The structures add a phase element to masks which would usually just provide binary amplitude information. The normalized pressure sensitivity of a typical singlemode fused silica fiber coated with nylon is p 3. Jul 01, 2002 a alternating phase shift mask designed b mask features after laser scanning lithography, and the area deviation of the mask is 3. Pdf split of phase shifts in a phase mask for fiber bragg. Ep0810474b1 pattern exposing method using phase shift and. Phase shift masks are photomasks that take advantage of the interference generated by phase differences to improve image resolution in photolithography. The attenuated phase shift mask of claim 1 wherein said desired phase shift is 180. Where the light hits the wafer, the photoresist is exposed, and those areas are later removed in the. Qualitative comparison of image formed using transmission mask and phase shift mask.
The characterizations of these materials target the requirements of an euvl mask. Hariharan, in basics of interferometry, 1992 problem. Alternating phaseshift mask altpsm binary masks a binary photomask is composed of quartz and chrome features. In this scheme during every bit duration, denoted by t, one of two phases of the carrier is transmitted. Pattern exposing method using phase shift and mask used therefore download pdf info. An example of phase conflicting mask designed via our algorithm is shown to outperform a simple intuitive design. Light passes through the clear quartz areas and is blocked by the opaque chrome areas. While alternating phase shift masks are a stronger form of resolution enhancement than attenuated phase shift masks, their use has more complex consequences. New graph bipartizations for doubleexposure, bright field alternating phaseshift mask layout authors.
Method for phase shift mask design, fabrication, and use, us patent 6,800,401, date of. Phase shifting pupil filtering multiple exposure enhanced resists conventional annular quadru pole mask phase 0. Increases mask cost binary mask attenuating phase shift mask alternating. The optical properties of phase shift candidates were determined from 186 to 800 nm by spectroscopic ellipsometry and uvvisible spectroscopy. Phase shift mask techniques mask structure amplitude at mask intensity on wafer mask structure amplitude at mask intensity on wafer efield efield sidelobe alternating phase mask levenson attenuated phase mask. The attenuated phase shift mask of claim 3 wherein said first layer consists essentially of chromium and has a thickness within the range of about 25 to 75 nm for an incident wavelength of 365 nm. A phaseshift mask relies on the fact that light passing through a transparent media will undergo a phase change as a function of its optical thickness.
The mask shadowing effect is a unique phenomenon caused by a mirrorbased mask structure and an oblique incident angle of light in the. Optimisation of rim phase shift masks for contact holes. The scattering of light at the absorber edges results in significant phase deformations, which impact the effective phase and the lithographic performance of attpsm for euv. Us5532089a simplified fabrication methods for rim phase. Pdf polarized transmittancereflectance scatterometry. Designing phase shift mask structures using simphad. The idea of using phase shifting masks in optical lithography is among such resolutionenhancing techniques and is commonly. A mask pattern of lines and spaces of pitch p has an idealized amplitude transmittance function mx that produces a diffraction pattern mf x where f x is the spatial frequency. Pdf modeling mask scattered field at oblique incidence. Xray phaseshift mask for proximity xray lithography with. The phase shift mask technique, introduced in the beginning of the eighties, employs a transparent thin film that modulates the phase of the transmitted light in order to compensate the diffraction effect of the edges of the mask features 14. Oct 12, 2020 however, as wafer design shrinks, conventional 6% phase shift mask psm becomes unable to sufficiently meet the lithography requirements for dense dot pattern compared to dense line pattern. Pdf characterization of binary and attenuated phase shift. The extent that the transmission of an attenuating phase shift mask impacts the critical dimension cd control, however, has yet to be demonstrated.
This example indicates that a fairly general design procedure consisting of alternating phase shifts and our optimized phase shift mask is a viable candidate for future phase shifting mask design. Phaseshift lithography for subwavelength patterns of. Phase shift mask technology is required to extend the resolution range. These data were combined with optical modeling14 to determine the materials optical constants15 nik, from which phase shift mask designs could be calculated for duv and 193 nm.
