Manufacturers of compound semiconductors look for every opportunity to improve process or yield. HÜTTINGER discusses the energy supply needs for manufacturers and decide that efficiency and robustness are the main requirements for power supplies in semiconductor production.

The semiconductor industry is constantly faced with significant change as the industry continues to scale devices and develop new manufacturing techniques. Extreme fluctuations in supply and demand, merciless price wars and short innovation cycles contribute to continual pressure on companies. To remain competitive, companies must be flexible, innovative and constantly find new methods to keep production costs down.

Power supplies are used in various steps of semiconductor production and have to be able to keep pace with any changes as well as contribute to productivity with any changes themselves.

German company HÜTTINGER has a strong understanding of power supply needs and have introduced the high-frequency generator TruPlasma RF1003 they feel offers an innovative power supply that keeps abreast of the challenges for the compound semiconductor industry. The new device has been developed with a robust approach to providing energy efficiency and the company hopes to set new standards for such devices.

HÜTTINGER has also developed the ideal solution for cutting-edge trench-filling process using HIPIMS (high power impulse magnetron sputtering). DC generators from the TruPlasma Highpulse Series 4000 are designed to reliably and accurately supply the necessary energy for these processes.

In fabricating IC circuits, thin layers of materials are applied to a wafer’s surface and required structures are constructed. The layering and etching processes often use plasma sources due to high production qualities. To deposit amorphous silicon (a-Si), micro crystalline silicon (μc-Si), SiO2 and SiNx onto the wafer, PECVD (plasmaenhanced chemical vapor deposition) processes are used. HÜTTINGER developed the TruPlasma RF 1003 especially for this purpose. This power supply produces outputs ranging from 1 watt to 3000 watts at a frequency of 13.56 megahertz, in addition to PECVD, it also reliably supplies precise power for etching processes.



Above: HE_2313 The power supply generating the plasma is a key component of plasma based processes

 

The TruPlasma RF 1003 has new power combiner technology, called CombineLine, that allows extreme stability for processes.



Above: TruPlasma RF 1003

 

CombineLine delivers a 50-Ohm output impedance from the power supply, enabling CombineLine to adjust the process optimally at any time. Adjustment networks keep the process constant at an impedance of 50 Ohm. When ideally adjusted, the optimum HF output is introduced into the process.

However, in actual plasma processes, fluctuations always occur that change plasma impedance. The connected matchboxes can react during a limited error adjustment time and re-establish the 50-Ohm state in a matter of seconds. During the error adjustment phases, reflected outputs flow back to the power supply, calling for a quick, precise surge in the power output to hold the energy input steady for the plasma. The reflected output needs to be absorbed into the power supply without damaging it.

This can be done as the combiner technology has a dedicated absorber that can continuously deflect an output of 600 watts. For short-term total reflections of output (short circuit with up to 3 kilowatts of reflected output), the internal components are sufficiently shielded to ensure no damage occurs and that the power supply is operating at the highest plasma stability. CombineLine ensures the defined output is accurately delivered by means of a very broad impedance range.

The results are stable processes for all output ranges. Deposition and etching processes are supplied with precise processing energy required which allows less energy to be used while achieving reproducible results and a higher yield.

An additional benefit of the TruPlasma RF 1003 is an efficiency factor level of more than 80 percent. Due to this efficient energy conversion, the generator is able to reduce energy costs for the user. The source of this high energy conversion level is a special design for internal HF switching phases.

The D converter class employs an optimally adjusted conversion principle produced by interconnecting the high-performance MOSFETs and a low-loss output network. The power supply therefore makes a major contribution to energy efficiency, protecting the environment as well as the customer’s bottom line.

With its compact housing in a half 19” design (216 mm x 133 mm x 381 mm), the TruPlasma RF 1003 is ideal for system integration in plasma deposition tools. The CombineLine technology provides a choice of cable length for connecting the matchbox and processing chamber that makes integration unbelievably easy and sets new benchmarks for efficiency.

HIPIMS generators for efficient and high-level trench-filling

Trench-filling with the help of HIPIMS processes is a cutting-edge process in semiconductor manufacturing. As semiconductors become smaller and smaller, the depthwidth ratio of the film layers applied to the wafer changes. This change is making it increasingly difficult to fill the trenches. The use of HIPIMS processes makes it much easier to do this.

The essential difference between DC and HIPIMS plasmas is the percentage of ions in the sputtered material. While no ionization occurs in DC plasma, HIPIMS plasma has an ionization rate of up to 90 percent – the result of highly energetic pulses in the megawatt range from the HIPIMS power supply. Ionized particles lead to other mechanisms in growing layers. Moreover, an ionized particle stream with a calculated bias voltage travels directly to the substrate. This is how high filling grades are achieved on uneven substrate surfaces for targeted deposition.

The TruPlasma Highpulse Series 4000 from HÜTTINGER offers the right power supply for both the lab and volume production plants. Pulse outputs from 1 megawatt to 8 megawatts allow for a broad range of scaling. And with little effort, conventional DC cathodes can be run with the HIPIMS power supply, so the new process can be tested and future volume production implemented.

Summary

The use of innovative power supplies offers clear advantages in semiconductor production. Whether for deposition by means of PECVD or for trench-filling through HIPIMS, modern generators provide for stable processes, an increased film quality and fewer defects. They reduce costs considerably and make production processes more efficient, thus contributing to easing price pressures in the semiconductor industry and creating a competitive advantage for companies.



Above: Schematic set up of HIPIMS