Abstract:
A reactor and method for performing chemical vapor deposition are disclosed. A chemical vapor deposition reactor can have a cylindrical chamber that comprises a cylindrical lid support and an annular gas distribution plate. Said chamber can be configured to have a horizontal laminar flow of at least one gas stream in the radial direction and a vertical downward flow of another gas stream over wafers. A large capacity of a CVD reactor with simple structures, easy maintenance and low consumption of reactants can be achieved. High uniformity, repeatability, reproducibility and consistency of depositing layers on wafers can be obtained.

Description:
TECHNICAL FIELD OF INVENTION 
       [0001]    The present invention relates generally to a reactor and method for performing chemical vapor deposition (CVD). The present invention relates more particularly to a CVD reactor having a cylindrical chamber for deposition of in particular crystalline layers on one or more in particular likewise crystalline substrates. Said chamber comprises a cylindrical lid support and an annular gas distribution plate, which mitigates complexities and costs of building a large size chamber, and said chamber can be configured to have a horizontal laminar flow of at least one stream in the radial direction and a vertical downward flow of another gas stream over wafers to provide repeatability, reproducibility and consistency of chemical vapor deposition processes and to achieve uniformity of deposited layers at reduced consumption of reactants. 
       BACKGROUND 
       [0002]    In general, the gas flow dynamics for high quality layers deposited by CVD favors laminar flow. Laminar flow, as oppose to convective flow, is required to achieve high efficiency of CVD processes and high uniformity of deposited layers. 
         [0003]    Referring now to  FIG. 1 , one type of contemporary reactor is commonly referred to as planetary reactor. The reactor comprises a cylindrical chamber  122  within which chemical vapor deposition is performed, a quartz plate  104  attached to a lid  101  with a gas cooled spacer  120 , a centric gas inlet nozzle  107 , a rotating susceptor  106  holding a plurality of rotating satellites  127 , a heat assembly  126  underneath the susceptor  106 , and a gas collect ring  103  surrounding the periphery of the susceptor  106 . 
         [0004]    Gases enter the cylindrical chamber  122  via the centric inlet nozzle  107  that separates one mixture of gases, such as Group III reactants, from the other, i.e. Group V reactants, prior to their introduction into the cylindrical chamber  122 . The centric inlet nozzle  107  and the exhaust  103  are above the susceptor  106 . The reactant gases flow in the outwardly radial direction from the centric inlet nozzle  107  to the gas collect ring  103 . 
         [0005]    As the reactants in carrier gases proceed from the center toward the periphery, a substantial amount of the reactants is consumed along the way due to parasitic reactions forming particles and/or adducts in the gas phase, so as to be called as the depletion effect. As a result, the depositing rate falls along the flow direction. For an outwardly radial flow of reactant gases, the mass density of reactants in the gas phase decreases due to gradually increased cross-section, which forms another inherent source of non-uniform deposition in such a cylindrical chamber. 
         [0006]    One contemporary approach to mitigate the depletion effect is to use a high gas flow rate to reduce the concentration gradient along the flow direction, but the drawback of this approach is an inherent decrease in efficiency of CVD processes and an increased consumption of reactant gases. Another contemporary approach to mitigate the depletion effect caused non-uniformity is rotating wafers and/or satellites. Referring to  FIG. 1 , the susceptor  106  rotates at approximately 10 rpm and the satellites  127  rotate at approximately 50 rpm. Making such kinds of the susceptor capable of rotating multiple wafers and/or satellites in a sealed chamber under very dynamic CVD conditions is inherently expensive and complicated, which has impeded a further increase of the wafer capacity of the planetary reactor. 
         [0007]    Furthermore, referring to  FIG. 1 , due to lack of active gases flowing through, heavy deposits are inherently accumulated on the down surface of the quartz plate  104 , which not only depletes the reactants but also deteriorates CVD processing. In order to precisely assembly the components, such as the nozzle  107  and the quartz plate  104  together to the lid  101 , the structure of the lid  101  is inherently complex. It is inherently difficult to maintain or clean the lid  101  in routine operation. As a result, repeatability, reproducibility and consistency of the CVD processes can not be ensured. Deformation of the lid  101  under low pressures also influences CVD processing and further impedes the scale up of the cylindrical chamber size in diameter. 
         [0008]    Referring to  FIG. 2 , another type of contemporary reactor is commonly referred to as turbo-disc reactor. The reactor comprises a cylindrical chamber  222 , a flow flange  204  where all the reactant gases are distributed and delivered vertically into the cylindrical chamber  222 , a wafer carrier  206  spinning at speeds between 500 and 1500 rpm, a heater assembly  226  underneath the wafer carrier  206  configured to heat wafers  200  to desired process temperatures, and an exhaust  203  at the bottom side of the cylindrical chamber  222 . The wafer carrier  206  comprises a plurality of pockets, each of which is configured to contain a wafer  200 . 
