Holographic Grating Lithography System （Laser） SOP

<p>APPLIED OPTOELECTRONICS, INC.DOCUMENT COVER SHEETDocument Number04-00-0001Document DescriptionHolographic Grating Lithography System (Laser) SOPDocument FormatElectronicDate Created11/15/2002Created ByK. Alex AnselmRev.#Revised ByDateRevision Historyx001B. Guo11/15/2002Initial release.x002H.L. Zhang07/31/2006Revision 002x003H.L. Zhang09/24/2007Added Additional Safety guidelines001B. Shelton10/26/2010Removed process summary and added more detailed procedure. &nbsp;Converted from WI-04-00-0015002H.L. Zhang12/20/2010Added details about argon laser maintenance.Holographic Grating Lithography System (Laser) SOP1) Read and understand all of the laser safety guidelines in Appendix I.a. Turn on the Laser and adjust using the details specified in Appendix II.2) Follow the procedure to prepare the wafer for the exposure process.3) Expose in the holographic system, using the procedure described in Appendix III.4) Argon laser maintenance:Frequencya. Laser optical output power monitoring: Weeklyi. See procedure in Appendix IVb. Laser optical intensity profile measurement: Tube install or after alignment change, and monthly thereafter (after conditioning below).i. Follow procedure in Appendix V.c. Laser tube conditioning: Tube install, monthly thereafter. i. Follow procedure in Appendix VI.Appendix ILaser Safety GuidelinesThe laser used in AOIs grating lithography system is a Spectra Physics BeamLok 2060 Argon gas laser. The maxim rated optical power with the 2060-5S plasma-tube and 363.8nm optics used is 170mW. This laser is a Class IIIB laser. The nominal operation power of the laser during normal operation is 70mW at a UV wavelength of 363.8nm. The radiation of this laser can be dangerous to eyes and skins if exposed. Several safety features and procedures have been built in the grating lithography system to minimize the danger of accidental laser radiation. The laser and the grating holographic lithography optics are enclosed in an enclosure on the optical table. No laser beam is directed outside of the optical table. A controlled-access area was established surrounding the optical table using black curtains. The laser beam is normally blocked by the remote digital shutter except at the time of grating exposure. The duration of the exposure is very short, in the most cases only between 1 to 2.5 mins per wafer. The power of the laser beam before the pinhole is 70mW, but after the pinhole the beam diverges and is later collimated into a 6 inch parallel beam, so the optical power in front of the sample stage is only 0.2mW. This is the power level the operator could accidentally get exposed during normal operation (which is equivalent to a Class I laser). Higher power exposure is possible during service and alignment. The laser is normally serviced by service engineers from the manufacturer once every two years. Alignment of the optics is only performed when its necessary. It is usually only required when the laser tube is replaced. The following guidelines should be followed by all personnel working with this system. 1. Only qualified and authorized personnel can operate the grating lithography laser system. 2. All personnel work in the grating lithography process need to be familiar with laser safety practices. Observe all safety precautions in the manufacturers Operator&#39;s manuals and this guideline. A copy of the manufacturer safety manual is placed next to the system.3. The remote digital shutter should be in the “OFF” position when it is in standby mode. It is only activated during wafer exposure by the same person who places the sample on the stage. 4. Never look directly into the laser beam or at scattered laser light from any reflective surface.5. Avoid direct exposure to the laser light. The intensity of the beam can cause skin burns. Wear protective gloves and clothes at all times to protect the skin (the laser is located inside a class 100 cleanroom, gloves and coverall garment is a requirement for entering this room).6. No routine service and alignment is needed for the laser and the holographic optics. The engineer who takes charge of this system will determine when service and/or alignment are necessary. 7. Laser safety glasses are required during laser tube service and alignment of the optics as a precaution against accidental exposure to the output beam or its reflection. They are located on the wall near the sample stage and on the wall near the laser remote control module.Appendix IIDaily Laser OperationBefore turning laser on, check to make sure that the power is ON on the laser power supply, (you can see a green LED on the front panel). The remote control and Z-Lok all have the digital display on the panels.Turn On Procedure:1. Turn on the cooling water, first OPEN the inlet and return water valves (Mounted on the wall), the pressure gau</p>