- Email: [email protected]
Ion implanters: major 1986 trends
World Abstracts on Microelectronics and Reliability
391
substrate, this process tends to degrade the grating geometry by undercutting and by solution saturation effects. Ion beam milling and reactive ion plasma etching have proved effective in transferring photoresist patterns into the underlying solid substrate with reduced aberrations. Freon-14 (CF4) in a plasma has been utilized to etch gratings in soda-lime glass and lithium niobate (LiNbOs). Carbon tetrachloride (CC14) plasmas have similarly been used to transfer gratings into aluminium thin films on the substrate. The AI film pattern is then converted into an AI oxide mask by either milling in a 20~o 02/809/o Ar ion beam or by reactive ion etching in the presence of oxygen. The oxide acted as an in-contact mask with enhanced lifetime so that deeper gratings were transferred into the substrate by subsequent ion etching.
Ionized duster Imam technique. T. TAKAGI. Vacuum 36 (1-3), 27 (1986). Ionized cluster beams (ICB) are widely used to deposit metal, semiconductor and insulating films. This paper describes the current state of this technology in both fundamental and applications areas. ICB provides tight control of the kinetic energy and ion content of the beam, which gives the technique a unique advantage compared to MBE, VPE, LPE, MOCVD, sputtering or other thin film deposition methods. The development of this technology should allow the deposition of high quality material at low temperature onto a wide variety of substrate surfaces and even permit the formation of thin film materials not previously possible.
A self-focused multichannel electron Imam source for annealing of ion-implanted semiconductors. JuH-TZENG LUE,
CARL RUSSO,BJORN PEDERSENand DANIEL DOWNEY. Semiconductor int., 101 (April 1986). MeV ion implantation offers advantages over conventional technologies for some current and future device fabrication applications.
SHEAU-YANGSHYUand L[NG-HS/AOLYU. Vacuum 36 (5), 275 (1986). A field emission cathode composed of multiple tungsten pins providing uniform discharge and a Wehnelt cylinder performing focusing and triggering are the new features of this pulsed electron beam source. We have successfull annealed ion-implanted CdTe, Culn $2 and silicon from their damage states. The activation of p-type CdTe dopants can reach as high as 3 x l0 ta cm -3.
Imaging latch-up sites in CMOS integrated circuits using laser scanning. MARK H. WEICHOLD, DONALD L. PARKER and JEAN-FRANCOISFENECH. IEEE Trans. Compon. Hybrids mfg Technol. CHMT-8 (4), 556 (1985). A novel approach to using laser scanning to analyze latch-up sites in complementary metal-oxide semiconductor (CMOS) integrated circuits (IC's) has been developed. The technique employs a continuous wave (CW) laser beam scanned across a CMOS IC as the power to the IC is modulated. Signals corresponding to latch-up currents are detected with a lock-in amplifier and are used to produce a two-dimensional image of latch-up sites on a high resolution monitor.
Throughput
modeling for ion implantation. MICHAEL CURRENT and WES WEISENBERGER. Solid St. Technol., 79 (March 1986). Basic throughput parameters for ion implantation operations are described as a basis for equipmentspecific throughput calculations. In addition to considerations of idealized system performance in terms of wafer handling times, beam current and dose, key system considerations include the system availability, or uptime, and efficiency of operation, or utilization. The effects of "lab line politics" in the handling of small lot sizes per implant setup are shown to be a major factor in throughput performance. A basic model of waiting time for a multi-species process with a multi-system implant operation is described. An application for spreadsheet analysis is shown for an idealized machine performance model for eventual incorporation into a multisystem program.
Applications for MeV ion implantation. CHARLESMcKENNA,
Non-mass analysed ion implantation using microwave ion source. K. TOKIGUCH1,H. ITOH, N. SAKUDO,H. KOIKEand T. SAITOH. Vacuum 36(1-3), 11 (1986). To evaluate the usefulness of high-current non-mass analysed (NMA) ion implantation using a new microwave ion source, the photovoltaic properties of silicon solar ceils were studied. When phosphorus vapour is introduced into the ion source, it provides implant current of more than 10mA for the 5-15 keV energy range. The fraction of neutral phosphorus particles implanted together with ions is typically less than 10% of the total dose. The conversion efficiency of solar cells fabricated by NMA implantation is about 10% without any anti-reflection coating. Changes in implantation energy do not significantly change the values of these efficiencies. Continuous and stable oxygen ion beams of about l l 0 m A were obtained at 5.0kV, which is high enough to apply to material modification in metals, insulators and semiconductors.
Evaluating ion implanter options. DAVID CHURCH. Semiconductor int., 94 (April 1986). Several factors should be considered when selecting an ion implanter.
