I'm planning to go very simple for the DC sputtering source as well, basically a Variac driving a high voltage transformer, high voltage bridge rectifier, some caps and that's pretty much it. Seems like the basic manual commercial ones are pretty similar. All pretty familiar from my time building tube amps...
A sputtering power supply built in the 1970's consisted of a 3 phase SCR fed 240 volt to 1000 volt transformer with optional output taps at 750 volts and 500 volts. The transformer output was fed to a 3 phase rectifier, a small capacitor and then through a large inductor. There was also a set of metal oxide varistors connected to the output.
The inductor was required to limit the current to the sputter source target during the frequent arcing events. The SCR controller ran at line frequency to regulate output voltage and was useless for limiting the arc current. The varistors limited the damage to the power supply when the inductor voltage peaked during a arc. These early power supplies were used because nothing else was available at the time. A arcing event would frequently destroy the substrate being coated. The power supplies can be found at junk yards and are priced based on their copper content.
By the late 1980's the SCR power supplies had been replaced with compact light weight switching power supplies with milli second arc shutoff response times , very low stored energy, and control logic for delays in turning the power back on.
By 1995, these supplies were replaced by mosfet based power supplies with micro second shutoff times and even lower stored energy.
Around 2000, the power supplies were replaced by switchers which allowed the user to program a positive voltage pulse running at a duty cycle to prevent a arcing event from occurring. This last improvement has allowed significantly faster sputter deposition times.
The current generation of power supplies introduced in 2015 has increased reliability and additional control of the voltage pulsing.
Making your own power supply is a waste of time. You can buy a 1990 vintage 5 kw Advanced Energy sputter switching power supply for $300 on EBAY. The faster response time early ENI power supplies are also available. at low cost.
These supplies are obsolete by current standards and the price reflects that status. The switching power supplies are a consumable in industry. The earlier models used transistors rather than mosfets and were very complicated and difficult to repair. The newer supplies have fewer and more durable components.
The design of DC sputtering sources has also undergone several generations of design improvements. The improvements are driven by the need for better deposition rates, better substrate film uniformity, better target utilization, fast turn on time and optimum film growth. Some sources have modified magnetic fields to direct ionized as well as electrically neutral particles to the substrate to control the film growth.
The sputter sources may look simple and easy to make. They are not.. A afternoon spent reviewing the online patents will give you a better idea as to what is involved.
Modern DLC coatings are produced using cathodic arc sources rather than sputter sources. In the past these films have been made using ion beam sources or by plasma enhanced chemical vapor deposition. The basic requirement is a source of ionized carbon. Sputter sources produce primarily electrically neutral particles. Their use is limited to depositing carbon films. An example of this application is the carbon film applied to disc surfaces in magnetic storage. The thin film prevents damage to the read head when there is unintended contact with the disc.
There have been major improvements in DLC film quality in the last few years. Kyocera, among others, now offers a DLC coating service in the US. A large batch arc deposition coater is about 3 feet in diameter and four feet tall. The interior contains several vertical rotary planetary substrate holders. One of these machines can process a batch of several thousand inserts. You will find that the cost of the coating service is modest compared to what you are about to spend in an attempt to recreate a DLC coating that was obsolete 30 years ago.
Balzers made the transition from sputter systems to arc deposition systems about 5 years ago. The coating time for a multilayer tool coating went from 12 hours to 6 hours with improved film properties.
Coating - KYOCERA UNIMERCO
One more comment:
The base pressure of a sputtering system is in the 1.0 E-6 torr range or lower. The low base pressure is required to remove reactive gases such as oxygen from the chamber before sputtering can begin
The base pressure can be achieved more rapidly with heat , UV light, or a glow discharge dislodging the oxygen or water vapor stuck to the chamber walls, fixtures, and substrates.
Oil contaminated substrates can be cleaned prior to coating in a oxygen glow discharge.
Sputtering gas pressures are in the 1 to 5 E-3 torr range. Sputtering is done with a continuous Argon supply in the 10 to 100 sccm range depending on chamber size with the high vacuum pump running continuously to flush out the reactive gasses in the chamber.
My knowledge on this subject is from the 1990's. Things may have changed in the last 20 years.
This was something that started as a skunkworks project and has become much higher priority because of a vendor issue unfortunately...
unfortunately there aren't many other vendor options around here.
