| As human society entering the information age,semiconductor microelectronic technology is becoming more and more important in the development of social and economic in human social.Electronic components,such as integrated circuits and power devices are the industrial foundation of the current information society.Compared with integrated circuits,the power device is characterized by high voltage and high current,which is the core device of electric energy conversion in the power electronic system.Silicon-based PIN power diode is a basic electronic component,which is mostly used in consumer electronics,green lighting,security and communication,automotive electronics,smart grid,aerospace and other fields.Generally,electrical performance is an important index to measure PIN power diode.With the development of intelligent,integrated,miniaturized and low power consumption of electric energy conversion system,the requirements for PIN power diode are becoming more and more strict.Czochralski(CZ)monocrystalline is the most widely used monocrystalline material,which has an important impact on the electrical performance of PIN power diode.It is of great significance to study the effects of oxygen impurities and carbon impurities in Czochralski(CZ)monocrystalline silicon on the electrical properties and the micro mechanism of PIN power diodes.In this paper,the effects of oxygen and carbon impurities in Czochralski silicon on the performance of PIN rectifier diodes and their mechanism are studied from devices to materials,not only macroscopically and microscopically,but also in phenomenon and essence.We prepared silicon wafers and PIN rectifier diode samples with different initial oxygen and carbon concentrations,including the electrical performance testing,optical observation of defect corrosion in the intrinsic region,Fourier transform infrared spectroscopy testing,TEM testing,EDS testing,electron diffraction,deep level transient spectroscopy testing and other analysis methods.Combined with the relevant theoretical analysis and the research of the first principle calculations,the following results are obtained.(1)The effects and correlation of oxygen impurity in Czochralski(CZ)monocrystalline silicon on the electrical properties of PIN rectifier diode were studied.The results showed that the yield of PIN diode decreases with the increase of initial oxygen content.The reverse leakage current(IR)is increased from 0.1 μA to 0.575 μA with the increase of initial oxygen content,which showed a kind of exponential curve with the increase.The reverse withstand voltage(VB)and the time of reverse recovery(TRR)showed a certain downward trand with the increase of initial oxygen content.There was little correlation between the drop of forward voltage(VF)and the initial oxygen content.The oxygen impurity content of 9.70 ×1017at/cm3 is the critical concentration of oxygen impurities.Below this concentration,oxygen impurities have little influence on the electrical performance of pin rectifier diode,and on the contrary,they have more influence on the electrical performance of the device.(2)The effects and correlation of carbon impurity in Czochralski(CZ)monocrystalline silicon on the electrical properties of PIN rectifier diode were studied.The results showed that when the carbon content changed from 0 to 3.00×1017 at/cm3,there was a strong correlation between the carbon content and the electrical performance of PIN rectifier diode,which represented the electrical performance of the device to decrease,the yield of PIN diode to decreases significantly,the reverse withstand voltage of PIN rectifier diode to decrease and the reverse leakage current(IR)of PIN rectifier diode to increase significantly.The drop of forward voltage increased,the time of reverse recovery(TRR)decreased,the overall electrical performance of the device decreased significantly.The carbon impurity content of 6.10×1016at/cm3 was the critical concentration.When it was below this concentration,carbon impurities had little influence on the electrical performance of PIN rectifier diode,on the contrary,it had greater impact on the electrical performance of the device.Compared with the change of oxygen content,the change of carbon content has more obvious influence on the electrical performance of PIN rectifier diode.