JPS6130029B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum evaporation apparatus suitable for producing photoconductive films and other vacuum-deposited films in which component ratio gradients in the film thickness direction are particularly problematic.

Conventionally, when a photoelectric film is formed from multiple types of elements by vacuum evaporation, the film is formed into a multilayer structure with a large number of layers having different component ratios. However, in such a lamination method, unless the thickness of each layer is made sufficiently small, there is a risk that light interference will occur between each layer. In addition, it is difficult to regulate the component ratio gradient in the film thickness direction, causing variations in the movement of charged carriers, making it difficult to obtain a good photoconductive film.

According to the vacuum evaporation apparatus of the present invention, the first airless is provided between the evaporation source of the first element and the evaporation processing position, and the evaporation source of the second element different from the above element is connected to the evaporation processing position. The vapor deposition process is performed from both evaporation sources by selectively controlling the opening degree of each of the first and second eyeres based on the signal from the film thickness monitor. The control of the amount of steam flow towards a location will be described in detail below in conjunction with the embodiments shown in the drawings.

In FIG. 1, a turntable 2 that rotates at a constant speed together with a rotating shaft 1 has 16 circular through holes 3a, 3b,
3c...3p, and a through hole 3a for detecting the thickness of the deposited film
15 through holes 3b, 3c except for... 15 in 3p
Glass disks 4b, 4c... as individual deposition target substrates.
...4p are each attached by fitting. The glass disks 4b, 4c...4p serve as the face plates of the image pickup tube, and a transparent conductive film is already attached to the lower surface of the glass discs, and a photoconductive film is formed on the surface of the transparent conductive film. Vacuum deposited.

When the photoconductive film is made of selenium (Se) and arsenic (As), the first element, Se, is placed in the first crucible 5, and the second element, As, is placed in the second crucible 6. It can be paid. The first and second crucibles 5 and 6 are arranged at an angle so that their central axes 5a and 6a intersect at the center of the through hole 3a, and the first film thickness monitor is located on an extension of the central axis 5a. 7
A second film thickness monitor 8 is provided on an extension of the central axis 6a. That is, the first crucible 5 faces the first film thickness monitor 7 through the through hole 3a, and the second crucible 6 faces the second film thickness monitor 8 through the through hole 3a.

During the vapor deposition process, the turntable 2 rotates in the direction of the arrow shown in the figure, so that the position of the illustrated through hole 3a, that is, the single vapor deposition process position A, the other through holes 3b, 3c, . . . 3p and the glass disc. 4b, 4
c...4p will be sent in sequence, and this cyclic operation will be repeated.

The first and second crucibles 5 and 6 are heated by heaters 9 and 10, and the heating temperature is detected by thermocouples 11 and 12 provided at the bottom of each crucible 5 and 6. Further, cylindrical covers 13 and 14 are provided around both crucibles 5 and 6,
The covers 13, 14 and the partition plate 15 block radiant heat and prevent the vapor flow from dispersing in undesirable directions. Note that the covers 13 and 14 and the partition plate 15 are cooled with water or a cryogen such as liquid nitrogen, if necessary.

The film thickness monitors 7 and 8 are composed of crystal oscillator type film thickness gauges, and the first and second cylindrical covers 16 and 17 surrounding the monitors are connected to the corresponding crucibles 5 and 8 respectively.
It is for guiding only the vapor from the evaporation source 6 to the film thickness monitors 7 and 8, and the smaller the inner diameter and the longer the cylinder length, the less the vapor from other evaporation sources can be mixed in. However, on the other hand, the sensitivity of the film thickness monitor decreases, so it is necessary to select an appropriate inner diameter and cylinder length depending on the material to be evaporated.

The box-shaped first eyeless 18, which is freely inserted between the first crucible 5 and the vapor deposition processing position A, allows the extension line of the crucible central axis 5a to deeply penetrate into the top plate portion 18a. wedge-shaped opening 1
It has 9. In addition, the box-shaped second eyeless 20, which is freely inserted between the second crucible 6 and the vapor deposition processing position A, has an extension line of the crucible central axis 6a deeply inserted into its top plate portion 20a. It has a wedge-shaped opening 21 that can be opened. Therefore, when the first and second eyeres 18, 20 are moved in the direction of the arrow shown in the figure, the amount of vapor flow from both evaporation sources toward the vapor deposition processing position A can be controlled according to the amount of movement. . In addition, both eye rests 1
The rotation centers of 8 and 20 are the same as the rotation center of the turntable 2.

