HD DVD: Manufacturing Was Developed.This Recorder Is Equipped with a 257Nm Gas Laser (Frequency Doubled Ar+ Laser)

white d Six years ago, the LDM 3692 DUV recorder HD DVD: Manufacturing was developed.This recorder is equipped with a 257nm gas laser (frequency doubled Ar+ laser). All options with regards to future formats were still open at that time.The recorder features two recording spots, with a wobble The New Format option on both. This recorder is an adequate R&D tool to record HD DVD. BY DR. DICK VERHAART, from 740nm to 400nm. To read these smaller For HD DVD stamper manufacturing, a Singulus Mastering information structures, it is necessary to use recorder with a 266nm solid state laser was PETER KNIPS, blue diode lasers with a wavelength of 405nm developed. This system contains a stable and Singulus EMould instead of the 650nm red lasers used for CD easy to operate solid state laser, with a much DIETER WAGNER, and DVD. longer lifetime than the gas laser. As all pro- Singulus Technologies AG An advanced copy protection system will posed next-generation formats require only The third generation of optical disc formats is give better protection than what was avail- one spot, the system has a single recording set to arrive on the market by the end of this able for CD and DVD with mandatory serializ- spot. Spot deflection, required to create the year.As with Blu-ray Disc, the HD DVD format ing of each single HD DVD. The serialization groove wobble in the recordable and was developed to tremendously increase the will take place on the aluminum covered layer rewritable formats, is available as an option. capacity of optical discs. While structurally 1 discs half of the DL by usage of a BCA (Burst The crucial factor in mastering is the size similar to its standard-definition predecessor, Cutting Area) Marker and likely will be an of the mastering spot in relation to the pit to HD DVD does involve several new production integral part of the replication machinery. An be created. For HD DVD with a DUV technologies and processes. offline solution might be also possible. recorder, this is slightly less favorable than HD DVD AND DVD MASTERING for DVD with a standard diode laser To maintain compatibility, the disc structure of The higher capacity of HD DVD with smaller (405nm) recorder (see “pit/spot” entry in HD DVD is quite similar to a DVD, which sim- track pitch and pit sizes requires an improve- Fig. 3). The process is sufficiently well-con- plifies its manufacturing process. Both for- ment in the mastering technology. trolled to overcome this disadvantage. mats are approved by the DVD Forum and The format is mastered with a deep UV For DVD, data-to-clock jitter is the key qual- consist of two 0.6mm-thick polycarbonate (DUV) recorder. In the lower part of Fig. 2, we ity parameter. HD DVD performance is speci- disc halves, each with a diameter of 120mm, compare characteristics of the HD DVD fied in terms of the PRML decoding scheme; which are metallized and bonded together. recorder to the characteristics of a standard key parameters are SbER and PSNR. A dual-layer (DL) format is easily achieved, DVD recorder. Fig. 3 summaries the specs and typical thus increasing capacity from 15GB on a single layer disc to 30GB (Fig. 1). This increase can only be reached by reducing the pit length from 400nm to 204nm and the track pitch

Singulus has already prepared its Master- ing, EMould S2000/3 and Spaceline II HD products to meet HD DVD demands. 48 ❙ www.medialinenews.com May 2005 whitepaper

laser laser beam beam laser laser beam beam Fig. 1: Disc structure: DVD and HD DVD

Fig. 2: Comparison of recorder characteristics

Fig. 3: Stamper specifications and typical results

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Fig. 4: Test disc results

Fig. 5: 3-D AFM image of HD DVD and DVD substrates

results for HD DVD replicated from a master using the 266nm DUV recorder. Results from a test disc, with bands recorded at different intensities, give an impression of the process window. MOLDING Maximum output at low energy costs along with outstanding mechanical, optical and electrical disc properties summarize today’s demands on injection molding technology. The balancing act between the dramatic reduction in cycle times and best replication rates, especially for the recordable formats and third-generation optical discs, requires increased process reliability and precision. The substantial increase of capacity to Fig. 7: Comparison of DVD and HD DVD specifications

