Texas Instruments Incorporated Deutschland, Gmbh

Helmut Rinck

Helmut Endl

Helmut Schneider

The invention relates to a method of measuring the contact angle of wetting liquids on a solid surface with which a high measuring accuracy and better reproduceability of the measurement results is achieved. The method resides in that a laser beam is directed onto the interface line between the liquid and the plane solid surface in such a manner that a first part of the laser beam is reflected by the solid surface and a second part by the liquid surface. The second partial beam is used as measuring beam by determining the angle (.delta.) made between the measuring beam and the solid surface, said angle being in a fixed geometrical relationship to the contact angle (r). The contact angles which can be determined very accurately with this measuring method provide information on wetting properties of materials, the exact knowledge of which is of great significance for example for semiconductor fabrication.

Method of measuring the contact angle of wetting liquid on a solid

An apparatus for wet etching of thin films with which etching rate differences as between various regions of a respective thin film down to only 5% can be achieved. The apparatus includes a housing (10) providing a liquid treatment chamber in which at least one rotational-symmetrical basket (12; 14) is arranged for accommodating semiconductor slices (16) having the thin films to be etched. The basket (12, 14) rests on two rollers (18, 20; 22), one of which is driven. Longitudinally above the basket (12; 14), flat jet nozzles (24) are arranged in such a manner that the jets of etching solution sprayed out of the nozzles form a homogeneous flat jet (26). The flat jet (26) is directed laterally in the direction of the axis of symmetry of the basket (12; 14). With this apparatus, overflow conditions on the surfaces of the slices (16) to be processed are obtained which are so uniform that the apparatus is suitable for use in the wet etching of aluminium layers in device fabrication.

Apparatus for wet etching of thin films

In the etching by means of an etching solution of an electrically conductive layer applied to a substrate the time profile or variation of the diffusion current flowing between the layer to be etched away and the etching solution is measured. The substrate is removed from the etching solution as soon as the diffusion current passes through a steep drop for the second time and assumes a constant value.

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Langenbach, Germany

Helmut Rinck