JPH05339719A - Melting method of source metal for vacuum vapor deposition - Google Patents

Abstract

PURPOSE:To uniformly and wholly heat the crucible by decreasing the scanning rate and scanning length of an electron beam on the edge area of the crucible. CONSTITUTION:An electron beam from the electron gun 19 is deviated by a deviating magnetic field 23 to uniformly irradiate the source metal 17 in a crucible 15 considering that thermal emission is larger in the edge of the crucible than the center area. During the electron beam is repeatedly deviated for irradiation in the X direction or X-Y directions the scanning rate and length of the beam is changed stepwise in a manner that the beam scans slowly with short scanning length in the edge area and faster with long scanning length in the center area. Thereby, the source metal in the crucible which constitutes the vapor source is wholly heated to const. temp. and the obtd. vapor deposition film has uniform compsn. and thickness in both of the longitudinal and the width directions.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to metal deposition, and more particularly to a method for uniformly heating a crucible.

[0002]

2. Description of the Related Art In a vacuum chamber, an electron beam is generated from an electron gun, which is made into a spot by squeezing it by a lens and made to collide with a metal to be vaporized contained in a crucible and melted. A method of evaporating a metal vapor from a temperature metal to deposit it on a substrate is used. Such techniques are disclosed in Japanese Examined Patent Publication No. 3-41897 and Japanese Examined Patent Publication No. 3-3.
8340, JP-A-59-178626, JP-A-3-1.
No. 26823 and the like.

In a vacuum vapor deposition apparatus using such an electron gun, a high energy electron beam emitted from the electron gun is made to go straight toward a crucible. The crucible is usually in the shape of a rectangle elongated in the width direction of the substrate, and the electron beam is scanned in the length direction of the crucible under the action of a deflecting magnetic field or electric field in order to heat the metal surface of the crucible almost uniformly. For example, when manufacturing a vapor-deposited metal magnetic recording medium of oblique orientation type, C
O or Co alloy metal is housed in a crucible (boat) made of high-purity magnesia (MgO), and maximum 30kV from electron gun
With an accelerating voltage of a certain degree, the electron beam is directed straight toward the crucible and collides with the metal. At that time, the electron beam is scanned in the length direction of the crucible (and also in the width direction in some cases) to uniformly heat the metal (Japanese Patent Publication No. 3-38340).

In the above conventional vapor deposition method, sufficient adhesion strength of the vapor deposited metal to the substrate cannot be ensured, and a vapor deposited film having sufficient durability cannot be provided. The cause is that the electron beam power is about 120 to 150 kW (about 4 to 5 A at 30 kV).
In the above case, the electrons ejected from the surface of the molten metal together with the metal vapor and the electrons from the electron gun repel each other and the electrons cannot be converged, and the effective power cannot be increased to about 100 kW or more, and the vapor velocity is sufficiently improved. Because I couldn't. Here, the effective power is a power in a range in which the evaporation rate changes depending on the power of the electron gun (for example, 100 to 100).
If the evaporation rate does not change even after adding 150 kW, the maximum effective power is 100 kW). is there.

The effective electric power of the electron gun is arranged by intersecting the axis of the electron beam emitted by the electron gun with the axis connecting the center of the rectangular crucible and the center of the opening substantially at right angles, and by applying a magnetic field to the electron beam. It has been found that a substantial increase can be obtained by deflecting the light at a substantially right angle to form an image in the crucible.

More specifically, such an apparatus is provided opposite to the elongated rectangular crucible containing the metal to be vaporized, the electron gun for generating an electron beam directed in the crucible, and the crucible. Rotating drum, feeding and winding means for feeding a plastic substrate along the surface of the rotating drum, a mask provided along the surface of the rotating drum and having an opening partly facing the crucible, and the mask It can be realized in a vacuum vapor deposition apparatus including a shutter member for opening and closing. Such a vapor deposition apparatus can be used, for example, to obliquely vapor deposit Co or Co alloy on polyester (PET or the like) to manufacture a magnetic recording medium having diagonal anisotropy. At that time, a gas such as oxygen, carbon dioxide, nitrogen, ammonia, styrene or the like, particularly oxygen is introduced during vapor deposition for the purpose of adjusting magnetic properties (Japanese Patent Publication No. Sho 41-41897). That is, the gas is discharged from a supply nozzle having a slit-shaped outlet. A pressure equalizing tank may be used between the gas supply source and the nozzle to keep the flow rate distribution of the discharged gas constant.

In order to produce a vapor deposition film having a constant composition and thickness in both the width direction and the length direction, the entire raw material metal in the crucible constituting the vapor deposition source is heated to a constant temperature. is important. Usually, when the longitudinal direction of the crucible is X and the width direction is Y, the raw material metal in the crucible is linearly scanned with an electron beam over a predetermined length in the X direction, or as shown in FIG.
As described above, the scanning is performed in zigzag in the XY directions. Alternatively, as shown in JP-B-3-38340, the electron beam is scanned in the X direction with a triangular wave deflection signal at a constant speed and in the Y direction with a sine wave deflection signal. In the sine wave deflection signal, the scanning speed decreases at the end of the scan and overheating occurs. Therefore, in order to alleviate it, the range of the sine wave deflection in the Y direction is further sinusoidally modulated as a function of X, and the Y direction is changed. Average the heating of.

