X-ray lithography

X-ray lithography is a process used in semiconductor device fabrication industry to selectively remove parts of a thin film of photoresist. It uses X-rays to transfer a geometric pattern from a mask to a light-sensitive chemical photoresist, or simply "resist," on the substrate to reach extremely small topological size of a feature. A series of chemical treatments then engraves the produced pattern into the material underneath the photoresist.

It's less commonly used in commercial production due to prohibitively high costs of materials (such as gold used for X-rays blocking) etc.[1]

Mechanisms

X-ray lithography originated as a candidate for next-generation lithography for the semiconductor industry[1], with batches of microprocessors successfully produced. Having short wavelengths (below 1 nm), X-rays overcome the diffraction limits of optical lithography, allowing smaller feature sizes. If the X-ray source isn't collimated, as with a synchrotron radiation, elementary collimating mirrors or diffractive lenses are used in the place of the refractive lenses used in optics. The X-rays illuminate a mask placed in proximity of a resist-coated wafer. The X-rays are broadband, typically from a compact synchrotron radiation source, allowing rapid exposure. Deep X-ray lithography (DXRL) uses yet shorter wavelengths on the order of 0.1 nm and modified procedures such as the LIGA process, to fabricate deep and even three-dimensional structures.

The mask consists of an X-ray absorber, typically of gold or compounds of tantalum or tungsten, on a membrane that is transparent to X-rays, typically of silicon carbide or diamond. The pattern on the mask is written by direct-write electron beam lithography onto a resist that is developed by conventional semiconductor processes. The membrane can be stretched for overlay accuracy.

Most X-ray lithography demonstrations have been performed by copying with image fidelity (without magnification) on the line of fuzzy contrast as illustrated in the figure. However, with the increasing need for high resolution, X-ray lithography is now performed on what is called the "sweet spot", using local "demagnification by bias".[2][3] Dense structures are developed by multiple exposures with translation. The advantages of using 3x demagnification include, the mask is more easily fabricated, the mask to wafer gap is increased, and the contrast is higher. The technique is extensible to dense 15 nm prints.

X-rays generate secondary electrons as in the cases of extreme ultraviolet lithography and electron beam lithography. While the fine pattern definition is due principally to secondaries from Auger electrons with a short path length, the primary electrons will sensitize the resist over a larger region than the X-ray exposure. While this does not affect the pattern pitch resolution, which is determined by wavelength and gap, the image exposure contrast (max-min)/(max+min) is reduced because the pitch is on the order of the primary photo-electron range. The sidewall roughness and slopes are influenced by these secondary electrons as they can travel few micrometers in the area under the absorber, depending on exposure X-ray energy.[4] Several prints at about 30 nm have been published.[5]

Another manifestation of the photoelectron effect is exposure to X-ray generated electrons from thick gold films used for making daughter masks.[6] Simulations suggest that photoelectron generation from the gold substrate may affect dissolution rates.

Photoelectrons, secondary electrons and Auger electrons

Secondary electrons have energies of 25 eV or less, and can be generated by any ionizing radiation (VUV, EUV, X-rays, ions and other electrons). Auger electrons have energies of hundreds of electronvolts. The secondaries (generated by and outnumbering the Auger and primary photoelectrons) are the main agents for resist exposure.[citation needed]

The relative ranges of photoelectron primaries and Auger electrons depend on their respective energies. These energies depend on the energy of incident radiation and on the composition of the resist. There is considerable room for optimum selection (reference 3 of the article). When Auger electrons have lower energies than primary photoelectrons, they have shorter ranges. Both decay to secondaries which interact with chemical bonds.[7] When secondary energies are too low, they fail to break the chemical bonds and cease to affect print resolution. Experiments prove that the combined range is less than 20 nm. On the other hand, the secondaries follow a different trend below ≈30 eV: the lower the energy, the longer the mean free path though they are not then able to affect resist development.[citation needed]

As they decay, primary photo-electrons and Auger electrons eventually become physically indistinguishable (as in Fermi–Dirac statistics) from secondary electrons. The range of low-energy secondary electrons is sometimes larger than the range of primary photo-electrons or of Auger electrons. What matters for X-ray lithography is the effective range of electrons that have sufficient energy to make or break chemical bonds in negative or positive resists.[citation needed]

Lithographic electron range

X-rays do not charge. The relatively large mean free path (~20 nm) of secondary electrons hinders resolution control at nanometer scale. In particular, electron beam lithography suffers negative charging by incident electrons and consequent beam spread which limits resolution. It is difficult therefore to isolate the effective range of secondaries which may be less than 1 nm.

