KR20040083417A - Chemical vapor deposition reactor - Google Patents

Abstract

Chemical Vapor Deposition (CVD) reactor 900 includes a reactor chamber 950, a substrate holder 46 located within the reactor chamber, a gas inlet system 922 disposed to provide a rotating gas flow over the substrate holder, and a gas. An outlet port 930. The flow feature of the precursor gas is controlled to make the film thickness uniform across the substrate surface by forcing the gas to a smaller volume as the precursor gas moves across the substrate. With a central exhaust, this is done by decreasing the heights 1506 and 1524 of the reactor chamber as it approaches the center 1508 of the reactor chamber, such that the reactor volume per unit distance is reduced as the gas moves from the inlet to the exhaust. .

Description

Chemical Vapor Deposition and Chemical Vapor Deposition Reactor {CHEMICAL VAPOR DEPOSITION REACTOR}

CVD is a common method for depositing thin films of complex compounds such as metal oxides, ferroelectrics, superconductors, materials with high dielectric constants, gemstones, and the like. Existing methods of chemical vapor deposition that provide a good range of steps typically result in relatively low integrated circuit yields when used to deposit composite materials. In the prior art CVD methods, one or more liquid or solid precursors are converted to a gaseous state. In order to gasify a sufficient amount of precursor at a commercially viable rate, it is usually necessary to heat the precursor. However, the precursor is typically physically unstable at the higher temperatures necessary to achieve sufficient mass transfer of the precursor from the liquid or solid phase to the gas phase. This physical instability itself may indicate premature boiling of the precursor solvent. Thus, the precursor compound typically experiences separation, degradation or precipitation. Premature separation is an instrument that is affected by causing undesirable and uncontrolled changes in the stoichiometry of the process stream and the final product, uneven adhesion of the substrate in the CVD reactor, and contamination of the CVD apparatus. Stopping the CVD instrument operation to clean up will result in cost and significant inconvenience. In addition, the particulate material falls down onto the wafer resulting in defective devices and low yields. In addition, since early decomposition of the precursor reactants does not occur uniformly for all components of the precursors, imbalance removal of the selected reactants from the gas precursors results in an altered stoichiometry of the remaining gas precursors. This results in the formation of an ineffective chemical composition on the surface of the wafer.

Another problem with existing CVD systems is the incomplete gasification of the precursors. If one or more precursors fail to properly gasify in a device that is guided to the attachment chamber, one or more precursors may be deposited on the substrate without properly reacting with other precursors in the CVD apparatus. This is due to the independent growth between specific precursors. Such improper attachment may result in the disposal of unreacted precursor material and may cause malfunction of the circuit in which this attachment is made.

One conventional method for wafer processing is to use a showerhead gas dispenser located on a heated rotating substrate in a CVD reactor. The substrate is generally rotated to provide a substantially uniform boundary layer under a free flowing gas that provides substantially uniform reactant concentration on the substrate. Showerheads are useful for high temperature processes, but employ showerhead designs that involve the attachment of heavy molecules such as those used in the formation of strontium bismuth titanate (SBT) and other layered superlattice materials. In that case problems arise. Such layered regular lattice material precursors typically have low vapor pressures and correspondingly high vaporization temperatures. However, layered regular lattice material precursors typically have a low decomposition temperature, thereby overly suppressing depending on the required ambient temperature range required for the CVD reactor. High vaporization temperatures typically lead to premature decomposition of the layered regular lattice material which leads to the problems outlined above. In order to avoid these problems, if the temperature is lowered, incomplete gasification may occur due to solvent boiling off and precipitation.

One conventional method involves the use of modified heavy molecular precursors in combination with existing CVD apparatus. The theory is that precursors modified to exhibit high component vapor pressures eliminate the need for high vaporization temperatures in the CVD process, thereby avoiding the problem of precipitation and premature decomposition. However, precursors obtained with high vapor pressure have poor properties for growing layers on the wafer, one of which is poor adhesion rate.

Therefore, there is a need in the art for CVD systems and methods that can securely attach SBT and other heavy or complex molecules onto a wafer without causing problems of premature degradation and incomplete gasification.

Summary of the Invention

The present invention advances the prior art by introducing a precursor gas into the reactor chamber, circulating the precursor gas over the substrate, and growing a layer of material on the surface of the substrate at a substantially uniform rate over the surface of the substrate and It helps to solve the above problems. The shape of the reactor plays an important role. In a preferred embodiment, the gas is shaped such that the precursor gas is forced to a smaller volume when the gas is reduced.

In one embodiment, the CVD reactor comprises SBT and / or other metal oxide molecules on the wafer, permits the flow of gas precursors with a controlled boundary layer thickness, and facilitates the growth of material on the surface of the wafer. This allows the ratio to be substantially constant. Preferably, the described deposition is accomplished without premature decomposition of the gas precursor flowing onto the wafer or substrate and precipitation of particulate matter from the gas precursor. Although the above description discloses the suitability of CVD reactors for use in precursors including SBT and other metal oxide molecules, the CVD reactors described herein may be used in a wide range of precursors and reactants including silicon.

In one embodiment, the precursor gas is introduced into the CVD reactor at the periphery of the reactor chamber and in a direction that is substantially tangential to the chamber circumference, thereby advantageously creating a spinning field of the precursor gas on the stationary substrate. Occurs. This method eliminates the need for a showerhead dispenser in a conventional CVD system and the problem of particulate material formation attached to the system. Using a fixed substrate is advantageous in reactor design by eliminating the need for a mechanism to rotate the substrate and enabling early measurement of the substrate temperature. In the prior art, such temperature measurement is complicated by the necessity of measuring the temperature with a pyrometer and by using the telemeter method and connecting the temperature measuring lead out of the rotating mechanism.

In one embodiment, one or more tubes orient the precursor gas into a conduit disposed about the circumference of the reactor chamber. Preferably, one or more channels exiting the circumferential conduit direct the precursor gas into the reactor chamber along a direction substantially tangential to the circumference of the reactor chamber. Preferably, the inlet is located at the chamber end of each channel. It is preferred that the opening is substantially positioned in the center of the reactor chamber to exhaust the precursor gas. This method provides a uniform gas flow along the inner circumference of the reactor. In one embodiment, the height of the reactor chamber including the precursor gas stream is substantially proportionally reduced with decreasing radial distance from the center of the reactor gas stream. Thus, two factors tend to increase the gas flow rate towards the center of the reactor chamber. First, preservation of the angular momentum requires that the gas linear velocity be increased when the radial distance of the gas flow from the chamber center is reduced. Second, decreasing chamber height reduces the cross-sectional area of the gas flow towards the center of the chamber, whereby it is necessary to increase the linear gas flow rate to maintain a constant mass flow rate. Preferably, the increase in gas flow rate is led to a reduced flow boundary layer thickness towards the center of the chamber, which leads to increased overall exposure of the reactants through gas diffusion into the substrate towards the center of the chamber. Preferably, increased exposure of the reactant with decreasing radial distance compensates for the increasing decrease in precursor gas reactant that occurs when the precursor gas flows onto the substrate toward the center. Preferably, accurate compensation of reactant reduction with increased reactant diffusion allows for substantially uniform film growth on the substrate surface. While the above description has been made with respect to reactor chambers that are primarily circular in the horizontal plane, the reactor chambers are not limited to circular or horizontal geometry, and may take a wide variety of shapes and / or poses.

