CN103726019B - Improve the method for design of the baffle plate of spherical optics element plated film homogeneity - Google Patents

Abstract

A kind of plate design method for improving spherical optics element plated film homogeneity in planetary rotation system coating equipment.Set up plated film model and devise the plane modifying mask with parabolic outlines.Baffle plate of the present invention be used for plated film experiment show, in clear aperture and radius-of-curvature ratio range (-1.9 ~+1.9), improve film uniformity reach more than 97.5%, and to convex spherical optical element and concave spherical surface optical element all applicable.

Description

Improve the method for design of the baffle plate of spherical optics element plated film homogeneity

Technical field

The present invention relates to field of film preparation, particularly in a kind of planetary rotation system coating equipment, improve the plate design method of spherical optics element plated film homogeneity.

Background technology

Optical thin film is the indispensable composition device of contemporary optics system, which imparts the various performance of optical element, plays an important role to the quality of opticinstrument.Optical thin film element is widely used in optical field, has the ground of light conveniently to have the shadow of optical thin film.Along with the development of contemporary optics system, higher requirement be it is also proposed to the performance of optical thin film.Nowadays, a lot of optical imaging system is just towards the future development of large-numerical aperture.Among these systems, there is various optical element, is much wherein the spherical optics element with large clear aperature and radius-of-curvature ratio.Usually, these spherical optics elements to be coated with the homogeneous optical thin film of thickness, and then control transmissivity or reflectivity homogeneity and wavefront error, otherwise can image quality be had a strong impact on.

Nowadays there is multiple method to improve optical element film coated homogeneity, comprise and use single axle rotation system and planetary rotation system, use modifying mask or amendment planetary rotation operation scheme.Usually, planetary rotation system than the good uniformity of single axle rotation system, but can not be applicable to spherical optics element when not using baffle plate, because the thickness of spherical optics element sharply changes in the radial direction.Use modifying mask selectively to block sedimentation rate ratio position faster on optical element, significantly can improve the homogeneity of plated film.Wherein, fixed correction plate washer machine is installed simple and easy, and repeatability is high, is widely used.But, at present for the design of planetary rotation system correction plate washer, mainly rely on the initial baffle plate of empirical design, then repeatedly revise baffle shapes by great many of experiments, finally reach the uniformity requirement of expection.This process not only wastes time and energy, and also requires that slip-stick artist has rich experience.Particularly for different spherical optics elements, need different modifying masks, once in the face of there being the engineering of multiple spherical optics element, use this empirical method obviously can not effectively finish the work.

Summary of the invention

The object of the present invention is to provide the plate design method improving spherical optics element plated film homogeneity in a kind of planetary rotation system coating equipment, based on computer simulation, determine the shape of baffle plate and the method for position of the optical element film coated homogeneity of planetary rotation system coating equipment Internal Spherical Surface fast and accurately.

Technical solution of the present invention is as follows:

Improve a plate design method for spherical optics element plated film homogeneity in planetary rotation system coating equipment, it is characterized in that the method comprises the following steps:

(1) according to the vacuum chamber configuring condition of planetary rotation system coating equipment, the optical element film coated model of planetary rotation system coating equipment Internal Spherical Surface is set up:

On planetary rotation fixture, a clear aperture is CA, radius-of-curvature is the aspherical elements Sub of RoC, a point P (x on this aspherical elements, y, z), the thickness be evaporated in the unit time on this aspect is (F.Villa and O.Pompa, " Emission pattern of real vapor sources in high vacuum:anoverview; " Appl.Opt.38,695-703 (1999)):

Wherein, A is a constant; R is from evaporation source S (x _s, y _s, z _s) point to a length of the vector r of P (x, y, z); be the angle of evaporation source surface normal vector s and described vector r, namely evaporate angle; θ is that a p points to centre of sphere O (x _o, y _o, z _o) vector C and the angle of vector r, i.e. deposition angles; N is evaporation source evaporation characteristic parameter, and planetary rotation dish is parallel with evaporation source S and spherical optics element Sub is placed in planetary plate center, and thickness expression formula is transformed in rectangular coordinate system and can be obtained:

$r=\left|r\right|=\sqrt{{\left({x-x}_s\right)}^2+{\left({y-y}_s\right)}^2+{\left({z-z}_s\right)}^2}---\left(2\right)$

$\cos \mathrm{\θ}={(-1)}^M\frac{r\·c}{\left|r\right|\·\left|c\right|}=\frac{\left({x-x}_s\right)(x_o-x)+\left({y-y}_s\right)(y_o-y)+\left({z-z}_s\right)(z_o-z)}{r\·\mathrm{RoC}}---\left(4\right)$

$\left\{\begin{array}{c}{x}_o=R\sin \mathrm{\α}\\ y_o=R\cos \mathrm{\α}\\ z_o=H+{(-1)}^M\sqrt{{\mathrm{RoC}}^2-{\mathrm{CA}}^2/4}\end{array}\right.---\left(5\right)$

$\left\{\begin{array}{c}x=R\sin \mathrm{\α}+L\sin (\mathrm{K\α}+\mathrm{\α}+\mathrm{\β})\\ y=R\cos \mathrm{\α}+L\cos (\mathrm{K\α}+\mathrm{\α}+\mathrm{\β})\\ z=H+{(-1)}^M(\sqrt{{\mathrm{RoC}}^2-{\mathrm{CA}}^2/4}-\sqrt{{\mathrm{RoC}}^2-L^2})\end{array}\right.---\left(6\right)$