The combined electron mean free path results in an image blur, which is usually modeled as a Gaussian function (where σ = blur) that is convolved with the expected image. As the desired resolution approaches the blur, the dose image becomes broader than the aerial image of the incident X-rays. The blur that matters is the latent image that describes the making or breaking of bonds during the exposure of resist. The developed image is the final relief image produced by the selected high contrast development process on the latent image.

The range of primary, Auger, secondary and ultralow energy higher-order generation electrons which print (as STM studies proved) can be large (tens of nm) or small (nm), according to various cited publications. Because this range is not a fixed number, it is hard to quantify. Line edge roughness is aggravated by the associated uncertainty. Line edge roughness is supposedly statistical in origin and only indirectly dependent on mean range. Under commonly practiced lithography conditions, the various electron ranges can be controlled and utilized.

Charging

X-rays carry no charge, but at the energies involved, Auger decay of ionized species in a specimen is more probable than radiative decay. High-energy radiation exceeding the ionization potential also generates free electrons which are negligible compared to those produced by electron beams which are charged. Charging of the sample following ionization is an extremely weak possibility when it cannot be guaranteed the ionized electrons leaving the surface or remaining in the sample are adequately balanced from other sources in time. The energy transfer to electrons as a result of ionizing radiation results in separated positive and negative charges which quickly recombine due partly to the long range of the Coulomb force. Insulating films like gate oxides and resists have been observed to charge to a positive or negative potential under electron-beam irradiation. Insulating films are eventually neutralized locally by space charge (electrons entering and exiting the surface) at the resist-vacuum interface and Fowler-Nordheim injection from the substrate.[8] The range of the electrons in the film can be affected by the local electric field. The situation is complicated by the presence of holes (positively charged electron vacancies) which are generated along with the secondary electrons, and which may be expected to follow them around. As neutralization proceeds, any initial charge concentration effectively starts to spread out. The final chemical state of the film is reached after neutralization is completed, after all the electrons have eventually slowed down. Usually, excepting X-ray steppers, charging can be further controlled by flood gun or resist thickness or charge dissipation layer.

See also

Notes

  1. ^ Y. Vladimirsky, "Lithography" in Vacuum Ultraviolet Spectroscopy II Eds. J.A.Samson and D.L.Ederer, Ch 10 pp 205–223, Academic Press (1998).
  2. ^ Vladimirsky, Yuli; Bourdillon, Antony; Vladimirsky, Olga; Jiang, Wenlong; Leonard, Quinn (1999). "Demagnification in proximity x-ray lithography and extensibility to 25 nm by optimizing Fresnel diffraction". Journal of Physics D: Applied Physics. 32 (22): 114. Bibcode:1999JPhD...32..114V. doi:10.1088/0022-3727/32/22/102.
  3. ^ Antony Bourdillon and Yuli Vladimirsky, X-ray Lithography on the Sweet Spot, UHRL, San Jose, (2006) ISBN 978-0-9789839-0-1
  4. ^ Vora, K D; Shew, B Y; Harvey, E C; Hayes, J P; Peele, A G (2008). "Sidewall slopes of SU-8 HARMST using deep x-ray lithography". Journal of Micromechanics and Microengineering. 18 (3): 035037. Bibcode:2008JMiMi..18c5037V. doi:10.1088/0960-1317/18/3/035037.
  5. ^ Early, K; Schattenburg, M; Smith, H (1990). "Absence of resolution degradation in X-ray lithography for λ from 4.5nm to 0.83nm". Microelectronic Engineering. 11: 317. doi:10.1016/0167-9317(90)90122-A.
  6. ^ Carter, D. J. D. (1997). "Direct measurement of the effect of substrate photoelectrons in x-ray nanolithography". Journal of Vacuum Science and Technology B. 15 (6): 2509. Bibcode:1997JVSTB..15.2509C. doi:10.1116/1.589675.
  7. ^ Lud, Simon Q.; Steenackers, Marin; Jordan, Rainer; Bruno, Paola; Gruen, Dieter M.; Feulner, Peter; Garrido, Jose A.; Stutzmann, Martin (2006). "Chemical Grafting of Biphenyl Self-Assembled Monolayers on Ultrananocrystalline Diamond". Journal of the American Chemical Society. 128 (51): 16884–91. doi:10.1021/ja0657049. PMID 17177439.
  8. ^ Glavatskikh, I. A.; Kortov, V. S.; Fitting, H.-J. (2001). "Self-consistent electrical charging of insulating layers and metal-insulator-semiconductor structures". Journal of Applied Physics. 89: 440. Bibcode:2001JAP....89..440G. doi:10.1063/1.1330242.