The present invention provides a reactor chamber comprising a substrate holder defining a substrate plane, through which the precursor gas is directed substantially in the direction of the gas inlet to the exhaust port and in the substrate plane. Moving in a circular motion about an orthogonal axis, reducing the reactor volume per unit distance used for the precursor gas as the precursor gas moves in the direction, and activating vapor on the surface of the substrate A chemical vapor deposition method is provided, comprising attaching a solid thin film. Preferably, said moving step comprises providing a helical movement. Advantageously, said moving step comprises increasing the velocity of said precursor gas as said precursor gas approaches the center of said reactor chamber. Advantageously, said moving step comprises controlling the flow characteristics of said moved precursor gas to compensate for the reduction of reactants in said moved precursor gas. Preferably, the moving step comprises controlling the flow specification of the moved precursor gas to make the film thickness across the substrate surface substantially the same. Advantageously, the moving step comprises reducing the boundary layer thickness of the gas precursor flow on the substrate surface as it approaches the center of the reactor chamber. Preferably, the step of moving comprises increasing the diffusion rate of reactant from the precursor gas to the substrate surface as it nears the center of the reactor chamber. Preferably, said reactor chamber providing step comprises providing a substantially circular reactor chamber, said direction being substantially radially inward. Advantageously, said reducing step comprises reducing the height of said reactor chamber as it approaches a center of said reactor chamber. Preferably, the substrate is held substantially fixed. Maintaining the temperature of the reactor chamber below the decomposition temperature of the precursor gas. The holding step includes maintaining the temperature of the side wall of the reactor chamber at substantially 200 ° C. Preferably, the holding step includes maintaining the temperature of the precursor gas at substantially 200 ° C. Preferably, the method further comprises maintaining the pressure in the reactor chamber to 10 Torr (1333 Newtons per square meter) or less. More preferably, the method further comprises maintaining the pressure in the reactor chamber at substantially 1 Torr (1333 Newtons per square meter). The method preferably further comprises maintaining a temperature of the substrate between 320 ° C and 360 ° C. Most preferably, the method further comprises maintaining the temperature of the substrate at substantially 340 ° C.

The present invention also includes a reactor chamber, a substrate holder located within the reactor chamber and defining a substrate plane, a gas inlet system comprising a gas inlet, and a gas outlet port, wherein the reactor chamber is provided per unit distance. A reactor chamber is provided that is configured to decrease in direction from the gas inlet to the gas outlet port. Preferably, the reactor chamber comprises a circular wall and the gas inlet system comprises a gas inlet oriented substantially tangentially to the circular wall. Preferably, the reactor chamber is substantially circular and the direction is radially inward. Preferably, the reactor comprises an upper wall and the height of the reactor chamber upper wall above the substrate holder is increased as the distance from the center of the chamber is increased. Preferably, the height of the chamber upper wall above the substrate holder is changed substantially linearly by a distance from the center of the chamber. Preferably, the reactor comprises a top wall, wherein the height of the reactor chamber top wall above the substrate is a function of the rate of reactant reduction in the chamber. Preferably, the reactor comprises an upper wall and the height of the reactor chamber upper wall above the substrate is varied in radial position to compensate for the rate of reactant reduction during gas flow through the chamber. Preferably, the reactor comprises an upper wall and the shape of the chamber is designed to provide a substantially uniform film growth rate on a substrate located on the substrate holder. Preferably, the substrate holder is substantially secured in the reactor such that the substrate holder is substantially secured. Preferably the substrate holder comprises a heater. Advantageously, said gas inlet system comprises a plurality of channels through said reactor chamber. Preferably, the channel is oriented substantially tangentially to the side wall of the reactor chamber. Preferably, the inlet is at the periphery of the reactor chamber. Advantageously, said gas inlet system, said reactor chamber, and said gas exhaust port cooperate to provide a helical gas flow over said substrate holder from the interior periphery of said chamber to said gas exhaust port. Preferably, the exhaust port is substantially centered in the reactor. Preferably, the chamber comprises an upper wall, at the periphery of the chamber, the upper wall is about 10 cm or less above the height of the substrate plane and near the exhaust port, wherein the upper wall is the height of the substrate plane. It is higher than 5cm or less. Preferably,

Wherein the chamber comprises an upper wall, at the periphery of the chamber the upper wall is 5 cm or less above the substrate plane and near the exhaust port, and the top wall is 2.5 cm above the substrate plane. Or higher.

Thus, although described in the above embodiments and important embodiments and features thereof have been described, the main purpose of the preferred embodiments is to provide a vortex-based CVD reactor that provides uniform adhesion of the precursor on the substrate. These and other advantages of the present invention can be better understood by reading the following detailed description of the invention taken in conjunction with the drawings.

The present invention relates generally to chemical vapor deposition (CVD) reactors, and more particularly to CVD reactors that provide the desired vapor phase stoichiometry and effective substrate range.

1 is a perspective view of a vortex-based CVD reactor according to the present invention,

2 is a cross-sectional view of the vortex-based CVD reactor taken along line 2-2 of FIG.

3 is a plan view of the base of the reactor of FIG. 1;

4 is a perspective view of the reactor base of FIG.

FIG. 5 is a cross-sectional view of the vortex-based CVD reactor of FIG. 1 showing a spinning gas system within the reactor; FIG.

FIG. 6 is a plan view of the vortex-based CVD reactor of FIG. 1, illustrating a spinning gas system within the reactor; FIG.

FIG. 7 shows the flow of gas simulated using the correct dimensions, gas type and temperature through the reactor of FIG. 1, FIG.

8 is a plan view of the rotating gas system of FIG. 7 in the plane of the substrate, showing good homogeneity of the helical gas;

9 is a side sectional view of a portion of a reactor according to a preferred embodiment of the present invention coupled to a vaporizer;

10 is a cross-sectional side view of a portion of the reactor of FIG. 9 showing a reactor housing;

11 is a side cross-sectional view of a portion of the reactor of FIG. 9 showing a main exhaust connection;

12 is a perspective view of a portion of the reactor of FIG. 9 showing a number of channels;

FIG. 13 is an enlarged perspective view of a portion of the conduit forming portion of the reactor of FIG. 9;

14 is a front sectional view of a portion of the conduit of the reactor of FIG. 9;

FIG. 15 is an enlarged side sectional view of a portion of the reactor chamber shown in FIG. 9; FIG.

