CN1664703B - Polarization pupil device and application thereof in projection lithography system - Google Patents

Abstract

A polarization pupil device comprises a quartz substrate and a polarization film layer on the quartz substrate, wherein the polarization film is divided into a plurality of sector areas, the polarization film layer on each sector area forms a linear polarizer, and the polarization direction of the linear polarizer is in the tangential direction of the radial direction of a pupil; the polarization pupil device is applied to a high-numerical-aperture projection lithography system and comprises an ellipsoidal mirror, a light source, a high-energy high-uniformity illuminating part, a mask plate, a projection lithography objective lens and a silicon wafer, wherein the polarization pupil device for controlling the polarization of imaging light beams is placed on the pupil plane of the projection lithography objective lens, the pupil function of the projection lithography system and the transfer function of the whole projection lithography optical system are changed, the high-numerical-aperture lithography imaging is modulated into TE polarization imaging, the lithography imaging contrast is improved, and the lithography resolution of the short-wavelength high-numerical-aperture projection lithography system is further developed.

Description

A kind of polarizing pupil device and the application in projection lithography system thereof

Affiliated technical field

The present invention is a kind of polarizing pupil device that is used for the high-NA projection lithography system and in the application of projection lithography system, belongs to the VLSI (very large scale integrated circuit) production equipment and repeats projection lithography system and advanced scanning projecting photoetching systems technology field step by step.

Background technology

To the active demand of VLSI (very large scale integrated circuit) device, promoted the develop rapidly of projection optics photoetching technique, for the limit and the life-span that prolongs the projection optics photoetching technique, people have proposed various raising photolithography resolutions and have improved the method for depth of focus.According to Rayleigh equation, the formulate of resolving power and depth of focus is as follows:

Resolving power=k ₁(λ/NA)

Depth of focus=k ₂(λ/NA ²)

Wherein λ is the exposure wavelength of projection lithography system, k ₁And k ₂Be the photoetching process factor.

Therefore can shorten exposure wavelength (λ) and improve resolving power by improving the numerical aperture (NA) of light projection photoetching objective lens, but along with the increase of numerical aperture, the shortening of exposure wavelength, depth of focus reduces rapidly.And along with the increase of numerical aperture, the shortening of exposure wavelength, light distribution is spread along the polarization direction, and is increasing to the influence of litho pattern based on the vector diffraction effect of polarizability.Therefore carry out having become very necessary based on the vector imaging control of polarizability.In the high-NA projection lithography system, can improve the resolving power of optical patterning system by the polarization state of control imaging beam.

Summary of the invention

The technical issues that need to address of the present invention are: overcome above-mentioned the deficiencies in the prior art, and provide a kind of polarizing pupil device that is used for the high-NA projection lithography system, in the high-NA projection lithography system, use the present invention, the pupil function of projection lithography system will be changed, and the transport function of whole projection lithography optical system, the optical patterning of high-NA is modulated into the TE polarization imaging, improve the optical patterning contrast, thereby further improved the photolithography resolution of short wavelength's high-NA projection lithography system.

Technical solution of the present invention is: polarizing pupil device, its characteristics are: be divided into the plurality of sector zone at quartz base plate, be manufactured with polarizing film on each sector region, the polarization direction of polarizing film is in pupil tangential direction radially, all sector regions that are manufactured with polarizing film are formed a circle, and are manufactured with the summit and the round heart coincidence of being formed of the sector region of polarizing film.

Adopt the projection lithography system of above-mentioned polarizing pupil device, comprise ellipsoidal mirror, light source, high-energy high evenly illuminace component, mask plate, light projection photoetching objective lens and silicon chip, its characteristics are: place the polarizing pupil device that imaging beam is carried out Polarization Control on the pupil plane of described light projection photoetching objective lens, the light that light source is launched is collected by ellipsoidal mirror, and light assembled by the high evenly illuminace component lighted mask of high-energy, and the ultra tiny feature pattern on the mask plate by the polarizing pupil device projection imaging in the light projection photoetching objective lens on silicon chip.

