DE4142877A1 - CVD assembly - has structured separate delivery of reaction gas and inert gas to zones of wafer substrate on hot table in chamber - Google Patents

Abstract

A semiconductor wafer (1) is placed on a hot table (2) within a CVD reaction chamber (4). Gas blowing units (6a) at a gas head (5) deliver a CVD reactor gas (A) to the central main section of the wafer (1). Separate gas units (6b) delivery simultaneously an inert gas (B) to the edges of the wafer (1). The gas head (5) has a number of gas units (6a,6b), separate from each other. The wafer (1) temp. is held at a given level, and the pressure in the CVD reaction chamber (4) is between 100 Torr and atmospheric pressure. A high quality CVD layer with consistent thickness is deposited on the wafer (1), with reduction in the amt. of reaction gas (A) required and the volume of undesired residual particles. Pref. the two gas units (6a,6b) are on a common plane at a given gap from the wafer (1). The wafer (1) is generally circular, and the first unit (6a) is also circular with a dia. 30-50 mm less than the wafer dia. The second gas unit (6b) is a circular ring round the first gas unit (6a). ADVANTAGE - The system forms a high grade film on the substrate, with consistent thickness and quality, with a reduced consumption of reaction gas.

Description

The present invention relates to a CVD (gas phase) deposition) method and a device for its passage leadership and especially on the training of a thin Layer on a semiconductor wafer suitable improvement of a CVD method and an apparatus for performing this Ver driving.

Fig. 13 is a cross sectional view of a CVD apparatus as described in Japanese Patent Laid-Open No. 2-2 83 696. This CVD apparatus has a heating table for holding a semiconductor wafer 1 on which a CVD layer (not shown) is to be formed, a heater 3 for heating the sample table 2 , a reaction chamber 4 in which the semiconductor wafer 1 is to be processed by means of CVD, a gas head 5 arranged at a distance from the sample holder 2 with a plurality of gas injection openings 6 for supplying reaction gas A, a reaction chamber wall 7 surrounding the chamber 4 , a discharge gas ring 8 , a chamber 9 for discharged gas, a discharge path arranged near the reaction chamber wall 7 10 , a gas discharge opening 11 , a suction flange 12 , a sample table gap 14 to prevent heat dissipation from the sample table 2 as a result of conduction processes and to allow the sample table 2 to rotate, an N ₂ injection opening 15 and an N ₂ injection ring 16 .

A CVD apparatus of the structure described can form a CVD layer on the semiconductor wafer 1 by aligning reaction gas A from the gas injection openings 6 onto the semiconductor wafer 1 previously heated on the heating table 2 . The growth rate of the CVD layer depends on the concentration of the gas supplied from the gas head 5 to the semiconductor wafer 1 . It is therefore necessary to keep the flow of the reaction gas A stable and uniform so that the concentration of the reaction gas A at any point above the semiconductor wafer 1 is stable and uniform in order to obtain a uniform thickness of the CVD layer.

As a result of the CVD reaction, the reaction gas A generates undesired residue particles which adhere to some sections of the inside of the reaction chamber wall. The residue particles D then fall down from the wall of the reaction chamber and adhere to the semiconductor wafer 1 . The residue particles D are therefore the cause of reductions in the yield. If the reaction chamber were cleaned frequently to remove the residue particles D and prevent the yield from decreasing, the productivity would be reduced. It is therefore necessary to reduce the generation of residue particles and to remove the generated particles D together with the discharged gas C from the reaction chamber.

The main part of a conventional CVD apparatus is shown in Fig. 14. An enlarged cross-sectional view of the gas head part of the CVD apparatus according to FIG. 14 is shown in FIG. 15. This continuously operating CVD apparatus has a sample table 2 for transporting a plurality of semiconductor wafers 1 , on which a (not shown) CVD film is to be formed, a heater 3 for heating the sample table 2 and the semiconductor wafer 1 fastened thereon to a predetermined temperature , a plurality of gas heads 5 having a plurality of slits all around which face the semiconductor wafer 1 for supplying reaction gas A to the semiconductor wafer 1 in a uniform manner, and a hood 20 which is arranged to cover the plurality of gas heads 5 and which Exhaust gases C collected on.

