JPH0647016Y2 - Molecular beam source cell for low temperature vapor deposition - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved structure of a molecular beam source cell for vapor deposition at a relatively low temperature used in fields such as superconducting thin films and optical recording disks.

[0002]

Molecular beam source cells are used in molecular beam epitaxy, which is one of the crystal growth methods.
In the fields of superconducting thin films and optical recording disks, for example, second group metal elements such as Zn, Cd and Hg, S, Se,
A sixth group element such as Te or Po or an element having a relatively low melting point such as phthalocyanine is vacuum-deposited in a dilute oxygen gas atmosphere at a relatively low temperature of 100 to 500 ° C.

By the way, conventionally, as a general structure of such a molecular beam source cell, for example, JP-A-60-108400 is used.
Japanese Patent Application Laid-Open No. 1-141894, Japanese Patent Application Laid-Open No. 4-3
As is known in Japanese Patent Publication No. 9920 or Japanese Utility Model Publication No. 4-3005, a structure is adopted in which a heating unit enters a vacuum, and the material thereof is, for example, Ta, Mo,
A material such as PBN which releases a small amount of gas in a vacuum has been used.

[0004]

However, in the above-mentioned prior art molecular beam source cell, Ta which forms the heating portion,
Materials such as Mo and PBN are expensive and not suitable for use in vaporizing low melting point elements. This is M
Substances such as o and Ta easily react with other substances in a dilute oxygen gas atmosphere. For example, when a low melting point element such as a sulfur-selenium compound is handled in a vacuum chamber, its life shortens due to the reaction with it. Due to Therefore, there is a problem that it is difficult to increase the manufacturing cost of the cell and stably use the expensive heating part for a long period of time.

Therefore, the present invention solves the above problems in the prior art, that is, there is no reaction with the generated vapor gas in the dilute oxygen gas atmosphere in the vacuum chamber,
Therefore, it is an object of the present invention to provide an improved structure of a molecular beam source cell for low temperature vapor deposition, which has a long life, is easy to maintain, is easy to use, and can be manufactured at low cost.

[0006]

[Means for Solving the Problems] That is, according to the present invention, in order to achieve the above-mentioned object, a molecular beam source material which is arranged substantially in the center of a cell body and generates a molecular beam when heated is provided. A crucible housed in the recess, and a heater arranged on the outer periphery of the crucible, for heating and evaporating the molecular beam source material, and radiating the molecular beam into a vacuum atmosphere of a vacuum device. In the source cell, the crucible has a double-walled tubular structure made of glass, and the space surrounded by the inner wall is opened in the vacuum atmosphere of the vacuum device, and the inner wall and the outer wall are formed. A space formed between the inner wall and the outer wall of the heater is located in the space formed between the inner wall and the outer wall, and a double-walled glass double-walled tube forming the crucible. The end of the outer wall of the Low deposition molecular beam source cell is proposed which is characterized in that it air-tightly attached to the outer wall of the location.

[0007]

According to the molecular beam source cell for low temperature vapor deposition of the present invention described above, the heater is disposed in the space formed between the inner wall and the outer wall of the double-walled glass tube forming the crucible, Can be arranged outside the vacuum system (that is, on the atmosphere side). This makes it possible to prevent the heater from reacting with the vapor on the vacuum system side, prolongs the life of the heater, facilitates its maintenance, and is expensive, such as Ta, Mo, or PBN. It can be manufactured at low cost without using a different heater material.

[0008]

Embodiments of the present invention will be described in detail below with reference to the drawings. First, FIG. 1 shows a molecular beam source cell for low temperature vapor deposition, which is an embodiment of the present invention, together with its cross-sectional structure. ing. In this figure, the molecular beam source cell for low-temperature vapor deposition has a substantially disk-shaped metal mounting flange 20 for vacuuming an opening 11 formed in a part of an outer wall 10 of a vacuum chamber for bringing the inside into a high vacuum state. It is mounted so as to project into the atmosphere. Reference numeral 12 in the figure is a ring-shaped metal member inserted and fixed between the outer wall 10 of the vacuum chamber and the mounting flange 20, which is hermetically fixed by, for example, a through bolt.

