Method for supplying vacuum evaporation material

A method for supplying a vacuum evaporation material provides a first vacuum evaporation material accommodated in a crucible and heated by electron beams so as to be fused. When a thin film is formed by adhering vapor generated form the first material to a substrate, a second long supply vacuum evaporation material is fed in a positive direction, the second material moving from above a liquid surface of the first material toward the first material which has fused in the crucible. An average feed speed of the second material is maintained by alternately switching a feed direction between the positive direction and the negative direction, in which the second material moves backward. An apparatus for supplying the vacuum evaporation material in which the first material is supplied to the crucible by alternately switching the feed direction between the positive and the negative directions, includes an operating circuit for performing the following calculation based on an instruction of an average supply speed (V.sub.AV) for feeding the second material: EQU (V.sub.AV)=(F-B)/(T.sub.FD +T.sub.BD +T.sub.FS +T.sub.BS). F is a feed amount in the positive direction, B is a feed amount in the negative direction (constant), B>0; T.sub.FD : net feed period of time in the positive direction, T.sub.FS is a suspension period of time in the positive direction feed, T.sub.FS .gtoreq.0. T.sub.BD is a net feed period of time in the negative direction (constant), and T.sub.BS is a suspension period of time in the negative direction feed (constant), T.sub.BS .gtoreq.0. A driving circuit drives the second material according to each calculated value calculated by the operating circuit.

BACKGROUND OF THE INVENTION 
The present invention relates to a method for supplying a vacuum 
evaporation material to a position to be heated in forming a thin film on 
a substrate. 
In order to form a thin film on a long film and manufacture a functional 
film serving as the material of a capacitor, a magnetic tape or the like 
by means of vacuum evaporation, it is necessary to generate a large 
quantity of vapor over a long period of time. To this end, it is necessary 
to successively supply a vacuum evaporation material to a position to be 
heated where a member such as an evaporation crucible is located. 
Conventionally, several methods as shown below have been used to 
successively supply a vacuum evaporation material. 
According to the first method, as shown in "Thin Film Handbook" (published 
by Ohm Publishing Co., Ltd. in 1983, page 105) edited by Japan Science 
Promotion Association, a vacuum evaporation material in the form of a wire 
is supplied to a crucible. 
This method is applicable to a vacuum evaporation material of a ductile 
material such as Al, Ni, or Cu which can be easily formed into a wire. But 
this method has a problem in that it is very difficult to form a brittle 
material such as Cr into a wire. In addition, a rigid material such as a 
material of a magnetic film, for example an alloy of Co-Cr or an alloy of 
Co-Cr-Ni, is not brittle and could be formed into a wire, but cannot be 
easily processed, so that the manufacturing cost is high and not of 
practical use. 
According to the second method, the brittle and rigid materials as 
described above are supplied in the form of a bar. 
The problem with the supply of a vacuum evaporation material in the form of 
a bar is described using FIGS. 1 through 7. In FIG. 1, reference numeral 1 
denotes a vacuum evaporation material, accommodated in a crucible 2, which 
is heated by electron beams scanned in the direction, for example, shown 
by the arrow (E) and fuses. Reference numeral 3 designates a bar-shaped 
long supply vacuum evaporation material, (hereinafter referred to as bar 
material) 11, 12, 13 denote rollers for guiding the bar material 3, and 14 
denotes a driving roller. A motor 20 is installed either in a vacuum 
chamber (not shown), thus directly driving the driving roller 14 or on the 
outside, thus driving the driving roller 14 through a known rotation 
transmitting unit. The driving roller 14 is driven by the motor 20 in CCW 
direction, and the driving roller 14 and the rotation roller 11 sandwich 
the bar material 3 therebetween, the driving roller 14 thus feeding the 
bar material 3 in the direction shown by the arrow (A) at a constant speed 
from above the liquid surface 4 toward the liquid surface 4 of the vacuum 
evaporation material 1, which has fused. Reference numerals 15 and 16 
denote covers for preventing the vapor of the vacuum evaporation material 
1 from adhering to the rollers 11, 12, 13, and 14. 
In order to form a thin film 9 on a substrate 8 positioned above the 
crucible 2 over a long period of time by the above construction, the bar 
material 3 is supplied to supplement a vaporization-reduced amount of the 
vacuum evaporation material 1 accommodated in the crucible 2. 
The behavior of the end 5 of the bar material 3 which takes place after the 
end 5 contacts the liquid surface 4 is described based on FIGS. 2 through 
5. FIG. 2 is a view showing the end 5 of the bar material 3, which has 
just contacted the liquid surface 4, and this condition is supposed to be 
condition (a). In this condition (a), the end 5 starts melting as a result 
of heat absorption from the liquid surface 4, thus fusing into a solution 
6 of the vacuum evaporation material 1 as shown by the arrow (R) of 
condition (b) of FIG. 3. At this time, heat is transmitted to the end 5 in 
the direction opposite to the direction shown by the arrow (R), and 
consequently the fusion of the end 5 progresses. With the progress of the 
fusion, the distance (g) between the liquid surface 4 and the end 5 of the 
bar material 3 becomes long, so that it becomes difficult for heat to be 
transmitted from the liquid surface 4 to the end 5. As a result, the 
fusion amount of the end 5 is reduced as shown by condition (c) of FIG. 4, 
and the amount of the solution 6 becomes small. Consequently, it becomes 
more difficult for the end 5 to melt, with the result that the fusion 
stops as shown by condition (d) of FIG. 14. The bulge of the end 5 of FIG. 
