Resonetics RapidX250-L
Excimer Laser Micromachining SOP

0. Introduction

RapidX250-L Series

The Resonetics RapidX250-L Series is an excimer laser-based laser micromachining system designed to fabricate micro-machined components as small as 1 micron feature size.  The system can laser machine polymers, glass, sapphire, ruby, silicon, ceramics and metals among others.

The RapidX 250 –L incorporates an excimer laser with 80 Watts of average power at 248nm laser wavelength and 50 Watts at 193nm.The laser repetition rates range from 0 to 200 Hz.

The RapidX250-L Series is available in two (2) laser wavelengths, 248nm and 193nm. The user has the option to select both laser wavelengths with quick change between wavelengths, offering the greatest flexibility in terms of material choice and applications.  

The RapidX 250 series was designed for 2-D and 3-D laser micromachining. A typical system is comprised of 200mm x 200mm XY stages with optional Z axis, rotary and goniometer (45 degree tilt), permitting the most complex geometries to be machined, The system includes a user-friendly CAD conversion software package to allow the CAD drawing to be converted directly to machine code. The system has a camera vision system for part alignment and process viewing.

The system offers several options such as motorized rectangular variable aperture and a motorized aperture wheel.

How to start the excimer laser

1. Start a new entry in the log book.

Begin each entry with the date and time. Check the gauges within the vented gas cabinet, and record the pressures on the delivery and supply sides of each pressure regulator.

The laser vessel normally needs to be refilled after 1-2 weeks and you can find out when it was last filled on the log book.

b. Turn ON water chiller (5 - 20 C)

The thermostat is preset to 5 - 20 C and the chiller should stabilize at this temperature a few minutes after being turned on.

Water chiller. Temperature should be between 5 to 20 C.

If the water level is too low, a high-pitched alarm will sound.  In this case, remove the cap from the tank and fill with spring, tap, or distilled water to just below the threads for the cap.  DO NOT USE DEIONIZED WATER. Find water bottles next to water chiller.

Water reservoir.

c. Turn ON laser

Open the front door on the laser cabinet, which is at about ankle level on the front, bottom right wall of the Laser Table and turn the red interlock swtich clockwise to the “ON” position. Then turn the keyswitch to the “ON” position.

Note that there is a 5 minute warm up for the controller after turning the key “ON”. You will also get the message “Check Water. Press <EXIT>”.  And you should press <EXIT>.

2. Warmup/Test-fire the laser to determine beam energy

On the laser control pad:

  1. Set the pulse repetition rate (PPS) to 30 Hz,

  2. excitation voltage to 30 kV,

  3. close the beam stop box on top of the b/w monitor,

  4. set to TRIGGER MODE to INTERN,

  5. press the RUN button on the controller (which will then display standby), hit run again to run.  

  6. The pulse energy should be >300 mJ. Let the laser run for 4-5 minutes and then hit stop.

  7. Record parameters and values displayed on laser control pad in the log book (e.g. “300 mJ @ 30 kV, 10 Hz”).

NOTE: what should I look for here that could be wrong. Like beam energy too low, or pressure too high etc...

[It would be nice to have a photo here with the right settings]

3. Gas fill procedure [every 1-2 weeks or when pulse power drops below 300 mJ @ 30 kV, 10 Hz]

The table below or look in the manual (on Laser Table) for prescribed laser energy (dependant on wavelength).  Moreover, when output energy is below 200mJ, gas fill is required. Note that the maximum KrF laser energy is 400mJ.  Do not operate the laser at a voltage outside of the values given in this table.

Laser Type

Min kV

Max kV

Wavelength

KrF

26

35

248nm

ArF

28

37

193nm

(Before starting any of this, turn laser on and let the chamber heat up)

a. Turn on vacuum pump

To turn ON vacuum pump, open quarter valve and run for 5 minutes to create a vacuum behind the halogen scrubber. The vacuum pump door is about ankle level in the on the right wall of the Laser Table.

Turning on the vacuum pump.

Quarter valve is the black valve on the right side of the image.

The quarter valve is open when the handle is in line with the tubing, and closed when the handle is at a right angle.

