CN1718844A - The modification method of evenness of film thickness of electron beam evaporation film coating - Google Patents

Abstract

A kind of modification method of evenness of film thickness of electron beam evaporation film coating is promptly revised the method for design of baffle plate, comprises the following steps: the first step: according to the actual disposition situation of vacuum chamber, write out r, cos θ, the expression formula of cos φ; Second step: draw theoretical film thickness distribution curve; The 3rd step: the evaporation characteristic n of actual coating materials is determined in experiment; The 4th step: the position of determining to revise baffle plate; The 5th step: the shape of design modification baffle plate.Our experiments show that: the inventive method can be designed the correction baffle plate rapidly and accurately, can improve the optical film thickness homogeneity greatly.

Description

The modification method of evenness of film thickness of electron beam evaporation film coating

Technical field

The present invention relates to optical thin film, particularly a kind of modification method of evenness of film thickness of electron beam evaporation film coating.

Background technology

Optical film technique is as the important component part of modern science and technology, and the every aspect of people's lives has been contained in its application, has greatly improved, improved people's life.Optical thin film element gives optical element various use propertieies, and the quality of opticinstrument is played important even conclusive effect.Optical film technique is in the status and the effect of optical field, and any other technology can not replace.Optical thin film is widely used in broad field such as daily life, industry, agricultural, building, communications and transportation, medical science, uranology, military and space.Can be with the effect that in short summarize optical thin film: conveniently there be the shadow of optical thin film on every ground that light arranged.

Optical thin film is as a kind of industry, in the practical optical thin film production process, will inevitably run into consider in the Design Theory less than problem, wherein the thickness evenness of optical thin film is the most outstanding one.So-called optical film thickness homogeneity is meant a kind of character that the thickness of optical thin film changes along with the variation of chucking surface position.In the plated film of reality is produced, require on anchor clamps, to place substrate as much as possible, the optical thin film that is coated with simultaneously reaches specification of quality simultaneously.But because system configuration and evaporation source evaporation characteristic, to be deposited to the thickness of coating materials be incomplete same at the different positions place on the anchor clamps, and in order to improve industrialization plated film efficient, it is not all right only utilizing the natural homogeneity of system.In order to improve the homogeneity of vacuum chamber, normally in vacuum chamber, increase and revise the thickness evenness that baffle plate improves optical thin film.

Traditional optical film thickness homogeneity correction generally utilizes baffle plate to finish by testing repeatedly, local many retainings of optically thin thickness a bit in same cover, thin place keeps off a bit not even retaining less, but this method exists very big randomness, need experiment repeatedly constantly, constantly prune baffle plate and can solve the homogeneity of film thickness, as seen the inhomogeneity method of this correction does not have the essence of real assurance homogeneity question, has increased the labor capacity and the cost of dealing with problems widely.

Summary of the invention

The purpose of this invention is to provide a kind of modification method that solves evenness of film thickness of electron beam evaporation film coating, reach and revise the optical film thickness homogeneity rapidly and accurately.

Technical solution of the present invention is as follows:

A kind of modification method of evenness of film thickness of electron beam evaporation film coating is promptly revised the method for design of baffle plate, it is characterized in that this method comprises the following steps:

The first step: according to the actual disposition situation of vacuum chamber, write out r, cos θ, the expression formula of cos φ

Actual disposition situation according to vacuum chamber: the height h of the kind of anchor clamps, anchor clamps, electron beam evaporation source are from the distance L of turning axle, write out r, cos θ, the geometric relationship of cos φ and R, the function expression of u, here θ represents the surface normal of evaporation source and the angle that evaporation source is followed P point line on the anchor clamps, φ represents P point place's surface normal and the evaporation source angle with P point line, r represents the distance that P is ordered on evaporation source and the anchor clamps, R represents that the P point is to the distance of anchor clamps turning axle on the anchor clamps, and u represents the angle of anchor clamps rotation;

Second step: draw theoretical film thickness distribution curve

The geometric relationship substitution following formula of the vacuum chamber that the first step is definite:

