JPH04500241A - Method and apparatus for depositing coatings on supports in vacuum - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] A method and apparatus for depositing a coating on a support in a vacuum is disclosed. In order to deposit gold coatings, the method involves heating at least one coating material. The vapor obtained by condensing onto the surface of the support to be coated (before consisting of guiding between hot walls, the walls being at least approximately constant over the guiding length. It forms a flow cross section. Furthermore, the present invention provides an apparatus (C related.

For example, when providing an epitaxial layer on a support in the production of semiconductor devices, the material In order to satisfy the high quality requirements ('c is epitaxial Ht IK ? grown on the support from the vapor phase in the medium. For this purpose evaporate the coating material Evaporate it indoors, and pass the vapor into the vacuum chamber through an opening with a relatively small cross section. It is known that the substrate to be coated in the vacuum chamber is exposed to the evaporation chamber. Since the metal is held at a predetermined distance from the support, vapor escaping onto the support will be absorbed by the support to be coated. The growth rate depends on the support surface'\, temperature conditions, and the steam temperature and support temperature. The growth rate is adjustable through condensation. The outlet opening of the evaporation chamber allows the steam to flow out. Forms a flow restriction aperture that directs the vapor flow toward the support. Can be done. VB degrees of steam in the steam stream leaving the steam chamber, over the flow cross-section Since a uniform distribution of the fusuma cannot be obtained, is there a uniform thickness of the fusuma? To obtain, the coating-r should be the support surface. It must be chosen to be significantly smaller than the flow cross-section of the vapor stream in the area of the entire surface support. This is an epitaxial The formation of membranes also requires too high a material consumption.

In order to reduce the use of bright materials compared to the volume of the film, the amount of material flowing out of the evaporation chamber is It is known that the vapor of the coating material used in the coating is guided in a tube heated by the jaws, and the The side receives the substrate to be coated. In this way, steam profit guides between hot walls The thing is (because of the relatively high wall temperature, steam does not contract at the wall) , between the evaporation chamber and the support 1 a small (and almost closed) vapor guide is obtained. This limits material consumption, but also prevents the vapor density from becoming non-uniform across the flow cross-section of the tube. Because of the distribution, it is possible to uniformly cover a relatively large support surface unless complicated measures are taken. I can't do that. On top of that, the support is epitomized in an undesirable manner by the adjacent hot wall 1. There is a danger that it will be heated to a temperature that exceeds the surface temperature that is favorable for the growth of taxial growth.

The object of the invention is therefore to avoid the above-mentioned disadvantages and to provide a relatively large support surface. is coated uniformly with at least one evaporated coating material with advantageous material utilization. The objective is to provide a method that guarantees that

The means of the invention for solving the above-mentioned problem arise from a method of the type mentioned at the outset. The steam is first passed through before leaving and exiting between the hot walls under a free-flowing state of molecules. between hot walls over a length equal to or more than 1'V2 times the minimum diameter of the cross section. From the minimum diameter of the flow cross section formed by the guiding and hot wall on the exit side 2 Condensation onto the surface of the support to be coated after passing the entire average flow distance equal to V2 times It is composed of things.

The minimum diameter of the flow cross-section formed by this wall is Carefully guiding the length to a length equivalent to at least 1V2 times requires the freedom of molecules. It is possible to parallelize the flow of molecules to some extent if the motion information is taken into account. This is because in this case, in particular, at least the flow axis defined by the hot wall Only vapor molecules moving in the direction of can exit the channel formed by the hot wall. This is because it can be done. This collimation effect is impaired by collisions of relatively large numbers of molecular particles. In order to avoid this, a state of free flow of molecules must be maintained. Therefore this For flow conditions such as , the average free path length of the vapor molecules or atoms of the coating material must correspond to at least the minimum diameter of the flow cross section. No. When using multiple cladding materials, this condition determines the minimum mean free path length. This applies to coating materials that have The mean free path length of the molecular particles of steam changes significantly with the steam temperature. The required free flowing state of the molecules also depends on the appropriate temperature control in a simple manner. can be maintained through.

