WO2012143257A1

WO2012143257A1 - Device and method for depositing semi-conductor layers while adding hcl for surpressing parasitic growth

Info

Publication number: WO2012143257A1
Application number: PCT/EP2012/056418
Authority: WO
Inventors: Daniel Brien; Martin Dauelsberg; Gerhard Karl Strauch; Dirk Fahle
Original assignee: Aixtron Se
Priority date: 2011-04-18
Filing date: 2012-04-10
Publication date: 2012-10-26
Also published as: DE102011002146A1; DE102011002146B4; TW201250790A

Abstract

The invention relates to a device and a method for depositing II-VI- or III-V-semi conductor layers on one or more substrates (4). Said device comprises a reactor housing having a treatment chamber (1) arranged in the reactor housing, a susceptor (2) arranged in the process chamber (1) for receiving the substrate (4), a heating device (18) for heating the susceptor (2), a gas inlet element (7) comprising a gas mixture/supply device (34) provided with a source (31) for the metal-organic components, a source (30) for a hydrid, and a source (32) for the halogen components. The sources (30, 31, 32) are connected to the gas inlet element (7) in order to introduce the gases in separate gas flows into the heated treatment chamber (1). According to the invention, in order to reduce a parasitic deposition of a suspector upstream of the substrate, the gas inlet element (7) comprises several gas inlet areas (8, 9, 10) which are separate from each other. A halogen component inlet area (10), which is connected to the halogen component source (32), is arranged directly in front of a heated surface section (15) of the treatment chamber and is the nearest to said surface section.

Description

Apparatus and method for depositing semiconductor layers with HCl addition to suppress parasitic growth

The invention relates to a device for depositing II-VI or III-V semiconductor layers on one or more substrates, comprising a reactor housing having a process chamber arranged in the reactor housing, a susceptor arranged in the process chamber for receiving the substrate, a heating device for heating the susceptor a Suszeptortempe- temperature, a gas inlet member, which is associated with the process chamber to possibly together with in each case in a carrier gas process gases in the form of a V or VI component, in particular a hydride, an organometallic II or III component and a Halogen component in the process chamber to initiate, and a gas outlet device for the exit of reaction products and possibly the carrier gas from the process chamber, with a gas mixing / supply device comprising a source of the organometallic component, a source of the V or VI component, in particular the hydride and a source of the halo gene component, wherein the sources via delivery lines, and controllable by a control device valves and mass flow controller, are connected to the gas inlet member to the organometallic component, the V or VI component, in particular the hydride and the halogen component in separate gas flows, if necessary together with the carrier gas to bring into the heated process chamber, being fed in successive process steps by means of the controlling the valves and the mass flow controller control device process gases in a different composition from each other in the process chamber. The invention further relates to a method for depositing II-VI or III-V layers on one or more substrates, wherein process gases in the form of an organometallic II or III component, a V or VI component, in particular a hydride and a halogen component is provided in a gas mixing / supply device, the at least one substrate is applied to a susceptor in a process chamber, the susceptor and at least one process chamber wall are heated to a susceptor temperature or wall temperature, the process gases optionally together with a carrier gas in separated gas flows are introduced by means of a gas inlet member into the process chamber, where the organometallic component and the V or VI component, in particular the hydride pyrolytically react with each other at the substrate surface, so that a layer is deposited on the substrate, and the halogen component is a parasitic Partikelbildun g is reduced or suppressed in the gas phase and the carrier gas together with reaction products through a gas outlet device leaves the process chamber, being fed in successive process steps by means of the valves and the mass flow controller driving control process gases in different composition in the process chamber.

DE 102007009145 AI describes a device according to the preamble of claim 1. The device described there for performing a MOCVD method has three superimposed gas inlet zones through which different process gases can be introduced into the process chamber. Through a gas inlet zone adjacent to the susceptor, NH3, a gas inlet zone adjacent to the process chamber ceiling, inter alia HCl and through a gas inlet zone located therebetween organometallic component introduced. The introduction of the process gases takes place together with a carrier gas.

No. 7,585,769 B2 describes a device or a method for depositing III-V semiconductor layers on a substrate in a reactor housing. The process gases introduced into the process chamber of the reactor housing contain a hydride, for example ammonia, an organometallic component, for example trimethylgallium, and a halogen component, for example hydrogen chloride. The apparatus has a gas inlet member disposed vertically above a susceptor which extends in the vertical direction and carries a substrate which is heated to a process temperature using heaters. The halogen component should either be introduced together with the other process gases or separately into the process chamber and there should prevent or suppress the formation of particles in the gas phase.