In this specification, the term “mist” is defined as fine droplets or particles of liquid and / or solids carried by a gas. The term "mist" includes an aerosol, which is generally defined as a colloidal suspension of solid or liquid particles in a gas. The term “mist” also includes fog of precursor solutions in gases as well as other sprayed suspensions. Since the above and other terms used in suspensions in gases are used publicly, the provisions are not precise or redundant and may be used differently by different authors. Generally, the term “aerosol” is the text “Aerosol Science and Technology” written by Parker C. Reist, McGraw-Hill, Inc., New York, USA, in 1983. Science and Technology "is intended to include all suspensions included in " The term "mist" as used herein is considered in a broader sense than the term "aerosol" and includes a suspension that may not be included in the term "aerosol" or "fog". The term "mist" can be distinguished from gaseous liquids, ie gases. It is an object of the present invention to use venturi to generate mist from a liquid precursor mixture, with the resulting precursor mist droplets having an average diameter in the range of less than 1 micron, preferably in the range of 0.2 microns to 0.5 microns.

The terms "atomize" and "nebulize" are used interchangeably in the conventional sense to produce a spray or mist when applied to a liquid, ie to produce a suspension of liquid droplets in the gas. The term "vapor" means a gas of a species at a temperature below its critical temperature. The terms "vaporize", "vaporization", "gasify" and "gasification" are used interchangeably herein.

In a typical CVD process, the reagents needed to form the desired material are typically made of a liquid precursor solution, the precursors are vaporized (ie, gasified), and the vaporized reagents are fed into an attachment reactor containing a substrate, The material decomposes to form a thin film of the desired material on the substrate. In addition, the reagent vapor may be formed from a gas and a solid heated to form the vapor by sublimation.

The term "thin film" is used as it is used in integrated circuit technology. By thin film is meant a film that is less than 1 micron thick. In this specification, the thin film is 0.5 microns or less in thickness in all situations. Preferably, the film formed by the CVD apparatus described herein is 300 nm thick or less, most preferably 200 nm thick or less. Films of 20 nm to 100 nm are made routinely in the device according to the invention. These thin films of integrated circuit technology should not be confused with thin coatings or films in so-called "thin film capacitors". The term "thin" is used to describe such coatings and films, which are "thin" only for materials that are visible to the naked eye, and are generally tens and even hundreds of microns thick. Non-uniformity in such "thin" coatings is much greater than the total thickness of the thin film in the present specification; The process by which coatings and films are thus made is considered by those skilled in integrated circuit technology to be incompatible with integrated circuit technology.

In sentences, there is often some mismatched use of terms such as "reagent", "reactant" and "precursor". As used herein, the term "reagent" will generally be used to refer to a species or derivative thereof that reacts in an attachment reactor to form the desired thin film. Thus, in the present application, "reagent" may mean a metal-containing compound contained in, for example, a precursor, a vapor of the compound, or an oxidizing gas. The term “precursor” refers to the specific formula used in the CVD method that includes the reactants. For example, the precursor may be a pure reactant in solid or liquid or gas form. Typically, the liquid precursor is a liquid solution of one or more reactants in a solvent. The precursors can be combined to form other precursors. In this specification, the initial precursor used to form such a combination is the precursor component and generally the resulting combination is a precursor mixture. In general, the precursor liquid is an alkosilicate, sometimes referred to as sol-gel formulations, a carboxylate, sometimes referred to as a MOD formation, an alkoxycarboxylate, sometimes referred to as an EMOD formation, and other formations. Metal components in solvents such as metal-organic precursor formations comprising water. Typically, metal-organic formations for MOCVD include metal alkyls, metal-alcoholates, beta-diketonates, combinations thereof as well as many other precursor formations. In one embodiment, multi-metal polyalcoholates may be used. MOD formations can be formed by reacting a carboxylic acid, such as 2-ethylhexanoic acid, with a metal or metal component in the solvent. Solvents that may be used in any of the above formations are methyl ethyl ketone, isopropanol, methanol, tetrahydrofuran, xylene, n-butyl acetate, hexamethyl-disilazane (HMDS), octane, 2-methoxyethanol And ethanol. Initiators such as methyl ethyl ketone (MEK) can be added. A more extensive list of solvents and initiators, as well as specific examples of metal components, is US Pat. No. 6,056,994, entitled "Liquid Vapor Deposition for Manufacturing Layered Regular Grid Materials," issued to Paz de Araujo et al. On May 2, 2000; The name is "Method for Making Barium Strontium Titanium" and is disclosed in US Pat. No. 5,614,252, issued March 25, 1997 to McMillan et al.

As used herein, “gasified” precursor refers to the gaseous form of all compositions previously contained in liquid precursors such as, for example, vaporized reactants and vaporized solvents. The term "gasified precursor" refers to the gasified form of a single precursor or gas phase mixture of multiple precursors. In the present application, the terms "reactant" and "reactant gas" refer to the substrate plate in the attachment reactor even though the mixture logically includes other species such as vaporized solvent and non-reactive carrier gas. It refers to the gas phase mixture included in the adhesion reaction generated.

Preferably, the liquid precursor contains multi-metal polyalcoholide reactants, in particular to reduce the total number of liquid precursors that are misted, mixed and gasified. Nevertheless, the use of single-metal polyalcoholide precursors is fully consistent with the methods and apparatus of the present invention. In addition, all polyalcoholates are "alcoholates". Multi-metal polyalcoholates are included within the terms "metal alkoxides" and "metal polyalcoholates". Thus, the terms "polyalcosidate", "metal polyalcosidate" and "multi-metal polyalcosidate" have been used somewhat interchangeably in the present application, but the meaning in a specific context is clear.

The term "premature decomposition" in this application refers to all decomposition of reactants that do not occur in a heated substrate. Thus, early decomposition involves chemical decomposition of the reactants at various stages of the vaporizer and in the attachment reactor itself unless it is on a heated substrate. It is desirable to avoid "substantially premature degradation" because some premature degradation is known from the techniques of thermodynamics and chemical reaction kinetics that can occur almost certainly inevitably in some range even under optimal operating conditions. Substantially premature degradation is caused if premature degradation causes the formation of particles of solid material on the substrate at the location of a continuous, uniform thin film of solid material. In addition, substantial premature degradation occurs if premature degradation causes contamination of the CVD device, causing the need for more than one stop and cleaning of the device per 100 wafer processing.

As used herein, a "conduit" is a tube, pipe or other device for receiving a fluid flow. The conduits can receive liquid, mist or gas flows. As used herein, a “thermal barrier” is one that blocks heat transfer between different parts of a vaporizer. A "thermal insulator" is part of a thermal insulation including a solid material that thermally insulates, but gas or liquid insulators may be used. Insulation may include an air gap.