5 is a droplet 6A of the solution 6. 
Meanwhile, the bar material 3 is continuously fed in the direction shown by 
the arrow (A), but the fusion speed of the end 5 from the condition (a) 
until the condition (d) is faster than the bar material feeding speed. 
Therefore, a gap (D) is formed as shown by the condition (d). Since the 
bar material 3 is continuously fed, the gap (D) becomes small with the 
elapse of time, thus resulting in the condition (a). Thus, this cycle is 
repeated. That is, although the bar material 3 is continuously fed, the 
bar material 3 is intermittently fed to the liquid surface 4. 
While the end 5 is fusing with the liquid surface, the end 5 absorbs heat 
from the liquid surface 4, so that the temperature of the liquid surface 4 
lowers. As a result, the evaporation speed lowers and the evaporation 
speed cyclically fluctuates with the elapse of time, as shown in FIG. 6. 
The distance (D) of the condition (d) becomes great as the diameter of the 
bar material 3 becomes large. The reason is that, supposing that the 
configuration of the solution 6 is substantially a cylinder, as the 
diameter of the cylinder becomes large, the ratio of surface area of 
cylinder to volume of cylinder becomes small. Therefore, the ratio of heat 
quantity which escapes from the surface of the cylinder by radiation to 
the heat quantity which is transmitted from the liquid surface 4 to the 
top end 5 through the solution 6 becomes small, so that it takes long for 
the end 5 to fuse. Accordingly, when the diameter of the bar material 
becomes large, both the cycle T.sub.L and fluctuation width H.sub.L of the 
evaporation speed shown in FIG. 6 become large. 
This method has a problem in that due to the fluctuation of the evaporation 
speed, the film thickness is not uniformly formed in the direction in 
which vacuum evaporation is carried out while a substrate 8, such as a 
film, is moving above the crucible 2, forming a film while the substrate 8 
is moving. 
In order to overcome the above-described problem, according to the third 
method shown in FIG. 7, the bar material is supplied to the crucible after 
it is fused. This method is described using the reference numerals of FIG. 
1 concerning the same parts of FIG. 7. In FIG. 7, electron beams 7B for 
fusing the bar material are irradiated onto the end 5 of the bar material 
3 to fuse, and unlike the second method, the temperature of the liquid 
surface 4 is not lowered by the supply of the solution 6 to the liquid 
surface 4, so that the evaporation speed does not fluctuate. Accordingly, 
if a film is formed by traveling the substrate 8 above the crucible 2 in a 
direction perpendicular to the sheet surface of FIG. 7, the film thickness 
of a thin film 9 does not become nonuniform. 
Next, a description is made with regard to a condition for constantly 
maintaining the composition ratio of an alloyed thin film formed on a 
substrate when the vacuum evaporation material 1 consists of an alloy of 
Co-Cr, which is a material, such as a magnetic material, composed of 
components different in evaporation speeds. The evaporation speed of Cr is 
faster than that of Co by three to four times, so that supposing that the 
content of Cr of a thin film to be formed is (M) and the content of Cr of 
a thin film material 1 is (Y), it is required that M is 3 to 4 times more 
than Y, that is, M=(3.about.4)Y. The content of Cr of vapor generated from 
the liquid surface 4 is equal to (M). Accordingly, if a material with Cr 
content of (M) and equal to an evaporated amount can be supplied, a thin 
film with Cr content of (M) can be continuously formed with the amount of 
the thin film material 1 in the crucible 2 kept to be constant. 
However, in the construction of FIG. 7, the solution 6 formed by the 
irradiation of the electron beams 7B onto the end 5 of the bar material 3, 
with a Cr content of (M), stays at the end 5 of the bar material 3 by its 
surface tension, thus becoming a large droplet 6B. Thereafter, the droplet 
6B does not become resistant to the gravity, thus falling to the liquid 
surface 4. The solution 6 falls in one droplet 6C or in two droplets 6C 
when the droplet 6C which stays on the end 5 of the bar material 3 becomes 
too great. Supposing that the diameter of the bar material is Db, in terms 
of the length of the bar material, the volume of the droplet 6C is Db/15 
when the droplet 6C is small or the volume of a column corresponding to 
Db/3 when the solution falls in two droplets 6C. Thus, when such a large 
quantity of droplet 6C with Cr content of (M) falls to the liquid surface 
4, the density of Cr on the liquid surface 4 becomes high and the Cr 
content in vapor generated from the liquid surface 4 becomes greater than 
(M). This method has a problem in that the composition ratio among 
components of an alloyed thin film fluctuates in the travel direction of a 
substrate in forming a thin film by traveling the substrate above the 
crucible because the droplet 6C falls intermittently. 
SUMMARY OF THE INVENTION 
Accordingly, an essential object of the present invention is to resolve the 
problems described above and to provide a novel method for supplying a 
vacuum evaporation material and an apparatus therefor. 
In accomplishing this and other objects, according to one aspect of the 
present invention, there is provided a method for supplying a vacuum 
evaporation material, in which a first vacuum evaporation material 
accommodated in a crucible is heated to be fused, and when a thin film is 
formed by adhering vapor generated from the first material to a substrate, 
a second vacuum evaporation material, which is long, is fed in a positive 
direction on an average of feed speed of the second material by 
alternately switching a feed direction thereof between the positive 
direction and a negative direction, supposing that a direction in which 
the second material moves from above the liquid surface toward the first 
material which has fused in the crucible is the positive direction and a 
direction in which the second material moves backward therefrom is the 
negative direction. 
