The Basic Investigation Of Thermal Spectrum Analysis Method Of Transistor

Reliability analysis is a comprehensive technology which developed from 1950s. It has already entered into a mature stage in 1970s. Now, with the IT era, because the complexity of microelectronic devices continue to increase, their using condition becomes more and more difficult, and their position in the power system can not be replaced, the reliability analysis of microelectronics devices have already catched more and more attention. For the power semiconductor devices in high-voltage direct current power transmission, high-speed trains and electric vehicles, phased array radar, semiconductor lasers, electric power systems and so on, when they are in power dissipation, the junction temperature distribution is generally non-uniform, while the uniform property of generational heat, temperature distribution and peak temperature are major factors which can affect the thermoelectric properties, stability and reliability of the devices. It is an important factor whether the temperature distribution is uniform or not, which influences the thermal performance, electrical performance, reliability and life time of semiconductor devices. To aviation and military field, the significance of property is also not fluctuated.Currently, thermal infrared method, simply signed as TIM, is the most accurate method to detect temperature distribution of microelectronics devices, i.e. But the disadvantages of this approach are obvious. Fist, the thermal infrared imager is very expensive; second, this method is generally used in reliability analysis of semi-finish devices, for the measurement of encapsulated finish devices, images must be taken after the devices are dissected. Thus, the measurement is destructive, even the measurement could not be implemented after destruction; finally, thermal infrared method cannot complement qualitative and quantitative analysis specifically for the device active region. Therefore, this method is not suitable to be a conventional measurement. Electrical method, used to measure both finish and semi-finish devices, is nondestructive and without damage in measurement to be extensively used as technology standard method. The electrical method, adopted in international IEC standard to detect device temperature, is called standard electrical method, simply signed as SEM. In the standard method, uniform temperature distribution of device is hypothesized, and only single temperature is used to characterize temperature information of the whole device, which is called standard-electrical temperature Ts. Due to good operability, convenient measurement, and simple comparison & estimation based on only one parameter, standard electrical method is always popular in the world. However, its demerits are obvious that it obliterates and covers up the non-uniform property of temperature distribution, and easily causes misjudging and leaked judgment.The main content in this paper, thermal spectrum analysis method of transistor is a pure electrical method to detect chip temperature distribution. It inherits the main merits of standard electrical method which can measure the junction temperature non-destructively. At the same time, it is of the key advantages of thermal infrared method which can obtain the information of peak temperature, and non-uniform property & non-uniform degree of junction temperature. This approach can also present the temperature and effective area by measuring the relevant parameters of the device active region. Combining with the corresponding mathematical model, the junction temperature distribution can finally be calculated. Thermal spectrum analysis method is expected to solve the scientific problem which has plagued all the world for decades and makes it possible to detect the temperature distribution by electrical method. So it is very significant and of great value to the temperature reliability analysis of microelectronics devices.In the first chapter "introduction", it's pointed out that both the infrared image method and standard electrical method have their own disadvantages when served as reliability analysis method. Then, the fact that the standard electrical method has its insurmountable shortcomes is also particularly explained. Finally, the research background of using pure electrical method to detect non-uniform degree of junction temperature and the achivement of thermal spectrum analysis method are illuminated.In the 2nd chapter "The measurement, fitting, and checkout of V-I-T background data of PN junction devices", the measuring method of background data is innovated, and the background data quality is greatly improved by using shockley equation to fit it. At the same time, it is found that in Semi-logarithmic coordinates, the value of (?) will increase with the increasing current. This is the true reflection of I-V characteristic of PN junction.In the 3rd chapter" the climb peak effect of low current of PN junction", the original experiment level is really exceeded. The excessive thermotaxi effect of low current are again proved to be a real scientific rule in PN junction by using new sample and pure experimental method. At the same time, we get a deep understand to it, and put out the concept of climb peak effect of low current. This concept can perfectly explain the phenomenon that Ts will be different corresponding to Im, and the temperature will decrease while the measuring current increases. So the climb peak effect of low current is of great significance to the reliability analysis of semiconductor devices.In the 4th chapter "The thermal spectrum analysis based on sub-transistor model", the truth that the temperature distribution is not uniform when the PN junction devices are dissipating power reappeared by using sub-transistor model innovatively. Then, each I-V data detected when the temperature of PN junction is non-uniform is analysed by using thermal spectrum analysis method, and the software of thermal spectrum analysis method is also fully checked via comparing the thermal spectrum analysis result and the detect value of temperature. Finally, we point out that the peak temperature and effective area which are obtained by this approach is scientific and of practicability.In the 5th chapter, the scientific effort and achievements in the whole under graduate period are generalized. The foreground and trend of development in future are expected and evaluated, and the research work proposal in future is presented finally.