- Email: [email protected]
Selection of IR detectors for a fast laser soldering process with simultaneous solder joint qualification
454
World abstracts on microelectronics and reliability
SiC thin film was sputtered on a Si substrate at 600°C and annealed at 1300°C for 5 h in Ar atmosphere. For this MOSFET, the current-voltage characteristics of 1.6 and 0.6 #m channel length have been investigated. In this structure, the drain characteristics show an incomplete saturation because the channel depth is too wide to be depleted. For the other MOSFET, the SiC thin film is deposited at the sidewall of the SiOz insulator by RF sputtering at 600~C, and a 0.41am channel length has been developed. This M O S F E T shows good saturation characteristics. Also, this device possesses a drain breakdown voltage beyond 16 V. These experimental results give the foundation for the future development of submicron SiC power integrated circuit technology. Performance of thin-film chip resistors. LARRY BOS. IEEE Transactions on Components, Packaging, and Manufacturing Technology--Part A, 17, 3, 359 (September 1994). Increased use of thin-film surface mount chip resistors in military and high-performance industrial equipment has led to an increased awareness of potential failure modes in harsh environments. In this work, we have studied the behavior of chip resistors fabricated from tantalum nitride and nichrome metal films under biased humidity and have measured widely different results attributable to the metal film and protective system. The effects of electrostatic discharge (ESD) and high-temperature stability on these small resistive devices was also examined and related to the resistor design. Effect of inorganic binders on the properties of thick film copper conductor. Tosmo OGAWA et al., IEEE Transactions on Components, Packaging, and Manufacturing Technology Part A, 17, 4, 625 (December 1994). Adhesion strength and solderability of a copper thick film on alumina substrate were studied. Films were prepared with three kinds of inorganic binders, i.e., glass flits, mixture of glass flits and metal oxides, and metal oxides. The effects of inorganic binders on the adhesion and solderability were examined by analyzing physical and chemical behavior of the inorganic binders in the copper thick film during firing. The films with an addition of glass flit or mixtures of glass frit and metal oxide did not provide good adhesion and solderability simultaneously. However, the copper thick film containing 10wt°J~, bismuth oxide had excellent characteristics, i.e., high adhesion strength, good solderability, and low sheet resistivity. 9. ELECTRON, ION AND LASER BEAM TECHNIQUES Metal capping of MCM thin film features using a laser. R. S. PATEL,T. A. WASS1CKand C. Y. RALSTON.IEEE Transactions on Components, Packaging, and Manufacturing Technology--Part B, 17, 3, 264 (August 1994). A laser process to provide a thin barrier or
capping metal over the copper features of a multichip module thin film (MCM-D) structure is described. Capping of copper features is required to avoid copper corrosion and diffusion into overlaying dielectric layers of thin film structure. Furthermore, in a multi-level thin film structure, certain barrier metals provide improved adhesion for the subsequent dielectric layer. Experiments with XeCI and Nd-Yag lasers were performed to determine the best laser source for a copper/polymer/ceramic material set. The laser capping process is more robust and quicker than conventional photolithography or electroless plating capping processes, while eliminating the wet chemical operations. Also, the laser capping process eliminates the undercapping and variable capping metal thickness problems associated with photolithography and/or electroless plating techniques. The results of capping metal features on bare glass ceramic and polymer surfaces are described. Gold-to-gold TAB ILB with a laser. PHIL SPLETTER. IEEE Transactions on Components, Packaging, and Manufacturing Technology--Part B, 17, 4, 554 (November 1994). A new method for bonding gold plated TAB leads to gold bumps is presented. This method uses a frequency doubled N d : Y A G laser which provides energy in both the visible (0.533 lam) and near IR (1.064 ~tm) spectra. This combination of wavelengths overcomes the difficulty of bonding gold with only 1.064 ~tm radiation where 98% of the radiation is reflected. In the method presented in this paper, 0.5334tm radiation, of which 25-50% is absorbed by gold, is used to heat the gold which becomes more absorptive to the 1.0644tm radiation that is used to form the bond. Bonding experiments were conducted and samples were exposed to environmental testing. While there were initial bond failures, 85~o of