Vacuum evaporator

A vacuum evaporator is characterized in that hot-cathode filaments (7) are provided as the electron source around a tip of a rod evaporation material (4); the peripheries of the rod evaporation material (4) and the hot-cathode filaments (7) are disposed in parallel to a conductive cooling member (1) of a good heat conductive metal which is partly contacted with the atmosphere to decrease the dissipation of radiation heat produced from the hot-cathode filaments (7) and a tip (41) of the rod evaporation material (4) into a vacuum vessel a; heat absorbed by the conductive cooling member (1) is quickly conducted through the conductive cooling member and discharged to the atmosphere to prevent the temperature of the electron impact heating part from increasing and to prevent the increase of the gas discharge due to the heat dissipation from the electron impact heating part.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an evaporation source (Knudsen cell or 
e-gun) of a vacuum evaporator for so-called dry plating by which a solid 
material is melted or sublimated in a vacuum device by electron impact 
heating so as to be evaporated as atomic or molecular beams and adhered 
onto a solid deposition substrate, or to a molecular beam source of a 
molecular beam crystal growth device (MBE) by which evaporated molecular 
beams are gradually deposited on a crystal substrate to form a crystalline 
film. 
2. Description of the Related Art 
Vacuum deposition of a solid material is a very significant technology from 
an industrial point of view and inevitable to form a film. Known 
evaporation methods include a resistance heating method and an electron 
impact heating method. The resistance heating method is a type which 
directly contacts an evaporation source material with an evaporation 
material (film material), and the evaporation source material has a 
temperature higher than the thin film material, so that there are 
disadvantages such as mixing of impurities into the film material, a 
reaction with the evaporation source material and a limitation owing to a 
melting point of the evaporation source material. The electron impact 
heating method was developed to avoid such disadvantages and directly hits 
the electrons against a portion of the evaporation material for heating. 
Such highly purified film forming technologies are increasing in importance 
as the electronics-related technologies undergo further development, and 
an electron beam heating method which does need to take an evaporation 
source container material into account stands without a rival at forming a 
film by depositing a high-melting point material. Its most prominent 
advantage is that since the solid evaporation material can be partly 
heated to be melted and evaporated by squeezing the electron beam into a 
thin line, a crucible for the melted material is not needed, and a 
material for the crucible does not melt into a melted evaporation liquid. 
As the electron source in this case, known methods include one which uses 
an electron gun A, namely an electron gun (e-gun) which accelerates 
electron beams of 10 to 110 mA taken out of a hot-cathode filament with a 
high-voltage electric source of 10 to 10 KV to linearly hit a sample C 
from a distance as shown in FIG. 7, and one which deflects electron beams 
(electron beams E) by a magnetic field as shown in FIG. 8. In FIG. 7 and 
FIG. 8, B denotes an accelerating electrode, D a cooling water, and d a 
substrate. And, the latter method is mainly used today. 
But, the electron beam heating method using the electron gun has 
disadvantages as given below. 
(1) It is necessary to precisely control the electron beams, the electrode 
has a complex structure and a large size, and the device is expensive. 
(2) A melted material holding member on the side where the electron beams 
do not reach is required to be kept water-cooled, requiring a 
water-cooling line. And, this structure may often become the cause of a 
trouble. 
As an electron beam heating method which does not have the above-described 
disadvantages (1) and (2), there is a known method by that a rod 
evaporation material 4 has its leading end directly exposed to electrons 
coming out of a hot-cathode filament 7 which is provided in the 
neighborhood of the material to melt and evaporate the leading end only as 
shown in FIG. 9. This method does not need a crucible either, and a 
high-melting point material can be subjected to high purity deposition. 
And, the device is very simple and inexpensive. In the drawing, M denotes 
molecular beams, f a high-voltage power source, and h a filament heating 
power source. 
But, this method also has disadvantages as follows. 
(3) The evaporation substance scatters into the whole space to contaminate 
a vacuum vessel. 
(4) The temperature of the vacuum vessel is raised by radiation heat which 
is generated from the hot-cathode filament and the melted part, and its 
vacuum is degraded. 
