JPH0483867A - Formation of thin film on thin strip by electron beam flash deposition - Google Patents

Abstract

PURPOSE:To continuously mass-produce a vapor-deposited thin film uniform in composition at a high rate by using an electron beam as a heat source, passing a thin strip of the same composition as the desired thin film and having a large width (>=1 m) above a water-cooled crucible (hearth), continuously supplying the strip and using the strip as the target for the flash vaporization by the electron beam. CONSTITUTION:A thin strip 1 is horizontally (orthogonal to the deflected beam surface) traveled above a hearth 3 in the(y) direction, a beam 2 is vertically injected into the strip 1 close to the center axis of the cup of the hearth 3, and flash vaporization is carried out. At this time, the lower surface of a deck 4 is planed (strip width X depth = about 1mm), the strip 1 is passed through the gap 5 formed between the deck 4 and hearth 3, and a hearth protective disk 7 is firmly held to the hearth bottom, as required. A strip supply drum 9 and a strip winder 10 are furnished respectively on both sides of the hearth 3, driven and controlled, and the traveling speed is adjusted so that the strip 1 is horizontally spread and the flash efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION INDUSTRIAL APPLICATION J This invention relates to a method for manufacturing thin films of electronic materials such as soft magnetism, hard magnetism, superconductivity, semiconductors and dielectric materials.

"Prior art and its problems - 1 In thin films of electronic materials, there are often significant differences in vapor pressure between the constituent elements.

In this case, in the sputtering film forming method, there is relatively little compositional deviation between the evaporation source and the film, but the film forming rate is slow.

However, in the electron beam evaporation method, the film formation rate is high (L), but the composition deviation is large. This is because fractionation occurs in the melt pool formed in the hearth due to beam heating. One solution to this problem is simultaneous evaporation from evaporation sources for each element, but control is complicated and the composition changes depending on the position on the substrate side. After all, one alloy composition evaporation source is desirable).

There is a flash method as a method to eliminate this difference in fractional composition. In this method, a linear or granular evaporation source is supplied onto a high-temperature resistance heating element at a supply rate that does not leave a molten pool, and the supplied material evaporates almost instantly and is deposited with its entire composition intact. It is something. This flash method has hardly been applied to a completely different type of electron beam evaporation method. This is because it is difficult to supply a particle or linear evaporation source so that it hits the electron beam incident vertically downward, and to apply beam energy directly to the evaporation source to stably and continuously evaporate the flanite.

The purpose of this invention is to take advantage of the advantages of electron beam evaporation, which can be applied to high-melting-point materials at high film formation speed and without contamination, and to achieve evaporation that utilizes a continuous flash method without compositional deviation. By devising the form of the source and its supply method, the aim is to produce a deposited film with a composition containing components with significantly different vapor pressures.

"Means and actions to solve the problem" The conditions for flash evaporation of the beam irradiated area are that the heat capacity of that area is small and the heat transfer to the non-irradiated (low temperature) area is zero or small. . The grains meet these requirements, but the supply method is difficult.

(1) Therefore, in configuration (+) of the present invention, a ribbon, particularly a liquid quenched ribbon, is used as the evaporation source as one that satisfies both of these conditions. Fortunately, in recent years, technology for producing quenched ribbons from liquids has progressed, and especially for soft magnetic amorphous ribbons, thicknesses of 15 to 1
Drum-wound elongated thin ribbons with a width of several centimeters or more are manufactured at 0.00 micron. The technology for producing wide ribbons, not only amorphous but also crystalline, has now been established, and ribbons of various compositions can be produced using this method. However, since it is used for electron beam evaporation, it should be made by a single roll method in vacuum or inert gas with a low gas content.

For more information, see Water Volume Edit [Guidebook for Creating Amorphous Alloys]
(1986 Agne Technology Center) I would like to see it.

Since the liquid quenched ribbon is used, the following effects can be obtained.

(1-a) A large number of functional electronic materials can be flash evaporation sources (targets) in the form of quenched ribbons.

(1-b) Since it can be made very thin, it has a small heat capacity and solid heat transfer loss, making flash evaporation possible.

(]-c) It is not only thin but also flexible, so it can be wrapped around a drum. This enables continuous mass production by placing a large amount of evaporation sources in a vacuum chamber.