the bonds did not degrade during environmental exposure indicating the potential for the process. Mass production of laser diodes by MBE. HIROSHI MATAKI and HARUO TANAKA. Microelectronics Journal, 25, 619 (1994). Molecular beam epitaxy (MBE) plays an important role in the mass production of A1GaAs laser diodes which have been widely used in a variety of opto-electronic applications. This paper provides an overview of self-aligned structure AIGaAs laser diodes fabricated by MBE ('SAM laser diodes') focusing on the GaAs passivation technique that we put into practical use for the first time, and on the modification of conventional MBE systems. Several features of SAM laser diodes for practical applications are also reviewed. Selection of IR detectors for a fast laser soldering process with simultaneous solder joint qualification. JOHANN NICOLICS, DIETER SCHROTTMAYER and LASZLO MUSIEJOVSKY. IEEE Transactions on Components, Packaging, and Manufacturing Technology-Part B, 17, 4, 596 (November 1994). High effort is
World abstracts on microelectronics and reliability
required for quality assurance after mass soldering of electronic devices. In contrast to that, a laser soldering process with an on-line quality control system is well-suited to the production of interconnections with high reliability. This contribution presents a new principle of closed loop control and a solder joint qualification method based directly on the recognition of wetting. In this way, shorter soldering cycles can be achieved compared to other systems. From thermal analysis of laser soldering processes it is known that wetting is related to a significant rise of the heat flow inside the solder joint leading to a characteristic change of the heat radiation which is detectable with an infrared detector. The selection of an infrared detector, the infrared measuring system and its application in a laser soldering system is described. The influences of thermal qualities of the solder joint and solder paste on the slope of the detector signal are discussed. The operating principle of the quality control algorithm is demonstrated at the soldering of 1812 and MELF0204 package components onto a 35-~m copper-plated printed wiring board (PWB).
Thin film bonding using ion beam techniques--a review. J. E. E. BAGLIN. I B M Journal of Research and Development, 38, 4, 413 (July 1994). Ion beam technologies provide a variety of well-proven means for creating or enhancing strong, stable, direct adhesion of thin films deposited on substrates. Interface chemical bonding and structure are critical. Yet success with such approaches has been reported for a great variety of systems that have little or no bulk chemical affinity, including metals, polymers, ceramics, and semiconductors. This review paper describes the established techniques of reactive and nonreactive ion beam sputtering, ion-beam-assisted deposition, ion implantation, and ion beam stitching. It then presents representative examples of adhesion enhancement selected from the current literature, in order to clarify the roles of interface chemistry, morphology, contaminants, and stability. The review offers a basis upon which interface tailoring for adhesion may be planned in order to optimize both performance and fabrication of specific materials systems.
Deposition of III-N thin films by molecular beam epitaxy. ROBERT F. DAVIS et al., Microelectronics Journal, 25, 661 (1994). Fabrication of optoelectronic devices from III N materials, operable in the blue and ultraviolet regions of the spectrum, has been a goal of many groups since the first infrared and red devices were commercially produced. Commercially viable blue-light-emitting diodes have now been achieved in these materials, and numerous investigators are now entering this field. Microelectronic devices are also of considerable interest. While much of the original research on GaN and InN centered around films with the wurtzite structure, the zincblende structure nitrides have
455
recently been receiving increasing interest because of their potential inherent advantages, e.g. increased carrier mobility. Recent results from several groups around the world have successfully addressed some of the traditional problems associated with growth of these materials. Chemical vapor deposition (CVD) has been a traditional growth technique for nitride growth and continues to be very successful. However, many researchers, including those growing III V nitrides, have turned to plasma-enhanced molecular beam epitaxy (MBE) for its important advantages in purity and in situ analytical capabilities. This paper reviews the recent developments in MBE growth of cubic boron nitride, aluminum nitride and the two poly-types of gallium nitride.
