International Business Machines Corporation

Karen H Brown

Rangaswamy Srinivasan

Samuel E Blum

Bodil E Braren

David Frank Moore

Kathleen A Perry

Alvin Sugerman

Bernard J Van Der Hoeven, Jr

A method for providing superior fill of features in semiconductor processing utilizes a laser ablation system. Deposition is obtained by ablating target materials which are driven off perpendicular to the target in the direction of the deposition surface. The method provides complete fill of high aspect ratio features with nominal heating of the substrate. Alloys and graded layers, as well as pure metals, can be deposited in low temperature patterned layers. In addition, the system has been used to achieve superior trench filling for isolation structures.

Deposition method for high aspect ratio features using photoablation

This composite back-etch/lift-off stencil method avoids the uncontrolled changes in the properties of contacts in small devices caused by the close proximity of the lift-off resist stencil to the contact area during the precleaning, surface preparation and metal deposition processes. This method limits the area of the wafer exposed to back-etching and thus restores the freedom of choice of contact metallurgy. Back-etching is only applied in the areas of the wafer near to the contact holes; lift-off techniques are used for the rest of the integrated circuit.

Composite back-etch/lift-off stencil for proximity effect minimization

A method for depositing a refractory metal onto a substrate wherein a carbonyl compound vapor of the metal in the vicinity of or on the substrate is photodecomposed by ultraviolet radiation of wavelengths less than 200 nm. This causes the release of atoms of the metal, which then condense onto the substrate. In an example, a tungsten layer is photodeposited by this method onto a GaAs semiconductor layer to form a Schottky barrier diode.

Photo deposition of metals with far UV radiation

A technique is described for the fabrication of devices and circuits using multiple layers of materials, where patterned layers of resists are required to make the device or circuit. The fabrication process is characterized by the selective removal of portions of the resist layer by ablative photodecomposition. This decomposition is caused by the incidence of ultraviolet radiation of wavelengths less than 220 nm, and power densities sufficient to cause fragmentation of resist polymer chains and the immediate escape of the fragmented portions from the resist layer. Energy fluences in excess of 10 mJ/cm.sup.2 /pulse are typically required. The deliverance of a large amount of energy in this wavelength range to the resist layer in a sufficiently short amount of time causes ablation of the polymer chain fragments. No subsequent development step is required for patterning the resist layer.

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Yorktown Heights, NY, United States of America

Karen H Brown