EFFECT OF PASSIVATING COATINGS ON METALLIZATION TOPOLOGY IN PRODUCTION OF SEMICONDUCTOR DEVICES

The surface quality of the metallized contact pads on the crystal plays an important role in the production of semiconductor devices. This paper presents experimental studies of the effect of a protective passivation film of silicon oxide on the surface structure of aluminum metallization in the field of forming contact pads. Plasma chemical deposition of passivation layer SiO2 from gas phase (PECVD method) was carried out on prepared samples of silicon with aluminum metallization using a high-frequency power source with a frequency of 13.56 MHz. After that, chemical etching of precipitated silicon oxide was carried out to simulate the process of forming contact areas of semiconductor device crystals. The resistance of the metallization surface to plasma processes was studied by raster electron microscopy. It is shown that as a result of the process cycle, defects of the dislocation type are generated in the applied film Al. The nature of the observed defects has been found to be different. The revealed large square-shaped pits with a size of ~ 1 μm at the places where dislocations come to the surface are of a single nature and appear independently of the processes of applying passivation coatings, which is determined by the orienting action of a single-crystal substrate having some low dislocation density. While the second type of defects, shown by the presence of etching pits measuring ~ 100-300 nm, is characterized by a higher surface density. Moreover, the exclusion of the passivation process with silicon oxide did not lead to the appearance of this type of defects, which determined their nature associated with the ion bombardment of the Al layer during the plasma chemical deposition of silicon oxide from the gas phase. It is also shown that a feature of this type of defects is their disorientation both with respect to the first type of defects and with respect to each other. Detection of the structure of the metallization layers was carried out by X-ray diffraction, the results of which show the polycrystallinity of the formed aluminum metallization. The preferred orientation of the aluminum film corresponds to the substrate Si (111).

Verification of a Fabless Device Model Using TCAD Tools: from Bipolar Transistor Formation to I-V Characteristics Extraction

This paper describes the analysis of processes used in microand nanoelectronic device manufacturing. It also presents an exemplary and novel laboratory exercise in which an epitaxial planar n + pn bipolar transistor with junction isolation is illustrated and analyzed stepbystep. Only seven photolithography steps are used to obtain this bipolar transistor structure: for buried layer formation, for junction transistor isolation and collectors regions formation, for base region formation, for emitter and collector n+ region formation, for contact windows, for first aluminum metallization, and, finally, for passivation. Silvaco TCAD software tools are used to implement all of these manufacturing processes and to simulate the resulting IV characteristics of all presented semiconductor structures. This type of laboratory work provides students with basic knowledge and a consistent understanding of bipolar transistor manufacturing, as well as facilitating theoretical understanding, analysis, and simulation of various semiconductor manufacturing processes without the need for costly and lengthy technological manufacturing experiments. This article also presents the conclusions and other benefits of such laboratory work, as well as possible recommendations for further improvement or expansion.

THE EFFECT OF THIN DIELECTRIC LAYERS AT SILICON ON INTERCONNECTION HEATING DYNAMICS AT THERMAL SHOCKS

The relevance of the study is due to the fact that in the conditions of development of micro-and nanoelectronics, it is necessary to pay attention to resistive switching systems, which are the basis in the structures of these areas of electronics. The work deals with the investigation of the role of thin dielectric layers of silicon oxide and nitride on interconnection heating dynamics at monocrystalline silicon plates. The leading method to the study of this problem is the method of experiment, which allows identifying the features of the influence of the dielectric sublayer on the thermal regimes of multilayer systems. It is shown that passage of current pulses (amplitude up to 6x1010 A/m² and duration up to 600 μs) leads to thermal damage of interconnections right up to breaking the electric circuit. The character of destruction strongly depends on the quality of deposition of dielectric and metal films as well as on the state of the dielectric-metal interface. It was found that the oscillograms of the inclusion, taken during the passage of a current pulse, clearly reflect the change in the dimensional (h2) and thermal (λ2) parameters of the dielectric sublayers; considered the thermal degradation mechanisms of the aluminum metallization systems with thin dielectric sublayers related to its melting; it was found that formation of melted zones is related to local reduction of film cross-section and consequently to the appearance of a melted zone that coagulates into drops in the course of current pulse passing and promotes breaking the electric circuit. The proposed method can be applied to assess the thermal properties of thin films of dielectrics.

H3TRB Test on 650 V SiC JBS Diodes

Reliability characterization of SiC devices is an ongoing activity. For this work, 650 V SiC JBS diodes in TO247 housings were tested in H3TRB. After a test period of 4000 hours none of the devices had failed during the test and only two out of sixteen devices had failed during blocking curve measurements performed at intermediate time steps. This is significantly better performance than many silicon devices offer today. The failure spots of the failed devices were detected at the edge of the main junction appearing as semi-circular cavities in the aluminum metallization. All other devices did not even show deviations from their original blocking curves.