International Business Machines Corporation

Kenneth Christopher Racette

Michael Straight Hibbs

Marie Angelopoulos

Katherina E Babich

S Jay Chey

Arpan Pravin Mahorowala

Robert Neal Lang

Cameron James Brooks

C Richard Guarnieri

Max Gerald Levy

Emily Gallagher

Michael James Lercel

Andrew J Watts

Robert James Nolan

Rogert K Leidy

Nancy Chenxin Zhou

The present invention describes a structure and method for reducing or eliminating the flatness distortion effects of a photomask assembly which occurs when a pellicle is mounted to the photomask. The invention is to perform a partial disconnection of the mounting area of the pellicle frame from the print area of the mask. An exemplary embodiment of the present invention achieves the distortion reduction or elimination using a trench in the photomask as the partial disconnection.

Method for reducing photo-mask distortion

In a projection apparatus for projecting optical images, an optical mask support stage having a pair of separated arms. Each arm being provided with a respective mask chucking bar that supports a respective edge of a thin glass mask and applies to the respective edge a bending moment away from the center of the mask to reduce or eliminate any gravitational induced sag in the center of the mask thereby improving the quality of the images projected by the apparatus.

Method and apparatus for correcting gravitational sag in photomasks used in the production of electronic devices

A monolithic optical pellicle and method of making used to protect a photomask during photolithography processing. The monolithic optical pellicle is comprised of a pellicle plate having a recessed central portion integrally formed with a perimeter frame of the pellicle plate such that it is a one-piece optical pellicle. The monolithic optical pellicle comprises a material of sufficient rigidity to minimize distortions in and maximize durability of the pellicle when used in combination with the recessed portion having a thickness that prevents sagging thereof due to applied forces on the resultant monolithic optical pellicle. This recessed central portion is the optical pellicle portion of the present monolithic optical pellicle, while the integral perimeter frame is used to attach the monolithic optical pellicle at the desired stand-off distance to a photomask. The monolithic optical pellicle preferably comprises a material that is transparent to an exposure field at about 157 nm wavelengths.

Monolithic hard pellicle

An attenuating embedded phase shift photomask blank that produces a phase shift of the transmitted light is formed with an optically translucent film made of metal, silicon, nitrogen and oxygen. An etch stop layer is added to improve the etch selectivity of the phase shifting layer. A wide range of optical transmission (0.001% up to 15% at 157 nm) is obtained by this process.

Attenuated embedded phase shift photomask blanks

An attenuating embedded phase shift photomask blank that produces a phase shift of the transmitted light is formed with an optically translucent film made of metal, silicon, nitrogen or metal, silicon, nitrogen and oxygen. A wide range of optical transmission (0.001% up to 20% at 193 nm) is obtained by this process. A post deposition process is implemented to obtain the desired properties (stability of optical properties with respect to laser irradiation and acid treatment) for use in industry. A special fabrication process for the sputter target is implemented to lower the defects of the film.

A thin transition-metal based scattering layer of a mask blank for use in EPL systems is formed by providing the thin transition-metal scattering layer directly over membrane layers on a lot of substrates, thereby forming a continuous contact between the single transition metal-based scattering layer and the membrane layer. Preferably, the single transition metal-based scattering layer is a single tantalum-silicon composite scattering layer having a stoichiometry of Ta Si. The deposition parameters for depositing the thin transition-metal based scattering layer are adjusted to provide the scattering layer uniformly over all substrates within the lot. A first substrate from the lot of substrates is then selected, an initial stress measurement of the scattering layer is determined and then the substrate is annealed at a first temperature. The stress of the scattering layer over the first annealed substrate is determined, and subsequently the anneal temperature is adjusted based on a comparison between the pre-anneal, initial stress measurement and the post-annealed stress measurement. A second substrate from the lot of substrates is then selected, annealed at the adjusted temperature, stress measurement of the scattering layer of the second substrate is determined, and the anneal temperature may once again be adjusted. The above process is repeated until a targeted stress level of the thin transition-metal based scattering layer of the mask blank has been obtained. The thin scattering layer is adapted to have final film stress controllable to within &plusmn;10% of the targeted stress.

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Fairfax, VT, United States of America

Kenneth Christopher Racette