US 4,961,399 A describes an apparatus for depositing III-V layers on a plurality of substrates arranged around a center of a rotationally symmetrical process chamber. A gas inlet member is arranged in the center of the process chamber and serves to introduce a hydride, for example NH3, A5H3 or PH3. In addition, organometallic compounds, which may be, for example, TMGa, TMIn or TMA1, are introduced into the process chamber through the gas inlet element. Together with these process gases, a carrier gas, in particular in the form of hydrogen, is introduced into the process chamber. The susceptor is heated from below. This can be done by means of thermal radiation, by means of high-frequency coupling or otherwise. A useful heater, which is arranged below the susceptor is described in DE 102 47921 AI. at In such a CVD reactor, the process chamber extends in a horizontal direction, is bounded below by a susceptor and at the top by a ceiling plate. DE 10 163 394 A1, DE 10 2006 018 515 A1 and US 2008/0132040 Al describe the use of HCl for etching the process chamber after a coating process or the use of HCl as a transport gas for gallium or indium in an HVPE process , DE 10 2004 009 130 A1 describes a MOCVD reactor with a process chamber arranged symmetrically about a central gas inlet member. Trimethylgallium and ammonia are introduced into the process chamber together with hydrogen. This paper also deals with theoretical considerations of the growth process. The process gases are introduced into the process chamber at an inlet temperature that is at room temperature or below 100 ° Celsius. The ceiling of the process chamber is kept at a ceiling temperature of less than 500 ° Celsius. The substrate temperature is in the range of about 1000 ° Celsius. Depending on the process gas used or the desired process success, these temperatures vary by 50 ° to 100 ° Celsius. In a flow zone, which adjoins directly to the gas inlet member, the process gases introduced into the process chamber and the carrier gas are heated. This is done essentially via heat conduction. The heat is introduced via the contact of the carrier gas with the process chamber ceiling or the susceptor in the gas phase. Since the susceptor temperature is higher than the top temperature, a so-called cold finger protruding in the direction of flow into the process chamber is formed, ie a spatial zone within the process chamber within which the carrier gas and in particular the process gases are heated. As process gases are such used, which decompose when heated in decomposition products; For example, the organometallic compounds gradually decompose via intermediate products into elemental metals, for example, TMGa decomposes via DMGa and MMGa into Ga. The hydrides decompose to a much lesser extent and are therefore offered in excess in process control. The growth rate of GaN on the substrate surface in this example is thus determined by the offer of TMGa.

The growth zone adjoining the flow zone is - according to previous knowledge - the area within the process chamber, within which at least the III component is almost completely decomposed, that is essentially only decomposition products or only metal atoms in the gas phase are present. These diffuse from the volumetric flow above the substrates arranged in the growth zone in the direction of the substrate surface, where the decomposition products are completely decomposed and the hydride decomposes stoichiometrically. Growth is described in previous theories of a boundary-layer diffusion model. The offer, ie the partial pressure of the III component, is selected such that the decomposition products are pyrolytically deposited on the substrate surface in the form of a crystal. The surface of the substrate is therefore also monocrystalline.

US 2008/0050889 deals with simulation calculations to determine suitable process parameters in order to suppress parasitic particle formation in a showerhead reactor.

DE 10 2004 009 130 A1 shows on the basis of FIG. 2 that the growth rate within the growth zone decreases in the direction of flow. By a suitable process management can be a straight line of the decrease of Set growth rate. The reason for the decline in the growth rate is the steady depletion of the gas phase due to the actual growth process. If the substrates are rotated by rotating substrate holders, this depletion effect can be compensated.

Homogeneous layer growth on the substrates lying on rotationally driven substrate holders requires a substantially linear course of the depletion curve or the growth rate in the growth zone in which the at least one substrate lies. In order to achieve such a depletion curve, the process parameters such as gas flows, total gas pressure and temperature must be set so that the maximum of the growth rate in a zone immediately before the growth zone, ie at the downstream end of the flow zone. This has the consequence that in the course of the growth process immediately before the growth zone parasitic layer growth takes place on the susceptor surface. Such layer growth is disadvantageous for at least two reasons. On the one hand, it leads to a depletion of the gas phase, since the decomposition products growing up on the susceptor surface in the downstream region of the flow zone are not available for the actual layer growth. On the other hand, the parasitic deposits lead to unwanted releases of previously deposited material thus undesirable transients. This is disadvantageous, in particular, when several layers each having a different layer composition and, in particular, differently doped layers are deposited one above the other. A disadvantage is also a particle formation in the gas phase within the growth zone, since such particles are conveyed out of the process chamber via the gas flow, without which contribute to the growth of the layer. In "High-growth rate process in a SiC horizontal CVD reactor using HCl", Micronicelectronic Engineering 83 (2006) 48-50, the authors describe the effect of HCl with respect to suppression of silicon nucleation. The authors also describe the effect of additional HCI flow in the deposition of silicon-containing layers, in the case of homoepi- rate growth of SiC at low temperatures ", Journal of Applied Physics 104, 053517 (2008). In "Prevention of In-droplet formation by HCl addition during metal vapor phase epitaxy of InN", Applied Physics Letters 90, 161126 (2007) ", the authors describe the effect of Cl, particularly in the form of HCl in a crystal deposition process, in which process gases NH3 and TMIn is used.

