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Optical components are the main parts in laser systems and also the limiting factor for high power laser. All-silica based optical components proved to have extremely high laser induced damage threshold and were already tested on standard glass substrates. Such coatings are fabricated by employing glancing angle deposition method, combination of nanostructured porous low refractive index and dense high refractive index thin films were fabricated. Anti-reflection coatings and mirrors with required reflection were achieved, which have superior LIDT values (50.7 J/cm2). Antireflection coating was deposited directly on BBO crystal and results are demonstrated. In this work, the possibility to improve microlaser systems with all-silica coatings is presented.

CILAS is involved in a scientific project for SRON Netherlands Institute for Space Research, on the development of multilayer coatings for the silicon immersed grating prism, which is a key component of the short-wave-infrared (SWIR) channel of the TROPOMI imaging spectrometer. For the project, two specific coatings have been implemented and qualified by CILAS: first, an antireflection coating deposited on the entrance and exit facets of the immersed grating prism, which reaches a very low value of reflectivity in the infrared [2305nm; 2385nm] spectral range and for a wide angular range [0° to 47°] of incidence of the transmitted light, and second, a metal-dielectric absorbing coating for the third facet of the prism to eliminate parasitic light inside the silicon prism.

For the sol-gel method, it is still challenging to achieve excellent spectral performance when preparing antireflection (AR) coating by this way. The difficulty lies in controlling the film thickness accurately. To correct the thickness error of sol-gel coating, a hybrid approach that combined conventional sol-gel process with ion-beam etching technology was proposed in this work. The etching rate was carefully adjusted and calibrated to a relatively low value for removing the redundant material. Using atomic force microscope (AFM), it has been demonstrated that film surface morphology will not be changed in this process. After correcting the thickness error, an AR coating working at 1064 nm was prepared with transmittance higher than 99.5%.

We present a general analytical synthesis method to design quarter-wave dielectric multilayers exhibiting reflection properties which approximate a given reflection spectrum. We show that the method can be used as a design procedure for N-band antireflection coatings. Examples confirming the effectiveness of our procedure in designing dual- and three-band antireflection coatings are illustrated.

It is shown how the discussion about antireflection coatings for the visible and near infrared region has been changed dramatically with recent experimental applications of nanostructures that realize media with effective refractive indices less than the 'magic border' of 1.34. Using the so-called binary optics as an example, a glass-like nanostructure similar to the moth-eye structure is theoretically designed as antireflection coating for the visible and near infrared region. With the aim of this example and considering only known design principles of thin-film optics, a connection between nanostructures and thin films regarding their alternative or combined application as antireflection coatings is presented. As summary regarding the nanostructures vs. thin film discussion, a reference list is presented that cited different types of antireflection coatings presented in the past 70 years with respect to their applications, designs, and deposition technologies.

Silicon-containing antireflection coating (SiARC) and spin-on carbon (SOC) under-layers have been widely implemented for advanced semiconductor manufacturing since the 45 nm node. The combination of SiARC and SOC promises a superior solution for reflection control and a high etch selectivity. With the industry marching towards 22 nm and beyond, the tri-layer materials and processes are being finely tuned to meet the requirements. We report comprehensive evaluation results of the SiARC (with high silicon content) and carbon under-layer from manufacturing perspective. It focuses on the performances that are required to extend the tri-layer applications from the original 45 nm nodes to 22 nm and beyond, such as thickness selection, etch selectivity, resist compatibility, rework capability, and under-layer pattern wiggling issues.

The studies of undoped and p porous silicon -doped type micro and macro porous silicon (PS) prepared by chemical and electro-chemical etching are reported here. The optical reflectance and photoluminescence of samples obtained under different conditions have been investigated. The PS investigated samples exhibited photoluminescence (PL) and antireflection properties (ARS).© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The driving force behind combining the nanoimprinting and photolithography is to effectively utilize the advantages of both patterning techniques simultaneously. Conventional shadow-mask UV-lithography can be used to pattern micron-scale structures uniformly over large areas, whereas nanoimprinting enables patterning of nanoscale features, which can also be tilted or round-shaped. We present the work on direct patterning of micro-optical structures by combined nanoimprinting and lithography using modified mask aligner, hybrid mask mold and directly patternable, UV-curable materials. Patterning of structures is carried out in wafer-level fashion. Hybrid mask mold fabrication can be realized for example by modifying conventional shadow-mask using focused ion beam (FIB) milling, or by patterning a mold area on shadow-mask surface by nanoimprinting. One of the advantages of proposed fabrication method is that there is no need for reactive ion etching (RIE) process steps. We present also near-field holography (NFH) as a method of grating mold fabrication. Fabricated micro-optical structures include directly patterned waveguides with light coupling gratings, and also pyramid-shaped gratings which show antireflection properties in the mid-infrared spectral region.

New bottom anti-reflective coatings (BARCs) have been developed that can be incorporated into multiple patterning schemes utilizing scanner-track-only processes. The BARCs have modifiable optical properties and can be removed during the resist development step. Several dual patterning schemes were investigated for trench printing. The most promising process produced 110 nm trenches with approximately 1:1 space ratios. The etch characteristics of these BARCs under fluorinated and oxygenated gases were determined.

A novel approach to developer-soluble bottom anti-reflective coatings (BARCs) for 248-nm lithography was demonstrated. The BARC formulations are photosensitive, dye-filled systems incorporated with a polymer binder. The films are generated by thermally crosslinking the polymer matrix, and are then photochemically decrosslinked in order to render them soluble in developer solutions. The BARCs are compatible with solvents commonly used in the industry. Easy modification of the films with regard to optical properties for potential use with various substrates was also demonstrated. The BARCs exhibit anisotropic development in aqueous tetramethylammonium hydroxide (TMAH) solutions subsequent to simulated photoresist application, exposure, and post-exposure bake.