However, the hot steam between the walls passes through a certain flow distance, not immediately after it leaves. It is then allowed to condense onto the substrate surface to be coated. i.e. hot wall outflow end The distribution of density in the far field within a certain distance range A uniform density S is obtained over a relatively large flow cross section within the field. Therefore, within the range of the near field, even relatively large support surfaces can be epitaxially The taxial film can be uniformly provided. W at the outflow end of the hot wall! in the surroundings This effect is advantageous within a distance range of 21/2 times from the minimum diameter of the flow cross section. The density of molecular particles increases as the distance from the flow axis increases. The uniform density distribution is followed by a sudden drop, and the material loss caused by this should be avoided. loss is limited to a limited extent and - requires excellent coverage and good material utilization. can be advantageously linked.

In the configuration of the invention, particularly advantageous growth conditions for the epitaxial film are The air formed by the hot wall on the exit side before condensing onto the support surface to be coated Flow freely through an average flow path @ corresponding to 1 to 11/2 times the minimum diameter of the flow cross section. This distance relationship guarantees that the This ensures optimization with respect to uniform growth of the film and with regard to material utilization. Ru.

In order to carry out the method according to the invention, it is necessary to provide at least 1'C of evaporation chamber in the Makabe chamber. Both one and i″L7′C, placed in the axial direction of the channel, for the supporting book to be covered. holder and a total of 1 □, wherein said evaporation chamber has at least a substantially constant flow rate. Climb the mountain from a type that has a cross-sectional metal and has a complete flow path that can be heated immediately and communicates between walls. . This outfit! ! l is the length of the flow path O between the FI heatable walls that is at least the minimum diameter of the flow path. is also equivalent to 1V'2 times, and the holder is set according to the position of the support. The distance from the end is the outlet cross section of the flow path. The vacuum chamber is configured so that the amount is 217/'2 times the amount S be done. Heatable wall-mount fluid pipe 5 (should be properly set up and covered with Ffi+) 7 points of the support 7T ＋・S (within the range of the second support, and between the hot walls ψ the exit of the hermitage) A uniform density distribution over the cross section of the aperture (which corresponds to the cross section) Flow] 1 is necessarily achieved with 1.-1. In addition, the distance between the support to be covered and the outlet end of the channel is determined by the width of the outlet cross section of the channel. This is especially true when the diameter is 1 to 11z'2 times the diameter.

In this regard, it should be mentioned that the flow path [generally has a circular cross section]. I have to go. However, the hot wall can correspondingly be formed by an S-tube. Ru.

However, for supports with a contour shape different from a circular cross section, other A cross-sectional shape adapted to the contour shape of can also be arranged with respect to the flow path, and There is no need for the flow path to be formed in a closed manner by hot walls.

It is necessary to guide the steam flow thoroughly between the hot walls.

The method according to the invention will be explained in detail on the basis of the drawings.

The drawing shows an apparatus according to the invention for depositing a film on a support in vacuum with axis 1 It is shown in a schematic cross-sectional view including:

The device according to the illustrated embodiment is shown only schematically by a dotted line. lE vacancy 1 The vacuum chamber has a residual Goss Et of up to 101 mbar. should be covered The support can be provided with an epitaxial film consisting of a coating material with a number of 6 Kff. Concentric evaporation chambers 2, 3.4 are arranged within a quartz tube 5 within a vacuum chamber 1. steaming Release room 2, 3. , a heater 7.8°9 is assigned to these for 7ID heat of 4. The heaters each have a corresponding connecting ring distributed around the quartz tube 5. 11 is provided with an electrical resistance heating conductor 10 between them. These heaters γ.

8.91 is shielded from the outside by a plurality of molybdenum shields 12, and The budene shield encloses the resistive heating conductor 10.

The evaporation chambers 2, 3.4 communicate with a pipe 13, which has an evaporation chamber 2 completely formed in the region of its lower end. and the tube wall 14 can be similarly heated via the heating device 2t. Wear. The heating device is a resistive heating device arranged between the connecting rings 11 in a comparable form and manner. It is composed of a thermal conductor 10. This tube 13 has hot walls 14 and is connected to the evaporation chambers 2, 3. A flow path 161i- is formed for the steam obtained from .degree.4.

After the steam exits into the vacuum chamber 1 from the outlet end 17 of the tube 13 and follows a free flow path, The electrical power is distributed within the holder 18 at a distance from the outlet end 17 at a distance from the outlet end 17. condenses on the surface. The growth rate of epitaxial films depends on the vapor pressure and and the temperature of the support 64, and a heater 19 is assigned to the support through the hole. has been done.

