A vapor deposition apparatus

Abstract

The present invention relates generally to the field of semiconductor manufacturing technology and provides a vapor deposition apparatus comprising a chamber in which a substrate is arranged, a first gas inlet, wherein a main process gas is configured to enter the chamber from the first gas inlet and to flow parallel to the substrate from a first side of the substrate to a second side, a second gas inlet, wherein a secondary gas is configured to enter the chamber from the second gas inlet, a first gas outlet, wherein the first gas outlet is configured to remove the main process gas, and a second gas outlet, wherein the second gas outlet is configured to remove the secondary gas. The present invention provides a forced laminar flow control by mass flow control of the gas outlets, so that when additional gas flows are injected into the horizontal laminar flow due to interface layer control and other process requirements, their adverse disturbance of the laminar flow can be suppressed.

Description

Technical Field

[0001] This invention generally relates to the field of semiconductor manufacturing technology. Specifically, this invention relates to a vapor deposition apparatus for improving the quality of thin films deposited on a substrate. Background Technology

[0002] Vapor phase chemical processes, particularly chemical vapor deposition (CVD), are prevalent in the semiconductor and broader semiconductor industries. CVD processes typically require high temperatures to activate the reactive gases. These reaction chambers are categorized as hot-wall or cold-wall chambers based on their temperature relative to the substrate being processed (e.g., silicon wafers, silicon carbide, sapphire). For certain processes (e.g., vapor-phase single crystal growth), the substrate must be confined within a laminar flow environment to grow suitable thin or thick films.

[0003] Figure 8 A schematic diagram of a typical pneumatic vacuum pressure control loop in the prior art is shown. In this loop, a vacuum pump located downstream provides negative pressure. A back pressure control valve is located between the reaction vessel or chamber, and a PT pressure sensor is installed at the outlet of the reaction vessel. The PT pressure sensor feeds back the measured pressure to a pressure controller. The pressure controller outputs a valve opening signal to the pneumatic controller according to a PID control law or other control law. The pneumatic controller then outputs pneumatic pressure to the back pressure control valve based on the valve controller, ultimately achieving pressure control at the PT pressure sensor. It is evident that the control of inputs, outputs, and control laws in the prior art is based on pressure.

[0004] However, in existing technologies, when additional gas flow is injected into horizontal laminar flow due to interface layer control and other process requirements, fluid control in the system becomes extremely important. The additional gas may increase the gas flow rate and raise the Reynolds coefficient; furthermore, the kinetic energy of the injected gas may cause undesirable disturbances to the laminar flow. Therefore, a control method and device are needed to better control laminar flow. Summary of the Invention

[0005] To at least partially solve the above-mentioned problems in the prior art, the present invention proposes a...

[0006] A cavity, in which a substrate is arranged;

[0007] A first air inlet is arranged on a first side of the cavity, wherein the main process gas is configured to enter the cavity from the first air inlet and flow parallel to the substrate from the first side of the substrate to the second side.

[0008] A second air inlet is arranged on the first side of the cavity and above the first air inlet, wherein auxiliary gas is configured to enter the cavity from the second air inlet;

[0009] A first exhaust port is disposed on the second side of the cavity, wherein the first exhaust port is configured to exhaust the main process gas; and

[0010] A second exhaust port is disposed on the second side of the cavity, wherein the second exhaust port is configured to discharge the auxiliary gas.

[0011] The second exhaust port can improve the laminar flow in the cavity, and the second air inlet can control the height of the interface layer.

[0012] In one embodiment of the present invention, the auxiliary gas includes a suppressing gas, which includes an inert gas, an inactive gas, a carrier gas, and an etching gas.

[0013] In one embodiment of the present invention, the exhaust rate of the second exhaust port is the same as or within the same range as the intake rate of the second intake port; or

[0014] The exhaust rate of the second exhaust port is proportional to the intake rate of the second intake port, and the exhaust rate of the first exhaust port is proportional to the intake rate of the first intake port.

[0015] In one embodiment of the present invention, it is specified that it further includes:

[0016] An air pump is connected to the first exhaust port and the second exhaust port.

[0017] In one embodiment of the present invention, the ratio of the opening area of ​​the first exhaust port to the opening area of ​​the second exhaust port is the same as the ratio of the intake volume of the process gas to the intake volume of the auxiliary gas.

