DE19851824C2 - CVD reactor - Google Patents

Description

The present invention relates to a CVD reactor.

A CVD reactor is known from EP 0 537 854 A1, in which the supply of the purge gas to the side of the gas dispersion device tion takes place so that the substrate and the substrate carrier are largely enclosed on the sides by the purge gas. By this encapsulation with purge gas is the reaction gas on the loading be delineated above the substrate, so that it can stay there longer. For this it is necessary that the Purging gas a corresponding back pressure to the incoming Re action gas. As a result of these printing conditions, it may however, in particular in the edge region of the substrate lungs come, the even processing of the sub prevent strats. In addition, a relatively large amount of purge gas is required Untitled.

Another CVD reactor is described in JP 06-136542 A. ben. There is a purge gas in the Pro above the substrate initiated zeßkammer. The purge gas is used there for fast Movement of the reaction gas to linger the reaction to suppress onsgases in the process chamber. This is supposed to the formation of granular silicon can be avoided otherwise could deposit on the reactor walls. to Ver requires rapid movement of the reaction gas drive according to JP 06-136542 A, however, a relatively large amount of purge gas. At the same time is due to the constant and heightened purging lens of the reaction gas with its increased consumption expected. The reaction gases are only incomplete uses. There is also a risk that as a result of the ho hen flow rate unwanted turbulence form.

DD 274 830 describes a CVD reactor with the purge gas is introduced laterally through chamber wall openings.  

In the manufacture of semiconductor devices Application of thin and conformal layers on semiconductors structured CVD (chemical vapor deposition) process puts. These methods have a number of advantages over other deposition processes. With CVD process Layers have a good edge condition, among other things on. In addition, such layers are relatively dense, d. H. they are without voids and with only a few defects len trained. The fast ones are technically favorable Processing, good stoichiometry control and a low cost-of-ownership of many CVD processes. Therefore, such ge CVD process, among other things for the production of semi-lead used building blocks, especially for rela tiv thin capacitor dielectrics.

Another is open for example in US 5,624,499 beard. The CVD reactor there comprises a process chamber, in a showerhead is arranged in the upper area is. This is used to distribute the reaction evenly gases within the process chamber. Opposite the showerhead in In the lower area of the process chamber is a substrate carrier seen. A semiconductor to be processed is placed on this substrate (wafer)  placed on and provided in the substrate carrier Vacuum suction fixed. Furthermore are in the substrate carrier Purge channels provided through the purge gas to the edge of the Substrate is performed. This measure serves to respond gases from the edges as well as from the back of the substrate remove. At the same time, the purging gases suck in of reaction gases prevented by the vacuum suction, so that no reaction gases can precipitate in this. Although there is a purge gas roller on the edge of the substrate Protective wall builds up around the substrate, becomes a mess cleaning of the substrate by falling off the chamber walls Particles not sufficiently suppressed. such Particles are, for example, the result of reaction gas deposits on the chamber walls. If this is not sufficient Dimensions removed or their formation is suppressed, it may be Particle dips in the CVD reactor occur as a result the substrate becomes contaminated.

It is therefore an object of the invention to provide a CVD reactor admit that the process is contaminated sufficient substrate is prevented.

According to the invention, this object is achieved by the subject of Claim 1 solved. Preferred further developments are counter stood the subclaims.

Since the reaction gases used are generally in the lower range sucked off the process chamber is in particular a rinse len the chamber walls in the upper area of the process chamber emp missing value. As a result, there can be no process residues d. H. Reaction gases or their secondary products, accumulate and contribute to particle formation. The flushed areas should Therefore, they are favorably above those to be processed Surface of the substrate, i. H. from these areas the surface of the substrate is visible from. These include also hidden areas, for example chamber wall areas behind the gas dispersion device, so that in principle all  above the substrate surface to be processed Areas that are accessible for flushing. Rinsing the chamber walls in the lower area of the process chamber, d. H. below of the substrate to be processed is also recommended worth, because particles from there also from air turbulence the surface of the substrate can be thrown.

