DE19813523C2 - CVD reactor and its use - Google Patents

Abstract

Described is a CVD reactor with DOLLAR A - a reactor housing with a lid, DOLLAR A - a heated susceptor (wafer carrier) arranged in the reactor housing, on which at least one wafer can be arranged, DOLLAR A - a central fluid inlet, through which temperature-controlled in particular CVD media etc. enter the reactor, and DOLLAR A - a fluid outlet located on the periphery of the reactor housing and through which the admitted media exit. DOLLAR A The invention is characterized in that the fluid outlet has approximately the shape of a disk with a plurality of outlet openings for the CVD media etc. and is arranged between the susceptor (wafer carrier) and the reactor cover in such a way that the fluid outlet is caused by radiation from the susceptor (Wafer carrier) is heated and thus adjusts to a temperature between the temperature of the susceptor (wafer carrier) and the reactor cover, through which the CVD media etc. enter at a temperature.

Description

The invention relates to a CVD reactor according to the preamble of claim 1, and its use.

CVD reactors are generally known and are used, for example, by manufactured and distributed by Aixtron AG, Aachen, DE. On this known  CVD reactors are not described in detail in the explanation of all here expressly referenced terms.

The known CVD reactors have a reactor housing with a Cover in which a heated susceptor (wafer carrier) is provided, on which at least one wafer can be arranged. As an inlet for CVD gases or liquids are usually a central fluid inlet intended. The fluid outlet is then mostly at the circumference of the reactor arranged housing.

Either central gas inlet nozzles (gas inlet Nozzles) which move the gases from the center of the reactor radially across the wafer let out, or so-called shower heads in or on Reactor covers are used, which are arranged directly above the wafer, and from a lot of small holes the gas in the form of a shower vertical spray down onto the wafers. Such reactors are for example distributed by Thomas Swan, GB.

DE 43 30 266 discloses a similar structure according to the one zel wafer reaction chamber a wafer heater stage for holding a Wafers down and to heat the wafer. Continue there is a gas inlet nozzle opposite the wafer heating stage transmitter gas supply head, creating an area with constant distance to supply reaction gas. Via the gas supply head gases are flown out over the wafer. An exhaust outlet exists Likewise.  

Now there are materials for which it is advantageous if the gases are tempered be let into the reactor. You can achieve this by that the gases are preheated or that the inlet is heated.

For fluid inlets designed as shower heads, it is be knows the shower head with complicated water channels Equip thermostat. This configuration does not only have that Disadvantage that it is complex and therefore expensive, but also the night part that the use of water channels in CVD reactors always a ge represents some risk. For example, in the event of a leak Cooling water exit into the interior of the reactor and with the or React explosively to CVD gases. Another disadvantage is that with the Water heating associated temperature inhomogeneity in the shower head (showerhead).

According to DE 43 30 266, the gas is supplied via a gas supply head and its gas inlet nozzles in the area at a constant distance above directed a wafer. Here, too, the temperature of the Gases through a cooling water path and a heat conservation element influences. The temperature of the inner wall of a room element, which is adjacent to the gas inlet areas at a constant temperature held. The disadvantages mentioned above also apply here for water channels.

The invention has for its object a CVD reactor with a flui designed as shower heads or gas inlet nozzles inlet to develop such that the fluid inlet and thus the inlet send fluids, i.e. gases and / or liquids in a simple manner and  be tempered in particular without water channels etc. can.

An inventive solution to this problem is in claim 1 specified. Further developments of the invention are the subject of the claims che 2 following. In claims 31 and 32 are methods under Ver claimed use of a reactor specified according to the invention.

According to the invention, a CVD reactor is developed with the features listed in the preamble of claim 1,

• - That the fluid inlet unit is spaced from the reactor cover Has hollow body, the underside in which the openings are featured are seen, essentially by heat radiation from the susceptor (Wafer carrier) is heated,
• - That a purge gas inlet device is provided, which in the Zwi space between the top of the hollow body and the reac introduces a purge gas such that the top heat in the essentially by heat conduction in the gas to the environment there, and
• - That the heat supply and dissipation conditions to or from the hollow body are set so that the underside without feeding a Temperature control medium from the outside to a selectable temperature which the CVD media are tempered, and that between the top and bottom of the hollow body a positive tem temperature gradient exists.

CVD media are used in the context of the present description CVD and in particular MOCVD gases, liquids, solutions or  Mixtures of the above substances - in the following also generally with the The generic term "fluid" denotes - understood.

