WO2016166079A1

WO2016166079A1 - Cold trap

Info

Publication number: WO2016166079A1
Application number: PCT/EP2016/057964
Authority: WO
Inventors: Thomas KRÜCKEN; Walter Franken
Original assignee: Aixtron Se
Priority date: 2015-04-13
Filing date: 2016-04-12
Publication date: 2016-10-20
Also published as: DE202015101792U1; TW201701935A; TWI685376B

Abstract

The invention relates to a device for condensing volatile components from a gas flow, said device comprising a housing, which has pot-shaped lower part (1) and a cover (2) that seals the opening of the lower part, an insert (3) arranged in the cavity of the lower part (1), which insert has an upstream section and a downstream section, wherein: the upstream section has a plurality of cooling elements (4) through which a coolant can flow, which elements are arranged at a first distance from one another, cross one or more gas flow channels (12) and extend in a parallel arrangement from an upper plenum (5) to a lower plenum (6); each of the two plena (5, 6) is fluidically connected to a coolant inlet (13) or to a coolant outlet (14); the insert (3) has gas guiding elements (10, 10', 21) in order to repeatedly divert the gas flow from a gas inlet (16) to a gas outlet (17); and wherein the downstream section of the insert (3) has second cooling elements (20), which are connected to the lower plenum (6) in a heat-conducting manner and which are at a second distance from one another, wherein the second distance is smaller than the first distance.

Description

description

cold trap

Field of engineering

[0001] The invention relates to a cleaning device for condensing volatile constituent of a gas stream, as used downstream of a reactor of a CVD coating plant, in particular a MOCVD plant. In a CVD coating apparatus, gaseous starting materials are introduced into a reactor where they react chemically with each other or with substrates contained in the reactor. The starting materials or the reaction products are volatiles in a gas stream leaving the reactor. The gas stream flows through a cold trap, which is cooled by a cooling medium, so that on surfaces of the cold trap, a condensation of the volatile constituents takes place, as long as the temperature of the wall is below the condensation temperature of the volatile constituent. With such a cold trap, the remaining process gases or the reaction products to be removed from the gas stream, which is subsequently further purified and / or flows through a vacuum pump.

State of the art

DE 299 04465 Ul describes a cold trap with mutually parallel cooling elements, which can be flowed through by a cooling liquid and which are arranged parallel to each other. From a first plenum, a cooling liquid is fed into the cooling elements. The cooling liquid exits the cooling elements into a second plenum. DE 86 25 127 Ul describes a cold trap in which a gas stream is diverted several times. DE 69736 124 T2 describes a cold trap with a housing in which a delgangartige cooling coil sits and the medium to be cooled must flow past cooled gas baffles.

Heat exchangers are known from US 4,142,580 and US 3,681,936

DE 2 537 639 AI describes a device for freezing solid components from vapor-gas mixtures, wherein a coolant is passed through a plurality of juxtaposed cooling elements. The cooling elements formed as tubes extend from a lower plenum to an upper plenum. The supply line to the lower plenum is made by a central supply pipe. DE 1 203 226 also describes a device for separating sublimatable substances, wherein side surfaces are fixed to cooling tubes whose distance decreases in the flow direction.

[0006] FR 2 146 100 describes a cold trap with a container which is insolated towards the outside and in which there is an inner container in which a cooling liquid is stored. The cooling liquid flows through a multiplicity of torus-shaped cooling channels.

US 7,067,088 B2 describes a polymerization reactor having a plurality of evenly spaced temperature exchange surface elements.

From US 4,538,423 a cold trap is known in which nitrogen is used as a coolant and temperature control wear a variety of gas baffles, so that the gas flow can meander through the cooling device. The distance between the gas flow channels formed by the gas guide plates decreases in the flow direction. Heat exchangers with mutually parallel heat transfer elements are also known from US 3,226,936 and WO 2011/135333 A2 and US 4,142,580 and US 3,681,936.

Summary of the invention

[0010] It is an object of the invention to specify a cold trap suitable for use in an MOCVD coating device, which has a lower risk of clogging of the gas flow channels.

The problem is solved by the invention specified in the claims, wherein the dependent claims represent not only advantageous developments of the solution specified in claim 1, but also independent solutions to the problem.