(Keep the pump and valve on during the filling process)

b. Open Neon, Krypton, and Fluorine gas lines.

Please ensure you follow the tank lines to understand where each tank is and which valves/ knobs correspond to each gas type.

1. First open each of the tank knobs, please follow order (Ne, Kr, F).

[We need a good image here with tank knobs marked and numbers for order]

2. Then open the process knobs for, please follow order  (Ne, Kr). The F process valve should be open already. Do NOT open the He gas tank knob or process knob.

3. Ensure the regulated pressures are 80psi or greater.

[Another image here with things crossed that are not supposed to be turned on]

c. Disable sensor channel #6

Disable sensor channel #6 on gas cabinet controller (this is the touch screen display above the gas cabinet).

PLEASE FOLLOW WITH DILIGENCE AND DO NOT PRESS OTHER BUTTONS, IN PARTICULAR THE [ALARM] BUTTON ON THE LAST SCREEN.

Interface to disable sensor channel #6

  1. Press and hold the clock display; the time should should disappear after 3 seconds, leaving only “--:--”. Release.  When the clock appears again, press and hold again to activate the controller’s menu.

  2. The screen will change to a menu with several options. Press Set channels >> Next >> Chan 6 >> Active.  [Active] will then change to [Disabled]

  3. Done >> End >> Exit

At random times approximately twice a day, the HF/ F2 sensors will self-test.  The two numbers displayed on the sensor controller indicate the sensed atmospheric level of HF in parts per million (PPM).  When a self-test occurs, the controller will beep briefly, and the display will indicate ~2.0ppm and decrease back to 0 in about 1 minute.

d. Open fluorine solenoid

Find the fluorine solenoid box on the Laser Table next to the gas cabinet. Turn ON the switch for the fluorine solenoid.

Fluorine solenoid switch.

e. Perform an auto-fill of the laser vessel

Ensure that all gas cylinder valves are open and that all gas tanks are pressurized to at least 250 PSI. The default autofill recipe is KrF for operation at 248 nm.

[photo here would be helpful indicating what needs to be checked]

On the laser control pad on the Laser Table (above the keyboard), press the Autofill/Ne button > ENTER. This will start the refill process. (if check water is shown on Laserpad, press enter to acknowledge) (if interlock is displayed: ensure Resonetics door is closed, and check door on back of Resonetics to ensure closed)

The laser control pad will display the pressure. The laser vessel is typically pressurized to 5000 mbar.

The autofill procedure will pump the vessel down to 80 mbar, add 100 mbar of 0.09% F and 100 mbar of 1.80% Kr, then fill the balance with Ne.  The final vessel pressure should be approx. 5000 mbar.

Read-out during the autofill procedure.

When autofill is complete, press exit on the laser control pad.

** If the fill fails.

f. Shut off the gas supply (in this order)

[picture here]

  1. Shut off the F solenoid.

  2. Then turn off the process valves for Kr and Ne. (Don’t turn off the F process valve)

  3. Then turn off the gas tank valves (F, Kr, Ne).

  4. Turn off the quarter valve and then turn off the vacuum pump.

h. Re-enable sensor channel #6 on gas cabinet controller. PLEASE FOLLOW WITH DILIGENCE AND DO NOT PRESS OTHER BUTTONS.

[pictures and description of procedure here]

1.Press and hold the clock display; the time should should disappear after 3 seconds, leaving only “--:--”. Release.  When the clock appears again, press and hold again to activate the controller’s menu.

2. The screen will change to a menu with several options. Press Set Channels >> Next >> Chan 6 >> Disabled. [Disabled] will then change to [Active]

3. Press Done >> End >> Exit

i. fill out a gas fill report form found in binder on shelving in front of laser. Note to fill gas tank pressures AFTER fill procedure. (Doc #064, Rev B)

4. Make an entry in the log book

Please take this seriously -- it is important to keep a record of the laser’s operation and performance to determine when maintenance is required.

[details of filling out the gas fill report]

[picture??]