It is also recommended that the chamber walls depend on to be flushed with deposits depending on the degree of contamination. So is with for example in weak or not soiled areas Rinsing is not necessary, but more rinsing should be done take place in areas of higher stress.

In addition to preventing particle formation, the inventor points out CVD reactor according to the invention has another advantage. With CVD Processes are usually several reaction gases as Re Action gas mixture introduced into the process chamber and there burned in an oxidizing atmosphere, for example. In addition to the desired end products, a number can be used of intermediate and by-products that arise if on the chamber walls or on the gas dispersion device can precipitate. This creates chemical unde finished surfaces on which different absorption and desorption processes take place, which lead to process stabilization can lead. Because of the usually strong ver reduced working pressure and the significantly increased free The process instabilities affect the path length of the gas molecules under certain circumstances may also be done directly on the chamber walls on the deposition processes on the substrate.

Such instabilities can be avoided by using the CVD reactor according to the invention, since the formation of chemically undefined surfaces in the process chamber is largely excluded. Therefore, this method leads especially to sensitive CVD reactions, for example in the deposition of metal oxides, to process stabilization, metal oxide layers are used in particular in the manufacture of highly integrated memory modules as a capacitor dielectric with high dielectric constant or with ferroelectric properties. High dielectric materials include barium strontium titanate (BST) and tantalum oxide (Ta ₂ O ₅ ). Ferroelectric metal oxides are, for example, strontium bismuth tantalate (SBT) and lead zirconium titanate (PZT). Also in the production of sup raleitenden oxides such. B. YBa ₂ Cu ₃ O ₇ , the application of the method according to the invention leads to better process results.

Reduced when using the CVD reactor according to the invention the maintenance effort for the CVD reactors, their status time is extended at the same time. As through the conti Thorough rinsing of the chamber walls also difficult to clean accessible areas, may apply en Maintenance work made easier.

Flushing the chamber walls and the is particularly advantageous Gas dispersion device through largely uniform Ver divide the purge gas on the chamber walls or on the gas dispersion device. In this way, for example, Ver swirls avoided.

A little reactive or inert purge gas is preferably used. Such a preferred purge gas is, for example, nitrogen gas (N ₂ ) or argon (Ar). It is also favorable that the purge gas in the form of an essentially laminar flow is passed over the chamber walls or the gas dispersion device. Laminar streams reduce the risk of vortex formation on the one hand, and on the other hand this enables the reaction gases and their secondary products to be effectively removed from the chamber walls or the gas dispersion device. Preferably, the supply of the purge gas should be set so that in the immediate vicinity of the surfaces to be kept there is an excess of purge gases which, due to the constant supply of new purge gas, keeps reaction gases or their secondary products away from these surfaces.

With this CVD reactor, the additional flushing gas nozzles, located in the area or near the chamber walls a purging gas for purging the chamber walls came into the process be initiated. As a result, the chamber walls in particular especially during the actual CVD deposition, d. H. currency After introducing the reaction gases, constantly with clean Purged gas, so that a on the chamber walls concerned Deposition of reaction gases is largely excluded becomes.

The further flushing gas nozzles in the chamber walls are preferred arranged. The direction of radiation from the flushing gas nozzles can be changed approximately inclined vertically or downwards with respect to the chamber walls be aligned. In the simplest case, the chamber walls face a variety of openings through which purge gas occurs. If the openings in the chamber walls are ge down tend to be a downward facing The laminar current is driven, which is particularly effective Keeps reaction gases away from the chamber walls. Moreover can then on the attachment of purge gas nozzles in the lower loading range of the chamber walls can be dispensed with, since the laminar Flushing stream coming from above also the lower chamber wall area che sweeps over.

It is also beneficial to flush the purging gas nozzles evenly Chamber walls or depending on the degree of loading with Pro Arrange zeß remainders. Especially with the arrangement purging gas nozzles depending on the load level the deposition of process gases saves purging gas and effectively avoided.

