Phase-shift mask

About: Phase-shift mask is a research topic. Over the lifetime, 2088 publications have been published within this topic receiving 18058 citations.

Optical superlattices—a strategy for designing phase-shift masks for photolithography at 248 and 193 nm: Application to {AlN/CrN}

Abstract: This letter illustrates with AlN/CrN multilayers that optical superlattices, comprised of multilayers of a uv transmitting dielectric layer and a metallic layer, offer a systematic approach to design and fabricate partially transmitting, phase-shift masks for photolithography. From the measured optical constants of sputtered AlN/CrN multilayers, it was found that films had π-phase shift and tunable optical transmission between 5% and 15% at 365, 248, and 193 nm. We compared the optical properties of sputtered AlN/CrN multilayers to “ideal” superlattices, calculated from the measured optical properties of individual thick CrN and AlN layers, and to compositionally equivalent psuedobinary alloys of (AlN)1−x(CrN)x. Although optical properties for all three systems were nearly the same, which is attractive because it implies wide process lattitude, we found systematic differences that were attributed to their individual structures. A phase shift mask with 6% transmission at 365 nm was fabricated with a 1650-A-thick (25 A AlN+25 A CrN) multilayer film.

Alternating phase-shifted mask for logic gate levels, design, and mask manufacturing

Abstract: While the benefits of alternating phase shifted masks in improving lithographic process windows at increased resolution are well known throughout the lithography community, broad implementation of this potentially powerful technique has been slow due to the inherent complexity of the layout design and mask manufacturing process. This paper will review a project undertaken at IBM's Semiconductor Research and Development Center and Mask Manufacturing and Development facility to understand the technical and logistical issues associated with the application of alternating phase shifted mask technology to the gate level of a full microprocessor chip. The work presented here depicts an important milestone toward integration of alternating phase shifted masks into the manufacturing process by demonstrating an automated design solution and yielding a functional alternating phase shifted mask. The design conversion of the microprocessor gate level to a conjugate twin shifter alternating phase shift layout was accomplished with IBM's internal design system that automatically scaled the design, added required phase regions, and resolved phase conflicts. The subsequent fabrication of a nearly defect free phase shifted mask, as verified by SEM based die to die inspection, highlights the maturity of the alternating phase shifted mask manufacturing process in IBM's internal mask facility. Well defined and recognized challenges in mask inspection and repair remain and the layout of alternating phase shifted masks present a design and data preparation overhead, but the data presented here demonstrate the feasibility of designing and building manufacturing quality alternating phase shifted masks for the gate level of a microprocessor.

Method of chromeless phase shift mask fabrication suitable for auto-cad layout

Abstract: A method for forming chromeless phase shifting photomasks is provided. The photomasks include a transparent substrate and raised phase shifters formed with a vertical edge and a tapered edge. During a lithographic process using the photomask, the vertical edges of the phase shifters form nulls on a photoresist covered wafer. The tapered edge prevents the formation of undesirable stringers on the wafer. The method of the invention includes the steps of: forming an opaque etch mask including a pattern of opaque features on a transparent substrate; forming a layer of resist over one sidewall of each opaque feature; and then etching the photoresist with one etching species and the substrate with another etching species to form chromeless phase shifters each having a vertical edge and a tapered edge.

Step and repeat apparatus having enhanced accuracy and increased throughput

Abstract: A multi-station Step and Repeat Apparatus (Stepper) for imaging semiconductor wafers. The stepper has at least 2 stations, at least one of which is for imaging. The second station may be used for image field characterization, or image defect correction, or for Phase Shift Mask (PSM) loop cutting. Multiple laser beams directed in orthogonal directions provide interferometric monitoring to track wafer locations for wafers on the stepper.

Halftone phase shift mask and method for manufacturing the same

Abstract: PROBLEM TO BE SOLVED: To provide a halftone phase shift mask that can significantly improve CD (critical dimension) performance, and to provide a method for manufacturing the mask. SOLUTION: The halftone phase shift mask has an engraved portion in a substrate transparent to exposure light so as to control the phase of transmitted light, and is characterized in that a light shielding film provided in a portion adjacent to the engraved portion of the substrate or in a peripheral portion of the substrate includes a film (A) made of a material which can be etched in an etching process using an etching gas essentially comprising a fluorine-based gas. COPYRIGHT: (C)2007,JPO&INPIT