JPS5972010A - Film thickness monitoring device of optical film forming device - Google Patents

Abstract

PURPOSE:To perform monitoring even when a base twists or oscillates and when the monitor surface cause diffused reflection by using an optical fiber bundle for either the optical path from a projector to the base or the optical path from the base to a photodetector. CONSTITUTION:Incident light from the projection 19a is reflected by a semitransparent mirror 27, condensed by a condenser 24, and projected on a monitor surface 28 through the optical fiber bundle 23. Its reflected light traverses backward to enter the photodetector 20a through the semitransparent mirror 27. Its output is sent to a recorder 26 through an amplifier 25. Since the optical fiber bundle 23 and condenser lens 24, the incidence optical path Iu coincides with the reflection optical path Ru and the monitoring is possible even when the monitor surface 28 twists or oscillates and when the monitor surface causes diffusion.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention involves forming an optical film on the surface of a long sheet-like substrate, and then projecting light from a projector onto the substrate, transmitting the light through the substrate, or receiving the light after being reflected by the substrate. A device for monitoring the thickness of an optical film based on the characteristics of the light received by the device has been known for some time, for example, as shown in FIG. be done. In this figure, a long sheet-like substrate is unwound from an unwinding roller l in a 10 vacuum chamber/l, and several unwinding-side deflection rollers 13 are unrolled.
After being deflected and guided by the cooling cylinder 15, it advances under the cooling cylinder 15 while contacting it, and then is deflected and guided by the winding cylinder 15, and then is deflected and guided by the winding cylinder 15, and then is deflected and guided by the winding roller 15. It is wound up. Seven evaporation sources /7a, /7b are arranged in the lower blade of the cooling cylinder /lI-, and the evaporation sources /'
7a.

The deposits A and B heated in /'lb evaporate from this n, fly in a vacuum atmosphere, and deposit in the form of a film on the surface of the substrate /θ to form an optical film. An optical monitor/g is used as a film thickness monitoring device, which has a light projector and a light receiver. The emitter consists of a light source such as a W lamp or a halogen lamp, and a collimator, and the receiver consists of a photodetector such as a photomultiplier or PBS that converts light into an electrical signal, and a narrow band filter. Amplifiers and other devices are connected to each other. In the case of utilizing light reflection, the light emitter /qa and the light receiver 20a are generally formed integrally as a light emitter/receiver, and the light beam emitted from the emitter/qa and the winding side deflecting roller 15a and /Sb which constitute the guide members are emitted from the light emitter/qa and the light receiver 20a. The light is projected onto the substrate io in the area between, is reflected by the substrate 10, and then returns to the emitter/receiver.

When utilizing transmission of light, the emitter/91) and the receiver 20b are usually separated and distributed, and the emitter/? Light from b! ili! For example, after being reflected by a reflecting mirror 2/, the light passes through the base IO and reaches the light receiver Ob. Light receiver 20
The thickness of the optical film can be monitored based on the characteristics of the light received by the light beams a, 20b, and the details can be found in, for example, JP-A-3.
2-79933, so the explanation will be omitted.

The arrangement described above in principle ensures that film thickness monitoring is achieved with high precision, as is well known to those skilled in the art. In reality, the deflection rollers 15a and /3
Even if the base body 10 is sufficiently stretched in the area between b and b, the base body 10 may twist or vibrate by an angle, for example, from the designed position, as shown by the broken line 10D in Figure 1. When using the reflection of light, for example, in principle, the reflected light R that should return along the optical path of the light beam projected from the light emitter/receiver /?a, or the light beam incident on the substrate. is actually deflected to the side from the optical path of the incident light. Therefore, if the twist angle, that is, the deflection angle is large, the reflected light R will not reach the emitter/receiver /9a, and the light beam will not arrive at the emitter/receiver /9a, Even if the film thickness is small, it is of course not constant but fluctuates, so the amount of reflected light arriving at the emitter and receiver will fluctuate, making it difficult or impossible to monitor the film thickness. When the distance between the surface of the formed substrate io) and the emitter /' is just ON, and the diameter of the incident light beam is 10, the twist j, angle is 0, and angle is 0.
If the amount exceeds that level, the reflected light R [completely deviates from the light receiver 0]. Obviously, something similar occurs when using light transmission.

The above-mentioned drawbacks of the prior art include that instead of projecting light onto the substrate IO in the region between the winding side deflection rollers 15a and /sb of the guide member 15ai, the portion of the substrate that contacts the guide member V'115b; It seems that if the light is projected onto the base part, it will not twist or vibrate, so it can be eliminated.

However, if this is done, this base portion will curve along the guide member /S instead of spreading out in a plane like the area between the two guide members (Fig. 3).
It has the effect of diverging light, so that the incident light beam projected onto the base part along the incident light path uK diverges as indicated by Ru after being reflected at the base part. Therefore, the emitted light R almost never reaches the photoreceiver KO (FIG. 1), so that film thickness monitoring cannot be achieved. The guide member is made of a transparent material [,
The same thing can be said when the transmission of light is utilized.

Furthermore, conventional film thickness monitoring devices cannot be used if the weight of the incident light is diffusely reflected by the monitoring surface and most of it does not reach the receiver; Conventional film thickness monitoring devices also cannot be used if a monitoring window for passing reflected or transmitted light is not placed in a suitable location, or if there is not enough space for an optical system such as a reflector 21.

Therefore, the main purpose of the present invention is to eliminate the drawbacks of the film thickness monitoring device in the conventional optical film forming apparatus. In a more conventional film thickness monitoring device, at least a portion of the optical path from the emitter to the substrate and the optical path from the substrate to the receiver, both of which are near the substrate, is formed by an optical fiber bundle.

According to the ability Q; /15” of the optical path portion whose phase is 11ffl from the optical path portion where the upper phase is constant!
! Optical extension 9. There is a phase separation n from the optical path part, which is a two-phase type "fiber and substance". A branched optical fiber bundle is used, which includes an optical fiber bundle extending to the other side of the optical path part, and an optical path between the bundle and the emitter and an optical path between this and the receiver, or In each case, a condensing optical system such as a condensing lens is arranged.

Embodiments of the present invention will be described in detail below with reference to the drawings.

In the first embodiment shown schematically in the figure, an optical fiber bundle 23 and a condensing lens 2 group as a condensing optical system are provided in the optical path between the first direction rollers /Sa and /Sb and the base body 10. is assigned. Although the optical film i ffj + bundle 23 is shown to have a loop portion, this is merely for clarification, and the loop portion is obviously not a necessary masterpiece. In the detailed description, as shown in No. 5M, it has an optical monitor/gri emitter/9a, a light receiver 20a, and a recorder=6 connected to this light receiver via an amplifier S, and from the light emitter/9a. The luminous flux (incident light) ■ is reflected by the semi-transparent mirror core VC, travels along the optical path Iu, and is reflected by the monitoring surface 'f, that is, the surface cog of the substrate lθ on which the optical film is deposited, The reflected light flux (reflected light) R [proceeds along the optical path Ru, passes through the translucent light, and reaches the light receiver λOa. According to the present invention, the optical fiber bundle 23 and the condensing lens 4 are arranged so that the incident optical path U coincides with the reflected optical path Ru. That is, in the arrangement shown in FIG. 2, the situation is the same as when the wrinkle angle, that is, the deflection angle, is always zero, that is, when there is no wrinkle at all.

On that point, let's talk about Figures 6 and 7! Referring also to FIG. 3, the optical fiber bundle 3 has an inner diameter of, for example,
rnms outer diameter, 0.071 in diameter in 5th grade PVC colored Wa 29! m glass optical 11° several hundred
When the book is bundled and stored, it has 30 optical films/fibers, acceptance angle #: b 7°, numerical aperture 0-3, Xdf overspectrum 0. Gluco, a cow called /μm, has a mirror finish on its end surface. For example, an optical fiber bundle 23 with a length of 100 mm is used, and its inner end 3 is
The six condensing lenses 2q, which are arranged at a slight distance o, /~/mn, from the /Zuba monitoring surface g, are, for example, convex lenses with a diameter of 36 nodes and a focal length of 3θ, and are optical fiber bundles. 2.3 is placed approximately the focal length away from the outer edge 32 of the lens. With such an arrangement, the incident light weight from the projector/qa is e.g.
The light beam of n reaches the condenser lens 2, converges on the outer end 32 of the optical fiber bundle 3, travels through the optical fiber bundle 23, and reaches the inner end 31 thereof. This incident light is at the inner end 3
/ is projected toward the monitoring surface 2g and reflected by it, but as the inner end 31 is located close to the monitoring surface 2g as described above, most of the reflected light R is reflected within the lid. edge 31
, and from there it optically travels back through the bundle 23 to its outer end 32 . The incident light R1-j travels while diverging from the three outer ends, but is converged in parallel by the condenser lens cog, and heads toward the light receiver 20a along the reflected optical path Ru, which substantially coincides with the incident optical path 1u. At this time, the base /θ is twisted
However, as mentioned above, the inner end 31 is monitored,
Since it is located very close to the surface 1g, most of the reflected light also returns to the inner end 3/ and passes through the same path as described above.
From the 9th section, the second fruit shown in diagram */b is 1 in 11 cases.
The emitter/wafer a and the receiver θa are arranged slightly apart from each other, and the monitoring surface 2g of the substrate 10, which has been coated with an optical film but has not yet been separated from the cooling tube/ri, is monitored. Let's do it. Therefore, the inner end 31 of the optical fiber y# bundle 3
is placed in close proximity to the monitoring surface of the straight-curved base body 10 away from the cooling cylinder/da. The optical fiber bundle 23 has a branching part 33, and there are seven fibers, as shown by 3c, extending from the branching part 33 to the inner end 3/4, and extending from the branching part 33 to the outer end U3a.
, -2Jb, it has a structure divided into a light emitting part and a light receiving part. This optical fiber bundle 23 has a light emitting optical fiber JOa and a light receiving optical fiber 30b,
The light projecting optical fiber 30a is the light projecting portion 23 of the optical fiber bundle 3.
The common part 3c passes through the branch part 33 from the outer end 3 pieces a of
Extend to the inner end of 3 threads. Further, the light-receiving optical fiber 30b passes from the outer end 3b of the light-receiving portion 3b, passes through the branching portion 33, and reaches the inner end 3/. Light emitting part 23a and light receiving part, 2
3b, only the light emitting optical fibers 30a or only the light receiving optical strings 30b are bundled together and housed in the colored wagon 9, but in the common part 23c, the light emitting optical fibers 3
0a and optical fiber for light reception, ? The Obs are bundled in a distribution such that they are substantially intermingled with each other and arranged in one color sum 2q. In such an arrangement, the weight of the incident light from the projector/9a is concentrated by the condenser lens 11. a1 optical fiber for light projection 3
A considerable portion of the reflected light R that is incident on the monitoring surface 2g through 0h and reflected from andn passes through the light-receiving optical fiber 30b, the condensing lens 2'' (b), and heads toward the light receiver 20a. Although the monitoring surface g is curved according to the cooling cylinder /4' in the embodiment, since the outer end 31 is located very close to the monitoring surface -g, the monitoring can be carried out reliably. , 1/i%', 3/ of the optical fiber bundle 3) can also be placed close to the monitoring surface 2g of the base portion that contacts other members such as the deflection rollers /SF3., /Sb.

FIG. 17 and FIG. 1g show an embodiment in which the film thickness is monitored using light transmitted through the substrate /θ. The incident light from the projector 1b follows its optical path Iu, passes through a condenser lens and an optical fiber bundle 23, and then heads toward the base io. The transmitted light T transmitted through the base 10 is converged in parallel along the optical path Tu by the T lens 3'l, and then sent to the light receiver U.
(reaches 7b. In this example, the transmitted optical path TuVc
It is clear that an optical lace bundle (not shown) can also be arranged.

In the embodiment shown in FIGS. 6 and 7, for example, a convex lens 3S having a focal point 2Stas is connected to the monitoring surface g and the inner end of the optical fiber bundle 23 in order to avoid the dependence of the reflectance on the monitoring surface 2g on the angle of incidence. 3/ shows a variant placed between.

The distance from the inner end 3/ to the center of the convex lens 35 is 3 and 6.
Also, the distance from the center of this center to the monitoring surface 2g''! is IO, gtnm, and if the half-opening angle is 30° in Figures 6 and 7, this becomes lOo due to the arrangement of the convex lens 3s. However, the dependence of the reflectance on the angle of incidence can be substantially prevented.

In each of the embodiments described above, since the inner end 31 of the optical fiber bundle 23 is arranged near the monitoring surface 2g, according to the present invention, even when light is diffusely reflected on the monitoring surface λg, a large amount of the reflected light is can reach the optical fiber bundle 23, thus achieving film thickness monitoring.

In order to confirm the effects of this invention, we used an apparatus as shown in Fig. 1, and used
A substrate 10 made of M aluminum foil is transported at a speed of 3 M/min, and Cr and (1! During the process of forming the absorbent film, the optical fiber bundle 2
A comparative test was conducted between the case where 3 and the condenser lens 2 were used and the case where they were not used. The specifications, configuration, arrangement, etc. of the optical fiber bundle, condensing lens, optical monitor, etc. are illustrated in the explanation from Figures to Figure 3.
Light with a wavelength of μm was used. The time (T) variation of the output (P) shown on the recorder of the optical monitor was as shown in FIGS. 20 and 21. Here, FIG. 20 shows a case according to this invention using an optical string bundle and a condensing lens.
Figure 20 shows the case of the conventional method that does not use these (however, Figure 20 and Figure 27 show output (P) and time (
The units of T) are different). In this figure,
The Fl-i evaporation work start point and the GVi evaporation work end time are shown, and the chain line U indicates the correct output level when not performing the evaporation operation, and the chain line ■ indicates the correct output level during the evaporation operation, and the chain pl
s indicates the level of reflection 0, that is, the output level when the substrate is excluded. Comparing these drawings, the effectiveness of this invention is clear.

Figure 1 shows seven examples of the results of using transmission according to the embodiments shown in Figures 1 and 1g. Its specifications, configuration, arrangement, working conditions, etc. are similar to those in the first OV except that the base is transparent, but the details will be omitted. Here, the level -F of the transmittance θ, that is, the chain line S indicating the output level when an opaque substrate is used, substantially coincides with the horizontal axis.

Since the film thickness monitoring device according to the present invention is constructed as described above, it has characteristics such as being able to monitor the film thickness even when the substrate is twisted or vibrating, and can also be used on monitoring surfaces that undergo diffuse reflection. However, it can be deployed regardless of the position of the monitoring window, even if there is insufficient space for an optical system, thus eliminating the drawbacks of conventional film thickness monitoring devices. Moreover, the elimination of this drawback can be achieved relatively easily and inexpensively by employing optical fiber bundles and condensing lenses used as necessary.

[Brief explanation of the drawing]

1I'f is an illustrative diagram showing seven examples of a film thickness monitoring device in a conventional optical film forming apparatus; Figure 3 is an illustrative diagram showing a state in which light is projected onto the base portion that contacts the guide member;
No. V is a partial illustrative view corresponding to FIG. 7 schematically showing the first embodiment of the film thickness monitoring device according to the present invention, FIG. 5 is a diagram showing the main part of FIG. Figure 7 is shown in Figure 6 with a black mark 1. FIG. 7 is an enlarged view of the part shown in FIG. Corresponding figure, 2(':
/ / / / /shi Figure 1 θ An enlarged view of the part indicated by KX An enlarged view of the part shown in Figure 13.
Figure 75 - Enlarged view of the part marked XV in Figure 10, ■)
/ 6r5! A sectional view taken along the line XV-XM of Figure 1S, Figure 77 and Figure ig show the third embodiment and example.
Figures P, q and 7 corresponding to Figure 6, f
$: Figure 19 is a modification of Figure 6, Figure 20 is Figure 9.
A graph showing experimental results according to the embodiment shown in the figure, a graph corresponding to FIG. 20 showing experimental results using a conventional apparatus in FIG. 2, and a graph corresponding to FIG. This is a graph corresponding to the figure. On the N plane, /θ is the substrate, 17a and /'7b are evaporation sources for forming an optical film, /9a and /9b are projectors 1 for projecting light, and 20a and 20b are for reflecting light or transmitting light. The receiving optical receiver, the incident optical path, the reflected optical path, Tu
The optical fiber bundle is shown at 23. Figure 1 Figure 4 Figure 5 Figure 21 G J ) 60-

Claims (1)

[Claims] l After an optical film is formed on the surface of a long sheet-like substrate, light is projected onto the substrate from a projector, passes through the substrate, is reflected by the substrate, and is received by a light receiver. In a device that monitors the film thickness of an optical film based on the reliability of the A film thickness monitoring device for an optical film forming bag, characterized in that it is formed by a fiber bundle. 2. The film thickness monitoring device according to claim 7, wherein a common optical fiber bundle is used when both the optical paths are substantially interconnected. (3) When the two optical paths are partially substantially mutually intersecting, (1) an optical path that is separated from the optical fiber and the optical fiber that extends to /7i of the optical path section that is separated from the optical path section that substantially overlaps; Patented 117J song M using a branched optical fiber bundle including an optical fiber extending at the other end of the part.
The thickness monitoring device k described in item 1. Claims (1), (2), and (2) above claim 1, wherein a condensing optical system is disposed between the optical path between the optical fiber bundle and the emitter, and the optical path between the optical fiber bundle and the receiver. The film thickness monitoring device according to any one of Items 3 to 7.