         [0009]    In such a reactor, the longitudinal depletion effect of reactants in the flow direction and the effect of lid deposition on CVD processes are substantially mitigated. A few inlets respectively for introduction of reactants require a minimum chamber height for a uniform mixture of reactants above the surface of the wafer carrier  206 . An enlarged diameter of a chamber needs an increased height of the cylindrical chamber. Particularly at high pressures and temperatures, thermal convection occurs severely in a large volume of chamber. The gas flow tends to be undesirably turbulent. In order to suppress thermal convection, a high gas flow may be applied and the wafer carrier  206  may spin at very high speeds. One of the drawbacks is an increased consumption of reactants, and the other is that to spin a large wafer carrier at a very high speed substantially without wobbling is inherently extremely difficult. Deformation of the lid  201  under low pressures may influence CVD processing and further impedes the scale up of the cylindrical chamber size in diameter. 
         [0010]    Referring to  FIG. 3 , another type of contemporary reactor is commonly referred to as close coupled showerhead reactor. The reactor comprises a cylindrical chamber  322 , a showerhead  304  through where all the reactant gases are distributed and delivered into chamber  322 , a wafer carrier  306  rotating at speeds between 5 and 100 rpm, a heater assembly  326  underneath the rotating wafer carrier  306  configured to heat wafers  300  to desired process temperatures, and an exhaust  303  at the bottom side of the cylindrical chamber  322 . The wafer carrier  306  comprises a plurality of pockets, each of which is configured to contain a wafer  300 . 
         [0011]    In such a reactor, thousands of separate fine orifices with complex water passages formed in the showerhead  304  can deliver and distribute gases uniformly over entire wafer carrier  306 . The cylindrical chamber height can be substantially reduced to suppress buoyancy as well as parasitic reactions. However, the showerhead  304  is inherently complicated and expensive. Complex water passages around fine orifices face a great risk of leaks. Furthermore, a short distance from the showerhead  304  to the wafer carrier  306  inherently causes heavy deposits on the surface of the showerhead  304 . The presence of thousands of separate fine orifices prevents easy and reproducible cleaning after CVD processing. As a result, repeatability, reproducibility and consistency of the CVD processes can not be ensured. Deformation of the lid  301  under low pressures also influences CVD processing and further impedes the scale up of the cylindrical chamber size in diameter. 
         [0012]    Referring to  FIG. 4 , another type of reactor is commonly referred to as rectangular reactor. The reactor may comprise a rectangular chamber  422 , the first gas inlet  407  disposed at one side of the cylindrical chamber  422  for a horizontal flow of gases, the second gas inlet  404  located at the top of the cylindrical chamber  422  for a vertical flow of gases, a susceptor  406 , a heater  426  beneath the susceptor  406 , and an exhaust  403  disposed at the other side of the cylindrical chamber  422 . 
         [0013]    A horizontal gas stream flows from the first gas inlet  407  to the exhaust  403  parallel to the surface of the susceptor  406 . A vertical gas stream flows downwardly to suppress thermal convection for a laminar flow of the horizontal gas stream. Two gas streams mix in the vicinity of the wafers  400 , which reduces parasitic reactions in the gas phase. However, the horizontal gas stream still suffers undesired longitudinal depletion effect. The rotation of wafers  400  may be used to compensate the depletion effect. For this type of a non-cylindrical chamber, the side-wall effect on flowing pattern perpendicular to the horizontal gas flow direction can deteriorate uniformity of depositing layers and reduce efficiency of CVD processes, which inherently prevents to build up a large size chamber. 
         [0014]    Moreover, throughput requirements from production reactors have become important. The contemporary approach to increase throughput is typically to build larger chambers. Referring to the aforementioned reactors, the top plates of cylindrical chambers are not supported in the center and the gases are introduced through gas inlet devices disposed in the top plate. The thermal and mechanical stress may consequently tend to break top plates prematurely at great costs. So, the aforementioned reactors suffer from inherent deficiencies that tend to detract from their overall utility and desirability. 
         [0015]    This invention has an object to provide a CVD reactor which eliminates the disadvantages of the abovementioned conventional chemical vapor deposition reactors. 
         [0016]    It is another object of the invention to provide a CVD reactor which can easily and economically be scaled up so as to increase throughput and reduce the costs of ownership. 
         [0017]    It is another yet object of the invention to provide a CVD reactor which deposit layers on substrates with good repeatability, reproducibility, controllability and uniformity. 
         [0018]    It is another yet object of the invention to provide a CVD reactor which is not substantially susceptible to undesirable depletion effect in the gas flow direction, undesirable thermal convection and undesirable parasitic reactions in the gas phase, so as to provide improved uniformity and enhanced efficiency of CVD processes. 
       BRIEF SUMMARY OF THE INVENTION 
       [0019]    According to one embodiment, a CVD reactor generally comprises a cylindrical chamber which further comprises a cylindrical lid support concentrically disposed in the center of a cylindrical chamber. The cylindrical lid support can have an upper ridge whereon the central portion of a lid can rest. Deformation of the lid centrally supported by the cylindrical lid support can be substantially prevented under low pressures, which inherently mitigates complexities and costs of construction. 