Another advantageous embodiment of the invention ß CVD reactor is characterized in that the purge gas nozzles in the upper area of the chamber walls, which is above  a sub located in the CVD reactor and to be processed strats extends, are arranged, and the direction of radiation the purge gas nozzles are aligned approximately parallel to the chamber walls is.

It is further preferred to ent the purge gas nozzles in a ring long along the chamber walls. This ring can be for example openings in different directions sen, so that on the one hand the vertical chamber walls with paral be flushed to these aligned rinsing nozzles as well also chamber walls arranged above the ring to the purge gas are accessible.

In the CVD reactor according to the invention, the gas dispersion has device between the gas inlet nozzles to be introduced of the reaction gas are provided, in each case one or more Purge gas nozzles on. The flowing through these purge gas nozzles Purge gas is distributed evenly over the surface of the Gas dispersion device, d. H. essentially about the un tere side of the gas dispersion device, the process opposing substrate and the gas inlet nozzles and prevents the deposition of reaction gases there. This also clogs the gas inlet nozzles prevented.

The flushing gas nozzles preferably enable an approximately uniform one Distribution of the purge gas over the surface of the gas dispersion onseinrichtung. On the one hand, this can be done using suitable nozzles shape, for example by opening conically to the outside nozzles.

A preferred embodiment of the CVD reactor is further hin characterized in that in the edge region of the gas disper Sionseinrichtung a ring is arranged in which a lot Number of purge gas nozzles for introducing a purge gas hen is, the direction of radiation of these purge gas nozzles approximately  runs parallel to the chamber walls of the process chamber or is directed towards the chamber walls.

The ring around the gas dispersion device is provided with a large number of purge gas nozzles, through which the Chamber walls can be blown with a purge gas. The Ring can either be fixed with the gas dispersion device connected or separated from it and separately in the process always be fixed.

In the following, the invention is illustrated by means of an embodiment game explained and shown schematically in figures. It demonstrate:

Fig. 1 is an overview of an exemplary CVD reactor,

FIGS. 2 to 4 different embodiments of Spülgasdüsen in the chamber walls,

Fig. 5 shows a gas dispersion device with integrated purge gas nozzles and

Fig. 6 shows the gas dispersion device with integrated purge gas ring in plan view.

First, the operation of a CVD reactor will be explained using the example of an SBT deposition. For this purpose, reference is made to FIG. 1. The CVD reactor 5 shown there comprises a process chamber 10 , into which a substrate 20 can be introduced via a lock area 15 . The introduced substrate 20 , for example a silicon wafer, lies in the process chamber 10 on a carrier 25 and is sucked onto it, for example by negative pressure. A heater 30 for tempering the carrier 25 and the substrate 20 is located below the carrier 25 . In the present embodiment, an electrical heater 30 with connections 35 is used. A gas dispersion device 40 is arranged opposite the carrier 25 in the upper region of the process chamber 10 . This serves on the one hand for mixing reaction gases with oxidizing gases and on the other hand for evenly distributing the resulting reaction gas mixture within the process chamber 10 and in particular in the vicinity of the substrate 20th

The gas dispersion device 40 has two inlet openings. The so-called precursor gas is supplied to the gas dispersion device 40 through the first inlet opening 45 . During an SBT deposition, the precursor gas contains volatile strontium, bismuth and tantalum complexes, which preferably contain β-diketonates. So that this mixture is gaseous, it must first be evaporated. For this purpose, the complexes which are initially solid are dissolved in a suitable solvent, for example in octane and decane, and are subjected to evaporation in a so-called flash evaporator and mixed with a carrier gas (Ar). The resulting gaseous mixture subsequently arrives at the gas dispersion device 40 . An oxidizing gas of argon and oxygen is added to the mixture in this. Oxygen is required to burn the complexes so that a metal oxide layer can form on the surface 50 of the substrate 20 .