According to still another aspect of the present invention, there is 
provided a method for supplying a vacuum evaporation material, comprising 
the steps of: 
a vacuum evaporation material feed means for feeding a second vacuum 
evaporation material, which is long, in a condition in which the second 
material is fed in a positive direction on an average of feed speed of the 
second material by alternately switching a feed direction thereof between 
the positive direction and a negative direction, supposing that a 
direction in which the second material moves from above the liquid surface 
toward a liquid surface of a first vacuum evaporation material which has 
fused in a crucible is the positive direction and a direction in which the 
second material moves backward therefrom is the negative direction; and 
changing the temperature of the vicinity of an end of the second material 
being fed toward the liquid surface. 
According to a further aspect of the present invention, there is provided a 
method for supplying a vacuum evaporation material, in which in forming a 
thin film by heating and melting a first vacuum evaporation material 
accommodated in a crucible and adhering vapor generated from the first 
material to a substrate, an angle formed by a liquid surface of the first 
material with respect to a feed direction in which a second vacuum 
evaporation material, which is long, is fed from above the liquid surface 
toward the liquid surface is different from 90.degree. and the second 
material is rotated around an axis thereof or around an axis a 
predetermined distance offset from the axis thereof. 
According to a still further aspect of the present invention, there is 
provided a method for supplying a vacuum evaporation material in which in 
forming a thin film by heating and melting a first vacuum evaporation 
material accommodated in a crucible and adhering vapor generated from the 
first material to a substrate, a crank mechanism is fed from above the 
liquid surface toward a liquid surface of the first material accommodated 
in the crucible while the crank mechanism causes a second vacuum 
evaporation material, which is long, to make a reciprocating motion of 
moving toward the first material which has fused in the crucible and 
moving away from the first material.

BEST MODE FOR CARRYING OUT THE INVENTION 
Before the description of the present invention proceeds, it is to be noted 
that like parts are designated by like reference numerals throughout the 
accompanying drawings. 
Embodiments of the present invention are described. In the illustrations, 
the same parts as those of the conventional art are denoted by the same 
reference numerals. 
FIGS. 8 through 11 are illustrations of the first embodiment of the present 
invention. In FIG. 8, reference numeral 20 denotes the motor to be driven 
by a driving circuit 21, and the motor 20 rotates the driving roller 14. 
Reference numeral 22 designates an arithmetic circuit for performing an 
operation of the speed pattern of the motor 20 based on an instruction 24 
of the average feed speed V.sub.AV of the bar material 3 and data stored 
in a memory 23, thus outputting the result of the operation to the driving 
circuit 21 as a speed instruction 25. 
Next, an example of a speed pattern operation is shown in FIG. 9. In FIG. 
9, the feed speed (v) shows the feed speed of the bar material 3 in FIG. 
8. Positive (+) designates the speed in the direction shown by the arrow 
(A) in FIG. 8, and negative (-) indicates the speed in the direction 
opposite to the direction shown by the arrow (A). The configuration of the 
speed pattern is a trapezoidal waveform in both the positive and negative 
directions. In order to simplify the operation, the maximum speed 
(V.sub.MAX) is the same in both the positive and negative directions, and 
the acceleration speed and deceleration speed from 0 until V.sub.MAX, 
namely, angles .alpha..sub.1, .alpha..sub.2, .alpha..sub.3, and 
.alpha..sub.4, are identical to each other. Suspension times T.sub.FS and 
T.sub.BS are provided so that an excessive force is applied to a bar 
material supply mechanism comprising rollers and the motor shown in FIG. 8 
when the feed speed changes from the positive direction to the negative 
direction and from the negative direction to the positive direction or 
provided as necessary period of time for performing the operation, 
however, suspension time T.sub.FS and T.sub.BS are not necessarily 
provided. 
The area of the trapezoidal waveform in the positive direction shows the 
feed distance (F) in the direction shown by the arrow (A). The area of the 
trapezoidal waveform in the negative direction shows the feed distance (B) 
in the direction opposite to the direction shown by the arrow (A). 
T.sub.FD and T.sub.BD indicate the net feed period of time in the positive 
direction and the net feed period of time in the negative direction, 
respectively. In the above, the average feed speed V.sub.AV is expressed 
by an equation (1): 
EQU V.sub.AV =(F-B)/(T.sub.FD +T.sub.BD +T.sub.FS +T.sub.BS) (1) 
T.sub.FD can be calculated based on an equation (2): 
EQU T.sub.FD =T.sub.BD +[(F-B)/V.sub.MAX ] (2) 
V.sub.AV is set so that similarly to the known art, the vacuum evaporation 
material 1 in the crucible 2 cannot be reduced, i.e., an evaporation 
amount can be supplemented. 
