International Business Machines Corporation

Holger Moritz

Mark Charles Hakey

Dinesh A Badami

Gabor Paal

Gerd Pfeiffer

A positive resist containing a weak base and polyvinyl phenol as a film forming component is deposited on a substrate, subsequently exposed imagewise, cured, blanket exposed and developed in a KOH solution at temperatures of less than 10.degree. C. The resist pattern thus obtained is exposed to light having a wavelength ranging from 300 to 320 nm and finally heat-treated at temperatures ranging from 150.degree. to 280.degree. C. The finished lift-off mask is dimensionally stable at temperatures of .ltoreq.280.degree. C. and does not emit liquid or volatile components when heated. During application of the lift-off mask, a material is blanket vapor deposited at a substrate temperature ranging from about 160.degree. to 250.degree. C. on the resist pattern having openings with overhanging walls. Subsequently, the resist pattern is dissolved in a sodium metasilicate solution, causing the material vapor deposited thereon to be lifted off, with the material deposited on the substrate directly remaining. The lift-off mask is particularly suitable for generating conductor patterns on semiconductor substrates if low and uniform contact resistances between the conductor and the semiconductor material and a high degree of pattern accuracy and packing density are required.

Production of a lift-off mask and its application

An optical photolithographic process in which resist lines having widths in the micron and sub-micron range are produced without the use of a fine line photomask. A positive photoresist having an additive for image reversal is applied to the surface of a semiconductor substrate. The photoresist is exposed through a photomask to ultraviolet light. The edges of the opaque sections of the mask diffract the ultraviolet light, forming partially exposed areas between the exposed and unexposed areas formed in the photoresist. After development in a solvent to remove the exposed areas, the photoresist undergoes an image reversal process. The photoresist is first baked at 100.degree. C. for 30 minutes. During this bake step, the photoactive decomposition products present in the partially exposed areas react, freezing the solubility of the partially exposed areas with respect to that of the unexposed areas. The photoresist is then blanket exposed and developed in a solvent, leaving the partially exposed areas on the substrate. The resulting thin resist lines can be used to form narrow isolation trenches by coating the substrate with a quartz film and lifting off the resist lines.

Process for delineating photoresist lines at pattern edges only using

On the layer 12 a mask 3 corresponding to the desired pattern of holes 15 is provided with via openings 14 having overhanging walls. The layer 12 is selectively etched with a method where the etching attack takes place vertically to the layer surface, and wherein the mask 3 is thinned simultaneously, so that holes 15 are obtained having a cross-section increasing toward the mask 3. If subsequently material 16 for filling the holes 15 is applied in a blanket deposition these holes are completely filled when the material 16 has the same thickness as the layer 12 although the openings over the holes are decreasing with increasing thickness of the material 16. The layer 12 consists preferably of an insulation material, the mask 3 of positive photoresist, and the material 16 of a metal.

Method of making conductive paths through a lamina in a semiconductor

In practice, the development time for a photoresist covered semiconductor wafer exposed by a given mask configuration is established experimentally. It is obvious that this time is only adequate if the other parameters do not change. According to the subject invention the mask is provided with an optical grid. The grid pattern, together with the pattern of the integrated circuit, is transferred by exposure to the photoresist layer covering the semiconductor wafer. During the development process, a light ray is directed onto the area of the wafer which was exposed to the grid pattern and the intensity of the light diffracted in the direction of the 2nd diffraction order is monitored by a light sensor. The slits of the grid may have the same width as the smallest lines of the exposed pattern. In this case, the intensity minimum of the 2nd diffraction order indicates the end of the development process.

Method and system for in situ control of material removal processes

The invention relates to a method of making a negative photoresist image on a substrate, where a normally positive working photoresist material containing 1-hydroxyethyl-2-alkyl-imidazoline is applied to a substrate, image-wise exposed with actinic radiation, heated, and blanket exposed to actinic radiation. The material which was not exposed originally is then removed with a solvent to give a negative image.

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Holzgerlingen, Germany

Holger Moritz