DE102011002146A1 - Apparatus and method for depositing semiconductor layers with HCI addition to suppress parasitic growth - Google Patents

Abstract

The invention relates to a device and a method for depositing II-VI or III-V semiconductor layers on one or more substrates (4), with a reactor housing having a process chamber (1) arranged in the reactor housing, one in the process chamber (1) arranged susceptor (2) for receiving the substrate (4), a heating device (18) for heating up the susceptor (2), a gas inlet element (7) with a gas mixing / supply device (34) having a source (31) for the organometallic component, a source (30) for a hydride, and a source (32) for the halogen component, the sources (30, 31, 32) being connected to the gas inlet element (7) in order to feed the gases in separate gas flows into the heated process chamber (1) bring. To reduce parasitic occupancy of the susceptor upstream of the substrate, it is proposed that the gas inlet element (7) have several separate gas inlet zones (8, 9, 10), one halogen component inlet zone (10) which is connected to the halogen component source (32), is arranged upstream directly in front of a heated surface section (15) of the process chamber.

Description

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 susceptor temperature, a gas inlet member, which is associated with the process chamber, optionally together with 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 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 for the halogen component ente, wherein the sources via delivery lines, and controllable by a controller 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, wherein in successive process steps by means of the control valves and the mass flow controller controlling process gases are fed in a different composition 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 in a gas mixing / supply device are provided, 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 separate 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 a parasitic particle formation in the gas phase is reduced or suppressed and the carrier gas leaves the process chamber together with reaction products through a gas outlet device, wherein process gases are fed into the process chamber in mutually different composition in successive process steps by means of a controlling the valves and the mass flow controller control device.

A generic device or a generic method describes the US 7,585,769 B2 , There, a device or a method for depositing III-V semiconductor layers on a substrate in a reactor housing is described there. 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.

The US 4,961,399 A describes a device for depositing III-V layers on a plurality of substrates arranged around a center of a rotationally symmetric process chamber. A gas inlet element is arranged in the center of the process chamber and serves to introduce a hydride, for example NH ₃ , AsH ₃ or PH ₃ . In addition, organometallic compounds, which may be, for example, TMGa, TMIn or TMAl, 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 located below the susceptor is in the DE 102 47 921 A1 described. In such a CVD reactor, the process chamber extends in the horizontal direction, is bounded below by a susceptor and at the top by a ceiling plate.

The DE 10 2004 009 130 A1 describes a MOCVD reactor with a symmetrically arranged around a central gas inlet member process chamber. 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 at an inlet temperature that is at room temperature or below 100 ° Celsius lies, introduced into the process chamber. 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, those are 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 towards 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, that is, the partial pressure of the III component is chosen so that the decomposition products are deposited crystal-forming on the substrate surface pyrolytically. The surface of the substrate is therefore also monocrystalline.

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

The DE 10 2004 009 130 A1 shows on the basis of the local 2 in that the growth rate within the growth zone decreases in the direction of flow. By means of suitable process management, a straight-line course of the decrease in the growth rate can be set. 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 via the gas flow from the process chamber without which contribute to the growth of the layer.

In "High growth rate process in a SiC horizontal CVD reactor using HCl", Microelectronic Engineering 83 (2006) 48-50 describe the effect of HCl on suppression of silicon nucleation.

In "Effect of HCl addition to gas phase and surface reactions during homoepitaxial growth of SiC at low temperatures", Journal of applied physics 104, 053517 (2008) The authors also describe the effect of additional HCl flux in depositing silicon containing layers.

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, especially in the form of HCl in one Crystal deposition process in which NH ₃ and TMIn are used as process gases.

