Semiconductor process equipment provides a manufacturing foundation for large-scale semiconductor manufacturing. Moore's law, which depicts the prospect for the electronics industry, will surely lead to a higher degree of integration and miniaturization of semiconductor devices and stronger functions in the future. Here we will first introduce the first step of semiconductor technology - the single crystal furnace for single crystal drawing.

Single crystal furnace

Single crystal furnace, a fully automatic Czochralski single crystal growth furnace, is a device that uses a graphite heater to melt polycrystalline materials such as silicon in an inert gas (mainly nitrogen and helium) environment, and grows dislocated single crystals using the Czochralski method.

There are two naming methods for single crystal silicon furnace models, one is the feeding amount and the other is the furnace chamber diameter. For example, models such as 120 and 150 are determined by the feeding amount, while 85 furnaces refer to the diameter of the main furnace barrel.

The main structure of a single crystal silicon furnace consists of three main parts: a host, a heating power supply, and a computer control system.

Single crystal silicon wafer process flow

Silicon, Si, there are many things on Earth that contain silicon, and it seems that over 90% of them are crystalline silicon, which is also known as monocrystalline silicon. Solar grade silicon with a purity of over 6N is sufficient.

At the beginning, it was a stone (which contains silicon). The stone was heated to a liquid state, and then heated to a gaseous state. The gas was passed through a sealed large box, which had more than N sub crystals heated and clamped with graphite at both ends. The gas passed through this box, and the sub crystals would absorb one of the gases onto the sub crystals. The sub crystals gradually became thicker because it was the gas that became solid, so it was very slow, about a month, There are many long native polycrystalline silicon in the box.

Single crystal silicon wafers enter the production process as follows:

1. Pickling: use dilute nitric acid HNO3 to clean, remove surface impurities and Silicon tetrachloride produced during refining.

2. Cleaning: Clean the residual impurities in the silicon material after acid washing.

3. Drying of monocrystalline silicon material: removing moisture.

4. Pick material: Distinguish between P-type and N-type silicon materials.

5. Ingredients: Match the type of silicon material used for crystallization.

6. Single crystal furnace crystallization:

7. Silicon rod detection: Check for dislocations, broken edges, and other phenomena.

8. Breaking: Cut a single crystal silicon rod into a square shape using a band saw blade.

9. Packaging: Pack the broken single crystal silicon rod and send it to the next process

10. Rounding: Grinding a single crystal silicon rod at four right angles.

11. Multi wire cutting: Switzerland's 264265. Japan's PV800 and MDM442DM equipment cut 0.33mm.

12. Cleaning:

13. Single crystal silicon wafer detection:Structure of Single Crystal Furnace

The single crystal furnace body (including the furnace bottom plate, main furnace chamber, furnace cover, isolation valve chamber, auxiliary furnace chamber, seed crystal lifting and rotating mechanism, and crucible lifting and rotating mechanism) is made of 304L stainless steel. All chambers have undergone defect furnace room inspection and flaw detection, and have undergone 0.6MPa water pressure test and helium mass spectrometer leak detection.

1、 Main furnace structure

1. Base and furnace bottom plate

The bottom plate of the furnace is designed as a flat plate, with a double-layer structure and water cooling. Four electrodes pass through the bottom plate, and there is a water-cooled flange area at the corrugated pipe connection of the crucible lifting mechanism.

2. Main and lower furnace rooms

The main and lower furnace chambers are double layered cylindrical structures