Showing papers on "Mask inspection published in 1990"

Inspection method of photomask reticle for semiconductor device fabrication

Abstract: A method of inspecting a photomask reticle for the fabrication of a semiconductor device such as a die having a first pattern which has its own individual shape and a plurality of second patterns each having the same shape and size among themselves, combining the methods of the database inspection and of the pattern comparing inspection. The method of database inspection is applied to the first pattern and to one of the second patterns selected randomly. The database inspection can be performed by comparison with inspection data derived from design data used for the fabrication of the photomask reticle, such as by an improved reticle tester which can exclude all of the second patterns except the selected one of the second patterns. The second patterns other than the selected pattern are then inspected by the method of the pattern comparing inspection, that is, by comparison with the selected second pattern which has already been inspected by the database inspection. The volume of the storage for the inspection data and the time required to inspect the photomask reticle can be reduced to less than one fourth of those in the prior art inspection method, while maintaining high accuracy in the inspection of photomask reticles.

Lithography mask inspection

Abstract: A method of detecting defects in a lithography mask by exposing a first mask onto a positive resist, and a second, ostensibly identical mask onto a negative resist. Remaining particles of resist after development correspond to spots in the first mask, or to holes in the second mask. The process may be repeated with the tones of the resists reversed to detect holes in the first mask, or spots in the second mask.

Mask inspection device

Abstract: PURPOSE:To carry out high spatial resolution by detecting a mask pattern image and collating this pattern image with a reference standard pattern image and detecting the flaw of the mask to be detected. CONSTITUTION:X-rays emitted from an X-ray source 201 are passed through a converging optical element 202 and a fine X-ray spot is formed on the pattern of a mask 203 to be detected. X-rays passed through the mask 203 are detected with a detector 206 and converted into a digital signal with a detector circuit 207 and an X-ray mask detection picture image is obtained. On the other hand, the X-ray mask design data sent from a CAD system are converted into a format and thereafter this format is stored in a hard disk 302. The data for electron beam plotting stored in the disk 302 are converted into the dot pattern data with a dot conversion circuit 303. The intensity distribution of the fine spot is superposed with a reference data conversion circuit 304 and the reference data are obtained. This reference data are compared with the X-ray mask measurement data with a data comparison circuit 306 to perform decision of a flaw.

Inspection of reticle

Abstract: PURPOSE:To quickly examine fine foreign matter and any fault on and in a reticle under a conditions more similar to an actual photography process by directly transferring a reticle pattern on a photoresist film or a CEL film for its inspection. CONSTITUTION:A photoresist film 2 involving an absorbent is formed on a surface of a quartz glass plate 1 by a coating process, the absorbent absorving 90% or more of a light having 500nm or longer wavelengths. The photoresist film 2 is exposed to the light and patterned with a reticle 3 to be inspected as a mask to transfer a pattern 4 of the reticle 3. The quartz glass plate 1 so processed is set in a transmission type mask inspection device having a light source from which 500nm or shorter wavelengths have been removed using a filter, for inspecting any pattern fault. Hereby, fine foreign matter and any fault existent on and in a reticle can quickly be inspected in a condition which more resembles an actual photography process.

Applied use of advanced inspection systems to measure, reduce, and control defect densities

Abstract: Just as the photolithography engineer has tools andmethods for identifying and correcting stepper alignment errors, the defect reduction engineer needs tools and methods for identifying and eliminating process defects. Automated defect inspection systems are becoming increasingly common in semiconductor manufacturing operations. It has become accepted that they provide the quickest, most reliable method of identifying and reducing defect causes. In addition to automated inspection systems, a sound inspection strategy is necessary. Techniques have been presented by this author and others 1,2 describe a process of identifying defect types, isolating sources, performing and verifying corrective action. A variety of inspection systems are available to implement these techniques. This paper examines the application of two automated inspection systems in a semiconductor fabrication line producing two level metal, single layer polycide CMOS ASICS. Statistical methods for interpreting inspection results and verifying defect reduction are also shown. The results presented show the benefits of this approach. Device yield can be greatly improved, and critical information about the variability and density of yield limiting defects in a fabrication process can be provided. Scope This report consists of two individual studies. In the first study, the processes of defect identification, source isolation, corrective action, and verification are investigated on production wafers following the active area etch operation. A patterned wafer laser scanning particle detection system is used to collect the data for these processes. In the second study the initial step of defect identification is investigated on a polycide etch layer. Data from a laser scanning paiticle detection system and a digital image processing system are analyzed.