The invention has for its object to provide measures by which a parasitic occupancy of the susceptor upstream of the substrate is reduced. The object is achieved by the invention specified in the claims, wherein it is initially and essentially based on the gas inlet at least two separate inlet zones, wherein a halogen component inlet zone, which is connected to the halogen component source, in such adjacent and upstream of one Heated surface portion of the process chamber is arranged that where there is no introduction of a halogen component parasitic growth, this growth is at least reduced, preferably completely suppressed at least on a portion of the surface portion. If necessary, that can Inlet member having a cooling device and at least two, preferably three separate gas inlet zones, wherein between a connected to the source of the V or VI component, preferably the hydride source connected to V or VI inlet zone and one connected to the halogen component source Halogenkomponenteneinlasszone additionally a separation gas inlet zone is arranged, which is not connected to the source of the V or VI component, preferably the hydride source still with the halogen component source or is connectable to one of these sources during a halogen component feed into the process chamber. It is further provided that the separation gas inlet zones is connected or connectable to the source of the organometallic component. The device then has a total of at least three separate gas inlet zones, wherein only one of the three gas components is possibly introduced together with a carrier gas into the process chamber through each of the three inlet zones. However, the halogen component can also be introduced at a different location in the process chamber, for example, in recesses of the susceptor substrate holder einhegen, which are supported on a gas cushion driven in rotation by a gas stream. This gas stream, the halogen component can be mixed. The susceptor may also support a bottom plate, which is arranged in front of the substrate holders in the flow direction and in which openings are arranged, from which a gas containing HCl can emerge. The gas inlet member is cooled by a cooling device to an inlet temperature which is below the decomposition temperature of the process gases. In a device which is preferably flowed through in the horizontal direction, the process gas enters the process chamber through gas inlet zones arranged vertically one above the other. The process gas passes in the horizontal direction a flow zone within which the process gases can mix. Since the hydride and the halogen component are vertically spaced apart at different levels in the process chamber are introduced, meet halogen component and hydride only at a horizontal distance downstream of the inlet zone within the flow zone to each other. Since the halogen component flows separately from the other prosyst gases directly above the susceptor, ie in the lowermost gas layer into the process chamber, the halogen component concentration in the lowermost gas layer immediately above the susceptor is highest. The halogen component thus develops a somewhat corrosive effect in the flow zone. It is also conceivable that metal halide components or compounds of the decomposition products of the organometallic component with the halogen component, which are volatile, form within the gas phase above the susceptor. As it flows through the flow zone, the hydride and the halogen component diffuse toward one another. At the point of contact, the gases have already been heated in such a way that the gas temperature is above a reaction temperature at which the hydride and the halogen component react with one another to form a solid. The location at which the halogen component and the hydride first come into contact with each other is alternatively or even within an adduct formation zone, ie in a region of the process chamber in which the gas temperature lies within an adduct formation temperature range. Such adducts are formed, in particular, between ammonia and decomposition products of TMGa, TMA1 or TMIn. In a preferred embodiment of the device, the inlet zone for the V or VI component is located directly below the process chamber ceiling. The process chamber ceiling, like the susceptor, is thermally insulated from the cooled gas inlet member. The process chamber ceiling can be actively heated, to which the process chamber ceiling is assigned a separate heating device. But it is also possible that the process chamber ceiling is only passively heated. The susceptor is provided with a heater, such as a water-cooled RF coil heats and radiates heat that heats the process chamber ceiling. The gas inlet member may be located in the center of a rotationally symmetrical planetary reactor. The susceptor forms a plurality of circular disk-like substrate holders surrounding the gas inlet member, which support one or more substrates and which are rotated about their axis during growth. The gas inlet element fed from above lies in the center of the process chamber. It is ring-shaped surrounded by the susceptor, which can also be rotated. The susceptor has a multiplicity of depressions, wherein in each depression a substrate holder rests, which is rotated resting on a gas cushion. The rotary drive is formed by a directed gas flow. One or more substrates may rest on the substrate holder. During layer growth, the process gas from the gas inlet member enters the flow zone in the radial direction, the halogen component being introduced into the process chamber at the lowest level, so that the heated susceptor surface located immediately downstream of the halogen component inlet zone has a relatively large halogen component. Concentration is applied. While in the absence of the halogen component, the precursor zone of the susceptor is coated with decomposition products of the process gases, in particular decomposition products of TMGa, TMA1 or TMIn, this parasitic growth is reduced by targeted introduction of the halogen component in the surface area of the particular ring-shaped precursor zone. The halogen component is preferably a hydrogen halide component and especially HCl. But it can also be a gaseous halogen, for example Cl ₂ . The V component is preferably ammonia, arsine or phosphine. The process according to the invention is carried out in the case of such process parameters, ie partial gas pressures of the process gases, such susceptor temperature, total gas flow and total pressure in which, without feed-in Halogen component parasitic growth takes place on a heated surface portion of the flow zone of the process chamber upstream of the substrate and on which the halogen component feed suppresses the parasitic growth. The introduction of the halogen component, in particular of HCl, is greater to suppress the parasitic growth upstream of the substrates than is required to suppress parasitic nucleation processes in the gas phase. For example, the molar rate of the halogen component fed into the process chamber to the III component can be up to 70%. Higher molar ratios are also possible, for example the molar ratio between HCl flow and TMGa flow can be up to 1: 1 or even up to 2: 1. In the latter parameter sets, HCl is offered in excess. In order to suppress an undesirable interaction of the halogen component with the V component, a high separation gas flow is fed between the V component inlet zone and the halogen component inlet zone. Alternatively or in combination, however, the separation gas inlet zone can also have a greater height, so that the HCl diffusion to the hydride is reduced.