Mixing the gaseous. Complexes with the oxidation gas take place within the gas dispersion device 40 in the area of the mixing zone 55 , which are located on the side of so-called partition plates 60 . Below the mixing zone 55 are the gas inlet nozzles 65 , through which the resulting reaction gas mixture in the process chamber 10 ge reaches.

On the side of the gas dispersion device 40 there is a circumferential ring 70 in the upper region of the process chamber 10 , which ring is provided with a multiplicity of flushing gas nozzles 75 '.

Through this an inert purge gas, for example nitrogen, is introduced into the process chamber 10 , the purge gas nozzles 75 'being oriented such that they blow on the chamber walls 80 of the process chamber 10 . As a result, the onsgas mixture introduced into the process chamber 10 is kept away from the chamber walls 80 so that no process residues can be deposited there. Essentially, the regions 85 of the chamber walls 80 lying above the substrate 20 are supplied with purge gas. These are mainly the areas from which the surface 50 of the substrate 20 can be seen, or which are above the substrate 20 . Since the general gas flow within the process chamber 10 is directed from top to bottom, the blowing on these areas 85 is sufficient to exclude the risk of contamination of the surface 50 of the substrate 20 . In addition to the purge gas introduced via the ring 70 , purge gas is also introduced through openings 90 below the carrier 25 and openings 95 in the area of the lock area 15 .

When an SBT layer is deposited, the substrate 20 must be heated to temperatures between 250 ° C. and 650 ° C. In contrast, the temperature of the chamber walls 80 and the gas dispersion device 40 is at a temperature of approximately 200 ° C. In order to prevent an undefi ned deposition on these relatively cold surfaces, purging gas is continuously blown onto the relevant surfaces during the introduction of the reaction gas mixture. The used process gases and the purging gases falling off the chamber walls are sucked off through suction pipes 100 with a large cross section, which are connected to the latter in the lower region of the process chamber 10 . The flushing gas nozzles 75 'integrated into the gas dispersion device 40 ' are explained in detail in later figures.

In the following, various possibilities of flushing gas nozzles and their arrangement in the chamber walls are explained. In FIG. 2 a section of a chamber wall 80 is shown in the upper portion of a process chamber. The chamber wall 80 is provided with a plurality of Spülgasdüsen 75 ", whose From the beam direction is tet be rich 105 perpendicular to the chamber wall 80. The chamber wall 80 is to enveloped, which is used by a jacket 110 for feeding the purge gas. These are located on the casing 110 suitable piping 115 .

In Fig. 3 80 oriented rinsing gas nozzles are shown obliquely from the chamber wall. Their direction of radiation 105 is directed to un th, so that the purge gas introduced forms a downward laminar gas stream from the beginning. The flushing gas nozzles 75 ″ are preferably arranged in a regular pattern in the chamber wall. This is shown in the chamber wall section shown in FIG. 4.

The arrangement of the flushing gas nozzles 75 in the Gasdispersionsein direction 40 is shown in Fig. 5. In the lower region of the gas dispersion device 40 , the purge gas nozzles 75 are located between the gas inlet nozzles 65 . These are housed in a flat chamber system 120 , which has a lateral inlet opening 125 for supplying the purge gas. The flat chamber system 120 is penetrated by many channels 130 , which create a connection between the interior 135 of the gas dispersion device 40 and the process chamber 10 , but are sealed against the flat chamber system 120 . These channels 130 go in their, the process chamber 10 facing end into the gas inlet nozzles 65 . Between each gas inlet nozzle 65 there is a purge gas nozzle 75 which is formed by a simple opening in the flat chamber system 120 facing the process chamber 10 . The purge gas flowing from the purge gas nozzles 75 is initially distributed relatively uniformly over the surface 140 of the gas dispersion device 40 . In the area of the gas inlet nozzles 65 , it is now flushed away with the reacting gas mixture. This avoids over painting the surface 140 with reaction gases.

