Lithography

About: Lithography is a research topic. Over the lifetime, 23507 publications have been published within this topic receiving 348321 citations.

A litho-only approach to double patterning

Abstract: Double patterning has become one of the candidates to bring us to the next node of the ITRS-roadmap. As an alternative to immersion lithography with higher index fluids and EUV lithography which both require considerable changes in infrastructure, double patterning makes use of the existing infrastructure. Because of this, double patterning has gained considerable attention during the past few years. It has become a serious candidate to reach the 45 nm node and even the 32 nm node. Most of the currently known double patterning techniques have relatively complex process flows, which may prevent them from being used in production. One of the complicating factors is the use of an etch step in between the two lithography steps. This etch step is necessary to transfer the pattern of the first resist layer into an underlying hard mask before a second exposure can be done. Another complicating element, arising in several known double patterning techniques, is the translation of overlay error in CD-error. This translation occurs when a feature is printed in two exposures, i.e. not features but the spaces between them are patterned, patterning the left and right edge of a feature in different exposures. In this paper, we examine and evaluate a novel double patterning method that does not include transfer etch in between the lithography steps. This method would simplify the double patterning process. Furthermore, each feature is patterned completely in one exposure, for which CD-value is not affected by overlay error. This paper discusses the feasibility of the new double patterning method and compares it to conventional double patterning schemes. Furthermore, an assessment will be made whether the proposed technique has the potential to be used in production.

Fabrication and characterization of surface micromachined capacitive ultrasonic immersion transducers

Abstract: In this paper, several innovative steps used in fabricating surface micromachined capacitive ultrasonic immersion transducers are reported. The investigation is focused on major steps in the device fabrication processes necessary to optimize transducer performance. Such steps include membrane formation, vacuum sealing, and electrode metallization. Three transducer membrane structures are evaluated: a nitride membrane with an oxide sacrificial layer; a polysilicon membrane with an oxide sacrificial layer; and a nitride membrane with a polysilicon sacrificial layer. Three vacuum sealing mechanisms are compared, each of which requires a different degree of lithographic sophistication, uses a particular sealing mechanism, and results in a sealed cavity. Submicrometer via sealing requires sophisticated lithography but is amenable to LPCVD nitride, LTO, and other sealing procedures. Standard g-line lithography results in vies which seal only with high sticking coefficient species, such as LTO. A novel etch channel structure, which results in lateral sealing and requires neither sophisticated lithography nor a particular sealing material, is demonstrated. Finally, the impact of electrode metallization on the impedance, bandwidth, and efficiency of the transducers is discussed. The experiments in the paper are guided by theoretical analysis and computer simulations when applicable. The new process results in optimized devices which have a broad-band 50-/spl Omega/ real part impedance in the megahertz range. A transducer dynamic range in excess of 100 dB is achieved around 4.5 MHz. An untuned transducer exhibits more than 100% bandwidth when connected to electronics with 50-/spl Omega/ input impedance. In addition, beam pattern measurement shows the immersion devices behave like uniform piston transducers and are readily suitable for array applications. The fabrication techniques and results herein reported indicate that surface micromachined ultrasonic immersion transducers are an attractive alternative to piezoelectric transducers in immersion applications.

Problems of the nanoimprinting technique for nanometer scale pattern definition

Abstract: We have tested nanoimprint lithography, a new and promising technique for nanometer-scale pattern definition. Preliminary experiments reveal that, besides severe sticking and adhesion problems, the problem of material transport is one inherent to this technique. There are clear indications that most of the effects found may be understood in terms of material transport. We performed experiments within a well defined pressure and temperature window which ranged from 60 to 100 bar and from 50 to 90 °C above the glass transition temperature of the poly(methylmethacrylate)-like polymer used. As a result, the quality of imprint is evaluated with respect to full area pattern transfer, based on a qualitative scanning electron microscope investigation of the fully imprinted area of 2 cm × 2 cm patterned with features of different size and shape. Optimum conditions for imprint quality are found around 100 bar and 90 °C above Tg for the specific polymer used. Although material transport will limit nanoimprint perfor...

Nano-compact disks with 400 Gbit/in2 storage density fabricated using nanoimprint lithography and read with proximal probe

Abstract: Nano-compact disks (Nano-CDs) with 400 Gbit/in2 topographical bit density (nearly three orders of magnitude higher than commercial CDs) have been fabricated using nanoimprint lithography. The reading and wearing of such Nano-CDs have been studied using scanning proximal probe methods. Using a tapping mode, a Nano-CD was read 1000 times without any detectable degradation of the disk or the silicon probe tip. In accelerated wear tests with a contact mode, the damage threshold was found to be 19 μN. This indicates that in a tapping mode, both the Nano-CD and silicon probe tip should have a lifetime that is at least four orders of magnitude longer than that at the damage threshold.

Mussel-inspired block copolymer lithography for low surface energy materials of teflon, graphene, and gold.

Abstract: Mussel-inspired interfacial engineering is synergistically integrated with block copolymer (BCP) lithography for the surface nanopatterning of low surface energy substrate materials, including, Teflon, graphene, and gold. The image shows the Teflon nanowires and their excellent superhydrophobicity.