(5) As means for remedying the above disadvantages (3) and (4), another 
evaporation source may be configured by covering the hot-cathode filament 
7 and the end of the stick evaporation material 4 shown in FIG. 9 by 
another screening electrode. 
However, the screening electrode is heated to a high temperature in a range 
of 600.degree. to 800.degree. C. by radiation heat from the evaporating 
end and the hot-cathode filament, and the gas discharge from the electrode 
is increased. Besides, radiation from the high-temperature screening 
electrode increases the temperature of the vacuum vessel wall, and the gas 
discharge is also increased. 
(6) In any electron beam heating methods described above, a serious 
disadvantage over the above disadvantages (1) through (5) is that the 
electron beams ionize the atoms and molecules being evaporated to produce 
a large amount of ions. And, a portion of primary electrons from the 
filament does not serve for heating but is reflected and dissipated on the 
material surface to produce backscattered electrons which are added 
together with secondary electrons to the above ions. These ion and 
electron groups hit the film formed on the deposition substrate, greatly 
affecting on the structure and physical properties of the film. 
(7) Besides, when the vacuum wall is hit by these backscattered electron 
groups, gas discharge from the wall is tremendous. 
(8) In the method shown in FIG. 9, it is known to cover with the screening 
electrode to prevent the electrons from diffusing. In such a case, the 
screening electrode's electric potential may be determined to be an earth 
(zero) potential, namely at the same electric potential as the vacuum 
vessel, or an electric potential lower than the vacuum vessel. When it is 
a zero potential, positive ions produced by the electron bombardment hit 
the deposited film at the earth potential at a high speed, so that the 
film quality is enormously deteriorated. And, when the evaporation 
material is at the earth potential and the screening electrode and the 
filament are at the minus electric potential, not only the backscattered 
electrons but also the primary electrons from the filament hit the vacuum 
wall, and gas discharge from the wall is tremendous. A metallizing 
apparatus having the same electrode structure as the one shown in FIG. 9 
was produced, and an electron current entering its vacuum wall was 
measured. It was found that backscattered electron groups corresponding to 
20 to 30% of the primary electrons were entering the vacuum wall. At the 
time, it was also found that a degree of vacuum was degraded by two to 
three digits as compared with that before the electron bombardment and 
carbon monoxide gas which is most deleterious to the film formation was 
discharged in a large amount. 
(9) An issue remained to be solved through the vacuum deposition technology 
in general for the resistance heating method in addition to the electron 
bombardment problem is that no appropriate method is available to directly 
measure a vapor pressure (molecular beam intensity) of evaporated atoms or 
molecules. The only one method now available measures the thickness of a 
film deposited to determine a film growth rate with an apparatus called a 
film pressure monitor which is provided in the neighborhood of the 
deposition substrate. This method cannot monitor accurately the molecular 
beam intensity in the neighborhood of the center of the molecular beams 
while depositing. 
(10) Besides, in the case of the conventional device, radiation heat from 
the evaporation source is dissipated within the vacuum device to raise the 
temperature of the device. To prevent a degree of vacuum from being 
degraded by the gas discharge and the film formation from being affected 
adversely, the inner wall of the vacuum device is made to have a double 
structure, and a liquid nitrogen cooling shroud for circulating liquid 
nitrogen between the double layer of the inner wall is essential. 
Therefore, the device (particularly, MBE: molecular beam crystal growth 
device) becomes very expensive, its running cost is very high, and its 
operation is not easy. But, even if liquid nitrogen is used for cooling, a 
degree of vacuum retained while depositing was about 10.sup.-6 to 
10.sup.-7 Pa. 
(11) As to recent film forming technologies, attention is being given to a 
compound semiconductor film and an alloy magnetic film which occurs a 
chemical reaction and alloy on the deposition substrate by evaporating a 
plurality of different materials at the same time. But, the conventional 
methods shown in FIG. 7 to FIG. 9 need to dispose a plurality (the number 
of filaments) of evaporation sources within the same vacuum device, the 
device becomes large, and the disadvantages (1) to (10) described above 
are increased by the multiples of the number of devices used. 