[0018] Mass flow control (standard liters per minute (SLM) or standard cubic centimeters per minute (SCCM)) can be performed at the first and second air inlets. Therefore, only proportional control is required at the first and second exhaust ports.

[0019] In one embodiment of the present invention, the vapor deposition apparatus further includes:

[0020] A throttle valve is connected to the first exhaust port and the second exhaust port, wherein the throttle valve is configured to control the exhaust rate of the first exhaust port and the second exhaust port so that the exhaust rate of the first exhaust port is the same as the intake rate of the main process gas, the exhaust rate of the second exhaust port is the same as the injection rate of the auxiliary gas, and the pressure of the process chamber is maintained within a set pressure range.

[0021] In one embodiment of the present invention, the vapor deposition apparatus further includes:

[0022] A third air inlet is disposed at the upper part of the cavity, wherein a third gas is configured to enter the cavity from the third air inlet.

[0023] Among them, the third gas usually affects the uniformity or quality of film formation, and the auxiliary gas can isolate the third gas from the main process gas.

[0024] In one embodiment of the present invention, the third gas is configured to be discharged through the second exhaust port, the main process gas is configured to be discharged through the first exhaust port, and the auxiliary gas is configured to be discharged through either the first exhaust port or the second exhaust port.

[0025] In one embodiment of the present invention, at least one of the first exhaust port and the second exhaust port is subject to mass flow control so that the third gas and the auxiliary gas are discharged from the second exhaust port.

[0026] Among them, mass flow control refers to control based on a settable gas mass flow rate, that is, standard liters per minute or standard milliliters per minute, which is different from the existing control based on flow rate m / s or fixed pressure difference (pump). This allows the third gas and the auxiliary gas to be discharged from the second exhaust port without entering the first exhaust port, that is, to form forced laminar flow.

[0027] In one embodiment of the present invention, the mass flow control includes:

[0028] Flow rate is measured using ultrasound and then converted into mass flow rate using pressure and temperature for control purposes.

[0029] and / or

[0030] Quality control is achieved using a Coriolis mass flow meter, which measures based on the Coriolis force generated by the fluid flowing in a vibrating pipe, which is proportional to the mass flow rate.

[0031] In one embodiment of the present invention, the number of the first air inlets is m, and the number of the second air inlets is n, where m and n ≥ 2.

[0032] In one embodiment of the present invention, a plurality of first air inlets are arranged in parallel.

[0033] The multiple first air inlets arranged in parallel can be used to adjust the film thickness or doping.

[0034] In one embodiment of the present invention, the vapor deposition apparatus includes:

[0035] A baffle plate is disposed on the first exhaust port and the second exhaust port. The baffle plate is movable, wherein the opening ratio of the first exhaust port and the second exhaust port is adjusted by moving the baffle plate to adapt to the ratio of the first air inlet to the second air inlet.

[0036] In one embodiment of the present invention, the auxiliary gas includes a process gas, wherein the mass flow rate difference resulting from an increase or decrease in the molar amount produced by the reaction of the process gas is compensated.

[0037] When the auxiliary gas is the process gas, the molar amounts of gaseous substances on both sides of the reaction may change. Therefore, it is necessary to compensate for the mass flow rate difference caused by the increase or decrease in the molar amount produced by the reaction. This can be expressed as the following formula:

[0038] Precursor gas a(g) + b(g)

[0039] →Sediment(s) + Byproduct(g)

[0040] Mol(Δ)=Mol(byproduct)-mol(a)-mol(b)

[0041] In one embodiment of the present invention, n air inlets 1 to n are provided, and n exhaust outlets exhaust1 to n are provided. The air intake volume of the air inlets is expressed as ∑inj 1 to n, wherein mass flow control is performed on the exhaust outlets exhaust1 to (n-1).

[0042] The flow rate of exhaust port exhaust n can be obtained by ∑inj 1~n-∑exhaust1~(n-1), so only pressure or other control or monitoring is required for exhaust port exhaust n.

[0043] In one embodiment of the present invention, the vapor deposition apparatus further includes:

[0044] A third exhaust port is disposed on the second side of the cavity, wherein the third exhaust port is configured to discharge the third gas.

