International Business Machines Corporation

Uwe Behringer

Harald Bohlen

Peter Nehmiz

Johann Greschner

Hans-Joachim Trumpp

Werner Kulcke

Werner Zapka

Kurt Datwyler

Peter Vettinger

The invention concerns a method for repairing transmission masks. After the mask has been inspected and the position coordinates of the mask openings have been stored, these position coordinates are compared with the position coordinates of the desired mask pattern to determine the location of defects. The mask to be repaired is then blanket coated on its front side with a photoresist. Particular photoresist regions overlying the mask defects to be repaired are exposed by non-optical or optical radiation for cross-linking the photoresist, the dose required for cross-linking depending upon the respective resist employed. The non-crosslinked portions of the photoresist are subsequently removed. Gold is then applied to the rear of the mask, with the cross-linked photoresist regions acting as a substrate. After the gold has been applied, the cross-linked photoresist regions are removed, typically by plasma etching. Since, after comparison of the position coordinates of mask defects with stored structural mask data, the exposure system exposes and cross-links only the photoresist regions necessary to correct mask defects, mask correction can be carried out within milliseconds.

Method for repairing lithographic transmission masks

A method of making trenches having substantially vertical sidewalls in a silicon substrate using a three level mask comprising a thick photoresist layer, a silicon nitride layer and a thin photoresist layer. Openings are formed in the thin photoresist layer and silicon nitride layer by reactive ion etching in CF.sub.4. The openings are continued through the thick photoresist by etching in an atmosphere containing oxygen. The exposed surface of the silicon substrate is then etched in a CF.sub.4 atmosphere containing a low concentration of fluorine. Also disclosed is a method of making an electron beam transmission mask wherein the openings are made using the three level mask and reactive ion etching of silicon using the etching technique of the invention.

Method of making trenches with substantially vertical sidewalls in

An apparatus and method for testing transmission masks for corpuscular lithography, in which an image of a portion of mask is guided across a pinhole diaphragm, comprising at least one aperture with submicron dimensions, by inclining the corpuscular beam. The relative spacing of two measuring points is derived from the interferometrically measured table displacement and the beam inclination. This test for geometrical errors is effected by placing below the single hold in the diaphragm a scintillator followed by a photomultiplier coupled to an output circuit. For testing the entire mask area for errors and impurity particles, a multihole diaphragm, having submicron apertures arranged in matrix fashion, can be used above an integrated circuit of the charge transfer type which provides a MOS capacitor as a particle detector underneath each diaphragm opening. The exposure mask is scanned in steps, effecting several single exposures at each position by inclining the beam.

Error-corrected corpuscular beam lithography

The photoresist film 12 on the surface of a wafer 11 is exposed through the shadow pattern which is generated by a transmission mask 13 arranged a short distance therefrom when the mask is subjected to a large-area electron beam. The source of the electron beam is an unstructured photocathode 16 on an ultraviolet transparent carrier such as, quartz glass 17 which is subjected to UV radiation from the backside. The electrons exiting from layer 16 are accelerated by a homogeneous electric field 14 towards the mask 13 and shaped to form a homogeneous collimated electron beam. By means of laterally positioned electrostatic deflecting electrodes 19a, 19b, the entire electron beam can be tilted relative to the wafer for adjusting the mask pattern.

Growing community of inventors

Ammerbuch, Germany

Uwe Behringer