According to the invention, a known CVD reactor is thus continued forms that the fluid inlet unit has a unit which is approximately the Shape of a hollow disc with a large number of outlet openings for the CVD media etc. - a shower head known per se (shower head) - and between the susceptor (wafer carrier) and the reactor lid is arranged so that the bottom of the fluid inlet unit through Radiation from the susceptor (wafer carrier) is heated, and thus on a temperature between the temperature of the susceptor (wafer carrier) and the reactor cover, so that the CVD media etc. at the Pas the fluid inlet unit are tempered. Because at the top of the Fluid inlet unit is an (adjustable) heat sink is provided a certain temperature in the axial direction via the fluid inlet unit gradient.

The invention is based on the basic idea, the complicated Construction of known reactors in which the thermostatting of the Re actuator cover and the gas inlet in the form of a liquid poured showerhead and the required separate heater zaggregate takes place by simplifying that the shower head (Showerhead) separated from the reactor cover as a separate component. Since the susceptor (wafer carrier) anyway by an infrared heater, one Resistance heating or high frequency heating to one temperature between typically approx. RT ° C and 1200 ° C (RT stands for room temperature rature) is heated, and thus a considerable amount of heat Emits radiation to its surroundings, the fluid inlet unit is opened  heats. The temperature according to the invention increases which the fluid inlet unit is heated, adjusted in a controlled manner.

It is preferable to bring one made of a highly thermally conductive metal made a thin shower head in the reactor below the Reactor lid and optionally below a thermostatted Ceiling.

This structure has a number of advantages:

The shower head is directly exposed to the radiation from below Heated susceptor. In particular, the distance between The susceptor (wafer carrier) and hollow body for setting the temperature rature of the underside of the hollow body to be adjustable. For this, a Holding unit for the hollow body can be provided with a thread.

The heat supply or dissipation to or from the hollow body is controlled by the tem temperature of the susceptor (wafer carrier), the now freely adjustable distance to the susceptor (wafer carrier), and the conductivity of the gas in the reactor (Choice of the carrier gas, for example nitrogen or hydrogen or a mixture of these gases and total pressure). A previously necessary Provision of an additional heating unit for heating and temperature There is no need for the shower head.

The heat dissipation from the top of the shower head (shower head) path is determined by the purge gas above the shower head (showerhead) and the quartz ceiling (quarz ceiling) and which Purge gas between quartz ceiling and metal reactor lid is used.  

In particular, that of Frijlink et al. proposed thermo statized ceiling can be used. In this respect, the Use of two purge gas mixtures, the absolute temperature and the Temperature gradient of the shower head in the reactor very pre zise adjustable or adjustable.

Above all, the positive that is desired in most applications Temperature gradient from shower head to susceptor (wa ferträger) automatically guaranteed. The temperature gradient can be too are additionally influenced in a controlled manner by a further configuration, by locally using heat shields and a multi-layer version of the Showerhead (showerhead) with materials introduced below have different reflection and absorption coefficients.

Otherwise, the reactor is constructed conventionally: In particular, the Reactor a round reactor - similar to the well known planetary reactor - with central gas inlet and external gas outlet (exhaust) his. The gas outlet (exhaust) can in particular that of Frijlink et al. proposed tunnels. The ceiling of the reactor can also be like the ceiling proposed by Frijlink and thus ther be mostatizable.

The susceptor (wafer carrier) is either a planetary susceptor (tarpaulin wafer carrier) with double rotation or just one large single slice be, which are also based on gas foil rotation (i.e. rotation of the wafers on a Gas cushion; Patent of the applicant Aixtron) or mechanically ro animals. In the latter case, you can only use one wafer at a time, but for that  place larger wafers centrally. Alternatively or additionally, it is possible to rotate the fluid inlet device about its axial axis.

For the layer production of multi-component material systems e.g. B. related to β-diketonates or other organometallic solutions, Mixing them now takes place directly in the shower head can be carried out by constructive establishment of one or more Inlets in the shower head, with the same or different temperature. On the other hand, the shower head can also be designed such that different gases are separately in the shower head (Showerhead), and mixing only when leaving from the shower head into the reactor space to para to avoid critical pre-reactions.

The risk of additional cooling water near the gas inlet There is no need to use thermostatting. The shower head is much easier to adjust and replace. The reactor becomes very flexible, because the most diverse shower heads are very quick can be used and exchanged for different wafers sizes, without major changes to the reactor, disassembly or opening media lines. The reactor is thermal from all sides true, and all walls are heated, so that minimal deposits stand.

Another advantage is that any existing planetary reactor is very simple can be converted since the fluid inlet unit is fully compatible with conventional ones Intakes.  

The reactor according to the invention can be used for all types of CVD processes are used, e.g. B. to apply or edit III-V, II-VI, IV-IV materials, also of single and multi-component oxides, Perovskites such as B. barium and strontium titanate (ST and BT), Bari um strontium titanate (BST), strontium and barium zirconate titanates, Strontium bismuth tantalate (SBT), lead zirconate titanate (PZT), as well as from with acceptor and / or donor doping listed above material systems.