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 set forth 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, so adjacent and upstream of a heated surface portion is arranged in the process chamber that, where takes place without introducing a halogen component parasitic growth, this growth is at least reduced, preferably completely suppressed at least on a portion of the surface portion. Optionally, the inlet member may comprise a cooling device and at least two, preferably three, separate gas inlet zones, with an additional inlet between a V or VI inlet zone connected to the source of the V or VI component, preferably the hydride source, and a halogen component inlet zone connected to the halogen component source Separating gas inlet zone is arranged, which is neither connected to the source of the V or VI component, preferably the hydride source nor 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 contemplated that the separation gas inlet zones are 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, substrate holders can lie in recesses of the susceptor, which are driven in rotation on a gas cushion by a gas flow. This gas stream, the halogen component can be mixed. The susceptor may also support a bottom plate which is disposed in front of the substrate holders in the flow direction and in which openings are arranged from which an HCl-containing gas can escape. 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 vertically arranged gas inlet zones. 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 introduced into the process chamber vertically spaced apart at different levels, the halogen component and hydride only meet one another at a horizontal distance downstream of the inlet zone within the flow zone. Since the halogen component flows separately from the remaining prosactic 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 form within the gas phase above the susceptor metal halide components or compounds of the decomposition products of the organometallic component with the halogen component, which are volatile. 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 is within an adduct formation temperature range. Such adducts form in particular between ammonia and decomposition products of TMGa, TMAl 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 heated with a heater, such as a water-cooled RF coil, thereby radiating 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 variety of Wells, wherein in each well 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 radially enters the flow zone, with the halogen component being introduced into the process chamber at the lowest level so that the heated susceptor surface immediately downstream of the halogen component inlet zone is exposed to a relatively high halogen component concentration. 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, TMAl or TMIn, this parasitic growth is reduced by targeted introduction of the halogen component in the surface area of the particular annular 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 at such process parameters, ie partial gas pressures of the process gases, such susceptor temperature, total gas flow and total pressure, in which parasitic growth takes place on a heated surface section of the flow zone of the process chamber upstream of the substrate without the introduction of a halogen component and on which the halogen component feed parasitic growth suppressed. The introduction of the halogen component, particularly 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 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:

1 : Schematically a sectional view of a process chamber arranged in a reactor housing, not shown, which is traversed in the horizontal direction by the process gas together with a gas mixing / supply device, in which only the essential elements for explaining the invention are shown,

2 : The temperature profile in the flow direction at three different positions in the process chamber,

3 FIG. 2: a solid line schematically showing the progression of the growth rate over the flow direction without HCl feed and as a dashed line with HCl feed,

4 FIG. 2: a top view of a susceptor of a horizontal chamber reactor with a central gas inlet element, wherein the lead 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 ratio to the TMGa flow on the reduction of the size of the zone in which a parasitic occupancy takes place and

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

The in the 1 illustrated gas mixing / supply facility 34 has a hydride source 30 in which it is an ammonia source in the embodiment. It also has a source of an organometallic component 31 which is trimethylgallium in the embodiment. Further, a halogen component source 32 a halogen component is provided, which is HCl in the embodiment. Finally, the gas mixing / supply facility has 34 also 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. Every gas source 30 . 31 . 32 is connected to a gas outlet, which has a valve 26 . 27 . 28 . 29 It can be closed, 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 controllers 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. With the mass flow controller 24 controlling a halogen component gas stream which is diluted with the carrier gas stream and which is passed through a halogen component feed line 21 one Halogen component inlet zone 10 a gas inlet organ 7 is forwarded. With the mass flow controller 23 is 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 through a MO supply line 20 to a MO inlet zone 9 directed. The MO inlet zone 9 forms a separation gas inlet zone.

With the mass flow controller 22 the mass flow of the hydride is controlled, which can also be diluted with a carrier gas flow and by the Hydriderzuleitung 19 a hydride inlet zone 8th is forwarded.

The MO inlet zone 9 in the flow direction upstream MO supply line 20 is so with valves 27 or mass flow controllers 23 provided that during the feeding of the halogen component through the halogen component inlet zone 10 is not possible, a halogen component from the halogen component source 32 or a hydride from the hydride source 30 through the MO inlet zone 9 through pass. The hydride inlet zone 8th and the halogen component inlet zone 10 upstream hydride supply line 19 and halogen component lead 21 are designed so that neither the source 30 originating hydride still that of the source 32 originating halogen component in the separation gas inlet zone 9 can enter, so that through the separation gas inlet zone 9 only a separation gas can flow, which is an inert gas, namely the carrier gas and the MO component.

The said gas inlet zones 8th . 9 . 10 are assigned to a gas inlet and are, as it is fundamentally from the DE 10 2004 009 130 A1 is known, arranged vertically one above the other. The gas inlet organ 7 is cooled. It has partitions 12 . 13 , an upper wall 14 and a bottom wall, at which a cooling liquid channel 11 is shown. Preference is given to all partitions 12 . 13 . 14 liquid cooled and have this cooling liquid channels. The gas inlet organ 7 forms the gas inlet zone E. By means of cooling water, the gas inlet member 7 be kept at temperatures in the range below 250 ° C or 300 ° C.

