JPH03206906A - Optical film-thickness monitor - Google Patents

Abstract

PURPOSE:To perform the adjusting work for an optical axis highly accurately and simply by arranging a first reticle for confirming the position of the optical axis at the upstream side of a light path from a light receiving surface in the vicinity of the light receiving surface of a photoelectric transducer unit, and arranging a second reticle for confirming the direction of the optical axis at the downstream side of the light path from the first reticle. CONSTITUTION:When an optical axis is adjusted, the coupling of a photoelectric transducer unit 30 and a light path tube 29 is released, and the unit 30 is moved to a standby position. A filter 31 is pulled out of a filter holding frame 32, and a first reticle 34 is mouted in the frame 32. A sheet of monitor glass 15 or an adjusting reflection mirror is loaded in a holder 27. Under this state, a light source 20 emits light, and the detecting light is projected. The direction of the detecting light is changed with a mirror 24, and the light is projected on the monitor glass 15. A part of the light is reflected and reaches a mirror 25. The mirror 25 deflects the reflected light to the unit 30. The reflected light is transmitted through the reticle 34 and reaches a second reticle 35. The adequacy of the position and the direction of the center of the optical axis of the reflected light is judged based on the deviating degree between the profile line of the light and an index line when the light transmits through the reticles 34 and 35.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical film thickness monitor that measures the film thickness of a film-forming substrate in real time in a vacuum evaporation apparatus.

(Prior Art) As a conventional device of this type, a film thickness monitor shown in FIG. 2 is known. This includes a floodlight 16, a mirror box 17,
It consists of a light receiver 18 and a measuring instrument body (not shown), and as shown in FIG.
5 is irradiated with detection light, and a change in the amount of reflected light from the monitor glass 15 is detected by a light receiver 18 to measure the film thickness. Film thickness monitors that detect changes in the amount of transmitted light instead of detecting changes in the amount of reflected light are also known.

In the film thickness monitor, only monochromatic light of a specific wavelength out of the light reflected from the monitor glass 15 is introduced into the light receiver 18 through a filter, and is photoelectrically converted to measure the film thickness.

At this time, the reflectance of monochromatic light continuously increases and decreases in a sine curve shape as the film thickness increases. In other words, the reflectance (reflected light amount) is maximum when the film thickness is an integral multiple of a half wavelength of monochromatic light (including zero), and the minimum reflectance is when the film thickness is an integral multiple of a quarter wavelength of monochromatic light. becomes. Incidentally, although the range of change in reflectance depends on the wavelength of monochromatic light, it is about several percent during total reflection.

(Problems to be Solved by the Invention) As described above, the optical film thickness monitor can perform highly accurate film thickness measurement using the interference effect of light. However, since the range of change in reflectance is small, errors are likely to occur due to positional or directional deviations of the reflected light, and precise optical axis adjustment is required. The situation is no different in the case of a transmission type film thickness monitor.

Incidentally, the inside of the vapor deposition tank 1 is frequently cleaned, but during this cleaning work, the mirror box 17 or the like may be mistakenly abutted, and the optical axis may be deviated. In such cases, the optical axis must be adjusted, but conventionally the photoelectric conversion unit of the light receiver 18 had to be removed and the position and direction of the reflected light on the light-receiving surface of the light-receiving element had to be confirmed. The disadvantage was that it required a lot of effort and time. In addition to optical axis adjustment due to such errors, regular optical axis confirmation work is also required, so streamlining the optical axis adjustment work has been strongly desired.

This invention was proposed in view of the above, and by improving the light receiver, it is possible to perform optical axis adjustment work with high precision and ease, and in particular, it improves the film thickness accuracy of optical thin films, and at the same time The purpose is to improve the productivity of vapor deposition equipment.

(Means for Solving the Problems) In the present invention, the photoelectric conversion unit is separably joined to the optical tube, and there are two positions in which the photoelectric conversion unit is joined to the optical tube, and one where it is separated from the optical tube and outside the optical path. The photoelectric conversion unit is guided and supported by a guide means so as to be movable between the standby position and the standby position where the photoelectric conversion unit is evacuated. A reticle was placed, and a second reticle for checking the optical axis direction was placed on the downstream side of the optical path from the first reticle.

