Pellicle mask protection for 1: 1 projection lithography

World Abstracts on Microelectronics and Reliability Multilayer resist systems and processing. B. J. LIN. Solid St. TechnoL, 105 (May 1983). Utilizing a thick planarizing layer at the bottom and a thin imaging layer on top, multilayer resist systems offer improvements in sensitivity, linewidth control, height-to-width aspect ratio of the resist image, manipulation of the resist image profile, focus tolerance, proximity effects, and charging effects, in optical, e-beam X-ray, and ion-beam lithography. The particular improvements related to each imaging means are discussed and illustrated in this paper, showing that with all known imaging means, multilayer resist systems can indeed improve lithographic performance. Design of plasma deposition reactors. WAYNE L. JOHNSON. Solid St. Technol., 191 (April 1983). Plasma-enhanced CVD is the most promising technology for low temperature deposition of a wide variety of materials. The activation, discharge and deposition physics control the performance of the process. The deposition systems are a compromise between competing engineering and physics constraints, in order to provide the best composite of particulate generation, uniformity, stress and throughput considerations. Sources of semiconductor wafer contamination. JOHN A. LANGE. Semiconductor Int., 124 (April 1983). A primary source of contamination in wafer production lies within human skin. Positive-resist processing considerations for VLSI lithography. L. K. WHITE and D. MEYERHOFER.RCA Rev. 44, 110 (1983). The resolution and packing density requirements for VLSI manufacture present new processing considerations for positive-resist optical lithography. More attention to the processing details are required as well as better control of processing conditions. The more violent dry etching techniques and high energy implants place new demands on the positive-resist masking properties. Topographical features make dimensional control more difficult and severely narrow the latitude of the positive resist process. Resist thickness variations, reflections off sidewalls, and standing-wave phenomena are responsible for the diminished process latitude. High quality aerial images enhance process latitude. Preserving the quality of the resist image reduces dimensional deviations on topographical features. Computer modelling of positive resist exposure and development provides useful information for accessing the effects of several processing parameters. Estimating orthogonality deviation of a step-and-repeat lithographic system. L. C. HStA and L. S. St;. Solid St. Technol., 155 (May 1983). Orthogonality variation is one of the major overlay components in mask registration. It is caused by the nonperpendicularity of the stage axes of a step-and-repeat system. Advanced measuring tools and techniques have made it possible to measure and understand misregistration caused by orthogonality variation. In this paper four different methods for estimating orthogonality variation are discussed. These methods are direct and sensitive and so do not involve electrical test structures. They are being used in mask production monitoring efforts. Superclean chemicals: a status report. RON ISCOFF. Semiconductor Int., 88 (April 1983). Ultra-low particulate/high purity chemicals--etchants, solvents, strippers and photoresists--have been commercially available for nearly five years. Acceptance, however, has been slow. Plasma processing--an art or a science? ADIR JACOB.Solid St. Technol., 151 (April 1983). The non-quantitative nature of investigations related to plasma technology as applied to the manufacture of semiconductor devices is highlighted. Examples are taken from fundamental processes related to electron impact-induced dissociation of common gaseous

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plasma etchants employed during integrated circuit patterning. A few of the related phenomenological difficulties are discussed, and recourse is made to a potentially fruitful industry-university technical interaction. Photoresist technology update. AARON D. WEISS. Semiconductor Int., 82 (April 1983). Negative photoresists still predominate but as geometries shrink positive photoresists are gaining ground. E-beam resists for direct write and X-ray resists are still in the future. A suspended boat loader based on the cantilever principle. J. L. LAMBERT and C. J. BAYNE. Semiconductor Int., 150 (April 1983). The loading and unloading of furnace process tubes has proven to be a major source of quartz particulate contamination. It is evident that a new alternative to standard loading procedures must be considered. Pellicle mask protection for 1 : 1 projection lithography. T. A. BRUNNER, C. P. AUSSCHNITT and D. L. DULY. Solid St. Technol., 135 (May 1983). The physical properties of pellicles most relevant to their use as mask protectors are discussed. Ultraviolet transmission spectra are presented and related to the photodegradation which limits the useful lifetime of pellicles. Optical thickness maps, based on Phase Measuring Interferometry (PMI), reveal the high quality of current pellicle fabrication techniques. The effect of pellicles on lithographic performance is reported, as measured by electrically probeable test structures. Results are presented pertaining to the impact of pellicles on the linewidth control, aerial image acuity, contrast and defect density obtainable on 1 : 1 projection printers. Centrifugal on-center, flood-spray developing of positive photoresist. DON BURKMAN and ARDELLE JOHNSON. Solid St. Technol., 125 (May 1983). The centrifugal, on-centre, floodspray, concept used in a positive photoresist developing system is detailed. Data pertinent to positive developing for LSI and VLSI integrated circuits are presented. Topics discussed include optimization of parameters, resolution, sidewall profiles, uniformity, film thickness loss, latitude and differential solubility. Mix-and-match alignment: cost effective for VLSI. PIETERS. BURGGRAAF. Semiconductor Int., 59 (April 1983). Mix-andmatch alignment can be both economical and expedient when it extends the production use of existing aligners while advanced systems are added to a wafer-fabrication line as needed. CAD system coordinates complete semicustom chip design. A. FELLER, R. NOTO, D. C. SMITH, B. S. WAGNER and R. PUTATUNDA, Electronics, 116 (16 June 1983). Data management organizes design software and checks user inputs; secure file stores proprietary data; expanded system will handle VLSI. Dynamic element matching puts trimless converters on chip. RUDY VAN DE PLASSCHE. Electronics, 130 (16 June 1983). Analog-to-digital and digital-to-analog converters for audio systems reach 14 bits without trimming. Application of automatic alignment to MOS processing in projection printing. DAN BERRY, PENNY KERN and HARRY SEWELL. Solid St. Technol., 87 (May 1983). Implementing automatic mask-to-wafer alignment during the photolithographic phase of IC fabrication can be a frustrating and time consuming experience without an understanding of the basic phenomena involved. The very nature of the complex physical processes involved causes the type and quality of optical images on the wafer targets to be difficult to predict. Fabrication of state-of-the-art circuits requires a high degree of alignment precision often approaching accuracies ten times