From the beginning of production to the completion of the manufacturing of semiconductor products, there are mainly two processing processes, which are called front-end production and back-end production. Although MOSFET is a relatively simple semiconductor device, it also needs to go through these two production processes.

　　Front-end production mainly refers to wafer manufacturing, including complex processing steps such as photolithography, plasma etching, ion implantation, ion diffusion, oxidation, evaporation, vapor phase epitaxial growth, sputtering, and chemical vapor deposition. The purpose of these processing steps It is mainly to create a full-featured die on a silicon wafer. The electrical performance of each die is verified by a wafer test platform built by a probe station and automatic test equipment. The die that fails the test will be The dots are dotted as unqualified marks. These marks will be recognized in the subsequent production, and the dies with dots will not be processed. Since the wafer is called Wafer or Die, the test on the die is also It is called Wafer Sorting or Die Sorting.

　　Back-end production mainly refers to packaging and testing, that is, through processing, the die is made into the style we usually see. After the product is packaged, it needs to be tested again to verify the electrical performance of the product to ensure that the finished product can meet the product specifications. This test belongs to the last process of subsequent production and the last step of the entire production process, so it is called the final test, or Final Test. A brief introduction of the packaging and testing preparation process is as follows:

　　1) Wafer Sawing.

　　Use a high-speed rotating dicing knife to cut and separate the dies on the wafer.

　　2) Die Attach.

　　The silver glue sticks the die to the predetermined position of the lead frame.

　　3) Wire Bond.

　　Between the solder joints of the die and the pins of the lead frame, a thin metal wire is soldered to establish the connection between the die circuit and the outside.

　　4) Molding.

　　Place the lead frame with the die bonded and the fused wire into the die-casting mold, and then press the molten resin plastic into the die to wrap the entire die according to the packaging requirements.

　　5) Trim and Form.

　　Cut off the excess connecting material of the lead frame, and shape the pins into the required shape according to the packaging form of the product.

　　6) Final test, Final Test.

　　Test whether the performance of the product meets the requirements. The product that passes the test is considered a qualified product

   　Although, in each packaging process, there are certain process control methods and quality monitoring methods, but there are still some difficult-to-control defects that are introduced into the product. So when the product is packaged, it needs to be tested to identify the quality of the product. In terms of test items and test methods. The difference between Wafer Sorting and Final Test is not big, but the final test is the last step of the entire production process. The role of product quality control is more important.