[0045] In this invention, the gases entering the cavity include process gas inj 1 entering from the first inlet, auxiliary gas inj 2 entering from the second inlet, and a third gas inj 3 entering from the third inlet. The third gas inj 3 can be an etching or cleaning gas. Etching or cleaning gases typically readily exchange mass with the substrate or process gas inj 1, therefore they need to be isolated by the auxiliary gas inj 2. Process gas inj 1, auxiliary gas inj 2, and third gas inj 3 can be discharged through the first exhaust port exhaustt1, the second exhaust port exhaustt2, and the third exhaust port exhaustt3, respectively; or, as in the aforementioned embodiment, auxiliary gas inj 2 and third gas inj 3 can be discharged through the second exhaust port exhaustt2.

[0046] In addition, etching gas can also be introduced through the first air inlet, and various combinations of gases can be made for the first to third air inlets.

[0047] In one embodiment of the present invention, the third gas is configured to be discharged through the second exhaust port, wherein the exhaust volume of the first exhaust port is greater than the intake volume of the process gas and less than the sum of the intake volumes of the process gas and the auxiliary gas, and the exhaust volume of the second exhaust port is greater than the exhaust volume of the third gas and less than the sum of the intake volumes of the third gas and the auxiliary gas.

[0048] In one embodiment of the invention, the second exhaust port is configured to provide upward kinetic energy to the third gas.

[0049] Since the third gas enters from the top of the cavity downwards, it will have a vertically downward velocity component V. down The downward distance of the third gas can be expressed as follows:

[0050]

[0051] Where L chamber V represents the horizontal distance the third gas travels within the cavity. level This represents the horizontal velocity component of the third gas. When V down If the value is too high, the third gas may blow onto the substrate, affecting the substrate's processing; while when V... down If the size is too small, and the opening above the cavity is also too small (for example, when the heater occupies 60% of the area at the top of the cavity, the opening may occupy 30% of the area at the top of the cavity, considering the cavity structure), the intake volume of the third gas may be insufficient. Therefore, an upward kinetic energy (negative pressure) can be provided by the second exhaust port located at the top so that the third gas entering near the first side of the cavity will not affect the film formation on the rear half of the substrate.

[0052] Specifically, the upward kinetic energy does not imply that the third gas has a large upward linear velocity, or that the gas outlet has an upward angle. Hydrodynamic model analysis shows that when the outlet is horizontal but much higher than the substrate, or has a portion closer to the upper surface of the cavity, the high-level exhaust port, or the high portion of the exhaust port, is sufficient to provide upward energy.

[0053] Figure 7A The diagram shows a velocity streamline within a cavity where negative pressure is not provided through the exhaust port, as shown below. Figure 7A As shown, the third gas can easily reach the substrate and exit from the first exhaust port. Figure 7B The diagram shows a velocity streamline within a cavity that provides negative pressure through an exhaust port, as shown in one embodiment of the present invention. Figure 7B As shown, the upward kinetic energy provided by the horizontal negative pressure of a second exhaust port can flatten the third gas, preventing it from reaching the substrate and allowing it to exit from the second exhaust port. In fact, an outlet located at a higher position could also provide upward kinetic energy if it pointed downwards.

[0054] In one embodiment of the present invention, the third gas is injected in sections to adjust the thickness of the boundary layer of the process gas and control the deposition rate at each point on the substrate, thereby achieving control over the film thickness at each point on the substrate and improving the uniformity of film formation on the substrate.

[0055] In one embodiment of the present invention, it is specified that the exhaust ratio of the first exhaust port and the second exhaust port is adjusted (that is, adjusted) Figure 2B The outputs A (x%) and B (y%) shown are used to control the boundary layer height of the process gas above the substrate near the second side of the cavity.

[0056] In one embodiment of the present invention, the vapor deposition apparatus further includes:

[0057] A fourth air inlet is arranged on the first side of the cavity, and the fourth air inlet is arranged below the first air inlet.

[0058] Specifically, the gas entering the cavity from the fourth air inlet can suppress the purge gas below from entering above the substrate, or it can suppress the gas above the substrate from entering the lower part of the cavity.