In the conventional CVD apparatus for continuous operation with the structure described above, reaction gas A supplied from the end of the gas head 5 spreads horizontally and flows out as exhaust gas C without reaching the semiconductor wafer 1 . Reaction gas A, which does not reach the wafer 1 , generates unwanted residue particles D by a CVD reaction, which adhere to the outer wall of the gas head 5 , the inner wall of the hood 20 or the like. These residue particles D fall down and adhere to the semiconductor wafer 1 , which leads to a decrease in the yield. It is necessary to shut down the equipment periodically in order to remove the undesired particles D. This leads to a reduction in the operating efficiency of the apparatus.

It is an object of the present invention to provide a CVD method efficient formation of a CVD film of uniform thickness and good Quality and an apparatus for performing this method specify, in particular the amount of reaction used gases should be reduced.

A CVD method according to one aspect of the invention has the fol steps: placing a semiconductor wafer on a Heating table within a CVD reaction chamber, simultaneous Injection of CVD reaction gas from a first injection area a gas head, which is arranged opposite the wafer and a Has a plurality of separate gas injection areas, towards at least the central main area of the wafer, and Injection of an inert gas from a second gas injection area of the  Gas head towards an area of the peripheral part of the wafer, the Temperature of the wafer at a predetermined value and the pressure the CVD reaction chamber within a range of 100 Torr to Atmospheric pressure is maintained to form a high CVD film Quality and uniform thickness on the wafer as well as Reduction of the amount of reaction gas consumed and the amount undesirable residue particles D.

A CVD apparatus according to a further aspect of the invention has open: a CVD reaction chamber in which the pressure within a Range of 100 torr to atmospheric pressure is maintained Heating table for holding the semiconductor wafer placed on it the reaction chamber at a predetermined temperature, one gas head arranged opposite the wafer for emitting gas in Direction of the wafer, the gas head being a first gas injection area for supplying CVD reaction gas at least to the central main area of the wafer and a second gas injection area for feeding of inert gas to the edge region of the wafer, the first and second gas injection area in a common one to the wafer are arranged at a predetermined distance, whereby a high quality CVD film of uniform thickness on the wafer formed and the amount of reaction gas consumed and the amount unwanted residue particles can be reduced.

Further features and advantages of the invention result from the explanation of exemplary embodiments with reference to the figures.

From the figures show:

Fig. 1 is a cross sectional view of a CVD apparatus according to a first embodiment;

Fig. 2 is an enlarged partial cross-sectional view of the CVD apparatus shown in FIG. 1 for clarity of the gas flow within the reaction chamber,

Fig. 3A is a sectional view showing an example of a use in a first embodiment gas head,

Fig. 3B is a graph showing the relationship between the TEOS concentration and the diameter D denotes the first Gaseinblasgebietes,

FIG. 4 shows a perspective illustration of a CVD film which was formed using the gas head according to FIG. 3 to illustrate an example of the layer thickness distribution, FIG.

Fig. 5 is a cross sectional view of another example of a gas head used in the first embodiment,

Fig. 6 a, dividing a perspective view of the CVD film which has been formed using the gas head of Fig. 5 showing its layer thickness-,

Fig. 7 is a perspective view of a CVD film was formed using the gas head of Fig. 3, showing a further example of its layer thickness distribution,

Fig. 8 is a perspective view of a CVD film was formed using the gas head of Fig. 3, showing a further example of its layer thickness distribution,

Fig. 9 is a cross sectional view of a CVD apparatus according to a second embodiment;

Fig. 10 is a diagram schematically showing a CVD apparatus according to a third embodiment;

Fig. 11 is a diagram schematically showing a CVD apparatus according to a fourth embodiment,

FIG. 12A is a cross sectional view schematically showing the gas head in a CVD apparatus in a fifth embodiment,

FIG. 12B is a bottom view schematically showing the gas cap of FIG. 12A,

Fig. 13 is a cross sectional view of a conventional CVD apparatus,

Fig. 14 is a side view of the main parts of a conventional CVD apparatus for continuous operation (with some parts have been removed),

Fig. 15 is an enlarged cross-sectional view of the gas head portion of the CVD apparatus mission is to continuously current operating according to Fig. 14.

In the figures, the same reference symbols denote equivalent or corresponding parts.

