Mask inspection

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

Inspection of production alternating PSM reticles using UV-based 365-nm reticle inspection tool

Abstract: The paper presents results of a thorough study using the UV-based die-to-database mask inspection system ARISTM100i for the inspection of alternating phase shifting masks (AAPSM) designed for ArF (193nm) technology. Specially designed test masks were used to investigate sensitivity limitations of the i-line tool. Main focus is on phase errors, which were treated as a function of defect size, phase, and mask location. In addition, production reticles were inspected using a specially developed sensitivity AAPSM. Production issues like false defect rate and data preparation were addressed. The paper is concluded with a short printability analysis of different phase defects detected during the experiment.

A novel approach to mask defect inspection

Abstract: Memory chips, now constituting a major part of semiconductor market, posit a special challenge for inspection, as they are generally produced with the smallest half-pitch available with today's technology. This is true, in particular, to photomasks of advanced memory devices, which are at the forefront of the "low-k1" regime. In this paper we present a novel photomask inspection approach, that is particularly suitable for low-k1 layers of advanced memory chips, owing to their typical dense and periodic structure. The method we present can produce a very strong signal for small mask defects, by suppression of the modulation of the pattern's image. Unlike dark-field detection, however, here a single diffraction order associated with the pattern generates a constant "gray" background image, that is used for signal enhancement. We define the theoretical basis for the new detection technique, and show, both analytically and numerically, that it can easily achieve a detection line past the printability spec, and that in cases it is at least as sensitive as high-resolution based detection. We also demonstrate this claim experimentally on a customer mask, using the platform of Applied Material's newly released Aera2 TM mask inspection tool. The high sensitivity demonstrates the important and often overlooked concept that resolution is not synonymous with sensitivity. The novel detection method is advantageous in several other aspects, such as the very simple implementation, the high throughput, and the relatively simple pre- and post-processing algorithms required for signal extraction. These features, and in particular the very high sensitivity, make this novel detection method an attractive inspection option for advanced memory devices.

Mask inspection apparatus and mask inspection method

Abstract: A mask inspection apparatus includes irradiation means for irradiating a sample with an electron beam, electron detection means for detecting a quantity of electrons generated from the sample having a pattern formed thereon by the irradiation with the electron beam, image processing means for generating image data of the pattern on the basis of the quantity of the electrons, and control means for creating a line profile and a differential profile of the pattern formed on the sample on the basis of the quantity of the electrons detected by the electron detection means The control means detects a rising edge and a falling edge of the pattern on the basis of the differential profile, and then generates mask data of a multi-level structure on the basis of data of the edges and the image data created by the image processing means

Mask Inspection Technology for 65nm (hp) Technology Node and Beyond

Abstract: The application of the high numerical aperture, 193nm‐ArF laser exposure system is expected to be extended to 65nm node device production and beyond. The extension of 193nm lithography means that the pattern transfer using this exposure system is done under lower k1 condition than previously. This leads to the increase of mask error enhancement factor (MEEF) in the exposure process. Since mask critical dimension (CD) uniformity and defects on a mask are more difficult to control, defect detection consistency with lithography wavelength for the mask inspection system is strongly required. A novel high‐resolution mask inspection platform is developed to enable the high‐quality mask defect inspection for 65–45nm node. The system is operated at wavelength of 198.5nm, which wavelength is nearly equal to that of the 193nm‐ArF laser exposure system. The defect detection performance of 20–60nm defect detection sensitivity is certified at the early stage test. The system capabilities for 65nm node inspection and beyond are shown. And the possibility of reflected light inspection and die‐to‐wafer image (D/WI) inspection for 45nm node inspection are also reported.

Preliminary study on systematic optimization of EPL mask infrastructure

Abstract: Electron projection lithography (EPL) has high-resolution capability of meeting the 65 nm technology node and beyond. A first-generation EPL has been developed and improved at Nikon and Selete. Defect free mask is indispensable for successful introduction of this technology into the production stage. However, an EPL mask is considerably different from today's optical photomask, especially due to its 3-D structure. Hence the conventional methods of quality assurance used for optical photomask are not applicable for EPL mask. Selete is now developing a series of defect inspection and repair systems for an EPL stencil mask infrastructure. In our previous work we reported on the individual systems for defect inspection and mask repair by using programmed defects. Moreover, we verified a number of the defect inspection and repair systems through a sequential process. In this work the motivation is to investigate relationship issues among these tools for future applications, such as defect printability, CD controllability, calibration, optimization, performance matching, and automated operation.