The present invention compared with prior art has the following advantages:

(1) polarizing pupil device that is used for the high-NA projection lithography system of the present invention can change the pupil function of projection lithography system, and projection lithography optical system transport function, imaging system has been carried out Polarization Modulation, improve the system transmissions characteristic, reached the purpose that improves the projection imaging photolithography resolution.

(2) in the high-NA projection lithography system, add polarizing pupil device of the present invention, can overcome the deficiency of the low exposure of off-axis illumination and phase shifting mask tolerance limit, high proximity effect, can improve process window significantly, improve productive capacity.

(3) in the high-NA projection lithography system, add polarizing pupil device of the present invention, do not influence the technical parameter of former projection lithography system, therefore can when manufacturing and designing the projecting etching imaging object lens, just consider to add, make the simplicity of design of optical patterning system convenient.

Description of drawings

Fig. 1 is a structure cross-sectional schematic of the present invention;

Fig. 2 looks synoptic diagram for structure master of the present invention;

Fig. 3 is the TE polarization imaging synoptic diagram among the present invention;

Fig. 4 is the TM polarization imaging synoptic diagram among the present invention;

Fig. 5 is applied to the structural representation of high-NA projection lithography system for the present invention.

Embodiment

As shown in Figure 1, 2, the present invention has been divided into plurality of sector zone 3 at quartz base plate 2, be manufactured with polarizing film 1 on each sector region 3, the polarization direction of polarizing film 1 is in pupil tangential direction radially, arrow is represented the polarization direction of linear polarizer among Fig. 1, all sector regions that are manufactured with polarizing film 13 are formed a circle, and are manufactured with the summit and the round heart coincidence of being formed of the sector region 3 of polarizing film 1.Cutting apart as required of sector region 3 chosen, and be generally the smaller the better.

The polarizing film of making on sector region 31 includes the interlaced fluoride materials of multilayer, and the wavelength of the imaging beam of polarizability pupil device transmission is 157nm.

The polarizing film 1 that the interlaced fluoride materials of multilayer is formed is made up of first kind and second kind of two kinds of thin layer, and the thickness of thin layer is quarter-wave, and first kind of thin layer is made up of the lanthanum fluoride material with the refraction coefficient under the 157nm wavelength; Second kind of thin layer also is made up of the aluminium of fluoridizing with the certain refraction coefficient of refraction coefficient under the 157nm wavelength, and first kind of refraction coefficient that thin layer had is greater than second kind of refraction coefficient that thin layer had.

The thickness of first kind of thin layer of the polarizing film of being made up of the interlaced fluoride materials of multilayer 1 and each layer of second kind of thin layer is quarter-wave.

The manufacturing process of polarizing pupil device of the present invention is as follows; at first quartz base plate is divided into the plurality of sector zone; selected sector region; the selected polarizing film of deposition one deck on quartz base plate; the polarization direction of polarizing film is in pupil tangential direction radially, and the polarizing film except selected sector region is etched away, with the sector region protection of the polarizing film of made; then selected next sector region is made, and finishes the making of whole polarizing pupil device like this.

Principle of the present invention: shown in Fig. 3,4, representative be two kinds of polarization imagings: the TE polarization imaging, as shown in Figure 3 and the TM polarization imaging, as shown in Figure 4.The imaging on the silicon chip mainly by 0 grade and ± interference between 1 grade of three beams diffraction light and forming, the interference effect of three beams diffraction light is how, directly has influence on the contrast of imaging.Suppose A _{+ 1}The direction of propagation of order diffraction light be (α, 0, γ), then the three beams diffraction light under TE polarization imaging and the TM polarization imaging is expressed as follows:

The TE polarization imaging:

$A_0=\frac{1}{2}\exp \left(\mathrm{ikz}\right)---\left(1\right)$

$A_{+1}=\frac{1}{\mathrm{\π}}\exp \left[\mathrm{ik}(\mathrm{\αx}+\mathrm{\γz})\right]---\left(2\right)$