The structure shown in FIG. 1 is housed within a bell gear 22 as shown in FIG. 2, and is driven and controlled from outside the bell gear 22. The gear mechanism 23 is for driving the first and second eyerests 18 and 20, and the vacuum pump and vacuum valve 25 are for keeping the inside of the bell gear 22 in a vacuum. Further, the cylindrical covers 16 and 17 are attached to the partition plate 26, and the first and second crucibles 5 and 6 and the covers 13 and 14 are attached to the pedestal 27,
A steam introduction cylinder 29 is attached to the partition plate 28.

In order to form a thin film having a composition of, for example, 90 atomic % Se and 10 atomic % As using the vacuum evaporation apparatus configured as described above, the inside of the bell gear 22 is 1×
While keeping the degree of vacuum below 10 ^-6 Torr, turntable 2 is rotated at a speed of 30rpm, and heaters 9 and 10 are turned on.
A heating current is passed through. At this time, the first and second
The eyelets 18 and 20 of the crucibles 5 and 6 are both close to each other, and the degree of opening is zero. 2 Eyeless 18,2
The opening degree of 0 gradually increases.

As a result, Se and As are simultaneously vacuum-deposited onto each of the 15 glass discs fitted into the turntable 2.
Each time the turntable 2 makes one revolution, the first and second film thickness monitors 7 and 8 send out data signals whose magnitude is proportional to the actual amount of Se and As deposited. Both eyelets 18 and 20 may be moved to adjust their apertures so that the ratio of Se to As determined by the data signal is 9 to 1 in terms of atomic ratio. However, both eyelets 1
When the opening degree control of 8 and 20 is insufficient for sufficient adjustment, the magnitude of the current flowing through the heaters 9 and 10 may be controlled as a companion means.

Calculates data signals from film thickness monitors 7 and 8,
It is preferable to use a computer to feed back a signal based on the result of this calculation to the eyeless drive section or the heater current control section in a short time. However, the calculated value of the predetermined component ratio may be calculated in advance, and the eyeless drive section or the heater current control section may be manually operated to obtain the calculated value, and in this case, a computer is not required. In manual operation, for example, a pen recorder is used to draw a control curve indicating the expected amount of vapor deposition on the recording paper in advance. Then, the output signal of the film thickness sensor is given to the pen recorder, and the eyeless drive section or the heater current control section is operated so that the output pen instruction of the pen recorder matches the control curve.

When forming a thin film with a thickness of 4 μm containing Se as the main component and tellurium (Te) added in a specific distribution in the film thickness direction, the first and second crucibles 5,
6 is filled with Se and Te, respectively, and the inside of the bell gear 22 is maintained at a vacuum level of 1×10 ^-6 Torr or less. While rotating the turntable 2 at a speed of 30 rpm, the film thickness monitors 7 and 8 monitor the opening degrees of the first and second eyerests 18 and 20 and, if necessary, the current flowing through the heaters 9 and 10. The amount of Se and Te deposited is adjusted based on the signal from the Then, when the total thickness of the deposited film reaches 4 μm, the opening degree of both the eyeres 18 and 20 is made zero.

As described above, the vacuum evaporation apparatus of the present invention forms multi-element thin films with different vapor pressures by the multi-source rotary evaporation method. Since the mixture is controlled and mixed on the surface to be deposited, the component ratio gradient in the film thickness direction can be arbitrarily controlled and can be made to be a completely continuous gradient. Further, a large number of films can be formed with high precision and high efficiency under the same conditions, and a deposited film with fewer defects can be obtained compared to the conventional flushing vapor deposition method. Furthermore, since the deposition rate is stabilized, there are almost no electrical defects in the film and there is no problem of light interference, which is particularly useful for the production of photoconductive films for image pickup tubes or image sensors, photodetectors, interference filters, etc. It can be applied to obtain excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main parts of a vacuum evaporation apparatus embodying the present invention, and FIG. 2 is a side sectional view of the same apparatus. 2...Turntable, 3a...Through hole for detecting the thickness of the deposited film, 3b to 3p...Through hole for mounting the substrate to be vapor deposited,
5, 6... Crucible, 7, 8... Film thickness monitor, 1
8, 20...Airless, A...Vapor deposition processing position.

Claims (1)

[Claims] 1. A turntable that rotates at a constant speed and has a through hole for detecting the thickness of a deposited film and a large number of through holes for mounting a substrate to be deposited on a plate surface area along the circumference, and is set at a position where the through holes pass through. A first one disposed below the turntable so as to face a single deposition processing position.
and a second crucible, first and second film thickness monitors disposed above the turntable so as to face the first and second crucibles, respectively, between the first crucible and the vapor deposition processing position. a first eyeless that can be inserted freely between the second crucible and the vapor deposition processing position, the opening degree of which is controlled based on the output signal of the first film thickness monitor; A vacuum evaporation apparatus comprising a second eyeless whose opening degree is controlled based on the output signal of the second film thickness monitor.