The structure of the molecular beam source cell for low temperature vapor deposition is such that the second group metal element such as Zn, Cd and Hg and the sixth group such as S, Se, Te and Po are formed in the substantially center part of the cell body. An element or an element having a relatively low melting point such as phthalocyanine is housed in the recess and heated to 100 to 500 ° C.
That is, a crucible 22 that generates a molecular beam at a relatively low temperature is arranged. This crucible 22 is made of quartz glass, and its shape is a double-walled bag-like tubular structure, as shown clearly in the figure, and is a space surrounded by an inner wall 23. (That is, the crucible part)
Is on the vacuum atmosphere side in the vacuum chamber (upward in the figure)
On the other hand, the space formed between the double walls of the inner wall 23 and the outer wall 24 is opened, and the atmosphere side (lower side in the figure) is opened through the opening 21 formed in the center of the mounting flange 20. ) Is open to the public.

At the lower end of the crucible 22 made of quartz glass, an upper tip of a ring-shaped member 25 made of Kovar (alloy of Ni and Co) having a coefficient of thermal expansion similar to that of quartz glass is formed. Is hermetically connected by heating and melting, and the lower end of the Kovar steel ring-shaped member 25 is hermetically connected to the metal mounting flange 20 via a stainless-steel ring-shaped member 26.

A heater 30 is inserted through a circular opening 21 formed in the central portion of the mounting flange 20 and is arranged at a position surrounding the outer periphery of the crucible 22. That is, the heater 30 is inserted into a space opened between the inner wall 23 and the outer wall 24 of the crucible 22 having a double-walled tubular structure and opened to the atmosphere side, and the inner wall 23 of the crucible 22 is
The structure is such that the sample inside is heated from the outer circumference. In this embodiment, a sheathed heater 31 is used as the heater 30, and the sheathed heater 31 is wound around and mounted on the heater base 32. Two legs 33, 33 extend downward from the bottom of the heater base 32, and wirings 34, 34 for supplying heating power to the heater 30 are provided inside thereof. These wirings are connected to the DC power supply 35, for example, as illustrated.

Further, a recess 2 is formed in the center of the lower surface of the crucible 22.
21 is formed, and a thermocouple 40 for detecting the temperature in the crucible 22 is disposed in the recess along the leg portions 33, 33 of the heater from below. Reference numeral 4 in the figure
Reference numeral 1 denotes a member for fixing and holding the thermocouple 40 in the outer wall 24 forming the crucible 22. Reference numeral 42 pushes the thermocouple 40 upward, and its tip is a recess formed in the center of the lower surface of the crucible 22. 221 is a spring for pressing with a predetermined pressure, and reference numeral 45 is an electric circuit connected to the thermocouple 40. The electric circuit 45 is for detecting the temperature in the crucible 22 by electrical processing and performing necessary temperature control based on the detected temperature.

In the illustrated embodiment, the above crucible 2 is further added.
A cooling cylinder 50 is provided so as to surround the outer circumference of the cooling medium 2 to circulate a cooling medium inside for cooling and to control and adjust the temperature inside the crucible 22. As is clear from the drawing, the cooling cylinder 50 includes a cylindrical metal member 51 mounted on the mounting flange 20, a second cylindrical metal member 52 arranged on the upper outer periphery thereof, and upper and lower hollow discs. 5
3 and 54, inside of which, for example, liquefied nitrogen,
A coolant such as water is circulated and supplied. When a low temperature element having a relatively low melting point is used as the molecular beam source material, the molecular beam source material may melt and evaporate when baking the vacuum system. In order to prevent this, a refrigerant can be passed through the cooling cylinder 50 to perform vacuum-type baking while cooling the molecular beam source material.

Further, a shutter rod 55 is arranged outside the cylindrical metal member 51 constituting the cooling cylinder 50 so as to be rotatable in the direction of the arrow in the figure. A disc-shaped shutter 56 is attached to the tip of the shutter rod 55, and the shutter rod 5 is externally attached.
By rotating 5 the shutter 56 can be controlled to a position where it covers or opens the opening of the crucible 22. Further, the reference numeral 57 in the drawing is
A seal connecting mechanism for airtightly connecting the shutter rod 55 to the outside of the vacuum chamber.