         [0020]    According to another embodiment, a CVD reactor generally comprises a cylindrical chamber which can be configured to have a horizontally disposed annular gas distribution plate. The annular gas distribution plate bends a horizontal gas flow to a vertical gas flow downwardly to the surface of an annular wafer carrier, which not only mitigates complexities and costs of construction but also provides a vertical gas flow which can suppress thermal convection above heated wafers to reduce parasitic reactions in the gas phase and to maintain another horizontally injected gas flow in parallel or obliquely to the annular wafer carrier in contact with the surface of the annular wafer carrier. Moreover, an active vertical gas flow can effectively prevent deposits of reactants on the down surface of the annular gas distribution plate. 
         [0021]    According to another yet embodiment, a CVD reactor generally comprises a cylindrical chamber which can be further configured for an inwardly radial flow of gases above the surface of an annular wafer carrier. When gases passage horizontally into and out of the cylindrical chamber at the periphery and the center, the reactant gases still suffer the depletion effect. On the other hand, the gas flow velocity increases due to radially converging geometry and the mass density of reactants increases due to concomitant converging reactant gases. The increased gas velocity can reduce the boundary layer thickness, which consequently increases the mass transport of reactants from the gas phase to the surface of a wafer. Therefore, the radially converging gas flow can inherently compensate the depletion effect to provide uniform deposition, which substantially mitigates complexities and costs of construction particularly related to wafer carriers and/or susceptor. 
         [0022]    Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. This invention will be more fully understood in conjunction with the following detailed description taken together with the following drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  is a side view of a contemporary planetary chemical vapor deposition (CVD) reactor chamber; 
           [0024]      FIG. 2  is a side view of a contemporary turbo-disc CVD reactor chamber; 
           [0025]      FIG. 3  is a side view of a contemporary close coupled showerhead CVD reactor chamber; 
           [0026]      FIG. 4  is a side view of a rectangular CVD reactor chamber; 
           [0027]      FIG. 5  is a side view of a CVD reactor chamber, wherein a gas inlet ring  507  horizontally disposed in the periphery of chamber  522 ; 
           [0028]      FIG. 6  is a side view of a CVD reactor chamber, wherein a gas inlet ring  607  horizontally disposed in the periphery of chamber  622  and a gas injection plate  604  at the top of chamber  622 ; 
           [0029]      FIG. 7  is a side view of a CVD reactor chamber, wherein a gas inlet ring  707  horizontally disposed in cylindrical lid support  702  and a gas injection plate  704  at the top of chamber  722 ; 
           [0030]      FIG. 8  is a side view of a CVD reactor chamber, wherein a gas injection plate  804  at the top of chamber  822 ; 
           [0031]      FIG. 9  is a side view of a CVD reactor chamber, wherein a gas inlet ring  907  horizontally disposed in the periphery of chamber  922  and a gas distribution plate  904  horizontally disposed in chamber  922 . 
           [0032]      FIG. 10  is a side view of a CVD reactor chamber, wherein a gas inlet ring  1007  horizontally disposed in cylindrical lid support  1002  and a gas distribution plate  1004  horizontally disposed in chamber  1022 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0033]    The invention and its various embodiments can now be better understood by turning to the following detailed description of the preferred embodiments which are presented as illustrated examples of the invention defined in the claims. It is expressly understood that the invention as defined by the claims may be broader than the illustrated embodiments described below. 
         [0034]    Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the invention. Therefore, it must be understood that the illustrated embodiment has been set forth only for the purposes of example and that it should not be taken as limiting the invention as defined by the following claims. 
         [0035]    According to one embodiment, as shown in  FIG. 5 , a CVD reactor can have a generally cylindrical chamber  522 . A generally cylindrical chamber  522  comprises a generally circular top plate, so as to be the lid  501 , a cylindrical lid support  502 , an annular wafer carrier  506 , support tubes  540   a  and  540   b , a gas inlet ring  507 , an annular gas discharge passage  503   b , a heat assembly  526 , and an exhaust port  509 . 
         [0036]    The cylindrical lid support  502  is preferred to be concentrically disposed in the center of a bottom plate  513  and provides an upper ridge whereon the central portion of the lid of the chamber  522  rests. 
         [0037]    The annular wafer carrier  506  is preferred to be horizontally disposed on the support tubes  540   a  and  540   b . The annular wafer carrier  506  comprises a plurality of pockets, each of which is configured to contain a wafer  500 . 
         [0038]    The gas inlet ring  507  is preferred to be horizontally disposed in the periphery of the chamber  522  and preferably comprises a plurality of annular injectors i.e.  507   a ,  507   b  and  507   c  vertically one above the other. Each annular injector is connected to a separate gas supply manifold. 
         [0039]    The annular gas discharge passage  503   b  surrounds the cylindrical lid support  502 . Preferably, a gas discharge ring  503  (not shown) is horizontally disposed in the cylindrical lid support  502  to retain a laminar flowing state of the gases before entering the exhaust port  509 . 
         [0040]    Preferably, the down surface of the lid  501  can be protected by attaching another sheet of plate (not shown) from direct deposition of the reactants during CVD processes. 