First and foremost, a device for condensing volatiles of a gas stream is proposed which has a housing. The housing has a cup-shaped lower part with an opening and a gas-tight closing the opening lid. The cover can rest gas-tight on the opening edge of the lower part by means of seals and be braced with the edge. There is a particular insertable through the opening into the cavity of the lower part insert provided. This can be firmly connected to the lid, so that after a release of the cover from the lower housing part of the insert can be removed by lifting the lid from the lower housing part. But it is also envisaged that the insert is releasably connected to the lid. The insert has a plurality of cooling elements. The cooling elements are arranged so that they cross a multi-section gas channel. For this purpose, the gas channel consists of a plurality of gas flow channels arranged one behind the other in the flow direction. The gas flow channels can be parallel to each other. to run. The cooling elements can likewise run parallel to one another and preferably transversely to the gas flow channels. It is an upper and a lower plenary provided. One of the Plena is fed by a coolant. The other of the Plena has a coolant drainage. The cooling elements extend from one plenum to the other plenum, preferably from an upper plenum to a lower plenum. The housing, which is a container, has a gas inlet and a gas outlet. The gas inlet may be formed by a pipe arranged near the opening pipe. The gas outlet may be formed by a pipe socket arranged near the bottom of the housing. By means of the pipe socket, a gaseous medium can pass through an opening in the wall of the container into the container and exit through a wall of the container again from the container. Inside the housing are gas guide elements, which redirect the gas flow from the gas inlet to the gas outlet several times. In this case, it is provided in particular that the gas flow diverted several times crosses the cooling elements several times. The cooling elements may be formed by rectilinear tubes which are held at their opposite ends in openings of plates forming walls of upper or lower plenums, respectively. The gas guide plates may be flat plate-shaped objects which are arranged parallel to the plates holding the free ends of the cooling elements. The Gasleitbleche may alternately have opposite gas passage openings, which are each arranged at the edge of the housing. A gas stream can thus be deflected in stages and meandering flow between two opposite wall portions of the preferably cylindrical housing. The gas stream flows in each case in the transverse direction to the cylinder axis of the housing via a guide plate, in order then to enter through an adjacent the wall of the housing arranged gas passage opening in an axially offset plane, and then below the Gasleitblechs in the opposite direction to flow another gas passage opening. In a particularly preferred embodiment, the gas flow channels have different free cross-sectional areas from each other. Free cross-sectional areas are to be understood as meaning the cross-sectional areas in which no flow guidance elements or cooling elements run, that is, for example, an area that is delimited by two opposing gas guide plates and two adjacent cooling elements. Since a plurality of cooling elements intersect the gas flow channel, the free cross-sectional area is many times smaller than the total cross-sectional area of the gas flow channel. These free cross-sectional areas are to be smaller according to an aspect of the invention in the flow direction. This can be achieved structurally by reducing the distance of parallel gas guide plates in the flow direction. It is also envisaged that for this purpose, the distances of cooling elements in the flow direction decreases. In detail, two adjacent cooling elements or two adjacent gas guide plates have a minimum distance from each other in a direction transverse to the flow direction. This minimum distance decreases in the direction of flow, so that the effective surfaces formed by the surfaces of the cooling elements, but also by the surfaces of the gas guide elements for the condensation of the volatiles increase in the flow direction. In particular, it is provided that the insert or the cooling volume of the container has two volume sections, wherein first cooling elements are arranged in an upstream section and second cooling elements are provided in a downstream section. The second cooling elements are more closely spaced than the first cooling elements. In an upstream region of the cold trap, the cooling surface flow volume ratio is smaller than in a downstream region, so that in an upstream region, the cooling performance is lower than in the downstream region. However, the larger free cross-sectional areas have the advantage that they adhere to the free surface. Chen the cooling elements or the Gasleitblechen thicker condensate layers can be deposited without clogging the gas flow channels, as in the downstream area, where a gas phase depletion has already taken place on the volatile components, so that there is to be reckoned with a lower deposition rate, as in the upstream region , In addition, it is proposed that the coolant flows in the opposite direction to the gas flow through the cavity of the container. With the coolant inlet in the lid of the housing, the coolant inlet is connected to a coolant line that directs the coolant to a lower plenum. The lower plenum is connected to the upper plenum with several parallel tubes. The coolant thus flows from bottom to top through the tubular cooling elements to the upper plenum, which is connected to a coolant outlet. On the other hand, the gas to be cleaned flows from top to bottom through the cold trap, where it is deflected several times, crossing the cooling elements several times. In the downstream section, further cooling of the gas takes place through the second cooling elements. It may also be to be flowed through by a cooling liquid tubes or lumens. However, it is also envisaged that the cooling elements in the second section are solid, preferably highly conductive bodies, in particular rods, which are connected to the plenum in a manner which is highly thermally conductive. The upper plenum and lower plenum may occupy equal volumes; however, the upstream portion preferably occupies a larger volume than the downstream portion. The volume ratios are preferably three quarters to one quarter. The cooling trap according to the invention is used in particular in the gas outlet system of a MOCVD system, wherein the gases used for dry etching or the reaction products formed during dry etching are frozen out inside the cold trap. The cold trap according to the invention is thus used in an in-situ cleaning step used. The inventive cold trap can be particularly chlorides of main group III, ie GaCl _x and A1C1 _X freeze.

