Wafer Production Process

- Mar 13, 2019-

Wafer process is in a big way, wafer production includes two steps: ingot manufacturing and wafer fabrication. It can be subdivided into the following main processes (in which the ingot manufacturing only includes the first process below, All of the rest are wafer fabrication, so they are sometimes collectively referred to as the crystal column post-processing process).


Wafer production process


In a big way, wafer production involves two major steps: ingot manufacturing and wafer fabrication. It can be subdivided into the following main processes (in which the ingot manufacturing includes only the first process below, and the rest of the genus Wafer manufacturing, so sometimes they are collectively referred to as crystal column post-processing steps):


Ingot Growth - Ingot Polishing and Inspection -- Outer Diameter Grinding -- Slicing -- Round Edge -- Surface Grinding -- Etching -- De - rubbing -- Polishing -- Cleaning -- Inspection -- Packaging


1, crystal rod growth process: it can be subdivided into:


1) Melt Down: The block-shaped high-purity polycrystalline silicon is placed in a quartz crucible and heated to a melting point of 1420 ° C or higher to completely melt it.


2) Neck Growth: After the temperature of the silicon melt is stabilized, the seed crystal in the direction of <1.0.0> is slowly inserted into it, and then the seed crystal is slowly lifted upward to reduce the diameter to A certain size (generally about 6mm), maintain this diameter and stretch 100-200mm to eliminate the difference in grain alignment orientation within the seed crystal.


3), Crown Growth: After the neck is finished, slowly reduce the lifting speed and temperature, and gradually increase the diameter of the neck to the required size (such as 5, 6, 8, 12, etc.).


4), Body Growth: continuously adjust the lifting speed and melting temperature to maintain a fixed ingot diameter until the length of the ingot reaches a predetermined value.


5) Tail Growth: When the length of the ingot reaches a predetermined value, the lifting speed is gradually increased and the melting temperature is increased, so that the diameter of the ingot is gradually reduced to avoid the phenomenon of displacement and slip due to thermal stress. Produced, eventually completely separating the ingot from the liquid surface. A complete ingot is obtained.


2, cutting and inspection (Cutting & Inspection): the length of the ingot is removed from the head and tail part of the smaller diameter, and the size is tested to determine the process parameters of the next step.


3. Surface Grinding & Shaping: Due to the deviation of the outer diameter and the roundness of the ingot during the growth process of the ingot, the outer cylindrical surface is also uneven, so the outer diameter must be trimmed and ground. Make the size and shape error less than the allowable deviation.


4. Wire Saw Slicing: Since the hardness of silicon is very large, in this process, the ingot is cut into a piece of sheet by a ring-shaped saw blade with diamond particles embedded in the inner diameter edge.


5. Edge Profiling: Since the outer edge of the wafer that has just been cut is sharp, the silicon single crystal is a brittle material. In order to avoid the cracking of the wafer, the strength of the wafer is damaged, the surface of the wafer is damaged, and the particles are contaminated in the subsequent process. The edge and outer diameter dimensions of the wafer must be automatically trimmed with a dedicated computer control device.


6. Lapping: The purpose of grinding is to remove the saw marks and breakage on the surface of the wafer during cutting to achieve the desired finish of the wafer surface.


7. Etching: A chemical etching method is used to remove a damaged layer on the surface of the wafer due to processing stress after processing in the previous processes.


8. Gettering: The bottom half of the wafer is felt by sand blasting to facilitate subsequent processing. 9. Polishing: Polishing the edges and surfaces of the wafer to further remove the particles attached to the wafer, and to obtain excellent surface flatness, which is beneficial to the wafer processing process to be described later. .


10. Cleaning: The finished wafer is thoroughly cleaned and air dried.


11. Inspection: Carry out the final comprehensive inspection to ensure that the product finally meets the specified specifications such as size, shape, surface finish and flatness.


12. Packing: Separate, package, and pack the finished product with flexible materials, and send it to the following chip manufacturing workshop or factory to order customers.