$A_{-1}=\frac{1}{\mathrm{\π}}\exp \left[\mathrm{ik}(\mathrm{\γz}-\mathrm{\αx})\right]---\left(3\right)$

The TM polarization imaging:

$A_0=\frac{1}{2}\exp \left(\mathrm{ikz}\right)---\left(4\right)$

$A_{+1}=\frac{1}{\mathrm{\π}}(\mathrm{\γ}-\mathrm{\α})\exp \left[\mathrm{ik}(\mathrm{\αx}+\mathrm{\γz})\right]---\left(5\right)$

$A_{-1}=\frac{1}{\mathrm{\π}}(\mathrm{\α}+\mathrm{\γ})\exp \left[\mathrm{ik}(\mathrm{\γz}-\mathrm{\αx})\right]---\left(6\right)$

Above k in the formula of (1)～(6) be the light wave number, its value is 2 π/λ.

The imaging electric field is by the vector of the electric field of 0 grade and ± 1 grade of three beams diffraction light and forms on the silicon chip, and then the image field on the silicon chip is expressed as:

$A_{\mathrm{TE}}=\frac{1}{2}\exp \left(\mathrm{ikz}\right)+\frac{1}{\mathrm{\π}}\exp \left(\mathrm{ik\γz}\right)[\exp \left(\mathrm{ik\αx}\right)+\exp (-\mathrm{ik\αx})]---\left(7\right)$

$A_{\mathrm{TM}}=\frac{1}{2}\exp \left(\mathrm{ikz}\right)+\frac{\mathrm{\γ}}{\mathrm{\π}}\exp \left(\mathrm{ik\γz}\right)[\exp \left(\mathrm{ik\αx}\right)+\exp (-\mathrm{ik\αx})]$

$-\frac{\mathrm{\α}}{\mathrm{\π}}\exp \left(\mathrm{ik\γz}\right)[\exp \left(\mathrm{ik\αx}\right)-\exp (-\mathrm{ik\αx})]---\left(8\right)$

Just can obtain the intensity distributions of aerial image on the silicon chip by formula (7) and (8), its expression formula is as follows:

$I_{\mathrm{TE}}\left(x\right)=\frac{1}{4}+\frac{2}{\mathrm{\π}}\cos \left(\mathrm{k\αx}\right)\cos \left(\right[k(1-\mathrm{\γ})z]+\frac{4}{{\mathrm{\π}}^2}{\cos }^2\left(\mathrm{k\αx}\right)---\left(9\right)$

$I_{\mathrm{TM}}\left(x\right)=\frac{1}{4}+\frac{2\mathrm{\γ}}{\mathrm{\π}}\cos \left(\mathrm{k\αx}\right)\cos \left[k(1-\mathrm{\γ})z\right]$

$\frac{4}{{\mathrm{\π}}^2}[{\mathrm{\α}}^2+({\mathrm{\γ}}^2-{\mathrm{\α}}^2){\cos }^2\left(\mathrm{k\αx}\right)]---\left(10\right)$

Then TE polarization imaging and TM polarization imaging light intensity log slope value can through type (9) and (10) calculate.

${\mathrm{LS}}_{\mathrm{TE}}=\frac{4\mathrm{\λ}}{\mathrm{\α}}---\left(11\right)$

${\mathrm{LS}}_{\mathrm{TM}}=\frac{4\mathrm{\λ}}{\mathrm{\α}}\frac{{(1-{\mathrm{\α}}^2)}^2}{1+16{\mathrm{\α}}^2/{\mathrm{\π}}^2}---\left(12\right)$