1 is a perspective view of a vortex-based CVD (chemical vapor deposition) reactor, also referred to as a CVD reactor 10. The component shown in FIG. 1 is a circular reactor base 12 and a circular sidewall located on the reactor base 12 and fitted and fixed to the reactor base 12 by a plurality of clamps 16a-16n. 14, a circular reactor top 18 positioned on the reactor side wall 14 and fitted and fixed to the reactor side wall 14 by a plurality of instrument assemblies 20a to 20n, and to the reactor top 18; A plurality of injector tubes 22a-22n fixed in tangential direction and extending through this top 18 and in communication with reactor interior 24 (FIG. 2), and in communication with reactor interior 24 and reactor top 18 ), A rectangular reactor base extension 28 extending outward from the reactor base 12 and having a flange 30, in communication with the reactor interior 24 and having a rectangular reactor. A robot arm access port 32 located at the center of the base extension 28.

FIG. 2 is a cross-sectional view of the vortex-based CVD reactor 10 taken along line 2-2 of FIG. 1, with all references previously described correspond to the elements previously described. Cavity 34 incorporates a variety of components, most of which are shown as now described in FIGS. 3 and 4. Attachment ring 36 seals against bottom planar region 38 of reactor base 12 by using O-ring 40 and a number of mechanical screws 42a through 42n. The connecting support collar 44 extends vertically through the lower planar region 38 of the reactor base 12 and through the attachment ring 36 to support the resistance heated chuck 46. The removable densified carbon susceptor 48 evenly transfers heat to the wafer substrate 50 in intimate contact with the resistance heated chuck 46. The lift yoke 52, which is operated vertically by the air cylinder lift arm 54, is aligned with sufficient clearance about the connecting support collar 44. A plurality of upwardly oriented ceramic repeat pins 56a-56n are secured to the lift yoke 52 and each of the plurality of mutually aligned body holes 58a in the heated chuck 46 and densified carbon susceptor 48. To 58n) and 60a to 60n. The top of the ceramic lift pins 56a-56n may extend beyond the top surface of the densified carbon susceptor 48 when the lift yoke 52 is operated up to its top movement.

Preferably, lift pins 56a to 56n, preferably made of ceramic material, support wafer substrate 50 for both processing and robot handling. The lift yoke 52 is shown in its lowest position, whereby the wafer substrate 50 can be in intimate contact with the susceptor 48, which is preferably made of densified carbon. Also, a liftable shutter 62 is attached to the lift yoke 52 as shown in FIGS. 3 and 4. Preferably, the shutter 62 is formed to conform to the shape of the lower region of the reactor base 12 to assist in providing a reactor interior 24 of uniformly smooth shape. Multiply angled brackets (64, 66) are securely fixed to the lift yoke (52) and located in the channels (68, 70) (FIG. 3) in the lower region of the reactor base (12), It is attached to a positionable shutter 62 and provides support to the shutter 62. Plates 72 and 74 are secured on and about channels 68 and 70 to limit the upward movement of the multilayered angled bracket 64 and correspondingly of the shutter 62 in the open mode. Restrict upward movement. For robot handling, the lift yoke 52 is moved upwards to position the lift pins 56a to 56n on the upper surface of the susceptor 48, thereby raising the substrate 50 to the raised position 50a. Move to. At the same time, the shutter 62 is moved to the raised position 62a to allow access to the reactor interior 24 by robot means entering through the robot arm access port 32. For insertion of the wafer substrate, the lift yoke 52, including the shutter 62 and lift pins 56a to 56n, is positioned in its fully upward position, thereby extending the ceramic lift pins 56a to 56n from which the robot handling mechanism is extended. A wafer substrate is attached. Next, the lift yoke 52 is lowered to attach the wafer substrate on the susceptor 48, and the shutter 62 is closed.

Preferably, thermocouple 76 is positioned in chuck 46 and heated to the sample and control temperature of chuck 46 and susceptor 48 during the attachment process. Heater 78, which is preferably a resistance heater, surrounds reactor sidewall 14. Also shown is a flange 80 at the upper edge of the reactor base 12, which seals with the O-ring 82 to the lower flange 84 of the reactor side wall 14. The upper flange 86 together with the o-ring 88 seals against a flange 90 located at the reactor top 18.

3 is a plan view of reactor base 12, with all reference numbers corresponding to previously disclosed elements. In particular, as described above, the relationship between the lift yoke 52 and the attached shutter 62 and the reactor base 12 is particularly shown.

4 is a perspective view of the reactor base 12, with all reference numbers corresponding to the above mentioned elements. Lift yoke 52 is shown upwardly positioned by air cylinder lift arm 54 to accommodate the position of substrate 50, such as a robot handling mechanism. Further, the shutter 62 attached by the positioning of the lift yoke 52 is positioned upward by the multilayer angled brackets 64 and 66 (not shown), whereby the robot mechanism allows the wafer substrate 52 to be positioned. The interior of the CVD reactor 10 can be accessed through the robot arm access port 32 to locate or retrieve).

The operation mode is described below. FIG. 5 is a cross-sectional view of a vortex-based CVD reactor 10 showing the spinning gas system 92 in the reactor interior 24, wherein all of the references above correspond to the aforementioned elements. Chemical vapor is introduced simultaneously through the injector tubes 22a through 22n into the reactor interior 24 at a sufficient pressure and at a suitable temperature. Preferably, chemical vapor 94 is dissipated from injector tubes 22a to 22n and produces a spinning gas system. For the sake of simplicity, only spinning gas system 92 is shown, which is dissipated from and generated by injector tube 22a, in which multiple complementary spinning gas systems are similarly dissipated from the remaining injector tubes 22b to 22n. It should be understood that this is produced. Preferably, the orientation of the injector tubes 22a-22n is such that the spinning gas system 92 comprising chemical vapor 94 is tangentially oriented with respect to the inner wall of the reactor side wall 14. The rotating gas system is moved downwards due to the reduced diameter of the reactor (ie lower pressure region). The downward spiral gas strikes the lower surface and the substrate and drags the object. The drop in speed from the drag causes gas to flow inward and upward with lower pressure. Thus, the gas moves upwards spirally out of the reactor outlet. Preservation of the angular momentum maintains helical direction and low turbulence continuity. Reference is made to FIG. 7, which is a side view, and FIG. 8, which is a plan view from the substrate plane.

FIG. 6 is a plan view of the vortex-based CVD reactor 10, while the reactor top 18 is not shown for simplicity, while the injector tubes 22a through 22n are inside the reactor 24 of the CVD reactor 10. FIG. It is shown in the image. As shown in FIG. 5 and for the sake of simplicity, only the spinning gas system 92 which is dissipated from and produced by one injector tube 22a is shown, which allows multiple complementary spinning gas systems to remain in a similar fashion. It should be understood that it is dissipated from and generated by the injector tubes 22b to 22n. All reference numerals correspond to those described above. As shown in FIG. 6, the gas differs in the kinetic component in the circular direction and in the direction d from the end of the inlet 63 of the injector tube 22c to the exhaust port 26 (FIG. 5). Spiral inward with components. There is also a motion component in the vertical direction in FIG. Similarly, gas from each of the other inlets has three kinetic components.

