Zone refining is the process used to obtain super pure silicon. It involves the purification of a solid material by passing it through a molten zone. This method is commonly used in the semiconductor industry to produce high-quality silicon for the manufacturing of electronic devices.

Here is a detailed explanation of the zone refining process and why it is the correct answer:

1. Introduction to Zone Refining:
Zone refining is a technique that takes advantage of the difference in solubility between impurities and the desired material. In this case, impurities are removed by selectively melting and solidifying the silicon.

2. Principle of Zone Refining:
The principle behind zone refining is based on the fact that impurities tend to have a higher solubility in the molten state compared to the solid state. When a molten zone is passed through the silicon rod, impurities dissolve in the molten zone, while the pure silicon solidifies behind the zone.

3. Process of Zone Refining:
The process begins with a silicon rod that contains impurities. The rod is placed in a high-temperature furnace, and a localized molten zone is created by heating a small section of the rod using an induction coil or a high-intensity light source. As the molten zone moves along the rod, impurities dissolve into the molten zone.

4. Impurity Removal:
As the molten zone passes through the silicon rod, impurities are gradually removed. The impurities are carried away with the molten zone, leaving behind a region of highly pure silicon. This process is repeated multiple times to further purify the silicon.

5. Advantages of Zone Refining:
Zone refining offers several advantages for the purification of silicon:
- High purity: The process can achieve extremely high levels of purity, often exceeding 99.9999%.
- Selective impurity removal: The method allows the selective removal of specific impurities, resulting in precise control over the final purity of the silicon.
- Scalability: Zone refining can be scaled up for industrial production, making it suitable for large-scale manufacturing processes.

In conclusion, zone refining is the most suitable method for obtaining super pure silicon. It effectively removes impurities from the silicon by selectively melting and solidifying the material. This process is widely used in the semiconductor industry to produce high-quality silicon for electronic devices.