SUMMARY OF THE INVENTION 
The invention has been completed in view of the above-described 
disadvantages of conventional technologies and aims to provide a vacuum 
evaporator which does not scatter electrons or ions and has a simple 
electrode structure, does not need water cooling or liquid nitrogen 
cooling, and has an evaporation source which does not scatter molecular 
beams from the deposition source or radiation heat to any parts other than 
a deposition substrate and can be produced inexpensively without degrading 
vacuum. Furthermore, it is aimed to provide a vacuum evaporator by which 
the molecular beam intensity while depositing can be monitored at the same 
time, and a plurality of materials are evaporated from a single 
evaporation source at the same time to easily form a compound 
semiconductor or an alloy film. 
The invention described in claim 1 relates to a vacuum evaporator that a 
solid substance provided within a vacuum vessel is melted and evaporated 
or sublimed by electron impact heating to form atomic or molecular beams 
and to adhere onto a separately provided deposition substrate, 
characterized in that: 
hot-cathode filaments are provided as an electron source around a tip of a 
rod evaporation material; a conductive cooling member of a good heat 
conductive metal which is partly contacted with the atmosphere is provided 
on the periphery of the rod evaporation material and the hot-cathode 
filaments in parallel to the rod evaporation material to decrease the 
dissipation of radiation heat produced from the hot-cathode filaments and 
the tip of the rod evaporation material into a vacuum vessel; and heat 
absorbed by the conductive cooling member is quickly conducted through the 
conductive cooling member and discharged to the atmosphere to prevent the 
temperature of an electron impact heating part from increasing and to 
prevent the increase of the gas discharge due to the heat dissipation from 
the electron impact heating part. 
The invention described in claim 2 relates to a vacuum evaporator according 
to claim 1, wherein a screening electrode is provided between the electron 
impact heating part and the conductive cooling member to prevent the 
dissipation of electrons and ions generated from the evaporation tip of 
the rod evaporation material and the hot-cathode filaments. 
The invention described in claim 3 relates to a vacuum evaporator according 
to claim 2, wherein the screening electrode is made to be an electrical 
potential lower than the hot-cathode filaments' potential, and an ion 
current flowing to the screening electrode is detected to monitor and 
detect evaporation intensities of evaporated atomic beams and molecular 
beams. 
The invention described in claim 4 relates to a vacuum evaporator according 
to claim 2, wherein an atomic and molecular beam discharge port formed on 
the screening electrode has a meshed structure. 
The invention described in claim 5 relates to a vacuum evaporator according 
to any one of claims 1 to 4, wherein the rod evaporation material is 
formed by bundling a plurality of different materials into one body. 
In the above-configured vacuum evaporator, high-temperature radiation heat 
and conduction heat from the hot-cathode filament and the tip of the 
evaporation material do not enter an analyzer provided on the vacuum 
vessel wall or within the vacuum vessel but are quickly discharged outside 
through the conductive cooling member, and vacuum degradation due to the 
dissipation of various electrons and ions containing the backscattered 
electrons can be prevented, the deposited film can be prevented from being 
damaged, and water cooling or liquid nitrogen cooling is not required. 
In addition, the intensity of the molecular beams at the time of depositing 
the evaporated atomic beams can be monitored, a plurality of different rod 
evaporation materials are integrally bundled to form the rod evaporation 
member, so that there is provided a vacuum evaporator having quartet 
effects which is a single evaporation device but can easily form a 
compound semiconductor or alloy on a deposition substrate. 
Preferably, the screening electrode has a structure divided into two in the 
coaxial direction with the rod evaporation material, so that the ion 
current is monitored by the screening electrode having a meshed opening in 
the neighborhood of the tip of the rod evaporation material. The screening 
electrode is preferably configured to make degassing from the hot-cathode 
filament by electron impact. It is preferred to have a structure on the 
opposite side of the evaporation tip of the rod evaporation material so 
that the rod material which is consumed with evaporation can be fed.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The invention will be described with reference to examples shown in the 
drawings. Components identical to those shown in FIG. 7 to FIG. 9 are 
given the same reference numerals. 
