JPS63183166A - Resistance heating boat for vapor deposition - Google Patents

Abstract

PURPOSE:To prevent direct arrival of bumping particles of a material for vapor deposition at a surface for vapor deposition by forming perforated cylindrical resistance heating element of a chimney type heating boat into double cylinders, covering the specific part thereof with heat resistant fibers and heating the innermost resistance heating elements to the max. temp. CONSTITUTION:The perforated cylindrical resistance heating elements 2, 2' are concentrically disposed in parallel in a cylindrical vessel 1. The inside of the heating element 2 and the outside of 2' are melted by heating and are covered with meshes 8 made of the heat resistant fibers. The material for vapor deposition is housed into a housing part 3 in the spacing between the inside wall of the vessel 1 and the heating element 2 and a voltage is impressed between the vessel 1 and the heating elements 2, 2' via conductors 4, 5. The heating elements 2, 2' and the meshed 8 are thereby made to generate heat quickly and the material for vapor deposition is heated to evaporate. The vapor thereof passes the through-holes of the elements 2, 2' and the meshes 8 and is released through the aperture 7 of a cap 6 to the outside. Splashing of the bumping particles of the material for vapor deposition is substantially prevented by the meshes 8 even if said material bumps and the bumping particles thereof partly pass the through-holes of the element 2. The particles collide against the meshes 8 of the element 2' even if said particles splash. The probability that the particles are released directly from the aperture 7 is therefore smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an improved resistance heated vapor deposition boat. More specifically, the present invention relates to a resistance heating boat for vapor deposition, which has a structure that prevents bumping particles of the vapor deposition material from directly reaching the surface to be vaporized during vacuum vapor deposition, and is capable of providing a defect-free protective film. It is something.

Conventional technology Conventionally, protective films such as silicon oxide have been used as protective films for magnetic heads and recording materials such as optical disks because of their good scratch resistance and shielding properties against moisture and oxidizing atmospheres. There is.

By the way, when using a sublimable substance such as silicon oxide as a material for vapor deposition and vaporizing and scattering it using a normal resistance heating method, bumping tends to occur during the operation, and the bumping particles tend to fly inside the vapor deposition apparatus, causing the vapor deposition to deteriorate. This often causes defects in the deposited film.

In order to prevent damage caused by such bumping particles,
A chimney-type heating boat with the structure shown in the figure has been proposed.

This is inside a cylindrical container 1 made of a heat-resistant conductive material.
A perforated cylindrical resistance heating element 2 having a large number of vapor permeation holes is arranged, a vapor deposition material is accommodated in the gap 3 between the inner wall of the cylindrical container 1 and the cylindrical resistance heating element 2, and a conducting wire 4 and 5, a voltage is applied between the inner wall of the cylindrical container and the cylindrical resistance heating element to heat the vaporization material, vaporize it, and scatter it through the opening 7 provided in the center of the lid 6. , and is released into the vapor deposition apparatus and attached to the surface to be vapor-deposited.

In this chimney-type heating boat, the upper part of the storage part 3 for the deposition material is isolated from the outside by a lid 6, and the evaporated particles of the deposition material are scattered to the outside through the permeation holes of the perforated cylindrical resistance heating element 2. Most of the bumping particles are absorbed by the lid 6.
It is prevented from being released directly to the outside. However, depending on the scattering direction of the bumping particles, the particles emitted from the permeation holes may be emitted directly to the outside from the opening 7 of the sand cover 6, or may repeatedly collide with the perforated cylindrical resistance heating element several times. After returning the particles, they may be released to the outside from the opening 7, and it is not always possible to completely prevent damage caused by bumping particles. Therefore, a protective layer that is extremely sensitive to film defects, such as the protection of recording materials for optical disks, is recommended. In the case of forming a layer, it is not yet fully satisfactory.

Problems to be Solved by the Invention An object of the present invention is to overcome the above-mentioned drawbacks of the conventional resistance heating boat for vapor deposition, and to prevent the bumping particles of the vapor deposition material from directly reaching the surface to be vapor-deposited, thereby making the boat free from defects. An object of the present invention is to provide an improved resistive heating system for vapor deposition that can provide a protective film.

Means for Solving the Problems The present inventors have discovered that in a conventional chimney-type heated boat,
As a result of intensive research on ways to minimize the release of bumping particles to the outside, we constructed the perforated cylindrical resistance heating element into a double cylinder.

A mesh or cotton-like material made of heat-resistant fibers is interposed at least on the outside, inside, or in the gaps between each part of the double cylinder, and the innermost part, that is, the farthest from the storage part of the material for vapor deposition, By keeping the heating temperature of the cylindrical resistance heating element at the highest position, the generated bumping particles are blocked by the mesh or cotton-like body, and clogging due to deposition of vaporized material vapor does not occur. The inventors have found a way to achieve this objective, and have developed the present invention based on this knowledge.