[0059] This invention provides a horizontal multidimensional injection cavity that achieves forced laminar flow control by controlling the mass flow rate of the exhaust port. The core of this invention lies in: using the area ratio of the outlets to distribute the mass flow rate when the injection is controlled by mass flow rate; using opening valves to control the opening of multiple outlets, thereby controlling the mass flow rate; and measuring the mass flow rate at multiple outlets in real time to further control the valve opening in a closed-loop manner, thus achieving mass flow rate control of multiple outlets and ultimately achieving forced laminar flow control.

[0060] The present invention has at least the following beneficial effects: The present invention provides a vapor deposition apparatus that performs forced laminar flow control by controlling the mass flow rate of the exhaust port. Therefore, when additional gas flow is injected into the horizontal laminar flow due to interface layer control and other process requirements, it can suppress the adverse disturbance to the laminar flow. Attached Figure Description

[0061] To further illustrate the advantages and other features of the various embodiments of the present invention, a more specific description of the embodiments of the present invention will be presented with reference to the accompanying drawings. It is understood that these drawings depict only typical embodiments of the invention and are therefore not intended to limit its scope. In the drawings, identical or corresponding parts will be indicated by the same or similar reference numerals for clarity.

[0062] Figure 1 A schematic diagram of a horizontal vapor deposition chamber in the prior art is shown.

[0063] Figure 2A A schematic diagram of a vapor deposition apparatus according to one embodiment of the present invention is shown.

[0064] Figure 2B A schematic diagram of a vapor deposition apparatus according to another embodiment of the present invention is shown.

[0065] Figure 2C A schematic diagram of a multi-channel fluid switch box is shown in one embodiment of the present invention.

[0066] Figure 3 A schematic diagram of a cavity is shown in one embodiment of the present invention.

[0067] Figure 4 A schematic cross-sectional view of a cavity is shown in one embodiment of the present invention.

[0068] Figure 5A A schematic diagram of the gas velocity distribution within the cavity is shown when using an existing top cover or dome.

[0069] Figure 5BA schematic diagram of the gas velocity distribution within a cavity is shown when a diffused top cover or dome is used in one embodiment of the present invention and diffused gas is injected into the cavity.

[0070] Figure 5C A schematic diagram of the gas flow lines inside the cavity is shown when using an existing top cover or dome.

[0071] Figure 5D A schematic diagram of the gas flow lines inside the cavity is shown when a diffused top cover or dome is used in one embodiment of the present invention and diffused gas is injected into the cavity.

[0072] Figure 6 A schematic diagram illustrating the effect of diffuse surface on chemical vapor deposition process in one embodiment of the present invention is shown.

[0073] Figure 7A The diagram shows the velocity streamlines within a cavity where negative pressure is not provided through the exhaust port.

[0074] Figure 7B The diagram shows a velocity streamline within a cavity that provides negative pressure through an exhaust port, according to one embodiment of the present invention.

[0075] Figure 8 A schematic diagram of a typical pneumatic vacuum pressure control loop in the prior art is shown.

[0076] Figure 9A -B shows a schematic diagram of a mass flow measurement principle based on ultrasound.

[0077] Figure 10 A schematic diagram of a mass flow measurement principle based on the Doppler effect is shown.

[0078] Figure 11 A schematic diagram illustrating the principle of interface layer theory is shown. Detailed Implementation

[0079] It should be noted that the components in the various figures may be shown exaggeratedly for illustrative purposes and are not necessarily to scale. In each figure, the same reference numerals are used for components that are identical or have the same function.

[0080] In this invention, unless otherwise specified, "arranged on," "arranged above," and "arranged on" do not exclude the possibility of an intermediate element between them. Furthermore, "arranged on or above" merely indicates the relative positional relationship between two components, and in certain cases, such as when the product orientation is reversed, it can also be converted to "arranged below or under," and vice versa.

[0081] In this invention, the various embodiments are merely intended to illustrate the solutions of the invention and should not be construed as limiting.

[0082] In this invention, unless otherwise specified, the quantifiers “a” and “one” do not exclude scenarios involving multiple elements.

[0083] It should also be noted that, in the embodiments of the present invention, only a portion of the components or parts may be shown for clarity and simplicity. However, those skilled in the art will understand that, under the teachings of the present invention, necessary components or parts can be added as needed for specific scenarios. Furthermore, unless otherwise stated, features in different embodiments of the present invention can be combined with each other. For example, a feature in the second embodiment can replace a corresponding or functionally identical or similar feature in the first embodiment, and the resulting embodiment will also fall within the scope of disclosure or description of this application.