When the bar material 3 is driven in the speed pattern shown in FIG. 9 with 
the distance (B) equal to or greater than the distance K.sub.1 
(=D/sin.theta..sub.1) in FIG. 5, i.e., with the bar material 3 fed in the 
negative direction until the end 5 thereof separates from the liquid 
surface 4, the bar material 3 is in the condition (a) of FIG. 2 at time 
T.sub.1 in FIG. 9, supposing that the bar material 3 is in the condition 
(d) of FIG. 5 at time 0 in FIG. 9, and then, the bar material 3 fuses with 
the solution of the vacuum evaporation material 1 in the order of the 
condition (b) of FIG. 3, then condition (c) of FIG. 4, and the condition 
(d) of FIG. 5 with the elapse of time from time T.sub.1 until time T.sub.2 
in FIG. 9. It is assumed that the speed pattern is set so that one cycle 
T.sub.S of the speed pattern is, for example, 1/10 of one cycle T.sub.L of 
the conventional art shown in FIG. 6. Then, the amount of the bar material 
3 which fuses into the solution of the vacuum evaporation material 1 in 
one cycle can be made to be 1/10 of the amount which is conventionally 
used. The heat quantity to be absorbed by the end 5 from the liquid 
surface 4 becomes small with the reduction of the fusion amount of the bar 
material 3, so that the temperature reduction of the liquid surface 4 
becomes small. Consequently, the reduction of the evaporation speed 
becomes small. The evaporation speed fluctuates in the cycle T.sub.S with 
the elapse of time as shown in FIG. 10. However, the fluctuation width Hs 
can be made to be approximately 1/10 of the width H.sub.L of the 
conventional art. Therefore, the uniformity of the film thickness can be 
improved in forming the film while the substrate is traveling. 
If a bar material consists of a plurality of components whose evaporation 
speeds are different from each other, the supply amount (F-B) of the bar 
material 3 can be easily made to be Db/100.about.Db/150 per reciprocation 
thereof because the movement of the bar material 3 in the feed distances 
(F) and (B) is controlled supposing that the diameter of the bar material 
is Db. In the third example of the known art shown in FIG. 7, as described 
previously, compared with the fact that the diameter of a droplet is in 
the range from Db/3 to Db/15, the vacuum evaporation material 1 can be 
supplied in a smaller amount by approximately one figure, so that the 
fluctuation of the composition ratio contained in vapor can be made to be 
small. As a result, the uniformity of the film thickness can be improved 
in forming the film while the substrate is traveling. p In the above 
example, the speed pattern is described using the trapezoidal waveform, 
however, the description of the speed pattern is not limited to that. A 
rectangular waveform, which simplifies a control, a sine wave of smooth 
acceleration and deceleration speeds, or any other waveform may be used. 
The cycle Ts may be determined so that the evaporation speed fluctuation 
width Hs which is decided by allowable film thickness fluctuation, becomes 
a required value. When the diameter of the bar material becomes great, the 
evaporation speed fluctuation width tends to become large because of the 
reason previously described, so that it is necessary to make the cycle Ts 
small. 
In the above example, the description is made with the distance (B) equal 
to or greater than the distance K.sub.1 (=D/sin.theta..sub.1) in FIG. 5, 
i.e., with the bar material 3 fed in the negative direction until the end 
5 separates from the liquid surface 4. Additionally, it is possible to 
feed the end 5 of the bar material 3 in the negative direction until the 
condition (c) of FIG. 4, namely, until the condition in which the end 5 is 
connected with the liquid surface 4 through a narrowed solution 6. In this 
case, the distance (B) is equal to the distance (K.sub.2). 
By doing so, the period of time required for the condition (a) of FIG. 2 to 
become the condition (c) of FIG. 4 through the condition (b) of FIG. 3 is 
very short compared with that of the known art, so that the amount of the 
bar material 3 which fuses into the solution 6 in one cycle is much 
smaller compared with the known art. By doing so, the end 5 of the bar 
material 3 and the liquid surface 4 are always connected with each other 
through the solution 6. As a result, the vibration of the liquid surface 4 
does not occur in feeding the bar material in the negative direction until 
the end 5 of the bar material 3 separates from the liquid surface 4, so 
that vacuum evaporation can be carried out in a stable condition. 
Next, second, third, and fourth embodiments of the present invention 
applicable to a wider vacuum evaporation condition are described. 
The second and third embodiments are effectively applied to the case in 
which thermal energy for heating the vacuum evaporation material 1 is 
great compared with the size of the crucible 2. In this condition, the 
vacuum evaporation material 1 becomes a solution, the temperature of which 
is fairly higher than its melting point. Then, when the bar material 3 
comes into contact with the liquid surface 4, it is easy for the bar 
material 3 to fuse, so that the fusion amount becomes great and the amount 
of a supply material which fuses into a liquid surface as a result of its 
contact with the liquid surface exceeds the amount of the forward movement 
of the supply material in the operation per one positive direction 
movement and one negative direction movement, namely, per one 
reciprocation thereof. As a result, as described with reference to FIG. 
11, the supply material does not come into contact with a liquid surface 
in an approximately equal amount for each reciprocation. Consequently, the 
vacuum evaporation speed fluctuates in a comparatively long cycle. 
FIG. 11 shows the fusion condition of the bar material 3 reciprocatingly 
supplied, in which an operation is repeated in the order of conditions f', 
g', h' . . . p', q', f', g', h'. The conditions f', h', j', . . . 
correspond to T.sub.1 of FIG. 9, namely, the condition in which the bar 
material has completed its forward movement. The conditions g', i', k', 
correspond to T.sub.2 of FIG. 9, namely, the condition in which the bar 
material has completed its backward movement. The condition changes from 
the condition of FIG. 2 to that of FIG. 5 when the bar material moves 
backward after the droplet 6A comes into contact with the liquid surface 
4, i.e., when the bar material moves from the condition f' to the 
condition g' or from the condition h' to the condition i'. In order to 
make the description understandable, the bulge of the droplet 6A in FIG. 
