DD215179A1 - CATADIOPRIC MICRORE PRODUCTION LENS FOR APPLICATION IN DEEP UV - Google Patents

Abstract

A catadioptric distortion-free, high resolution microresuction objective for the fabrication of submicron scale integrated circuits operating at a wavelength of 265 nm in the scale -0.5 <equal to beta <equal to -0.1 and having a maximum numerical aperture of 0.35. Through two dioptric assemblies and two mirrors, the light from the object plane is guided through the dioptric assemblies and over the mirrors so that, after beam splitting in a graduation cube, 50% of the incident light contributes to image formation.

Description

Title of the invention

Catadioptric Microreproduction Lens for ·. Application in deep UV

Field of application of the invention;

The invention relates to a distortion-free catadioptric microreaction lens of high resolution for use in the deep UY, which, in the micro-production technology in particular for the production of highly integrated circuits with structures in the submicron range in microelectronics is 'sets'. ,

Two principle solutions for the transfer of structure from the stencil to the wafer on the basis of the optical projection are known: the scanning and the progressive projection lithography.

As optical projection systems for scanning projection lithography, two-mirror systems (US Pat. No. 37 4B-015) and two-mirror systems with dioptric components (US Pat. No. 4,293,136) are used. These systems allow, due to the fact that only mirrors or mirrors are used in conjunction with synthetic quartz dioptric components, a structure transmission with a radiation in the range of deep UV at ca * 250 nm. All known optical arrangements for scanning pro jection lithography have numerical apertures below n ^f . sin u ^! = 0.19, higher numerical apertures are not achievable, since the known optical arrangements at higher numerical apertures have non-recoverable .Resüaberrationen that a diffraction-limited imaging,

  - 9 -

as is required for photolithography. - .. .. · ·

Lens lenses are known as optical projection systems for step-by-step projection lithography, in which the demand for the shortest possible wavelength for structure transmission is matched by the requirement for the highest possible trans mission. The 'optimal' compromise is 436 nm focal length ♦ At this wavelength Most photolithography lenses work. Occasionally, the structure transfer takes place with a centroid wavelength of 405 nm and, when restricted to very small image fields, 365 nm. For even shorter wavelengths, no lens objectives are known. '.- ..'. '' ..

In addition to high-aperture dioptric systems, single-mirror systems are also known in combination with high numerical aperture dioptric devices. These systems have all; a magnification β '= -1 or 13'. = -1 .., - 0, D. The low magnification is disadvantageous in the transmission of very small structures in the submicron range, because it requires extremely high demands on the quality of the stencils. Conventional glasses are generally used for the dioptric assemblies of the known systems In addition, the systems with a division cube according to "DB-GEI 6,944,528 have the disadvantage that - by using only one mirror, at most 25 % of that of the template outgoing radiation can be used to structure over transmission; and that by the 1: 1 image _: at the mirror with 'practically unavoidable residual errors in the centering of the: • individual assemblies by reflection on the stencil doubling structures in the image plane arise which make the system unusable for the practical structure transfer,

The in US Pat. 3,917,399 proposed; Suppression of the stray light by polarization-optical components requires such devices in a high-aperture system

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with high constancy of the polarization effect over a large range of incidence, whose technical control causes extreme difficulties.

For a given center of gravity wavelength, the requirement for transmission of ever smaller structures can only be realized by increasing the numerical aperture of the objectives. Due to the associated reduction in the depth of field exists a Grenzapertur beyond which no .Steigerung the usable smallest feature width under real. Conditions can be achieved. As the upper limit, a numerical aperture of η 'sin u' = 0.40 *. 0.45 is considered at X = 436 nm. The smallest usable feature width is 0.3 pn

-realized under laboratory conditions. '

Object of the invention

The aim of the invention is a distortion-free, catadioptric high resolution micro-reproduction objective for use in deep UV, which allows a transmission of structures up to 0.6 μm, - '· ·

Explanation of the essence of the invention

The invention has for its object to provide a distortion-free, catadioptric microreacessing lens with higher photolithographic resolution than hitherto known Reprcduktionsob jektive, the photolithographic depth of field and the image field size about those of the known projection lenses for exposure at 436 nm.mit a limit for the smallest usable structure around O, 3yum *. ,