[0008]

None of the above electron beam scanning methods takes into account that the heat radiation in the peripheral portion of the crucible is larger than that in the central portion. In particular, since the deflection in the X direction is based on the triangular wave deflection signal, the beam scanning is performed at a constant speed, so that heat is insufficient at the end portion and the entire surface cannot be uniformly heated as shown in FIG. It can be easily imagined that the deflection speed inversely proportional to the temperature distribution shown in FIG. 3 may be set to compensate for this.

However, in order to generate such a smoothly changing deflection signal, it is necessary to set a deflection speed of about 200 points using a computer.
However, when a single electron gun is used, the convergence of the electron beam changes depending on the deflection angle, so it is necessary to redo the condition setting of the converging lens and the like each time. In order to prevent the control delay, it is necessary to increase the control speed, and it is necessary to take measures such as increasing the size of the computer.

Therefore, it is an object of the present invention to provide a method for melting a raw material metal using an electron beam scanning method capable of realizing uniform heating by an electron beam by a simple deflecting means.

[0011]

A method of melting a raw material metal in vacuum vapor deposition according to the present invention includes a rectangular crucible extending in the X direction or a raw material metal to be evaporated, and an electron beam focused on the raw material metal in the X direction. Alternatively, in a method of melting the metal by irradiating it while repeatedly deflecting in the XY direction, the scanning speed in the X direction for scanning the electron beam is slow at the end of the crucible and short and the scanning length is short at the center. It is characterized in that it is changed stepwise so as to be fast and to increase the scanning length. According to the present invention, the deflection speed of the electron beam in the X direction is only required to be several points, and there is an advantage that other conditions such as the correction of the converging lens according to the deflection speed can be set at the corresponding times.
Control is cheap and quick. For example, when the lengthwise dimension of the crucible is 0.8 m, a sufficient effect can be obtained even if the speed is 13 steps at maximum and usually 5 steps. In this case, the stairs may be spaced at regular intervals in the X direction, but as can be seen from FIG. 3, precise control is not required because the temperature change is gentle at the center of the crucible, so the scan length is short at the end and long at the center. Then, the number of steps can be reduced without impairing the heating uniformity. Next, even if uniform heating in the crucible is achieved, the film thickness at the edge of the substrate decreases if the length of the crucible in the X direction is not sufficiently long with respect to the width of the film substrate. Therefore, preferably, the electron beam scanning length in the X direction is 1, and
When the width of the substrate is W and l / W ≧ 1.3, the thickness of the metal film deposited on the substrate in the width direction of the substrate is constant.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a vapor deposition apparatus 1 of the present invention. However, the illustrated portion is housed in a vacuum chamber (not shown) and has a predetermined exhaust device. 3 is a rotating drum that rotates in the direction of the arrow (or the opposite direction),
A base film 5 made of polyester or the like, which constitutes a vapor deposition base, is passed around it, and is wound around a winding roll 7 from a pay-out roll 9 through the peripheral surface of the rotary drum 3. A mask 11 having an opening is provided in the vicinity of the rotary drum 3 so that the vapor deposition metal is not vapor deposited on the film 5 except at a predetermined angle. A shutter 13 is provided along the outer surface (or inner surface) of the mask 11, and it is slid in the direction of the arrow in the initial and final stages of vapor deposition to block the opening of the mask 11 to prevent unnecessary vapor deposition. Mask 11
The size of the opening is selected so that a predetermined vapor deposition width can be obtained on the film 5 in the axial direction of the rotary drum 3 and a predetermined vapor deposition angle θ can be obtained on the film in the circumferential direction of the rotary drum. . A gas supply nozzle 25 is arranged between the shutter 13 and the mask 11 to introduce a gas such as oxygen.

A crucible 15 made of high-purity magnesia (MgO) or the like is arranged facing the opening of the mask 11, and a raw material metal 17 to be vapor-deposited therein is charged therein. Crucible 1
Reference numeral 5 is elongated in the axial direction of the rotary drum 3 sufficiently to obtain a required vapor deposition width. The width W of the substrate film moving along the surface of the rotating drum preferably has the above-mentioned relation to the scanning length l of the electron beam scanning the crucible, so that the thickness of the deposited film can be changed to the substrate width. Can be constant in direction. The crucible 15 is arranged so as to obtain a predetermined vapor deposition angle θ (which slightly varies depending on the position in the opening of the mask). The raw metal 17 charged in the crucible 15 is heated by the electron beam 21 emitted from the electron gun 19. In the present invention, the electron beam 21 of the electron gun 19 is used.
The electron beam 21 is emitted in a direction forming an angle of about 90 degrees with respect to the line connecting the crucible 15 and the opening of the mask 11. This electron beam is bent by about 90 degrees by the action of a magnetic field 23 by an appropriate condenser lens, a converging lens, and a deflection coil (not shown), and at the same time, it is converged into a small spot and collides with the raw material metal 17. Experiments have shown that a significant increase in power can be achieved as compared to the conventional straight-ahead electron gun 19 'arranged at the chain line position in FIG.

