GB2175015A

GB2175015A - Depositing vaporized material uniformly

Info

Publication number: GB2175015A
Application number: GB08607873A
Authority: GB
Inventors: Masashi Kamio; Yoshitaka Enami
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1985-03-29
Filing date: 1986-04-01
Publication date: 1986-11-19
Also published as: DE3605486A1; GB8607873D0; JPS61227165A

Abstract

Substrates (25) as illustrated in Figs. 3 and 5 are rotated about respective axes which are positioned a fixed distance away from a center axis, which corresponds to an emission point (12) for the vaporized material, which is ionized so that it stays in contact with the substrates after collision. Because the substrates (25) are rotated, the vaporized material is deposited with a uniform thickness on the substrates. <IMAGE>

Description

SPECIFICATION Vaporizing apparatus and method employing same The present invention relates to an evaporating or vaporizing apparatus in which deposition of vaporized matter can be carried out uniformly.

Fig. 3 is a conventional vaporizing apparatus as disclosed in Japanese Patent Unexamined Publication No. 54-9592. In the Figure, the reference numeral 1 designates a vacuum tank connected with an upper base 2 and a lower base 3 at its upper and lower portions respectively, the vacuum tank 1 having an exhaust port 4 projecting from the lower base 3. Within the vacuum tank 1 there are, among other components, a furnace 5 for vaporizing material, an ion drawing electrode 6, a furnace support 7, an ion drawing electrode support 8, an electron emitting filament 10, a furnace heater 15, and a substrate mount 18.

In the outside of the vacuum tank 1 there are arranged a D.C. high voltage power supply 9, an electron emitting filament heater power supply 13, and a furnace heater power supply 16.

The reference numeral 11 designates an electron beam, 12 a small hole for emitting vaporized material, 14 material which is to be ionized for deposition, 17 vaporized material, 19 a substrate onto which the vaporized material is to be deposited, and 20 an ionized cluster beam.

The operation of this device is as follows: The material 14 is put in the furnace 5, and the heater 15 is energized by the power supply 16 to melt the material, in order to generate the vaporized material 17. As a result, the pressure within the furnace 5 rises, and the vaporized material 17 is ejected upwardly from the small hole 12. The ejected vaporized material 17 collides with the electron beam 11 when it passes by the electron emitting filament 10, so that the electrons of the atoms of the vapor are blown off, whereby the vaporized material becomes ionized. The ionized cluster beam 20 is accelerated by the voltage supplied between the ion drawing electrode 5 and the substrate mount 18 by the power supply 9. The accelerated cluster beam 20 collides with the substrate 19 and then migrates on the surface of the substrate 19.Because of the migration effect, a film of evaporated material is formed on the substrate 19. During the above operation, vacuum is maintained in the vacuum tank 1 by a vacuum pump connected with the exhaust port 4.

As described above, the conventional evaporating apparatus is disadvantageous in that more evaporated material is deposited in the center portion of the substrate than in a peripheral portion thereof, as shown in Fig. 4, so that it is difficult to form a film of substantially uniform thickness.

The present invention eliminates the above-discussed disadvantage. Accordingly, an object of the invention is to provide an evaporating apparatus in which a film of evaporated material deposited on a substrate has a uniform thickness.

The vaporizing apparatus according to the invention is provided with a supporting frame for arranging a plurality of substrates at a predetermined distance from a center line of a small hole of a crucible, the supporting frame being arranged to be rotatable, so that evaporated material is deposited onto substrates which are being rotated. Because the substrates rotate, deposition of vaporized material is uniform.

In the accompanying drawings Figure 1 is a plan view of an evaporating apparatus according to an embodiment of the present invention; Figure 2 is a bottom view showing the arrangement of the substrates of Fig. 1; Figure 3 is a plan view showing a conventional evaporating apparatus; Figure 4 is a graph showing the distribution of thickness of material deposited onto a substrate by a conventional vaporizing apparatus; Figure 5 is a view showing the gear arrangement of Fig. 1; and Figures 6(aJ-6(c) are graphs showing the distribution of thickness of vaporized material deposited onto the substrates shown in Fig. 1.

Referring to the drawings, an embodiment of the present invention now will be described. The reference numerals 1-17 and 20 in Fig. 1 designate the same parts as those in the conventional vaporizing apparatus. The reference numeral 21 designates a supporting frame mounted on the upper base 2, 22 a plurality of substrate mounts rotatably supported by the supporting frame 21 and each separated from a center axis of the crucible 5 by a predetermined distance, 23 a gear arrangement connected with the substrate mounts 22, and 24 a drive unit connected with the gear arrangement 23. In the vaporizing apparatus thus arranged, each of the substrate mounts 22 is individually rotated in a predetermined direction by the drive unit 24.