That is, in the present invention, a perforated cylindrical resistance heating element having a large number of vapor permeation holes is disposed inside a cylindrical container made of a heat-resistant conductive material, and the inner wall of the cylindrical container and the cylindrical resistance heating element A deposition material is stored in the gap between the containers, and a voltage is applied between the inner wall of the cylindrical container and the cylindrical resistance heating element to heat the deposition material and vaporize and scatter it. In a resistance heating boat, the perforated cylindrical resistance heating element is configured as a double tube, and a mesh or cotton-like material made of heat-resistant fiber is provided on the inside or outside of the double tube or at least in the gap between each part. The present invention provides a resistance heating boat for vapor deposition characterized in that the innermost cylindrical resistance heating element has the highest heating temperature.

Next, embodiments of the present invention will be described according to the accompanying drawings.

FIG. 2 is a cross-sectional explanatory view showing one example of the resistance heating boat for vapor deposition of the present invention, in which two perforated cylindrical resistance heating elements 2 and 2' are arranged concentrically inside the cylindrical container 1. A mesh 8 made of heat-resistant fibers that does not melt when heated is arranged in parallel, and on the inside of the perforated cylindrical resistance heating element 2 and the outside of 2'.
A storage portion 3 for the material for deposition is provided in the gap between the inner wall of the container and the perforated cylindrical resistance heating element on the side closer to the inner wall.
is formed. Cylindrical container 1 and resistance heating elements 2 and 2'
is connected to a power source via conductive wires 4 and 5, and when a voltage is applied between them, the resistance heating elements 2, 2' and the heat-resistant mesh 8 rapidly generate heat and are housed in the housing section 3. The vapor deposition material is heated, melted, and then vaporized. The lid 6 covers the housing part 3 and the upper part of the gap between the resistance heating elements 2 and 2'.
Only the portion surrounded by the resistance heating element 2' is the opening 7 of the lid 6.
It communicates with the outside world through.

Therefore, the vapor of the deposition material is transferred to the resistance heating elements 2 and 2.
' through the permeation hole and the mesh 8, and is discharged to the outside through the opening 7 of the lid 6.

When the vapor deposition material bumps, even if some of the bumping particles pass through the permeation holes of the resistance heating element 2, they are unlikely to scatter due to the mesh 8 provided inside thereof. Even if there are particles, these scattered particles will collide with the mesh 8 provided on the outside of the resistance heating element 2' placed further inside, so the probability that the particles will be emitted directly to the outside from the opening 7 of the lid 6 is low. becomes significantly smaller.

In this case, the two resistance heating elements 2, 2' are configured such that the one furthest from the vapor deposition material storage section 3, in other words, the one disposed at the innermost side of the container is heated to the highest temperature. It is necessary that the

In this way, the vapor of the vapor deposition material can be transferred to the resistance heating element 2'.
There is no risk of it becoming trapped and clogging.

Therefore, it is preferable to connect the power supply to the cylindrical container made of a heat-resistant conductive material and the resistance heating element 2' placed inside the container. As long as the condition of being heated to a higher temperature is met9
, the connection means may be in any manner.

The mesh made of heat-resistant fibers provided on the cylindrical resistance heating element 2.2' is made of metal fibers such as tungsten, tantalum, molybdenum, or ceramic fibers, and is used to enhance the effect of blocking bumping particles. To, 10
It is desirable that the mesh be as fine as possible, with a mesh number of 0 mesh (the number of meshes indicates the number of meshes within 1 inch) or more.

FIG. 3 is an explanatory cross-sectional view of another example of the resistance heating boat for vapor deposition according to the present invention. A structure in which a shaped body 8' is three-dimensionally embedded is shown.

In this way, in the gap between the concentrically arranged resistance heating elements,
By embedding a cotton-like body made of heat-resistant fibers, scattering of bumping particles to the outside can be more effectively prevented.

At this time, the cotton-like body made of heat-resistant image fibers used is as follows:
For example, a cotton-like body made of metal fibers such as tungsten, tantalum, or molybdenum or ceramic bifibers having a thickness of 100 μm or less, or a mesh made of the fibers multiplied to form a three-dimensional cotton-like body are preferably used. When multiplexing meshes, it is preferable to use 100 meshes or more as fine as possible.

In either case, to avoid clogging due to vapor traps, it is necessary that the resistive heating elements remote from the deposition material storage are heated to a higher temperature than those closer. .

Effects of the Invention In the resistance heating boat for vapor deposition of the present invention, the heating parts for heating and vaporizing the vapor deposition material are arranged concentrically in double rows so that only the vapor of the vapor deposition material can pass through. Because a fine mesh or cotton-like material made of heat-resistant fibers is arranged on at least one of the outside, the gap, and the inside of the hole-shaped resistance heating element, bumping particles of the deposition material rarely fly out to the outside. Since the resistance heating element placed inside has the highest temperature, the vapor of the deposition material will not be trapped, and the resistance heating element will not be clogged and the clogging area will not be trapped. The generation of bumping particles is also prevented, and as a result, an excellent coating without defects can be formed. Therefore, the heating boat of the present invention is particularly suitable for forming a protective layer of a recording material for optical dinuks.