Brief description of the drawings

In the following the invention will be explained in more detail with reference to an embodiment. Show it:

1 is a perspective view of a cold trap,

2 is a plan view of the cold trap,

3 shows the section along the line III-III in Figure 2,

4 shows the section along the line IV-IV in Figure 3,

5 shows the section along the line V-V in Figure 3,

6 is a half section in a perspective view,

Fig. 7 is a view according to Figure 1, wherein the attached to the cover 2

Insert 3 is removed from the lower housing part 1 is in a first perspective view and

Fig. 8 taken out of the lower housing part 1 insert 3 in a second perspective view. Description of the embodiments

The exemplary embodiment illustrated in the drawings is a cleaning device for use in the exhaust gas duct of a coating installation, for example a MOCVD coating installation, and is used for the deposition of layers or for in situ cleaning of the reactor of the coating installation extruded out gaseous reaction products or starting materials from a carrier gas stream. The device has a housing which consists of a lower housing part 1 and a housing cover 2. The lower housing part 1 is a cup-shaped body with a circular bottom 23 and with a cylindrical side wall 24. The side wall has in the region of its opening a fixedly connected to the side wall opening edge 7, which projects radially. Immediately below the opening edge 7 is a gas inlet 16 in the form of a pipe socket through which the exhaust gas to be cleaned can flow into the cylindrical internal volume of the container. Near the bottom 23 there is also a gas outlet 17 in the form of a pipe socket, through which the gas can emerge from the container. The container wall 24 has a large gas passage opening in the region of the gas inlet 16. The gas passage opening 27 of the wall 24 of the gas outlet 17 is smaller than the cross-sectional area of the gas outlet nozzle, so that the gas passage opening 27 is spaced from the bottom 23. It thus forms a ground level

Dead volume, in this Kondensatsammeivolumen can collect from the gas frozen condensate.

Surrounded by the opening edge 7 opening of the lower housing part 1 is closed by a housing cover 2. The housing cover 2 has a cover plate 8, which rests on the opening edge 7 with the interposition of a seal 25. There are provided a plurality of clamping elements 26, which cover the cover plate 8 with the interposition of the seal 25 against the opening. Pressing edge 7, so that the lower housing part 1 is gas-tightly closed by the housing cover 2.

Within the housing cavity of the lower housing part 1 is an insert 3. In the embodiment, the insert 3 is fixedly connected to the cover 2. But it can also be firmly connected to the lower housing part. The insert 3 consists essentially of a plurality of mutually parallel cooling elements 4, which are each formed by tubes. The upper mouth sections 4 'of the cooling elements 4 are stuck in openings of the cover plate 8, so that the tubular cooling elements 4 open into an upper plenum 5 arranged above the cover plate 8. The plenum 5 forms a collecting volume to collect cooling medium emerging from the cooling elements 4 and to transport it away through a coolant outlet 14. For this purpose, the coolant outlet 14 is seated on a plenum wall 9, which extends parallel to the cover plate 8. The existing in particular of a metal cooling elements 4 are connected with its second mouth end 4 "with a lower plenum 6. They put this in openings in a bottom plate 18 which is parallel to the cover plate 8 and the wall of the lower plenum 6 forms at A further base plate 19 bounds the lower plenum 6 downwards, and a coolant inlet 13 arranged in the region of the cover is connected to the lower plenum 6 via a coolant connection line 15, so that through the coolant inlet 13 fed cooling medium, for example, a cooling liquid, such as liquid nitrogen, ethanol, glycol or water can flow into the lower plenum 6, and then pass through the mutually parallel cooling elements 4 in the upper plenum 5, from which it emerges through the coolant outlet 14 , The cooling elements 4 are carriers of a plurality of mutually parallel Gasleitbleche 10. The Gasleitbleche 10 extend between the two Plena 5, 6 and have an outline contour, which is substantially a circular shape, so that with its edge to the inside the wall 24 reach. The Gasleitbleche 10, 10 'have an edge portion which extends approximately 60 to 90 °, which is spaced from the wall 24, so that there forms a gas passage opening 11, through which in an upper flow channel 12, 12' flowing gas stream can flow through into an underlying flow channel 12. The gas passage openings 11 are alternately facing each other, so that the gas flow zigzag flows from the gas inlet 16 to the gas outlet 17.