         [0041]    A method depositing crystalline layers on crystalline substrates using the CVD reactor chamber as shown in  FIG. 5  of one embodiment of this invention is set forth in the description which follows. One stream of gases mainly including the Group V reactant gases, i.e. NH 3 , another stream of gases mainly comprising the Group III reactant gases, i.e. TMGa, TMAI and TMIn, and another yet stream of gases mainly consisting of Ar, H 2 , N 2  or Group V reactant gases or their mixtures are horizontally injected respectively through the annular injectors  507   a ,  507   b  and  507   c  into the cylindrical chamber  522  in the inwardly radial direction. As shown in  FIG. 5 , a laminar flowing state can be retained in the entire chamber  522  until all the gases are evacuated in the annular gas discharge passage  503 . The depletion effect particularly related to the Group III reactants is inherently compensated by the converging gas flow in the inwardly radial direction. Uniform layers can be deposited without rotation of the wafers  500 , thus simplifying construction and reducing costs particularly related to the annular wafer carrier  506 . Referring to  FIG. 5 , the gas inlet ring  507  is horizontally disposed in the periphery of the chamber  522 , thus further simplifying construction, reducing costs, and easing routine operation particularly related to the lid  501 . A complete cleaning of the down surface of the lid  501  can be done routinely to ensure repeatability and reproducibility of CVD processes. The cylindrical lid support  502  mitigates deformation of the lid  501 , facilitating easy and economic scale-up of the cylindrical chamber size in diameter for a larger wafer capacity. 
         [0042]    According to another embodiment, as shown in  FIG. 6 , a CVD reactor can have a generally cylindrical chamber  622 . A generally cylindrical chamber  622  comprises a generally circular top plate, so as to be the lid  601 , a cylindrical lid support  602 , a gas injection plate  604 , an annular wafer carrier  606 , support tubes  640   a  and  640   b , a gas inlet ring  607 , an annular gas discharge ring  603 , a heat assembly  626 , and an exhaust port  609 . 
         [0043]    The cylindrical lid support  602  is preferred to be concentrically disposed in the center of a bottom plate  613  and provides an upper ridge whereon the central portion of the lid of the chamber  622  rests. 
         [0044]    The gas injection plate  604  at the top of the chamber  622  comprises a plurality of openings  619  regularly distributed in the down surface thereof, which can provide a vertical gas flow downwardly to the surface of the annular wafer carrier  606 . It is further preferred that the radial width of the annular zone having the openings  619  on the down surface  612  is broader than the radial width of the annular area where the wafers  600  are placed. 
         [0045]    The annular wafer carrier  606  is preferred to be horizontally disposed on the support tubes  640   a  and  640   b . The annular wafer carrier  606  comprises a plurality of pockets, each of which is configured to contain a wafer  600 . 
         [0046]    The gas inlet ring  607  is preferred to be horizontally disposed in the periphery of the chamber  622  and preferably comprises a plurality of annular injectors i.e.  607   a  and  607   b  vertically one above the other. Each annular injector is connected to a separate gas supply manifold. 
         [0047]    The annular gas discharge ring  603  is horizontally disposed in the cylindrical lid support  602  to retain a laminar flowing state of gases before entering the exhaust port  609 . For simplicity, the annular gas discharge ring  603  can be replaced by the annular gas discharge passage  603   b  (not shown) surrounding the cylindrical lid support  602 . 
         [0048]    A method depositing crystalline layers on crystalline substrates using the CVD reactor chamber as shown in  FIG. 6  of another embodiment of this invention is set forth in the description which follows. One stream of gases mainly including the Group V reactant gases, i.e. NH 3 , and another stream of gases mainly comprising the Group III reactant gases, i.e. TMGa, TMAI and TMIn, are horizontally injected respectively through the annular injectors  607   a  and  607   b  into the cylindrical chamber  622  in the inwardly radial direction. Another yet stream of gases mainly consisting of Ar, H 2 , N 2  or Group V reactant gases or Group III reactant gases or their mixtures is injected through the openings  619  of the gas injection plate  604  into the chamber  622  in the vertical direction. 
         [0049]    As shown in  FIG. 6 , the vertical gas flow is intended to cross substantially perpendicularly to the horizontal gas flow, so as to prevent the horizontal gases from upwardly penetrating. A laminar flowing state can be retained in the entire chamber  622  until all the gases are evacuated through the annular gas discharge ring  603 . The depletion effect particularly related to the Group III reactants is inherently compensated by the converging gas flow in the inwardly radial direction. Uniform layers can be deposited without rotation of the wafers  600 , thus simplifying construction and reducing costs particularly related to the annular wafer carrier  606 . The cylindrical lid support  602  mitigates deformation of the lid  601 , facilitating easy and economic scale-up of the cylindrical chamber size for a larger wafer capacity. 
         [0050]    A method depositing crystalline layers on crystalline substrates using the CVD reactor chamber as shown in  FIG. 6  of another yet embodiment of this invention is set forth in the description which follows. One stream of gases mainly including the Group V reactant gases, i.e. NH 3 , is horizontally injected through the annular injector  607   a  into the cylindrical chamber  622  in the inwardly radial direction. Another stream of gases mainly comprising the Group III reactant gases, i.e. TMGa, TMAI and TMIn, is injected through the openings  619  of the gas injection plate  604  into the chamber  622  in the vertical direction. 