In the horizontal extension closes to the vertical floor-like superimposed gas inlet zones 8th . 9 . 10 the process chamber 1 whose bottom is from a susceptor 2 is formed and whose ceiling 6 parallel to the susceptor 2 runs. The three gas inlet zones arranged one above the other 8th . 9 . 10 extend over the entire height of the process chamber 1 wherein the halogen component inlet zone 10 directly to the bottom of the process chamber and the hydride inlet zone 8th directly to the ceiling 6 the process chamber 1 connects and the separation gas inlet zone 9 lies in between. The individual superimposed gas inlet zones 8th . 9 . 10 can have identical heights. But it is also envisaged that the gas inlet zones 8th . 9 . 10 have different heights. At a process chamber height of about 20 mm, the heights of the hydride inlet zone 8th , the separation gas inlet zone 9 and the halogen component inlet zone 10 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 section 15 of the susceptor 2 , The heating of the susceptor 2 takes place via an RF heating 18 in the form of a water-cooled induction coil, which is below the susceptor 2 is arranged. In the susceptor made of graphite or other conductive material 2 As a result, eddy currents are generated which lead to a heating of the susceptor 2 leads. The susceptor 2 Depending on the process step, it 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. InGaN layer at 750 ° C of an AlGaN layer at 1050 ° C and layers for opto-electronic applications up to 1400 ° C. The susceptor 2 opposite ceiling wall 6 has a temperature lower by about 200 ° C.

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 according to 1 is only a circular disk-shaped substrate holder 3 shown in a recess 5 of the susceptor 2 rests and which is resting on a gas cushion while performing the method. On the substrate holder 3 is a substrate to be coated 4 whose substrate temperature T _s can be controlled to a value typically between 900 to 1100 ° C. The hot susceptor 2 heats the process chamber 1 to a temperature T _c . In the middle of the process chamber 1 adjusts a gas temperature T _B , which is between the process chamber ceiling temperature T _c and the substrate temperature T _s .

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

The in the 1 schematically illustrated process chamber has a circular susceptor 2 , the concentric the likewise circularly symmetrical gas inlet organ 7 surrounds.

The vertical distance of the partitions 12 . 13 , which is the height of the MO inlet zone 9 Defined is chosen so that in the 1 Dotted lines shown diffusion boundary layer D forms. The diffusion boundary layer D symbolizes the boundary, up to that within the flow zone V halogen components from the halogen component inlet zone 10 towards the top of the hydride flow and through the hydride inlet zone 8th introduced hydrides diffuse down in the direction of the halogen component. The hydrides or halogen components diffuse into a separation gas flow through the separation gas inlet zone 9 enters the process chamber. The between the hydride inlet zone 8th and the halogen component inlet zone 10 located inlet zone 9 therefore forms a separation gas inlet zone through which, together with a carrier gas and the organometallic component is introduced into the process chamber.

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

The 2 schematically shows the profile of the temperature T _{s of} the susceptor, the temperature T _{B of} the gas approximately in the vertical center of the process chamber and the temperature T _{c of} the process chamber ceiling respectively along the flow direction of the process gas. It can be seen that in the region of the feed 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 III metal atoms, which are thus removed from the layer growth. The spatially separate inlet of the halogen component of the hydride leads processically to an injection of the halogen component in an adduct formation volume, which is 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.

Of the 2 it can be seen that the temperature T _{s of} the susceptor 2 increases linearly in the region of the flow zone V and then in the region of the growth zone G is substantially constant 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 region of the growth zone G constant, and then drop off again in the region of the outlet zone A. The gas temperature T _B has substantially qualitatively the same course as the temperatures T _s and T _c . However, it rises steeper in the flow zone V than the temperature T _{c of} the process chamber ceiling 6 , It only exceeds the temperature T _{c of} the process chamber ceiling in zone M.

Of the 3 is qualitatively the course of the growth rate in the flow direction as a solid line without HCl feed and as a dashed line with HCl feed to take, the course of the growth rate curve corresponds substantially to the course 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 flow 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 just above the hot wall section 15 of the susceptor 2 There prevails a relatively high halogen component concentration on the surface. 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 by the Ha 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 by rotating the substrate 4 Layers are deposited with a homogeneous layer thickness.