The distance of the uppermost lying Gasleitblechs 10 'of the cover plate 8 is greater than the distance of the second Gasleitblechs 10 to uppermost lying gas guide plate 10'. It is further provided that the distances of the Gasleitbleche 10, 10 'in the flow direction of the gas stream, that is reduced in the axial direction of the container from top to bottom, so that the free flow cross-section of the gas flow channels 12, 12' decreases in the flow direction.

The lower plenum 6 is located above the gas outlet 17 and limits about three quarters of the volume of the container down. In the lower quarter of the container volume is a second cooling section with second cooling elements 20, which are formed in the embodiment of highly conductive cylindrical rods. The second cooling elements 20 are spaced less than the first cooling elements 4, so that the flow channels in the lower portion have a smaller free cross-sectional area. But it is also envisaged to form the second cooling elements 20 as tubes and to flow through with a cooling medium. In the exemplary embodiment, the cooling bars are be 20 connected at one end to the bottom plate 19, which is cooled by the inflowing cooling medium. The free ends of the cooling rods 20 protrude directly to the bottom 23 of the housing zoom.

Above the gas outlet 17, two cooling plates 21, which are spaced from each other or to the bottom plate 19 closer than the Gasleitbleche 10 of the upper portion extend from each other or from the bottom plate 18 or the cover plate. 8

The lower plenum 16 forms an edge-side gas passage opening 22, through which the gas to be purified can flow from the first section into the second section. It flows around the gas guide plates 21 as well as the Gasleitbleche 10 in a direction transverse to the axial direction of the container and passes in the radial direction through gas passage openings 22 therethrough.

[0023] The above explanations serve to explain the inventions as a whole, which in each case independently further develop the state of the art, at least by the following feature combinations, namely:

A device, characterized by condensing out volatiles of a gas stream with a housing having a cup-shaped lower part 1 and a cover 2 closing the opening, with an arranged in the cavity of the lower part 1 insert 3, which has a plurality of cooling elements 4 which intersect one or more gas flow channels 12 and extend in a parallel arrangement from an upper plenum 5 to a lower plenum 6, the two plenums 4, 5 respectively communicating with a coolant inlet 13 or with a coolant outlet 14 are, wherein the insert 3 Gasleitelemente 10, 10 ', 21, to divert the gas flow from a gas inlet 16 to a gas outlet 17 multiple times.

[0025] A device which is characterized in that the gas flow channels 12, 12 'arranged one behind the other in a flow direction of the gas have free cross-sectional areas which become smaller in the flow direction.

A device which is characterized in that the gas flow channels 12, 12 'by parallel arranged gas guide plates 10, 10', 21 are limited. A device which is characterized in that the distance between the gas guide plates 10, 10 ', 21 in the flow direction is smaller.

A device, characterized in that a first, upstream portion of the insert 3 comprises first cooling elements 4, which are arranged at a first distance from each other and a downstream second portion of the insert 3, second cooling elements 20 having a second distance have each other, wherein the second distance is smaller than the first distance.

A device which is characterized in that a coolant can flow through the first cooling elements 4 and the second cooling elements 20 can either be flowed through by a coolant or in heat-conducting connection to a plenum 6. A device, characterized in that the first portion fills about three quarters of the total volume of the housing and the second portion fills about a quarter of the total volume of the housing.

A device which is characterized in that the insert 3 is fixedly connected to the cover 2 and a cover plate 8 forms a wall of the upper plenum 5.

[0032] A device which is characterized in that the gas guide plates 10, 10 ', 21 have gas passage openings 11, 22 for diverting a gas flowing in above the gas guide plate 10, 10', 21 into an opposite direction of flow below the gas guide plate 10, 10 ', 21, so that the gas flow is deflected several times in a meandering manner, the cooling elements 4, 20 passing through the cold trap with multiple crossing.