The two-dimensional arrangement of the purge gas nozzles and the gas inlet nozzles is shown in FIG. 6. Both types of nozzles are arranged in the same, but staggered pattern. In plan view of the Gasdispersionseinrich device 40 is in its edge region 145 continues to see the gas dispersion device 40 encircling ring 70 with integrated purging gas nozzles 75 '. These serve to blow on the chamber walls and to form a uniform and laminar flow along the chamber walls. If these purging gas nozzles 75 'are sufficiently distributed around the Gasdispersionseinrich device 40 and a uniform purging of the chamber walls is achieved, the purging gas nozzles in the chamber walls can be dispensed with. The edge area 145 extends essentially to the side of the gas dispersion device 40 up to the chamber walls 80 of the process chamber 10 , so that the ring 70 shown in FIG. 1 also lies in the edge area 145 of the gas dispersion device 40 .

LIST OF REFERENCE NUMBERS

5

CVD reactor

10

process chamber

15

lock area

20

substratum

25

carrier

30

heater

35

Heating connections

40

Gas dispersion means

45

first inlet opening

47

second inlet opening

50

Surface of the substrate

55

mixing zone

60

separating plate

65

Gas inlet nozzles

70

ring

75

.

75

'

75

"Purge gas nozzles

80

chamber walls

85

Areas of the chamber walls

90

.

95

openings

100

suction pipes

105

radiation direction

110

coat

115

piping

120

Flat-chamber system

125

inlet port

130

channels

135

inner space

140

Surface of the gas dispersion device

145

Edge area of the gas dispersion device

Claims (3)

1. CVD reactor with a process chamber ( 10 ) the chamber walls ( 80 ), a gas dispersion device ( 40 ) for introducing a reaction gas or a reaction gas mixture into the process chamber ( 10 ) and a carrier ( 25 ) for holding a substrate to be processed ( 20 ), wherein in the region of the chamber walls ( 80 ) a multiplicity of purging gas nozzles ( 75 ) for introducing a purging gas into the process chambers ( 10 ) are arranged, and wherein the purging gas nozzles ( 75 ) are oriented such that at least some areas of the gas dispersion device ( 40 ), which is located above the surface ( 50 ) of the substrate ( 20 ) to be processed, are subject to a supply of purge gas,
wherein the flushing gas nozzles ( 75 ) are arranged in the gas dispersion device ( 40 ) between gas inlet nozzles ( 65 ) for introducing a flushing gas,
wherein the purge gas nozzles ( 75 ) are accommodated in a flat chamber system ( 120 ) which is penetrated by a plurality of channels ( 130 ) which form a connection between an interior ( 135 ) of the gas dispersion device ( 40 ) and the process chamber ( 10 ) and opposite the flat chamber system ( 120 ) are sealed,
the channels ( 130 ) merging into the gas inlet nozzles ( 65 ) in their ends facing the process chamber ( 10 ) and,
wherein between two gas inlet nozzles ( 65 ) there is a flushing gas nozzle ( 75 ) which is formed by an opening in the flat chamber system ( 120 ) facing the process chamber ( 10 ). 2. CVD reactor according to claim 1, characterized in that in the edge region ( 145 ) of the gas dispersion device ( 40 ) a ring ( 70 ) is arranged, in which a plurality of further flushing gas nozzles ( 75 ') is provided for introducing a flushing gas, wherein the radiation direction ( 105 ) of these further flushing gas nozzles ( 75 ') runs approximately parallel to the chamber walls ( 80 ) of the process chamber ( 10 ) or is directed towards the chamber walls ( 80 ). 3. CVD reactor according to claim 1, characterized in that further purge gas nozzles ( 75 ") are arranged in the chamber walls ( 80 ), the radiation direction ( 105 ) of these wide ren purge gas nozzles ( 75 ") inclined approximately vertically or downwards with respect to Chamber walls ( 80 ) is aligned.