When there is a horizontal poly interconnection, phase shift mask needs to be placed on the poly interconnect, and we improve vards to place phase shift mask in that way. Masks, vacuum and thin film, ihs publishing group, 1421, september 1999. Attenuated phase shift mask for extreme ultraviolet. Introduction as lithography moves towards the sub0. Pdf simulation and fabrication of attenuated phaseshifting. In the right example, phase shift mask can not be applied. Leaks or transmits 6% 180o phase light weak shift at edge. Abstractthe phaseshifting mask consists of a normal transmission mask that has been coated with a transparent layer patterned to ensure that the optical.
Sidewall profile inclination modulation mask spimm. Diffractive phaseshift lithography photomask operating in. One of two regions of the substrate along both sidewalls of a trace of the pattern has a recess such that phases of exposure light passing through the two regions are 180 inverse to each other. Attenuating embedded phase shifter, tisinitride chemistry, 193 nm lithography 1. Dwsk the home of phase shift, the best music game for pc. Pdf experiments to print 140 nm lines and 140 nm contact holes were optimized through simulation on an 18% transmitting phase shift mask for krf. Ep1286217b1 phase shift mask blanks, their manufacture and. Scaa, asymmetric lateral biased, additive, undercut, dual trench with and. Transmission mask phase shifting mask amplitude at mask amplitude at mask intensity at wafer intensity at wafer figure 1 1. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed. Development of phase shift lithography for the production. The proportion of masks within a mask set that incorporate opc and phase shift technology is rising as the minimum ic feature sizes continue to shrink 3, 9. The refractive index of ruta and ptmo alloys exhibits a large difference to that of air and provides the required phased shift of attenuated phase shift masks 2.
Arf transmittance attenuated phase shift mask is thick to need enough etching process condition. Phase shift mask measurements with excimer lasers205. Mask cost and profitability in photomask manufacturing. A binary chrome on glass mask is shown in a, and an alternating phase shift mask is shown in b. The use of phase shift mask increased the dof or process latitude of the printed contacts from 0. Liu and zakhor 18 formulated the mask design problem as the minimization of the l2 norm of the di erence between the ideal and the actual wafer images, and employed branchandbound and simulated annealing algorithms to synthesize binary and phase shift. In this paper, we will report the blank and mask properties for this high reflective phase shift type absorber material. By using an alternating aperture phase shift photomask aapsm, a resolution of 1. Google has not performed a legal analysis and makes no representation. When the upper and lower apertures impose on the transmitted beam a 180 phase shift relative to the middle aperture, the mask is an alternatingaperture psm. Extension of this technique to wavelengths as short as 157 nm is currently being undertaken.
Euv phase shift mask requirements for imaging at lowk1. Microelectronic engineering micro and nanoengineering. Polarized transmittancereflectance scatterometry measurements of 2d trench dimensions on phase shift masks john c. Carcia and others published thin films for phase shift masks find, read and cite all the research you need on researchgate. Jan 01, 1994 microelectronic engineering 23 1994 147150 elsevier optimisation of rim phase shift masks for contact holes z. A method for correcting characteristics of an attenuated phase shift mask having an attenuated layer including a storing a data in a memory, which shows a correlation between characteristics and process conditions, b measuring the characteristics of the attenuated phase shift mask, c calculating a appropriate process condition from the result of the step b and the data stored in the. Pdf imaging study of positive and negative tone weak. Ep1286217b1 phase shift mask blanks, their manufacture. To meet optical density, thicker cr layer is needed because mosi layer has high transmittance in 22% htpsm mask. Us6800214b2 method for correcting characteristics of. There exist alternating and attenuated phase shift masks. Multiple pitch transmission and phase analysis of six types of strong.
Comparative study of binary intensity mask and attenuated phase shift mask using hyperna immersion lithography e advanced lithogr for sub45nm era taeseung eom, juntaek park, sarohan park, sunyoung koo, jinsoo kim, byoung hoon lee chang moon lim hyeongsoo kim semiconductor spi hynix semiconductor inc. The phase shifting mask includes square patterns forming first and second light transmission areas disposed alternately. Besides the alternating phase shift regions shown above, phaseshift regions can be placed at the rim of larger structures to enhance the contrast of their image. The attenuated phaseshift mask shows improvement over a binary mask for. By simultaneously enhancing resolution and depth of. Pdf simulation and fabrication of attenuated phase. Aug 11, 2018 we explore the potential of attenuated phase shift mask attpsm to mitigate 3d mask effects and exploit them for future euv imaging. Us6723477b2 method for manufacturing phase shift mask blank. A simplified method of forming a phase shift structure for a lithographic mask includes the conformal deposition of a phase shift material, preferably having an index of refraction similar to that of the mask substrate, over a patterned layer of opaque material and exposed areas of the mask substrate corresponding to the pattern. Simulation and optimization of phase shift masks for printing of contact holes. Continuous phaseshift lithography with a rolltype mask. Figure 4 compares the working of an alternatetype psm with a conventional binary mask. New graph bipartizations for doubleexposure, bright field. Phaseshift mask issues for 193 nm lithography citeseerx.