Fig. 1 shows a CVD apparatus according to a first embodiment, and the manner of gas flow in the vicinity of the gas head of the CVD apparatus according to Fig. 1 is shown in Fig. 2. The CVD apparatus according to the first embodiment is similar to that of FIG. 13, except that the gas head 5 is divided into a plurality of gas injection areas by a partition 10 . The central first gas injection area has a plurality of gas discharge openings 6 a for reaction gas A such as. B. TEOS, O ₃ and N ₂ . The second gas injection region surrounding the central first gas injection region has a plurality of outlet openings 6 b for inert gas B, such as N ₂ . The reaction gas A and inert gas B blown into the reaction chamber at the same speed form a speed boundary layer of uniform thickness and a temperature boundary layer within the gas flow, as in the CVD apparatus according to FIG. 13 with a single gas injection region. In Fig. 2, the dashed line E denotes the boundary line of the reaction gas concentration, and the dashed line F denotes the boundary line of the temperature distribution. The temperature limit line F, which indicates the limit of the temperature required for activation for TEOS and 03, is essentially parallel above the surface of the heating table 2 .

The diameter of the first central gas injection area is set within an area in which near the surface of the wafer 1 a similar concentration distribution of the reaction gas A as in the prior art can be obtained without being influenced by the inert gas in the peripheral area. In the section above the surface of the edge part of the wafer 1 , the reaction gas A is diluted with inert gas B and thus has a lower concentration.

Especially in the hatched area A between the reaction gas concentration limit line E and the temperature limit line F in FIG. 2, the generation of undesirable residue particles D is reduced due to the low concentration of the reaction gas, although the temperature of the reaction gas is high enough for a reaction.

Fig. 3 shows an example of a gas head 5. The gas head 5 has an outer diameter of 150 mm, which is the same as that of the wafer 1 , and the central first gas injection region has a diameter of 110 mm. The gas head 5 is arranged at a distance of 7 mm from the wafer 1 . The reaction gas, which is mixed from N ₂ , TEOS and O ₃ , and the inert gas, which is N ₂ , are injected at an identical flow rate from the central first gas injection region or the second gas injection region surrounding it. The outer diameter of the first reaction gas injection area is determined by a numerical simulation that takes into account the diffusion of the TEOS within the gas chamber 4 .

Fig. 3B is a graph showing the change in TEOS concentration Y _T on the outer surface of a 6-inch (15 cm) wafer depending on the change in diameter D of the first reaction gas blowing area. It can be derived from FIG. 3 that Y _{T is} constant if D is sufficiently larger than the wafer diameter. However, Y _D suddenly drops as D becomes smaller due to the dilution by N ₂ . It should be noted that the drop in Y _T does not begin immediately when the diameter D becomes smaller than the wafer diameter, and that the value remains approximately constant up to a diameter D of approximately 110 mm. It is understood from this that the diameter can be reduced down to D = 110 mm for a wafer with a diameter of 150 mm in order to supply the reaction gas uniformly to the surface of the wafer.

Fig. 4 shows the thickness distribution of a CVD (SiO ₂ ) layer, which by emission of reaction gas A (a mixed gas of N ₂ , TEOS and O ₃ ) and inert gas B (N ₂ ) with an average flow rate of about 26 mm / s using the gas head it was formed according to Fig. 3. The vertical axis in FIG. 4 denotes the thickness of the SiO ₂ layer. It can be seen from FIG. 4 that the thickness of the CVD (SiO ₂ ) layer over the central and the peripheral region of the wafer 1 is approximately the same. The reaction gas A supplied from the central region of the gas head according to FIG. 3 apparently reaches the entire surface of the wafer 1 . Another example of a gas head is shown in FIG. 5. The gas cap of FIG. 5 is similar to that of Fig. 3, except that the diameter of the first Gaseinblasgebietes is 90 mm reduced. Fig. 6 shows the thickness distribution of a CVD (SiO ₂ ) layer, which by emission of reaction gas A (a mixed gas of an N ₂ , TEOS and O ₃ ) and inert gas B (N ₂ ) with an average flow rate of about 26 mm / s was formed using the gas head according to FIG. 5. It can be seen from FIG. 6 that the thickness of the CVD (SiO ₂ ) layer in the edge part has decreased more than in the central part of the wafer 1 . This means that from the central region of the gas head according to FIG. 5, the reaction gas A fed in the edge region above the wafer 1 is diluted with inert gas B, so that its concentration has dropped.

From the results shown above, it can be seen that the diameter of the central first Gaseinblasgebietes in the case that the outer diameter of the wafer 1 150 mm and the distance between the gas head 5 and the wafer 1 7 mm, can be reduced mm to about 110th Since the supply amount of reaction gas A is proportional to the square of the diameter of the first injection region, both the amount of reaction gas A consumed and the amount of undesired residue particles D can be reduced compared to the usual amounts.