[0084] It should also be noted that, within the scope of this invention, the terms "same," "equal," and "equal to" do not imply that the two values ​​are absolutely equal, but rather allow for a certain reasonable margin of error. In other words, the terms also encompass "substantially the same," "substantially equal," and "substantially equal to." Similarly, in this invention, the directional terms "perpendicular to," "parallel to," etc., also encompass the meanings of "substantially perpendicular to" and "substantially parallel to."

[0085] Furthermore, the numbering of the steps in the methods of the present invention does not limit the execution order of the method steps. Unless otherwise specified, the method steps may be executed in different orders.

[0086] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0087] Figure 1 A schematic diagram of a horizontal vapor deposition chamber in the prior art is shown. Figure 1 As shown, the cavity includes a deposition system 100, a process gas inlet 101, a cavity exhaust 102, a base 103, a substrate 104, an upper dome or upper pad 105, a lower pad 106, a process (e.g., epitaxial) film deposition 107, an upper pad film deposition 108, and a lower pad film deposition 109. The substrate 104 (e.g., a silicon, silicon carbide, or sapphire substrate) is located in the middle of the cavity. The process gas enters the cavity from the inlet 101 on one side, flows through the cavity and the upper surface of the substrate 104, and then exits from the exhaust 102 at the cavity's tail end on the other side. As shown by the arrows in the figure, when the process gas flows through the upper surface of the substrate 104, a portion flows towards the substrate.

[0088] Figure 9A -B illustrates a schematic diagram of an ultrasonic-based mass flow rate measurement principle. (See diagram below.) Figure 9AAs shown, in the mass flow exhaust control method, the flow velocity v is measured by ultrasound, and the volumetric flow rate L / min is obtained by integrating the flow velocity v over the pipe cross-section. The pressure sensor measures the pressure P, and the temperature sensor measures the temperature T. The pressure P and temperature T are converted into the standard volumetric flow rate SLM (one atmosphere at 25 degrees Celsius).

[0089] Specifically, the mass flow meter is usually located upstream of the cavity, such as... Figure 9B As shown, the formula for calculating the flow rate using a pair of ultrasonic flow meters (velocity meters) is as follows:

[0090]

[0091]

[0092]

[0093]

[0094] Where v represents fluid velocity, c represents speed of sound, t1 represents upstream transmission time, and t2 represents downstream transmission time.

[0095] The sound velocity and flow velocity can be calculated using the above formulas. Integrating the flow velocity over the cross-sectional area yields the volumetric flow rate of the fluid over that area. Using the ideal gas law PV = nRT, the corresponding mass flow rate (standard liters per minute or standard milliliters per minute) can be calculated. Therefore, pressure and temperature sensors are needed to measure the temperature and pressure at the control point. In other words, Mass Flow Exhaust Rate = Function(velocity, pressure, temperature). The mass flow exhaust rate can be calculated based on the flow velocity, pressure, and temperature. Therefore, for a given exhaust mass flow rate at the set point at the outlet, after calculating the flow velocity and volumetric flow rate based on the measured t1 and t2, it is converted to the standard mass flow rate according to the temperature and pressure.

[0096] In fact, for this invention, outlet mass flow control, volumetric flow control, and even velocity flow control can be normalized, and the most suitable measurement technology and algorithm can be selected for control depending on different fluid conditions.

[0097] Figure 10 A schematic diagram illustrating the principle of mass flow measurement based on the Doppler effect is shown. Figure 10As shown, assuming the velocity of the particles flowing in the liquid is V, the light illuminating the particles is a plane monochromatic wave with wave vector k, light frequency v0, and light speed c (generally, v is much smaller than c), according to the theory of relativity, the frequency of the light scattered by the particles relative to the light wave shifts due to the Doppler effect. The frequency v′ of the light scattered by the particles can be expressed as follows:

[0098]

[0099] Where θ represents the angle between the light wave vector and the particle vector.

[0100] The Doppler frequency shift Δv produced by the scattered light relative to the incident light can be expressed as follows:

[0101]

[0102] Where λ represents the wavelength of the scattered light.