References

  1. ^ "Pdf - Semiconductor Technology from A to Z - Halbleiter.org". www.halbleiter.org. Retrieved 2022-06-14.

Read other articles:

Halaman ini berisi artikel tentang sebuah organisasi massa di Indonesia. Untuk partai politik yang memiliki nama yang sama dengan singkatannya, lihat Partai Nasional Demokrat (2011). Nasional DemokratSingkatanNasDemTanggal pendirian1 Februari 2010; 13 tahun lalu (2010-02-01)TipeOrganisasi massaKantor pusatJl. R.P. Soeroso No. 46, Gondangdia Lama, Menteng, Jakarta Pusat, Jakarta 10350Ketua umumSurya PalohSekretaris jenderalSyamsul Mu'arifSitus webwww.ormasnasdem.org Nasional Demokrat (dis...

 

MidnightPoster rilis layar lebarSutradara Mitchell Leisen Produser Arthur Hornblow Jr. Ditulis oleh Charles Brackett Billy Wilder Skenario Charles Brackett Billy Wilder Cerita Edwin Justus Mayer Franz Schulz Pemeran Claudette Colbert Don Ameche John Barrymore Francis Lederer Mary Astor Elaine Barrie Penata musikFrederick HollanderSinematograferCharles LangPenyuntingDoane HarrisonPerusahaanproduksiParamount PicturesDistributorParamount PicturesTanggal rilis 15 Maret 1939 (1939-03-15...

 

Halaman ini berisi artikel tentang dewa mitologi Romawi. Untuk kegunaan lain, lihat Jupiter (disambiguasi). JupiterDewa langit dan petirAnggota Triad Arkais dan CapitolinaPatung marmer Jupiter dari ca. 100 M[a]Nama lainYoveDipuja oleh umatKultus kekaisaran RomawiAgama politeistisKediamanRomaSimbolHalilintar, elang, pohon ekInformasi pribadiYunoAnakMars, Vulkanus, Belona, YuventasOrang tuaSaturnus dan OpsSaudaraTradisi Romawi: Yuno, Seres, VestaYunani-Romawi: Pluto dan NeptunusYu...

Equation that does not involve powers or products of variables This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: Linear equation – news · newspapers · books · scholar · JSTOR (January 2016) (Learn how and when to remove this template message) Two graphs of linear equations in two variables In mathematics, a li...

 

Struth Gemeinde Rodeberg Koordinaten: 51° 13′ N, 10° 18′ O51.22310.304388888889476Koordinaten: 51° 13′ 23″ N, 10° 18′ 16″ O Höhe: 476 (460–490) m Einwohner: 1554 (31. Dez. 2022)[1] Eingemeindung: 30. Juni 1994 Postleitzahl: 99976 Vorwahl: 036026 Struth von Süden aus gesehen Struth ist ein Ortsteil der Gemeinde Rodeberg im (Süd-)Eichsfeld. Er liegt im Unstrut-Hainich-Kreis in Thüringen. Die...

