SU1147769A1 - Device for checking film th ickness - Google Patents

Abstract

A device for controlling the thickness of films in the course of their application, containing a source of radiation, a modulator, a system of mirrors, one of which has a translucent cover, and a carousel with substrate holders, distinguished by the fact that, with the purpose of increasing the accuracy of control, the oyo is equipped with an obturator mirror coating, placed around the carousel and the mirror with a translucent coating with the possibility of synchronous rotation with the carousel, and the carousel has at least one through hole placed in place of one of the substrates residents.

Description

The invention relates to technology and the production of thin films, and can be used in the optical, radio and electronic industries. A device for controlling the thickness of the films during their deposition is known, which contains an auxiliary substrate (witness) coated with a transparent film, and the thickness of the film is controlled by comparing the radiation intensity through the deposited film with the control intensity of the radiation ij. A disadvantage of the known device is the high measurement error of the film thickness due to different conditions of film growth on the main and auxiliary substrates. . (The closest to the present invention is a device for controlling the thickness of films — containing a radiation source, a modulator, a system of mirrors, one of which has a translucent coating, and a rotating carousel with substrate holders 2J. However, the known device has a low accuracy of control of film thickness, caused by the instability of the reference signal due to the heating of the substrate. The centre / 1b of the invention is to increase the control accuracy during the film deposition process. An envelope containing a radiation source, a modulator, a system of mirrors, one of which has a translucent coating, and a carousel with substrate holders, is equipped with a shutter with a mirror coating, J is embedded between the carousel and the mirror with a translucent coating with the possibility of synchronous interoperability with the carousel, and the carousel has at least one through hole placed in place of one of the substrate holders.Figure 1 is a schematic representation of a device for controlling TOL1CINA films; in fig. 2, 3 and 4 - the mutual position of the carousel and the shutter. A device for controlling the thickness of films during deposition in a vacuum, mind (Fig. 1) contains a source of electromagnetic radiation 1, mode; a mirror 69J mirrors 3, 4, 5 and 6 and a mirror 7 with a translucent coating, rotating carousel 8 with a substrate holder 9 and a through hole 10, sources of evaporated material 11. The device has an obturator 12 rotating synchronously with a carousel 8, made in the form of a disk with protrusions 13 and slots. From the side of the translucent mirror, the obturator is provided with a mirror coating. The number of substrates and holes of the carousel is equal to the number of projections of the obturator,. A thickness control device is housed in a vacuum chamber 14 having viewing windows 15, 16 and 17. A photodetector 18 is placed opposite the viewing window 16. FIG. 2, 3 and 4, the interaction of a carousel 8 and a shutter 12 rotating at the same angular velocity when measuring the intensity of radiation in the Transmittance and Reflecting modes during the spraying process is presented in phases. The device works as follows. When the modulator 2 rotates at a certain frequency, an order of magnitude higher than the rotational speed of the carousel 8 and the obturator 12, a signal is alternately sent to measure the radiation intensity in the Transmit mode: source 1 - mirror 3 - mirror 4 - substrate holder 9 with a substrate (or with a through hole 10) - mirror 7 s. With a translucent coating - photodetector 18, and in the Reflection mode: source 1 - mirror .6 - mirror 5 - mirror 7 podlrzhkoderzhatel 9 with the substrate (or mirror coating of the shutter 12) - mirror 7 - photodetector 18. FIG. . Figure 2 shows the position of the carousel and obturator, in which the signal of source 1, passed through a system of mirrors 3 and 4, then passes through a substrate with a sprayed film of substrate holder 9, reflects from mirror 7, and passes through viewing window 16 to a photodetector 18 to measure the radiation intensity in, pass mode. Since the frequency of rotation of the modulator is 10 times greater than the frequency of rotation of the carousel and the obturator, almost simultaneously with the measurement of the transmission, the radiation intensity is measured in the Reflect mode when the source signal.

Having passed the system of mirrors 6-7 and reflected from the film deposited on the substrate, it is reflected from the mirror 7 and fed to the photodetector 18.

FIG. 3 shows the mutual position of the carousel and the obturator, in which the signal in the transmission mode (upper signal) does not pass, i.e. the transmittance is zero. The signal measuring the reflection (bottom signal), passed through the system of mirrors, is reflected from the mirror surface of the projections 13 of the obturator 12 and goes to the photodetector 18 to measure 1 (30% reflection required as a reference signal to measure the real reflection of the film. Zero The drop in this case is used to correct the measuring device.

FIG. 2, 3 and 4 shows the relative position of the carousel and the shutter, when between the protrusions 13 of the shutter 12 there is a through hole 10 of the carousel 8. The upper signal npo goes to the mirror system and, reflected from the mirror 7, is fed to the photodetector 18, In this case the transmittance is 100 % (reference signal for measuring actual film transmission). The lower signal, having passed the system of mirrors, also passes through the opening 10 of the carousel 8, i.e. the reflection is zero in this case.

Thus, in the considered three phases of the carousel and the shutter operation, it is possible to obtain data on the real reflection and transmission of the sprayed film, 100% transmission and reflection as a reference signal, and 0% reflection and transmission for correction of the measuring device. A carousel with a different number of substrates and orifices can be used in practice, and the obturator with more or fewer protrusions, and does not match the number of substrates and apertures in the carousel, but in any case, the angular rotational speed of the obturator and carousel must comply with the equation

by

“0

Uk -; g-

op

where OD and i) are the angular rotational speed of the obturator and the carousel, respectively,

number of substrates and holes in the carousel;

V number of reflective surfaces of the obturator. The proposed control device allows high-efficiency measurements to be performed on the reflection and transmission of sprayed films in the process of obtaining interference coatings with the required characteristics.

Claims (1)

CONTROL DEVICE THICKNESS OF FILMS during their application, containing a radiation source / modulator, a system of mirrors, one of which has a translucent coating, and a carousel with substrate holders, characterized in that, in order to increase the accuracy of control, it is equipped with a mirror-coated shutter, placed between the carousel and the mirror with a translucent coating with the possibility of synchronous rotation with the carousel, and the carousel has at least one through hole located in place of one of the substrate holders. 1147769 1