         [0051]    The uniform distribution of the Group III reactants over the entire wafer carrier  606  can produce uniform deposition of layers on the wafers  600 . So, the wafers  600  are not necessary to be rotated, thus simplifying construction and reducing costs. The vertical gas flow can suppress thermal convection above heated wafers  600  to retain a laminar flowing state of the gases horizontally inwardly injected by the gas inlet ring  607  to the annular gas discharge ring  603 . The Group V and Group III reactant gases are completely separated before entering the chamber  622 . They are mixed immediately before reaching the surface of the wafers  600 , hence parasitic reactions only happen in a very short time, which substantially reduces the formation of particles and adducts in the gas phase. The cylindrical lid support  602  mitigates deformation of the lid  601 , facilitating easy and economic scale-up of the cylindrical chamber size for a larger wafer capacity. 
         [0052]    A method depositing crystalline layers on crystalline substrates using the CVD reactor chamber as shown in  FIG. 6  of another embodiment of this invention is set forth in the description which follows. One stream of gases mainly including the Group III reactant gases, i.e. TMGa, TMAI and TMIn, is horizontally injected through the annular injector  607   b  into the cylindrical chamber  622  in the inwardly radial direction. Another stream of gases mainly comprising the Group V reactant gases, i.e. NH 3 , is injected through the openings  619  of the gas injection plate  604  into the chamber  622  in the vertical direction. 
         [0053]    The depletion effect particularly related to the Group III reactants is inherently compensated by the converging gas flow in the inwardly radial direction. Uniform layers can be deposited without rotation of the wafers  600 , thus simplifying construction and reducing costs particularly related to the annular wafer carrier  606 . The vertical gas flow can suppress thermal convection above heated wafers  600  to retain a laminar flowing state of the gases horizontally inwardly injected by the gas inlet ring  607  to the annular gas discharge ring  603 . The Group V and Group III reactant gases are completely separated before entering the chamber  622 . They are mixed immediately before reaching the surface of the wafers  600 , hence parasitic reactions only happen in a very short time, which substantially reduces the formation of particles and adducts in the gas phase. The cylindrical lid support  602  mitigates deformation of the lid  601 , facilitating easy and economic scale-up of the cylindrical chamber size for a larger wafer capacity. 
         [0054]    According to another yet embodiment, as shown in  FIG. 7 , a CVD reactor can have a generally cylindrical chamber  722 . A generally cylindrical chamber  722  comprises a generally circular top plate, so as to be the lid  701 , a cylindrical lid support  702 , a gas injection plate  704 , an annular wafer carrier  706 , support tubes  740   a  and  740   b , a gas inlet ring  707 , an annular gas discharge passage  703   a , a heat assembly  726 , and an exhaust port  709 . 
         [0055]    The cylindrical lid support  702  is preferred to be concentrically disposed in the center of a bottom plate  713  and provides an upper ridge whereon the central portion of the lid of the chamber  722  rests. 
         [0056]    The gas injection plate  704  at the top of the chamber  722  comprises a plurality of openings  719  regularly distributed in the down surface thereof, which can provide a vertical gas flow downwardly to the surface of the annular wafer carrier  706 . It is further preferred that the radial width of the annular zone having the openings  719  on the down surface  712  is broader than the radial width of the annular area where the wafers  700  are placed. 
         [0057]    The annular wafer carrier  706  is preferred to be horizontally disposed on the support tubes  740   a  and  740   b . The annular wafer carrier  706  comprises a plurality of pockets, each of which is configured to contain a wafer  700 . 
         [0058]    The gas inlet ring  707  is preferred to be horizontally disposed in the cylindrical lid support  722  and preferably comprises a plurality of annular injectors i.e.  707   a  vertically one above the other. Each annular injector is connected to a separate gas supply manifold. 
         [0059]    The annular gas discharge passage  703   a  in the periphery of the chamber  722  surrounds the outer wall of the wafer carrier  706 . 
         [0060]    A method depositing crystalline layers on crystalline substrates using the CVD reactor chamber as shown in  FIG. 7  of one embodiment of this invention is set forth in the description which follows. One stream of gases mainly including the Group V reactant gases, i.e. NH 3 , is horizontally injected through the annular injector  707   a  into the cylindrical chamber  722  in the outwardly radial direction. Another stream of gases mainly comprising the Group III reactant gases, i.e. TMGa, TMAI and TMIn, is injected through the openings  719  of the gas injection plate  704  into the chamber  722  in the vertical direction. 
         [0061]    The uniform distribution of the Group III reactants over the entire wafer carrier  706  can produce uniform deposition of layers on the wafers  700 . So, the wafers are not necessary to be rotated, thus simplifying construction and reducing costs. The vertical gas flow can suppress thermal convection above heated wafers  700  to retain a laminar flowing state of the gases horizontally outwardly injected by the gas inlet ring  707  to the annular gas discharge passage  703   a . The Group V and Group III reactant gases are mixed immediately in close proximity to the up surface of annular wafer carrier  706 , hence parasitic reactions only happen in a very short time, which substantially reduces the formation of particles and adducts in the gas phase. The cylindrical lid support  702  mitigates deformation of the lid  701 , facilitating easy and economic scale-up of the cylindrical chamber size for a larger wafer capacity. 