The minimum diameter of the reaction gas injection area depends on the size of the wafer facing it, the pressure in the reaction chamber 4 , the gas flow rate, the type of gas and the distance between the wafer and the gas head.

By simulation of the diffusion process, it was determined that the limit for the diameter D is about 40 mm below the wafer diameter for different wafer diameters under identical conditions as those in FIG. 3B, as shown in Table 1 below:

Table 1

The minimum diameter depends on the pressure in the reaction chamber 4 , the gas flow rate, the type of gas and the distance between the wafer and the gas head. The diameter increases in proportion to the pressure drop, falls in proportion to the increase in flow velocity, falls in proportion to the reduction in the gas diffusion coefficient, and increases in proportion to the increase in the distance between the wafer and the gas head.

Fig. 7 shows the thickness distribution of a CVD layer, which by a reaction gas A (a mixed gas of N ₂ , TEOS and O ₃ ), which was introduced from the first gas injection region, and an inert gas B (N ₂ ), which from the second Gas injection area was supplied, whereby an average speed ratio of 1: 0.77 was maintained and the gas head was used according to FIG. 6, was formed. It can be seen from FIG. 7 that the edge part of the CVD layer is thinner than the central part. It can be assumed that this is caused by the lowering of the concentration of the reaction gas A with a slight pressure against the wafer 1 by the inert gas B in the vicinity of the edge part of the wafer 1 , since the flow rate of the inert gas B, which comes from the edge part of the Gas head 5 is introduced, is lower than that of the reaction gas A, which is introduced from the central region. Fig. 8 shows the thickness distribution of a CVD (SiO ₂ ) layer which is supplied by an inert gas B (N ₂ ) supplied by a reaction gas A (mixed gas composed of N ₂₁ TEOS and O ₃ ) from the first gas injection region and an inert gas supplied by the second gas injection region average speed ratio of 1: 1.19 was formed using the gas head of FIG. 3. The thickness of the CVD layer is increased in the edge area compared to the central area of the wafer 1 . It can be assumed that this is due to the increase in the concentration of the reaction gas A which is pressed against the wafer 1 by the inert gas B, since the flow rate of the inert gas B supplied from the edge part of the gas head 5 is greater than that of the reaction gas supplied from the central section A is caused.

From FIGS. 7 and 8 is to be understood that the layer thickness distribution of the formed on a wafer 1 CVD layer by changing the average flow velocity of the of the second Einblasgebiet, that is, the periphery of the gas head 5 a supplied inert gas B in relation to the middle Flußgeschwin The reaction gas A supplied from the first gas injection region, that is to say the central section of the gas head 5 , can be controlled. Thus, if the layer thickness of the CVD layer formed on the wafer 1 is for some reason not radially uniform, by changing the layer thickness, the thickness distribution of the CVD layer for eliminating non-uniformities can be made uniform in that the flow rate of the inert gas B , which is supplied from the second gas injection area in the edge region of the gas head 5 , is changed.

Fig. 9 shows a CVD device according to a second embodiment of the invention. The CVD apparatus of FIG. 9 is similar to FIG. 1 except that the gas head 5 is modified. The gas head 5 according to FIG. 9 has, in addition to the central first gas injection region with injection openings 6 a for reaction gas A and the second gas injection region with injection openings 6 b 1 for inert gas B, which surrounds the first gas injection region, a third gas injection region with injection surrounding the second gas injection region openings 6 b 2 for inert gas B. The first, second and third gas injection area are separated from each other by two partitions 17 a and 17 b.

If the first gas injection area has a diameter of 90 mm, the second gas injection area has an outer diameter of 120 mm and the third gas injection area has an outer diameter of 150 mm and the average gas flow rate from the injection openings 6 a, 6 b 1 and 6 b 2 is the same and approximately Is 26 mm / s, the thickness of the CVD layer in the edge part of the wafer 1 drops, as shown in FIG. 6. If the flow rate of the gases supplied from the injection openings 6 a, 6 b 1 and 6 b 2 is selected in accordance with a speed ratio of 1: 1: 1.2, a CVD layer of relatively uniform thickness is obtained. This is because the inert gas B supplied from the injection openings 6 b 2 accelerates the reaction gas A in the edge region of the wafer 1 towards the wafer 1 , whereby the concentration of the reaction gas A is increased in the vicinity of the edge region of the wafer 1 .

In the second embodiment, it is possible to change the diameter of the first gas injection area for reaction gas A compared to the further reduce the first embodiment. This means that the amount of reaction gas supplied and the amount of undesirable Residue particle D is further reduced.

