Mask inspection

About: Mask inspection is a research topic. Over the lifetime, 1072 publications have been published within this topic receiving 8696 citations.

Aerial imaging qualification and metrology for source mask optimization

Abstract: As the semiconductor industry moves to 3X technology nodes and below, holistic lithography source mask optimization (SMO) methodology targets an increase in the overall litho performance with improved process windows. The typical complexity of both mask and illumination source exceeds what the lithographic industry has been accustomed to, and presents a novel challenge to mask qualification and metrology. In this paper we demonstrate the latest in aerial imaging technologies of Applied Material's Aera2TM mask inspection tool. The aerial imaging capability opens the door to a wide variety of metrological measurements analysis at aerial level and provides enabling solutions for mask and scanner qualifications. In particular, we demonstrate core and periphery DRAM pattern process window assessment and MEEF measurements, performed on an advanced test mask.

Acceptable defect positioning and manufacturing method for large-scaled photomask blanks

Abstract: Disclosed is an acceptable defect positioning and manufacturing method for large-scaled photomask blanks, where the defective information of the entire large-scaled photomask blanks or etched and to-be-repaired photomask, upon being acquired by a photomask inspection apparatus, is categorized into a critical area a non-critical area. The so-called critical area is directed to areas where defects are unacceptable, while the non-critical area is directed to areas where defects are acceptable. For large-scaled photomask blanks, if all defects are within the non-critical area, the photomask blanks are deemed acceptable. For large-scaled photomasks, photomask acceptance system only needs to reject photomask blanks whose defects are within the critical area of the mask products.

Toward 22 nm: fast and effective intrafield monitoring and optimization of process windows and critical dimension uniformity

Abstract: ITRS lithography's stringent specifications for the 22 nm node are a major challenge for the semiconductor industry. With the EUV point insertion at 16 nm node, ArF lithography is expected to reach its fundamental limits. The prevailing view of holistic lithography methods, together with double patterning techniques, has targeted bringing lithography performance toward the 22 nm node (i.e., closer to the immersion scanner resolution limit) to an acceptable level. At this resolution limit, a mask is the primary contributor of systematic errors within the wafer intrafield domain. As the ITRS critical dimension uniformity (CDU) specification shrinks, it would be crucial to monitor the mask static and dynamic critical dimension (CD) changes in the fab, and use the data to control the intrafield CDU performance in a most efficient way. Furthermore, optimization and monitoring of process windows (PW) becomes more critical due to the presence of mask three-dimensional effects. This paper will present double patterning inter- and intrafield data, for CDU and PW monitoring and optimization, measured by Applied Materials' mask inspection and CD-SEM tools. Special emphasis was given to speed and effectiveness of the inspection for a production environment.

Scanning scattering contrast microscopy for actinic EUV mask inspection

Abstract: Actinic mask inspection for EUV lithography with targeted specification of sensitivity and throughput is a big challenge and effective solutions are needed. We present a novel method for actinic mask inspection, i.e. scanning scattering contrast microscopy. In this method the EUV mask is scanned with a beam of relatively small spot size and the scattered light is recorded with a pixel detector. Since the mask layout is known, the scattering profile of a defect-free mask at the detector can be calculated. The signal between the measured and calculated signal provides the deviation between the real mask and its ideal counterpart and a signal above a certain threshold indicates the existence of a defect within the illumination area. Dynamic software filtering helps to suppress strong diffraction from defect free structures and allows registration of faint defects with high sensitivity. With the continuous scan of the whole mask area, a defect map can be obtained with high throughput. Therefore, we believe that this method has the potential of providing an effective solution for actinic mask inspection. Here we discuss the basic principles of the method, present proof-of-principle experiments, describe the basic components of a feasible stand-alone tool and present early results of the performance estimations of such a tool.

Mask for fabrication of semiconductor devices, process for production of the same, and process for fabrication of semiconductor devices

Abstract: A mask for fabrication of semiconductor devices in which the membrane layer keeps high strength and is free of stress and distortion even though it is made thin. The mask has a membrane-supporting layer at the peripheral part of the mask pattern or the mask pattern region in the membrane layer constituting the mask.