(+-d) Since a wide ribbon is targeted, the central part can be evaporated by the beam flash, leaving both edges. Therefore, it is possible to drive and control not only the feeding side of the ribbon but also the winding side, so that the ribbon can be stretched horizontally so that the beam is perpendicularly incident, and continuous feeding control at an optimum speed is possible.

In addition to this quenched ribbon, the following two can also be used as thin ribbons. (1) Depending on the composition, some products can be rolled into thin strips, which can also be used.

” This is more advantageous from the point of view of productivity. However, sufficient cleaning and preliminary gas release are required. (ii) If the desired film composition except for a certain component tends to form a liquid quenched ribbon or a rolled ribbon, first prepare these ribbons and remove the component on one or both sides. The components are evaporated, sputtered or (2) continuously flashed by incorporating these ribbons (A-C), and then the process configuration is described (2-D-E).

(2-A) The ribbon runs above the hearth in the y direction (perpendicular to the deflected beam plane) while keeping it horizontal. The beam is perpendicularly incident on the ribbon near the central axis of the Haas cup, and flash evaporation is performed. For equipment with a hearth deck, adjust the bottom surface of the deck to match the ribbon running position (width of the ribbon x approximately 1 depth).
Plane with mm).

Pass the thin strip through this gap between the deck and the hearth. (
2-B) If necessary, place a disc to protect the hearth in close contact with the bottom of the hearth. This is because when absorbing the heat of the beam passing through the flash hole and discharging it by water cooling, there is a risk of damage if the beam is directly received by the hearth. This should be a thick material with good conductivity and a high melting point so that further evaporation is negligible compared to flash evaporation from the ribbon. If a thick disk with the same composition as the thin strip is used, even if a small amount evaporates, it will have little effect on the composition of the deposited film. A normal hearth can also be used to dissipate beam heat through this disc, but a large recess is not necessarily required for this purpose (a hearth-like structure may be sufficient).

(2-C) #The fabric supply side drum device and the winding device are installed on both sides of the hearth. By driving and controlling these, W
To enable an i-band to be stretched horizontally and to adjust the traveling speed to a high flash efficiency.

(Good efficiency means increasing the ratio of the beam energy used to evaporate the ribbon and the beam energy used to pass through the flash hole.) (2-D) Tight beam diameter Δy (cm) of electronic heater J1
From the sweep width △x (cm), which is narrower than the ribbon width, the flannel irradiation area △x If the size and specific gravity are known, the time required for flushing △ can be calculated as −ΔH2′+8. The formula is: S irradiation area, thickness x specific gravity/beam output. From this ΔL and 4y, can we determine the traveling speed at maximum efficiency V = Oy/Ot (mainly due to radiation)?
The actual speed will be smaller than this because of heat radiation loss and beam loss when drilling holes. The actual optimum speed is determined by trial. Note that the above X sweep has a high speed (500
Hz) using a high voltage sweep.

(2-E) There is also a method of applying beam current intermittently. That is, the beam current is set to zero immediately after flash evaporation of the irradiation part, and this beam current is turned on and off repeatedly at an appropriate duty ratio (ratio of the time width of TL flow ion off). In this case, the speed will be slower due to the duty ratio compared to (2-D), but the average radiant heat radiation from the irradiated part of the beam will also be generated, and the thermal influence on the substrate can be reduced. Since the distance between the evaporation section and the substrate can be brought closer, the evaporation yield can be improved.

In some cases, instead of feeding the ribbon at a continuous speed V, it is also possible to feed the ribbon piece by piece. That is, the stationary ribbon is irradiated with a flash beam for a necessary short time, the frame is advanced with a little margin corresponding to the missed beam hole (Δx×Δy), and this flash and frame advance are repeated one after another.

With the configurations (1) and (2) above, it is possible to efficiently mass-produce electron beam flash vapor deposited films without compositional deviations continuously and at a high deposition rate.

``Example'' 1. It is known that the soft magnetic alloy sendust can be formed into a crystalline quenched ribbon. The enthalpy of evaporation is ΔH of pure iron.
Bg, r-7, 6K approximated as the same as J/E,
Ribbon thickness 20 microns, specific gravity 8, output of electron beam used 10 kilowatts, irradiation area 4ykAX = 0.5cv
Assuming X3cm, calculating (2-D), the time required for flashing assuming no loss is At-~0.0
2 seconds can be changed. If the actual Δ1 is estimated to be about 0.05 sec, then the ribbon running speed at maximum efficiency V-Δy/t=o, 510°05=lOcm/sec can be obtained. This is 0*8g/se
It corresponds to the evaporation rate of c. Sendust vapor deposited film is e
ooc.