         [0062]    According to another yet embodiment, as shown in  FIG. 8 , a CVD reactor can have a generally cylindrical chamber  822 . A generally cylindrical chamber  822  comprises a generally circular top plate, so as to be the lid  801 , a cylindrical lid support  802 , a gas injection plate  804 , an annular wafer carrier  806 , support tubes  840   a  and  840   b , an inner and outer annular gas discharge passage  803   b  and  803   a , a heat assembly  826 , and an exhaust port  809 . 
         [0063]    The cylindrical lid support  802  is preferred to be concentrically disposed in the center of a bottom plate  813  and provides an upper ridge whereon the central portion of the lid of the chamber  822  rests. 
         [0064]    The gas injection plate  804  at the top of the chamber  822  comprises two separate sets of a plurality of openings  819  regularly distributed in the down surface thereof, which can provide vertical gas flows downwardly to the surface of the annular wafer carrier  806 . Each set of the openings  819  is connected to a separate gas supply manifold. It is further preferred that the radial width of the annular zone having the openings  819  on the down surface  812  is broader than the radial width of the annular area where the wafers  800  are placed. 
         [0065]    The annular wafer carrier  806  is preferred to be horizontally disposed on the support tubes  840   a  and  840   b . The annular wafer carrier  806  comprises a plurality of pockets, each of which is configured to contain a wafer  800 . 
         [0066]    The inner annular gas discharge passage  803   b  surrounds the inner wall of the wafer carrier  806  and the outer annular gas discharge passage  803   a  surrounds the outer wall of the wafer carrier  806 . 
         [0067]    A method depositing crystalline layers on crystalline substrates using the CVD reactor chamber as shown in  FIG. 8  of one embodiment of this invention is set forth in the description which follows. One stream of gases mainly including the Group V reactant gases, i.e. NH 3 , and the other stream of gases mainly comprising the Group III reactant gases, i.e. TMGa, TMAI and TMIn, is separately injected through the corresponding set of the openings  819  in the gas injection plate  804  into the chamber  822  in the vertical direction. 
         [0068]    The uniform distribution of the Group III reactants over the entire wafer carrier  806  can produce uniform deposition of layers on the wafers  800 . So, the wafers  800  are not necessary to be rotated, thus simplifying construction and reducing costs. The vertical gas flow can suppress thermal convection above heated wafers  800  to retain a spreading laminar flowing state of the gases in the chamber  822 . The cylindrical lid support  802  mitigates deformation of the lid  801 , facilitating easy and economic scale-up of the cylindrical chamber size for a larger wafer capacity. 
         [0069]    According to another yet embodiment, as shown in  FIG. 9 , a CVD reactor can have a generally cylindrical chamber  922 . A generally cylindrical chamber  922  comprises a generally circular top plate, so as to be the lid  901 , a cylindrical lid support  902 , an annular gas distribution plate  904 , a gas injection ring  905 , an annular wafer carrier  906 , support tubes  940   a  and  940   b , a gas inlet ring  907 , an annular gas discharge passage  903   b , a heat assembly  926 , and an exhaust port  909 . 
         [0070]    The cylindrical lid support  902  is preferred to be concentrically disposed in the center of a bottom plate  913  and provides an upper ridge whereon the central portion of the lid of the chamber  922  rests. 
         [0071]    The annular gas distribution plate  904  having a plurality of through openings  919  arranged throughout the down surface thereof is horizontally disposed immediately below the lid of the chamber  922 , so as to define an upper compartment  920 . It is further preferred that the radial width of the annular zone having the openings  919  on the down surface  912  is broader than the radial width of the annular area where the wafers  900  are placed. The distance between the up surface of the annular gas distribution plate  904  and the down surface of the lid  901  is small enough to create a generally laminar flow of gases through the upper compartment  920 . 
         [0072]    The annular wafer carrier  906  is preferred to be horizontally disposed on the support tubes  940   a  and  940   b . The annular wafer carrier  906  comprises a plurality of pockets, each of which is configured to contain a wafer  900 . 
         [0073]    The gas injection ring  905  is horizontally disposed in the periphery of the chamber  922  vertically between the lid of the chamber  922  and the up surface of the gas distribution plate  904 . 
         [0074]    The gas inlet ring  907  is preferred to be horizontally disposed in the periphery of the chamber  922  vertically between the down surface of the gas distribution plate  904  and the up surface of the wafer carrier  906  and preferably comprises a plurality of annular injectors i.e.  907   a  and  907   b  vertically one above the other. Each annular injector is connected to a separate gas supply manifold. 