 

Ця стаття є частиною Проєкту:Кінематограф (рівень: невідомий) Портал «Кінематограф»Мета проєкту — створення якісних та інформативних статей на теми, пов'язані з кінематографом. Ви можете покращити цю статтю, відредагувавши її, а на сторінці проєкту вказано, чим ще можна д

العلاقات الصينية الصربية الصين صربيا   الصين   صربيا تعديل مصدري - تعديل   العلاقات الصينية الصربية هي العلاقات الثنائية التي تجمع بين الصين وصربيا.[1][2][3][4][5] مقارنة بين البلدين هذه مقارنة عامة ومرجعية للدولتين: وجه المقارنة الصين صربيا المس

 

Non-governmental chamber of commerce in China All-China Federation of Industry and Commerce中华全国工商业联合会ACFIC headquartersAbbreviationACFICFormation1953FounderChen ShutongTypeBusiness associationLegal statusPeople's organizationLocationBeijing, ChinaMembership 4.71 millionKey peopleGao Yunlong(Chairman)Xu Lejiang(Executive Vice Chairman)Websitewww.chinachamber.org.cn (in English)www.acfic.org.cn (in Chinese) Politics of China Leadership Leadership generations Succession of po...

 

M6Diluncurkan1 Maret 1987 at 11:15 amPemilikM6 Group (51,2%) RTL Group (48,8%)Pangsa pemirsa11.0% (April 2008, [1])Negara Prancis  SwissSaluran seindukW96terGulliTévaParis PremièreTiJiCanal JM6 MusicSérie ClubSitus webwww.6play.fr/m6 Métropole 6, dikenal sebagai M6, merupakan sebuah layanan televisi Prancis yang dimiliki oleh perusahaan M6 Group. M6 menyiarkan sinyal SECAM di-atas-air, dan juga pada satelit siar Atlantic Bird 3. M6 juga menyiarkan sinyal digital ke Swiss me...

Artikel ini sebatang kara, artinya tidak ada artikel lain yang memiliki pranala balik ke halaman ini.Bantulah menambah pranala ke artikel ini dari artikel yang berhubungan atau coba peralatan pencari pranala.Tag ini diberikan pada Desember 2022. Pengeboman Bandar Udara Internasional Beijing 2013LokasiTerminal 3 Bandar Udara Internasional Beijing di Beijing, Tiongkok [1]Koordinat40°04′48″N 116°35′04″E / 40.08000°N 116.58444°E / 40.08000; 116.58444Tan...

 

Eurovision Song Contest 2010Country GermanyNational selectionSelection processUnser Star für OsloSelection date(s)Heats:2 February 20109 February 201016 February 201023 February 20102 March 2010Quarter-final:5 March 2010Semi-final:9 March 2010Final:12 March 2010Selected entrantLenaSelected songSatelliteSelected songwriter(s)Julie FrostJohn GordonFinals performanceFinal result1st, 246 pointsGermany in the Eurovision Song Contest ◄2009 • 2010 • 2011► ...

 

جزء من سلسلة مقالات حولديانة قدماء المصريين مفاهيم الحياة الآخرة دوات ماعت الأساطير الأرقام الفلسفة الروح طقوس الجنائزية القرابين المعابد الأهرامات الآلهةثامون هيرموبوليس (أجدود) آمون أمونيت حح ححيت كيك [الإنجليزية] كيكيت [الإنجليزية] نوو نوونيت تاسوع هليوبوليس أتوم جب ...

Tentara Virginia UtaraBendera Tentara Virginia Utara pada masa komando Robert E. Lee atau Bendera Markas Besar Robert E. LeeAktif22 Oktober 1861 – Kebanyakan unit dideaktifkan pada Januari–April 1862; tentara dibubarkan pada 12 April 1865Negara Negara KonfederasiCabang Tentara KonfederasiPeranTentara Konfederasi Primer di Teater TimurMarkasRichmond, VirginiaPertempuranPerang Saudara AmerikaTokohTokoh berjasaP. G. T. BeauregardJoseph E. JohnstonGustavus Woodson SmithRobert E. Lee...

