Magnetron Sputtering System

One of the tools in the clean room at CIDESI Querétaro is a magnetron Sputtering system, from Angstrom Engineering, this system is used for research projects and manufacturing of sensors and integrated circuits, see Fig .1. It is important to know that the deposit technique known as “Sputtering” or cathodic erosion, is among the best methods for obtaining materials with specific characteristics, due to its reproducibility, scalability and versatility of processes that can be carried out in this system, for this and more, is among the favourite of the metallization area in the clean room of CIDESI Querétaro.

The magnetron sputtering system located at the clean room facilities at Cidesi Queretaro is used to deposit materials such as semiconductors, dielectrics and metals which are used during the fabrication of sensors and integrated circuits.

Magnetron Sputtering System and Material Deposition Process

In a Sputtering deposition process, the main chamber, where the materials are deposited, is evacuated until high vacuum is reached, commonly, pressures less than 2 x 10-6 Torr are achieved. The Sputtering at CIDESI Querétaro cleanroom works with a mechanical pump and a turbo molecular pump to reach this base pressure. After the base pressure is reached, the deposition starts when an ionizing gas, in this case Argon, which flows into the chamber. In this step, both the pressure and the argon flow are regulated until the deposition pressure is reached, typically, in the mTorr range, this Argon gas helps to form the plasma. It is important to know that reaching a high vacuum inside the chamber is important to reduce the partial pressures of gases from undesirable elements that can potentially contaminate the materials that are being deposited.

The Sputtering deposit technique is among the physical deposition techniques in vapor phase. The physical principle of operation of a Sputtering system consists of the generation of a plasma, which will be obtained by applying a potential between a cathode and an anode, subsequently, electrons in the Argon gas are accelerated in the opposite direction to the cathode, which causes collisions of these electrons with the Argon atoms. These collisions generate an electrostatic repulsion, and promote the ionization of the Argon gas, due to the knock off of electrons from the atoms of the Argon gas. Commonly, the cathode is in contact with the material to be deposited and the anode is connected to the sputtering chamber, acting as an electrical ground. At this point, the positively charged ions are accelerated towards the cathode, which is negatively charged, which causes high-energy collisions on the target surface, and each of these collisions causes atoms on the surface of the material to be ejected with enough kinetic energy so that these travel from the target and are deposited on a substrate, all this, in a partial vacuum inside the deposit chamber. The ionizing gas, which is commonly Argon or Xenon, are selected and used for being a high molecular weight gas.

The figure shows the Aluminum deposition, the purple color is the Argon ion plasma inside the chamber of the magnetron Sputtering at the cleanroom facilities at CIDESI Querétaro.

Deposition and co-deposition of materials in a magnetron Sputtering system

The Sputtering of the cleanroom at Cidesi Querétaro is able to carry out co-depositions and continuous deposition processes of materials without loss of vacuum in the main chamber, thanks to its two DC and one RF sources. This tool allows it to be carried out from a deposition or up to three deposits of materials at the same time which gives incredible advantages and possibilities in the manufacture and design of materials

The Sputtering deposition system at CIDESI Querétaro clean room can carry out depositions and co-depositions processes up to three materials at the same time. The tool has two 1000 W DC and one 600 W RF sources

The main capabilities of Sputtering system at Cidesi cleanroom are:

  • Spinning and warming of the sample holder up to 50rpm and 650°C respectively.
  • Simultaneous coating of up to three 4 inches wafers.
  • The coating may be controlled by software (PID control), where the coating rate is monitored in angstrom/second.
  • The coated film thickness is monitored by inficon sensor.
  • Finally, the apparatus is supported by a mechanical pump and a turbo molecular pump that allows it to reach base pressures up to 5x 10 ^-7 Torr, with the objective of avoiding the pollution of the materials that are being coated.

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