摘要:

The aberration of electrostatic lens and deflection systems due to misalignment is analyzed for design of microfabrication systems. The potential for a lens and deflector having an electrode axis shift is approximated by introducing a shift function that expresses the electrode shift from the optical axis. On the basis of this approximation, mixed aberrations due to misalignment of lens and deflector electrodes can be analyzed, including the effect of a nonuniform electrode axis shift. Practical third order aberration coefficients are formulated in a compact form by eight integration functions, and are classified into 67 geometrical aberration coefficients and 4 chromatic aberration coefficients.

ISSN:0734-211X    

DOI:10.1116/1.585043

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The measurement error induced by the intensity distribution in the reflected beam from the surface of a substrate was studied to improve the focal accuracy of an autofocus system. It is shown that scanning of the probe beam across the wafer surface reduces the effect of nonuniform reflectivity. An accuracy of 0.6 μm can be obtained. A signal processing circuit which accommodates 40 dB of incident intensity range is developed.

ISSN:0734-211X    

DOI:10.1116/1.585044

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

In this paper the interaction between a trimethylsilylated silicon substrate and diazonaphthoquinone–novolak photoresist material has been examined. Time‐of‐flight secondary ion mass spectrometry (TOF SIMS) and contact angle measurements of water have been used to determine the surface coverage of trimethylsiloxy (TMS) groups on cleaned and subsequently treated silicon wafers. A linear relation is obtained between the relative surface coverage as measured by TOF SIMS and the cosine value of the contact angle. The surface coverage of the TMS groups has to exceed a value of about 50% of a monomolecular layer to assure the absence of lift‐off of photoresist. Contrary to the common belief that trimethylsilylation of silicon substrates improves the adhesion between photoresist and the silicon substrate, it rather deteriorates the adhesion. This is further corroborated by experiments on silica particles. It is proposed that the low‐surface energy of the trimethylsilylated surface prevents the penetration of the alkaline developer solution into the interface of the silicon substrate and the photoresist material.

ISSN:0734-211X    

DOI:10.1116/1.585045

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Submicron features have been fabricated in silicon dioxide and chromium using cadmium fluoride (CdF2) in a lift‐off mask scheme. High‐resolution lines are patterned by the electron beam on PMMA on a SiO2substrate and a thin film of CdF2is then evaporated. Following a lift‐off stage in chloroform, a pattern reversal of the PMMA image is obtained in CdF2, which is then etched in the RIE mode, providing a high selectivity with SiO2(>30) and giving a highly anisotropic etch in SiO2. In this way, high‐resolution submicron features in silicon dioxide with dimensions of 0.4 μm (wide) and 1 μm (deep) have been obtained. A similar procedure was used for chromium on glass.

ISSN:0734-211X    

DOI:10.1116/1.585046

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The influence of28Si+ion implantation on the interfacial chemistry and adhesion of 30 nm Ni films on po1y[N,N‐(p,p’‐oxydiphenylene) pyromellitimide] (PI) substrates was examined. The Ni/PI specimens were held at temperatures below 100 °C, and implanted with 55 keV28Si+at doses of either 1×1016, 5×1016or 1×1017Si/cm2. The 1×1016Si/cm2implants had no influence on the surface topography, but the higher dose implants introduced some submicron void formation. Cross‐sectional transmission electron microscopy and Auger electron spectroscopy depth profile analyses showed that the as‐deposited Ni films formed very sharp interfaces with the polyimide substrates. However, after implantation the interfaces became graded by up to a factor of 2 compared to the as‐deposited specimens. Large quantities of C were transferred into the Ni films, resulting in the formation of a C overlayer. The concentration of implanted Si reached a maximum (at approximately 16 at. % for the 1×1017Si/cm2implant) in the Ni films and extended deeply into the PI substrates. X‐ray photoelectron spectroscopy analysis of the interfaces of the specimens implanted with 1×1017Si/cm2showed a mixture of Ni–Si, Si–O, and C–O chemical bonding, consistent with Ni–Si–O–C complex formation. Adhesion testing showed substantial adhesion increases (up to a factor of 20) with28Si+dose. The Ni films implanted with 1×1017Si/cm2were only removed upon substrate failure. The adhesion increases induced by28Si+implantation are attributed to a combination of substrate toughening, mechanical interlocking, interfacial grading, and chemical bonding across the interfaces.

ISSN:0734-211X    

DOI:10.1116/1.585047

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The influence of84Kr+ion implantation on the interfacial chemistry and adhesion of 30 nm Ni films on poly[N,N‐(p,p’‐oxydiphenylene) pyromellitimide] polyimide (PI) substrates was examined. The Ni/PI specimens were held at temperatures below 100°C and implanted with 170 keV84Kr+at doses of either 5×1015, 1×1016, or 5×1016Kr/cm2. At low doses, the topography of the specimens remained smooth. However, after implantation with 5×1016Kr/cm2, the Ni films were largely destroyed by island formation. The as‐deposited films formed sharp interfaces with the PI substrates. After implantation, the interfaces remain sharp, but large quantities of C had been transferred from the PI substrates into the Ni films. An average film stoichiometry of approximately nickel carbide (Ni3C) resulted after both the 5×1015and the 1×1016Kr/cm2implants. X‐ray photoelectron spectroscopy analyses showed (Ni3C) formation at the interfaces of both the as‐deposited and ion implanted Ni/Pl specimens. Although the Ni3C formation extended more deeply into the ion implanted Ni films, the chemical bonding at the Ni/PI interfaces was not greatly affected by the ion implantation. Adhesion evaluations, performed using a scratch test in conjunction with scanning electron microscopy and Auger electron spectroscopy analysis, showed an adhesion enhancement of greater than a factor of 3 for the specimens implanted with either 5×1015or 1×1016Kr/cm2. This adhesion enhancement was attributed primarily to the mechanical interlocking (interfacial mixing) of the Ni films and the PI substrates. While this adhesion enhancement is significant, it is much less than the factor of 20 enhancement previously observed after28Si+implantation.

