A nonlinear crystal including stacked strontium tetraborate SrB.sub.4O.sub.7 (SBO) crystal plates that are cooperatively configured to create a periodic structure for quasi-phase-matching (QPM) is used in the final frequency doubling stage of a laser assembly to generate laser output light having a wavelength in the range of about 180 nm to 200 nm. One or more fundamental laser beams are frequency doubled, down-converted and/or summed using one or more frequency conversion stages to generate an intermediate frequency light with a corresponding wavelength in the range of about 360 nm to 400 nm, and then the final frequency converting stage utilizes the nonlinear crystal to double the frequency of the intermediate frequency light to generate the desired laser output light at high power. Methods, inspection systems, lithography systems and cutting systems incorporating the laser assembly are also described.

An inspection system includes a stage unit configured to load a blank mask thereon. A side illumination unit, which is disposed to face a side surface of the blank mask and includes a plurality of LEDs, is provided. A camera disposed adjacent to the blank mask is provided. An inspection light beam irradiated from the side illumination unit toward the side surface of the blank mask is substantially parallel to an upper surface of the blank mask.

Disclosed are methods and apparatus for qualifying a photolithographic reticle. A reticle inspection tool is used to acquire images at different imaging configurations from each of a plurality of pattern areas of a test reticle. A reticle near field for each of the pattern areas of the test reticle is recovered based on the acquired images from each pattern area of the test reticle. A lithography model is applied to the reticle near field for the test reticle to simulate a plurality of test wafer images, and the simulated test wafer images are analyzed to determine whether the test reticle will likely result in an unstable or defective wafer.

A method for inspecting a reticle including a reflective layer on a reticle substrate is provided. The method may include loading the reticle on a stage, cooling the reticle substrate to a temperature lower than a room temperature, irradiating a laser beam to the reflective layer on the reticle substrate, receiving the laser beam using a photodetector to obtain an image of the reflective layer, and detect a particle defect on the reflective layer or a void defect in the reflective layer based on the image of the reflective layer.

An inspection method for inspecting a substrate by using an optical image obtained by irradiating the substrate with light from a light source through an optical unit, and causing the light reflected by the substrate to be incident to a sensor, includes adjusting a focus offset value such that a focal distance for setting the signal-to-noise ratio of a programmed defect to the maximum level, is obtained by acquiring the optical image while changing a focal distance between the surface in which a first pattern is provided and the optical unit. The substrate includes the first pattern, a second pattern on the same plane as the first pattern, the programmed defect in the second pattern, and a third pattern on the same plane as the first pattern. The existence of a defect is detected by acquiring the optical image of the first pattern after the focus offset is adjusted.

Process window qualification (PWQ) layouts can be used to determine a presence of a pattern anomaly associated with the pattern, patterning process, or patterning apparatus. For example, a modulated die or field can be compared to a slightly lower offset modulated die or field. In another example, the high to low corners for a particular condition or combination of conditions are compared. In yet another example, process modulation parameters can be used to estimate criticality of particular weak points of interest.

A method for ascertaining distortion properties of an optical system in a measurement system for microlithography is provided, wherein the optical system images at least one structure to be measured into a measurement image. In accordance with one aspect, a method according to the invention comprises the following steps: measuring the field-dependent image aberrations of the optical system; determining a first distortion pattern present in the first image field generated by the optical system during measurement of at least one predefined structure; carrying out an optical forward simulation for the predefined structure taking account of the field-dependent image aberrations measured previously, with a second image field being generated; determining a second distortion pattern for the second image field generated previously; and ascertaining the structure-independent distortion properties of the optical system by calculating a third distortion pattern as the difference between the first distortion pattern and the second distortion pattern.

In an inspection apparatus according to one aspect of the present invention, a processing apparatus includes: a profile data generation unit that divides each of a plurality of images according to a circumferential position to generate profile data in which a radial direction position and luminance data are associated with each other; a deconvolution operation unit that carries out a deconvolution operation using a one-dimensional point spread function to generate deconvolution operation data based on the profile data; an estimation unit that estimates estimation data of the deconvolution operation data in a desired focus position in the optical axis direction using the deconvolution operation data; and a synthesis unit that synthesizes the estimation data estimated by the estimation unit for each radial direction position to generate the image in the desired focus position.

Disclosed are methods and apparatus for inspecting a photolithographic reticle. An inspection tool is used to obtain a plurality of patch area images of each patch area of each die of a set of identical dies on a reticle. An integrated intensity value for each patch area image is determined. A gain is applied to the integrated intensity value for each patch area image based on a pattern sparseness metric of such patch area image and its relative value to other patch area images' pattern sparseness metric. A difference between the integrated intensity value of each patch of pairs of the dies, which each pair includes a test die and a reference die, is determined to form a difference intensity map of the reticle. The difference intensity map correlates with a feature characteristic variation that depends on feature edges of the reticle.

A laser assembly for generating laser output light at an output wavelength of approximately 183 nm includes a fundamental laser, an optical parametric system (OPS), a fifth harmonic generator, and a frequency mixing module. The fundamental laser generates fundamental light at a fundamental frequency. The OPS generates a down-converted signal at a down-converted frequency. The fifth harmonic generator generates a fifth harmonic of the fundamental light. The frequency mixing module mixes the down-converted signal and the fifth harmonic to produce the laser output light at a frequency equal to a sum of the fifth harmonic frequency and the down-converted frequency. The OPS generates the down-converted signal by generating a down-converted seed signal at the down-converted frequency, and then mixing the down-converted seed signal with a portion of the fundamental light. At least one of the frequency mixing, frequency conversion or harmonic generation utilizes an annealed, deuterium-treated or hydrogen-treated CLBO crystal.