         [0075]    The annular gas passage  903   b  surrounds the cylindrical lid support  902 . It is preferable to have a gas discharge ring  903  (not shown) horizontally disposed in the cylindrical lid support  902 ; 
         [0076]    A method depositing crystalline layers on crystalline substrates using the CVD reactor chamber as shown in  FIG. 9  of one embodiment of this invention is set forth in the description which follows. One stream of gases mainly including the Group V reactant gases, i.e. NH 3 , the other stream of gases mainly comprising the Group III reactant gases, i.e. TMGa, TMAI and TMIn, are horizontally injected respectively through the annular injector  907   a  and  907   b  into the cylindrical chamber  922  in the inwardly radial direction. Another stream of gases mainly consisting of Ar, H 2 , N 2  or Group V reactant gases or Group III reactant gases or their mixtures, which are horizontally injected by the gas injection ring  905  into the upper compartment  920  in the inwardly radial direction, passing through the openings  919  are vertically straightened and therefore uniformly distribute downwardly over the surface of an entire wafer carrier  906 . 
         [0077]    The different densities and the great differences in the flow velocities of the gases horizontally entering the cylindrical chamber  922  produce an annular vortex underneath the down surface of the annular gas distribution plate  904 . A stream of gases vertically flowing downward through the openings  919  of the annular gas distribution plate  904  can prevent this vortex. As shown in  FIG. 9 , a laminar flowing state can be retained in the entire chamber  922  until all the gases are evacuated through the annular gas discharge passage  903   b . The depletion effect particularly related to the Group III reactants is inherently compensated by the converging gas flow in the inwardly radial direction. Uniform layers can be deposited without rotation of the wafers  900 , thus simplifying construction and reducing costs particularly related to the annular wafer carrier  906 . The cylindrical lid support  902  mitigates deformation of the lid  901 , facilitating easy and economic scale-up of the cylindrical chamber size for a larger wafer capacity. 
         [0078]    A method depositing crystalline layers on crystalline substrates using the CVD reactor chamber as shown in  FIG. 9  of another embodiment of this invention is set forth in the description which follows. One stream of gases mainly including the Group V reactant gases, i.e. NH 3 , is horizontally injected through the annular injector  907   a  into the cylindrical chamber  922  in the inwardly radial direction. Another stream of gases mainly comprising the Group III reactant gases, i.e. TMGa, TMAI and TMIn, which are horizontally injected by the gas injection ring  905  into the upper compartment  920  in the inwardly radial direction, passing through the openings  919  are vertically straightened and therefore uniformly distribute downwardly over the surface of an entire wafer carrier  906 . 
         [0079]    The uniform distribution of the Group III reactants over the entire wafer carrier  906  can produce uniform deposition of layers on the wafers  900 . So, the wafers  900  are not necessary to be rotated, thus simplifying construction and reducing costs. The vertical gas flow can suppress thermal convection above heated wafers  900  to retain a laminar flowing state of the gases horizontally inwardly injected by the gas inlet ring  907  to the annular gas discharge passage  903   b . The Group V and Group III reactant gases are mixed immediately before reaching the surface of the wafers  900 , hence parasitic reactions only happen in a very short time, which substantially reduces the formation of particles and adducts in the gas phase. The cylindrical lid support  902  mitigates deformation of the lid  901 , facilitating easy and economic scale-up of the cylindrical chamber size for a larger wafer capacity. 
         [0080]    A method depositing crystalline layers on crystalline substrates using the CVD reactor chamber as shown in  FIG. 9  of another yet embodiment of this invention is set forth in the description which follows. One stream of gases mainly including the Group III reactant gases, i.e. TMGa, TMAI and TMIn, is horizontally injected through the annular injector  907   b  into the cylindrical chamber  922  in the inwardly radial direction. Another stream of gases mainly comprising the Group V reactant gases, i.e. NH 3 , which are horizontally injected by the gas injection ring  905  into the upper compartment  920  in the inwardly radial direction, passing through the openings  919  are vertically straightened and therefore uniformly distribute downwardly over the surface of an entire wafer carrier  906 . 
         [0081]    The depletion effect particularly related to the Group III reactants is inherently compensated by the converging gas flow in the inwardly radial direction. Uniform layers can be deposited without rotation of the wafers  900 , thus simplifying construction and reducing costs particularly related to the annular wafer carrier  906 . The vertical gas flow can suppress thermal convection above heated wafers  900  to retain a laminar flowing state of the gases horizontally inwardly injected by the gas inlet ring  907  to the annular gas discharge passage  903   b . The Group V and Group III reactant gases are mixed immediately before reaching the surface of the wafers  900 , hence parasitic reactions only happen in a very short time, which substantially reduces the formation of particles and adducts in the gas phase. The cylindrical lid support  902  mitigates deformation of the lid  901 , facilitating easy and economic scale-up of the cylindrical chamber size for a larger wafer capacity. 
         [0082]    It is also preferable to have the gas injection ring  905  horizontally disposed in the cylindrical lid support  902  vertically between the lid of the chamber  922  and the up surface of the gas distribution plate  904 . In this case, the stream of the gases, which are horizontally injected by the gas injection ring  905  into the upper compartment  920  in the outwardly radial direction, passing through the openings  919  are vertically straightened and therefore uniformly distribute downwardly over the surface of an entire wafer carrier  906 . 