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 of HCl according to the invention 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 HCl 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 T _s of 1050 ° C. and at a process chamber ceiling temperature T _c of 900 ° C. with the same hydrogen carrier gas quantity in each case. 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 at a 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 TMA1. TMA1 is far more reactive to NH ₃ 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 at longer growth times.

In a variant in which the height of the hydride inlet zone is 5 mm, the separation gas inlet zone 9 10 mm and the halogen component inlet zone 10 is 5 mm, through the upper gas inlet zone 8 16.6 slm NH ₃ , through the middle gas inlet zone 9 31 slm H ₂ + 6 slm N ₂ and through the lower gas inlet zone 10 16.8 slm H ₂ fed. For reasons of flow stability, the gas flow distribution is roughly oriented to the height distribution of the gas inlet zones 8th . 9 . 10 so that the gas velocity from inlet level to 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. Through the lower gas inlet zone 10 In addition, HCl is fed, the HCl flow corresponds to about a maximum of one-tenth of the flow of the pure organometallic component, in addition through the central inlet zone 9 is fed. When scaling the process chamber, care is taken to ensure that the code U · H² / D · R remains constant, where U is the mean gas velocity in all three inlet planes at the same pressure, H the height of the middle inlet, R the radius of the gas inlet organ 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. Will the diameter of the gas inlet organ 7 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 organometallic component can be mixed with the hydride fed through a common gas inlet zone in the process chamber.

The process chamber may have a diameter of 365 mm and a height of 20 mm. The height of the inlet zones 8th . 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 may correspond to 95 mbar, the TMGa partial pressure may correspond to 0.073 mbar to 0.76 mbar. 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 μm / h. With a 5% molar ratio of HCl: TMGa, at a TMGa partial pressure of 0.35 mbar, 13.8 μm / h and at a TMGa partial pressure of 0.35 mbar Partial pressure of 0.76 mbar 26.5 μm / 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).

The 4 shows the top view of the susceptor, in which around a gas inlet arranged in the center 7 at a distance V, a plurality of substrate holders 3 are arranged at the same radial distance, on each of which a substrate is located. 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 introduced a total gas flow of 82 slm (standard liters per minute). This included 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 NH ₃ flow was 16.6 slm. At a growth rate of 2 μm / 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, the smaller the width of the 4 denoted by C in the parasitic growth on the surface of the susceptor 2 takes place. 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 4 the dotted line approaches the dashed line with increasing HCl flow.

The 5 shows the effect of the HCl feed on the radial width of the section of the flow 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.

The 6 shows the geometrically measured over a substrate layer thickness, which has not rotated 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 corresponds to the experiment with the highest HCl feed, shows a growth-decreasing effect of the 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

2

susceptor

3

substrate holder

4

substratum

5

recess

6

Process chamber ceiling

7

Gas inlet element

8th

Hydrideinlasszone

9

Separating gas inlet zone (MO)

10

Halogen component inlet zone

11

Coolant channel

12

partition wall

13

partition wall

14

upper wall

15

wall section

16

outlet

17

vacuum pump

18

RF heating

19

Hydridzuleitung

20

MO-supply

21

Halogen components supply

22

MFC hydride

23

MFC MO

24

MFC halogen component

25

MFC carrier gas

26

Valve hydride

27

Valve MO

28

Valve halogen component

29

Valve carrier gas

30

Source hydride

31

Source-MO

32

Source-halogen component

33

Source carrier gas

34

Gas mixing / -Versorgungseinrichtung

e

inlet zone

V

leading zone

G

growth zone

A

outlet zone

D

Diffusion boundary layer

M

mixing zone

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 7585769 B2 [0003]
• US 4961399 A [0004]
• DE 10247921 A1 [0004]
• DE 102004009130 A1 [0005, 0008, 0027]
• US 2008/0050889 [0007]

Cited non-patent literature

• "High growth rate process in a SiC horizontal CVD reactor using HCl", Microelectronic Engineering 83 (2006) 48-50 [0010]
• "Effect of HCl addition to gas phase and surface reactions during homoepitaxial growth of SiC at low temperatures", Journal of applied physics 104, 053517 (2008) [0011]
• "Prevention of In-droplet formation by HCl Addition During Metal Organic Vapor Phase Epitaxy of InN", Applied Physics Letters 90, 161126 (2007) [0012]

Claims (11)