[0103] The measurement principle of gas and fluid is the same as that of laser measurement. By replacing the beam used for measurement with ultrasound, and simply replacing the speed of light in the above formula with the speed of sound at the current temperature and pressure of the gas, the corresponding fluid velocity can be obtained through Δv, and then the corresponding volumetric flow rate can be determined.

[0104] In addition, a Coriolis mass flow meter, which can directly obtain the mass flow rate, can also be used as an option in this invention. Its principle and detailed measurement principle will not be elaborated further.

[0105] Figure 2A A schematic diagram of a vapor deposition apparatus 200 according to one embodiment of the present invention is shown. Figure 2A As shown, the device includes a cavity 300, a process gas A pipeline and inlet 201, a process gas A supply and control device 202, a cavity inlet gas B pipeline and inlet 210 for controlling the process gas boundary layer, a cavity inlet gas B supply and control device 211 for controlling the process gas boundary layer, a cavity upper diffuse gas C pipeline and inlet 220, a cavity upper diffuse gas C supply and control devices 221 and 222, a cavity exhaust lower exhaust port and pipeline 230, a cavity exhaust lower exhaust control device 231, a cavity exhaust upper gas exhaust port and pipeline 240, and a cavity exhaust upper gas exhaust control device 241.

[0106] The cavity 300 is either a hot-wall cavity or a cold-wall cavity, and the cavity 300 contains a base 103, a substrate 104, and gaskets 106, 150, and 151 (see...). Figure 4 ).

[0107] The main process gas A enters the cavity 300 from the cavity inlet side through inlet 201. The process gas A supply and control device 202 controls the flow rate of the process gas, for example, through a mass flow meter (MFC).

[0108] Gas B, used to control the boundary layer of the process gas, enters the cavity from above the inlet side through inlet 210. The supply and control device 211 for gas B above the inlet side controls gas B, for example, by controlling the flow rate of gas B via an MFC. Gas B is used to control the thickness and distribution of the boundary layer above the substrate for process gas A. By adjusting gas B, such as increasing its flow rate, process gas A is forced towards the substrate, reducing the vertical space of gas A, increasing its flow rate, and thinning the boundary layer. This allows more process gas reactants to diffuse through the boundary layer to the substrate surface, where they undergo chemical reactions to form a thin film. Simultaneously, increasing gas B makes it more difficult for process gas A to reach the upper dome or upper liner 150 and 151 via diffusion or thermal buoyancy, reducing unwanted additional film formation and particulate matter on the inner wall of the cavity.

[0109] The upper diffused gas C enters from the upper diffused gas C pipeline and inlet 220 above the cavity. The supply and control devices 221 and 222 for the upper diffused gas C can control the flow rate or velocity of the diffused gas C. The diffused gas covers the upper surface linings 150 and 151 of the inner wall of the cavity as much as possible. This firstly prevents the process gas A from reaching the upper dome or upper linings 150 and 151 through diffusion or thermal buoyancy, thus preventing additional film formation and particulate matter formation. Secondly, a certain amount of etching gas can be used to etch and clean the areas where films have already formed, ensuring the cleanliness of the upper dome or upper linings 150 and 151.

[0110] The cavity R side (located on the opposite side of L side) is provided with a lower exhaust port and a pipeline 230. The by-product gas and residual gas of process gas A after the chemical gas phase reaction are mainly discharged from the cavity through pipeline 230. In addition, part of the upper gas B used to control the boundary layer of process gas is also discharged from the cavity through pipeline 230.

[0111] The cavity R side (located on the opposite side of L side) is provided with an upper exhaust port and pipeline 240. The diffuse gas C in the upper part of the cavity is mainly discharged through 240. In addition, part of the upper gas B used to control the process gas boundary layer is also discharged from the cavity through 240.

[0112] Diffuse gas C enters the cavity through an upper dome or upper liner 151 containing diffused orifices. At least a portion of 151 is located directly above the substrate 104. The diffused orifices have a characteristic size of 0.1-2 mm, and their area accounts for 5%-50% of the area of ​​the dome 151. The diffused gas can be controlled in zones, as shown in... Figure 2A As shown, individual control is achieved through control devices 221 and 222, but more precise control of different zones can also be performed as needed.