Reflectance spectrum calculations of double- and triple-layer antireflection coatings based on porous silicon layer are performed using the optical matrix approach method. Obtained results are compared with the reflectance spectrum of the SiO 2 /TiO 2 double-layer antireflection coating. A low reflectance value of both double- and triple-layer antireflection coatings made of porous silicon is observed in comparison to that SiO 2 /TiO 2 antireflection coating. These results are of importance for solar cells application.

A two-layer bottom anti-reflective coating (BARC) concept in which a layer that develops slowly is coated on top of a bottom layer that develops more rapidly was demonstrated. Development rate control was achieved by selection of crosslinker amount and BARC curing conditions. A single-layer BARC was compared with the two-layer BARC concept. The single-layer BARC does not clear out of 200-nm deep vias. When the slower developing single-layer BARC was coated on top of the faster developing layer, the vias were cleared. Lithographic evaluation of the two-layer BARC concept shows the same resolution advantages as the single-layer system. Planarization properties of a two-layer BARC system are better than for a single-layer system, when comparing the same total nominal thicknesses.

Deep ultraviolet (DUV) bottom anti-reflective coating (BARC)- to-resist compatibility is a key component in process optimization. In addition to the reduction of optical interference effects, BARC's also improve CD uniformity by preventing substrate contamination. However, if the BARC is not compatible with the resist, it can create adverse affects. If the acidity level of the BARC is not tuned to the resist for example, the profiles will foot or undercut, or if the BARC-to-resist developer interactions are not considered, high levels of post-develop defects will most likely occur. Etch selectivity, topography conformality and bowl/drain compatibility are other factors to consider when selecting a BARC. This paper follows the progressions of the leading DUV BARC's for Acetal-based resist systems and addresses the problems that could be encountered with implementing a BARC process. From DUV32 to the topography-conforming DUV42 and finally to the profile-enhancing DUV44, the 248 nm BARC's are continually evolving to resolve the BARC-to-resist compatibility issues.

REOSC has developed a new hard multispectral coating on ZnS compatible with military environment conditions. In extreme conditions the coating exhibit a pretty good behavior. Developed on ZnS, other substrates can be used. The coating itself can be tuned from UV up to 10micrometers . High transmission in visible spectrum >= 90 percent is achievable for an antireflection coating tuned around 8-10 micrometers on ZnS. The coating is laser compatible.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Costich's concept of intersection admittance for s- and p-polarization components of reflectivity of symmetrical three-layer subsystems together with depolarization of the incident medium and the substrate is used to design nonpolarizing narrow band anti-reflection coating. First, incident medium with one layer sub-coating and the substrate with three-layer sub- coating which forms a nonpolarizing structure of defined depolarized effective admittances are discussed. Next, the group of three layers was found which operates as depolarized system with effective admittance which match effective admittances of incident medium and the substrates are discussed. Superimposing of all these subsystems arrive at the design of the seven layer narrow band nonpolarizing anti-reflection coating. Ohmer's algorithm in generalized form by Knittl and Houserkova was used for finding the structure of the matching subsystem. Results of calculations are shown in graphical forms using conjugate s- and p- admittance diagrams.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A new, very simple AR coating synthesis method is further developed and compared to a recent `quasi-optimal' technique. A remarkable resemblance is found in the results. The reason for this similarity is given and the performance of both approaches is discussed.

In this article we discuss the questions of technology of antireflection coating for acousto-optic cells with oxide films.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

An eight-layer antireflection coating design including a buffer layer meets the specifications set for the coating design problem at the International Symposium on Optical Systems Design, Berlin, Germany, September 1992.

All contributed solutions to the coating design problem, sent out with the Advanced Program, are presented and evaluated.

Current estimates of the percentage of anti-reflection coated lenses verses uncoated in the market today range from 3% in the United States (US.), to 60% in Europe, to 80% in Japan. Currently upwards of 80% of all prescription eyewear lenses dispensed are resin. Glass lenses lose market share yearly, as scratch resistant coatings on resin lenses are improved. Photochromic resin materials are also improving and will shortly equal the performance of glass photockromics. Until recently, the performance characteristics of ophthalmic lenses were divided into two schools. In Europe, the emphasis was on keeping the reflections to an absolute minimum, while in the Asian market the emphasis was on producing a lens, which had exceptional scratch resistance. A typical European lens may average .4% reflection across the visible spectrum (400 to 700 urn.), while the Asian lenses averaged in the 1.5% range. The growth ofAR coating in the U.S. 80 million pair a year total ophthalmic market has been lagging foreign markets for several reasons.

Antireflecting coatings are widely used in ophthalmic fields because they increase transmission and cosmetic properties of spectacle lenses. Adhesion and hardness are very important to ensure time durability of the coating. We improved these properties on plastic (CR39) lenses using IAD technique on large-scale production plant.

A broadband antireflection coating on BK 7 was used to investigate the influence of dif-ferent optical monitoring strategies on the reproducibility of the completed layer system. The coating design consisted of 6 alternating layers of MgF 2 and TiO 2 of which 4 layers had optical thicknesses less than a quarterwave. Two different monitoring strategies were tes-ted: single test slide monitoring (all layers on one test slide) and monitoring of each layer on a separate test slide. Each strategy was tested by performing 10 production runs in a completely automated coating system equipped with a monochromatic photometer. The single test slide method proved to be more reproducible for the production of this specific layer system.