International Business Machines Corporation

Helmut Engelke

Johann Greschner

Harald Bohlen

Peter Nehmiz

Peter Vettiger

Werner Kulcke

Reinhold Muhl

Hans J Trumpp

Erwin Bretscher

A method for automatically splitting a layout of a hole pattern into two complementary arrangements for x-ray, electron beam, ion beams, i.e., particle beam masks. The method determines all inside and outside corners of said pattern and determining a stability value for the pattern so the pattern can be divided into stable sections and alternately distributed over two complementary masks.

Fabrication of particle beam masks

According to this process two partial patterns which, if superimposed upon each other in a predetermined alignment relative to each other yield the desired pattern, with elements of both partial patterns combining to form elements of the pattern, and these partial pattern elements overlapping sectionally, are projected with a suitable radiation onto the radiation-sensitive layers. Overlapping is achieved in that when designing the two partial patterns a pattern corresponding to the desired pattern is used as a basis in that the elements of this pattern are exposed to a negative windage, the negative windage pattern is subsequently partitioned into two negative windage patterns corresponding to the partial patterns, and finally the negative windage partial pattern elements are exposed to a positive windage to the desired size of the partial pattern elements. The method is used in particular when a pattern is to be transferred by means of hole masks, and if it is necessary, e.g. because the pattern shows annular elements, to use instead of one mask only two complementary masks each comprising at least one part of the pattern.

Method of transferring a pattern into a radiation-sensitive layer

For mutually aligning (registering) mask and substrate in X- or corpuscular ray lithography, an electron beam (16) is used which extends collaterally to the exposure beam (ion beam or X-ray) and which is suppressed during the actual exposure process. For coupling the electron beam to the exposure beam path, a magnetic field (7) is used. The accurate relative position of mask and substrate is determined during alignment by tilting the electron beam. Fine alignment during exposure is effected by suitably tilting the ion beam or shifting the substrate relative to the X-ray. The mask (10) used for exposure consists of a very thin silicon layer with a pattern area (M) and a registration area (R) spatially separated therefrom. The registration area consists of a plurality of openings, the pattern area of blind holes.

Mask and system for mutually aligning objects in ray exposure systems

For compensating scattering losses of electrons in photoresists (proximity effect) which influence electron beam lithography by altering the pattern geometry it is suggested to expose selected partial areas of a pattern to an additional irradiation dosage in a second exposure step. For that purpose, a specific mask with corresponding correction openings can be used which is applied with the same, or with a different electron beam intensity. In a particularly advantageous manner the correction of the proximity effect can be achieved when complementary masks are used; the correction openings for the partial areas of the one complementary mask are arranged in the other complementary mask. The proximity effect is then corrected without an additional exposure step. For measuring the proximity effect a photo-optical process is suggested where line patterns with decreasing ridge width in the photoresist are defined through electron beam projection, and where the developing process of the photoresist is discontinued prematurely. The ridge edges which in the presence of the proximity effect are asymmetrical can be easily detected under the microscope.

Method of compensating the proximity effect in electron beam projection

A mask for structuring surface areas and a method for manufacture thereof. The mask includes at least one metal layer with throughgoing apertures which define the mask pattern and a semiconductor substrate for carrying the metal layer. The semiconductor substrate has throughholes that correspond to the mask pattern. The throughholes in the semiconductor substrate extend from the metal layer-covered surface on the front to at least one tubshaped recess which extends from the other back surface into the semiconductor substrate. Holes are provided in a surface layer in the semiconductor substrate. The surface layer differs in its doping from the rest of the substrate and the holes which are provided in the surface layer have lateral dimensions larger than the apertures in the metal layer so that the metal layer protrudes over the surface layer.

Method of making mask for structuring surface areas

A mask for structuring surface areas and a method for manufacture thereof. The mask includes at least one metal layer with throughgoing apertures which define the mask pattern and a semiconductor substrate for carrying the metal layer. The semiconductor substrate has throughholes that correspond to the mask pattern. The throughholes in the semiconductor substrate extend from the metal layer-covered surface on the front to at least one tub-shaped recess which extends from the other back surface into the semiconductor substrate. Holes are provided in a surface layer in the semiconductor substrate. The surface layer differs in its doping from the rest of the substrate and the holes which are provided in the surface layer have lateral dimensions larger than the apertures in the metal layer so that the metal layer protrudes over the surface layer.

Mask for structuring surface areas, and method of making it

A method of pattern exposing an energy beam sensitive target surface to a particle beam by proximity printing, wherein mask alignment errors such as lateral deviations, skew and linear distortions are determined and are effectively corrected by scanning the mask area being transferred with a controllably tilted particle beam, the particle beam having a diameter which is small compared to the area of the mask being scanned. At each scan point the particle beam is controllably tilted in the same azimuth direction as the alignment error for that point and by a tilt angle (taken with respect to the normal direction of the target surface) which has a tangent equal to the product of the magnitude of the alignment error and the separation between the mask and target surface at that point.

Growing community of inventors

Altdorf, Germany

Helmut Engelke