 

Fig. 2. Nanospec readings should be made in the above positions and recorded.

 

Recent Qualification Results

 

To view recent qualification results click here.

 

Processing Information

 

Standard Recipes and Etch Rates

 

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