Wherein M is used for distinguishing concavo-convex sphere, for convex spherical M=0, is planetary orbit radius for concave spherical surface M=1, R, L is the horizontal throw of a P to centre of sphere O and L ∈ [0, CA/2], K are planetary plate rotation and revolution rotating ratio, H is planetary plate height, and α is planetary plate revolution angle, and β is the point initial rotation angle of P and β ∈ [0,2 π], through above-mentioned conversion, for the aspherical elements parameter (CA determined, RoC, M), coating equipment configuration parameter (R, K, H, x _s, y _s, z _s) and evaporation source evaporation characteristic parameter n, the thickness in formula (1) can be converted into the function t (L of independent variable(s) (L, β, α), β, α), when after revolution certain angle, the thickness of some P is t (L, β, α) integration to α, be

$t(L,\mathrm{\β})=\underset{0}{\overset{2\mathrm{\πF}}{\∫}}t(L,\mathrm{\β},\mathrm{\α})\mathrm{d\α}---\left(7\right)$

Wherein F is the revolution number of turns, and (L, β) determines the position of a P on aspherical elements, and t (L, β) determines the film thickness distribution on whole aspherical elements;

(2) add from shade corrected parameter E (L, β, α):

Convex spherical element from shade corrected parameter be:

For concave spherical surface element, the z on the straight line of tie point P and evaporation source S _b1 B (x of=H _b, y _b, z _b) coordinate be:

$\left\{\begin{array}{c}{x}_b=\left({x-x}_s\right)(H-z_s)/\left({z-z}_s\right)+x_s\\ y_b=\left({y-y}_s\right)\left({H-z}_s\right)/\left({z-z}_s\right)+y_s\\ z_b=H_b\end{array}\right.---\left(9\right)$

This point is to clear aperture center (x _o, y _o, H) distance be then

$E(L,\mathrm{\β},\mathrm{\α})=\left\{\begin{array}{cc}1,& d\≤\mathrm{CA}/2\\ 0,& d>\mathrm{CA}/2\end{array}\right.---\left(10\right)$

Now thickness is film thickness when not adding modifying mask, spherical optics element being put P, and the thickness of formula (7) becomes:

$t(L,\mathrm{\β})=\underset{0}{\overset{2\mathrm{\πF}}{\∫}}t(L,\mathrm{\β},\mathrm{\α})E(L,\mathrm{\β},\mathrm{\α})\mathrm{d\α}---\left(11\right)$

Calculate the some thickness of different positions, obtain spherical optics element without film thickness distribution during baffle plate;

(3) distribute by the theoretical distribution compared without thickness on spherical optics element during modifying mask determine the evaporation characteristic n of evaporation source with experiment:

Perforate in the radial direction on the fixture with the radius-of-curvature identical with spherical optics element and clear aperture, bare substrate is placed in different radial positions, this fixture is arranged on planetary plate center and does substrate, in without modifying mask situation, optical thin film is coated with according to the actual processing condition being coated with optical thin film, film thickness measuring is carried out to the substrate of each plated film, the thickness of optical element corresponding position is represented with on-chip thickness, after drawing out actual thickness distribution curve, with the evaporation characteristic n value of evaporation source for the theoretical film thickness distribution curve calculated by formula (11) and actual thickness distribution curve use method of least squares to carry out matching by variable, n value when objective function is minimum value is the evaporation characteristic n value in actual evaporation source,

(4) shape and the position of the modifying mask of the optical element film coated homogeneity of planetary rotation system coating equipment Internal Spherical Surface is determined:

One is had the plane modifying mask Mask of parabolic outlines, be fixed in vacuum chamber, the system of equations undetermined of baffle plate profile is:

$\left\{\begin{array}{cc}{y}_{\mathrm{mask}}=a_1{(x_{\mathrm{mask}}+a_2)}^2+a_3& x_{\mathrm{mask}}\∈\left[a_{4,}{a}_5\right]\\ y_{\mathrm{mask}}=a_6{(x_{\mathrm{mask}}+a_7)}^2+a_8& x_{\mathrm{mask}}\∈\left[a_{4,}{a}_5\right]\\ x_{\mathrm{mask}}=a_4& \\ x_{\mathrm{mask}}=a_5& \end{array}\right.---\left(12\right)$

Wherein, (x _mask, y _mask) be the coordinate that baffle plate skeletal lines is put, (a ₁, a ₂, a ₃, a ₄, a ₅, a ₆, a ₇, a ₈) be the undetermined parameter of equation undetermined, y _mask=a ₁(x _mask+ a ₂) ²+ a ₃x _mask∈ [a ₄, a ₅] and y _mask=a ₆(x _mask+ a ₇) ²+ a ₈x _mask∈ [a _4,a ₅] represent two para-curves, x _mask=a ₄and x _mask=a ₅represent two straight lines, these four lines surround an enclosed region Ar and baffle area, and height of baffle plate is H _m, the straight line of tie point P and evaporation source S is being highly z _m=H _m1 D (x at place _m, y _m, z _m) coordinate be:

$\left\{\begin{array}{c}{x}_m=\left({x-x}_s\right)(z_m-z_s)/\left({z-z}_s\right)+x_s\\ y_m=\left({y-y}_s\right)(z_m-z_s)/\left({z-z}_s\right)+y_s\\ z_m=H_m\end{array}\right.---\left(13\right)$

As a D (x _m, y _m, z _m) in above-mentioned baffle area Ar time, i.e. during the straight-line pass baffle area Ar of tie point P and evaporation source S, vapor molecule is corrected plate washer and blocks, N (L, β, α)=0; As a D (x _m, y _m, z _m) when above-mentioned baffle area Ar is outer, vapor molecule is not corrected plate washer and blocks, N (L, β, α)=1; The thickness of above-mentioned plane modifying mask is adopted to be:

$t(L,\mathrm{\β})=\underset{0}{\overset{2\mathrm{\πF}}{\∫}}t(L,\mathrm{\β},\mathrm{\α})E(L,\mathrm{\β},\mathrm{\α})N(L,\mathrm{\β},\mathrm{\α})\mathrm{d\α}---\left(14\right)$

At L ∈ [0, CA/2], calculate the thickness at different positions place on aspherical elements in β ∈ [0,2 π] scope, obtain the thickness t of thickest point _max, on aspherical elements, the relative thickness at different positions place is

The relative thickness Relt at thickness the thinnest some place on aspherical elements _minbe the plated film homogeneity of aspherical elements, use Merit is target equation

Merit＝100%-Relt _min（16）

Use the Optimization Toolbox of Matlab software, for baffle plate equation parameter (a simultaneously ₁, a ₂, a ₃, a ₄, a ₅, a ₆, a ₇, a ₈) and height of baffle plate H _minput initial parameter, the uniformity requirement Merit determined with is target equation use computer optimization baffle plate equation parameter (a ₁, a ₂, a ₃, a ₄, a ₅, a ₆, a ₇, a ₈) and height of baffle plate H _m, obtain shape and the position of baffle plate;

(5) when the homogeneity when use baffle plate is optimized does not reach necessary requirement, add a baffle plate, different parametric equations is adopted from first baffle plate, more equation parameter is provided to be optimized, one is added again as do not reached uniformity requirement, by that analogy, till aspherical elements plated film homogeneity reaches requirement.

Described testing plate measured film thickness method adopts light-intensity method or Ellipsometric.

The method of calculation of described use computer optimization baffle plate equation parameter have simulated annealing, genetic algorithm.

The present invention is major advantage compared with prior art:

The present invention designs baffle plate by computer simulation is disposable, baffle plate of the present invention is used for plated film experiment and shows, in clear aperture and radius-of-curvature ratio range (-1.9 ~+1.9), improve film uniformity reach more than 97.5%, and to convex spherical optical element and concave spherical surface optical element all applicable.

Accompanying drawing explanation

Fig. 1 is the optical element film coated process schematic of planetary rotation system coating equipment Internal Spherical Surface.

Fig. 2 is the convex spherical optical element fixture schematic diagram of RoC=128mm, a CA=196mm.

Fig. 3 is hot boat evaporation AlF when not using baffle plate ₃film is in the suprabasil theoretical film thickness distribution of the convex spherical of RoC=128mm, CA=196mm and actual experiment result.

Fig. 4 is the convex spherical optical element film uniformity modifying mask schematic diagram of modified R oC=128mm, CA=196mm.

Fig. 5 is not for using the theoretical film thickness distribution figure of the convex spherical optical element of RoC=128mm, CA=196mm before modifying mask.

The theoretical film thickness distribution figure of convex spherical optical element that Fig. 6 is RoC=128mm, CA=196mm after use modifying mask.

Fig. 7 is after using modifying mask, the AlF at the convex spherical optical element different positions place of RoC=128mm, CA=196mm ₃unitary film reflection spectrum test result.

Embodiment

Be that example is described to improve the optical element film coated homogeneity of convex spherical of a radius of curvature R oC=128mm, clear aperture CA=196mm in planetary rotation system coating equipment Leybold Optics SYRUSpro1110, require that homogeneity correction reaches more than 98%.

(1) Fig. 1 is the optical element film coated process schematic of planetary rotation system coating equipment Internal Spherical Surface, and planetary plate is parallel to evaporation source S (x _s, y _s, z _s), it is CA that clear aperture is one by one placed at planetary plate center, and the radius-of-curvature point that to be the aspherical elements Sub of RoC, P (x, y, z) be on lens, r is from evaporation source S (x _s, y _s, z _s) point to the length of vector r of some P, be the angle of evaporation source surface normal vector s and vector r, θ is that optical element surface bin p points to centre of sphere O (x _o, y _o, z _o) vector C and the angle of vector r, R is planetary orbit radius, and L is the horizontal throw of a P to centre of sphere O, and H is planetary plate height, and α is planetary plate revolution angle, and β is the initial rotation angle of some P, and n is evaporation source evaporation characteristic parameter.The thickness be evaporated in unit time on a P is

Wherein A is a constant.Planetary rotation dish is parallel with evaporation source S and spherical optics element Sub is placed in planetary plate center, and thickness expression formula is transformed in rectangular coordinate system and can be obtained:

$r=\left|r\right|=\sqrt{{\left({x-x}_s\right)}^2+{\left({y-y}_s\right)}^2+{\left({z-z}_s\right)}^2}---\left(2\right)$

$\cos \mathrm{\θ}={(-1)}^M\frac{r\·c}{\left|r\right|\·\left|c\right|}=\frac{\left({x-x}_s\right)(x_o-x)+\left({y-y}_s\right)(y_o-y)+\left({z-z}_s\right)(z_o-z)}{r\·\mathrm{RoC}}---\left(4\right)$

$\left\{\begin{array}{c}{x}_o=R\sin \mathrm{\α}\\ y_o=R\cos \mathrm{\α}\\ z_o=H+{(-1)}^M\sqrt{{\mathrm{RoC}}^2-{\mathrm{CA}}^2/4}\end{array}\right.---\left(5\right)$

$\left\{\begin{array}{c}x=R\sin \mathrm{\α}+L\sin (\mathrm{K\α}+\mathrm{\α}+\mathrm{\β})\\ y=R\cos \mathrm{\α}+L\cos (\mathrm{K\α}+\mathrm{\α}+\mathrm{\β})\\ z=H+{(-1)}^M(\sqrt{{\mathrm{RoC}}^2-{\mathrm{CA}}^2/4}-\sqrt{{\mathrm{RoC}}^2-L^2})\end{array}\right.---\left(6\right)$

Wherein M is used for distinguishing concavo-convex sphere, for convex spherical M=0, be planetary orbit radius for concave spherical surface M=1, R, L is the horizontal throw of a P to centre of sphere O and L ∈ [0, CA/2], K is planetary plate rotation and revolution rotating ratio, and H is planetary plate height, and α is planetary plate revolution angle, β is the point initial rotation angle of P and β ∈ [0,2 π].

Through above-mentioned conversion, for the aspherical elements parameter (CA, RoC, M) determined, coating equipment configuration parameter (R, K, H, x _s, y _s, z _s) and evaporation source evaporation characteristic parameter n, the thickness in formula (1) can be converted into the function t (L of independent variable(s) (L, β, α), β, α), when after revolution certain angle, the thickness of some P is t (L, β, α) integration to α, be

$t(L,\mathrm{\β})=\underset{0}{\overset{2\mathrm{\πF}}{\∫}}t(L,\mathrm{\β},\mathrm{\α})\mathrm{d\α}---\left(7\right)$

Wherein F is the revolution number of turns, and (L, β) determines the position of a P on aspherical elements, and t (L, β) determines the film thickness distribution on whole aspherical elements.

A radius of curvature R oC=128mm in planetary rotation system coating equipment Leybold Optics SYRUSpro1110 is improved for this example, the optical element film coated homogeneity of convex spherical of clear aperture CA=196mm, aspherical elements parameter (CA, RoC, M) is (196mm, 128mm, 1), coating equipment configuration parameter (R, K, H, x _s, y _s, z _s) be (300mm, 131/19,730mm ,-230mm, 165mm, 0mm), revolution number of turns F=38.

(2) add from shade corrected parameter E (L, β, α), for this convex spherical element, deposition E (L, β, α)=0 can not be completed when deposition angles θ is greater than 90 °, otherwise E (L, β, α)=1 can be deposited.The lens thickness then do not added when revising plate washer is used instead represent.

(3) distribute by the theoretical distribution compared without thickness on optical element during modifying mask determine the evaporation characteristic n of evaporation source with experiment.Fig. 2 is the convex spherical optical element fixture schematic diagram of a radius of curvature R oC=128mm, clear aperture CA=196mm.In the perforate in the radial direction of fixture, different radial positions is placed bare substrate (diameter 15mm, 11 substrates), this fixture is arranged on planetary plate center and does substrate, be coated with the processing condition that optical thin film is be coated with aluminum fluoride (AlF according to actual in without baffle plate situation ₃) film, film thickness measuring is carried out to the substrate of each plated film, represents the thickness of optical element corresponding position with on-chip thickness, draw out actual thickness distribution plan, with the evaporation characteristic n value of evaporation source for variable will pass through the theoretical film thickness distribution curve calculated and actual thickness distribution curve use method of least squares to carry out matching, and n value when objective function is minimum value is the evaporation characteristic n value in actual evaporation source.Fig. 3 is hot boat evaporation AlF when not using baffle plate ₃film is in the suprabasil theoretical thickness (curve) of this convex spherical and actual film thickness distribution (point), and the evaporation characteristic obtaining evaporation source is 2 ± 0.2.