Recrystallization characteristics of polycrystalline silicon films amorphized by germanium ion implantation. MYEON-KOo KANG et al., Solid-State Electronics, 38, 2, 383 (1995). The recrystallization characteristics of polycrystalline silicon (poly-Si) films amorphized by germanium ion (Ge +) implantation on a SiO2 layer are studied by TEM analysis, and the possibility of enlarging the final grain size is investigated. Also, the characteristics of Ge + implanted films with phosphorus doping are reported and discussed. The nucleation and growth rates of undoped Ge + implanted films are lower and higher, respectively, than those of silicon ion (Si +) implanted films, so that the former films achieve grain sizes about 2 3 times larger than the latter films, depending on annealing temperature. Phosphorus doping in Ge + implanted films effectively enhances the grain size, because of the retardation of random nucleation and the enhancement of grain growth. An average grain size of 12ktm is obtained in doped Ge t implanted films with a phosphorus concentration of 1 × 102o ion/cm 3 after annealing at 650°C for 5 h, which is about four times larger than that in undoped Ge + implanted films.
Analysis of low energy boron implants in silicon through SiOz films: implantation damage and anomalous diffusion. L. KAABI, C. GONTRAND, B. REMAKI, F. SEIGNEUR a n d B. BALLAND. Microelectronics Journal, 25, 567 (1994). The experimental investigation reported in this paper focuses on the effect of induced implantation damage on the boron diffusion process. Boron is implanted at various fluences and energies in Cz-(100) silicon through different oxide layer thicknesses. Rapid thermal annealing (RTA) is used to activate shallow p+ layer (0.1-0.151am) following boron implantation. Concentrations versus depth boron profiles are measured using a secondary ion mass spectrometry (SIMS) analyser. An enhanced boron diffusion is detected in the tail region when the oxide thickness decreases. If the concentration peak is located at the oxide/silicon interface or in the substrate, further implantation damage is generated.
World abstracts on microelectronics and reliability
SiC thin film was sputtered on a Si substrate at 600°C and annealed at 1300°C for 5 h in Ar atmosphere. For this MOSFET, the current-voltage characteristics of 1.6 and 0.6 #m channel length have been investigated. In this structure, the drain characteristics show an incomplete saturation because the channel depth is too wide to be depleted. For the other MOSFET, the SiC thin film is deposited at the sidewall of the SiOz insulator by RF sputtering at 600~C, and a 0.41am channel length has been developed. This M O S F E T shows good saturation characteristics. Also, this device possesses a drain breakdown voltage beyond 16 V. These experimental results give the foundation for the future development of submicron SiC power integrated circuit technology. Performance of thin-film chip resistors. LARRY BOS. IEEE Transactions on Components, Packaging, and Manufacturing Technology--Part A, 17, 3, 359 (September 1994). Increased use of thin-film surface mount chip resistors in military and high-performance industrial equipment has led to an increased awareness of potential failure modes in harsh environments. In this work, we have studied the behavior of chip resistors fabricated from tantalum nitride and nichrome metal films under biased humidity and have measured widely different results attributable to the metal film and protective system. The effects of electrostatic discharge (ESD) and high-temperature stability on these small resistive devices was also examined and related to the resistor design. Effect of inorganic binders on the properties of thick film copper conductor. Tosmo OGAWA et al., IEEE Transactions on Components, Packaging, and Manufacturing Technology Part A, 17, 4, 625 (December 1994). Adhesion strength and solderability of a copper thick film on alumina substrate were studied. Films were prepared with three kinds of inorganic binders, i.e., glass flits, mixture of glass flits and metal oxides, and metal oxides. The effects of inorganic binders on the adhesion and solderability were examined by analyzing physical and chemical behavior of the inorganic binders in the copper thick film during firing. The films with an addition of glass flit or mixtures of glass frit and metal oxide did not provide good adhesion and solderability simultaneously. However, the copper thick film containing 10wt°J~, bismuth oxide had excellent characteristics, i.e., high adhesion strength, good solderability, and low sheet resistivity. 9. ELECTRON, ION AND LASER BEAM TECHNIQUES Metal capping of MCM thin film features using a laser. R. S. PATEL,T. A. WASS1CKand C. Y. RALSTON.IEEE Transactions on Components, Packaging, and Manufacturing Technology--Part B, 17, 3, 264 (August 1994). A laser process to provide a thin barrier or