Laser planarization. DAVIDB. TUCKERMANand ANDREWH. WEISBERG. Solid St. Technol., 129 (April 1986). Many thin films (e.g. aluminum, gold, glass) can be planarized by momentarily melting them with optical pulses from a laser. Submicrosecond pulses are used in order to minimize the temperature rise in the substrate, reduce the energy required for melting, and prevent undesirable metallurgical reactions. This article describes recent work on laser planarization of thin metal films in multilevel IC metallization structures.
Ion implanters: major 1986 trends. PIETERBURGGRAAF.Semiconductor int., 78 (April 1986). Ion implanters continue to evolve to meet process needs with contamination control emphasized for production use.
A modified ion source for semiconductor implantation purposes. A. LATUSZYNS~, D. MACZKA and Yu. V.
Laser-based structure studies of silicon and gallium arsenide.
YUSHKIEVlCH and K. KISZCZAK. Vacuum 36(5), 263 (1986). The article describes an ion source that is a further improvement of the construction presented in A. Latuszyfiski, D. Maczka and Yu. V. Yushkievich, Proc. 4th Int. Conf. on Ion Implantation, Berchteseaden , 1982 (Edited by H. Ryssel and H. Glawischnig), p. 106, Springer, Berlin (1983). This modification of the design mainly consists of the reduction of the size of the discharge region. Its two goals included obtaining greater density of the plasma and increasing the source temperature. The latter factor allows ion losses in the ionization chamber to be decreased. Initial tests indicate that the changes introduced cause higher efficiency of the atom ionization process. In order to compare both new and old versions of the device, a brief review of source characteristics is also given.
GENTRY E. CROOK and BEN G. STREETMAN.1EEE Circuits Devices Mag., 25 (January 1986). Laser-based methods for silicon and gallium arsenide structure studies are nondestructible and capable of analyzing very small areas of a sample. These methods are used to monitor the effects of processing steps, determine the spatial uniformity of defects and doping across a wafer, and analyze devices. Two of the most widely used methods are photoluminescence measurements and Raman scattering. Photoluminescence measurements, used often in GaAs studies, collect radiation emitted from a sample irradiated with laser light of higher energy than the sample band-gap energy. This method identifies dopants and defects in the sample and assesses the relative amount of lattice damage caused by various processes. Raman scattering measurements collect laser radiation
391
substrate, this process tends to degrade the grating geometry by undercutting and by solution saturation effects. Ion beam milling and reactive ion plasma etching have proved effective in transferring photoresist patterns into the underlying solid substrate with reduced aberrations. Freon-14 (CF4) in a plasma has been utilized to etch gratings in soda-lime glass and lithium niobate (LiNbOs). Carbon tetrachloride (CC14) plasmas have similarly been used to transfer gratings into aluminium thin films on the substrate. The AI film pattern is then converted into an AI oxide mask by either milling in a 20~o 02/809/o Ar ion beam or by reactive ion etching in the presence of oxygen. The oxide acted as an in-contact mask with enhanced lifetime so that deeper gratings were transferred into the substrate by subsequent ion etching.
Ionized duster Imam technique. T. TAKAGI. Vacuum 36 (1-3), 27 (1986). Ionized cluster beams (ICB) are widely used to deposit metal, semiconductor and insulating films. This paper describes the current state of this technology in both fundamental and applications areas. ICB provides tight control of the kinetic energy and ion content of the beam, which gives the technique a unique advantage compared to MBE, VPE, LPE, MOCVD, sputtering or other thin film deposition methods. The development of this technology should allow the deposition of high quality material at low temperature onto a wide variety of substrate surfaces and even permit the formation of thin film materials not previously possible.
A self-focused multichannel electron Imam source for annealing of ion-implanted semiconductors. JuH-TZENG LUE,
CARL RUSSO,BJORN PEDERSENand DANIEL DOWNEY. Semiconductor int., 101 (April 1986). MeV ion implantation offers advantages over conventional technologies for some current and future device fabrication applications.
SHEAU-YANGSHYUand L[NG-HS/AOLYU. Vacuum 36 (5), 275 (1986). A field emission cathode composed of multiple tungsten pins providing uniform discharge and a Wehnelt cylinder performing focusing and triggering are the new features of this pulsed electron beam source. We have successfull annealed ion-implanted CdTe, Culn $2 and silicon from their damage states. The activation of p-type CdTe dopants can reach as high as 3 x l0 ta cm -3.