11 is larger than that shown in FIG. 5. Reference letter (Me) denotes the 
amount of the bar material 3 which fuses into the liquid surface 4 from 
the time when the bar material 3 comes into contact with the liquid 
surface 4 until the time when the ba material 3 separates from the liquid 
surface 4. As shown in FIG. 11, it is assumed that Me&gt;(F-B), i.e., the 
amount of a supply material which fuses into a liquid surface as a result 
of its contact with the liquid surface exceeds the amount of the forward 
movement of the supply material in the operation of one positive direction 
movement and one negative direction movement, namely, one reciprocation. 
Since the bar material 3 repeats a reciprocating operation, the operations 
as shown in FIGS. 2 through 5 are repeated. Since Me&gt;(F-B), the contact 
amount between the liquid surface 4 and the bar material 3 decreases 
gradually and finally, the bar material 3 does not come into contact with 
the liquid surface 4 as shown by the condition p'. When the contact amount 
is great, the fusion amount increases and the temperature of the liquid 
surface 4 lowers greatly, so that the evaporation speed becomes low. With 
the reduction of the contact amount, the fusion amount becomes smaller and 
the temperature rises, so that the problem arises in that the evaporation 
speed fluctuates as shown by an amplitude H.sub.A in the cycle of T.sub.A 
of FIG. 10. If the supply material is composed of a plurality of 
components whose evaporation speeds differ from each other, the supply 
material contains materials whose evaporation speed are high, more than 
those contained in the solution in the crucible, as described previously. 
Therefore, when the amount of the bar material which fuses into the liquid 
surface changes with the change of the contact amount between the bar 
material and the liquid surface as described previously, the composition 
ratio of vapor generated from the liquid surface changes, with the result 
that the composition ratio in the travel direction fluctuates when the 
film is formed while the substrate is traveling. 
FIG. 12 shows a feed speed pattern of the bar material 3 according to the 
second embodiment of the present invention, intended to solve this 
problem, and this feed speed pattern is characterized by T.sub.BS 
&gt;T.sub.FS. 
Since T.sub.FS is short, the contact period of time between the liquid 
surface and the bar material becomes short, so that the amount of the bar 
material which fuses into the liquid surface can be reduced when both are 
in contact with each other. On the other hand, since T.sub.BS is long, the 
denominator of the equation (1) becomes large, so that (F-B) of the 
equation (1), namely, the supply amount per reciprocation of the bar 
material can be increased. Therefore, owing to the synergistic effect, the 
amount of the supply material which fuses into a liquid surface as a 
result of its contact with the liquid surface does not exceed the amount 
of the forward movement of the supply material in the operation in one 
positive direction movement and one negative direction movement, namely, 
per one reciprocation thereof. That is, the supply material comes into 
contact with the liquid surface in an approximately equal amount for each 
reciprocation, which can be satisfied. Therefore, the uniformities of a 
film thickness and composition ratio can be improved in forming the film 
while the substrate is traveling. 
FIGS. 13 and 14 are, respectively, the construction view and the enlarged 
view according to the third embodiment of the present invention, provided 
to solve this problem. The same parts of FIGS. 13 and 14 as those of FIG. 
8 are denoted by the same reference numerals as those of FIG. 8. In FIGS. 
13 and 14, reference numeral 30 denotes a driving roller driven by the 
motor 20, and 31 designates a rotation roller for guiding the bar material 
3. Reference numerals 32 and 33 represent cooling rotation rollers 
rotatably supported by shafts 36 and 37 constructed around cooling fluid 
paths 34 and 35, respectively. Although not shown, the cooling rotation 
roller 33 is pressed against the cooling rotation roller 32 by a spring or 
its dead weight. The cooling rotation rollers 32 and 33 are drum-shaped so 
that they come into contact with the bar material 3 in a great area to 
increase their efficiency in cooling the bar material 3. Graphite or 
molybdenum disulfide is provided between the shaft 36 and the cooling 
rotation roller 32 and between the shaft 37 and the cooling rotation 
roller 33 for lubrication, as required. 
According to the construction in FIG. 13, the bar material 3 moves away 
from the liquid surface 4 and the end 5 thereof stops at a position Re, so 
that the end 5 is cooled by the respective rotation rollers 32 and 33. As 
a result of the cooling, the bar material 3 is fed toward the liquid 
surface 4, and when it comes into contact with the liquid surface 4, it is 
hard for the temperature of the end 5 to rise, so that the amount of the 
end which fuses into the liquid surface 4 can be reduced. Accordingly, 
similarly to the second embodiment, the uniformities of a film thickness 
and composition ratio can be improved in forming the film while the 
substrate is traveling. 
With the condition T.sub.BS &gt;T.sub.FS similar to the second embodiment, and 
when the suspension period of time of the bar material 3 being long after 
the bar material 3 moves away from liquid surface 4, the end 5 of the bar 
material 3 is sufficiently cooled by the cooling rotation rollers 32 and 
33, so that the amount of the bar material 3 which fuses into the liquid 
surface 4 can be effectively reduced. 