(3)The mechanism oxygen impurities in Czochralski(CZ)monocrystalline silicon in the electrical performance of PIN rectifier diode was studied.The reason of the influence on the electrical performance of the device was the bulk oxidation-induced stacking faults(B-OSF)in the intrinsic region of PIN rectifier diode.Due to the action of interstitial oxygen and supersaturated self-interstitial silicon atoms SiI in Czochralski monocrystalline silicon,oxygen precipitation was formed after high temperature diffusion in the device,as it caused the volume strain of the silicon matrix in the intrinsic region.The aggregation of selfinterstitial silicon atoms SiI in the stress region produced the bulk oxidation-induced stacking faults(B-OSF),which were mainly dislocations,a small amount of stacking faults,and increased with the increase of the initial oxygen content.The B-OSF defects would produce the "impurity piercing pipe",form the diffusion impurity peak or channel,and the defect energy level and composite center.As a result,the ability became weak in conductive isolation layer in the intrinsic region of PIN finishing diode,the recombination generation current and the recombination center increased,which showed the correlation with the decline of electrical performance of the device.(4)The mechanism of carbon impurities in Czochralski(CZ)monocrystalline silicon in the electrical performance of PIN rectifier diode was studied.The bulk oxidation-induced stacking faults(B-OSF)in the intrinsic region of PIN rectifier diode was the reason that effected the electrical performance of the device.With the increase of carbon impurities content,the bulk oxidation-induced stacking faults(B-OSF)in the intrinsic region of PIN rectifier diode increased,and the effect of "impurity piercing pipe"increased,the electrical performance of PIN rectifier diode was reduced obviously.The defects mainly existed in the form of stacking fault and dislocation,and the stacking fault was the main form when the carbon content was greater than 6.10×1016at/cm3.The kinetic mechanism was analyzed when the substituted carbon CS captured the silicon self-interstitial silicon atoms SiI in the silicon matrix at high-temperature,the substituted carbon Cs would be transformed into interstitial carbon Ci,which would be formed a complex[Ci-Oi]with interstitial oxygen Oi in the silicon matrix,also known as carbon center.[Ci-Oi]would become the heterogeneous nucleation center of oxygen precipitation,which could continue to capture interstitial oxygen Oi,interstitial carbon Ci,self-interstitial silicon atoms SiI and other impurities,and promoted the compound body of[Ci-Oi-SiI]or oxygen precipitation.As carbon impurities participated in and promoted the generation and growth of oxygen precipitation.It was increased in the amount and volume significantly,which promoted the generation and growth of bulk oxidation-induced stacking faults(B-OSF).The existence of the bulk oxidation-induced stacking faults(B-OSF)could cause "impurity piercing effect",form the defect energy level and composite center.Therefore,the more serious the bulk oxidation-induced stacking faults(B-OSF),the more obvious the "impurity piercing pipe",and the more obvious decline of the electrical performance of PIN rectifier diode,the greater effect of carbon impurities on the electrical performance of PIN rectifier diode with the increase of initial carbon concentration.(5)Formation mechanism of bulk oxidation-induced stacking fault(B-OSF)in intrinsic region was studied.The bulk oxidation-induced stacking fault(B-OSF)in intrinsic region of the samples in oxygen content group and carbon content group were compared with pin rectifier diode diffused and not diffused.Combined with the preferential corrosion,FTIR and TEM tests,it was believed that the bulk oxidation-induced stacking fault(B-OSF)in the intrinsic region of pin rectifier diode increased obviously after the diffusion process of devices.The bulk oxidation-induced stacking fault(B-OSF)in the intrinsic region is formed by the aggregation and collapse of self-interstitial silicon atoms SiI at the stress of silicon matrix during the formation and growth of oxygen precipitation or[Ci-Oi-SiI].The bulk oxidation-induced stacking fault(B-OSF)in the intrinsic region is not formed at the oxygen precipitation or[Ci-Oi-SiI].(6)According to the first principle,the binding energy was calculated between oxygen,carbon and silicon atoms of oxygen-silicon binary system and carbon-oxygen-silicon ternary system in intrinsic region of PIN rectifier diode.The volumetric strain energy of dislocation and stacking fault under dislocation reaction mechanism was calculated,the theoretical calculation and analysis were carried out,which was basically consistent with the experimental characterization and test results.According to the particularity of PIN rectifier diode diffusion process,the experimental analysis and discussion of the bulk oxidationinduced stacking faults(B-OSF)formed by PIN rectifier diode diffusion process,the formation model were proposed respectively for the bulk oxidation-induced stacking faults(B-OSF)in intrinsic region under oxygen-silicon binary system and carbon-oxygen-silicon ternary system.It had reference significance for practical production and research. |
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