The invention will be explained with reference to the accompanying drawings. Show it:

Fig. V. Schematically a sectional view of a process chamber arranged in a reactor housing, not shown, which is flowed through in the horizontal direction of the process gas together with a gas mixing / supply device, in which only the

Explanation of the invention are shown essential elements 2: the temperature profile in the flow direction at three different positions in the process chamber,

3 shows a solid line schematically the course of the growth rate over the flow direction without HCl feed and as a dashed line with HCl feed,

4 shows a plan view of a susceptor of a horizontal chamber reactor with a centric gas inlet element, wherein the flow zone V is indicated by a dashed line and a zone C by a dot-dash line between the dashed line, in which a parasitic occupancy takes place,

5: the influence of the HCl feed or the molar flow ratio to TMGa flow on the reduction of the size of the zone in which a parasitic occupancy takes place and

Fig. 6: the growth rate on the substrate as a function of the distance to the gas inlet member.

The gas mixing / supply device 34 shown in FIG. 1 has a hydride source 30, which in the exemplary embodiment is an ammonia source. It also has a source of an organometallic component 31, which in the exemplary embodiment is trimethylgallium. Furthermore, a halogen component source 32 of a halogen component is provided, which in the exemplary embodiment is HCl. Finally, the gas mixing / supply device 34 also has a carrier gas source 33, wherein the carrier gas is hydrogen. The sources 30, 31, 32, 33 are shown as gas tanks. It may be a gas cylinder or a bubbler. Each gas source 30, 31, 32 is connected to a gas outlet, which can be closed by a valve 26, 27, 28, 29, which valves 26, 27, 28, 29 can be switched by a control device, not shown. Downstream of the valves 26, 27, 28, 29 are mass flow regulators 22, 23, 24, 25, with which a carrier gas stream or a stream of the hydride, the organometallic component or the halogen component is adjustable. The mass flow controller 24 regulates a halogen component gas stream which is diluted with the carrier gas stream and which is fed through a halogen component feed line 21 to a halogen component inlet zone 10 of a gas inlet element 7. With the mass flow controller 23, the mass flow of an organometallic component, which can be promoted for example with a carrier gas from a bubbler, regulated. With a mass flow controller 25, this gas stream is diluted and replaced by a MO

Feed line 20 passed to a MO inlet zone 9. The MO inlet zone 9 forms a separation gas inlet zone.

The mass flow controller 22 regulates the mass flow of the hydride, which can also be diluted with a carrier gas flow and which is fed through the hydride feed line 19 to a hydride inlet zone 8.

The MO feed line 20 upstream of the MO inlet zone 9 is provided with valves 27 and mass flow controllers 23 such that it is not possible to introduce a halogen component from the halogen component source 32 or 32 during the feeding of the halogen component through the halogen component inlet zone 10 to pass a hydride from the hydride source 30 through the MO inlet zone 9. The hydride inlet zone 8 and the halogen Component inlet zone 10 upstream hydride supply line 19 and halogen component supply line 21 are designed so that neither the source derived from the hydride 30 nor the source 32 stemmende halogen component can enter the separation gas inlet zone 9, so that only a separation gas can flow through the separation gas inlet zone 9, in which it is an inert gas, namely the carrier gas and the MO component.

The said gas inlet zones 8, 9, 10 are associated with a gas inlet member and, as is generally known from DE 10 2004 009 130 AI, arranged vertically one above the other. The gas inlet member 7 is cooled. It has partitions 12, 13, an upper wall 14 and a lower wall, in which a cooling liquid channel 11 is shown. Preferably, all partitions 12, 13, 14 are liquid-cooled and have this cooling liquid channels. The gas inlet member 7 forms the gas inlet zone E. By means of cooling water, the gas inlet member 7 can be maintained at temperatures in the range below 250 ° C or 300 ° C.

In a horizontal extent, the process chamber 1, whose bottom is formed by a susceptor 2 and whose ceiling 6 runs parallel to the susceptor 2, is adjoined by the gas inlet zones 8, 9, 10 lying vertically one above the other. The three gas inlet zones 8, 9, 10 arranged one above the other extend over the entire height of the process chamber 1, with the halogen component inlet zone 10 directly adjoining the bottom of the process chamber and the hydride inlet zone 8 directly adjoining the ceiling 6 of the process chamber 1 and the separation gas inlet zone 9 is interposed. The individual superimposed gas inlet zones 8, 9, 10 may have identical heights. But it is also envisaged that the gas inlet zones 8, 9, 10 have different heights. At a process chamber height of about 20 mm, the heights of the hydride inlet zone 8, the separation gas inlet zone 9 and the halogen component inlet zone 10 may have the height ratio 1: 2: 1. In one variant, the height ratio 1: 3: 1 is provided. In the direction of flow, a feed zone V connects to the inlet zone E. The flow zone V extends over a heated wall portion 15 of the susceptor 2. The heating of the susceptor 2 via an RF heater 18 in the form of a water-cooled induction coil, which is arranged below the susceptor 2. In the susceptor 2 produced from graphite or another conductive material, eddy currents are thereby produced, which leads to a heating of the susceptor 2. Depending on the process step, the susceptor 2 is heated to different temperatures, for example for depositing a seed layer GaN / AlN at 550 ° C., an n-GaN layer at 1050 ° C. and AlGaN layers, a p-type GaN layer at 900 ° C, an InGaN layer at 750 ° C of an AlGaN layer at 1050 ° C and layers for optoelectronic applications up to 1400 ° C. The susceptor 2 opposite ceiling wall 6 has a lower by about 200 ° C temperature.