In the case where the optical path tube is provided with a filter that allows only measurement light of a specific wavelength to pass through and a filter holding frame that fixes and holds this filter, the structure of the mounting part of the first reticle and the filter should be the same. It is preferable that both members are configured to be replaceable with respect to the filter holding frame.

More preferably, the second reticle is fixedly installed on the downstream side of the optical path from the photoelectric conversion unit in the use position.

(Function) When adjusting and checking the optical axis, the photoelectric conversion unit is separated from the optical path cylinder and moved to a standby position outside the optical path. In this state, both the first and second reticles are arranged perpendicular to the optical axis, and detection light is irradiated from the light projector. Each reticle has an index line formed corresponding to the regular optical axis center position, so by visually checking the position of the light outline on each reticle, the position of the optical axis can be determined using the first reticle. The direction of the optical axis can be easily determined using the second reticle.

As described above, in the film thickness monitor of the present invention, the first and second
You can easily check the position and direction of the optical axis using both reticles, so by adjusting the posture of the reflective mirror in the mirror box and the monitor glass in response to the deviation, the optical axis can be adjusted with high precision and easily. can be done. Also,
Since the photoelectric conversion unit is supported by the guide means so that it can be displaced between the use position and the standby position, the photoelectric conversion unit can be separated and moved out of the optical path and reattached to the optical path tube quickly and with high positional accuracy. This can be done under the

(Embodiment) FIGS. 1 to 4 show an embodiment of a film thickness monitor according to the present invention.

In Fig. 2, numeral 1 is a vacuum evaporation device, 2 is a evaporation tank, and 3 is a vacuum evaporation device.
is a film thickness monitor. A vapor deposition source 6 consisting of an electron gun and a crucible 5 is provided at the inner bottom of the vapor deposition tank 2 . Crucible 5
The evaporated substances fly upward and form an optical thin film on the surface of the glass substrate mounted on the substrate holder 7. The substrate holder 7 is supported by a holder support frame 8 in an inclined position, and by rotating this support frame 8 around a vertical axis along an annular rail 9, the substrate holder 7 can revolve while rotating. It is. The holder support frame 8 has a hollow drive shaft 10 that penetrates the ceiling wall of the vapor deposition tank 2 from inside to outside.
It is rotationally driven via the arm 11 and the passive bin 12. Further, the drive shaft 10 is driven via a gear train 14 using a motor 13 as a drive source.

A film thickness monitor 3 is provided to measure the film thickness of the optical thin film in real time. This film thickness monitor 3 uses a monitor glass 15 installed in a flying region of evaporated substances as a sample.
This is a film thickness monitor using a reflected light method that determines the film thickness by measuring the degree of reflection of the detection light irradiated onto the film. It is composed of a mirror box 17 for changing and guiding measurement light (measurement light), a light receiver 18, and a power supply unit for a measuring instrument body and a projector (not shown). The light emitter 16 and the light receiver 18 are arranged to face each other with a mirror box 17 in between.

In FIG. 1, the projector 16 has a light source 2 inside the case 19.
0, a pinhole plate 21, a chopper (not shown), and a condensing lens 22 are arranged in the order shown. The monitor glass 15 is irradiated with the focused detection light.

Inside the mirror box 17, a first reflecting mirror 24 that reflects the detection light toward the monitor glass 15 and a second reflecting mirror 24 that reflects the reflected light from the monitor glass 15 toward the photoelectric conversion unit 30 of the light receiver 18 are provided. Mirrors 25 are arranged adjacent to each other. The mirror box 17 is connected to the drive shaft 1 described above.
The monitor glass 15 is attached to the upper end of a bearing unit 26 that supports 0, and holds the monitor glass 15 via a cylindrical holder 27 provided at the bottom thereof. As shown in FIG. 2, the holder 27 passes vertically through the drive shaft 10 and is inserted into the vapor deposition tank 2.

The light receiver 18 includes an optical path tube 29 mounted on the mirror box 17 facing the second reflecting mirror 25, and this optical path tube 29.
The photoelectric conversion unit 3 is separably bonded and fixed to the photoelectric conversion unit 3.
0, and an optical path tube 29 on the optical path side of the unit 30
It is composed of a filter 31 and the like arranged inside. The filter 31 is attached to a filter holding frame 32 attached to the optical path tube 29.
It is removably mounted on the monitor glass 15, and its optical interference allows only monochromatic light of a specific wavelength to pass through from among the light reflected from the monitor glass 15. The charging conversion unit 30 is
It contains a photoelectric conversion element such as a phototube or photodiode, a head amplifier, etc., and outputs a signal current after photoelectrically converting the monochromatic light to the main body of the measuring instrument.

In order to confirm the position and direction of the reflected light on the light receiving surface of the charging conversion element, or to adjust the deviation thereof, the charging conversion unit 30 is guided and supported so as to be horizontally movable by a guide means 33, and the photoelectric conversion unit 30 is A second reticle 35 and a second reticle 35 are installed at two locations, one on the upper side of the optical path and one on the lower side of the optical path.
are placed.

As shown in FIGS. 1 and 3, the guide means 33 includes a pair of guide shafts 36 that are perpendicular to the center narrowness of the optical path tube 29;
It consists of a slider 37 attached to the bottom wall of the photoelectric conversion unit 30 and slidably supported by both guide shafts 36, and the photoelectric conversion unit 30 is placed in the use position where it is joined to the optical path tube 29 (as shown in FIG. 3). (imaginary line position) and optical tube 29
It is guided and supported so that it can freely slide between a standby position where it is separated from the optical path and is retracted out of the optical path as shown by the solid line in FIG. The guide shaft 36 is provided with a stopper 38 that positions the photoelectric conversion unit 30 at the use position. The position of the photoelectric conversion unit 30 can be changed using the guide shaft 36.
Air cylinder 4 provided on one frame 39 supporting
Do it with 0.

1st. Both second reticles 34 and 35 are made of transparent plates such as glass or plastic, and have index lines 41 formed on their surfaces to indicate the regular optical axis center position. The first reticle 34 is dropped into the filter holding frame 32 and attached thereto. For this purpose, the transparent plate is formed in the same shape as the filter 31. Further, the second reticle 35 is attached to a holding frame 42 on the downstream side of the optical path of the photoelectric conversion unit 30. This holding frame 42 is fixedly supported by the frame 39 via a bracket (not shown).

Next, optical axis adjustment will be explained.

When adjusting the optical axis, the photoelectric conversion unit 30 and the optical path tube 2
9 is released, the air cylinder 40 is operated, and the photoelectric conversion unit 30 is moved to the standby position. Then, the filter 31 is removed from the filter holding frame 32, and the first reticle 34 is attached to the frame 32. Further, the monitor glass 15 with a film formed thereon or a reflective mirror for adjustment is loaded in the holder 27.

In this state, the light source 20 is made to emit light, and detection light is irradiated in the same manner as when measuring the film thickness. The detection light is deflected by the first reflection mirror 24 and irradiated onto the monitor glass 15, and a portion of the detection light is reflected and reaches the second reflection mirror 25.

The second reflection mirror 25 diverts the reflected light toward the photoelectric conversion unit 30 .

The reflected light is transmitted to the first reticle 34 as shown in FIG.
and reaches the second reticle 35.

At this time, both reticles 34 and 35 are provided with an index line 42 indicating the regular optical axis center position.

Therefore, the suitability of the position and direction of the optical axis center of the reflected light can be determined based on the degree of deviation between the outline of the light and the index line 42 when the light passes through each reticle 34, 35.

Specifically, the first reticle 34 corrects the positional deviation, and the second reticle
The reticle 35 can determine the direction deviation,
For both reticles 34 and 35, if there is an outline of reflected light within the central circular indicator 42a, it means that the optical axis center is correct. Note that directional deviation refers to a state in which the position of the light passing through the first reticle 34 is correct, but the position of the light on the second reticle 35 is incorrect, as shown by the imaginary line in FIG. .

If a shift in position and direction is observed as above,
1st. By adjusting the posture of the second reflecting mirrors 24 and 25, the center of the optical axis of the reflected light can be optimized. In some cases, the attitude of the monitor glass 15 may be adjusted. After adjusting the optical axis, the first reticle 34 and filter 3
1, the photoelectric conversion unit 30 is returned to the use position and fixed to the optical path tube 29.

(Another Embodiment) In the above embodiment, the photoelectric conversion unit 30 is supported by the guide means 33 so as to be linearly movable, but the guide means 33 supports the unit 30 so as to be movable by swinging or rotating. Good too. Moreover, the air cylinder 40 can also be omitted.

The first reticle 34 only needs to be located near the light-receiving surface of the photoelectric conversion element, and is supported so that both reticles 34 and 35 are set on the optical path in conjunction with switching the position of the photoelectric conversion unit 30. It may be.

In the above embodiment, a reflection type film thickness monitor has been described, but since the present invention can also be applied to a transmission type film thickness monitor, the measurement method of the film thickness monitor is not limited.

In addition, 1st. If each of the second reticles 34, 35 is provided with a plurality of photoelectric conversion elements so that the position of the outline of the light can be electrically specified, the reflection mirror It is also possible to display the details of posture adjustment in 24 and 25, or to perform automatic posture adjustment.

(Effects of the Invention) As explained above, in this invention, the photoelectric conversion unit is separable from the optical path tube, and is further supported movably between the use position and the standby position by the guide means, so that the center of the optical axis can be confirmed and The handling of the photoelectric conversion unit has been made easier during adjustment. In addition, a first reticle and a second reticle are provided on the optical path toward the photoelectric conversion unit, and the first reticle can be used to check the positional deviation of the central axis of the measurement light, and the second reticle can be used to check the deviation in the direction of the central axis of the measurement light. I did it like that.

Therefore, according to the film thickness monitor of the present invention, the optical axis adjustment work can be performed easily and with high precision by, for example, adjusting the attitude of the reflecting mirror while visually checking both the first and second reticles. This resulted in a significant reduction in the effort and time required for the work. In addition, since the center of the optical axis can be set with high precision, it is possible to improve the film thickness accuracy and the quality of the thin film, especially when forming optical thin films, and the overall productivity of the vacuum evaporation equipment can be improved. .

[Brief explanation of drawings]

1 to 4 show an embodiment of the film thickness monitor according to the present invention, FIG. 1 is a principle explanatory diagram showing the schematic structure of the film thickness monitor, FIG. 2 is a sectional view of the vacuum evaporation apparatus, and FIG. The figure is a plan view of the guide means and the photoelectric conversion unit, and FIG. 4 is a perspective view of only the reticle. DESCRIPTION OF SYMBOLS 1... Vacuum deposition apparatus, 2... Vapor deposition tank, 3... Film thickness monitor, 15... Monitor glass, 16... Floodlight,
17... Mirror box, 18... Light receiver, 29.
... Optical path tube, 30... Photoelectric conversion unit, 34...
Second reticle, 35... Second reticle, 41... Index line. 2 others Figure 2]

Claims (3)

[Claims] (1) Optical film thickness that includes a projector, a mirror box for changing the optical path, and a light receiver, and the receiver includes a photoelectric conversion unit and an optical path tube that guides measurement light toward this unit. In the monitor, the photoelectric conversion unit is separably joined to the optical path tube, and the photoelectric conversion unit is displaced between a use position where it is joined to the optical path tube and a standby position where it is separated from the optical path tube and retreated outside the optical path. the photoelectric conversion unit is guided and supported by a guide means, and a first reticle for confirming the optical axis position is placed near the light receiving surface of the photoelectric conversion unit and on the optical path side of the light receiving surface; An optical film thickness monitor characterized in that a second reticle for checking the optical axis direction is arranged on the lower side. (2) The optical path tube is provided with a filter that allows only measurement light of a specific wavelength to pass through, and a filter holding frame that fixes and holds this filter, and the structures of the mounting portions of the first reticle and the filter are configured to be the same. The optical film thickness monitor according to claim 1, wherein both members are configured to be replaceable with respect to the filter holding frame. (3) The optical film thickness monitor according to claim (1) or (2), wherein the second reticle is fixedly installed on the downstream side of the optical path from the photoelectric conversion unit in the use position.