(4) add modifying mask equation N (L, β, α), determine shape and the position of the modifying mask of the optical element film coated homogeneity of planetary rotation system coating equipment Internal Spherical Surface;

When adopting a plane modifying mask, the system of equations undetermined of baffle plate profile is:

$\left\{\begin{array}{cc}{y}_{\mathrm{mask}}=a_1{(x_{\mathrm{mask}}+a_2)}^2+a_3& x_{\mathrm{mask}}\∈\left[a_{4,}{a}_5\right]\\ y_{\mathrm{mask}}=a_6{(x_{\mathrm{mask}}+a_7)}^2+a_8& x_{\mathrm{mask}}\∈\left[a_{4,}{a}_5\right]\\ x_{\mathrm{mask}}=a_4& \\ x_{\mathrm{mask}}=a_5& \end{array}\right.---\left(8\right)$

Wherein, (x _mask, y _mask) be the coordinate that baffle plate skeletal lines is put, (a ₁, a ₂, a ₃, a ₄, a ₅, a ₆, a ₇, a ₈) be the undetermined parameter of equation undetermined, y _mask=a ₁(x _mask+ a ₂) ²+ a ₃x _mask∈ [a _4,a ₅] and y _mask=a ₆(x _mask+ a ₇) ²+ a ₈x _mask∈ [a _4,a ₅] represent two para-curves, x _mask=a ₄and x _mask=a ₅represent two straight lines, these four lines surround an enclosed region Ar and baffle area.Height of baffle plate is H _m, the straight line of tie point P and evaporation source S is being highly z _m=H _m1 D (x at place _m, y _m, z _m) coordinate be:

$\left\{\begin{array}{c}{x}_m=\left({x-x}_s\right)(z_m-z_s)/\left({z-z}_s\right)+x_s\\ y_m=\left({y-y}_s\right)(z_m-z_s)/\left({z-z}_s\right)+y_s\\ z_m=H_m\end{array}\right.---\left(9\right)$

As a D (x _m, y _m, z _m) in above-mentioned baffle area Ar time, i.e. during the straight-line pass baffle area Ar of tie point P and evaporation source S, vapor molecule is corrected plate washer and blocks, N (L, β, α)=0; As a D (x _m, y _m, z _m) when above-mentioned baffle area Ar is outer, vapor molecule is not corrected plate washer and blocks, N (L, β, α)=1; The thickness of above-mentioned plane modifying mask is adopted to be:

$t(L,\mathrm{\β})=\underset{0}{\overset{2\mathrm{\πF}}{\∫}}t(L,\mathrm{\β},\mathrm{\α})E(L,\mathrm{\β},\mathrm{\α})N(L,\mathrm{\β},\mathrm{\α})\mathrm{d\α}---\left(10\right)$

At L ∈ [0, CA/2], calculate the thickness at different positions place on aspherical elements in β ∈ [0,2 π] scope, obtain the thickness t of thickest point _max, on aspherical elements, the relative thickness at different positions place is

The relative thickness Relt at thickness the thinnest some place on aspherical elements _minbe the plated film homogeneity of aspherical elements, use Merit is target equation

Merit＝100%-Relt _min（12）

Use the Optimization Toolbox of Matlab software, for baffle plate equation parameter (a simultaneously ₁, a ₂, a ₃, a ₄, a ₅, a ₆, a ₇, a ₈) and height of baffle plate H _minput initial parameter, reaching more than 98% with uniformity requirement is that Merit<2% is for target equation use computer optimization baffle plate equation parameter (a ₁, a ₂, a ₃, a ₄, a ₅, a ₆, a ₇, a ₈) and height of baffle plate H _m, calculating shape and the position of baffle plate, showing through optimizing, use the optimum result of a baffle plate can not reach uniformity requirement more than 98%;

(5) because the optimum result of a baffle plate can not reach uniformity requirement more than 98%, add a baffle plate, different parametric equations is adopted from first baffle plate, more equation parameter is provided to be optimized, one is added again as do not reached uniformity requirement, by that analogy, till aspherical elements plated film homogeneity reaches requirement, this example finally adopts 4 modifying mask optimum result to reach uniformity requirement more than 98%.The system of equations undetermined of 4 baffle plates is:

A baffle plate:

$\left\{\begin{array}{cc}{y}_{\mathrm{mask}}=a_1{(x_{\mathrm{mask}}+a_2)}^2+a_3& x_{\mathrm{mask}}\&Element;\left[a_{4,}{a}_5\right]\\ y_{\mathrm{mask}}={-a}_1{(x_{\mathrm{mask}}+a_2)}^2+a_3& x_{\mathrm{mask}}\&Element;\left[a_{4,}{a}_5\right]\\ y_{\mathrm{mask}}=a_4& \\ y_{\mathrm{mask}}=a_5& \end{array}\right.$

No. two baffle plates:

$\left\{\begin{array}{cc}{y}_{\mathrm{mask}}=a_6{(x_{\mathrm{mask}}+a_7)}^2+a_8& x_{\mathrm{mask}}\&Element;\left[a_{9,}{a}_{10}\right]\\ y_{\mathrm{mask}}={-a}_6{(x_{\mathrm{mask}}+a_7)}^2+a_8& x_{\mathrm{mask}}\&Element;\left[a_{9,}{a}_{10}\right]\\ y_{\mathrm{mask}}=a_9& \\ y_{\mathrm{mask}}=a_{10}& \end{array}\right.$

No. three baffle plates:

$\left\{\begin{array}{cc}{x}_{\mathrm{mask}}=a_{11}{(y_{\mathrm{mask}}+a_{12})}^2+a_{13}& y_{\mathrm{mask}}\&Element;\left[a_{14,}{a}_{15}\right]\\ x_{\mathrm{mask}}={-a}_{11}{(y_{\mathrm{mask}}+a_{12})}^2+a_{13}& y_{\mathrm{mask}}\&Element;\left[a_{14,}{a}_{15}\right]\\ x_{\mathrm{mask}}=a_{14}& \\ x_{\mathrm{mask}}=a_{15}& \end{array}\right.$