Another advantage is that the shower heads are very light are interchangeable. This makes it possible, depending on the wafer shape used To use shower heads, their hole or outlet arrangement the arrangement and shape of the wafers arranged underneath speaks, so that a very homogeneous, yet economical processing or coating of the wafers is possible.

In addition, the reactor designed according to the invention can also be used Etching or cleaning fluids are operated in order to discharge any Wrong or remove condensates as quickly as possible (self cleaning). In this design, the reactor is switched off with a shower head a material that is resistant to the etching gas.

Furthermore, the reactor can be operated with a normal gas supply system operated, or with a source distribution system (Liquid delivery system) or aerosol system that already gases periert feeds (so-called LDS system).  

The rotation speed is in the case of double rotation (tarpaulin rotation) is relatively slow and is typically between 10 and 200 Revolutions per minute (rpm).

If only one wafer is used centrally, a wide variety of rota can be used tions between 5 and 1500 revolutions per minute (rpm) are used the.

The invention is hereinafter without limitation of the general Er inventive idea based on an embodiment with reference Taking the drawing as an example, whose

only figure shows a schematic cross section shows by a device according to the invention.

The CVD reactor shown in cross section in the figure has a reactor vessel 1 with a reactor cover 2 . The reactor vessel 1 and the lid 2 are water-cooled in the exemplary embodiment shown, so that they are always approximately at room temperature. In the reactor vessel 1 , which may in particular have a cylindrical shape, a gas outlet 21 is provided in a manner known per se.

In the interior of the reactor vessel 1 there is also a susceptor (wafer carrier) 3 for wafers 4 which are to be processed or coated by means of a CVD process. The susceptor (wafer carrier) 3 is heated to a temperature between approx. RT ° C. and 1200 ° C. (RT stands for room temperature) by means of a heating device 5 , which may be an infrared heater, a resistance heater or a high-frequency heater.

Above the susceptor (wafer carrier) 3 is a fluid inlet unit 6 arranged, which has the shape of a hollow disc in the embodiment shown. In the bottom 6 'of the unit 6 , a variety of holes (shown schematically in the figure) are seen before, the arrangement of which can be adapted to the shape of the wafer 4 . The distance between the fluid inlet unit 6 and the susceptor (wafer carrier) 3 is adjustable, for example, via a thread.

Lines 71 to 73 open into the interior of the hollow disc 6 , through which gases and in particular CVD gases flow from a gas supply unit, not shown but otherwise known, which may have a preheating device, into the interior of the hollow disc 6 . The gases then emerge from the interior through the holes (not shown) and act homogeneously on the wafer 4 .

A heat shield 8 , also referred to as a ceiling, is provided between the hollow disc 6 and the underside of the reactor cover 2 . The heat shield 8 is a plate made of a heat-resistant and inert material, in the exemplary embodiment shown the plate consists of quartz.

Furthermore, a purge gas inlet device is provided which is connected to the reactor via lines 91 and 92 . The line 91 opens into the space between the heat shield 8 and the top of the hollow disk 6 , the line 92 opens into the space between the reactor cover 2 and the heat shield 8 . The purge gas inlet device is designed in such a way that the composition and / or the throughput of the gas or gases introduced into the space or spaces above the top of the hollow body can be changed in order to adjust the heat dissipation conditions. The heat supply and dissipation conditions to or from the hollow body 6 can be set such that the underside without the supply of a temperature medium from the outside to a selectable temperature by which the CVD media are tempered, and that between the top and there is a positive temperature gradient on the underside of the hollow body. This avoids clogging of the holes. There is also a positive temperature gradient to the susceptor (wafer carrier).

Claims (32)

1. CVD reactor with

• 1. a reactor housing with a housing cover,
• 2. a heated susceptor (wafer carrier) arranged in the reactor housing for one of the several wafers,
• 3. a fluid inlet unit with a multiplicity of openings facing the wafer or wafers, through which in particular tempered CVD media enter the reactor, and
• 4. a fluid outlet, which is arranged on the circumference of the reactor housing and through which the inlet media exit again,

characterized by

• 1. that the fluid inlet unit has a hollow body spaced from the reactor cover, the underside of which the openings are provided is heated essentially by heat radiation and / or by heat conduction from the susceptor (wafer carrier),
• 2. that a purge gas inlet device is provided which in the inter mediate space between the top of the hollow body and the Reak tordeckel initiates a purge gas such that the top gives off heat essentially by conduction in the gas to the environment, and
• 3. that the heat supply and dissipation conditions to or from the hollow body are set such that the underside adjusts to a selectable temperature, by means of which the CVD media are tempered, from outside without the addition of a temperature control medium, and that between the top and the underside of the hollow body has a positive temperature gradient.