$t\left(R\right)=\frac{C}{2\mathrm{\π}}{\∫}_0^{2\mathrm{\π}}\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}$

Compose different values for evaporation characteristic n, draw out theoretical film thickness distribution curve;

The 3rd step: the evaporation characteristic n that determines actual coating materials

Blank substrate is placed in the position of the different radii from the anchor clamps center to the edge, be coated with optical thin film according to actual processing condition when being coated with optical thin film, to each the substrate of plated film carry out film thickness measuring, draw out actual thickness distribution curve, actual thickness distribution curve and theoretical film thickness distribution curve are compared, determine the evaporation characteristic n value of actual coating materials;

The 4th step: the position of determining to revise baffle plate

According to the practical situation of vacuum chamber, select one to be convenient to the fixing position of revising baffle plate, promptly determine to revise the baffle plate medullary ray and follow angle α between the vacuum chamber bottom center line at projection on the vacuum chamber bottom surface and evaporation source;

The 5th step: the shape of design modification baffle plate

Introduce and revise baffle plate function f (R, α δ), adds that under anchor clamps correction baffle plate mera rotates to this place and do not have the coating materials deposit, so should locate f (R, α δ)=0, does not add the local coating materials of revising baffle plate and will have no to be deposited in the substrate with hindering, so should locate f (R, α, δ)=1, revise the size of baffle plate and determined by following formula:

${\∫}_0^{(\mathrm{\α}-\mathrm{\δ}/2)}\frac{\mathrm{co}{s}^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}+{\∫}_{(\mathrm{\α}+\mathrm{\δ}/2)}^{2\mathrm{\π}}\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}={\left({\∫}_0^{2\mathrm{\π}}\frac{\mathrm{co}{s}^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}\right)}_{\min }$

In the formula: δ represents to revise baffle plate in the angle that the R place should keep off, and gets R _Min≤ R≤R _Max, be spaced apart 10mm, according to the δ data that following formula programs and calculates a series of correspondences, draw the shape of revising baffle plate and also make required correction baffle plate;

The 6th step: should revise baffle plate and be installed in described anchor clamps below by design attitude.

When described anchor clamps are the plane rolling clamp, described r, cos θ, the expression formula of cos φ is:

$\left\{\begin{array}{c}{r}^2=h^2+L^2+R^2-2\×R\×L\×\cos u\\ \cos \mathrm{\θ}=\cos \mathrm{\φ}=\frac{h}{r}\end{array}\right..$

Described anchor clamps are the sphere rolling clamp, described r, and cos θ, the expression formula of cos φ is:

$\left\{\begin{array}{c}{r}^2=h^2+{(L+R)}^2-4\×L\×R\×{\sin }^2\left(\frac{u}{2}\right)\\ \cos \mathrm{\θ}=\frac{h}{r}\\ \cos \mathrm{\φ}=\frac{h\sqrt{{\mathrm{\ρ}}^2-R^2}+R(R+L\×\cos u)}{\mathrm{\ρ}\×r}\end{array}\right.$

In the formula: ρ is the spherical radius of sphere rolling clamp.

The inventive method has overcome unstable and the randomness in the former correction optical film thickness homogeneity, our experiments show that: the inventive method can be designed the correction baffle plate rapidly and accurately, improves the optical film thickness homogeneity greatly.

Description of drawings

Fig. 1 is the geometric relationship figure of evaporation source and anchor clamps

Fig. 2 is the geometric relationship figure of evaporation source and plane rolling clamp

Fig. 3 is the geometric relationship figure of evaporation source and sphere rolling clamp

Fig. 4 is correction baffle shapes of the present invention and location diagram thereof

Fig. 5 is the theoretical film thickness distribution graphic representation of the embodiment of the invention

Fig. 6 is the actual thickness scatter chart of the embodiment of the invention

Fig. 7 is that embodiment of the invention correction baffle plate is to the synoptic diagram that blocks on the clamping apparatus disk

Fig. 8 adds to revise optical thin film film thickness distribution curve behind the baffle plate and the comparison diagram that does not add film thickness distribution curve when revising baffle plate

Embodiment

The invention will be further described below in conjunction with embodiment and accompanying drawing.