7 shows a fluid simulation of the proposed vortex CVD reactor. FIG. 8 shows a simulation showing gas motion in the plane of a spirally moving substrate with low gas turbulence. The mathematical description is disclosed in "Schlicting-Boundary Layer Theory" (hereinafter referred to as "Schlicting") for rotating gas systems on flat surfaces. "Schlicting" discloses a uniform boundary layer and relates to the simulation shown in FIG. In "Shilting", the boundary layer of gas is proportional to the square root of (V / W), V is velocity and W is rotational velocity (also known as angular frequency and angular velocity). In the embodiment of FIGS. 1-6, the boundary layer thickness generally does not change with the radial position in reactor 10.

9 is a side cross-sectional view of the vaporizer 100 connected to the reactor 900. Most of the difference between reactor 900 and reactor 10 is in line 906 that separates reactor top 952 and reactor base 958. First, the difference between the reactor base 958 and the reactor base 12 of the reactor 10 will be described. Shutter 908 is shown under heated chuck 46. Preferably, the shutter 908 cooperates with the bent shutter 1112 (FIG. 11) to provide an opening that allows the robot to access the substrate 50 at the appropriate time.

One preferred heater for use in the thermally controlled reactor 900 is a mica heater. However, as described below for the heaters, various different types of heaters may be used that may or may not be in physical contact with the reactor 900 surface. Moreover, other forms of thermal control may replace the heater. For example, in alternative embodiments of reactor 900, a cooling device may replace one or more heaters, and it is desired that the temperature of a selected portion of reactor 900 be cooled for the selected process. In this embodiment, the heater 946 is connected to the reactor base 958. Preferably, the heater 912 is connected to the downward facing surface of the reactor base extension 28. Preferably, the heater 914 is connected to the outer vertical wall of the reactor base extension 28.

The reactor top 952 will now be described. Vaporizer 100 is shown at the top of FIG. 9. The vaporizer 100 is named " Chemical Vaporizer Vaporizer " and is disclosed in detail in Applicant's U.S. Patent Application No. 60 / 337,637, filed December 4, 2001, the description of which is omitted herein. Preferably, vaporizer 100 is connected to reactor 900 at reactor connector interface 926. The remainder of the description of FIG. 9 relates to three main groups of components: gas inlet system 922, reactor chamber 950 and exhaust port 928.

Preferably, gas inlet system 922 includes reactor inlet 924, tube 938, conduit 940, channel 968, and inlet 942 at the inner (chamber) end of channel 968. . Preferably, the exhaust outlet 928 includes an exhaust port 930, an exhaust tube 932 and an exhaust tube flange 934. In this embodiment, a number of tubes 938 are connected to reactor inlet 924 and preferably direct gas into conduit 940 disposed circumferentially about reactor chamber 950. Although only one conduit is shown in FIG. 9, two or more conduits may be used in reactor 900. In this embodiment, six tubes 938 are used to direct the gas into the conduit 940. However, fewer or more than six tubes may be used.

In this embodiment, 18 channels 968 equally spaced about the circumference of reactor chamber 950 direct gas from conduit 940 into reactor chamber 950 via inlet 942. Less than or more than 18 channels 968 and inlets 942 may be used for reactor 900. Preferably, precursor gas 954 exits the inlet 942 and flows on the substrate 50 and the substrate guide ring 920 and out of the through exhaust port 930. Preferably, the vertical distance between the top surface of the substrate 50 and the inlet 942 is 10 cm or less, more preferably 5 cm or less, and most preferably 2.5 cm or less.

In this embodiment, the heater 916, which is preferably a mica heater, is disposed circumferentially about the upper surface of the reactor upper portion 952. Preferably, another circumferentially configured heater 918 is located above the reactor chamber 950 and below the exhaust tube 932 at the top of the reactor middle portion 956. Preferably, O-rings 944, 948 are positioned between reactor top 928 and reactor middle portion 956.

Reactor chamber 950 incorporates substrate 50 and support mechanisms and provides a structure on substrate 50 that aids in the desired gas flow characteristics. Reactor chamber 950 includes a chamber bottom 962, a chamber top 964, and a chamber sidewall 966. In general, the chamber preferably provides an increase in gas flow rate with an increase near the center 1508 of the reactor chamber 950. Preservation of the angular momentum in combination with the inherent decrease in radial flow position as it progresses toward the center 1508 provides a first factor of speed increase with the decrease in distance from the center 1508. Preferably, the downward slope of the chamber top 964 towards the center 1508 provides a second factor of gas velocity increase as it moves toward the center 1508. In FIG. 9, a linear decrease in chamber height decreasing from the center 1508 is shown. However, it should be understood that both chamber bottom 962 and chamber top 964 can take a wide variety of shapes. In addition, a wide range of hydraulic relationships, both linear and non-linear, can be incorporated into a function of reactor chamber 950 height relative to radial position (distance from center 1508). In this embodiment, the chamber top 964 is inclined 14 ° (0.244 radians) with respect to the horizontal.

In this embodiment, the exhaust port 930 is substantially centered with respect to the reactor chamber 950 and is a vertical or substantially vertical hollow region above the center 1508 of the reactor chamber 950. Preferably, exhaust port 930 is connected to a horizontal exhaust tube 932, which ends at exhaust tube flange 934.

FIG. 10 is a cross-sectional side view of the vaporizer 100 and reactor 900 of FIG. 9 showing reactor housing 1014. FIG. 10 includes some heterogeneous components not described in connection with FIG. 9. These parts have been described above in connection with FIGS. 2 to 6, which are not shown in FIG. 9.

As shown in FIG. 9, the vaporizer 100 is connected to the reactor 900. The electrical lead wire 1002 is connected to one of the heaters for the vaporizer 100. Reactor housing 1014 surrounds reactor 900. The hinge arm 1004 is connected to the left side (in the figure of FIG. 10) of the reactor housing 1014. Preferably, hinge arm 1004 allows reactor housing 1014 to pivot to a location that does not shield reactor 900. The housing handle 1006 is shown connected to the right side (in the figure of FIG. 10) of the reactor housing 1014. Preferably, housing handle 1006 is used to move or pivot reactor housing 1014 to a desired position. In this embodiment, the tube plate 1010 is located on a spirally wound aluminum tube 1016, which is located on a heater 916. Preferably, tube 1016 is connected to gas valve 1008. Preferably, the outlet of the gas valve 1008 is connected to the top (in the figure of FIG. 10) of the carrier gas tube 1012 of the vaporizer 100.

FIG. 11 is a side cross-sectional view of the vaporizer 100 and reactor 900 of FIG. 9 showing a main exhaust connection 1106. FIG. 10 includes some heterogeneous components not described in connection with FIG. 9. These components previously described with respect to FIGS. 2-6 and 9 and 10 are not described in this section. Liquid conduit 1102 directs fluid over vaporizer 100. The electrical lead wire 1104 is connected to a heater (not shown) on the vaporizer 100.