ISSN:0734-211X    

DOI:10.1116/1.585048

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The influence of 10 nm Si intermediate layers and84Kr+implantation on the adhesion of 30 nm Ni films on poly [N,N‐(p,p’‐oxydiphenylene) pyromellitimide] (PI) substrates was examined. The Ni/Si/PI specimens were implanted with either 5×1015, 1×1016, or 5×1016Kr/cm2at a specimen temperature of less than 100 °C. Surface topography remained smooth after the 5×1015and 1×1016Kr/cm2implants. In contrast, the 5×1016Kr/cm2implant resulted in extensive island formation, which destroyed the integrity of the Ni films. Auger electron spectroscopy (AES) depth profiles of the as‐deposited films showed graded Ni distributions throughout the Si intermediate layers, which form abrupt interfaces with the PI substrates. After implantation with 5×1015or 1×1016Kr/cm2implants, the Si intermediate layers become highly oxidized. Significant quantities (15 to 20 at. % in the Ni film) of carbon were transferred into the Ni films from the PI substrates, but the interface to the PI substrates remained sharp. The Ni that was present in the as‐deposited Si layers appears to segregate out of these layers after the ion‐induced oxidation. X‐ray photoelectron spectroscopy (XPS) analysis showed that the chemistry of the Si interfacial layers changed from a mixture of SiO and Ni2Si in the as‐deposited specimens to almost entirely SiO2in the implanted specimens. The adhesion of the Ni films was examined using a scratch test. The as‐deposited Ni films were removed at a force of 4 N with failure at the Si/PI interface. After ion implantation, the films were removed at a force of only 2 N, and the failure occurred at the Ni/SiO2interface. This reduction in adhesion, which was in startling contrast to the adhesion enhancement obtained by implanting Ni/PI specimens with28Si+, was attributed to the preferential formation of SiO2during the84Kr+ion bombardment. It was concluded that the Si must be implanted into both the Ni films and the PI (or other oxygenated polymers) in order to maximize the adhesion enhancement of Ni films.

ISSN:0734-211X    

DOI:10.1116/1.585049

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Stress‐induced migration is investigated based on direct measurements of average stress in aluminum fine lines. Measured lifetime of the lines is expressed as a power function of the longitudinal tensile stress. The stresses in the fine lines are not directly influenced by the internal stress of the passivation layers, but are caused mainly by thermal expansion mismatch.

ISSN:0734-211X    

DOI:10.1116/1.585050

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The influence of some important process parameters on the quality of electrical contacts to a silicon substrate has been studied for a double‐level metallization system consisting of Al–MoSi2–Al(Cu,Si)–cSi. This double‐level metallization scheme is presently used in the production of advanced complementary metal–oxide semiconductor devices. The metal films were produced in two commercially available sputtering systems. A detailed picture of the reactions within the metal films and at the interface to the substrate was obtained by means of Rutherford backscattering spectroscopy, secondary ion mass spectroscopy, x‐ray diffraction (diffractometer and Read camera), differential scanning calorimetry, metallographic sectioning, and scanning electron microscopy, in addition to electrical measurements on contact chains and Kelvin contact structures. The dependence of the stoichiometry of the deposited MoSi2film on the sputtering pressure was determined in the range 1–15 mTorr. The formation of hexagonal MoSi2from the amorphous as‐deposited film was found to occur around 380 °C with an activation energy of 1.9 eV and an enthalpy of crystallization of about 40 kJ/mol. These results are shown to be compatible with theoretical estimates. Depending on the particular conditions during the deposition of the MoSi2film, Si was found to be taken up or rejected during anneals up to 425 °C. This led to spiking and precipitation, respectively. Diffusion of Mo into the Al films is shown to have resulted in the formation of MoAl12. The contacts were found to be stable during at least 70 min for temperatures up to 450 °C. It is shown that by proper tailoring of the sputtering conditions and a judicious choice of time and temperature for the postanneal cycle, it is possible to avoid the problems of spiking and silicon precipitation inherent in a metallization system based on a combination of aluminum with a near‐stoichiometric silicide.

ISSN:0734-211X    

DOI:10.1116/1.585051

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

An ultrahigh vacuum chemical vapor deposition system suitable for deposition of epitaxial GexSi1−xhas been constructed. We report details of its construction and operation and demonstrate deposition of epitaxial silicon and GexSi1−xat temperatures as low as 577 °C. Measurements of thickness uniformity both across and between wafers are also presented.

ISSN:0734-211X    

DOI:10.1116/1.585052

出版商:American Vacuum Society    

年代:1990

数据来源: AIP