2. Reactor according to claim 1, characterized in that the distance between susceptor (Wafer carrier) and hollow body for adjusting the temperature of the Bottom of the hollow body is adjustable. 3. Reactor according to claim 2, characterized in that a stop for adjusting the distance Unit for the hollow body is provided with a thread. 4. Reactor according to one of claims 1 to 3, characterized in that the reactor cover is thermostatted. 5. Reactor according to claim 4, characterized in that the reactor cover with cooling means of a liquid medium, such as water. 6. Reactor according to one of claims 1 to 5, characterized in that between the reactor cover and the A heat shield is provided on the top of the hollow body. 7. Reactor according to claim 6, characterized in that the heat shield is a plate of egg a heat-resistant and inert material such as quartz. 8. Reactor according to claim 6 or 7, characterized in that the purge gas inlet device has a first gas outlet in the space between the reactor cover and Heat shield and a second gas outlet in the space between the heat shield and the top of the hollow body.   9. Reactor according to one of claims 1 to 8, characterized in that the purge gas inlet device is such is that the composition and / or the throughput of the or in the spaces above the top of the hollow body introduced gases to adjust the heat dissipation conditions is changeable. 10. Reactor according to claim 9, characterized in that the purge gas inlet device under different gases or gas compositions between the upper side of the hollow body and the heat shield and the heat shield and initiates the reactor cover. 11. Reactor according to claim 9 or 10, characterized in that the flushing gas inlet device initiates a gas mixture of gases with different heat conduction, such as from H ₂ and N ₂ . 12. Reactor according to one of claims 1 to 11, characterized in that the hollow body made of a metal with good thermal conductivity or from several layers of different Metals with different thermal conductivities, reflection and Absorption properties exist. 13. A reactor according to claim 12, characterized in that the hollow body has a low heat has capacity.   14. Reactor according to claim 12 or 13, characterized in that the hollow body is a thin disc is. 15. Reactor according to one of claims 1 to 14, characterized in that the susceptor (wafer carrier) a pla netensusceptor (planetary wafer carrier) with double rotation. 16. Reactor according to one of claims 1 to 14, characterized in that the susceptor (wafer carrier) a Disc is. 17. Reactor according to claim 16, characterized in that the disc mechanically or on a Gas cushion rotates. 18. Reactor according to one of claims 1 to 17, characterized in that the hollow body or parts of the hollow body is rotatable, and the disc and / or the Sus zeptor is not turned. 19. Reactor according to one of claims 1 to 18, characterized in that the fluid inlet unit is so constructed det is that gases and / or liquids, such as metal in particular organic solutions can be mixed in the hollow body. 20. Reactor according to one of claims 1 to 18, characterized in that the fluid inlet unit is so constructed  det is that they have separate openings for different fluids points. 21. Reactor according to claim 20, characterized in that the respective openings are such arranges that the fluids after they emerge from the openings be mixed. 22. Reactor according to one of claims 1 to 21, characterized in that an additional temperature control device is provided which the fluids before they enter the hollow body warmed up. 23. Reactor according to one of claims 1 to 22, characterized in that the fluid inlet unit is so constructed det is that they are resistant to an etching or cleaning gas is. 24. Reactor according to one of claims 1 to 23, characterized in that the reactor is a circular cylindrical Shape. 25. Reactor according to one of claims 1 to 24, characterized in that the side walls of the reactor are thermostated. 26. Reactor according to one of claims 1 to 25, characterized in that the pressure inside the reactor is between 0.1 and 1000 mbar.   27. Reactor according to one of claims 1 to 26, characterized in that the fluid inlet unit contains the CVD media with pressures between 0.1 and 10 bar. 28. Reactor according to one of claims 1 to 27, characterized in that an infrared heater, a counter auxiliary heating or high-frequency heating the susceptor (Wa ferträger) heated. 29. Reactor according to claim 28, characterized in that the heating the susceptor (Waferträ ger) to a temperature between room temperature and 1200 ° C. heats up. 30. Reactor according to one of claims 1 to 29, characterized in that in addition to the heat shield between The upper side of the hollow body and the reactor cover further heat shields are provided. 31. Use of the device according to one of claims 1 to 30 for Production of thin layers from III-V, II-VI, IV-IV materials, furthermore of single and multi-component oxides, perovskites, in particular right barium and strontium titanate (ST or BT), barium strontium Titanate (BST), strontium and barium zirconate titanates (BZT), stron tium bismuth tantalate (SBT), lead zirconate titanate (PZT). 32. Use according to claim 31 for the production of thin doped and in particular acceptor or donor-doped layers.