In this embodiment, the exhaust port 930 is located above the center of the vaporization chamber 950. Preferably, exhaust port 930 is connected to exhaust tube 932, which is connected to main exhaust connection 1106. In this embodiment, the protective ring linkage 1108 is located near the left and bottom of the reactor 900 and operates to raise and lower the substrate protective ring 920 (FIG. 9). Preferably, the protective ring linkage 1108 raises the protective ring 920 while the substrate 50 is inserted into and removed from the reactor chamber 950. Preferably, once the substrate 50 is in place in the reactor chamber 950, the protective ring linkage device 1108 operates to lower the protective ring 920 to secure and protect the substrate 50. . Robotic arm access port 1110 is located on the left side (in the diagram of FIG. 11) and near the bottom of reactor 900. Preferably, curved shutter 1112 is located just to the right of access port 1110.

12 is a perspective view of a portion of reactor 900 showing multiple channels 968 exiting and guiding conduit 940. In this embodiment, 18 channels 968 are connected from conduit 940 into reactor chamber 960. However, fewer or more than 18 channels 968 may be used. However, where many channels 968 are used, the channels 968 are preferably evenly spaced about the circumference of the reactor chamber 950 along the conduit 940. 13 is an enlarged isometric view of a portion of conduit 940 and two channels 968 guiding through this portion. Preferably, the inlet 942 is located at the end of the chamber 950 of each channel 968. It can be seen that the angle between the axis of the channel 968 and the axis of the conduit 940 is an acute angle. Preferably, the axis between the channels 968 is substantially tangential to the direction of the axis of the conduit 940. 14 is a front sectional view of a portion of conduit 940 connected to tube 938 and channel 968. In this embodiment, six tubes 938 are provided, which are preferably equally spaced about the circumference of the reactor chamber 950. In alternative embodiments, more or less than six tubes 938 may be used. Moreover, in alternative embodiments, the tubes 938 may be non-uniformly distributed about the circumference of the chamber 950.

FIG. 15 is an enlarged side cross-sectional view of a portion of reactor chamber 950 shown in FIG. 9. Most of the device components shown in FIG. 15 have been described with reference to FIGS. 2-6 and 9-11, and thus description thereof is not provided here. In this embodiment, the substrate 50 is located above the susceptor. A gas flow boundary layer 1512 is over the substrate 50. The thickness of the boundary layer 1512 can be adjusted by controlling the velocity of the gas 954 as a function of the radial position 1520.

Now, the optimum gas heating operation will be described with reference to FIGS. 9 to 11. In this embodiment, the gas heating device is operated to use the availability of heat from reactor 900 to bring the carrier gas to the desired temperature after exiting reactor chamber 950. In this embodiment, after gas 954 exits reactor chamber 950, the gas is preferably compressed between tube plate 1010 and heater 916 (or other heater) 1016 ( 10). At this point, this gas is largely a carrier gas because most of the reactants have been removed from it. After processing through the tube 1016, the carrier gas is preferably directed to the valve 1008. Preferably, valve 1008 controls the delivery of carrier gas towards carrier gas conduit 1012 of vaporizer 100. Preferably, the carrier gas is at a temperature of about 200 ° C. In such a method, it may be advantageous to utilize the heat that is otherwise dissipated to generate "free" heating for the carrier gas oriented in the conduit 1012.

Operation of the embodiment of the CVD reactor described herein is described with reference to FIGS. A description of the features of reactor 10 of FIGS. 2-6 and reactor 900 of FIGS. 9-15 is provided. Thereafter, operation of the embodiment of FIGS. 9-15 is provided.

Reactor 900 of the embodiment of FIG. 9 is considerably shorter than reactor 10 of FIGS. One effect of this height reduction on the reactor 900 is to introduce the precursor gas 954 at a vertical height where the gas inlet system 922 of the reactor 900 is very close to the height of the top surface of the substrate 50. To do it. Preferably, this higher vertical proximity between the introduction of the gas and the substrate 50 increases the gas velocity in the vortex generated in each chamber.

Rotor 900 provides a modified system for introducing more gas into chamber 950 than is used in reactor 10. The reactor 10 of FIG. 5 uses a plurality of tubes to create a helical flow by injecting gas directly into the interior of the reactor 10. Reactor 900 (FIG. 9) includes a gas inlet system 922 for introducing gas into chamber 950. Preferably, the gas inlet system 922 includes a plurality of tubes 938 that orient the gas into the circumferential conduit 940 operating in the form of a gas manifold for the precursor gas 954. Precursor gas 954 circulates through conduit 940 and is introduced into reactor chamber 950 through a number of channels 968 leading to inlet 942, which is guided to inlet 942. The inlet 942 is guided into the reactor chamber 950. Preferably, the structure of the gas inlet system 922 provides improved gas flow uniformity around the inside of the reactor chamber 950 and good control of the orientation of the precursor gas 954 upon introduction into the reactor chamber 950. to provide.

Reactor 900 induces a height that changes the radial position. Although the height inside the reactor 10 of FIGS. 1-6 is basically constant, the height of the reactor chamber 950 (FIGS. 9-11 and 15) is radial from the chamber center 1508 of the reactor chamber 950. It is preferably a function of distance 1520. In the embodiment of FIG. 9, the change in chamber height is provided only by the inclined inner top surface of reactor chamber 950 because the bottom surface of reactor chamber 950 is substantially flat. However, in a variant embodiment, the bottom inner surface of reactor chamber 950 is formed to reduce the chamber height by reducing the distance from chamber center 508. In a variant embodiment, the bottom and top surfaces can be designed to be symmetric about a horizontal centerline separating these two parts. In another variant embodiment, the upper and lower portions have different chamber-height-change shapes.

The flow of gas in reactor chamber 950 is contemplated. The flow of precursor gas 954 from tube 938 through inlet 942 has been described above, and thus description thereof is omitted here. Similarly, the flow of precursor gas 954 depleted in the final direction through the tube 1010 (FIG. 10) into the vaporizer carrier gas 1012 has been described and thus also omitted herein. This section describes the ambient conditions and the flow conditions of the precursor gas 954 in the reactor chamber 950 between the discharge from the inlet 942 and the exhaust port 930.

Referring to FIG. 15, precursor gas 954 enters reactor chamber 950 at inlet 942, one of the inlets being shown on both sides of reactor chamber 950. The preferred embodiment of reactor chamber 950 has eighteen inlets 942. In the embodiment of FIG. 15, the gas 954 on the left side of the chamber 950 moves perpendicular to the plane of FIG. 15 and out of reference numeral 1502 of the ground. Similarly, on the right side, gas 954 moves perpendicular to the plane of FIG. 15 and into ground reference 1504. Upon exiting from the inlet 942, the precursor gas 954 preferably moves at a linear velocity of about 4 meters / second.