No. four baffle plates:

$\left\{\begin{array}{cc}{x}_{\mathrm{mask}}=a_{11}{(y_{\mathrm{mask}}-a_{12})}^2+a_{13}& y_{\mathrm{mask}}\&Element;[{-a}_{14,}-a_{15}]\\ x_{\mathrm{mask}}={-a}_{11}{(y_{\mathrm{mask}}-a_{12})}^2+a_{13}& y_{\mathrm{mask}}\&Element;[-a_{14,}-a_{15}]\\ x_{\mathrm{mask}}={-a}_{14}& \\ x_{\mathrm{mask}}={-a}_{15}& \end{array}\right.$

4 height of baffle plate H _mall identical, use Matlab software to baffle plate undetermined parameter

(a ₁, a ₂, a ₃, a ₄, a ₅, a ₆, a ₇, a ₈, a ₉, a ₁₀, a ₁₁, a ₁₂, a ₁₃, a ₁₄, a ₁₅, H _m) input initial parameter

(-1,100,100 ,-100 ,-100 ,-1 ,-100 ,-100 ,-100 ,-100,1 ,-100 ,-100,100,100,650) are optimized, and finally obtain optimized parameter, and the height of four baffle plates is all H _m=670mm, Fig. 4 are uniformity correcting baffle plate schematic diagram, and baffle plate equation is respectively:

A baffle plate:

$\left\{\begin{array}{cc}{y}_{\mathrm{mask}}=-0.011{(x_{\mathrm{mask}}+316.84)}^2+195.22& x_{\mathrm{mask}}\&Element;[-184.44,-449.24]\\ y_{\mathrm{mask}}=0.011{(x_{\mathrm{mask}}+316.84)}^2-195.22& x_{\mathrm{mask}}\&Element;[-184.44,-449.24]\\ y_{\mathrm{mask}}=-184.44& \\ y_{\mathrm{mask}}=-449.24& \end{array}\right.$

No. two baffle plates:

$\left\{\begin{array}{cc}{y}_{\mathrm{mask}}=-0.0046{(x_{\mathrm{mask}}+300.19)}^2+245.11& x_{\mathrm{mask}}\&Element;[168.25,450]\\ y_{\mathrm{mask}}=0.0046{(x_{\mathrm{mask}}+300.19)}^2-245.11& x_{\mathrm{mask}}\&Element;[168.25,450]\\ y_{\mathrm{mask}}=168.25& \\ y_{\mathrm{mask}}=450& \end{array}\right.$

No. three baffle plates:

$\left\{\begin{array}{cc}{x}_{\mathrm{mask}}=0.01{(y_{\mathrm{mask}}-334.29)}^2-273.74& y_{\mathrm{mask}}\&Element;[171.95,450]\\ x_{\mathrm{mask}}=-0.01{(y_{\mathrm{mask}}-334.29)}^2+273.74& y_{\mathrm{mask}}\&Element;[171.95,450]\\ x_{\mathrm{mask}}=171.95& \\ x_{\mathrm{mask}}=450& \end{array}\right.$

No. four baffle plates:

$\left\{\begin{array}{cc}{x}_{\mathrm{mask}}=0.01{(y_{\mathrm{mask}}+334.29)}^2-273.74& y_{\mathrm{mask}}\&Element;[-171.95,-450]\\ x_{\mathrm{mask}}=-0.01{(y_{\mathrm{mask}}+334.29)}^2+273.74& y_{\mathrm{mask}}\&Element;[-171.95,-450]\\ x_{\mathrm{mask}}=-171.95& \\ x_{\mathrm{mask}}=-450& \end{array}\right.$

Fig. 5 does not use the theoretical film thickness distribution figure of the convex spherical optical element of RoC=128mm, CA=196mm before modifying mask, and now film uniformity can find out to be 53% by scale.Fig. 6 is the theoretical film thickness distribution figure of this convex spherical optical element after use modifying mask.After uniformity baffle correction, the homogeneity of theoretical thickness reaches more than 98.5%.Fig. 7 be use this convex spherical optical element different positions place after modifying mask substrate on AlF ₃unitary film reflection spectrum test result, reflectance curve overlaps substantially, and the film uniformity being gone out different positions place by spectra inversion reaches more than 98.9%, indicates the validity of this model.

In a word, the present invention proposes a kind of uniformity correcting baffle plate by computer optimization with parabolic outlines to improve the method for the optical element film coated homogeneity of planetary rotation system coating equipment Internal Spherical Surface.In thermal evaporation, ion beam sputtering, magnetron sputtering, in the physical gas-phase depositions such as molecular-layer deposition, on planetary rotation fixture, plated film even row modifying mask can adopt same way, all belongs to protection scope of the present invention.Compared with existing spherical optics element plated film homogeneity correction plate washer method of design, the present invention more efficiently can design baffle plate fast, in very large clear aperture and radius-of-curvature ratio range, improve film uniformity, and all applicable to convex-concave spherical optics element.

Non-elaborated part of the present invention belongs to techniques well known.