In the molecular beam source cell for low temperature vapor deposition described above, the second group metal element such as Zn, Cd, and Hg, the sixth group element such as S, Se, Te, and Po, or the sixth group element in the crucible 22 is used. A molecular beam source material having a relatively low melting point such as phthalocyanine is housed and introduced into the vacuum chamber through an opening 11 formed in a part of the outer wall 10 of the vacuum chamber. Thereafter, heating power is applied to the heater 30 or the refrigerant in the cooling cylinder 50 is adjusted and controlled, and the low melting point element is heated at a relatively low temperature of about 100 to 500 ° C. to generate a molecular beam, and the shutter is released. Vacuum deposition is performed while opening and closing 56.

And, as is clear from the above structure,
In the low temperature vapor deposition molecular beam source cell of the present invention, the heater 30 for heating and evaporating the low melting point element for vapor deposition is formed between the inner wall 23 and the outer wall 24 of the double-walled glass double-walled tube forming the crucible 22. Since it is arranged in a space open to the atmosphere, it does not react with the vapor of the low melting point element generated in the vacuum chamber in a dilute oxygen atmosphere. Therefore, the heater 30 is reliably prevented from reacting with the generated steam to shorten the life of the heater, and the maintenance thereof is facilitated through the opening 21 formed in the central portion of the mounting flange 20 on the atmosphere side. Since it is removable,
It will be extremely easy. In addition, a cooling system can be passed through the cooling cylinder 50 to perform vacuum baking while cooling the molecular beam source material, which is particularly suitable as a low temperature vapor deposition molecular beam source cell. Further, it is not necessary to select and use an expensive heater material such as Ta, Mo, or PBN, which emits less gas in a vacuum, and other inexpensive materials can be selected. The whole cell can be manufactured at low cost.

[0017]

As is apparent from the above detailed description of the present invention, according to the molecular beam source cell for low temperature vapor deposition according to the present invention,
Since the heater can be configured not to be placed in the vacuum chamber but to be placed in the atmosphere, there is no reaction with the vapor gas in the lean atmosphere of the heater, thus prolonging the life of the heater, and The maintenance is easy and easy to use, and further, it is possible to obtain a low temperature vapor deposition molecular beam source cell that can be manufactured at low cost, which is a very excellent practical effect.

[Brief description of drawings]

FIG. 1 is an overall perspective view including a cross-section for explaining details of an internal structure of a low temperature vapor deposition molecular beam source cell according to an embodiment of the present invention.

[Explanation of symbols]

 10 Outer wall of vacuum chamber 11 Opening 20 Mounting flange 21 Opening 22 Crucible 23 Crucible inner wall 24 Crucible outer wall 25 Kovar steel ring-shaped member 26 Stainless ring-shaped member 30 Heater 35 Power supply for heating power 40 Thermocouple 50 Cooling tube 56 Shutter

Claims (2)

[Reference Number] 09200997-02 [Claims for utility model registration] 1. A crucible, which is arranged substantially in the center of the cell body and accommodates a molecular beam source material that generates a molecular beam when heated, in a recess thereof, and a heater arranged on the outer periphery of the crucible. In a molecular beam source cell for low-temperature vapor deposition, which comprises heating and evaporating a molecular beam source material to radiate a molecular beam into a vacuum atmosphere of a vacuum apparatus, the crucible is a double-walled bag-shaped tubular structure formed of glass. The space formed by the inner wall is opened to the vacuum atmosphere of the vacuum device, the space formed between the inner wall and the outer wall is opened to the atmosphere side, and the heater is The end portion of the outer wall of the glass double-walled bag tube that is arranged in the space formed between the inner wall and the outer wall and that forms the crucible is airtightly attached to the outer wall of the vacuum device. Molecules for low temperature vapor deposition characterized by Source cell. 2. The apparatus according to claim 1, wherein an end portion of the outer wall of the glass double-walled tube is hermetically attached to the outer wall of the vacuum device via a ring-shaped member made of Kovar steel. Molecular beam source cell for low temperature vapor deposition.