         [0083]    According to one embodiment, as shown in  FIG. 10 , a CVD reactor can have a generally cylindrical chamber  1022 . A generally cylindrical chamber  1022  comprises a generally circular top plate, so as to be the lid  1001 , a cylindrical lid support  1002 , an annular gas distribution plate  1004 , a gas injection ring  1005 , an annular wafer carrier  1006 , support tubes  1040   a  and  1040   b , a gas inlet ring  1007 , an annular gas discharge passage  1003   a , a heat assembly  1026 , and an exhaust port  1009 . 
         [0084]    The cylindrical lid support  1002  is preferred to be concentrically disposed in the center of a bottom plate  1013  and provides an upper ridge whereon the central portion of the lid of the chamber  1022  rests. 
         [0085]    The annular gas distribution plate  1004  having a plurality of through openings  1019  arranged throughout the down surface thereof is horizontally disposed immediately below the lid of the chamber  1022 , so as to define an upper compartment  1020 . It is further preferred that the radial width of the annular zone having the openings  1019  on the down surface  1012  is broader than the radial width of the annular area where the wafers  1000  are placed. The distance between the up surface of the annular gas distribution plate  1004  and the down surface of the lid  1001  is small enough to create a generally laminar flow of gases through the upper compartment  1020 . 
         [0086]    The annular wafer carrier  1006  is preferred to be horizontally disposed on the support tubes  1040   a  and  1040   b . The annular wafer carrier  1006  comprises a plurality of pockets, each of which is configured to contain a wafer  1000 . 
         [0087]    The gas injection ring  1005  is horizontally disposed in the periphery of the chamber  1022  vertically between the lid of the chamber  1022  and the up surface of the gas distribution plate  1004 . 
         [0088]    The gas inlet ring  1007  is preferred to be horizontally disposed in the cylindrical lid support  1002  vertically between the down surface of the gas distribution plate  1004  and the up surface of the wafer carrier  1006  and preferably comprises a plurality of annular injectors i.e.  1007   a  vertically one above the other. Each annular injector is connected to a separate gas supply manifold. 
         [0089]    The annular gas passage  1003   a  surrounds the outer wall of the annular wafer carrier  1006  in the periphery of the chamber  1022 . It is preferable to have a gas discharge ring  1003  (not shown) horizontally disposed in the side wall  1011  of the chamber  1022 . 
         [0090]    A method depositing crystalline layers on crystalline substrates using the CVD reactor chamber as shown in  FIG. 10  of one embodiment of this invention is set forth in the description which follows. One stream of gases mainly including the Group V reactant gases, i.e. NH 3 , is horizontally injected through the annular injector  1007   a  into the cylindrical chamber  1022  in the outwardly radial direction. Another stream of gases mainly comprising the Group III reactant gases, i.e. TMGa, TMAI and TMIn, which are horizontally injected by the gas injection ring  1005  into the upper compartment  1020  in the inwardly radial direction, passing through the openings  1019  are vertically straightened and therefore uniformly distribute downwardly over the surface of an entire wafer carrier  1006 . 
         [0091]    The uniform distribution of the Group III reactants over the entire wafer carrier  1006  can produce uniform deposition of layers on the wafers  1000 . So, the wafers  1000  are not necessary to be rotated, thus simplifying construction and reducing costs. The vertical gas flow can suppress thermal convection above heated wafers  1000  to retain a laminar flowing state of the gases horizontally outwardly injected by the gas inlet ring  1007  to the annular gas discharge passage  1003   a . The Group V and Group III reactant gases are mixed immediately before reaching the surface of the wafers  1000 , hence parasitic reactions only happen in a very short time, which substantially reduces the formation of particles and adducts in the gas phase. The cylindrical lid support  1002  mitigates deformation of the lid  1001 , facilitating easy and economic scale-up of the cylindrical chamber size for a larger wafer capacity. 
         [0092]    It is also preferable to have the gas injection ring  1005  horizontally disposed in the cylindrical lid support  1002  vertically between the lid of the chamber  1022  and the up surface of the gas distribution plate  1004 . In this case, the stream of the gases, which are horizontally injected by the gas injection ring  1005  into the upper compartment  1020  in the outwardly radial direction, passing through the openings  1019  are vertically straightened and therefore uniformly distribute downwardly over the surface of an entire wafer carrier  1006 . 
         [0093]    The CVD chamber of this invention can provide a cylindrical lid support. Complexities and costs to building a large size chamber as well as difficulties and costs to maintain a large size chamber can be substantially mitigated. The CVD chamber of this invention can have a gas distribution plate, which can provide a vertical flow to retain a horizontal laminar flow of gases in the radial direction. The repeatability, reproducibility and consistency of chemical vapor deposition processes and uniformity of deposited layers at reduced consumption of reactants can be achieved. 
         [0094]    It is understood that the exemplary method and apparatus for chemical vapor deposition described herein and shown in the drawings represents only presently preferred embodiments of the invention. Indeed, various modifications and additions may be made to such embodiments without departing from the spirit and scope of the invention. For example, it should be appreciated that the apparatus and method of the present invention may find applications which are different from chemical vapor deposition.