The object is achieved by a catadioptric micro-reproduction objective for use in the low L ⁷ V, which has a magnification -0.5 $ β r -0,1, operates at a centroid wavelength of 265 nm and has a maximum numerical aperture of 0.35, according to the invention in that it has the following characteristic features,

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It consists of 2 ········· groups and two identical mirrors arranged on four sides of a semitransparent cube, with their four optical axes lying in one plane and piercing the four outer faces of the cube in the centroidal area. partially transparent layer represents a plane that extends from one edge of the cube to the other. diagonally opposite so runs that above and below this level each ein.Spiegel and a dioptric assembly are, dioptric assembly and mirrors' face each other, and object and image plane respectively on the side of the division cubes opposite a.,. Dioptric Assembly are located * ''

All dioptric components. And the partly elliptical cube are made of optical media with a transmission of ~ C pep> -0.8 for 100 mm glass path. Both dioptric assemblies are designed in such a way that the Petzval sum of both systems is that of the mirror largely compensated «

The. radiation emitted by the object: passes through the object. the two: light components, each reflected by a mirror, and half of the radiation, transmits, after passing through the image-sided-dioptric assembly Image Formulation "The entire assembly is made such that the light reflection reflected on the partially transmissive layer over the stencil extends only beyond Y5 of the field diameter." Thus, independent of the reflectivity of the template, at least 3 can be used for the structure transfer, in the case of the structure transfer to the wafer, the entire wafer can be used by a stepwise exposure according to FIG Compliance with the condition

S "

^^^^ reached, 7/0 at S the object

input cut-off, S 'is the object output cutoff and the radius of the mirror,

41 id.

Exemplary embodiment

The invention will be explained in more detail with reference to an embodiment shown in the drawing. Show it

Fig. 1 shows the schematic optical structure of the lens Fig. 2, the maximum extent of the reflected Palschlichtes.

Fig. 3 shows a reduced image field with too high Palschlichtanteil. Fig. 4 shows schematically the execution of the stepwise exposure on the wafer

The objective according to the invention has four optical axes in one plane, which are perpendicular to one another «

Starting from a point of the object plane OE, the light propagates along the one optical axis and passes through the dioptric components, a cemented element · L 1, L, 2, a double meniscus L 3, 14, a cemented element L 5, Ij 6, a scattering element L 7- and a cemented element L S, L 9, which are arranged in. The distances D.3, D o, D 9 and D 1 T-, and occurs in the distance D 14 in the division throw el T with the edge lengths; D 15 on. At the partially transmissive layer of the division cube T, the beam path is split into two parts which are perpendicular to one another in a plane, these being identical to two arranged at a distance D 16 in the direction of the optical axes. Reflect Sp 1 and Sp 2 reflected.

The reflected components of the light emitted by OE finally exit the division cube T after unification perpendicular to the sinusoidal direction, pass through two cement groups L 10. LH at a distance D 17 from the division cube T, L 12, 1 13 at a distance D 20 from L 10, L 11, a dissipative element L 14 at a distance D 23 from L 10, L 11, a cemented element L 15, L 16 at a distance D 23 from L 14 and generate in BE the image of the relevant point of the object plane.