In the above example, two rotation rollers are used as the cooling members 
which come into contact with the bar material 3. However, one cooling 
rotation roller suffices if it has a sufficient cooling capacity. The 
cooling member is not necessarily rotated, and a fixed member cooled by 
water may be employed if there is no problem with the friction between the 
cooling member and the bar material 3. 
The fourth embodiment is effective for the case in which, conversely to the 
second and third embodiments, heat energy for heating the vacuum 
evaporation material 1 is small compared with the size of the crucible 2, 
a cooled metal container made of such as Cu is used as the crucible 2 
instead of ceramic, or the melting point of the vacuum evaporation 
material 1 is high. In such a condition, the vacuum evaporation material 1 
consists of a solution whose temperature is not so high compared with its 
melting point. In this case, when the bar material 3 comes into contact 
with the liquid surface 4, the heat of the liquid surface 4 is absorbed by 
the bar material 3, so that the temperature of the liquid surface 4 
rapidly lowers and the evaporation speed lowers noticeably. 
FIG. 15 is the construction view of the fourth embodiment which solves this 
problem. In FIG. 15, reference numeral 7C denotes electron beams 
irradiated to the end 5 of the bar material 3. According to this 
construction, the bar material 3 moves away from the liquid surface 4 and 
the end 5 thereof stops at the position Re and the top end 5 is heated by 
the electron beams 7C. 
With the rise of the temperature as a result of the heating, the bar 
material 3 is fed toward the liquid surface 4, thus coming into contact 
with the liquid surface 4, with the result that the end 5 does not absorb 
heat from the liquid surface 4 so much, and it is hard for the temperature 
of the liquid surface 4 to lower. Therefore, the lowering of the 
evaporation speed can be reduced. Accordingly, the uniformity of a film 
thickness can be improved in forming the film while the substrate is 
traveling. The fourth embodiment is effective as well if T.sub.BS 
&gt;T.sub.FS, similar to the second embodiment. 
Next, the fifth, sixth, and seventh embodiments of other driving methods of 
the present invention will be described. FIGS. 16 and 17 are, 
respectively, the construction view and the enlarged view according to the 
fifth embodiment of the present invention. In FIGS. 16 and 17, reference 
numerals 40, 41, 42, 43, and 44 denote rotation rollers for guiding the 
bar material 3 and 45 denotes a driving roller. The respective rollers 
come into contact 
with the bar material 3 at an intersection angle of .beta.. In FIG. 16, the 
rotation rollers 40 and 41 are partly broken away to make the construction 
thereof understandable. 
The driving roller 45 is driven by the motor 20 in the direction shown by 
the arrow (G) and the bar material 3 is sandwiched between the driving 
roller 45 and the rotation rollers 40 and 41, and the bar material 3 is 
fed in the direction shown by the arrow (A) at a constant speed toward the 
liquid surface 4 of the vacuum evaporation material 1, which has melted 
while the bar material 3 is rotating around its axis. Supposing that the 
diameter of the bar material 3 is Db, the feed amount of the bar material 
3 per rotation thereof is .pi..multidot.Db.multidot.tan.beta.. 
When the end 5 of the bar material 3 comes into contact with the liquid 
surface 4, it melts into a conical surface 46 as shown in FIG. 16, because 
the bar material 3 is rotating. The contact of the conical surface 6 with 
the liquid surface 4 is a line contact. In the conventional method shown 
in FIG. 1, since the bar material is not rotated, the end 5 thereof is 
flat and the contact with the liquid surface 4 is of a face contact. Since 
heat is transmitted from the liquid surface 4 to the end 5 less in the 
line contact than in the face contact, the amount of the fusion of the end 
5 of the bar material 3 into the solution of the vacuum evaporation 
material 1 is less. Consequently, similar to the above description, the 
temperature lowering of the liquid surface 4 is small, so that the 
lowering of the evaporation speed is small. Thus, the uniformity of a film 
thickness can be improved. 
FIG. 18 is the construction view of the sixth embodiment of the present 
invention. In FIG. 18, reference numeral 50 denotes a rotation guide 
having an opening 51 for slidably guiding the bar material 3 in the 
lengthwise direction thereof, and the rotation guide 50 is supported by a 
bearing 52 and a bearing housing 53 and rotated by a motor 20A around a 
rotational axis 54. Reference numeral 55 denotes a flange for preventing 
vapor of the vacuum evaporation material 1 from permeating into the inside 
of the covers 15 and 16. Reference numeral 56 denotes a feed rod driven by 
a means (not shown) in the direction shown by the arrow (A) at a constant 
speed. Reference numeral 57 denotes a rotor rotatably supported by a 
bearing 58 which can receive both radial and thrust loads applied to the 
rod 56. The rear end 3B of the bar material 3 is fixed to the rotor 57 
through a bolt 59. 
Next, the operation of this construction will be described. 
Supposing that the bar material 3 is pressed by the rod 56 in the direction 
shown by the arrow (A) at a constant speed while the bar material 3 is 
rotated by the rotation guide 50, the end 5 of the bar material 3 makes a 
spiral motion. If the eccentric amount (e) of the bar material 3 from the 
rotation axis 54 is the radius of the bar material 3 or more, the end 5 of 
the bar material 3 separates from the liquid surface 4 when the bar 
material 3 is placed at a position shown by the broken lines after it 
makes a half rotation from a position shown by the solid lines of FIG. 18. 