Note that laser access and privileges are contingent on following protocol. Lasers alone can cause bodily harm, and gases used can cause both harm and large amounts of damage. If you think it doesn’t matter and cut corners, you are endangering the next user, the facility and success of not only your work but your colleagues’.

5. Using the Resonetics RapidX Laser micromachining system

1. Switch on the B/W monitor.

Monitor switch button on the right

2. Switch on digital cross-hair generator on top of monitor.

Cross-hair generator

3. Make sure the proper beam mask is inserted. For focusing, use the mask shown in the image:

Calibration mask (left) and beam path with mask location indicated (right)

4. Open the beam stop.

Green light on means beam stop open.

5. Switch the laser trigger to EXTERN to allow the Resonetics graphical interface to control laser firing.

6. Change step size to 0.1 mm/s

7. Change feed rate to 3 mm/s

8. Change T for pulse rate and frequency

9. Insert mask in beam path if required.

Zero axes (x, y, z) at origin

Press L to fire laser

Open the Resonetics Laser Box and switch on vacuum and exhaust controllers on left wall. Switch on light on back (bottom) wall).

Place a piece of polyimide for focusing (glass can also be used).

Adjust lights to illuminate sample based on b/w monitor image.

Focusing the beam and camera:

Put in mask the is shown in the picture below.

(i) Shoot a shot onto the polyimide/ glass. Adjust camera to get a focused image and center cross-hairs.

(ii) Shoot a shot onto the polyimide/ glass. Adjust  Z axis to focus mask image on polyimide/ glass.

(+/- on keyboard to adjust Z; < > to move on x-axis; up/down arrows to move on y-axis)

(iii) Repeat steps (i) and (ii) above till you get a focused clear image as shown in the figure above.

(iv) Check image using a microscope and focus more if required.

[image of adjustment knobs]

[auto focusing script and procedure to find Z=0 position]

[Hello World: cut a square out of shim stock]

[cad.py -> WinRPC workflow]

Focus Process

1. Start with small mask

2. Use patterned mask

3. After focused, use Z stage to match cross hair with laser point

Replacing Water

Before you start switch off the laser!!

1. Turn off water cooler

2. Get new Polar Spring water bottles (DO NOT USE TAP WATER OR DISTILLED WATER)

3. Take out black cap from water cap

4. Unscrew water cap from water reservoir

5. Unscrew return hose clamp

6. Remove return hose and put it in an empty polar spring bottle

7. Put the black cap in the return hose fitting (nipple?)

8. Make sure valve on the back is open

9. Put full bottle into reservoir

10. Turn the cooler on

11. When the water level is at the end of the bottle (but not over yet), switch cooler off

12. Remove (now empty) bottle

13. Put water reservoir cap back on

14. Put hose back on return fitting and screw it in place with clamp

15. Turn cooler back on

 

6. Gas supply and maintenance

Neon

Ordering

From: John Jordan <John.Jordan@airgas.com>

To: Rehmi Post <rehmi@cba.mit.edu>

Date: Thu, Jan 6, 2011 at 09:33

Hello Rehmi,

 The equivalent Airgas part number on ECAT is

NE R2006000LT. Cost is $1680.00.

Thank you

John

From: Manu Prakash

To: Rehmi Post

Date: December 20, 2010

This is the Neon order - Spectra gases was bought by Airgas.

Vendor: Spectra Gases

Part number : EXPGNE 1-2      (Excimer Pure Gas Neon)

Neon Research Grade 99.999% pure

Cylinder Size # 2

2000 psi, 6000 ltr

Price $1363

Changing Krypton (and Neon) gas bottles

Download the original attachment

Neon, Helium, Krypton, Argon Gas Bottle Change Procedure

For Lumonics PM800 Series Laser Systems 

 

  1. Purpose

  1. To prevent impurities from entering the laser vessel, it is important that gas bottles be changed before the pressure in the bottle becomes too low.  Otherwise, severe contamination, shortened vessel lifetime, and poor performance may result.