FIG. 1 shows a conduction cooling rod material electron impact heating 
evaporation device practicing the invention. In the drawing, 1 is a thick 
wall cylindrical conductive cooling member made of oxygen free copper, 
which is configured of a good heat conductor formed of copper or copper 
alloy or aluminum or aluminum alloy. A copper donut-like disk 2 which 
prevents ions produced by electron impact and radiation heat which does 
not serve for heating a material from being diffused to a vacuum vessel 
wall is fixed by bolts to one end of the conductive cooling member 1 which 
is disposed on the vacuum side. And, an electrode holder 3 made of oxygen 
free copper is fixed to the interior while retaining the above functions. 
Insulation terminal groups 31, 31' for fixing an electrode which 
configures an electron impact heating unit is fixed to the oxygen free 
copper electrode holder 3. 
A portion 11 which is on the atmosphere side of the conductive cooling 
member 1 has a plurality of vacuum insulation terminals 12, 12' welded by 
electron beams, and also cooling fins 13 and a stainless steel vacuum 
flange 14 welded. And, a small stainless steel vacuum flange 15 is welded 
to the other end of the conductive cooling member 1, and a rod evaporation 
material 4 and an introduction member 5 for delivery are connected 
thereto. 
At the center of the electrode holder 3, a hole 32 is formed to pass the 
rod evaporation material 4 therethrough, and the rod evaporation material 
4 is slid through the hole 32 into an electron impact heating chamber 6. 
Within the electron impact heating chamber 6, a circular hot-cathode 
filament 7 made of a tungsten material is mounted on the two insulation 
terminals 31 in a substantially horizontal position with respect to a tip 
41 of the rod evaporation material 4. And, the insulation terminals 31, 
31' are electrically connected to the vacuum insulation terminals 12, 12'. 
The filaments 7 and the tip 4 of the rod evaporation material 4 are 
surrounded by a tantalum metal cup-shaped screening electrode 8 which is 
mounted on another insulation terminal on the electrode holder 3 and two 
screening electrodes of a donut-shaped screening electrode 9. And, a hole 
91 is formed at the center of the donut-shaped screening electrode 9 to 
inject evaporated molecular beams, and this hole has a fine screen 92 made 
of a very thin tungsten wire. The two screening electrodes 8, 9 are 
electrically independent each other and connected to the vacuum insulation 
terminal groups of the vacuum insulation terminal 12'. 
The principle of operation of the invention will be described with 
reference to the above embodiment, and its effects will be described with 
reference to experiment data. 
FIG. 2 shows a state that the evaporation device of the invention is 
mounted on a vacuum vessel. The conductive cooling member 1 is mounted on 
the upper part of a vacuum vessel a. The vacuum vessel a is made vacuous 
by a vacuum pump c (not shown). In the drawing, b is a vacuum gage, d is a 
substrate, and M is a molecular beam. 
The screening electrodes 8, 9 are wired through the vacuum terminals 12, 
12' as shown in FIG. 3, and electron impact is performed to the two 
screening electrodes 8, 9 from the hot-cathode filaments 7 to make 
degassing. 
When the electron impact of about 1 KV.times.60 mA is performed, the two 
screening electrodes 8, 9 have a temperature exceeding 1000.degree. C. By 
this step, the gas discharge from the electrodes is lowered to a 
negligible level even when the temperatures of the screening electrodes 8, 
9 are raised to 600.degree. to 800.degree. C. at the next electron impact 
heating deposition. 
The electrodes are wired with a positive electrode at an earth potential 
(the rod evaporation material 4) as shown in FIG. 4, a reverse bias 
voltage of -2 KV is applied to the hot-cathode filaments 7, and the 
screening electrodes 8, 9 are set to a level 20 to 30 V lower than the 
hot-cathode filaments' potential. In this state, the hot-cathode filaments 
7 are turned on to hit the rod evaporation material 4 with electron 
impacts of 40 to 50 mA. 
