Showing papers on "Photomask published in 1975"

Apparatus for detecting the defects of the mask pattern using spatial filtering

Abstract: Two kinds of light sources, one of which emits a coherent light and the other of which emits incoherent light, are provided. The coherent light and incoherent light respectively emitted from the two different kinds of light sources, proceed on the same optical axis. A photomask, such as for an integrated-circuit, or other objects, which have linear straight line features and nonlinear defects, are simultaneously illuminated by the coherent light and incoherent light. The two kinds of light which pass through the photomask or other objects are transformed into a Fourier-transform pattern by a transform lens. A spatial filter, having a plurality of arms which extend in predetermined directions from the center thereof, is provided on the focal plane of the transform lens. The spatial filter suppresses the passing of coherent light having information of the linear straight line features. The coherent light which has information of the defects of the photomask is not suppressed by the spatial filter. The coherent light and incoherent light passing through the spatial filter are directed to an image plane. As a result thereof, an image of the photomask or other object, obtained by the incoherent light and an image of the defects of the photomask or other objects obtained by the coherent light, are simultaneously projected on each other on the image plane.

Instrumentation for conformable photomask lithography

Abstract: A vacuum frame and a multiple mask alignment system for conformable photomask lithography are described. These instruments greatly improve the convenience and adaptability of conformable photomask lithography and may permit the advantages of improved resolution, dimensional control, photoresist profile control, and reduced mask damage to be realized in routine photolithographic production.

Method of munufacturing of semiconductor device

Abstract: PURPOSE: To be able to locate an exact position of the photomask by means of a formation of a pattern for locationing a very simple and exact position on a wafer of the semiconductor. COPYRIGHT: (C)1976,JPO&Japio

Photolithographic linewidth control

Abstract: A simple model for the image formation process in photoresist is proposed based on Fresnel diffraction from the edge of a mask feature. It is shown theoretically and verified experimentally that the dimensional difference between a clear mask feature and its image in photoresist is given by aL½[ ln (E i ) - ln (E T ) + ln (K) ] where a and K are constants peculiar to the exposure optics, L is the separation between mask and silicon wafer, E i is the exposure energy, and E T is the effective exposure energy threshold of the photoresist. The model is used to show the existence of "optimum" exposure ratios E i /E T which minimize image variability in hard-, soft-, and near-contact printing. Control of this exposure ratio is found to be the key to successful use of off-contact printing. Based on this model, a photolithographic process control system is outlined in which exposure tool operation and photoresist processing parameters are characterized and monitored with a single silicon wafer. The system is equally applicable to photomask fabrication.

Method for measuring the size of thin plane

Abstract: PURPOSE: Photomask is adsorped and held on the flat surface of the backupplate to measure the size of photomask exactly. COPYRIGHT: (C)1977,JPO&Japio

Production of photomasks by forming complex of silver and diazonium or pyrylium salts

Abstract: A photomask comprising a support that is transparent to ultra-violet radiation and visible light and a layer incorporating a photomask image, the image parts of which contain a complex compound of a silver halide and a diazonium, pyrylium, or thiapyrylium salt, wherein said complex compound is substantially opaque to ultra-violet radiation and blue light but substantially transmitting visible light in the wavelength range above 500 nm.