Between the outlet end 11 of the tube 13 and the holder 18 for the support 6 there is a A rotatably adjustable and movable shutter 21 is provided, and the coating process is controlled through the shutter. You can define the exact start and end.

According to the exemplary embodiment, the support 6 consists of a disk of arsenide with a diameter of 25 cm. this If arsenide is placed on a lithium disk with cadmium telluride @ all, cadmium telluride Um-sniffing can be doped with tellurium or cadmium in a slight excess upon request. Ru. For this purpose, the main coating material cadmium gold telluride evaporation chamber 2 and the coating material Charge tellurium and cadmium to gold evaporation chambers 3 and 4. Evaporation chamber 2 has a temperature of 460 to 520 ℃, the temperature of the evaporation chamber 3 is 350 to 420℃, and the temperature of the evaporation chamber 4 is 250 to 300℃. ℃ and the resulting vapor molecules emitted from the material pass from the evaporation chamber 2, 3.4 to the tube 13. It reaches the inside of the flow path 16 inside. The wall 14 of the tube 13 is heated to a temperature of 520-570°C. Ru. The tube 13 has a diameter of about 50 mm and a length of gas flow guide for steam flow of about 9011□. are doing. The distance between the outlet end 1T of the tube 13 and the support 6 to be coated is 45n. Selected.

After the support 6 is heated to a temperature of 200 to 450°C, the shutter 21 is rotated. The surface of the support 6 which is removed from the steam flow path and directed towards the pipe 13 is coated. Ru. The epitaxial film was formed at a support temperature of 350°C and a main coating material temperature of 500°C. A growth rate of 2.5 μm/h was achieved, and a uniform film thickness was obtained. support Deviation in film thickness measured optically and mechanically across the surface is less than 4% , not measured due to the measurement accuracy of the measurement method.

A residual gas pressure of approximately 10-10 mbar was maintained in the vacuum chamber during the deposition of the skin.

It goes without saying that the present invention is not limited to the illustrated embodiment. example For example, the holder 18 for the support 6 can be used to obtain a uniform film thickness t in the case of large-area supports. It can be additionally moved in a known manner in order to

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Claims (4)

[Claims] 1. The vapor obtained by heating at least one coating material is applied to the coating material. at least approximately constant flow lateral over the guiding length before condensing on the support surface. Depositing the coating on the support in vacuum by guiding it between hot walls forming a cross-section In this method, vapor is passed between hot walls under a free-flowing state of molecules. 1 (1/2) times the minimum diameter of the flow cross section before and guide the flow between the hot walls, and at the exit side the end of the flow cross section formed by the hot walls. Supports to be covered after an average flow distance corresponding to 1/2 to 2 (1/2) times the small diameter. Depositing a film on a support in a vacuum, characterized by condensation onto the surface of the support method for. 2. The steam leaving the hot wall is heated on the exit side before condensing onto the substrate surface to be coated. Corresponds to 1 to 1 (1/2) times the minimum diameter of the flow cross section formed by the wall. 2. The method of claim 1, wherein the average flow distance is free flowing. 3. Apparatus for carrying out the method according to claim 1 or 2, comprising: at least one evaporation chamber is provided, the evaporation chamber having at least a substantially constant flow horizontally; It communicates between heatable walls forming a flow channel with a cross section, and the axis of the flow channel Also provided with a holder for the support to be coated, which is arranged on the top. In this case, the length of the channel (16) between the heatable walls (14) is the maximum length of the channel (16). corresponds to at least 1 (1/2) times the small diameter, and the holder (18) is at the support position. from the outlet end (17) of the flow path (16) to the minimum outlet cross-section of the flow path (16) with respect to Placed in the vacuum chamber (1) at a distance of 1 (1/2) to 2 (1/2) times the diameter. A device characterized in that it is located at 4. The support (6) to be coated and the channel (16) measured in the direction of the axis of the channel (16) The distance between the outlet end (17) of the channel (16) and the outlet end (17) of the channel (16) is the minimum diameter of the outlet cross section of the channel (16). 4. The device according to claim 3, wherein the device corresponds to 1 to 1 (1/2) times of .