If the eccentric amount (e) is the radius of the bar material 3 or less, 
the end 5 of the bar material 3 and the liquid surface 4 can be always 
connected with each other through a narrowed solution 6D as shown in FIG. 
19. Therefore, this embodiment can perform material supply corresponding 
to the first embodiment, in which speed pattern of FIG. 9 is shown by a 
sine wave, T.sub.FS =T.sub.BS =0, the cycle Ts is the rotation cycle of 
the rotation guide 50, and (F-B) is the feed amount of the rod 56 per 
rotation of the rotation guide. Accordingly, an advantage similar to that 
of the first embodiment can be obtained. 
FIG. 20 is the construction view according to the seventh embodiment of the 
present invention. The same parts of FIG. 20 as those of FIG. 18 are 
denoted by the same reference numerals as those of FIG. 18. Reference 
numeral 60 denotes a self-aligning ball-and-roller bearing with its 
periphery fixed to an opening 72 of a rotation guide 70. The bar material 
3 is slidably guided in the lengthwise direction thereof through the inner 
peripheral surface of an opening 61. Accordingly, no problems occur even 
if the rotation axis of the rotation guide 70 and the bar material 3 are 
not parallel with each other. Reference numeral 62 denotes a feed rod 
similar to the above-described feed rod 56. Reference numeral 63 denotes a 
mounting member constructed by fixing the rear end 3B of the bar material 
3 by the bolt 59. Reference numeral 65 denotes a known universal coupling 
which couples, with a cross type pin 66, a two-pronged arm 67 of the rod 
62 to a two-pronged arm 68 of the mounting member 63. The center point (X) 
of the cross type pin 66 is not necessarily provided in a prolonged line 
of the rotational axis of the rotation guide 70. 
When the rotation guide 70 is rotated in this construction similarly to 
FIG. 18 and the rod 62 is driven in the direction shown by the arrow (A) 
at a constant speed, the bar material 3 is moved with respect to the 
center point (X) of the cross type pin 66 of the universal coupling 65 as 
the supporting point of its pivotal motion, and the end 5 makes a spiral 
motion with respect to a line 71, formed by connecting the point (X) with 
the rotational center point (Z) of the rotation guide 70 in the direction 
shown by the arrow (A) of the self-aligning ball-and-roller bearing 60, 
serving as the center. That is, the direction of the line 71 is the 
material supply direction. Accordingly, when the rotation guide 70 makes a 
half rotation from the position shown by the solid line of FIG. 20, the 
bar material 3 is placed at the position shown by the broken lines, and 
similar to the construction of FIG. 18, material supply corresponding to 
the first embodiment can be accomplished and a similar advantage can be 
obtained. 
The differences among the fifth, sixth, and seventh embodiments are that 
the bar material 3 makes a rotation on its axis, makes both a rotation on 
its axis and a revolution on an axis, and makes a revolution on an axis, 
respectively. It is necessary in each of FIGS. 16, 18, and 20 that angles 
.theta..sub.2, .theta..sub.3, and .theta..sub.4 are not 90.degree.. 
FIG. 21 is the construction view according to the eighth embodiment of the 
present invention. The same parts of FIG. 21 as those FIG. 18 are denoted 
by the same reference numerals as those of FIG. 18. In FIG. 21, reference 
numeral 80 denotes a guide member in which an opening 81, having a narrow 
part in the middle, is formed, thus guiding the bar material 3 through the 
opening 81. Reference numeral 82 denotes a feed rod similar to the 
above-described feed rod 56, and the end thereof rotatably supports a 
shaft 84 to which a bevel gear 83B is fixed. Reference numeral 85 denotes 
a shaft having a bevel gear 83A, which engages the bevel gear 83B, fixed 
to the end of the shaft 85. The shaft 85 is supported by a bearing 86 and 
rotated by the motor 20A. Reference numeral 87 denotes a bracket, formed 
on the feed rod 82, which supports the bearing 86. Reference numeral 88 
denotes an eccentric ring which is fixed to the shaft 84 and rotates 
around the shaft 84, thus rotatably supporting a rotation ring 89 on the 
periphery thereof. Reference numeral 59 denotes the bolt for fixing the 
rear end 3B of the bar material 3 to the rotation ring 89. Accordingly, 
the shaft 84, the eccentric ring 88, the rotation ring 89, the bar 
material 3, and the opening 81 form a kind of crank mechanism, so that the 
bar material 3 is guided through the opening 81 by the rotation of the 
shaft 84, thus making a reciprocating motion at a stroke of 
2.multidot.R.sub.1. Reference letter R.sub.1 denotes the distance between 
the center of the shaft 84 and the center of the eccentric ring 88. 
Next, the operation of this construction is described. 
When the feed rod 82 is moved in the direction shown by the arrow (A) at a 
constant speed while the shaft 85 is being rotated by the motor 20A, the 
shaft 85 rotates the eccentric ring 88 through the bevel gears 83A and 83B 
and feeds the bar material 3 toward the liquid surface 4 while the bar 
material 3 is making a reciprocating motion. Accordingly, this 
construction can accomplish material supply corresponding to the first 
embodiment in which the speed pattern is shown by a sine wave in FIG. 9, 
and T.sub.FS =T.sub.BS =0. Therefore, an advantage similar to that of the 
first embodiment can be obtained. The feature of this embodiment is that 
it can be applied even if .theta..sub.5 =90.degree. unlike the fifth, 
sixth, and seventh embodiments. 
