Lithography is a field in which advances proceed at a swift pace. This book was written to address several needs, and the revisions for the second edition were made with those original objectives in mind. Many new topics have been included in this text commensurate with the progress that has taken place during the past few years, and several subjects are discussed in more detail. This book is intended to serve as an introduction to the science of microlithography for people who are unfamiliar with the subject. Topics directly related to the tools used to manufacture integrated circuits are addressed in depth, including such topics as overlay, the stages of exposure, tools, and light sources. This text also contains numerous references for students who want to investigate particular topics in more detail, and they provide the experienced lithographer with lists of references by topic as well. It is expected that the reader of this book will have a foundation in basic physics and chemistry. No topics will require knowledge of mathematics beyond elementary calculus.

Principles of Lithography

Effect of bleaching on restorative materials and restorations—a systematic review

Nanofabrication is playing an ever increasing role in science and technology on the nanometer scale and will soon allow us to build systems of the same complexity as found in nature. Conventional methods that emerged from microelectronics are now used for the fabrication of structures for integrated circuits, microelectro-mechanical systems, microoptics and microanalytical devices. Nonconventional or alternative approaches have changed the way we pattern very fine structures and have brought about a new appreciation of simple and low-cost techniques. We present an overview of some of these methods, paying particular attention to those which enable large-scale production of lithographic patterns. We preface the review with a brief primer on lithography and pattern transfer concepts. After reviewing the various patterning techniques, we discuss some recent application issues in the fields of microelectronics, optoelectronics, magnetism as well as in biology and biochemistry.

Nanofabrication: conventional and nonconventional methods.

A lithographic projection apparatus includes a liquid confinement structure extending along at least a part of a boundary of a space between a projection system and a substrate table. The liquid confinement structure is positioned adjacent a final surface of the projection system and includes a first inlet configured to supply a liquid, through which a patterned beam is to be projected, to the space, and a second inlet configured to supply gas and formed in a face of the structure. The face is arranged to oppose a surface of the substrate and the second inlet is located radially outward, with respect to an optical axis of the projection system, of the space and has a porous member to evenly distribute gas flow over an area of the second inlet.

Lithographic Projection Apparatus

An inspection apparatus and a semiconductor device manufacturing method using the same. The inspection apparatus is used for defect inspection, line width measurement, surface potential measurement or the like of a sample such as a wafer. In the inspection apparatus, a plurality of charged particles is delivered from a primary optical system to the sample, and secondary charged particles emitted from the sample are separated from the primary optical system and introduced through a secondary optical system to a detector. Irradiation of the charged particles is conducted while moving the sample. Irradiation spots of the charged particles are arranged by N rows along a moving direction of the sample and by M columns along a direction perpendicular thereto. Every row of the irradiation spots of the charged particles is shifted successively by a predetermined amount in a direction perpendicular to the moving direction of the sample.

Inspection system by charged particle beam and method of manufacturing devices using the system

Projection reduction exposure with variable axis immersion lenses (PREVAIL) represents the high throughput e-beam projection approach to NGL, which IBM is pursuing in cooperation with Nikon as alliance partner; another e-beam projection approach is SCALPEL pursued by Lucent Technologies. This article discusses the challenges and accomplishments of the PREVAIL project. It will focus on the results obtained with the proof of concept (POC) system. This system was developed to demonstrate key technical building blocks required for high throughput, high resolution e-beam step, and scan projection lithography. The supreme challenge facing all e-beam lithography approaches has been and still is throughput. Since the throughput of e-beam projection systems is severely limited by the available optical field size, the key to success is the ability to overcome this limitation. The PREVAIL technique overcomes field-limiting off-axis aberrations through the use of variable axis lenses, which electronically shift the o...

Projection reduction exposure with variable axis immersion lenses: Next generation lithography

This invention provides the charged particle beam transfer method, which can control adverse effect of distortion or blur that arises from the space charge effect due to the non-uniform pattern density to a minimum. A pattern formed on reticle is raster or step-and-repeat scanned with a charged particle beam and is illuminated in consecutive order, and a pattern image of a sub-field, which is illuminated, is to be formed on a certain position of a radiation sensitive substrate. On the radiation sensitive substrate whole pattern is projected through stitching the said pattern image. The pattern is to be divided into plural areas A and B which differ in pattern density one another, and the above-described scan boundary is made to coincide with the boundary of these plural areas.

Charged particle beam transfer method

Electron-beam projection-exposure apparatus are disclosed that allow a mask pattern to be transferred to a sensitized substrate without defects. An apparatus includes an electron-beam scanner, housed in a vacuum chamber, that scans an electron beam over the mask. As the mask is scanned, an emitted-electron detector senses electrons emitted from the mask at a point of contamination. The contamination is then removed from the mask by a mask-cleaning system, after which the mask is used for exposing a sensitized substrate. The scanner as well as the mask-cleaning system are housed in the same vacuum chamber where projection-exposure of the substrate are performed. Thus, the mask is not exposed to the external environment during inspection, cleaning, and projection-exposure, and inspection, cleaning and projection-exposure of the mask are performed more rapidly than conventionally. The mask-cleaning system, which can utilize a laser beam or a locally delivered reactive gas, cleans the mask at only the points of contamination, rather than the entire mask. Thus, cleaning time is shortened.

Electron-beam-projection-exposure apparatus with integrated mask inspection and cleaning portions

The spatial coherence and the beam divergence at 248 nm of a KrF excimer laser were obtained experimentally. These results are in good agreement with the theoretical calculations based on a simple pulse-laser model and the van Cittert-Zernike theorem. The relation between the spatial coherence and the beam divergence was obtained theoretically and supported by experimental results. This expression is given as a function of the wavelength of the laser but includes no parameters related to the laser structure. It is shown that these theoretical results are applicable to various kinds of pulse laser.

Spatial coherence of KrF excimer lasers

The imaging concept of electron projection lithography (EPL) with silicon stencil reticle is explained. A silicon membrane thickness of 1 - 4 micrometer is suitable for the reticle. A scattering contrast of greater than 99% is expected. Nikon EB stepper's dynamic writing strategy of discrete exposure on a sub-field by sub-field basis with deflection control of the electron beam is explained. The basic system configuration of EB stepper is introduced. Examples of error budget for CD variation and Overlay/Stitching are shown. Nikon's policy for countermeasures for critical issues such as proximity effect correction, sub-field/complementary stitching and wafer heating influence are explained. For extensibility down to 70 nm and below, both exposure tool and reticle should be improved.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Shintaro Kawata

Papers

Projection reduction exposure with variable axis immersion lenses: Next generation lithography

Charged particle beam transfer method

Electron-beam-projection-exposure apparatus with integrated mask inspection and cleaning portions

Spatial coherence of KrF excimer lasers

Nikon EB stepper: its system concept and countermeasures for critical issues