Downstream of the flow zone V extends the growth zone G, in which one or more substrate holders 3 are arranged. In the sectional view of Figure 1, only a circular disk-shaped substrate holder 3 is shown, which rests in a recess 5 of the susceptor 2 and which is rotated on a gas cushion during the implementation of the method. On the substrate holder 3 there is a substrate 4 to be coated whose substrate temperature T _s can be regulated to a value typically between 900 and 1100 ° C. The hot susceptor 2 heats the process chamber 1 to a temperature T _c . In the middle of the process chamber 1, a gas temperature TB sets in, which is between the process chamber ceiling temperature T _c and the substrate temperature T _s .

The growth zone G is adjoined by an outlet zone A, in which a gas outlet device 16 is arranged, which is connected to a vacuum pump 17, so that the total gas pressure within the process chamber can be set to values between a few millibars and atmospheric pressure.

The process chamber shown schematically in FIG. 1 has a circular susceptor 2, which concentrically surrounds the likewise gas-symmetrical gas inlet member 7.

The vertical spacing of the partitions 12, 13, which defines the height of the MO inlet zone 9, is chosen such that the diffusion boundary layer D shown in dashed lines in FIG. 1 is formed. The diffusion boundary layer D symbolizes the boundary up to which halogen components introduced from the halogen component inlet zone 10 in the upstream zone to the hydrofluid flow and introduced through the hydride inlet zone 8 diffuse downwards in the direction of the halogen component. The hydrides or halogen components thereby diffuse into a separation gas flow which enters the process chamber through the separation gas inlet zone 9. The inlet zone 9 located between the hydride inlet zone 8 and the halogen component inlet zone 10 therefore forms a separating gas inlet zone through which, together with a carrier gas, the organometallic component is also introduced into the process chamber.

The upper and lower diffusion boundary layers D, which are only shown qualitatively, meet at the beginning of a region M of the lead zone V in which the gas temperature TB has reached a value above 338 ° C. at atmospheric pressure, at which NH 3 and HCl no longer react to form a ammonium chloride powder. At reduced total pressure in the process chamber, this gas temperature drops to, for example, 220 ° C at 10 mbar.

FIG. 2 schematically shows the profile of the temperature T _{s of} the susceptor, the temperature TB of the gas approximately in the vertical center of the process chamber, and the temperature T _{c of} the process chamber ceiling, in each case along the flow direction of the process gas. It can be seen that in the region of the preliminary zone V, the gas temperature has the lowest values. Thus, a cold finger forms approximately in the middle of the flow zone. At the end of the cold finger, where the halogen component comes into contact with the hydride, adducts are formed in the absence of the halogen component, inter alia, with the use of ammonia and TMGa. These form the nucleation nuclei for particles, which, in the absence of the halogen component, bind a large number of the ΠΙ-metal atoms, which are thus removed from the layer growth. The spatially separate inlet of the halogen component of the hydride leads process technology to an injection of the halogen component in an adduct formation volume, which lies in the zone M. This adduct formation volume is doped with the halogen component, it being sufficient if a maximum of 250 ppm of the total amount of gas HCl or the HCl flow in the process chamber is below 10% of the MO gas flow.

It can be seen from FIG. 2 that the temperature T _{s of} the susceptor 2 increases linearly in the region of the flow zone V and then proceeds substantially constantly in the region of the growth zone G and decreases again in the region of the outlet zone. The temperature T _{c of} the radiant-heated reactor ceiling 6 also increases continuously in the region of the flow zone V and runs in the Area of the growth zone G constant, and then drop off again in the region of the outlet zone A. The gas temperature TB has substantially the same course as the temperatures T _s and T _c . However, it rises more steeply in the flow zone V than the temperature T _{c of} the process chamber ceiling 6. It exceeds only in the zone M the temperature T _{c of} the process chamber ceiling.