capping metal over the copper features of a multichip module thin film (MCM-D) structure is described. Capping of copper features is required to avoid copper corrosion and diffusion into overlaying dielectric layers of thin film structure. Furthermore, in a multi-level thin film structure, certain barrier metals provide improved adhesion for the subsequent dielectric layer. Experiments with XeCI and Nd-Yag lasers were performed to determine the best laser source for a copper/polymer/ceramic material set. The laser capping process is more robust and quicker than conventional photolithography or electroless plating capping processes, while eliminating the wet chemical operations. Also, the laser capping process eliminates the undercapping and variable capping metal thickness problems associated with photolithography and/or electroless plating techniques. The results of capping metal features on bare glass ceramic and polymer surfaces are described. Gold-to-gold TAB ILB with a laser. PHIL SPLETTER. IEEE Transactions on Components, Packaging, and Manufacturing Technology--Part B, 17, 4, 554 (November 1994). A new method for bonding gold plated TAB leads to gold bumps is presented. This method uses a frequency doubled N d : Y A G laser which provides energy in both the visible (0.533 lam) and near IR (1.064 ~tm) spectra. This combination of wavelengths overcomes the difficulty of bonding gold with only 1.064 ~tm radiation where 98% of the radiation is reflected. In the method presented in this paper, 0.5334tm radiation, of which 25-50% is absorbed by gold, is used to heat the gold which becomes more absorptive to the 1.0644tm radiation that is used to form the bond. Bonding experiments were conducted and samples were exposed to environmental testing. While there were initial bond failures, 85~o of the bonds did not degrade during environmental exposure indicating the potential for the process. Mass production of laser diodes by MBE. HIROSHI MATAKI and HARUO TANAKA. Microelectronics Journal, 25, 619 (1994). Molecular beam epitaxy (MBE) plays an important role in the mass production of A1GaAs laser diodes which have been widely used in a variety of opto-electronic applications. This paper provides an overview of self-aligned structure AIGaAs laser diodes fabricated by MBE ('SAM laser diodes') focusing on the GaAs passivation technique that we put into practical use for the first time, and on the modification of conventional MBE systems. Several features of SAM laser diodes for practical applications are also reviewed. Selection of IR detectors for a fast laser soldering process with simultaneous solder joint qualification. JOHANN NICOLICS, DIETER SCHROTTMAYER and LASZLO MUSIEJOVSKY. IEEE Transactions on Components, Packaging, and Manufacturing Technology-Part B, 17, 4, 596 (November 1994). High effort is
World abstracts on microelectronics and reliability
required for quality assurance after mass soldering of electronic devices. In contrast to that, a laser soldering process with an on-line quality control system is well-suited to the production of interconnections with high reliability. This contribution presents a new principle of closed loop control and a solder joint qualification method based directly on the recognition of wetting. In this way, shorter soldering cycles can be achieved compared to other systems. From thermal analysis of laser soldering processes it is known that wetting is related to a significant rise of the heat flow inside the solder joint leading to a characteristic change of the heat radiation which is detectable with an infrared detector. The selection of an infrared detector, the infrared measuring system and its application in a laser soldering system is described. The influences of thermal qualities of the solder joint and solder paste on the slope of the detector signal are discussed. The operating principle of the quality control algorithm is demonstrated at the soldering of 1812 and MELF0204 package components onto a 35-~m copper-plated printed wiring board (PWB).