A device which is characterized in that the gas inlet 16 is arranged near the opening of the housing lower part 1 and the gas outlet 17 is arranged near the bottom 23 of the housing lower part 1.

A device is characterized by a gas passage opening 27 for the exit of the gas flow from the cold trap, wherein the gas passage opening 27 is spaced from the bottom 23 of the housing lower part 1.

A device, which is characterized in that the flow of the coolant passing through the cooling elements 4 cooling medium is opposite to the flow direction of the gas stream.

All disclosed features are essential to the invention (individually, but also in combination with one another). In the disclosure of the application will hereby also the content of the disclosure of the associated / attached priority documents (copy of the prior application) fully incorporated, including for the purpose of including features of these documents in claims of the present application. The subclaims characterize with their features independent inventive developments of the prior

Technology, in particular to make divisional applications based on these claims.

List of reference numbers

1 housing base 20 cooling element

2 upper housing part 21 gas guide plate, cooling plate

3 insert 22 gas opening

4 cooling element 23 bottom

4 'mouth section 24 tank wall, side wall

4 "Mouth-end 25 gasket

5 upper plenum 26 clamping elements

6 lower plenum 27 gas passage opening

7 opening edge

8 cover plate

9 Plenary wall

10 gas baffle

10 'gas baffle

11 gas passage opening

12 gas flow channel

12 'Gaströmungskanal

13 coolant inlet

14 coolant outlet

15 coolant connection line

16 gas inlet

17 gas outlet

18 base plate

19 base plate

Claims

claims

A device for condensing volatiles of a gas stream with a housing having a cup-shaped lower part (1) and a lid (2) closing the opening, with an in the cavity of the lower part (1) arranged insert (3), the upstream and a downstream portion, wherein the upstream portion has a plurality of cooling elements (4) through which a coolant can flow, which are arranged at a first distance from one another and which intersect one or more gas flow channels (12) and in a parallel arrangement from an upper one Plenum (5) to a lower plenum (6) extend, wherein the two Plena (4, 5) each with a coolant inlet (13) or with a coolant outlet (14) are fluid-connected, wherein the insert (3) Gasleitelemente (10 , 10 ', 21) to redirect the gas flow from a gas inlet (16) to a gas outlet (17) several times, and wherein the downstream ige portion of the insert (3) second cooling elements (20) which are in thermal communication with the lower plenum (6) and which have a second distance from each other, wherein the second distance is smaller than the first distance.

2. Apparatus according to claim 1, characterized in that in a flow direction of the gas successively arranged gas flow channels (12, 12 ') have free cross-sectional areas which are smaller in the flow direction.

3. Device according to one of the preceding claims, characterized in that the gas flow channels (12, 12 ') by mutually parallel Gasleitbleche (10, 10', 21) are limited.

4. Device according to one of the preceding claims, characterized in that the distance of the Gasleitbleche (10, 10 ', 21) in the flow direction is smaller.

Device according to one of the preceding claims, characterized in that the first portion fills about three quarters of the total volume of the housing and the second portion fills about a quarter of the total volume of the housing.

Device according to one of the preceding claims, characterized in that the insert (3) is fixedly connected to the cover (2) and a cover plate (8) forms a wall of the upper plenum (5).

Device according to one of the preceding claims, characterized in that the Gasleitbleche (10, 10 ', 21) Gasdurchtrittsöffnun- conditions (11, 22) for diverting a gas flowing above the Gasleitblechs (10, 10', 21) gas in an opposite direction of flow below the Gasleitbleches (10, 10 ', 21), so that the gas flow meandering several times deflected, the cooling elements (4, 20) passes through the cooling trap multiply crossing.

Device according to one of the preceding claims, characterized in that the gas inlet (16) near the opening of the housing lower part (1) is arranged and the gas outlet (17) near the bottom (23) of the housing lower part (1) is arranged.

9. Device according to one of the preceding claims, characterized in that the gas inlet (16) the upstream portion and the gas outlet (17) are associated with the downstream portion.

10. Device according to one of the preceding claims, characterized by a gas passage opening (27) for the exit of the gas flow from the cold trap, wherein the gas passage opening (27) from the bottom (23) of the housing lower part (1) is spaced.

11. Device according to one of the preceding claims, characterized in that the flow of the through the cooling elements (4) passing through the cooling medium of the flow direction of the gas stream is directed opposite.