FIG. 3 qualitatively shows the progression of the growth rate in the direction of flow as a solid line without HCl feed and as a dashed line with HCl feed, the course of the growth rate curve substantially corresponds to the profile of the partial pressure of the metal of the II or III component in the gas phase. It can be seen that without HCl feed, the maximum of the growth rate r is in the feed zone V, immediately upstream of the growth zone G, ie in the gas mixing zone M. Without HCl feed, the growth rate r or the depletion curve of the Metal component in the growth zone G non-linear, so that it comes to inhomogeneous growth on the rotated during the deposition process substrates. The edge regions of the substrates have a higher layer thickness than the center of the substrates. As a result of the halogen component feed directly above the hot wall section 15 of the susceptor 2 there prevails at the surface a relatively high halogen component concentration. The halogen component, for example HCl, can develop there a surface-etching effect, so that in the hot flow zone 15 parasitic growth can be suppressed. The maximum of the growth rate shifts towards the downstream. At the same time the depletion curve is linear. The latter can be attributed in particular to the reduced adduct formation due to the HCl feed. By introducing small amounts of a halogen component, for example HCl into the adduct formation zone, the reactor can be operated with relatively low gas flows, so that the mean residence time of the process gas within the process chamber 1 is greater than 1.5 seconds. However, the length of the growth zone G in the flow direction may be more than 150 mm. Within this length of the growth zone G, the gas phase depletion decreases in particular III component linearly, so that 4 layers with a homogeneous layer thickness can be deposited by rotating the substrate.

Due to the reduction of particle formation, the growth rate downstream of the flow zone V is also increased at the same time. The effect according to the invention of HCl already occurs at very low partial pressures of the halogen component, ie in process parameter sets in which the halogen component has no influence on the adduct formation. At such low HC1 partial pressures, the HCl feed has no influence on the course of the depletion curve in the growth zone.

In the first experiments gallium nitrite was deposited at a substrate temperature Ts of 1050 ° C and at a process chamber ceiling temperature T _c of 900 ° C at a respective same hydrogen carrier gas amount. This was done at residence times of 0.58 seconds, 1.01 seconds and 1.52 seconds. Radial depletion was measured by growth rates on a 4-inch sapphire substrate. Without the addition of HCl, the depletion curve is very inhomogeneous with high residence times and drops below one third even in the middle of the growth zone G. Due to the addition of only 2 sccm HCl, the depletion curves are essentially congruent for all three residence times. It has been found that by molar ratio of 2% HCl / TMGa is sufficient to linearize the depletion curve. Optimum results are achieved when the molar ratio between HCl and TMGa is approximately in the range of 5% to 7%. In second experiments, aluminum nitrite was deposited instead of gallium nitrite. The III component used was TMAl. TMAl is far more reactive to NH3 than TMGa. In addition, the adducts are considered very stable. Aluminum nitrite was also deposited here on 4-inch sapphire substrates, but at a substrate temperature of 1200 ° C at a process chamber ceiling temperature of about 1100 ° C and each hydrogen carrier gas amount. The residence times of the process gases within the process chamber were 0.08 seconds and 0.33 seconds, respectively. Again, without the addition of HCl, a significant dip in the depletion curve was observed for the long residence time. The addition of HCl also led to a linearization of the depletion curve with longer growth times.

In a variant in which the height of the hydride inlet zone is 5 mm, the separating gas inlet zone 9 is 10 mm and the halogen component inlet zone 10 is 5 mm, 16.6 slm NH3 are produced through the upper gas inlet zone 8 and 31 31 slm H through the central gas inlet zone ₂ + 6 slm N ₂ and fed through the lower gas inlet zone 10 16.8 slm H ₂ . For reasons of flow stability, the gas flow distribution is roughly oriented to the height distribution of the gas inlet zones 8, 9, 10, so that the gas velocity from the inlet level to the inlet level remains approximately the same. The maximum mismatch of the gas velocities, the pulse current densities (rho * v) or the Reynolds numbers (rho * v * H / μ) can be for example 1: 1.5 or 1: 2 or 1: 3. In addition, HCl is fed through the lower gas inlet zone 10, wherein the HCl flow corresponds to a maximum of about one tenth of the flow of the pure organometallic component, the is additionally fed through the central inlet zone 9. In a scale

U ^■ H ² tion of the process chamber is taken to ensure that the index remains constant, where U is the average gas velocity in all three inlet levels at the same pressure, H is the height of the central inlet, R is the radius of the gas inlet member 7 and D is the diffusion coefficient of the process gas in the gas mixture. This results in the following application examples: if the height H of the central inlet is doubled, then the gas velocities can be quartered. If the diameter of the gas inlet member 7 is doubled, the height H of the central inlet must be increased by a factor of 1.4. Alternatively, the flow rates can be quadrupled.

It is also envisaged to feed the halogen component, in particular HCl, together with the organometallic component through a common gas inlet zone into the process chamber. Furthermore, the metal-organic component mixed with the hydride can also be fed into the process chamber through a common gas inlet zone.