Although the optimum angle of the minimum incident angle θ min differs depending on the use, especially Co or Co is used as a magnetic recording medium.
-If the Ni alloy is obliquely vapor-deposited on a base film such as polyester such as polyethylene terephthalate to make the easy magnetization direction oblique to the base, the minimum incident angle θmi
n is 10 ° to 60 °, preferably 20 ° to 50 °. Examples of the Co alloy include those described in Japanese Patent Publication No. 3-41897.

A specific operation example of the apparatus shown in FIG. 1 is as follows. The average minimum incident angle θ min is 30 degrees, and the average distance between the liquid surface of the crucible and the vapor deposition surface of the rotating drum 3 is about 300.
mm, the opening width of the mask is 500 mm, the vacuum chamber is evacuated to 1 × 10 ⁻⁵ Torr, and a polyethylene terephthalate film (PET) having a thickness of 7 μm is 100 to 2
Co-Ni alloy (80: 2) was run at 50 m / min.
The driving power of the electron gun 19 is 40 kV × (3 to 5 A) = 120 to 2 while intermittently supplying the pellet of 0) to the crucible 15.
It melts at 00 kW and vapor deposition is performed. Adjusting the film transport speed while keeping the electron gun power constant, the deposition film thickness is about 18
00 Å. In addition, the amount of the gas containing oxygen as the main component introduced into the gas supply nozzle 25 during vapor deposition is also appropriately adjusted to form a film so that equivalent magnetic characteristics can be obtained.

Next, the scanning method of the present invention will be described with reference to FIG. A shows the relationship between the X direction corresponding to the length of the crucible and the scanning speed distribution, A shows an appropriate speed distribution, and B shows an appropriate stepwise speed distribution of the present invention. The curve A can be easily derived from the temperature distribution when scanning at a constant speed in FIG. 3, or can be experimentally determined. Although it may be necessary to control in the Y direction as well, this may be performed by the conventional method described above. Since the curve A is flat in the center and steeper at both ends of the crucible, the stepwise polygonal line that approximates it can be approximated by B in the figure.

For example, the inner dimension of the crucible is 0.8 m ×
When the length was 0.08 m, a uniform temperature distribution could be obtained by allocating the scanning speed and the scanning length in the longitudinal direction as follows. Scan length (m) Scan speed (m / sec) 0.00 to 0.10 8.4 0.10 to 0.25 11.2 0.25 to 0.55 16.9 0.55 to 0.70 11 .2 0.70 to 0.80 8.4

Under this condition, the constant width was 0.60 m due to the dimensional relationship in the operation example described with reference to FIG.

[0019]

As described above, according to the present invention, the temperature of the crucible can be made uniform with the minimum control. Further, uniform vapor deposition can be easily achieved by making the length in the longitudinal direction sufficiently large.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a vapor deposition apparatus used in the present invention.

FIG. 2 is a diagram showing a conventional example of a crucible scanning method using an electron beam.

FIG. 3 is a diagram showing a temperature distribution in a crucible when an electron beam is scanned at a constant speed.

FIG. 4 is a partial cross-sectional plan view of the gas supply nozzle of the present invention.

[Explanation of symbols]

 1 Vapor Deposition Equipment 3 Rotating Drum 5 Base Film 7 Winding Roll 9 Feeding Roll 11 Mask 13 Shutter 15 Crucible 17 Raw Material 19 Electron Gun 21 Electron Beam 23 Deflection Magnetic Field 25 Gas Supply Nozzle 30 Crucible 32 Molten Metal

Front page continuation (72) Inventor Toshiyuki Otsuka 1-13-1, Nihonbashi, Chuo-ku, Tokyo Tea Decay Co., Ltd. (72) Shinji Miyazaki 1-13-1, Nihonbashi, Chuo-ku, Tokyo Tea Decay Co., Ltd.

Claims (3)

[Claims] 1. A rectangular crucible extending in the X direction or a raw material metal to be evaporated is accommodated, and an electron beam focused on the raw material metal is irradiated while repeatedly deflecting the electron beam in the X direction or the XY direction. In the melting method, the scanning speed in the X direction for scanning the electron beam is changed in several steps so that the scanning speed in the X direction is slower toward the end of the crucible and faster toward the center of the crucible. Metal melting method. 2. The scanning length of the stepwise scanning speed portion is shorter at the end of the crucible and longer at the center thereof.
Method for melting raw material metal in vacuum deposition. 3. The vacuum vapor deposition according to claim 1, wherein the electron beam scanning length in the X direction is 1, the width of the substrate is W, and 1 / W ≧ 1.3. Raw metal melting method. (Does this formula depend on the distance between the crucible and the substrate?)