  2. The following table lists minimum recommended pressure to change a gas bottle.

GAS

Pressure

Neon

250 psig

Krypton or Argon

250 psig

Helium

250 psig

 

  1. Do not attempt a gas fill if bottle pressure is below value in above table.

  1. Scope

  1. The following procedure is used to change Neon, Krypton, Argon or Helium gas bottles on Lumonics lasers.

    1. Turn chiller and laser on (keyswitch and interlock)... wait 5 min

    2. Turn vacuum pump on

    3. Purge lines

      1. close all tank valves (may or may not close process valves). Keep helium valve open. Leave Neon process valve open.

      2. Valve Control → VAC → Ne (for Neon)

      3. Close Ne tank valve, Open purge valve for Helium and Neon.

  1. Safety

3.1 Safety Glasses

3.2 Gas Bottle transfer cart

3.3 Gas Bottle safety cap

3.4 Only individuals certified by Resonetics to perform the cylinder gas exchange procedure may perform this task.

NOTE:  Never transport bottles without the use of the transfer cart.  All bottles must have safety cap firmly installed during transport.   

  1. Requirements

4.1 Laser Log Book

4.2 Current Resonetics Cylinder Exchange Training Certification 

  1. Equipment

5.1 Wrench

5.2 Snoop or helium leak detector 

  1. Gas Pressure Level

  1. 6.1 Neon, Helium, Krypton and Argon bottles must be changed at 250 psi. 

  1. Procedure

NOTE: Do Not Exchange Gas Bottles During A Process Or While The Laser Is Running!

7.1 Turn on vacuum pump.

7.2 Open valve between pump and laser.

7.4 Open all gas bottles and regulators.

7.5 Set regulators to 80 PSI.and close the gas bottle and regulator that is not being

          replaced.

7.6 Fluorine Gas Line Evacuation

7.6.1        Close Fluorine bottle valve.

7.6.2        Evacuate Fluorine Line using control paddle on laser

7.6.2.1  Press Valve Control button.

7.6.2.2  Press VAC button.

7.6.2.3  Press and hold F, CL.  Monitor the fluorine                  regulator and hold F, CL button until regulator is under vacuum.

NOTE:  While evacuating bottles monitor the regulators to ensure they are evacuating.  If the bottle is not near the laser then monitor the gauge on the vacuum pump. However a visual verification that the bottle is under vacuum is still necessary. The line is evacuated when the vacuum gauge no longer moves when the F, CL button is cycled.    

7.7 Fill Fluorine Line with Helium using control paddle on laser

7.7.1        Press He button.

7.7.2        Press and hold F, CL button and toggle 4 times.  

7.8   Repeat step 7.6 and 7.7 a second time.

7.9   Repeat Step 7.6 and 7.7 a third time.

7.10 Close the valve on the fluorine regulator. 

      NOTE:  The Fluorine line is now filled with Helium 

7.11 Change Neon Bottle 

NOTE:  Do not change bottle without evacuating and filling fluorine gas line with Helium.  See section 7.6 to 7.10. 

            7.11.1 Close bottle valve on Neon bottle

7.11.2 Evacuate Line using laser control paddle.

7.11.2.1  Press Valve Control button

Press VAC button.

Press Ne button

Monitor Ne regulator and watch until regulator needle

                            moves to 0      

Press VAC button.

Press He button  to fill Neon line with helium

Press He button

Press Ne button

Repeat section 7.11.2.2 to 7.11.2.8 ** at least 3 times

Close the valve at the exit of the regulator on the Neon bottle

Remove the regulator from the bottle.

Replace Bottle

Install Regulator.  Do NOT open bottle valve.

Open valve at exit of regulator.

Evacuate air from line and fill with helium by repeating step 7.11.2.

Leave regulator filled with Helium and note the exact pressure. DO NOT close regulator valve and monitor the pressure for five minutes. If the pressure does not drop then the gas line has no leaks.

Remove Helium from line by following steps 7.11.2.1 to 7.11.2.4 ONLY.

Set regulator pressure to 0 by turning regulator pressure valve counter-clockwise.

Open bottle valve and set regulator to 80PSI

Proceed to sections 7.14

 

7.12 Change Krypton or Argon Bottle 

NOTE:  Do not change bottle without evacuating and filling fluorine gas line with Helium.  See section 7.6 to 7.10. 