The process chamber may have a diameter of 365 mm and a height of 20 mm. The height of the inlet zones 8, 9, 10 is on average 10 mm or obeys the above scaling rule. The inlet zone E extends to a radius of about 22 mm. The flow zone runs in a radial range between 22 mm and 75 mm. The growth zone G extends in a radial range between 75 and 175 mm. Radially outside the growth zone G is the outlet zone A. The total gas flow through the process chamber is between 70 and 90 slm. The growth processes are carried out in a pressure range between 50 and 900 mbar. At a total pressure of, for example, 400 mbar, the ammonia partial pressure 95 mbar, the TMGa Partial pressure 0.073 mbar to 0.76 mbar correspond. Without the addition of HCl, the growth rate saturates at a TMGa partial pressure of about 0.255 mbar. With the addition of HCl, the growth rate can be increased to values above 10 μιη / h. With a 5% molar ratio of HCl: TMGa were at a TMGa partial pressure of 0.35 mbar 13.8 μιη / h and at a TMGa partial pressure of 0.76 mbar 26.5 μιη / h achieved as a growth rate.

Among other things, the following parameter sets lead to improved results compared to the prior art in a 10 × 2 configuration:

Total pressure = 600 mbar, p (NH3) = 142.5 mbar, TMGa partial pressures of 0.04 mbar to 0.82 mbar (corresponding to 2.13E-4 to 4.3E-3 mol / min).

Total pressure = 800 bar, p (NH3) = 190 mbar, TMGa partial pressures of 0.054 mbar to 1.09 mbar (corresponding to 2.13E-4 to 4.3E-3 mol / min).

Total pressure = 900 mbar, p (NH3) = 214 mbar, TMGa partial pressures of 0.06 mbar to 1.23 mbar (corresponding to 2.13E-4 to 4.3E-3 mol / min). FIG. 4 shows the top view of the susceptor, in which a plurality of substrate holders 3 are arranged at the same radial distance around a gas inlet element 7 arranged at the center at a distance V, on each of which a substrate lies. C is an occupancy zone which has a dependent on the amount of HCl fed radial width. In experiments in which gallium nitrite was deposited, the susceptor was heated to 1080 ° C and the process chamber ceiling to 830 ° C. The measured surface temperature on the substrates was 1,065 ° C. At a total pressure within the process chamber of 400 mbar, the gas inlet ensure a total gas flow of 82 slm (standard liters per minute) initiated. It contained a TMGa flow of about 0.6 mmol / min. The molar ratio between the V component and the III component was 1244. As a result, the NH3-FIUSS was 16.6 slm. At a growth rate of 2 μιη / h, a layer was deposited on the substrate over a total time of two hours. The experiments were carried out without HCl feed and with different levels of HCl feeds. The higher the amount of HCl fed in, the smaller the width of the zone denoted C in FIG. 4 in which parasitic growth takes place on the surface of the susceptor 2. With a width of the lead zone V of 7.5 cm, the width of the zone C without HCl feed was about 50 mm. When feeding 1 sccm (standard cubic centimeter per minute) of HCl, the zone width C was reduced to 4.5 cm, at 3 sccm to 3 cm and at 9 sccm to 1 cm. Based on the illustration according to FIG. 4, the dot-dash line approaches the dashed line with increasing HCl flow.

FIG. 5 shows the effect of the HCl feed on the radial width of the section of the feed zone, which is occupied during the deposition process with parasitic growth. The approximately 75 mm wide zone without HCl feed becomes narrower with increasing HCl feed. Their width is reduced by more than half.

FIG. 6 shows the layer thickness measured geometrically over a substrate, which did not rotate during the deposition. As a result of gas phase depletion, the growth rate decreases with increasing distance from the gas inlet member. In all four experiments, the decline in growth rates is linear. It can thus be compensated by a rotation of the substrate holder. Only curve d, which leads to the experiment with the highest HCl Supply corresponds, shows a growth-reducing effect of HCl.

All disclosed features are essential to the invention. The disclosure of the associated / attached priority documents (copy of the prior application) is hereby also incorporated in full in the disclosure of the application, also for the purpose of including features of these documents in claims of the present application. The subclaims characterize in their optional sibling version independent inventive development of the prior art, in particular to make on the basis of these claims divisional applications