Example Next, the present invention will be explained in more detail with reference to Examples.

Note that defects on the deposited film were evaluated as follows.

Semiconductor laser light with an oscillation wavelength of 830 nm was applied to a vapor deposition surface provided on a disk-shaped transparent substrate using an objective lens with a numerical aperture (N, A, ) of 0.5 to a beam diameter of approximately 1 μm under automatic focusing. Emits focused light. At this time, the irradiation intensity on the vapor deposition surface was set to about 1 mW, which does not cause any physical shape change such as crystallization or opening on the vapor deposition film.

The reflected light of the focused laser light is received by a photodiode, and changes in the intensity of the reflected light are electrically detected. If a defect exists on the film surface, it is detected as a pulse-like change in the intensity of reflected light.

The deposited film is provided on a 1.5 mm thick transparent acrylic substrate with a diameter of 305 mm and which has been thoroughly cleaned. The disk is rotated at 90.degree. rpm, and the number of racks equivalent to about 44,000 (approximately 44,000) racks in the range from the inner diameter of 140,111 .phi.

Defects were quantified as follows. As reflectance change, the average reflectance of the deposited film is t-100%, and a pulse exceeding ±10% is defined as a defect, and the pulse width is 160%.
n5ec f Standardized as 1 bit (for example,
When the pulse width is τn5ec, τ(160n5ec
o bits, t≦−<t+1 t pits). The error rate of the disc was quantified using the following formula.

n: Number of line defects tk i Number of pits of k-th defect Comparative Example A thoroughly cleaned 30φ diameter acrylic resin substrate was set in a vacuum deposition tank having two resistance heating deposition sources, and was used as a deposition surface.

A boat is set on one resistance heating evaporation source, Te is placed in the boat, a conventional chimney type heating boat 1f shown in Fig. 1 is set on the other resistance heating evaporation source, and S is placed in the boat.
i0 particles were added.

Next, the vacuum chamber was evacuated to f I
O40OA was deposited in this order. During vapor deposition, generation of S10 bumping particles was confirmed from the chimney-type heating boat.

When the deposited film thus formed was visually and microscopically observed, 20 pinholes on the order of several tens of micrometers were observed.

Three discs were manufactured in the same manner and the error rates were measured using a defect detection device, and the values shown in Table 1 were obtained.

Table 1 Example 1 The boat shown in FIG. 2 was set in place of the chimney-type heating boat in the comparative example, and SiO was set in a predetermined manner. The mesh 8 made of heat-resistant fiber shown in FIG.
A 100-mesh one made by W was used.

Three discs with the same configuration were created in exactly the same manner as in the comparative example. No pinholes were observed by naked eye or microscopic observation, and when the error rate (f) was measured using a defect measuring device, the values shown in Table 2 were obtained.

The error rate was significantly reduced compared to the comparative example in Table 2, confirming the effectiveness of the heating boat for vapor deposition of this structure.

Example 2 A boat shown in FIG. 3 was set in place of the chimney-type heating boat in the comparative example, and 810 was set in a predetermined manner. 8 made of heat-resistant fiber in Fig. 3 is 1 made of W.
It was made by stacking multiple 00 mesh nets and filling them into a three-dimensional cotton-like structure.

Three discs with the same configuration were created in exactly the same manner as in the comparative example. No pinholes were observed by naked eye or microscopic observation, and when the error rate was measured using a defect measuring device, the values shown in Table 3 were obtained.

The error rate was significantly reduced compared to the comparative example shown in Table 3, confirming the effectiveness of the heating boat for vapor deposition of this structure.

From the above examples, it can be seen that according to the heating boat of the present invention, it is possible to prevent the generation of bumping particles, and it is possible to form a deposited film with fewer defects.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional chimney-type heating boat, and FIGS. 2 and 3 are cross-sectional views of different examples of the resistance heating boat for vapor deposition of the present invention. container, 2,2
' is a perforated cylindrical resistance heating element, 3 is a vapor deposition material storage part, and 4.
5 is a conductive wire, 6 is a lid, 7 is an opening, 8 is a mesh made of heat-resistant fibers, and 8' is a cotton-like body made of heat-resistant fibers.

Claims (1)

[Claims] 1 A perforated cylindrical resistance heating element having a large number of vapor permeation holes is placed inside a cylindrical container made of a heat-resistant conductive material, and a perforated cylindrical resistance heating element is placed in the gap between the inner wall of the cylindrical container and the cylindrical resistance heating element. In a resistance heating boat for vapor deposition that houses a material for vapor deposition and applies a voltage between the inner wall of the cylindrical container and the cylindrical resistance heating element to heat the material for vapor deposition and vaporize and scatter it, Configuring the perforated cylindrical resistance heating element into a double cylinder, and interposing a mesh or cotton-like body made of heat-resistant fibers on the inside or outside of the double cylinder or at least in the gap between each cylinder, A resistance heating boat for deposition, characterized in that the innermost cylindrical resistance heating element has the highest heating temperature.