Imaging latch-up sites in CMOS integrated circuits using laser scanning. MARK H. WEICHOLD, DONALD L. PARKER and JEAN-FRANCOISFENECH. IEEE Trans. Compon. Hybrids mfg Technol. CHMT-8 (4), 556 (1985). A novel approach to using laser scanning to analyze latch-up sites in complementary metal-oxide semiconductor (CMOS) integrated circuits (IC's) has been developed. The technique employs a continuous wave (CW) laser beam scanned across a CMOS IC as the power to the IC is modulated. Signals corresponding to latch-up currents are detected with a lock-in amplifier and are used to produce a two-dimensional image of latch-up sites on a high resolution monitor.
Throughput
modeling for ion implantation. MICHAEL CURRENT and WES WEISENBERGER. Solid St. Technol., 79 (March 1986). Basic throughput parameters for ion implantation operations are described as a basis for equipmentspecific throughput calculations. In addition to considerations of idealized system performance in terms of wafer handling times, beam current and dose, key system considerations include the system availability, or uptime, and efficiency of operation, or utilization. The effects of "lab line politics" in the handling of small lot sizes per implant setup are shown to be a major factor in throughput performance. A basic model of waiting time for a multi-species process with a multi-system implant operation is described. An application for spreadsheet analysis is shown for an idealized machine performance model for eventual incorporation into a multisystem program.
Applications for MeV ion implantation. CHARLESMcKENNA,
Non-mass analysed ion implantation using microwave ion source. K. TOKIGUCH1,H. ITOH, N. SAKUDO,H. KOIKEand T. SAITOH. Vacuum 36(1-3), 11 (1986). To evaluate the usefulness of high-current non-mass analysed (NMA) ion implantation using a new microwave ion source, the photovoltaic properties of silicon solar ceils were studied. When phosphorus vapour is introduced into the ion source, it provides implant current of more than 10mA for the 5-15 keV energy range. The fraction of neutral phosphorus particles implanted together with ions is typically less than 10% of the total dose. The conversion efficiency of solar cells fabricated by NMA implantation is about 10% without any anti-reflection coating. Changes in implantation energy do not significantly change the values of these efficiencies. Continuous and stable oxygen ion beams of about l l 0 m A were obtained at 5.0kV, which is high enough to apply to material modification in metals, insulators and semiconductors.
Evaluating ion implanter options. DAVID CHURCH. Semiconductor int., 94 (April 1986). Several factors should be considered when selecting an ion implanter.
Laser planarization. DAVIDB. TUCKERMANand ANDREWH. WEISBERG. Solid St. Technol., 129 (April 1986). Many thin films (e.g. aluminum, gold, glass) can be planarized by momentarily melting them with optical pulses from a laser. Submicrosecond pulses are used in order to minimize the temperature rise in the substrate, reduce the energy required for melting, and prevent undesirable metallurgical reactions. This article describes recent work on laser planarization of thin metal films in multilevel IC metallization structures.
Ion implanters: major 1986 trends. PIETERBURGGRAAF.Semiconductor int., 78 (April 1986). Ion implanters continue to evolve to meet process needs with contamination control emphasized for production use.
A modified ion source for semiconductor implantation purposes. A. LATUSZYNS~, D. MACZKA and Yu. V.
Laser-based structure studies of silicon and gallium arsenide.
YUSHKIEVlCH and K. KISZCZAK. Vacuum 36(5), 263 (1986). The article describes an ion source that is a further improvement of the construction presented in A. Latuszyfiski, D. Maczka and Yu. V. Yushkievich, Proc. 4th Int. Conf. on Ion Implantation, Berchteseaden , 1982 (Edited by H. Ryssel and H. Glawischnig), p. 106, Springer, Berlin (1983). This modification of the design mainly consists of the reduction of the size of the discharge region. Its two goals included obtaining greater density of the plasma and increasing the source temperature. The latter factor allows ion losses in the ionization chamber to be decreased. Initial tests indicate that the changes introduced cause higher efficiency of the atom ionization process. In order to compare both new and old versions of the device, a brief review of source characteristics is also given.
GENTRY E. CROOK and BEN G. STREETMAN.1EEE Circuits Devices Mag., 25 (January 1986). Laser-based methods for silicon and gallium arsenide structure studies are nondestructible and capable of analyzing very small areas of a sample. These methods are used to monitor the effects of processing steps, determine the spatial uniformity of defects and doping across a wafer, and analyze devices. Two of the most widely used methods are photoluminescence measurements and Raman scattering. Photoluminescence measurements, used often in GaAs studies, collect radiation emitted from a sample irradiated with laser light of higher energy than the sample band-gap energy. This method identifies dopants and defects in the sample and assesses the relative amount of lattice damage caused by various processes. Raman scattering measurements collect laser radiation