The present invention program according to as follows:

Ubiquitous problem during thickness evenness is produced as optical thin film, it is a lot of to influence the inhomogeneity factor of optical film thickness, but can be summed up as two aspects generally speaking:

1, the geometric configuration of vacuum chamber departs from the distance of vacuum chamber central shaft, the height of anchor clamps, system factors such as the shape of anchor clamps as electron beam evaporation source.

2, the evaporation characteristic of evaporation source, with the kind of material, the vaporous parameter during plated film, it is relevant that operator operate the factors such as mode of electron beam evaporation source.

Can be divided into two classes to evaporation source in theory: have the some evaporation source of identical evaporation characteristic and satisfy the face evaporation source of cosine relation to all directions evaporation characteristic to all directions.But actual evaporation source is not neither ideal point evaporation source is again the face evaporation source, can be write as for the evaporation characteristic of electron beam evaporation source commonly used: cos ⁿThe form of θ, wherein n represents the evaporation characteristic of evaporation source.Then the optical film thickness that any P is ordered on the anchor clamps can be expressed as:

$t_P=C\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}---\left(1\right)$

C represents constant in the formula, and θ represents the surface normal of evaporation source 1 and evaporation source 1 angle with P point line on the anchor clamps 2, and φ represents P point place's surface normal and evaporation source 1 angle with P point line; R represents the distance of any point P on evaporation source 1 and the anchor clamps 2, and n represents the evaporation characteristic of evaporation source.Geometric relationship as shown in Figure 1.

In order to improve the thickness evenness of optical thin film, mostly adopt rotary jig now, so have identical optical film thickness to the equidistant point of turning axle on the anchor clamps.Then any P of the rolling clamp blooming of ordering can be represented with following formula:

$t\left(R\right)=\frac{C}{2\mathrm{\π}}{\∫}_0^{2\mathrm{\π}}\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}---\left(2\right)$

R represents that the P point is to the distance of anchor clamps turning axle on the anchor clamps in the following formula, and u represents the angle of anchor clamps rotation.For difform rolling clamp, according to geometric relationship r, cos θ, cos φ can be expressed as R, the function of u.

If on the rolling clamp to turning axle distance different radially have an identical thickness evenness, then whole anchor clamps have equal optical film thickness.

The inventive method or rather, is the design of revising baffle plate, and process is as follows:

The first step: write out r, cos θ, the expression formula of cos φ

Actual disposition situation according to vacuum chamber, determine the geometric parameter that influences film uniformity, the kind (as plane rolling clamp, sphere rolling clamp etc.) that comprises anchor clamps, the height h of anchor clamps, arrive the ultimate range Rmax of rotation axis on the anchor clamps, electron beam evaporation source leaves the distance L of turning axle, the spherical radius ρ of sphere rolling clamp.And write out r, cos θ, the expression formula of cos φ according to geometric relationship.Plane rolling clamp 3 as shown in Figure 2, sphere rolling clamp 4 as shown in Figure 3, wherein the O point is the sphere centre of sphere, OP is spherical radius ρ.

Have for the plane rotating clamp: $\left\{\begin{array}{c}{r}^2=h^2+L^2+R^2-2\×R\×L\×\cos u\\ \cos \mathrm{\θ}=\cos \mathrm{\φ}=\frac{h}{r}\end{array}\right.$

Rotation accompanies to sphere: $\left\{\begin{array}{c}{r}^2=h^2+{(L+R)}^2-4\×L\×R\×{\sin }^2\left(\frac{u}{2}\right)\\ \cos \mathrm{\θ}=\frac{h}{r}\\ \cos \mathrm{\φ}=\frac{h\sqrt{{\mathrm{\ρ}}^2-R^2}+R(R+L\×\cos u)}{\mathrm{\ρ}\×r}\end{array}\right.$

Second step: draw theoretical film thickness distribution curve

Bring the vacuum chamber geometric relationship formula that the first step is determined into top (2) formula, n in the actual evaporation source film thickness distribution formula (2) is composed different values, general n is spaced apart 0.2 and gets final product between 1～2, draws out the film thickness distribution curve under the different in theory evaporation characteristics.As shown in Figure 5.

The 3rd step: the evaporation characteristic n value of determining actual coating materials

From the anchor clamps center the same footpath to edge upwards place blank substrate, be coated with optical thin film according to actual processing condition when being coated with optical thin film, draw out the optical thin film film thickness distribution curve that is coated with.As shown in Figure 6.To be coated with optical thin film film thickness distribution curve and theoretical film thickness distribution curve compares, determine the evaporation characteristic n value of actual coating materials.We just can determine optical thin film actual (real) thickness distribution formula exactly like this, make the optical film thickness correction that foundation accurately arranged, and have solved the randomness in the common correction homogeneity process.

Found a kind of method of definite actual coating materials evaporation characteristic by this step, the thickness distribution formula of the actual like this optical thin film that is coated with has just been determined exactly, has guaranteed the accuracy of following design homogeneity correction baffle plate.

The 4th step: determine to revise the position of baffle plate, promptly revise the baffle plate medullary ray and follow angle α between the vacuum chamber bottom center line at projection on the vacuum chamber bottom surface and evaporation source

Because the correction baffle plate of design is relevant with the position of its placement, so at first will determine under anchor clamps, where to place the correction baffle plate before the design.According to the practical situation of vacuum chamber, select a position of being convenient to stationary fixture, the correction baffle plate energy level that makes design is near the anchor clamps below.Measure the angle α that the medullary ray 6 of revising baffle plate 5 is followed between the vacuum chamber bottom center line 8 at projection on the vacuum chamber bottom surface 7 and evaporation source 1, as shown in Figure 4.The rotary-type anchor clamps in box plane shown in Figure 4 (3) coating equipment correction baffle plate is placed situation.

The 5th step: calculate the shape of revising baffle plate

Do not add when revising baffle plate 5, it is the thinnest place of optical thin film that a place is arranged on the anchor clamps, as long as add the correction baffle plate in thicker place, makes that the thinnest place equates to get final product when adding the thickness of revising this place's optical thin film behind the baffle plate and not adding the correction baffle plate.For this reason we introduced one revise the baffle plate function f (R, α δ), revise the size of baffle plate 5 and can determine by following formula:

${\∫}_0^{2\mathrm{\π}}\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}\×f(R,\mathrm{\α},\mathrm{\δ})}{r^2}\mathrm{du}={\left({\∫}_0^{2\mathrm{\π}}\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}\right)}_{\min }---\left(3\right)$

Above (3) formula the right thickness of optical thin film thinnest part on the anchor clamps when revising baffle plate 5 for not adding, we do not add baffle plate at this place like this, and are the reference position with it.The following formula left side represents that the place that optical thin film is thicker on the anchor clamps 3 will add the correction baffle plate, and makes and add and revise the thickness that the thickness of optical thin film behind the baffle plate equals not add thinnest part when revising baffle plate, promptly above the right item of formula.

(3) R represents that different positions is to the distance of anchor clamps turning axle on the anchor clamps in the formula, and α represents to revise the position that the baffle plate medullary ray is placed, and δ represents to revise the angle that baffle plate falls at R place retaining.Owing to add that under anchor clamps revising the baffle plate mera rotates to this place and do not have the coating materials deposit, thus should the f of place (R, α δ)=0, do not add the local coating materials of revising baffle plate and will have no the ground of obstruction and be deposited in the substrate, thus be somebody's turn to do locate f (R, α, δ)=1.

Calculate the δ of different R correspondences for convenience, (4) formula below (3) formula is reduced to.Get R _Min≤ R≤R _Max, be spaced apart 10mm, according to (4) formula program can calculate for δ.

${\∫}_0^{(\mathrm{\α}-\mathrm{\δ}/2)}\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}+{\∫}_{(\mathrm{\α}+\mathrm{\δ}/2)}^{2\mathrm{\π}}\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}={\left({\∫}_0^{2\mathrm{\π}}\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}\right)}_{\min }---\left(4\right)$

Angle of spread δ according to different correction baffle plate radius R correspondences just can make revising baffle plate.

Be example design modification baffle plate homogeneity now with the ZZS-660 coating equipment:

The first step:

This coating equipment is the plane rolling clamp, and structure as shown in Figure 2.The geometric parameter of vacuum chamber: electron beam evaporation source 1 is L=240mm from vacuum chamber central shaft distance, the height h=335mm of anchor clamps 3, and the maximum radius of clamping apparatus disk is R _Max=250mm.The geometric relationship of vacuum chamber is:

$\left\{\begin{array}{c}{r}^2=h^2+L^2+R^2-2\×R\×L\×\cos u={335}^2+{240}^2+R^2-2\×240\×R\×\cos u\\ \cos \mathrm{\θ}=\cos \mathrm{\φ}=\frac{h}{r}=\frac{335}{{({335}^2+{240}^2+R^2-2\×335\×R\×\cos u)}^{\frac{1}{2}}}\end{array}\right.$

Wherein R represents that different positions is to the distance of turning axle on the anchor clamps, and u is the angle that anchor clamps rotate.

Second step:

The geometric relationship formula that the last step is determined is brought into blooming distribution formula (2), make the corresponding theoretical film thickness distribution curve of optical thin film of different evaporation characteristic n values (1≤n≤2, interval 0.2) as shown in Figure 5, among the figure: the 9-reference line, the film thickness distribution curve of 10-evaporation characteristic n=1, the film thickness distribution curve of 11-evaporation characteristic n=1.2, the film thickness distribution curve of 12-evaporation characteristic n=1.4, the film thickness distribution curve of 13-evaporation characteristic n=1.6, the film thickness distribution curve of 14-evaporation characteristic n=1.8, the film thickness distribution curve of 15-evaporation characteristic n=2.0.

The 3rd step:

Do experiment and determine the relative thickness distribution curve of the actual optical thin film that is coated with, and with the different evaporation characteristics of last step Theoretical Calculation under the relative thickness distribution curve compare, according to the evaporation characteristic n value of relatively determining actual evaporation source of experiment thickness distribution curve and theoretical curve.Fig. 6 is twice experiment in a front and back thickness distribution curve, wherein tests for the first time thickness distribution curve 16, tests thickness distribution curve 18, twice empirical average thickness distribution curves 17 for the second time.The coating materials evaporation characteristic n=1.2 of this coating equipment with theoretical film thickness distribution curve ratio among twice experiment thickness distribution curve 17 and Fig. 6, as can be known.

The 4th step:

Consider the practical situation of vacuum chamber, at this we ° to locate with α=110 be the placement location of baffle plate, and as the initial designs position of baffle plate medullary ray.

The 5th step: the size shape of calculation Design correction baffle plate

Calculate different radii R place according to (4) formula and revise the angle δ that baffle plate keeps off, draw and revise on 19 pairs of clamping apparatus disks of baffle plate 20 block as shown in Figure 7, wherein a=110 °, 120mm≤R≤240mm.

Add and revise optical thin film film thickness distribution curve (21) behind the baffle plate and the contrast that does not add film thickness distribution curve (22) when revising baffle plate as shown in Figure 8 that film uniformity is improved as 1.1% by not adding 11.7% when revising baffle plate.

Claims (3)

1, a kind of modification method of evenness of film thickness of electron beam evaporation film coating is characterized in that this method comprises the following steps:

The first step: according to the actual disposition situation of vacuum chamber, write out r, cos θ, the expression formula of cos φ

Actual disposition situation according to vacuum chamber: the height h of the kind of anchor clamps, anchor clamps, electron beam evaporation source are from the distance L of turning axle, write out r, cos θ, the geometric relationship of cos φ and R, the function expression of u, here θ represents the surface normal of evaporation source and the angle that evaporation source is followed P point line on the anchor clamps, φ represents P point place's surface normal and the evaporation source angle with P point line, r represents the distance that P is ordered on evaporation source and the anchor clamps, R represents that the P point is to the distance of anchor clamps turning axle on the anchor clamps, and u represents the angle of anchor clamps rotation;

Second step: draw theoretical film thickness distribution curve

The geometric relationship substitution following formula of the vacuum chamber that the first step is definite:

$t\left(R\right)=\frac{C}{2\mathrm{\π}}{\∫}_0^{2\mathrm{\π}}\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}$

Compose different values for evaporation characteristic n, draw out theoretical film thickness distribution curve;

The 3rd step: the evaporation characteristic n that determines actual coating materials

Blank substrate is placed in the position of the different radii from the anchor clamps center to the edge, be coated with optical thin film according to actual processing condition when being coated with optical thin film, to each the substrate of plated film carry out film thickness measuring, draw out actual thickness distribution curve, actual thickness distribution curve and theoretical film thickness distribution curve are compared, determine the evaporation characteristic n value of actual coating materials;

The 4th step: the position of determining to revise baffle plate

According to the practical situation of vacuum chamber, select one to be convenient to the fixing position of revising baffle plate, promptly determine to revise the baffle plate medullary ray and follow angle α between the vacuum chamber bottom center line at projection on the vacuum chamber bottom surface and evaporation source;

The 5th step: the shape of design modification baffle plate

Introduce and revise baffle plate function f (R, α δ), adds that under anchor clamps correction baffle plate mera rotates to this place and do not have the coating materials deposit, so should locate f (R, α δ)=0, does not add the local coating materials of revising baffle plate and will have no to be deposited in the substrate with hindering, so should locate f (R, α, δ)=1, revise the size of baffle plate and determined by following formula:

${\∫}_0^{(\mathrm{\α}-\mathrm{\δ}/2)}\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}+{\∫}_{(\mathrm{\α}+\mathrm{\δ}/2)}^{2\mathrm{\π}}\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}={\left({\∫}_0^{2\mathrm{\π}}\frac{{\cos }^n\mathrm{\θ}\cos \mathrm{\φ}}{r^2}\mathrm{du}\right)}_{\min }$

In the formula: δ represents to revise baffle plate in the angle that the R place should keep off, and gets R _Min≤ R≤R _Max, be spaced apart 10mm, according to the δ data that following formula programs and calculates a series of correspondences, draw the shape of revising baffle plate and also make required correction baffle plate;

The 6th step: should revise baffle plate and be installed in described anchor clamps below by design attitude.

2, the modification method of evenness of film thickness of electron beam evaporation film coating according to claim 1 is characterized in that described anchor clamps are the plane rolling clamp, described r, and cos θ, the expression formula of cos φ is:

$\left\{\begin{array}{c}{r}^2=h^2+L^2+R^2-2\×R\×L\×\cos u\\ \cos \mathrm{\θ}=\cos \mathrm{\φ}=\frac{h}{r}\end{array}\right..$

3, the modification method of evenness of film thickness of electron beam evaporation film coating according to claim 1 is characterized in that described anchor clamps are the sphere rolling clamp, described r, and cos θ, the expression formula of cos φ is:

$\left\{\begin{array}{c}{r}^2=h^2+{(L+R)}^2-4\×L\×R\×{\sin }^2\left(\frac{u}{2}\right)\\ \cos \mathrm{\θ}=\frac{h}{r}\\ \cos \mathrm{\φ}=\frac{h\sqrt{{\mathrm{\ρ}}^2-R^2}+R(R+L\×\cos u)}{\mathrm{\ρ}\×r}\end{array}\right.$

In the formula: ρ is the spherical radius of sphere rolling clamp.

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