Pdf imaging study of positive and negative tone weak phase. Phase wrapping in the phase shifting method is the process of determining the phase values of the fringe patterns in the range of 0 to 2 rors in. The trace has different thicknesses on its sides adjacent to the two. Such features can be accommodated in the process flow for fabricating phase shift masks by the definition of one or two extra layers of processing in the mask shop. The attenuated psm image has a sharper transition at the mask edge, resulting. Generally, there are layout patterns that phase shift mask can not apply, and hence we must. Tisinitride attenuating phaseshift photomask for 193 nm.
The aerial image simulated with the ideal alt psm feature has 9. Attenuated phase shift mask advanced micro devices, inc. The phase shift mask i technique has shown a lot of promise in extending the resolu tion of optical lithography to the next generation of vlsi manufacturing. For example, the alternating phaseshift mask technique is being used by intel to print gates for their 65 nm and subsequent node transistors. While alternating aperture psms are important, the overwhelming majority of phase shift masks used today are attenuated psms also called embedded phase shift masks, epsm. Binary and phase shifting mask design for optical lithography. This example indicates that a fairly general design procedure consisting of alternating phase shifts and our optimized phase shift mask is a viable candidate for future phase shifting mask. For 45 nm node and beyond, the alternating phase shift mask alt. Us5411824a phase shifting mask structure with absorbing. Materials screening for attenuating embedded phaseshift. We demonstrate a new type of spatial phase shifting, dynamic interferometer that can acquire phase shifted interferograms in a single camera frame. In gate line printing, the use of alternating phase shift mask for improved depth of focus and for improved cd control has been demonstrated 12. Unlike many other phase shifting masks, they can be used for any arbitrary mask pattern.
Jinglei du, zheng cui, xiaocong yuan, yongkang guo. The smallest phase shift that can be measured in a fiber interferometer used for pressure sensing is 1. The authors propose a number of predistorted mask design techniques for binary and phase shifting masks. Method for phase shift mask design, fabrication, and use, us patent 6,800,401, date of patent october 5, 2004. As a result, a transparent conductor with suitable properties was achieved with a recently built cylindrical phase shift lithography prototype designed to pattern on 100 mm2 of substrate area. Aci phase shift mask, using a spectrophotometerbased instrument, capable of collecting four continuous spectra during one measurement two polarized reflectance spectra rs and rp and two polarized transmittance spectra ts and. A phase shifting mask includes a transparent substrate and a pattern formed of a translucent film on the transparent substrate. The interferometer is constructed with a pixelated phase mask aligned to a detector array.
These structures are typically much larger in size than device nominal, and this method may be applied to either one axis or both axes of the kerf. Thin films for phaseshift masks 1 optical lithography. The concept is quite simple and is illustrated in figure 1lb. European patent office prior art keywords phase shift pattern reticle resist layer prior art date 19910927 legal status the legal status is an assumption and is not a legal conclusion.
As a result, a transparent conductor with suitable properties was achieved with a recently built cylindrical phase shift lithography prototype designed to. Alternating phase shifted masks are a powerful ret which can effectively double the resolution of a conventional optical lithography system. In this study, we have investigated the absorption and the phase shift controllability of xray masks with various absorber materials by simulation and found that the phase shift mask structure with cu absorber is one of the best choices for proximity xray lithography using synchrotron radiation. Ep0810474b1 pattern exposing method using phase shift. Introduction a s the minimum feature size in vlsi circuits drops into submicron region, distortions due to optical dif fraction can no longer be neglected. The attenuating embedded phase shift aps mask1,2,3. Typically mosi2 with a 68% transmission at a thickness that causes a 180o phase shift. Gec plessey semiconductors, tamerton road, roborough, plymouth, devon pl6 7bq, u. Phase shift mask a phase shift mask psm utilizes not only the light intensity distribution used in conventional masks but also the optical phase. Investigation of phase shift mask distortion effect.
