Uses of tungsten hexafluoride (WF6)

Tungsten hexafluoride (WF6) is deposited on the surface of the wafer through a CVD process, filling the metal interconnection trenches, and forming the metal interconnection between layers.

Let’s talk about plasma first. Plasma is a form of matter mainly composed of free electrons and charged ions. It exists widely in the universe and is often regarded as the fourth state of matter. It is called the plasma state, also called ” Plasma”. Plasma has high electrical conductivity and has a strong coupling effect with electromagnetic field. It is a partially ionized gas, composed of electrons, ions, free radicals, neutral particles, and photons. The plasma itself is an electrically neutral mixture containing physically and chemically active particles.

The straightforward explanation is that under the action of high energy, the molecule will overcome the van der Waals force, chemical bond force and Coulomb force, and present a form of neutral electricity as a whole. At the same time, the high energy imparted by the outside overcomes the above three forces. Function, electrons and ions present a free state, which can be artificially used under the modulation of a magnetic field, such as semiconductor etching process, CVD process, PVD and IMP process.

What is high energy? In theory, both high temperature and high frequency RF can be used. Generally speaking, high temperature is almost impossible to achieve. This temperature requirement is too high and may be close to the sun’s temperature. It is basically impossible to achieve in the process. Therefore, the industry usually uses high-frequency RF to achieve it. Plasma RF can reach as high as 13MHz+.

Tungsten hexafluoride is plasmaized under the action of an electric field, and then vapor-deposited by a magnetic field. W atoms are similar to winter goose feathers and fall to the ground under the action of gravity. Slowly, W atoms are deposited into the through holes, and finally filled Full through holes to form metal interconnections. In addition to depositing W atoms in the through holes, will they also be deposited on the surface of the Wafer? Yes, definitely. Generally speaking, you can use the W-CMP process, which is what we call the mechanical grinding process to remove. It is similar to using a broom to sweep the floor after heavy snow. The snow on the ground is swept away, but the snow in the hole on the ground will remain. Down, roughly the same.