[0113] Figure 2B A schematic diagram of a vapor deposition apparatus 400 according to another embodiment of the present invention is shown. Figure 2B As shown, the device includes a cavity 300, a process gas A pipeline and inlet 201, a process gas A supply and control device 202, a cavity inlet gas B pipeline and inlet 210 for controlling the process gas boundary layer, a cavity inlet gas B supply and control device 211 for controlling the process gas boundary layer, a cavity inlet gas B′ pipeline and inlet 210′ ​​for controlling the process gas boundary layer, a cavity B′ supply and control device 211′, a cavity upper diffused gas C pipeline and inlet 220, cavity upper diffused gas C supply and control devices 221, 222 and 223, a cavity exhaust port and pipeline 230, a cavity exhaust port and pipeline 240, a cavity exhaust side upper gas exhaust port and pipeline 240, a multiple flow switch box 270, pressure sensors 251 and 252, a temperature sensor 253, and a control unit 250.

[0114] exist Figure 2B The middle arrow indicates the gas flow path, and BL 1-5 represent the height of the boundary layer. The height of BL1-BL4 can be controlled by control devices 221-224.

[0115] Figure 2C A schematic diagram of a multi-channel fluid switch box 270 according to one embodiment of the present invention is shown. Figure 2C As shown, the multi-channel fluid switch box 270 may include: a proportional regulating valve 232 for the lower exhaust pipe 230 on the exhaust side of the cavity, a proportional regulating valve 242 for the upper exhaust pipe 240 on the exhaust side of the cavity, a mass flow meter 243 on the rear side of the exhaust end of the 240, and a pump 260 for evacuation.

[0116] The process control via PID control unit 250, where exhaust flow control and chamber pressure control are jointly implemented, may include the following scenarios: Byproduct gases and residual gases from the chemical vapor phase reaction of process gas A are primarily discharged from the chamber through the lower exhaust pipe 230 on the exhaust side; gases B and B′ used to create the process gas boundary layer are partially discharged through the lower exhaust pipe 230 and partially through pipe 240; diffuse gas C in the upper part of the chamber is primarily discharged through pipe 240; and flow data from the mass flow meter 243 at the rear end of exhaust pipe 240 is transmitted to the PID control unit 250. 50. According to the process setpoint, the PID control unit adjusts the proportional control valves 232 and 242 to control the relative mass flow rates at the outlets of pipelines 230 and 240. The cavity pressure sensor 251 collects the pressure of the process cavity 300 and transmits it to the PID control unit 250. According to the process pressure setpoint, the PID control unit 250 synchronously and proportionally adjusts the proportional control valves 232 and 242 so that the cavity pressure reaches the setpoint. The mass flow rate of the gas at the exhaust port corresponding to pipeline 240 is x%, and the mass flow rate of the gas at the exhaust port corresponding to pipeline 230 is y%, where x% + y% = 1.

[0117] Figure 3 A schematic diagram of a cavity 300 according to one embodiment of the present invention is shown. Figure 3 As shown, the left and right sides of cavity 300 are cavity L and cavity R sides, respectively. Process gas A inlets 201A, 201B, and 201C are arranged on cavity L side. Above cavity L side is gas B inlet 210A for controlling the process gas boundary layer. Gas inlets 210B and 210C are arranged at the front and rear of cavity L side to protect the front and rear walls of the cavity, preventing process gas A from diffusing to the front and rear walls. Similarly, a gas path can be provided to protect the bottom of the cavity to prevent process gas A from diffusing in. A diffuse gas C inlet 220A is provided at the top of the cavity, and 220B indicates the flow direction of diffuse gas C at the top of the cavity. A lower exhaust port 230 is provided on cavity R side, and an upper exhaust port 240 is provided on cavity R side. Although... Figure 3 The diagram shows diffuse gas C flowing through the front and rear sides of the cavity. Diffuse gas C is not shown flowing through the bottom of the cavity, but it can be added as needed.