LIST OF REFERENCE NUMBERS

1 process chamber 27 valve - MO

2 susceptor 28 valve - halogen component

3 substrate holder 29 valve - carrier gas

4 Substrate 30 Source - hydride

5 recess 31 Source - MO

6 Process chamber ceiling 32 Source - halogen component

7 Gas inlet element 33 Source - carrier gas

8 Hydrideinlasszone 34 Gasmisch / - Versorgungs¬

9 Separating gas inlet zone (MO) device

10 halogen component inlet zone E inlet zone

11 Coolant channel V Flow zone

12 Partition G Growth zone

13 Partition A outlet zone

14 upper wall D diffusion boundary layer

15 wall section M mixing zone

16 outlet device

17 vacuum pump

18 RF heating

19 hydride supply line

20 MO supply line

21 Halogen component feed

22 MFC hydride

23 MFC MO

24 MFC halogen component

25 MFC carrier gas

26 valve hydride

Claims

1. Device for depositing II-VI or III-V semiconductor layers on one or more substrates (4), with a reactor housing having a process chamber arranged in the reactor housing (1), one in the process chamber (1) arranged in the horizontal direction extending susceptor (2) for receiving the substrate (4), a heater (18) for heating the susceptor (2) to a susceptor temperature (T _s ), a gas inlet member (7) which is the process chamber (1) associated with, if necessary together with a carrier gas in each case to introduce process gases in the form of a V or VI component, in particular a hydride, an organometallic II or III component and a halogen component into the process chamber (1), and a gas outlet device (16) for exit of reaction products and optionally of the carrier gas from the process chamber (1), having a gas mixing / supply device (34) comprising a source (31) for the organometallic component, a source (30) for the V or VI component, in particular for the hydride, and a source (32) for the halogen component, said sources (30, 31, 32) via delivery lines (19, 20, 21) coming from a Control means controlled valves (26, 27, 28) and mass flow controllers (22, 23, 24) are connected to the gas inlet member (7) to the organometallic component, the V or VI component, in particular the hydride and the Halogen component in separate gas flows, if necessary together with the carrier gas, into the heated process chamber (1), the gas inlet member (7) having a plurality of separate gas inlet zones (8, 9, 10), wherein a halogen component inlet zone (10), which is connected to the halogen component source (32) upstream of a surface portion (15) of the process chamber, characterized in that the halogen component inlet zone (10) is one in the flow zone (V) lying surface portion (15) of the susceptor (2) closest to the gas inlet zone.

2. Device according to claim 1 or in particular according thereto, characterized in that the gas inlet zones (8, 9, 10) are arranged vertically one above the other, wherein the lowermost Halogenkomponenteneinlasszone (10) the susceptor (2) is closest.

3. Device according to one or more of the preceding claims or in particular according thereto, characterized in that one with the source

(31) the organometallic component conduction-connected MO inlet zone (9) lies above the halogen component inlet zone (10) and a V inlet zone (8) connected to the source (30) of the V or VI component is closest to the process chamber ceiling (6) ,

4. Device according to one or more of the preceding claims or in particular according thereto, characterized in that the gas inlet member (7) has a cooling device (11) with which it can be cooled to an inlet temperature which is below the decomposition temperature of the process gases.

5. Device according to one or more of the preceding claims, characterized by a parallel to the susceptor (2) extending process chamber ceiling.

6. A method for depositing II-VI or III-V layers on one or more substrates (4), in particular in a device according to one of the preceding claims, wherein process gases in the form of an organometallic II or III component, a V or VI component, in particular a hydride and a halogen component are provided in a gas mixing / supply device (34), the at least one substrate (4) being applied to a susceptor (2) in a process chamber (1), the susceptor (2) and at least one process chamber wall (6) to a Suszeptortem- temperature (T _s ) or wall temperature (T _c ) are heated, the process gases are optionally introduced together with a carrier gas in separate gas flows by means of a gas inlet member (9) in the process chamber (1), where the organometallic component and the V or VI component, in particular the hydride, react pyrolytically on the substrate surface so as to deposit a layer on the substrate (4) and the halogen component reduces or suppresses parasitic particle formation in the gas phase and reaction products optionally together with the carrier gas through a gas outlet device (16) leave the process chamber, characterized in that the di Process gases are introduced into the process chamber through at least two separate gas inlet zones (8, 9, 10), one of which is a halogen component inlet zone (10), through which upstream immediately upstream of a heated surface section (15) of the susceptor (2). the halogen component is introduced into the process chamber (1).

7. The method according to claim 6 or in particular according thereto, characterized in that the method is at such process parameters, ie such partial gas pressures of the V or VI component and the II or III component, such Suszeptortemperatur (T _s ), such total gas flow and Such total pressure is carried out, in which without feeding a halogen component parasitic growth on the heated surface portion (15) of the flow zone (V) of the process chamber (1) upstream of the substrate (4) takes place and the feed of the halogen component, the parasitic growth is reduced or suppressed.

8. The method according to one or more of claims 6 or 7 or in particular according thereto, characterized in that the halogen component, which is preferably hydrogen chloride, immediately above the extending in the horizontal direction of the susceptor (2) is introduced into the process chamber (1).

9. The method according to one or more of claims 6 to 8 or in particular according thereto, characterized in that the parasitic growth reducing or suppressing effect of the halogen component substantially to an upstream of the growth zone (G), in which the substrate (4) is arranged , lying flow zones (V) is limited.

10. The method according to one or more of claims 6 to 9 or in particular according thereto, characterized in that the halogen component is introduced in such a spatially separated from the hydride in the process chamber (1) that the halogen component occurs only in a flow section in contact with the hydride, in which the growth rate or the decomposition rate of the organometallic component has its maximum.

11. The method according to one or more of claims 6 to 10 or in particular according thereto, characterized in that the method in such process parameters, ie such partial gas pressures of the V or VI component and the II or III component, such Suszeptortemperatur ( T _s ), such total gas flow and total pressure is carried out in which without feeding a halogen component parasitic growth on the heated Surface portion (15) of the flow zone (V) of the process chamber (1) takes place upstream of the substrate (4).

12. The method according to one or more of claims 6 to 11 or in particular according thereto, characterized in that the ratio of the molar flow of the halogen component in the process chamber to the molar flow of the II or III component in the process chamber up to 1: 2, up to 7:10, up to 1: 1 or up to 2: 1.