In this embodiment, the pressure and temperature conditions in reactor chamber 950 are tightly controlled due to the sensitivity of the various precursor reactants. In particular, the temperature should be high enough to prevent liquefaction and low enough to avoid premature degradation. Since many reactants may be included in precursor gas 954, atmospheric conditions should be selected to prevent liquefaction and premature decomposition of all these reactants. Preferably, precursor gas 954 is maintained at about 200 ° C. Preferably, the static pressure in chamber 954 is about 133.3 N / m 2 (Newtons per square meter) (1 Torr). Preferably, this low pressure environment can prevent the precursor gas from liquefying even at temperatures lower than those used in many existing MOCVD (metal organic chemical vapor deposition) reactor environments. Preferably, chamber sidewall 966 of reactor chamber 950 is maintained at about 190 ° C. In this embodiment, the substrate 50 is maintained at a temperature between 320 ° C. and 360 ° C., more preferably about 340 ° C. Preferably, the relatively low temperature of the substrate 50 prevents decomposition and particulate matter precipitation from the precursor 954 experienced in some existing reactors using higher substrate temperatures.

Preferably, the stationary state of the heated chuck 46 simplifies the design of the reactor 90 by eliminating the need for a mechanism for the rotary chuck 46. Apart from this, in conventional systems, rotation of the chuck 46 tends to complicate the route of thermocouple cables or other radix leads used for substrate temperature measurements. However, the fixed state of the chuck 46 in the reactor 900 is preferred, which makes the substrate temperature measurement less cumbersome by preventing the instrument leads from being disturbed by the rotation of the chuck 46 and the substrate 50. The substrate holder including the chuck 46 and the susceptor 48 holds the substrate 50.

In this embodiment, while proceeding from the inlet 942 toward the chamber center 1508, the precursor gas is accelerated by several factors. The first factor is the preservation of the angular momentum for which the product of V · R needs to remain constant for chambers of constant height, where V is the velocity and R is the radial position of the flow where V is measured. In chambers with unaltered heights, similar to reactor 10, this method obtained provides a constant boundary layer thickness of flow on substrate 50. This method obtained repeats the execution of the rotation of the substrate under the fixed showerhead, which practice is present in prior art showerhead-based gas distribution systems. However, in a helical gas system similar to that shown in FIGS. 2-6, the concentration of reactant of the precursor gas decreases progressively more as the movement increases through the interior of the reactor 10. Thus, the reactant concentration is lower near the center of reactor 10 than around. The combination of bottom reactants is moved near the center of the reactor 10 and the substantially uniform boundary layer flow thickness on the substrate 50 results in a lower film growth rate near the center of the substrate 50 in the reactor 10. do. In particular, for some processes performed in constant height reactors, the film growth rate at the center of the substrate 50 is only 20% of that achieved at the edge of the substrate 50. The growth rate achieved in the substrate 50 is about 10 ms / min.

Thus, a device is pursued to compensate for the reduction of reactants caused by moving towards the center of the reactor. This aids this practice by controlling the flow specification of the precursor gas 954, including the velocity of the gas flow on the substrate 50, in particular the velocity and boundary layer thickness 1512. One advantageous method involves changing the reactor chamber height as a function of radial position within reactor chamber 950, adding additional factors of speed increase as the distance from reactor center 1508 decreases. Preferably, higher flow rates reduce the thickness of the boundary layer 1512 of the flow on the substrate 50 and then increase the diffusion of reactants through the boundary layer 1512 to the substrate 50. Preferably, the increased rate of diffusion of the reactant compensates for the decrease in reactant concentration, resulting in a substantially uniform rate of film growth on the surface of the substrate 50. Since reactant reduction is increased with decreasing radial distance 1520, compensating for this practice may be accomplished by appropriately increasing the flow rate of gas 954 with decreasing radial distance 1520.

In general, reducing the height 1524 of the reactor chamber 950 as a function of the radial position 1520 causes the flow rate 1516 of the gas 954 to increase in height (all other factors affecting the flow rate 1516). In addition to the factor) increases inversely proportional to the decrease. The height 1524 will be varied with respect to the radial position Rx 1520 using linear and nonlinear functions, including exponential functions. In the embodiment of FIGS. 9-11 and 15, the chamber height 1524 varies linearly with the radial position 1520. However, those skilled in the art will appreciate that designs may be used that implement other mathematical relationships between chamber height and radial position.

Referring to FIG. 15, the velocity of precursor gas 954 at any arbitrary radial position Rx can be provided by the following equation.

Equation 1 Vx = V ₀ (Hi / Hx) Ri / Rx

Where Vx 1516 is the gas velocity, V ₀ 1512 is the starting gas velocity, Hi 1506 is the height of reactor chamber 950 where gas 954 is introduced into reactor chamber 950, and Hx 1524 is the height of reactor chamber 950 at radial position Rx 1510, Ri 1510 is the radius of reactor chamber 950, and Rx 1520 is the gas velocity Vx 1516 as indicated. The radial position to be measured. The relationship between the chamber height 1524 and the radial position 1520 changes the shape of the chamber bottom 962 and / or chamber top 964, based on the reactant reduction issued by the precursor gas 954. It can be adjusted by influencing the required rate of speed increase. Parameters related to determining the desired shape of reactor chamber 950 may be determined by experimentation and / or analysis. These variables include the proportion of reactant concentration as a function of the radial position 1520, the thickness of the boundary layer 1512d, the change in temperature and / or pressure along the radial position 1520, and over the substrate 50. Include, but are not limited to, the rate of membrane growth as a function of location.

Accordingly, the velocity of precursor gas 954 is accelerated according to Equation 1 when precursor gas 954 proceeds toward chamber center 1508. Preferably, the thickness of the boundary layer 1512 is reduced by reducing the size of Hx / Hi, thereby increasing the diffusion rate on the substrate 50 with Hi / Hx. Preferably, the rate of increase of diffusion rate from precursor gas 954 to substrate 59 as a function of decreasing Rx 1520 is substantially the same as the rate of decrease of reactant concentration over the same Rx 1520 range, This can achieve the desired compensation of the reactant concentration change with radial position. Preferably, by achieving this desired compensation, the rate of film growth is made substantially uniform over the surface of the substrate 50. Experiments using the attachment process in reactor chamber 950 indicate that the film growth rate at the center of the substrate 50 is 97% of that achieved at the edge of the substrate 500, ie, when using a constant height reactor. A large improvement of the 20% rate is achieved In addition, the growth rate achieved at the center of the substrate 50 is about 100 ms / min, which represents a 10-fold increase over the growth rate using a constant height reactor chamber.

In summary, a feature of the present invention is that the reactor volume utilizing the precursor gas as gas moves from the inlet 942 to the exhaust port 930 can be reduced by the present invention. That is, when the gas moves in the direction from the inlet 942 to the exhaust port 930, the reactor volume per unit distance along this direction is reduced. That is, for each cm of distance along the direction R, the volume included can be smaller in cm as the gas moves from the inlet 942 to the outlet port 930. In a preferred embodiment of the invention, the direction R is substantially radially inward. However, the present invention contemplates that the direction R may be substantially radially inward or in all other directions. Importantly, when the gas is removed from the chamber by adhesion, the volume used for the gas is reduced, so that the deposition rate per unit area of the substrate remains essentially the same.