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tabell e 1 65 thick rip 000 , ⁿ e. ' 1 , 43496 ^v e = 94, 66 Radii. 16 14 000 V ₅ , 46012 = 67, 16 D ₁ = 16 220. H ₁ = v " 66 R ₁ = 47 ; ^D 2 = 195, 000. n ₂ = r. , 46012 ^V 2 = 67, 56 R ₂ = 84 D = % 000 .1 . , 43496  = 94, Ό _ ^iU 3. "V = 60 j ^D 4 ^{: =} 380 ' ⁿ 4 ^{= V} 4 4 P 573.66 70 D = 293, 730 , i .e ₅ =  t; , 43496.: , ^y 5: = 94, 66 J Rr = -2363, .60 D, = 0 : 9, 100 1 , 46012 " = 67, OR ₇ = 1049 37 , D ₇ = 2-5, , 118 ₇ . > - ^V 7 ^; 56 .- .. · / R ₈ = -379, 74 ^D 3 = 86 370 ⁿ 8 - T , 43496 ", ^V 8 = 94, ^R Q = - 725, , 10th ^D 9 = ^D 10 =  10 , 035 66 9 ^R 1O ⁼ - 315, , 23 ^D 11 ^=: 41 , , 000 ; ⁿ 10 = T , 46012 , ^V 10 : r .rr = O ₁ ', 56 ι \ / R ₁₁ = - 675, .25 ^: ti D ₁₂ =  25: 470 1 , 43496 = 94, ι 1 2 ⁼ 188 D ₁₃ - = 10 927 ⁿ 12 = - .. ^V 12 , 66 R ₁₃ = -636, ^D 14 = 39 '. , 000 A ₁₃ = 1 , 46012; . ': - ⁷ 13 = ..67 _! 1 J R ₁₄ = -257, , 23 - ^D T5 = 166th , 433 ' R ₁₅ = 387, , 08 • V ^D 16> 246 , 300: V. r-:; 1 p ) 5 °. , ^R T6 = 19137, , 15. ^D 17 ⁼ .0 600 t , 43496 - «- Vw ^ 'Ζ'. .. '/ ", OO R ₁₇ - = - 202, , 44 ^D 13 = : 19 , 220. 1 , 46012 = 67  p "• -ic, - -1928, 40 I ¹ ^ - ^D 19 = 4 656 ⁿ i3 ^{= T} 13 ^ , 5 0 I - > R-IQ = GD. , 05 ^D 20. ⁼ 1 , 129 • n ₁₉ = 1 , 43496 ; ^V T9 = 94 ,DO R ₂₀ = CD , 73 21 ⁼ 19 , 345 1 , 46012 = 67 R ₂₁ = ^R 22 ⁼ -.661, , 84 ^D 22 = 13 , 030 , -n ₂₁ = ^{: V} 21 , 0O R ₂₃ = 111 , 44 ' ^D 23 ⁼ 3 309 n ₂₂ = , 46012 ..: ^V 22 = 0.7 ^R 2A ⁼ - 434-. , 65 .. ^D 24 = 11 , 515th ^: , 56 - ^R 9 ₅ = 793 10 ^D 25 ⁼ 22 , 875 n ₂₄ - = ' 1 '43496' ^V 24 - 34. fr - • OO ^R 26 ⁼ 163 16 ^D 26 = 16 , 620 1 , 46012 To WR ₂₇ = 2181 D ₂₇ = 7 ^α 2ο ⁼ ' ^V 26 Ro ο ⁼ 1077 ⁿ 27 ⁼ ' ^: - ^V 27 -1,145 33 93 -10,937 - 421

Claims (4)

invention claim 1. Katadioptris.che microrepiece lens with a magnification of -0.5 lb ir -0.1 operating at a centroid wavelength of 265 nm, having a maximum numerical aperture n'sin u '= 0.35 and structures up to 0.6 ^ m, characterized in that it consists of two dioptric assemblies and two identical mirrors arranged on four sides of a partially transparent cube, that is, its four optical axes. lie in a plane and the four outer surfaces of .Ways la. pierced in the centroid, wherein the partially transmissive layer represents a plane that extends from one edge of the cube to the diagonally opposite so that above and below this plane are a dioptric assembly and a mirror, .dioptric assembly and mirror face each other, and object and image plane respectively on the side of a dioptric assembly opposite the division cube. , '. , 2. _{Katadioptrisch.es microrescription lens} according to item 1, characterized in that - all the dioptric components and the partially transparent cube of optical media with a transmission X _OEO V 0.3 for .100 mm Glasweg be ? 50 stand. 3. Katadioptrisch.es Micro reproduction lens according to pt. 1 and 2, characterized in that the Petsvalsummen the two dioptric systems compensate for the mirror as far as possible. 4. Katadioptrisch.es micro reproduction lens according to Pkt. 1 to 3, characterized in that the values are used according to Table 1 for the optical design. For this purpose please refer to the following table