As a result, the tip 41 of the rod evaporation member 4 melts, and a liquid 
ball dangles from the tip of the solid rod material 4. For example, when 
silicon having a diameter of about 2 mm is used for the rod evaporation 
material 4, the liquid ball has a diameter of about 5 mm and a temperature 
exceeding 1700.degree. C. 
At the time, radiation heat from the hot-cathode filaments 7 and the tip 41 
is shielded by the two screening electrodes 8, 9. Therefore, the two 
screening electrodes 8, 9 have a high temperature of 600.degree. to 
700.degree. C., but since they are surrounded by the oxygen free copper 
conductive cooling member 1 having a very small emissivity (absorption 
rate of radiation heat) of 2%, 98% of heat is returned to the screening 
electrodes 8, 9, then to the filaments 7. Therefore, the heating electric 
power of the filaments 7 is lowered to 1/2 to 1/3 of prior art, and 
absorption of heat by the cooling member 1, the donut-shaped disk 2 and 
the electrode holder 3 is very small. In other words, there is provided an 
energy-saving electron impact heating structure. 
Heat absorbed at a rate of 2% by the donut-shaped disk 2 and the electrode 
holder 3 is quickly discharged to the atmosphere through the oxygen free 
copper which has a very high heat conductivity, so that the temperature 
increase of the electron impact heating evaporation chamber 6 is 
suppressed to minimum. In the aforementioned example of the silicon 
material, the temperature at the head (the donut-shaped disk 2) of the 
conductive cooling member 1 was about 80.degree. C. 
Detrimental electron groups of backscattered electrons produced from the 
periphery of the electron impact heating evaporation source and secondary 
electrons are completely rebounded by the screening electrodes 8, 9, which 
are made negative with respect to the filament, to the rod material 
(positive electrode) to serve for heating. The screen 92 made of a very 
thin line formed on the hole 91 of the donut-shaped screening electrode 9 
through which the evaporated molecules pass serves to completely prevent 
the backscattered electrons and secondary electrons from scattering toward 
the deposition substrate. 
In the embodiment shown in FIG. 1, a disk electrode (not shown) was 
provided at the center hole of the donut-shaped cooling disk 2 with the 
screen 92 removed, and backscattered electrons and secondary electrons 
were measured. It was found that an electron current of 2 to 5 mA with an 
energy width of 0 to 300 eV came flying, and when a 30-mesh screen of a 
fine line having a permeability of 95% was used, an ammeter indicated 
zero. And, even when such screens were provided, it was found that a film 
formed on the deposition substrate and affected by the mesh of the screen 
was free from any spot, and a film with good quality could be formed. This 
effect results from the screen mesh which is smaller than the liquid ball 
at the tip of the evaporation material and disposed nearest to the 
evaporation source. 
With the electrode structure described above, at the tip 41 of the rod 
evaporation material 4 where evaporation occurs by heating, evaporated 
electrons are partly ionized by the flying electrons to positive ions and 
flown to the screening electrodes 8, 9. At this time, the ion current 
flowing to the screening electrodes 8, 9 is an ion current of evaporated 
atoms generated by the electrons discharged from the hot-cathode filaments 
7, and has the same function as a kind of hot-cathode ionization vacuum 
gage. In other words, when it is assumed that the steam pressure of 
evaporated atoms is P, the ion current is expressed as follow: 
EQU Ii=KPIe 
where, Ii is an ion current, Ie is an electron current, K is a proportional 
constant related to an ionization probability of evaporated atoms and an 
electrode structure. 
Therefore, the steam pressure of the evaporated atoms, namely an evaporated 
molecular beam intensity, can be seen by monitoring Ii. Especially, in the 
embodiment shown in FIG. 1, since the screening electrode is divided into 
two and the ion current on the evaporating side only can be monitored by 
the donut-shaped screening electrode 9, the intensity of molecular beams 
evaporating toward the substrate can be measured with high accuracy. In 
the examples shown in FIG. 1 and FIG. 2, by depositing on the substrate 
positioned about 100 mm away from the evaporation source, the results 
shown in Table 1 were obtained. And, vacuum during depositing could be 
retained at 10.sup.-6 to 10.sup.-7 without using liquid nitrogen. 