Can obtain from formula (11) and (12): the TE polarization imaging has higher light intensity log slope value than TM polarization imaging, and this is because in formula (12), except having 4 λ/α, also has one less than 1 coefficient.In traditional unpolarized imaging, light intensity log slope value is light intensity log slope value average of TE polarization imaging and TM polarization imaging both of these case, so the S polarization imaging has higher light intensity log slope value than unpolarized imaging.When the TE polarization imaging, the electric vector vibration direction of the three beams diffraction light of imaging on silicon chip all is identical, and shown in Fig. 3,4, all perpendicular to the plane of incidence, so the interference effect between the three beams diffraction light reaches best, and corresponding light intensity log slope value is also the highest; And when the TM polarization imaging, the direction of vibration of the electric vector of the three beams diffraction light of imaging on silicon chip changes along with the angle of each diffracted beam direction of propagation, shown in Fig. 3,4, interference effect between the three beams diffraction light is during just not as the TE polarization imaging, and corresponding light intensity log slope value is also not as the TE polarization imaging.In a word, in TE polarization imaging, TM polarization imaging and unpolarized imaging, the TE polarization imaging has the highest light intensity log slope value.

As shown in Figure 5, for the present invention is applied to the high-NA projection lithography system, it is made of ellipsoidal mirror 4, light source 5, high-energy high evenly illuminace component 6, mask plate 7, light projection photoetching objective lens 8, polarizing pupil device 9 and silicon chip 10 etc., the light that light source 5 is launched is collected by ellipsoidal mirror 4, and light assembled by high evenly illuminace component 6 lighted masks 7 of high-energy, and the ultra tiny feature pattern on the mask plate 7 by light projection photoetching objective lens 8 projection imagings on silicon chip 10.Pupil plane at the high-NA light projection photoetching objective lens is placed the polarizing pupil device 9 that imaging beam is carried out Polarization Control, polarizing pupil device has changed the pupil function of projection lithography system, and the transport function of projection lithography system optical system, optical patterning is modulated into the S polarization imaging, the electric field direction of vibration of diffracted beam that is different progression is identical, interference effect is best, improve the optical patterning contrast, further excavated the photoetching definition of short wavelength's large-numerical aperture projection optics optical patterning system.

Claims (2)

1. polarizing pupil device, it is characterized in that: be divided into the plurality of sector zone at quartz base plate, be manufactured with polarizing film on each sector region, the polarization direction of the polarizing film of made is in pupil tangential direction radially, all are manufactured with the sector region of polarizing film and form a circle, and are manufactured with the summit and the round heart coincidence of being formed of the sector region of polarizing film; Described polarizing film constitutes by including the interlaced fluoride materials of multilayer, the interlaced fluoride materials of described multilayer is made up of first kind and second kind of two kinds of thin layer, first kind of thin layer is made up of the fluoride with the refraction coefficient under the 157nm wavelength, second kind of thin layer also is made up of the fluoride with the refraction coefficient under the 157nm wavelength, and first kind of refraction coefficient that thin layer had is greater than second kind of refraction coefficient that thin layer had; Described first kind of thin layer includes one deck lanthanum fluoride material at least, and described second kind of thin layer includes one deck aluminum fluoride material at least; Described polarizing film method for making is: at first quartz base plate is divided into the plurality of sector zone; selected sector region; the selected polarizing film of deposition one deck on quartz base plate; the polarization direction of polarizing film is in pupil tangential direction radially; polarizing film except selected sector region is etched away; with the sector region protection of the polarizing film of made, then selected next sector region is made, and finishes the making of whole polarizing pupil device like this.

2. adopt the projection lithography system of above-mentioned polarizing pupil device, comprise ellipsoidal mirror, light source, high-energy high evenly illuminace component, mask plate, light projection photoetching objective lens and silicon chip, it is characterized in that: on the pupil plane of described light projection photoetching objective lens, place the polarizing pupil device that imaging beam is carried out Polarization Control, the light that light source is launched is collected by ellipsoidal mirror, and light assembled by the high evenly illuminace component lighted mask of high-energy, the ultra tiny feature pattern on the mask plate by the polarizing pupil device projection imaging in the light projection photoetching objective lens on silicon chip.

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