Development of high reflective phase shift type absorber for. The preferred method is particularly applicable for use generating phase shift mask designs from vlsi cad datasets. One of the promising candidates is attenuated phase shirt type absorber which is effective for specific pattern shape such as contact hole. Phase shift masks psm consist of treating the mask as a threedimensional structure and in ducing phase shift in the transmitted electric eld such that it causes favorable constructive and destructive interference in the desired bright and dark areas respectively 39, 18, 34. Phase shifted masks psms promise significant performance benefits for conventional optical lithography. Citeseerx binary and phase shift mask design for optical. Binary and phase shifting mask design for optical lithography ieee. The idea of incorporating psms in photolithography was first pioneered in the early 1980s. Simulation and optimization of phaseshift masks for printing of. Prior art keywords phase shift film shift mask mask blank layers prior art date 20010626 legal status the legal status is an assumption and is not a legal conclusion. Several ret such as opc optical proximity correction, psm phase.
Lithography for 100 nm and beyond uc berkeley stanford mit vacuum ultraviolet transmission cutoffs of available optical. Characterization of binary and attenuated phase shift mask. Automatic generation of standard cell library in vdsm. Phaseshifting techniques for laser direct write systems. Us6207333b1 mask with attenuating phaseshift and opaque. Comparative study of binary intensity mask and attenuated. A method of utilizing aims to quantify lithographic. Pdf resolution enhancement with hightransmission attenuating. Phase shift mask making by ebeam lithography sciencedirect. An attenuated phase shift mask comprising a first layer having a thickness to provide a transmission in the range of about 3 to 10% formed on a transparent substrate and a second layer comprising a transparent material having a thickness to provide a.
A phase shifting mask has phase shifters in which the sidewalls of the shifters are coated with a light absorbing or. Work in 12 describes the production of feature sizes in the region of 90 nm using an elastomeric phase mask and incoherent, polychromatic ultraviolet light. Martin central microstructure facility, rutherford appleton laboratory, chilton, didcot, oxon ox11 oqx, u. Continuous phaseshift lithography with a rolltype mask and. Us6326107b1 phase shift mask and process for manufacturing. The impact of phase errors on phase shifting masks, part 3. Because of the thicker cr layer, source power and chlorine gas composition ratio of dry etch process was adjusted and optimized. Improved imaging properties of thin attenuated phase shift masks for. Improving resolution in photolithography with a phaseshifting mask. Us5487963a phase shifting mask wherein light transmitted. A pixelbased regularization approach to inverse lithography. Us6066180a automatic generation of phase shift masks using net.
The thickness of the opaque patterned layer, in combination with. A method of fabricating an attenuating phase shift photolithographic mask which will reduce the formation of sidelobes adjacent to large structures in the kerf regions on the patterned wafer. An integrated imaging system for the 45nm technology node contact holes using polarized off axis illumination, immersion, weak phase shift masks and negative resists, proc. To provide a method for manufacturing a phase shift mask blank hating a light translucent film or a light translucent portion having the designated phase angle and transmittance and being superior in film characteristics of chemical resistance, light resistance, and internal stress. Depth of focus and the alternating phase shift mask. Attenuated phaseshifting mask spie digital library. Test pattern, background transmission is clear, attenuated phase shift mask psm respectively. These sloped sidewalls are defined by attenuated phase shift mask attpsm features which impart phase shifts other than 180 or 0 degrees. Hahmann jenoptik gmbh, system technology division, carlzeissstrasse 1, 06900 jena, frg abstract a procedure is described to expose phase shift masks with high accuracy.
Apr 01, 1993 microelectronic engineering 21 1993 169172 elsevier 169 phase shift mask making by ebeam lithography h. However, as wafer design shrinks, conventional 6% phase shift mask psm becomes unable to sufficiently meet the lithography requirements for dense dot pattern compared to dense line pattern. Pattern exposing method using phase shift and mask used therefore download pdf info publication number ep0810474b1. Attenuated phase shifting masks att psms use a slightly transmissive absorber with a.
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