Fig. 10 shows schematically a third embodiment of the inven tion. In the device according to the third embodiment, a first and a second gas injection area 6 a 1 and 6 a 2 are separated by a first partition 17 a, and the second and a third gas injection area 6 a 2 and 6 b are separated by a second partition 17 b . O ₃ , TEOS and N ₂ are supplied to the first gas injection region 6 a 1 via flow controllers 19 a, 19 b and 19 c and a valve 18 a. Similarly O _3, TEOS, and N ₂ are flow controllers 19 a, 19 b and 19 c and a valve 18 b to the second Gaseinblasgebiet 6 a 2 supplied. The inert gas N ₂ is fed to the third gas injection region 6 b via a flow controller 19 d. The third embodiment allows more precise control of the concentration of the reaction gas and the relative flow rate of the reaction gas and the inert gas compared to the first and second embodiments, whereby a CVD layer with further improved uniformity of thickness can be obtained.

Fig. 11 shows schematically a fourth embodiment of the invention. The fourth embodiment is a modification of the first embodiment, O ₃ , TEOS and N _{2 being} fed to the first gas injection region 6 a via flow controllers 19 a, 19 b and 19 c and N ₂ , C ₄ H ₈ (isobutene) being the second gas injection region 6 b are supplied via flow controllers 19 d and 19 e. Since C ₄ H _{8 is} highly reactive with the oxygen atoms released by thermal decomposition of O ₃ , the reaction of the oxygen atoms with TEOS can be effectively suppressed, whereby the amount of undesirable residue particles D is reduced.

Although C ₄ H _{8 has been mentioned} as a suitable gas for reducing the amount of undesirable residue particles D, other gases which effectively trap oxygen atoms can also be used. For example, hydrocarbon gases such as C ₂ H ₄ , C ₃ H ₆ and gaseous alcohols such as methanol and ethanol can be used.

The gas head of a fifth embodiment of the invention has the cross-sectional view shown schematically in FIG. 12A and the bottom view shown schematically in FIG. 12B. This gas head is used in a CVD apparatus for continuous operation similar to that shown in FIG. 14 and has a first central injection area 6 a for reaction gas A and a second gas injection area 6 b, which is arranged on both sides of the first injection area 6 a, for inert gas B. In this case, from the central portion 6a of the gas supplied to the reaction gas head A reaches the wafer 1, forming a CVD film. Inert gas B is blown out of both lateral areas 6 b of the gas head 5 with a Flußge speed equal to that of the reaction gas A. Accordingly, the inert gas B spreads horizontally without disturbing the flow of the reaction gas A and is discharged without reaching the wafer 1 .

Since the part of the reaction gas A which is supplied from the gas head 5 and then discharged without having reached the semiconductor wafer 1 is replaced by inert gas B in the fifth embodiment, the undesirable effect that residue particles D are caused by the wafer occurs 1 not reaching reaction gas A are formed and adhere to the outer wall of the gas head 5 and the inner wall of the hood 20 , not on. The product yield and operating efficiency of the device can thus be improved. The amount of the reaction gas A used can be reduced because the required amount of the reaction gas A supplied is reduced in proportion to the reduction in the area of the first gas injection region.

Although TEOS-O _{3 was selected} as an example of a reaction gas in the above-described embodiments, the invention can also be carried out using other reaction gases. Not only N ₂₁ can be used as the inert gas, but He, Ar or the like can also be used.

Claims (17)