7.12.1 Close bottle valve on bottle being changed

7.12.2 Evacuate line using laser control paddle.

7.12.2.1         Press Valve Control Button

7.12.2.2 Press VAC button.

7.12.2.3 Press and hold Rare button

7.12.2.4 Monitor Krypton or Argon regulator and watch until regulator needle moves to 0

7.12.2.5 Press VAC button.

7.12.2.6 Press He Button

7.12.2.7 Press and hold rare button to fill line with helium

7.12.2.8 Press He Button

Repeat section 7.12.2

Close the valve at the exit of the Krypton or Argon Bottle

Remove the regulator from the bottle.

Replace Bottle

Install Regulator.  Do NOT open bottle valve.

Open valve at exit of regulator.

Evacuate air from line and fill with helium by repeating step 7.12.2.

Leave regulator filled with Helium and note the exact pressure. DO NOT close regulator valve and monitor the pressure for five minutes. If the pressure does not drop then the gas line has no leaks.

Evacuate helium from line by following steps 7.12.2.2 to 7.12.2.4. ONLY.

Set regulator pressure to 0 by turning regulator pressure valve counter clockwise.

Open bottle valve and set regulator to correct pressure.

Proceed to sections 7.14

 

Change Helium Bottle

 

NOTE:  Do not change bottle without evacuating and filling fluorine gas line with Helium.  See section 7.6 to 7.10. 

7.13.1 Evacuate Helium Line using laser control paddle.

Press Valve Control button

Press VAC button.

Press He button

Press He button again

 

7.13.3 Close the bottle valve and the valve at the exit of the regulator on the Helium bottle.

7.13.4 Remove the regulator from the bottle.

7.13.5 Replace bottle

7.13.6 Install regulator. Do NOT open bottle valve.

7.13.7 Open valve at exit of regulator.

7.13.8 Evacuate air from the line and fill line by repeating step 7.13.1.2 to

      7.13.1.4.

7.13.9 Set regulator pressure to 0 by turning regulator pressure valve counter-clockwise.

7.13.10 Open bottle valve and set regulator to correct pressure.

7.13.11 Repeat step 7.13.1.2 to 7.13.1.4.

7.13.12 Proceed to section 7.14

7.14  Leak check regulator

7.14.1   Close bottle valve

7.14.2   Monitor regulator pressure for 5 minutes

7.14.3   If pressure does not drop then regulator is leak tight.

7.14.4   If test fails notify service department

  7.15 Purge Gas line 

7.15.1   Open bottle valve and valve at exit of regulator

7.15.2   Press Valve Control Button

7.15.3   If Neon bottle was changed, press Ne button and leave open for 2 seconds. Press Ne to close valve.

7.15.4   If Helium bottle was changed, press He and leave open for 2 seconds. Press He to close valve.

7.15.5   If Krypton or Argon bottle was changed, press and HOLD Rare button until it toggles four times.

7.15.6   Press Exit. 

7.16   Open Fluorine line 

7.16.1 Open valve at exit of fluorine regulator

7.16.2 Press Valve Control button

7.16.3 Press VAC

7.16.4 Press and HOLD F, Cl button until the regulator gauge reads 0

7.16.5 Press Exit

7.16.6 Set regulator pressure to 0 by turning regulator pressure valve counter-clockwise

7.16.7 Open fluorine bottle valve

7.16.8 Set fluorine regulator to correct pressure

7.16.9 Press Valve Control button

7.16.10 Press VAC button

7.16.11 Press and HOLD F, CL button until it toggles four times.

7.16.12 Press Exit. 

     7.17  Bottle change is complete.

     7.18  Turn off vacuum pump

7.18.1   Close valve between pump and laser

7.18.1   Turn off pump 

Change History 

Revision

Date

COR#

Description of Change

A

6-19-07      

06-19-07-M2

Initial Release

Links to other documentation

Excimer Laser Micromachining

Process Controller Command Reference

Things that can go wrong and what to do

Overheating:

Start-up Interlock:

You forget to turn the alarm off:

You do not follow the right gas filling sequence: