JPS6020106A - Thin film forming device provided with optical interference type film thickness monitor - Google Patents

Abstract

PURPOSE:To realize a clear detection with a simple structure by placing a reflector and a light transmitting plate in a gap between plural substrates placed on a substrate holder, and using reflected light for detecting a synchronizing signal. CONSTITUTION:Monochromatic light for monitoring an optical interference, projected from a laser light source 1 is reflected by mirrors 41, 42- provided between plural substrates 51, 52- on a substrate holder 55 rotating around a shaft 10, and reaches a synchronizing signal detecting sensor 64. An optical path reaching a regular optical interference monitoring sensor 6 is path of measuring light reflected by the surface of the substrate 51, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a synchronizing signal generating device for an optical interference monitor for film thickness control in a transparent thin film forming apparatus.As shown in FIG. Light 2 of a predetermined wavelength is projected onto the surface of the substrate 5 to be measured from the light source 1, and the light 15 reflected from the top surface of the substrate 5 and the light 1 reflected from the top surface of the transparent thin film 4 are generated.
There is a method that takes advantage of the fact that interference occurs due to the optical path difference between the light beams 15 and 4, and the light intensity of the combined reflected light beam 3 of the light beams 15 and 14 causes periodic brightness and darkness as the thickness of the transparent thin film grows, as shown in FIG. It is well known.

However, this method does not cause any problems when the substrate 5 is stationary, but when the substrate is moving or rotating, similar interference light is generated from surrounding reflective surfaces other than the substrate 5. The problem is that depending on the conditions, the interference light may be confused with the interference light from the substrate 5, making it impossible to monitor correctly.

Therefore, a means for selectively detecting only the light reflected from the substrate 5 is required. For example, as in the case of the rotary substrate holder shown in FIG. Perforated plate 11° Reflected light emitted from light source 1 is received by optical sensor 6.

The method of cupping is adopted.

However, such a method of separately installing a synchronization detector causes quite troublesome problems such as the space required for its installation and the necessity of synchronization adjustment.

One way to solve this problem is to use the reflected light of a light beam for optical interference monitoring, which is projected toward the substrate holder, for direct dimension synchronization detection, as will be described later.

If the reflected light of the optical beam for optical interference monitoring is used, for example, in a rotating substrate holder 55, the space between the substrates 5, 52, etc. on it is used as shown in Fig. 4. “Nimi”
'41, 42, . . . , but if these mirrors are installed only in the area where the transparent thin film is attached and grown, the intensity of the reflected light will vary as described above.

Therefore, this cannot be used as verification light for synchronization. Therefore, it is necessary to install a mirror in the area where the transparent thin film does not adhere, guide the light beam to this mirror position, and receive the reflected light at a predetermined position, so it is necessary to consider the optical path design in advance. was there.

The first object of the present invention is to make it unnecessary to install a separate synchronization signal generator inside or outside the apparatus by directly utilizing the measurement light inside the vacuum chamber for synchronization detection.

A second object of the present invention is to provide a synchronization signal generation method that does not cause changes in the strength of reflected light for synchronization measurement.

A third object of the present invention is to provide a synchronization detection method that does not cause instability in the synchronization signal due to adhesion of Jl and iJ, and does not require frequent replacement of mirrors, etc. .

FIG. 4 shows an embodiment of the present invention. Figure 4 shows laser light source 1
The monochromatic light for the optical interference monitor is projected from the.

A plurality of substrates 51 , 52 . on a substrate holder 55 rotating around an axis 10 . ...mirror 41.4 provided between
2. The outline of the path of light that is reflected by ... and reaches the synchronization signal detection sensor 64 is shown by a solid line.

The optical path to the regular optical interference monitor sensor 6 is based on base 4ii.
51 This is the path of the measurement yt reflected on the surface of the target, and is indicated by the dotted line 3 in the figure.

Figure 5 is an enlarged view of mirror 41 in Figure 4.
i-side view.

and a schematic diagram of a light path. 90 is the wall of the vacuum chamber.

91 is a sealing material, and 7 is a peephole.

The light 2 projected from the laser beam (Jb', ) passes through the semi-transparent glass plate 17, passes through the peephole 7 of the vacuum chamber, and enters the vacuum chamber. After passing through the transparent cylinder Bp adhesion prevention glass plate 18 attached to the pillar 9 of 55, the surface 50 of the substrate 51 etc. (50 indicates the position occupied when the substrate 51 etc. arrives at the position of this viewing window 7) ), the light hits the reflector 40 mounted at a slight angle α and is reflected, passes through the optical path 19, enters the photo sensor 64, and becomes an electrical synchronization signal.According to the configuration of the present invention, 2. The transparent thin film adheres to the glass '4υ18 which is being prepared, and 9. it does not adhere to the reflective plate 40.

Therefore, in the reflected light, there is almost no change in the intensity of the interference light caused by the attachment of the transparent thin film. Further, in the transparent thin film adhesion prevention glass plate 18, the optical paths of the incident light 2 and the reflected light 19 reflected by the reflecting plate 40 are separated from each other, so that no interference occurs between the two.

If the refractive index of the transparent thin film adhesion prevention glass plate 18 and the transparent thin film are made to be the same or similar, as shown in optical theory, even if the transparent thin film adheres and grows, the transmitted light in this part will be extremely weak. This can easily happen.

Furthermore, with such a configuration, the synchronization signal detection device can be housed in an extremely small space. Transparent thin film adhesion prevention glass 18
There is no need to frequently replace the second reflecting plate 40, and it is possible to obtain synchronized detection light whose intensity is approximately constant over a long period of time.

FIG. 6 shows another embodiment of the invention. This example is a case of a substrate holder that moves linearly, and mirrors 41, 42, .・・・
・It is installed.

The synchronization signal detection structure of the thin film forming apparatus with an optical interference type monitor of the present invention is as described above, and although it has a simple structure, it enables extremely clear detection of synchronization signals. Furthermore, it does not require replacement or cleaning over a long period of time, making it highly practical.

In a device that creates a transparent thin film while rotating and moving,
Its industrial effects are remarkable.

Note that the present invention is not limited to the illustrated embodiment. For example, the optical path can be freely designed. Furthermore, it can be broadly applied to all types of movable substrate holders.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams showing the principle of the present invention and the strength and weakness states of interference light. FIG. 3 is a diagram showing a conventional example in which an interference monitor is attached to a thin film forming apparatus having nine evaporation sources and a cylindrical substrate holder. FIG. 4 shows an embodiment of the synchronous signal generator according to the present invention,
FIG. 5 shows a detailed sectional view thereof. Figure 6 shows the second embodiment of the present invention.
An example is shown below. In fig. DESCRIPTION OF SYMBOLS 1...Laser light source 4...The transparent thin film 5...Substrate 18...Adhesion prevention glass plate 18'...Reflector plate. Patent applicant: Nichiden Anelva Co., Ltd. FIG, 6 〈-4142

Claims (1)

[Claims] In the gap between the plurality of substrates arranged on the substrate holder of the film forming device, there is a reflecting plate having an angle of inclination different from the substrate surface, and the transparent thin film is attached to the reflecting plate in front of the reflecting plate. A light transmitting plate was placed to prevent the growth, and the light emitted from the light source was transmitted through the light transmitting plate and reflected by the reflecting plate. The reflected light was used to detect the synchronization signal of the optical interference monitor. A thin film forming device with an optical interference type film thickness monitor.