In all of the above embodiments, the description is made supposing that the 
bar is cylindrical and the number thereof is one. However, the bar may be 
a material of a square pillar, a plate, or other configurations, providing 
that it is long, and the number of the bar material may be plural. 
Instead of a driving roller, the bar material 3 or the feed rods 56, 62, 
and 82 may be fed by a chain, a belt or a rope which engage the bar 
material 3 or may be fed by a feed screw. 
If the width (W) of the crucible 2 of FIG. 8 is large, uniform supply to 
the crucible 2 in the entire width thereof can be accomplished by 
providing the above-described supply means in a plurality of places. The 
fluctuations of the evaporation speed of bar materials and the composition 
thereof caused by the contact thereof with the liquid surface and the 
fusion thereof can be reduced by differentiating the timing of the 
contacts of respective bar materials with the liquid surface. Further, it 
is possible to carry out the first through eighth embodiments by 
appropriately combining them. 
As described above, according to the method for supplying a vacuum 
evaporation material according to one aspect of the present invention, 
when the end of the vacuum evaporation material comes into contact with 
the liquid surface of the vacuum evaporation material after a supply 
material is fed in the positive direction, a fusion starts, and the bar is 
fed in the negative direction before the supply material fuses over a long 
period of time, with the result that the end of the supply material 
separates from the liquid surface or it is connected therewith through a 
narrowed solution. Thus, the supply material does not fuse into the 
solution in a large quantity. Therefore, since the temperature lowering of 
the liquid surface becomes small, the evaporation speed becomes also 
small. As a result, the reduction of a film thickness becomes small in 
forming the film while a substrate is traveling, so that the uniformity of 
the film thickness can be improved. 
If the supply material consists of a plurality of components whose 
evaporation speeds differ from each other, compared with the known method, 
the supply material can be supplied in a smaller amount by approximately 
one figure, so that the fluctuation of the composition ratio contained in 
vapor can be made to be small. As a result, the uniformity of the 
composition ratio in the travel direction of the substrate in forming the 
film while the substrate is traveling can be improved. 
According to the method for supplying a vacuum evaporation material as 
mentioned in still another aspect of the present invention, according to 
the above-described construction, if the temperature of the liquid surface 
of the vacuum evaporation material is high, the temperature of the end of 
the supply material is lowered by cooling the supply material in the 
vicinity of the top end thereof, so that it is difficult for the 
temperature of the supply material to rise when the supply material comes 
into contact with the liquid surface, and the amount of the supply 
material which fuses into the liquid surface can be reduced. Therefore, 
the amount of a supply material which fuses into a liquid surface as a 
result of its contact with the liquid surface does not exceed the amount 
of the forward movement of the supply material of the operation in one 
positive direction movement and one negative direction movement, i.e., one 
reciprocation. That is, the supply material comes into contact with the 
liquid surface in an approximately equal amount for each reciprocation. 
Therefore, the uniformities of a film thickness and composition ratio can 
be improved in forming the film while the substrate is traveling. 
On the other hand, if the temperature of the liquid surface of the 
evaporation material is low, the temperature of the end of the supply 
material rises by heating the supply material in the vicinity of the end 
thereof, so that the end of the supply material does not absorb heat as 
much from the liquid surface when the supply material comes into contact 
with the liquid surface, and it is difficult for the temperature of the 
liquid surface to lower. Therefore, in the condition in which the 
reduction of the evaporation speed is small, the uniformity of a film 
thickness can be improved in forming the film while the substrate is 
traveling. 
According to the apparatus for supplying a vacuum evaporation material as 
mentioned in the further aspect of the present invention, according to the 
above-described construction, when the supply material is rotated around 
its axis, the end of the supply material fuses into a conical 
configuration as a result of the contact of the top end thereof with the 
solution, and the supply material which comes into contact with the 
solution in a small area, so that the supply material is incapable of 
fusing into the solution in a great amount at a time. Accordingly, similar 
to one aspect of the present invention, since the reduction of the film 
thickness is small in forming the film while the substrate is traveling, 
the uniformity of the film thickness can be improved. Further, even if the 
supply material consists of a plurality of components whose evaporation 
speeds differ from each other, the uniformity of the composition ratio in 
the travel direction of the substrate in forming the film during the 
travel of the substrate can be improved. 
When the supply material is rotated around an axis offset from the 
above-described axis by a predetermined distance, similar to one aspect of 
the present invention, supposing that the direction in which the supply 
material moves toward the vacuum evaporation material which has fused in a 
crucible is the positive direction and the direction in which the supply 
material moves backward therefrom is the negative direction, the supply 
material is fed in the positive direction on an average of the feed speed 
of the supply material by alternately switching the feed direction thereof 
between the positive direction and the negative direction. Accordingly, 
the advantage of one aspect of the present invention can be obtained. 
According to the method for supplying a vacuum evaporation material as 
mentioned in a still further aspect of the present invention, according to 
the above-described construction, material supply similar to that of the 
further aspect of the present invention can be accomplished and similarly, 
and the advantage of the one aspect of the present invention can be 
obtained. 
Although the present invention has been fully described in connection with 
the preferred embodiments thereof with reference to the accompanying 
drawings, it is to be noted that various changes and modifications are 
apparent to those skilled in the art. Such changes and modifications are 
to be understood as included within the scope of the present invention as 
defined by the appended claims unless they depart therefrom.