Fig. 5 shows the structure of the gear arrangement 23. The reference numeral 27 designates a rotary shaft of the drive unit 24. A main gear 26 is mounted on a rotary shaft 27 of the drive unit 24. Subsidiary gears 20 engage the main gear 26. The substrate mounts 22 are mounted on corresponding subsidiary gears.

Fig. 2 shows the arrangement of the substrate mounts 22 which are respectively connected to the corresponding rotary shafts 29 of the subsidiary gears 28 so as to rotate together with the subsidiary gears, and which are supported by the supporting frame 21.

In the vaporizing apparatus thus arranged, the respective substrate mounts 22 are rotated in the same direction, for example, clockwise, at a constant speed, by the drive unit 24. The substrates 25 are respectively mounted onto the corresponding substrate mounts 22, and then the drive unit 24 is started so as to perform vaporization.

In this case, if evaporation is performed without rotating the substrates, the film thickness has the distribution shown in Fig. 6(a), and accordingly, the distribution of the film thickness on the substrate mounts 22 disposed on the supporting frame at a certain distance from the center line of the small hole of the support frame 21 is such that the film thickness decreases as the distance from the center line of the small hole 21 increases, as shown in Fig. 6(b).

If the substrate drive unit 24 is started for performing rotational evaporation, the distance from the center line of the small hole on the supporting frame 21 to the rotational axis thereof does not change. However, because of the rotation of the substrate mounts 22, the distance from the center line to other points on the individual substrates can change. Uniform collision of the evaporated matter against the substrates results, so that the layer of vaporized material on each of the substrates 25 is made substantially uniform, as shown in Fig. 6(c).

In the vaporizing apparatus as described above, the substrates 25 are respectively mounted on the corresponding substrate mounts 22 and then the drive unit 24 is started to perform vaporization. In this case, the substrates 25 are rotated around the corresponding axes each separated by a predetermined distance from the center axis of the crucible 5, so that the layer of the matter evaporated onto the substrates 25 can be made substantially uniform.

Although the above embodiment shows the case where a plurality of substrate mounts are rotated by a single drive unit, the invention is also applicable to the case where a plurality of substrate mounts are rotated independently of one another, with the same effect.

As described above, according to the invention, the thickness of the films of vaporized material on the respective substrates can be made uniform, since the supporting frame for arranging the plurality of substrates to be deposited with the evaporation film separately from the center line of the small hole of the crucible by a pre-determined distance can be rotated about the center line of the small hole.

Claims

1. A vaporizing apparatus for depositing vaporized material onto a substrate, said apparatus comprising a crucible used in melting the material and having a small hole for emitting vaporized material, said small hole having a first center line passing therethrough, means for ionizing the vaporized material, including means for causing said ionized material to collide with said substrate and be deposited onto said substrate; and substrate turning means for rotating said substrate about a second center line substantially parallel to said first center line and separated from said first center line by a predetermined distance, a radius of said substrate being less than the distance between said first and second center lines.

2. A vaporizing apparatus according to Claim 1, comprising a plurality of substrates and a plurality of said substrate turning means for rotating respective ones of said substrates about different respective center lines corresponding to said second center line.

3. A vaporizing apparatus according to Claim 1, wherein said substrate turning means comprises a main gear having said first center line pass through its center, and at least one subsidiary gear positioned around an outer periphery of said main gear, rotation of said main gear turning said subsidiary gear to thereby turn said substrate.

4. A vaporizing apparatus according to Claim 1 comprising a plurality of independentlyrotating substrate turning means for rotating said substrates independently of each other.

5. In a method of depositing vaporized material onto substrates, said method comprising the steps of passing vaporized material through a hole which is substantially aligned with a first center line, ionizing the vaporized material, and causing said ionized material to collide with a substrate, whereby the material to collide with a substrate, whereby the material is deposited onto the substrate; the improvement wherein said substrate is rotated about a second center line substantially parallel to said first center line and positioned a predetermined distance from said first center line, whereby said vaporized material is deposited uniformly on said substrate.

6. A method according to Claim 5, wherein said step of causing said vaporized material to collide with said substrate comprises the step of causing said vaporized material to collide with a plurality of substrates, each of said substrates rotating about respective substantially parallel center lines which in turn are parallel to said first center line, and are positioned said predetermined distance therefrom.

7. A method according to Claim 6, wherein said substrates rotate independently from each other.

8. A method according to Claim 6, wherein said substrates are rotated substantially in synchronization with each other.