I wonder: could one use an optical burner to create a mask? - Page 1
Forum section: electronics / general

author: tyblu
author_rank: Frequent Contributor
timestamp: February 18, 2011, 06:28:03 pm
content: I wonder if I could use one of the high-speed (ie: high power, 1W'ish) BluRay burners to scribe a high-density pattern into a substrate as one of the first steps in creating a microelectronic mask? Currently, fabs use electron beams (and a couple other fancy high-energy beams) and a high resolution XY table stepper in order to create the initial glass mask. [One of the initial steps in IC fabrication; used to create negative masks for exposure.] Though there's no way a 405nm beam could replace a high power electron beam, surely it can do something? The Great WikiP states that the spot size is currently 580nm, though I imagine the burners use larger tolerances.Although burners now follow a set spiral along a standardized pitch, surely the drive is capable of arbitrary positioning to within better tolerances than the pitch? For a CD, this is 1.6um -- not sure if it's different for BluRay, but this is damn small.So, process engineers, what can I do with a 1W 405nm laser with 580nm spot size and sub-micron positioning abilities? What could it 'burn' that could be used to create high-resolution masks?

author: Simon
author_rank: Unknown
timestamp: February 18, 2011, 08:29:12 pm
content: well you alreasy have one axis of motion in the mechanism although your idea cannot make use of the rotation from the main motor, as a blue ray has more data than a CD I guess the tracks are thinner and positioning more critical as I'd assume it the case with DVD's although CD's do have extra tracks for error correction

author: baljemmett
author_rank: Unknown
timestamp: February 18, 2011, 09:46:03 pm
content: Quote from: Simon on February 18, 2011, 08:29:12 pmPretty sure they don't, the track on a CD is a single long spiral; error correction is performed using in-band data.With regards the positioning ability of the drives, I don't think it's entirely arbitrary at the finest level. When reading, drives position the laser using a combination of mechanical drive for the coarse positioning and then feedback on the quality of the reflected beam to tilt the optics to follow the track precisely. Recordable discs, at least in the case of CDs, have a spiral track pressed into them which the laser follows in the same way -- so without that feedback loop, the coarse tracking motor is going to be the only positioning system available. I fear it'll be hopelessly inaccurate compared to the tracking ability of the system as a whole!

author: Unknown
author_rank: Unknown
timestamp: February 18, 2011, 10:30:44 pm
content: Quote from: baljemmett on February 18, 2011, 09:46:03 pmThey also use positioning data encoded in the track to find the exact track. This is why seeking on audio CDs (which lack this information, they have a minimal amount of error correction and overhead to maximize the amount of audio that will fit) is much slower and/or less accurate than seeking on data CDs.

author: PeterG
author_rank: Frequent Contributor
timestamp: February 18, 2011, 11:42:11 pm
content: There are several projects that make use of the laser found on either 16x DVD burners or the fast BlueRay burner. The projects i have been interested in are based on a pair of steppers salvaged from flatbed scanners set up on an XY configuration. The level or detail you can achieve with these systems is only limited by your budget.The people over athttp://laserpointerforums.comshould be able to help you out further.Regards

author: tyblu
author_rank: Frequent Contributor
timestamp: February 19, 2011, 03:55:29 am
content: Found this info here:http://wiki.answers.com/Q/What_is_the_track_pitch_or_groove_spacing_on_a_CD_DVD_or_Blu-rayType -------- Capacity ---------------Track pitch ----------Wavelength of laser light------Numerical ApertureCD -------------- 0.7 Gb ------------------ 1.6 ?0.1 ?m ------------- 780 nm (0.780 ?m) ------------------- 0.45DVD ------------ 4.7 GB ------------------- 0.74 ?m ------------------ 650 nm (0.650 ?m) ------------------- 0.60Blu-ray Disc --- 25 GB ------------------- 0.32 ?m -------------------405 nm (0.405 ?m) ------------------- 0.85If "course control" is on the order of a micron, that is more than acceptable. Now, onto the chemical process...

author: FreeThinker
author_rank: Frequent Contributor
timestamp: February 19, 2011, 11:02:51 am
content: As a complete novice to IC manufacture I could be (and more than likely am) completely wrong but I thought that the mask was much larger and was optically reduced to expose the silicon? Are you talking etching the silicon direct?

author: tyblu
author_rank: Frequent Contributor
timestamp: February 19, 2011, 06:44:35 pm
content: Indeed, that is called 'stepping', and optics are used to change the size of the image, but there are several methods used. A common method is to first create a positive glass mask, which is then used to make negative exposure masks, which is in turn used to expose photoresist...I wonder if there is a copper-etchant photoresist available for IR (405nm), allowing one to go directly to FR-4 and copper? The "LightScribe" capabilities of new BluRay burners make things interesting...