TABLE 1 
______________________________________ 
Evaporation 
Acceleration 
Electron Ion Deposition 
material voltage current current 
rate 
(2-mm dia. rod) 
E (KV) Ie (mA) Ii (.mu.A) 
.ANG./s 
______________________________________ 
Silicon 2 60 50 to 1 
Iron 1.5 30 80 to 2 
______________________________________ 
Description will be made of an ion impact problem that positive ions which 
are produced between the screen 92 of the screening electrode 9 and the 
tip 41 of the rod evaporation material 4 are partly accelerated by the 
screening electrode 9 to pass through the screen 82 toward the deposition 
substrate. This problem can also be solved by the present invention. 
Specifically, the positive ions moving through the screen 82 is 
accelerated from the electric potential intermediate between the screening 
electrode 9 and the tip 41 (an anode and an earth potential) of the rod 
deposition material 4, and many of the ions passed through the screen 92 
are pushed back by the donut-shaped cooling disk 2 at an earth potential 
toward the screening electrode. Even the ions which have passed through a 
portion having a loose gradient of potential in the center hole of the 
donut-shaped cooling disk 2 cannot reach the deposition substrate located 
at the earth potential. 
Description will be made of an embodiment of a rod evaporation member which 
is formed of a plurality of different materials bundled into one body. 
FIG. 5 shows a composite rod evaporation member, which is the rod 
evaporation material 4 formed by winding a pure iron wire 43 having a 
diameter of 0.7 mm into a spiral form around a silicon core rod 42 having 
a diameter of 2 mm. When a tip of the evaporation material is heated by 
the electron impact, silicon and iron react to become ferrosilicon (FeSi2) 
and evaporate to form a compound semiconductor film on the substrate. 
FIG. 6 shows an example of a composite rod evaporation member which is 
formed by covering a cobalt rod 44 as the core with an iron pipe 45. In 
this example, the two ferromagnetic metals are melted into a liquid ball 
41 before evaporating to form a magnetic alloy film on the substrate. 
Cobalt and iron have different melting point and steam pressure, but a 
mixing ratio of the liquid ball can be adjusted by appropriately selecting 
the thickness of the core wire and external pipe, so that a film having 
the corresponding alloy ratio can be formed. 
Besides, in this example, since the two ferromagnetic metals are melted 
into the liquid ball 41 before evaporating, it is preferable to provide a 
structure on the opposite side of the evaporation tip of the rod 
evaporation material so that the rod material which is consumed with 
evaporation can be fed. 
In the above-described embodiment, the vacuum evaporation device that the 
hot-cathode filament is provided as the electron source around the tip of 
the rod evaporation material removes the excessive radiation heat, 
conductive heat, ions, scattered electrons and secondary electrons which 
are parts to form the evaporation section but detrimental to the 
deposition by forming into a structure the conductive cooling member of 
the good heat conductive metal of a continuous body of copper or copper 
alloy or aluminum or aluminum alloy which is partly contacted with the 
atmosphere, so that the screening electrode and its exterior are covered 
in parallel to the rod evaporation material. And, the ion current only is 
removed as a current through the screening electrode while removing, the 
evaporation rate is monitored, the liquid nitrogen cooling is not 
required, and the composite rod evaporation material is used as a single 
evaporation source, so that a compound semiconductor or alloy can be 
formed easily on a substrate. Thus, a simple and inexpensive 
high-performance electron impact heating evaporation model is provided to 
solve the described disadvantages. 