50 ❙ www.medialinenews.com May 2005 whitepaper

Fig. 6: Dr. Schenk measurement printout of an HD DVD substrate

15GB per side on an HD DVD disc in compari- erties are achieved by lower mold tempera- disc properties of an HD DVD substrate mold- son to 4.7GB of a DVD-5 is generated by ture, slower clamp movement and longer cool- ed in 3.0 seconds. Tangential deviation less smaller pits and less track pitch. The replica- ing time, all of which directly conflict with the than 0.05 degrees and substrate thickness tion of pits with a minimum length (2T) of only demands for best replication and shortest variation of less than ±2µm on track is 200nm has been the challenge in all-electric cycle times. achieved by the molding system (injection injection molding, as the limits for some As such, the injection molding process for molding machine and mold) and balanced mechanical disc properties are even tighter HD DVD requires various modifications in com- process control. than for DVD substrates. parison to DVD. The primary changes are: THE MANUFACTURING LINE Replication of micro structures like those on • The mold is modified to fulfill the tighter HD DVD requires other improvements besides an HD DVD stamper requires high melt and limits regarding eccentricity and to achieve mastering and molding. For the replication mold temperatures to ensure that the viscosi- minimum thickness variation equipment, the major demands are increased ty of the polycarbonate is low enough to form • Water flow and temperature regulation uniformity of the metallized layers, tighter the pits.As an injection compression process is (±0.1 K) of the mold heaters are optimized to bonding characteristics, as well as use of spe- used as with DVD, high acceleration and clamp ensure a stable dishing cialized quality inspection systems. speed are required for fast distribution of the • The plasticizing process is adapted to As the BCA-Marker process requires a met- PC and to guarantee the best replication rates meet the requirements in melt homogeneity allized disc half, the uniformity of the alu- (approx. 96 percent) to the outer diameter of and minimum shot weight variation for bond- minum layer also becomes important. If too the disc. ing reproducibility much material is sputtered, the BCA-marker For focus and tracking reasons the flatness • A high speed clamping profile (up to 6 will not be able to burn the serial code onto of the HD disc becomes substantially more steps) has been implemented for high replica- the disc, while too little material will cause important than for DVD. Uniform thickness tion rates even with relatively low mold tem- problems on the codes contrast due to the and minimum tangential deviation are key for peratures reduction of the total reflectivity. high quality HD DVD. These optimal disc prop- In Fig. 6, the reader can see the mechanical As opposed to single-layer disc production,

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Fig. 8: Finished HD DVD DL

where aluminum is used, the layer 0 half of a DL disc is metallized with silver alloy as the only possible material. This choice is FOR HD DVD REPLICATION EQUIPMENT, THE MAJOR DEMANDS based on the high reflectivity provided even on thin metallized layers, combined ARE INCREASED UNIFORMITY OF THE METALLIZED LAYERS, with the small absorption rate for 405nm laser units. TIGHTER BONDING CHARACTERISTICS, AS WELL AS USE OF Besides additional requirements regard- SPECIALIZED QUALITY INSPECTION SYSTEMS. ing the metallization of the substrates, the thickness and tolerance ranges of the spac- er layer in between both discs halves have been minimized to 20µm with tolerances of ±5µm on disc and ±2µm on track (see Fig. needs to be kept at a consistent level to The last production step is covered by 7). These reductions can only be achieved avoid start-up problems. This can only be the quality inspection system. Today’s by replication systems with highly accurate guaranteed by an accurate tempering standard DVD scanners are usually not dispensing of bonding material, bonding device in closest possible proximity to the able to verify the quality issues of HD process and spin-off. Also important to dosing device. DVD, but major scanner manufacturers increased productivity and reduced produc- After the bonding process, it must be have already developed solutions for the tion costs will be the ability to switch easi- mentioned that the limits of Radial Runout third generation of optical discs so that a ly between DVD and HD DVD, thus reducing between both disc halves were reduced by certain number of DVD scanners might be production downtimes. As it is predicted the DVD Forum from 100µm for DVD to less upgraded or exchanged to serve the spec- that no target exchange will be required then 70µm for HD DVD. ifications for HD DVD production. during a format change, the bonding mate- Certainly the concentric alignment of OUTLOOK rial should be adopted to the new format both disc halves before the resin curing Singulus Technologies AG has already pre- within the timeframe of a simple stamper occurs has an important role during the pared its Mastering, EMould S2000/3 and exchange. Therefore it will be necessary to manufacturing process, but it should be Spaceline II HD products to meet the HD DVD have bonding materials available that can taken into account that greater accuracy demand (see Fig. 8). Even the integration of easily be used for manufacturing DVD as during stamper fabrication and molding- a BCA-coding system already has been well as HD DVD similarly providing a low e.g., stamper punch, stamper holder, mold designed. Cycle time for HD DVD soon will be absorption for the 405nm laser wave- alignment and the molding process-needs close to the current cycle time for DVD. length. Also, the bonding agent’s viscosity to be achieved. www.singulus.com

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