Preferably, after reaching chamber region 1508 or a region substantially close thereto, precursor gas 954 proceeds through exhaust port 930 and along exhaust tube 932.

What has been considered presently as a preferred embodiment of the present invention has been described. It is to be understood that the invention can be embodied in other specific forms without departing from its scope or basic characteristics. For example, each feature of the invention described above may be combined with one or more of the features of the other invention. That is, although not all possible combinations of features of the invention have been disclosed in particular, many other combinations of features can be made unless the description is unreasonable. Thus, this embodiment is considered as shown. The scope of the invention is set forth in the appended claims.

Claims (39)

In chemical vapor deposition method, Providing a reactor chamber 950 comprising substrate holders 46 and 48 defining a substrate plane, Precursor gas is passed through the chamber in a circular motion in a direction R from the gas inlet 942 to the exhaust port 930 and about an axis 1508 substantially perpendicular to the substrate plane. Reducing the reactor volume per unit distance used for the precursor gas when the precursor gas moves in the direction; Activating the vapor to deposit a thin film on the surface of the substrate; Chemical vapor deposition. The method of claim 1, The moving step comprises providing a helical motion Chemical vapor deposition. The method of claim 1, The moving step includes increasing the velocity of the precursor gas as the precursor gas approaches the center of the reactor chamber. Chemical vapor deposition. The method of claim 1, Wherein said moving step comprises controlling the flow characteristics of said moved precursor gas to compensate for the reduction of reactants in said moved precursor gas. Chemical vapor deposition. The method of claim 1, The step of moving comprises controlling the flow specification of the moved precursor gas to make the film thickness across the substrate surface substantially the same. Chemical vapor deposition. The method of claim 1, Reducing the boundary layer thickness of the gas precursor flow on the substrate surface as the moving step approaches the center of the reactor chamber. Chemical vapor deposition. The method of claim 1, Increasing the diffusion rate of reactant from the precursor gas to the substrate surface as the moving step approaches the center of the reactor chamber. Chemical vapor deposition. The method of claim 1, The reactor chamber providing step includes providing a substantially circular reactor chamber, the direction being substantially radially inward. Chemical vapor deposition. The method of claim 1, Reducing the height of the reactor chamber as the reducing step approaches the center of the reactor chamber. Chemical vapor deposition. The method of claim 1, Further comprising substantially securing the substrate. Chemical vapor deposition. The method of claim 1, Maintaining the temperature of the reactor chamber below the decomposition temperature of the precursor gas; Chemical vapor deposition. The method of claim 11, The holding step includes maintaining a temperature of the sidewall of the reactor chamber at substantially 200 ° C. Chemical vapor deposition. The method of claim 11, The maintaining step includes maintaining the temperature of the precursor gas at substantially 200 ° C. Chemical vapor deposition. The method of claim 1, Maintaining the pressure in the reactor chamber to 10 Torr (1333 Newtons per square meter) or less. Chemical vapor deposition. The method of claim 1, Maintaining the pressure in the reactor chamber substantially at 1 Torr (1333 Newtons per square meter). Chemical vapor deposition. The method of claim 1, Maintaining the temperature of the substrate between 320 ° C. and 360 ° C. Chemical vapor deposition. The method of claim 1, Maintaining the temperature of the substrate at substantially 340 ° C. Chemical vapor deposition. The method of claim 1, The moving step causes the precursor gas to enter the reactor chamber 10 cm or less above the height of the substrate plane. Chemical vapor deposition. The method of claim 1, The step of causing the precursor gas to enter the reactor chamber 5 cm or less above the height of the substrate plane. Chemical vapor deposition. The method of claim 1, The moving step causes the precursor gas to enter the reactor chamber 2.5 cm or less above the height of the substrate plane. Chemical vapor deposition. In a chemical vapor deposition (CVD) reactor 900, Reactor chamber 950, Substrate holders 46 and 48 located in the reactor chamber and defining a substrate plane; A gas inlet system 922 comprising a gas inlet 942, A gas outlet port 930, The reactor chamber is formed such that the reactor chamber per unit distance is reduced in the direction R from the gas inlet to the gas outlet port. Chemical vapor deposition reactor. The method of claim 21, The reactor chamber comprises a circular wall and the gas inlet system comprises a gas inlet oriented substantially tangentially to the circular wall. Chemical vapor deposition reactor. The method of claim 21, The reactor chamber is substantially circular and the direction is radially inward Chemical vapor deposition reactor. The method of claim 21, The reactor includes an upper wall and is increased as the height of the reactor chamber upper wall above the substrate holder increases the distance from the center of the chamber. Chemical vapor deposition reactor. The method of claim 24, The height of the chamber upper wall above the substrate holder varies substantially linearly by a distance from the center of the chamber Chemical vapor deposition reactor. The method of claim 21, The reactor comprises an upper wall, wherein the height of the reactor chamber upper wall above the substrate is a function of the rate of reactant reduction in the chamber. Chemical vapor deposition reactor. The method of claim 21, The reactor includes an upper wall and the height of the reactor chamber upper wall above the substrate is varied in radial position to compensate for the rate of reactant reduction during gas flow through the chamber. Chemical vapor deposition reactor. The method of claim 21, The reactor comprises an upper wall, the shape of the chamber being designed to provide a substantially uniform film growth rate on a substrate located on the substrate holder Chemical vapor deposition reactor. The method of claim 21, Substantially secured in the reactor such that the substrate holder is substantially secured. Chemical vapor deposition reactor. The method of claim 21, The substrate holder includes a heater Chemical vapor deposition reactor. The method of claim 21, The gas inlet system comprising a plurality of tubes arranged to direct gas into the conduit Chemical vapor deposition reactor. The method of claim 21, The gas inlet system comprising a conduit arranged circumferentially about the reactor chamber Chemical vapor deposition reactor. The method of claim 21, The gas inlet system includes a plurality of channels through the reactor chamber Chemical vapor deposition reactor. The method of claim 33, wherein The channel oriented substantially tangentially to the sidewall of the reactor chamber Chemical vapor deposition reactor. The method of claim 21, The inlet is at the periphery of the reactor chamber Chemical vapor deposition reactor. The method of claim 21, The gas inlet system, the reactor chamber and the gas exhaust port cooperate to provide a spiral gas flow over the substrate holder from the interior periphery of the chamber to the gas exhaust port. Chemical vapor deposition reactor. The method of claim 21, The exhaust port is substantially centrally located within the reactor Chemical vapor deposition reactor. The method of claim 21, Wherein the chamber comprises an upper wall, wherein at the periphery of the chamber the upper wall is 10 cm or less above the substrate plane and near the exhaust port, and the top wall is 5 cm above the substrate plane. Or higher Chemical vapor deposition reactor. The method of claim 21, Wherein the chamber comprises an upper wall, at the periphery of the chamber the upper wall is 5 cm or less above the substrate plane and near the exhaust port, and the top wall is 2.5 cm above the substrate plane. Or higher Chemical vapor deposition reactor.