The invention is not limited to the rod evaporation material, but a 
plurality of rod evaporation materials may be arranged side to side or may 
be formed into a plate to provide the evaporation source. And, the 
evaporation source is not limited to be disposed vertically in the vacuum 
device, but may be arranged to evaporate horizontally or vertically. In 
summary, in a vacuum evaporator that a solid substance provided within a 
vacuum vessel is melted and evaporated or sublimed by electron impact 
heating to form atomic or molecular beams and to adhere onto a separately 
provided deposition substrate, a conductive cooling member of a good heat 
conductive metal such as a continuous body of copper or copper alloy or 
aluminum or aluminum alloy which is partly in contact with the atmosphere 
is provided on the periphery of the rod evaporation material and 
hot-cathode filaments in parallel to the rod evaporation material 
inclusively to decrease the dissipation of radiation heat into a vacuum 
vessel; and heat absorbed from the hot-cathode filaments and a tip of the 
rod evaporation material by the conductive cooling member is quickly 
conducted through the conductive cooling member and discharged to the 
atmosphere to prevent the temperature of an electron impact heating part 
from increasing and to prevent the increase of the gas discharge due to 
the heat dissipation from the electron impact heating part. And, the 
screening electrode is provided around the electron impact heating part to 
prevent the dissipation of the electrons and ions produced from the 
evaporation tip of the rod evaporation material and the hot-cathode 
filament. This screening electrode is made to an electrical potential 
lower than the hot-cathode filament's potential, and an ion current 
flowing to this electrode is detected so that the atomic beams and the 
evaporation rate of the evaporated atomic beams can be monitored. Besides, 
for the rod evaporation material, by bundling a plurality of different 
materials or by integrally overlaying a plurality of rod pipes into a rod 
shape to form a composite rod evaporation member, a single evaporation 
device may have a different structure as far as it can form a compound 
semiconductor or alloy on the melting evaporation source or the deposition 
substrate. 
The invention described in claim 1 relates to a vacuum evaporator that a 
solid substance provided within a vacuum vessel is melted and evaporated 
or sublimed by electron impact heating to form atomic or molecular beams 
and to adhere onto a separately provided deposition substrate, 
characterized in that: 
hot-cathode filaments are provided as an electron source around a tip of a 
rod evaporation material; a conductive cooling member of a good heat 
conductive metal which is partly in contact with the atmosphere is 
provided on the periphery of the rod evaporation material and the 
hot-cathode filaments in parallel to the rod evaporation material to 
decrease the dissipation of radiation heat produced from the hot-cathode 
filaments and a tip of the rod evaporation material into a vacuum vessel; 
and heat absorbed by the conductive cooling member is quickly conducted 
through the conductive cooling member and discharged to the atmosphere to 
prevent the temperature of an electron impact heating part from increasing 
and to prevent the increase of the gas discharge due to the heat 
dissipation from the electron impact heating part. 
The invention described in claim 2 relates to a vacuum evaporator according 
to claim 1, wherein a screening electrode is provided between the electron 
impact heating part and the conductive cooling member to prevent the 
dissipation of electrons and ions generated from the evaporation tip of 
the rod evaporation material and the hot-cathode filaments. 
The invention described in claim 3 relates to a vacuum evaporator according 
to claim 2, wherein the screening electrode is made to be an electrical 
potential lower than the hot-cathode filaments' potential, and an ion 
current flowing to the screening electrode is detected to monitor and 
detect evaporation intensities of evaporated atomic beams and molecular 
beams. 
The invention described in claim 4 relates to a vacuum evaporator according 
to claim 2, wherein an atomic and molecular beam discharge port formed on 
the screening electrode has a meshed structure. 
The invention described in claim 5 relates to a vacuum evaporator according 
to any one of claims 1 to 4, wherein the rod evaporation material is 
formed by bundling a plurality of different materials into one body. 
Therefore, the high-temperature radiation heat and the conductive heat from 
the hot-cathode filament and the tip of the evaporation material do not 
enter an analyzer provided on the vacuum vessel wall or within the vacuum 
vessel but are quickly discharged outside through the conductive cooling 
member, and vacuum degradation due to the dissipation of various electrons 
and ions containing the backscattered electrons can be prevented, the 
deposited film can be prevented from being damaged, and water cooling or 
liquid nitrogen cooling is not required. 
In addition, the intensity of the molecular beams at the time of depositing 
the evaporated atomic beams can be monitored, and a plurality of different 
rod evaporation materials are integrally bundled to form the rod 
evaporation member, so that there is provided a vacuum evaporator having 
quartet effects, which is a single evaporation device but can easily form 
a compound semiconductor or alloy on a deposition substrate.