Device for depositing II-VI or III-V semiconductor layers on one or more substrates ( 4 ), comprising a reactor housing having a process chamber arranged in the reactor housing ( 1 ), one in the process chamber ( 1 ) arranged susceptor ( 2 ) for receiving the substrate ( 4 ), a heating device ( 18 ) for heating the susceptor ( 2 ) to a susceptor temperature (T _s ), a gas inlet member ( 7 ), the process chamber ( 1 ) is assigned, if appropriate, 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 ( 1 ), and a gas outlet ( 16 ) for the exit of reaction products and possibly the carrier gas from the process chamber ( 1 ), with a gas mixing / supply device ( 34 ) having 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, the sources ( 30 . 31 . 32 ) via delivery lines ( 19 . 20 . 21 ), the valves controlled by a control device ( 26 . 27 . 28 ) and mass flow controllers ( 22 . 23 . 24 ), with the gas inlet member ( 7 ) are connected to the organometallic component, the V or VI component, in particular the hydride and the halogen component in separate gas flows optionally together with the carrier gas in the heated process chamber ( 1 ), characterized in that the gas inlet member ( 7 ) a plurality of separate gas inlet zones ( 8th . 9 . 10 ), wherein a halogen component inlet zone ( 10 ) with the halogen component source ( 32 ), upstream immediately upstream of a heated surface section ( 15 ) of the process chamber is arranged. Device according to claim 1 or in particular according thereto, characterized in that the susceptor ( 2 ) extends in the horizontal direction, the process chamber wall ( 6 ) one spaced and the susceptor ( 2 ) is parallel process chamber ceiling and the halogen component inlet zone ( 10 ) which are located in the flow zone (V) surface portion ( 15 ) of the susceptor ( 2 ) is the closest gas inlet zone. Device according to one of the preceding claims or in particular according thereto, characterized in that the gas inlet zones ( 8th . 9 . 10 ) are arranged vertically one above the other, wherein the lowermost halogen component inlet zone ( 10 ) the susceptor ( 2 ), one with the source ( 31 ) of the organometallic component of the line-connected MO inlet zone ( 9 ) above the halogen component inlet zone ( 10 ) and one with the source ( 30 ) of the V or VI component connected V inlet zone ( 8th ) of the process chamber ceiling ( 6 ) is closest. Device according to one or more of the preceding claims or in particular according thereto, characterized in that the gas inlet member ( 7 ) a cooling device ( 11 ), with which it is coolable to an inlet temperature that is below the decomposition temperature of the process gases. 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 in a gas mixing / supply device ( 34 ) comprising at least one substrate ( 4 ) to a susceptor ( 2 ) in a process chamber ( 1 ), the susceptor ( 2 ) and at least one process chamber wall ( 6 ) are heated to a susceptor temperature (T _s ) or wall temperature (T _c ), the process gases optionally together with a carrier gas in separate gas flows by means of a gas inlet member ( 9 ) into the process chamber ( 1 ) are introduced, where the organometallic component and the V or VI component, in particular the hydride, react pyrolytically with one another on the substrate surface, so that on the substrate ( 4 ) a layer is deposited, 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 process gases through at least two spatially separate gas inlet zones ( 8th . 9 . 10 ) are introduced into the process chamber, one of which is a halogen component inlet zone ( 10 ), through which immediately upstream of a heated surface section ( 15 ) of the process chamber ( 1 ) the halogen component in the process chamber ( 1 ) is initiated. The method of claim 5 or 6 or in particular according thereto, characterized in that the method is at such process parameters, ie such Partialgasdrucken the V or VI component and the II or III component, such Suszeptortemperatur (T _s ), such total gas flow and Such total pressure 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 by the supply of the halogen component, the parasitic growth is reduced or suppressed. Method according to one or more of claims 5 or 6 or in particular according thereto, characterized in that the halogen component, which is preferably hydrogen chloride, immediately above the horizontally extending susceptor ( 2 ) into the process chamber ( 1 ) is initiated. Method according to one or more of claims 5 to 7 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 ), lying flow zones (V) is limited. Method according to one or more of claims 5 to 8 or in particular according thereto, characterized in that the halogen component in such a spatially separated from the hydride in the process chamber ( 1 ) is introduced, that the halogen component 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. Method according to one or more of claims 5 to 9 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 Susceptor temperature (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. Method according to one or more of claims 5 to 10 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.

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