Shows good soft magnetism after 1 hour of heat treatment. Regarding heat treatment, etc., refer to literature (classic book, Journal of the Applied Magnetics Society, 12゜597.19
88).

2. An example of a material that becomes an amorphous ribbon by the liquid quenching method and becomes microcrystalline by subsequent heat treatment and exhibits soft magnetism with good thermal stability: Fey, g Cu 7 N b3S i
13. There is r89 alloy (trade name Finemet),
As a thin strip, it is expected to be applied to switching power supplies and sensors. Using this amorphous thin strip (thickness 20 microns, width 5 cm) as a flash evaporation source, and heat-treating the deposited film at 5500°C, it becomes a microcrystalline thin film with high saturation magnetic flux density and high magnetic permeability. It can be flattened for use in magnetic heads or laminated magnetic heads.

Regarding Finemet, please refer to the literature (Yamauchi, Yoshi R: Applied F!i Ki Gakkai Journal, 13, 231.1989).

3. Another example of a microcrystalline soft magnetic material with high saturation magnetic flux density and high magnetic permeability is "79" with a composition near FeTaC.
10N alloy, which is made into a thin film by sputtering. The Ta film thickness is adjusted to achieve this. The thin ribbon can be flashed to form a thin film, and it can be heat-treated for microcrystallization (approximately 580°C) to exhibit good soft magnetism.

2, it can be used for a magnetic head. Furthermore, Fe
Regarding the heat treatment and soft magnetism of TaC films, see the literature (for Hase,
Saito, Applied Magnetics Society Lecture Abstracts 25aD2. +989)
Please refer to

That's all. In Section 2.3, soft magnetic thin film manufacturing methods using crystalline, amorphous, and composite ribbons as evaporation source ribbons were explained as examples. This manufacturing method can also be used for thin films of electronic materials in other fields (hard magnetism, superconductivity, semiconductors, dielectrics, etc.) if the materials can be made into ribbons or composite ribbons. It is possible. Furthermore, if the transverse type in the above example is changed to a large-scale self-acceleration type electron beam device, it is possible to deposit a thicker thin strip at a higher speed, and if an ion blating type deposition method is adopted, the film quality can be improved. It is also possible to measure.

``Effects of the Invention'' As explained above, this invention can produce thin films deposited continuously and at a high deposition rate without compositional deviation, so in the case of soft magnetism as an example, thin films of several to tens of microns can be deposited. This greatly contributes to improving the productivity of thin film heads, MIG heads, and laminated heads that require. Similarly, in the mass production of composition-sensitive functional films in other electronic fields, the present invention, that is, the film forming method using electron beam flash evaporation of a thin ribbon having the same composition, becomes one of the effective means.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view in the xz plane including the central axis of the vapor deposited film manufacturing apparatus of the present invention, and Fig. 2 is a perspective view of the apparatus showing the feeding status of the ribbon (excluding the /%-striped part). (It is a drawing)
, Figure 3 shows the rows of holes in the flanges of the thin strip that passes through the beam irradiation section. 3 is an engraving of the continuous irradiation drawing (Drawing with no additional details) 1: thin strip, 2: N beam, 3: hearth, 4: hearth deck, 5: thin strip passage between hearth and deck, 6゛ flat hole passage Without beam, 7:71-Shosai'L figure

Claims (1)

[Claims] 1. In the flash deposition thin film manufacturing method, the heating source is an electron beam, and a wide (1 cm) beam having the same composition as the target thin film is used.
A thin strip of diameter (more than m) is continuously fed by passing it over a water-cooled crucible (hearth) or a hearth-like structure (for heat absorption and water-cooled exhaust heat of the beam passing through the flash hole), and the thin strip is used for flash evaporation of the electron beam. A method for producing a vapor-deposited thin film characterized by targeting. 2. 2. The thin film manufacturing method according to claim 1, wherein the ribbon is a liquid quenched ribbon. 3. 2. The thin film manufacturing method according to claim 1, wherein the ribbon is a rolled ribbon. 3. A composite multilayer ribbon in which one or several main components are the ribbons in the second or third term above, and the remaining one or several components are laminated on one or both sides of the ribbon. The thin film manufacturing method according to claim 1, wherein the thin film is a thin ribbon.