Site:3M Data Storage Diskette and
Optical Technology Division
3M Center, Building 236-1B-99
St. Paul, MN 55144-1000

Date Visited: October 24, 1994

Report Author: S. Esener

ATTENDEES

JTEC:

M. DeHaemer
S. Esener
R. Hickernell

HOST:

Dr. Steven Webster
Technical Director

BACKGROUND AND ORGANIZATION

3M is a global leader in consumer and professional video markets and is the world's largest manufacturer of data storage media. 3M core technology platforms include microreplication, injection molding, thin-film materials and processes, adhesives, and specialty chemicals and optoelectronics. The company's optoelectronics division is involved with blue lasers and fiber optics. Roughly 7.2% of 3M sales revenue is invested back into research; however, this percentage is much larger for research in optical storage.

3M has been involved with optical recording since the early sixties. 3M developed the first optical videodisk in 1963, resulting in 19 U.S. patents. At the time, 3M was a leader in magnetic storage products and saw optical storage as a long-term investment to protect its storage business. In 1983, 3M introduced the 12 in. and 5.25 in. write-once optical disks. In 1985, the company introduced CD-ROM services, mostly for software distribution, including data preparation, mastering, and disk production with a focus on fast turnaround time.

Also in 1985, 3M demonstrated the first commercial MO disk at COMDEX. In 1988, the company was first to market a 5.25 in. 650 MB ISO standard rewritable optical disk; and in 1993, it was first to OEM-qualify for 5.25 in., 1.3 GB ISO standard rewritable optical disks. This standard was codeveloped with IBM, Hewlett-Packard, DEC, and Fujitsu USA.

TECHNOLOGY DISCUSSION

Overall Process Review

The basic sequence of optical disk media fabrication involves an injection molded substrate with one side flat and the other stamped. The stamper is fabricated from glass and coated with a photoresist layer that is then patterned through a master for a suitable format. Nickel is then deposited on the stamper and patterned by lift-off. The stamper is used to transfer the format to each disk. After the stamping process, active thin films are put on the plastic disk substrates and finalized with a stack of seal coat and damping layer.

Mastering

3M mastering facilities are spread in Menemonie, Wisconsin, and Vadnais Heights, Minnesota. The company's strong point is the available flexibility and ability to master any format. 3M achieves state-of-the-art precision in track pitch accuracy and feature sizes. It uses automated photoresist processing as well as in-process testing. It also has extensive modeling capability for complete media structure. The JTEC team was shown the mastering control room, where an argon laser was used to record the master under computer control.

Replication

3M has multiple stamper-making technologies, including a galvanic stamper process that is the cheapest, a photo-polymer process, and a unique proprietary process. The photopolymer replication is used on video disks and large formats and is essential to multilayer disks. The injection molding technology is used in small-format products. Key issues to lower cost include increasing the number of disks stamped per stamper while reducing the number of defects. It was interesting to observe that the injection molding machines used at 3M were made in Japan, as was the resin used for the disks. 3M does not itself manufacture the state-of-the-art machines, but after purchasing machines from Japan, it modifies them to its needs and specs. The mold is seen as the critical component, since it needs to be matched to the injection machine. Molds are internally developed, based on experience with molds purchased from Japan.

The JTEC panel toured the company's injection molding facilities, which includes two Japanese injection molders.

Thin Films

3M was an early innovator in write-once technologies using bubble forming, ablative, and dye polymer materials. 3M was also a leader in the development of the MO media, with technical breakthrough first reported in 1983. It has a leading market position in current products in the United States, due to its sales force and willingness to work with its clients. The company has a strong patent position in the area of thin films and processes. 3M is committed to the migration of MO media and is actively pursuing research in innovative solutions such as direct overwrite, magnetic superresolution (invented at Sony), and materials for blue laser recording. The company has new growing programs in phase-change media, especially for write-once CD-R applications. R&D was also underway at the time of the JTEC visit on rewritable phase-change materials. It is interesting to note that a decision was made in 1982 not to pursue phase-change materials. Now 3M is late in the area of phase-change materials, where Matsushita and Asahi Chemical are the leaders.

The JTEC panelists also toured the thin-film deposition facilities, where three metal layers are deposited by a sequence of DC sputtering machines. A key issue was the introduction of the disks onto the system by human operators, which increases the risks of defects and slows down production. 3M anticipated automating this procedure in 1995. Another issue is the pumping down time during the outgas of the substrates. A key factor in increasing production speed is reducing pump time.

Chemical Coating and Components

3M plans to use the strength of its Specialty Materials Division in future products. For example, the company uses an antistatic hard coating (patent pending). It also has unique optical cartridge designs that provide high reliability in jukebox environments.

Testing

3M uses its internal expertise in test system technology in optics, electronics, software, coding, and channels. The company has internally developed test systems for materials characterization, mechanical testing, defect scanning, and dynamic performance characterization. 3M also leads the ANSI subcommittee on media lifetime.

The JTEC panel toured 3M's new Seika test lab and a defect analysis lab. Team members saw different recorders, some Japanese (Pulsetech)-made and some American (Apex)-made. Much of the media characterization was based on optical microscopy and relied heavily on the experience of the personnel.

Advanced Research

3M was first to demonstrate a blue-green laser diode. The company does not see itself in the laser business, but it wants to facilitate the storage market; however, 3M sees media fabrication compatible with blue lasers as an important issue. In MO systems, the birefringence of the substrate is a major source of background noise. Since birefringence increases with decreasing wavelength, the noise floor increases with the use of bluer lasers. From this point of view, phase-change media might offer some advantages, since it does not rely on polarization modulation but on reflectivity change. 3M is collaborating with Philips and IBM under U.S. government funding for the commercialization of blue-green diodes. R&D for blue-green optical media is also underway.

DISCUSSION

During discussions, Dr. Steven Webster discussed possible technology migration directions. The key emerging markets for optical technology could be video storage and a replacement for current diskette technology. For video applications, 3M is collaborating with Sony and Philips for a 6.6 GB HD-CD that will use MPEG-2 compression. He also described the smart disk concept that was originally put forward by Ogawa with the coined buzzword "MO-ware," where applications for different computer platforms and the user's data files are stored on one disk. The user can then create his entire computing environment anywhere he carries this disk.

For several years the business was slow in growing, and companies were conserving their capital; however since 1993, the business has been growing, and 3M has taken measures to build up production capacity.

Three important steps are being taken during the design of increased production capacity:

  1. automate substrate inspection and automated loading (incrementally invested)
  2. develop new thin-film process to reduce pumping times
  3. address high-volume issues

3M representatives indicated that they appreciate the government funding to get ahead of the curve, and felt that TRP was a good vehicle to both reach this goal and to convince upper management.


Published: February 1996; WTEC Hyper-Librarian