International Business Machines Corporation

Werner Zapka

Klaus Meissner

Joachim H Keyser

Karl Asch

Holger Hinkel

Harald Bohlen

Peter Nehmiz

Werner Steiner

Gerhard Elsner

Hans-Joachim Trumpp

Upali Bandara

Reinhold Muhl

Otto Koblinger

Jurgen Kempf

Uwe Behringer

Volker Heinrich

Artur Lang

Erwin Prinz

In the course of the process for making masks with structures in the submicrometer range, initially structures of photoresist or polymer material with horizontal and substantially vertical sidewalls are produced on a silicon substrate covered with an oxide layer. This is followed by a layer of silicon nitride which is deposited by LPCVD. The resultant structure is planarized with a photoresist which is etched back until the start of the vertical edges of the sidewall coating formed by the nitride layer is bared on the photoresist structures. In a photolithographic step, a trimming mask is produced on the surface of the nitride layer and the planarizing resist. The bared regions of the nitride layer are then removed by isotropic etching. The dimensions A-B of the openings defined after removal of the nitride layer from the vertical surfaces of the photoresist structures are transferred to the oxide layer by anisotropic etching. Concurrently with these structures of minimum line width, registration marks are generated which allow the adjustment necessary for a further photolithographic step to be carried out with maximum accuracy. After removal of the trimming mask, the planarizing resist, the photoresist structures and the remainder of the nitride layer, structures with coarser line widths are defined in a further photolithographic step, which are also transferred to the oxide layer. Using the oxide layer as a mask, trenches of the desired depth are produced in the silicon substrate by anisotropic etching. The mask is thinned by anisotropic etching, and the oxide layers are removed from the front and the back side by wet etching.

Process for making masks with structures in the submicron range

To remove small particles from surfaces of solid bodies at least one laser pulse of high power density (excimer laser) is directed onto the surface. The method is particularly suited to clean Si-masks used in electron-beam lithographic devices. An arrangement for in-situ-cleaning of masks in accordance to this method is integrated in such an electron-beam lithographic device.

Removal of particles from solid-state surfaces by laser bombardment

A mask for radiation beam lithography is formed from a semiconductor wafer by thinning a region into a membrane with a hole pattern defining the pattern of the mask. The membrane is doped with a tensile stress-generating material so that minimum doping exists at the periphery of the membrane with the maximum at its center. The difference in doping between the periphery and the center is chosen so that when the mask is irradiated with a given beam current intensity, the membrane is tension-free. To make a mask in the wafer, a hole pattern is formed by etching holes in the membrane or by depositing a layer on the membrane. The wafer is thinned from the opposite surface until the holes in the hole pattern are throughholes or until the desired thickness is reached. The membrane is doped with tensile-stress-generating material using ion implantation or diffusion proportionally to the temperature distribution existing in the membrane during irradiation with exposure beams.

Mask for ion, electron or X-ray lithography and method of making it

Method for measuring the properties of a slider/disk interface in a magnetic disk storage apparatus by measuring a triboelectric current flowing between disk and slider. Rotational speed is adjusted between 100 and 500 rpm so as to obtain a frictional contact between disk and slider. The shape of the tribo current curve obtained during the measuring time interval is analyzed. An early maximum of the tribo current amplitude and a subsequent continual decay indicates a good slider/disk interface and a long lifetime.

System for testing magnetic head/disk interfaces

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

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Gaertringen-Rohrau, Germany

Werner Zapka