Thin film bonding using ion beam techniques--a review. J. E. E. BAGLIN. I B M Journal of Research and Development, 38, 4, 413 (July 1994). Ion beam technologies provide a variety of well-proven means for creating or enhancing strong, stable, direct adhesion of thin films deposited on substrates. Interface chemical bonding and structure are critical. Yet success with such approaches has been reported for a great variety of systems that have little or no bulk chemical affinity, including metals, polymers, ceramics, and semiconductors. This review paper describes the established techniques of reactive and nonreactive ion beam sputtering, ion-beam-assisted deposition, ion implantation, and ion beam stitching. It then presents representative examples of adhesion enhancement selected from the current literature, in order to clarify the roles of interface chemistry, morphology, contaminants, and stability. The review offers a basis upon which interface tailoring for adhesion may be planned in order to optimize both performance and fabrication of specific materials systems.
Deposition of III-N thin films by molecular beam epitaxy. ROBERT F. DAVIS et al., Microelectronics Journal, 25, 661 (1994). Fabrication of optoelectronic devices from III N materials, operable in the blue and ultraviolet regions of the spectrum, has been a goal of many groups since the first infrared and red devices were commercially produced. Commercially viable blue-light-emitting diodes have now been achieved in these materials, and numerous investigators are now entering this field. Microelectronic devices are also of considerable interest. While much of the original research on GaN and InN centered around films with the wurtzite structure, the zincblende structure nitrides have
455
recently been receiving increasing interest because of their potential inherent advantages, e.g. increased carrier mobility. Recent results from several groups around the world have successfully addressed some of the traditional problems associated with growth of these materials. Chemical vapor deposition (CVD) has been a traditional growth technique for nitride growth and continues to be very successful. However, many researchers, including those growing III V nitrides, have turned to plasma-enhanced molecular beam epitaxy (MBE) for its important advantages in purity and in situ analytical capabilities. This paper reviews the recent developments in MBE growth of cubic boron nitride, aluminum nitride and the two poly-types of gallium nitride.
Recrystallization characteristics of polycrystalline silicon films amorphized by germanium ion implantation. MYEON-KOo KANG et al., Solid-State Electronics, 38, 2, 383 (1995). The recrystallization characteristics of polycrystalline silicon (poly-Si) films amorphized by germanium ion (Ge +) implantation on a SiO2 layer are studied by TEM analysis, and the possibility of enlarging the final grain size is investigated. Also, the characteristics of Ge + implanted films with phosphorus doping are reported and discussed. The nucleation and growth rates of undoped Ge + implanted films are lower and higher, respectively, than those of silicon ion (Si +) implanted films, so that the former films achieve grain sizes about 2 3 times larger than the latter films, depending on annealing temperature. Phosphorus doping in Ge + implanted films effectively enhances the grain size, because of the retardation of random nucleation and the enhancement of grain growth. An average grain size of 12ktm is obtained in doped Ge t implanted films with a phosphorus concentration of 1 × 102o ion/cm 3 after annealing at 650°C for 5 h, which is about four times larger than that in undoped Ge + implanted films.
Analysis of low energy boron implants in silicon through SiOz films: implantation damage and anomalous diffusion. L. KAABI, C. GONTRAND, B. REMAKI, F. SEIGNEUR a n d B. BALLAND. Microelectronics Journal, 25, 567 (1994). The experimental investigation reported in this paper focuses on the effect of induced implantation damage on the boron diffusion process. Boron is implanted at various fluences and energies in Cz-(100) silicon through different oxide layer thicknesses. Rapid thermal annealing (RTA) is used to activate shallow p+ layer (0.1-0.151am) following boron implantation. Concentrations versus depth boron profiles are measured using a secondary ion mass spectrometry (SIMS) analyser. An enhanced boron diffusion is detected in the tail region when the oxide thickness decreases. If the concentration peak is located at the oxide/silicon interface or in the substrate, further implantation damage is generated.