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

The present invention provides a reliable, high-repetition rate, production line compatible high energy photon source. A very hot plasma containing an active material is produced in vacuum chamber. The active material is an atomic element having an emission line within a desired extreme ultraviolet (EUV) range. A pulse power source comprising a charging capacitor and a magnetic compression circuit comprising a pulse transformer, provides electrical pulses having sufficient energy and electrical potential sufficient to produce the EUV light at an intermediate focus at rates in excess of 5 Watts. In preferred embodiments designed by Applicants in-band, EUV light energy at the intermediate focus is 45 Watts extendable to 105.8 Watts.

Extreme ultraviolet light source

An energy-efficient method and system for processing target material such as microstructures in a microscopic region without causing undesirable changes in electrical and/or physical characteristics of material surrounding the target material is provided. The system includes a controller for generating a processing control signal and a signal generator for generating a modulated drive waveform based on the processing control signal. The waveform has a sub-nanosecond rise time. The system also includes a gain-switched, pulsed semiconductor seed laser for generating a laser pulse train at a repetition rate. The drive waveform pumps the laser so that each pulse of the pulse train has a predetermined shape. Further, the system includes a laser amplifier for optically amplifying the pulse train to obtain an amplified pulse train without significantly changing the predetermined shape of the pulses. The amplified pulses have little distortion and have substantially the same relative temporal power distribution as the original pulse train from the laser. Each of the amplified pulses has a substantially square temporal power density distribution, a sharp rise time, a pulse duration and a fall time. The system further includes a beam delivery and focusing subsystem for delivering and focusing at least a portion of the amplified pulse train onto the target material. The rise time (less than about 1 ns) is fast enough to efficiently couple laser energy to the target material, the pulse duration (typically 2-10 ns) is sufficient to process the target material, and the fall time (a few ns) is rapid enough to prevent the undesirable changes to the material surrounding the target material.

Energy efficient, laser-based method and system for processing target material

An EUV light source is disclosed that may include a laser source, eg CO2 laser, a plasma chamber, and a beam delivery system for passing a laser beam from the laser source into the plasma chamber Embodiments are disclosed which may include one or more of the following; a bypass line may be provided to establish fluid communication between the plasma chamber and the auxiliary chamber, a focusing optic, eg mirror, for focusing the laser beam to a focal spot in the plasma chamber, a steering optic for steering the laser beam focal spot in the plasma chamber, and an optical arrangement for adjusting focal power

Laser produced plasma euv light source

Systems and methods are disclosed for reducing the influence of plasma generated debris on internal components of an EUV light source. In one aspect, an EUV metrology monitor is provided which may have a heater to heat an internal multi-layer filtering mirror to a temperature sufficient to remove deposited debris from the mirror. In another aspect, a device is disclosed for removing plasma generated debris from an EUV light source collector mirror having a different debris deposition rate at different zones on the collector mirror. In a particular aspect, an EUV collector mirror system may comprise a source of hydrogen to combine with Li debris to create LiH on a collector surface; and a sputtering system to sputter LiH from the collector surface. In another aspect, an apparatus for etching debris from a surface of a EUV light source collector mirror with a controlled plasma etch rate is disclosed.

Systems and methods for reducing the influence of plasma-generated debris on the internal components of an EUV light source

A high average power, high brightness solid state laser system. We first produce a seed laser beam with a short pulse duration. A laser amplifier (24) amplifies the seed beam to produce an amplified pulse laser beam which is tightly focused to produce pulses with brightness levels in excess of 1011 Watts/cm2. Preferred embodiments produce an amplified pulse laser beam having an average power in the range of 1 kW, an average pulse frequency of 12,000 pulses per second with pulses having brightness levels in excess of 1014 Watts/cm2 at a 20 micrometers diameter spot which may be steered rapidly to simulate a larger spot size. Alternately, a kHz system with several (for example, seven) beams (from amplifiers arranged in parallel) can each be focused to 20 micrometers and clustered to create effective spot sizes of 100 to 200 micrometers. These beams are useful in producing X-ray sources for lithography.

Low cost, high average power, high brightness solid state laser

A laser system which generates short duration pulses, such as under five nanoseconds at an energy level of up to a few milli-Joules per pulse (mJ/p) with near diffraction limited beam quality. A laser crystal is pumped (excited) by diode lasers. A resonator having at least two mirror surfaces defines a beam path passing through the laser crystal. The beam path in the resonator is periodically blocked by a first optical shutter permitting pump energy to build up in the laser crystal, except for a short period near the end of each pumping period. While the first optical shutter is open a second optical shutter blocks the light in the resonator except for periodic short intervals, the intervals being spaced such that at least one light pulse traveling at the speed of light in the resonator is able to make a plurality of transits through the resonator, increasing in intensity by extracting energy from the excited laser crystal on each transit. After the light pulse has built up in intensity, an optical release mechanism releases the pulse from resonator.

Short pulse laser system

A shaped plasma discharge system is provided in which a shaped radiation source emits radiation at a desired frequency and in a desired shape. In one embodiment, a laser source (10) provides an output beam at a desired intensity level to shaping optics. The shaping optics (30) alters the output beam into a desired shaped illumination field. In an alternate embodiment, plural laser sources provide plural output beams and the shaping optics can produce a compound illumination field. The illumination field strikes a target material (45) forming a plasma of the desired shape that emits radiation with a desired spatial distribution, at a desired wavelength, preferably in the x-ray, soft x-ray, extreme ultraviolet or ultraviolet spectra. In another embodiment an electric discharge generates the required shaped radiation field. The shaped emitted radiation proceeds through an optical system to a photoresist coated wafer, imprinting a pattern on the wafer.

Shaped source of soft x-ray, extreme ultraviolet and ultraviolet radiation

A system and method for generating radiation of a desired wavelength is provided by irradiating microtargets (101, 210). These microtargets (101, 210) are selected from any material that will emit radiation of the desired wavelength. A dispensing apparatus (100, 200) delivers a microtarget into an irradiation zone, where the microtarget is irradiated by an energy source (132). The microtarget (101, 210) may be dispensed in liquid or solid form. Once formed, the desired radiation is directed from the irradiation zone to a beamline while a debris removal arrangement that is in communication with the irradiation zone (117), the energy source (132), and the beamline (142) substantially prevents debris and other pollutants from contaminating the system equipment.

Method and radiation generating system using microtargets

The present invention provides a high gain collimator producing generally uniform intensity profiles for use in lithography and other applications. A focusing optic is also provided. The collimator includes a reflector and guide channel. The guide channel preferably includes polycapillary tubes and/or microchannel plates. The polycapillary tubes are used to collimate or focus the central portion of the x-ray beam in a circular, elliptic, square, or rectangular shape. A conical, parabolic resonance reflector or grazing incidence reflector with a shape similar to the polycapillary collimator is used to increase the solid angle collected and produce a circular, square, etc. annular y-ray beam whose inside dimensions are approximately equal to the exit dimensions of the polycapillary collimator. The annular beam shape, intensity profile and collimation angle is adjusted, if necessary, by an absorber, or polycapillary tubes to provide the desired intensity profile at the exit aperture of the hybrid x-ray collimator optic. A focusing optic is obtained by placing two collimating optics end to end.

Richard M. Foster

Papers

Low cost, high average power, high brightness solid state laser

Short pulse laser system

Shaped source of soft x-ray, extreme ultraviolet and ultraviolet radiation

Method and radiation generating system using microtargets

High collection angle short wavelength radiation collimator and focusing optic