Claims (3)

1. improve a plate design method for spherical optics element plated film homogeneity in planetary rotation system coating equipment, it is characterized in that the method comprises the following steps:

(1) according to the vacuum chamber configuring condition of planetary rotation system coating equipment, the optical element film coated model of planetary rotation system coating equipment Internal Spherical Surface is set up:

On planetary rotation fixture, a clear aperture is CA, and radius-of-curvature is the aspherical elements Sub of RoC, a some P (x, y, z) on this aspherical elements, and the thickness be evaporated in the unit time on this aspect is:

Wherein, A is a constant; R is from evaporation source S (x _s, y _s, z _s) point to a length of the vector r of P (x, y, z); be the angle of evaporation source surface normal vector s and described vector r, namely evaporate angle; θ is that a p points to centre of sphere O (x _o, y _o, z _o) vector C and the angle of vector r, i.e. deposition angles; N is evaporation source evaporation characteristic parameter, and planetary rotation dish is parallel with evaporation source S and spherical optics element Sub is placed in planetary plate center, in rectangular coordinate system:

$r=\left|r\right|=\sqrt{{(x-x_s)}^2+{(y-y_s)}^2+{(z-z_s)}^2}---\left(2\right)$

$\cos \mathrm{\&theta;}={(-1)}^M\frac{r\&CenterDot;c}{\left|r\right|\&CenterDot;\left|c\right|}=\frac{(x-x_s)(x_o-x)+(y-y_s)(y_o-y)+(z-z_s)(z_o-z)}{r\&CenterDot;\mathrm{RoC}}---\left(4\right)$

$\left\{\begin{array}{c}{x}_o=R\sin \mathrm{\&alpha;}\\ y_o=R\cos \mathrm{\&alpha;}\\ z_o=H+{(-1)}^M\sqrt{{\mathrm{RoC}}^2-{\mathrm{CA}}^2/4}\end{array}\right.---\left(5\right)$

$\left\{\begin{array}{c}x=R\sin \mathrm{\&alpha;}+L\sin (\mathrm{K\&alpha;}+\mathrm{\&alpha;}+\mathrm{\&beta;})\\ y=R\cos \mathrm{\&alpha;}+L\cos (\mathrm{K\&alpha;}+\mathrm{\&alpha;}+\mathrm{\&beta;})\\ z=H+{(-1)}^M(\sqrt{{\mathrm{RoC}}^2-{\mathrm{CA}}^2/4}-\sqrt{{\mathrm{RoC}}^2-L^2})\end{array}\right.---\left(6\right)$

Wherein M is used for distinguishing concavo-convex sphere, for convex spherical M=0, is planetary orbit radius for concave spherical surface M=1, R, L is the horizontal throw of a P to centre of sphere O and L ∈ [0, CA/2], K are planetary plate rotation and revolution rotating ratio, H is planetary plate height, and α is planetary plate revolution angle, and β is the point initial rotation angle of P and β ∈ [0,2 π], through above-mentioned conversion, for the aspherical elements parameter (CA determined, RoC, M), coating equipment configuration parameter (R, K, H, x _s, y _s, z _s) and evaporation source evaporation characteristic parameter n, utilize and thickness expression formula (1) is transformed rectangular coordinate system, the thickness of above-mentioned formula (1) is converted into independent variable(s) (L, β, function t (L α), β, α), when after revolution certain angle, the thickness of some P is t (L, β, α) integration to α, be

$t(L,\mathrm{\&beta;})=\underset{0}{\overset{2\mathrm{\&pi;F}}{\&Integral;}}t(L,\mathrm{\&beta;},\mathrm{\&alpha;})\mathrm{d\&alpha;}---\left(7\right)$

Wherein F is the revolution number of turns, and (L, β) determines the position of a P on aspherical elements, and t (L, β) determines the film thickness distribution on whole aspherical elements;

(2) add from shade corrected parameter E (L, β, α):

Convex spherical element from shade corrected parameter be:

For concave spherical surface element, the z on the straight line of tie point P and evaporation source S _b1 B (x of=H _b, y _b, z _b) coordinate be:

$\left\{\begin{array}{c}{x}_b=(x-x_s)(H-z_s)/(z-z_s)+x_s\\ y_b=(y-y_s)(H-z_s)/(z-z_s)+y_s\\ z_b=H_b\end{array}\right.---\left(9\right)$

This point is to clear aperture center (x _o, y _o, H) distance be then

$E(L,\mathrm{\&beta;},\mathrm{\&alpha;})=\left\{\begin{array}{cc}1,& d\&le;\mathrm{CA}/2\\ 0,& d>\mathrm{CA}/2\end{array}\right.---\left(10\right)$

Now thickness is film thickness when not adding modifying mask, spherical optics element being put P, and the thickness of formula (7) becomes:

$t(L,\mathrm{\&beta;})=\underset{0}{\overset{2\mathrm{\&pi;F}}{\&Integral;}}t(L,\mathrm{\&beta;},\mathrm{\&alpha;})E(L,\mathrm{\&beta;},\mathrm{\&alpha;})\mathrm{d\&alpha;}---\left(11\right)$

Calculate the some thickness of different positions, obtain spherical optics element without film thickness distribution during baffle plate;

(3) distribute by the theoretical distribution compared without thickness on spherical optics element during modifying mask determine the evaporation characteristic n of evaporation source with experiment:

Perforate in the radial direction on the fixture with the radius-of-curvature identical with spherical optics element and clear aperture, bare substrate is placed in different radial positions, this fixture is arranged on planetary plate center and does substrate, in without modifying mask situation, optical thin film is coated with according to the actual processing condition being coated with optical thin film, film thickness measuring is carried out to the substrate of each plated film, the thickness of optical element corresponding position is represented with on-chip thickness, after drawing out actual thickness distribution curve, with the evaporation characteristic n value of evaporation source for the theoretical film thickness distribution curve calculated by formula (11) and actual thickness distribution curve use method of least squares to carry out matching by variable, n value when objective function is minimum value, be the evaporation characteristic n value in actual evaporation source,

(4) shape and the position of the modifying mask of the optical element film coated homogeneity of planetary rotation system coating equipment Internal Spherical Surface is determined:

Have the plane modifying mask Mask of parabolic outlines, be fixed in vacuum chamber, the system of equations undetermined of baffle plate profile is:

$\left\{\begin{array}{cc}{y}_{\mathrm{mask}}=a_1{(x_{\mathrm{mask}}+a_2)}^2+a_3& x_{\mathrm{mask}}\&Element;[a_4,a_5]\\ y_{\mathrm{mask}}=a_6{(x_{\mathrm{mask}}+a_7)}^2+a_8& x_{\mathrm{mask}}\&Element;[a_4,a_5]\\ x_{\mathrm{mask}}=a_4& \\ x_{\mathrm{mask}}=a_5& \end{array}\right.---\left(12\right)$

Wherein, (x _mask, y _mask) be the coordinate that baffle plate skeletal lines is put, (a ₁, a ₂, a ₃, a ₄, a ₅, a ₆, a ₇, a ₈) be the undetermined parameter of equation undetermined, y _mask=a ₁(x _mask+ a ₂) ²+ a ₃x _mask∈ [a ₄, a ₅] and y _mask=a ₆(x _mask+ a ₇) ²+ a ₈x _mask∈ [a ₄, a ₅] represent two para-curves, x _mask=a ₄and x _mask=a ₅represent two straight lines, these four lines surround an enclosed region Ar and baffle area, and height of baffle plate is H _m, the straight line of tie point P and evaporation source S is being highly z _m=H _m1 D (x at place _m, y _m, z _m) coordinate be:

$\left\{\begin{array}{c}{x}_m=(x-x_s)(z_m-z_s)/(z-z_s)+x_s\\ y_m=(y-y_s)(z_m-z_s)/(z-z_s)+y_s\\ z_m=H_m\end{array}\right.---\left(13\right)$

As a D (x _m, y _m, z _m) in above-mentioned baffle area Ar time, i.e. during the straight-line pass baffle area Ar of tie point P and evaporation source S, vapor molecule is corrected plate washer and blocks, N (L, β, α)=0; As a D (x _m, y _m, z _m) when above-mentioned baffle area Ar is outer, vapor molecule is not corrected plate washer and blocks, N (L, β, α)=1; The thickness of above-mentioned plane modifying mask is adopted to be:

$t(L,\mathrm{\&beta;})=\underset{0}{\overset{2\mathrm{\&pi;F}}{\&Integral;}}t(L,\mathrm{\&beta;},\mathrm{\&alpha;})E(L,\mathrm{\&beta;},\mathrm{\&alpha;})N(L,\mathrm{\&beta;},\mathrm{\&alpha;})\mathrm{d\&alpha;}---\left(14\right)$

At L ∈ [0, CA/2], calculate the thickness at different positions place on aspherical elements in β ∈ [0,2 π] scope, obtain the thickness t of thickest point _max, on aspherical elements, the relative thickness at different positions place is

$\mathrm{Relt}(L,\mathrm{\&beta;})=\frac{t(L,\mathrm{\&beta;})}{t_{\max }},L\&Element;[0,\mathrm{CA}/2],\mathrm{\&beta;}\&Element;\left[\mathrm{0,2}\mathrm{\&pi;}\right]---\left(15\right)$

The relative thickness Relt at thickness the thinnest some place on aspherical elements _minbe the plated film homogeneity of aspherical elements, use Merit is target equation

Merit＝100％-Relt _min(16)

Use the Optimization Toolbox of Matlab software, for baffle plate equation parameter (a simultaneously ₁, a ₂, a ₃, a ₄, a ₅, a ₆, a ₇, a ₈) and height of baffle plate H _minput initial parameter, the uniformity requirement Merit determined with is target equation use computer optimization baffle plate equation parameter (a ₁, a ₂, a ₃, a ₄, a ₅, a ₆, a ₇, a ₈) and height of baffle plate H _m, obtain shape and the position of baffle plate;

(5) when the homogeneity when use baffle plate is optimized does not reach necessary requirement, add a baffle plate, different equation parameters is adopted from first baffle plate, more equation parameter is provided to be optimized, one is added again as do not reached uniformity requirement, by that analogy, till aspherical elements plated film homogeneity reaches requirement.

2. the plate design method improving spherical optics element plated film homogeneity according to claim 1, is characterized in that: in described step (3), testing plate measured film thickness method adopts light-intensity method or Ellipsometric.

3. the plate design method improving spherical optics element plated film homogeneity according to claim 1, is characterized in that: use the method for calculation of computer optimization baffle plate equation parameter for simulated annealing or genetic algorithm in described step.