What is the effect of defects on the electrical properties of semiconductors? Advantages of using X-ray to detect internal defects

Date：2021-09-13 15:12:00Views：1220

When a small amount of impurities are doped into a semiconductor, the periodic potential field near the impurity atom is disturbed, forming an additional bound state and generating an additional impurity level in the band gap. The impurity that can provide electron carriers is called donor impurity, and the corresponding energy level is called donor energy level, which is located above the forbidden band and near the bottom of the conduction band.

What is the mechanism of impurities and defects affecting the electrical properties of semiconductors? Donor and acceptor impurities can provide carriers and improve conductivity; Non donor and acceptor impurities often produce recombination centers and shorten the service life of non-equilibrium carriers; Defects are usually composite centers. Various impurities and defects can scatter carriers and reduce mobility and conductivity.

The main effect is to accurately control the number of free electrons and holes. In short, the more impurities, the worse the accurate control of free electrons and holes in physical materials. The difference will lead to the decline of physical indexes: stray current increases with the increase of ambient temperature; The voltage resistance and temperature coefficient of PN junction become worse.

IGBT semiconductor module is one of the most common electronic components in electronic manufacturing. Low frequency and high power electronic components, which are bridged and encapsulated by IGBT and FWD through specific circuits, are widely used in welding machines, inverters, frequency converters, point solution power supplies, ultra audio induction heating and other fields. So how to ensure that the IGBT semiconductor module is a good product, and ensure that the defective IGBT semiconductor cannot flow to the next process, so as to improve the production cost and enterprise efficiency. During the operation of IGBT semiconductor packaging module, the technology is complex. However, how to identify and test packaging has become the most helpless process for enterprises. With fierce market competition and continuous improvement of product quality standards, greater efforts are needed for cost control, which is also an urgent problem to be solved in IGBT semiconductor packaging industry.

At present, there are many detection methods, but X-ray detection method is more and more popular in the market. It uses X-ray to directly penetrate the product surface and directly perspective the internal structure of the product. Through the analysis of the internal structure of the product, it can quickly lock the defect location and the size of the damaged area.

X-ray can visually observe whether there are bubbles and other defects in IGBT semiconductor module, and use the X-ray transmission principle to detect IGBT module, which is fast and accurate. When the X-ray detection equipment transmits the IGBT module, you can directly observe whether there are bubbles and other defects in the IGBT module, or directly observe the location of the defects. The use of X-ray has a multiplier effect on enterprises.