1. CVD method with the steps:
Moving a semiconductor wafer ( 1 ) onto a heating table ( 2 ) within a CVD reaction chamber ( 4 ) and
Introducing CVD reaction gas (A) onto at least the central main section of the wafer ( 1 ) from a first gas injection region ( 6 a) of a gas head ( 5 ) which is arranged opposite the wafer ( 1 ) and a plurality of gas injection regions ( 6 a, 6 b), which are separated from one another, and simultaneous supply of inert gas (B) to the region of the edge section of the wafer ( 1 ) from a second gas injection region ( 6 b) of the gas head ( 5 ) while maintaining the temperature of the wafer ( 1 ) at a predetermined temperature and the pressure in the CVD reaction chamber ( 4 ) within a range from 100 Torr to atmospheric pressure,
whereby a high quality CVD layer of uniform thickness is formed on the wafer ( 1 ) while reducing the required amount of reaction gas (A) and the amount of undesirable residue particles (D). 2. CVD method according to claim 1, characterized in that the first and second gas injection region ( 6 a, 6 b) lie in a common plane from the wafer ( 1 ) having a predetermined distance. 3. CVD method according to claim 1 or 2, characterized in that
the wafer ( 1 ) is essentially circular, the first gas injection region ( 6 a) is essentially circular and has a diameter 30-50 mm smaller than the wafer ( 1 ), and
the second gas injection area ( 6 b) annularly surrounds the first gas injection area ( 6 a). 4. CVD method according to any one of claims 1-3, characterized in that the reaction gas (A) and the inert gas (B) from the first or second gas injection region ( 6 a, 6 b) are introduced at the same speed. 5. CVD method according to one of claims 1-3, characterized in that the second gas injection area is divided into a first and a concentric to this second sub-area ( 6 b 1 , 6 b 2 ) and the speed of the inert gas (B) ß which is supplied from the outer second sub-region ( 6 b 2 ) is larger than that of the inert gas (B) supplied from the interior of the first sub-region ( 6 b 1 ). 6. CVD method according to any one of claims 1-3, characterized in that the first gas injection area is divided into a first and in a concentric to this second sub-area ( 6 a 1 , 6 a 2 ) and the reaction gas (A) from the first or second sub-area ( 6 a 1 , 6 a 2 ) is supplied at different speeds. 7. CVD method according to any one of claims 1-6, characterized in that the heating table ( 2 ) is movable and a plurality of wafers can be attached to it. 8. CVD method according to claim 7, characterized in that the first gas injection area ( 6 a) rectangular and the second gas injection area ( 6 b) rectangular and the second gas injection area ( 6 b) quite angular and longitudinally outside of the two sides, where one Direction of movement of the wafer ( 1 ) intersects the rectangle, is arranged. 9. CVD method according to any one of claims 1-8, characterized characterized in that the inert gas (B) is a gas from the stick group consisting of substance, helium and argon. 10. CVD device with:
a CVD reaction chamber ( 4 ) in which the pressure is kept in a range from 100 torr to atmospheric pressure,
a heating table ( 2 ) for receiving a semiconductor wafer ( 1 ) and holding it at a predetermined temperature in the reaction chamber ( 4 ),
a gas head ( 5 ) arranged opposite the wafer ( 1 ) for supplying gas to the wafer, the gas head ( 5 ) having a first gas injection region ( 6 a) for supplying CVD reaction gas (A) at least to the central main region of the wafer ( 1 ) and a second gas injection region ( 6 b) for supplying inert gas (B) to the edge region of the wafer ( 1 ) and the first and second gas injection regions ( 6 a, 6 b) lie in a common plane at a predetermined distance from the wafer ( 1 ) whereby a high quality CVD layer of uniform thickness can be formed on the wafer ( 1 ) while reducing the amount of reaction gas (A) and the amount of undesirable residue particles (D). 11. CVD apparatus according to claim 10, characterized in that the wafer ( 1 ) is substantially circular, the first gas injection region ( 6 a) is substantially circular and has a smaller diameter than the wafer ( 1 ) and the second gas injection region ( 6 b) surrounds the edge of the first gas injection region ( 6 a) in a ring shape. 12. CVD device according to claim 10 or 11, characterized in that the reaction gas (A) and the inert gas (B) from the first or second gas injection region ( 6 a, 6 b) are fed at the same speed. 13. CVD device according to claim 10 or 11, characterized in that the second gas injection area ( 6 h) is divided into a first and a concentric with this second sub-area ( 6 b 1 , 6 b 2 ), the speed of the outer second sub-area ( 6 h 2 ) supplied inert gas (B) is greater than that of the inner first sub-area ( 6 b 1 ) supplied inert gas (B). 14. The apparatus according to claim 10 or 11, characterized in that the first gas injection region ( 6 a) is divided into a first and with this concentric second sub-region ( 6 a 1 , 6 a 2 ), the reaction gas (A) from the first or second sub-area ( 6 a 1 , 6 a 2 ) is supplied at different speeds. 15. CVD device according to one of claims 10-14, characterized in that the heating table ( 2 ) is movable and can accommodate a plurality of wafers. 16. CVD apparatus according to claim 15, characterized in that the first injection region ( 6 a) is rectangular and the second gas injection region ( 6 b) arranged rectangularly outside of the two sides, where a direction of movement of the wafer ( 1 ) intersects the rectangle is. 17. CVD apparatus according to any one of claims 10-16, characterized characterized in that the inert gas (B) from the nitrogen, Helium and argon existing group is selected.