 

Sigrid AgrenAgren pada pameran busana Zuhair MuradLahir24 April 1991 (umur 32)[1]Martinique, Prancis[1]Informasi modelingTinggi5 ft 93 in (3,89 m)[2]Warna rambutPirang[1]Warna mataCokelat Muda[1]ManajerThe Society Management New YorkElite Model Management[1] Sigrid Agren (lahir 24 April 1991[1]) adalah model busana Prancis asal Martinique yang memenangkan Elite Model Look tahun 2006.[3] Kehidupan awal Agren la...

 

Người giúp việc đang là quần áo Người giúp việc là những người được các gia đình hay cá nhân thuê làm các công việc nhà như nấu ăn, lau dọn, làm vườn hay thậm chí là chăm sóc trẻ em và người già, tùy theo yêu cầu của gia chủ. Một số người giúp việc gia đình sống trong hộ gia đình của người chủ sử dụng lao động. Trong một số trường hợp, sự đóng góp và kỹ năng của người g...

Signing the Mayflower Compact 1620, a painting by Jean Leon Gerome Ferris 1899 Christopher Martin (c. 1582–1621)[1] and his family embarked on the historic 1620 voyage of the Pilgrim ship Mayflower on its journey to the New World. He was initially the governor of passengers on the ship Speedwell until that ship was found to be unseaworthy, and later on the Mayflower, until replaced by John Carver. He was a signatory to the Mayflower Compact. He and his family all perished in the fir...

 

Los diamantes son eternos de Ian Fleming Género Novela de espionajeAmbientada en Guinea Francesa Idioma InglésTítulo original Diamonds Are ForeverEditorial Glidrose PublicationsPaís Reino UnidoReino UnidoFecha de publicación 26 de marzo de 1956Formato ImpresoJames BondMoonrakerLos diamantes son eternosDesde Rusia con amor [editar datos en Wikidata] Diamantes para la eternidad es la cuarta novela de la serie de James Bond de Ian Fleming. Fue publicada primeramente por Jonat...

 

Dieser Artikel ist nicht hinreichend mit Belegen (beispielsweise Einzelnachweisen) ausgestattet. Angaben ohne ausreichenden Beleg könnten demnächst entfernt werden. Bitte hilf Wikipedia, indem du die Angaben recherchierst und gute Belege einfügst. Haus mit der Gedenktafel, wo der Frieden von Swischtow unterzeichnet wurde Leopold II. Selim III. Der Frieden von Swischtow, veraltet und vor allem in Österreich als Frieden von Sistowa bekannt, war ein Friedensabkommen vom 4. August 1791, das d...

Quo VadisLillian Hall-Davis dalam Quo VadisSutradara Gabriellino D'Annunzio Georg Jacoby Produser Arturo Ambrosio Ditulis oleh Gabriellino D'Annunzio Georg Jacoby BerdasarkanQuo Vadisoleh Henryk SienkiewiczPemeranEmil Jannings Elena Sangro Lillian Hall-Davis Rina De LiguoroSinematograferCurt Courant Alfredo Donelli Giovanni VitrottiPerusahaanproduksiUnione Cinematografica ItalianaDistributorUnione Cinematografica Italiana (Italia) First National Pictures (Amerika Serikat)Tanggal rilis Oktober...

 

Puntik DalamDesaNegara IndonesiaProvinsiKalimantan SelatanKabupatenBarito KualaKecamatanMandastanaKode pos70581Kode Kemendagri63.04.06.2004 Luas... km²Jumlah penduduk... jiwaKepadatan... jiwa/km² Puntik Dalam adalah salah satu desa yang terletak di Kecamatan Mandastana, Kabupaten Barito Kuala, Provinsi Kalimantan Selatan, Indonesia. Pranala luar (Indonesia) Keputusan Menteri Dalam Negeri Nomor 050-145 Tahun 2022 tentang Pemberian dan Pemutakhiran Kode, Data Wilayah Administrasi Pemerin...

 

Strategi Solo vs Squad di Free Fire: Cara Menang Mudah!