[0118] Figure 4 A schematic cross-sectional view of a cavity 300 according to one embodiment of the present invention is shown. Figure 4As shown, the cavity 300 may include a process gas A pipeline and inlet 201, a gas B pipeline and inlet 210 above the cavity inlet side for controlling the process gas boundary layer, an opening 212 inside the cavity at the gas B location above the cavity inlet side for controlling the process gas boundary layer, a diffuse gas C pipeline inlet 220 at the top of the cavity, a lower exhaust port 230 on the cavity exhaust side, a gas exhaust port 240 above the cavity exhaust side, a base 103, a substrate 104, a process (e.g., epitaxial) film deposition 107, a lower liner 106, a lower liner film deposition 109, and an upper dome or upper liner 150 (an upper dome or upper liner 151 containing diffused small holes). Figure 4 The diagram also shows the trace Fp1 of process gas A, the trace Fp2 of gas B above the inlet side of the cavity used to control the process gas boundary layer, and the trace Fp3 of gas C diffused in the upper part of the cavity.

[0119] The substrate 104 can be a wafer or a substrate material of the same or different materials as the vapor-deposited thin film. The substrate 104 can be silicon, germanium, germanium-silicon, silicon carbide (SiC), sapphire, III-V group, II-VI group compound semiconductors, etc. Here, III-V materials are mainly aluminum (Al), gallium (Ga), and indium (In), while V-V materials are mainly nitrogen (N) and phosphorus (P). Of course, ternary or quaternary compound semiconductor substrate materials are also applicable. Widely used materials include GaN, GaAs, InP, AlGaN, AllnN, and AllNGaN.

[0120] The main process gas A enters the cavity through inlet 201 from the inlet side, flows through the cavity and the upper surface of the substrate 104, and a portion diffuses through the boundary layer above the substrate to the substrate, where it undergoes a gas-phase reaction to form a film on the substrate surface. The byproduct gas after the chemical vapor phase reaction and the residual gas of process gas A are discharged from the exhaust port 230 on the other side of the cavity. The substrate can be heated by an infrared lamp outside the quartz cavity, by a hot-wall cavity, or by induction heating.

[0121] The main process gas A depends on the process conditions and typically contains reactant gases, carrier gases, or etching gases. Reactant gases may contain one or more of the following: SiH4, DCS (SiH2Cl2), TCS (SiHCl3), SiCl4, B2H6, PH3, AsH3, C3H8, C2H4, N2, NH3, TMGa, TMAl, etc. Carrier gases are usually one or more of H2 and Ar. Etching gases may contain one or more of the following: HCl, Cl2, CF4, etc.

[0122] The gas B above the inlet side of the cavity used to control the process gas boundary layer can be a gas with a low diffusion coefficient or an inert gas, such as one or more of H2, He, Ne, Ar, Kr, Xe, and N2. It can also contain etching gases, such as one or more of HCl, Cl2, and CF4. For SiC thin film epitaxy, carbon-containing gases such as C3H8 can also be used.

[0123] The upper part of the cavity is diffused with gas C, which can be a gas with a low diffusion coefficient or an inert gas, such as one or more of H2, He, Ne, Ar, Kr, Xe, and N2. It can also contain etching gases, such as one or more of HCl, Cl2, and CF4. For SiC thin film epitaxy, carbon-containing gases such as C3H8 can also be used. H2 is preferred as the inert gas, and HCl is preferred as the etching gas. This diffused gas distribution not only protects the upper dome or upper liner 150 and 151, but also allows for etching and cleaning of existing additional thin films on the cavity walls of hot-wall or warm-wall equipment.

[0124] The cavity 300 can be a hot-wall cavity or a cold-wall cavity. When the cavity is a hot-wall cavity, the cavity wall or inner lining 150, 151 is composed of high-purity graphite material, or high-purity graphite coated with SiC or TaC, or high-purity quartz. When the cavity is a cold-wall cavity, the cavity wall or inner lining 150, 151 is composed of high-purity quartz material.

[0125] The base 103 on which the substrate 104 is placed is composed of high-purity graphite material, or high-purity graphite coated with SiC or TaC. The substrate 104 is placed on the base 103. To eliminate the non-uniformity of film formation in the airflow direction, the base 103 can also rotate the substrate 104 together at a certain speed, typically 0-100 rpm. This example only shows one base 103 and substrate 104, but it is also applicable to multiple bases or multiple substrates.

[0126] The opening 212 on the inner side of the cavity above the gas inlet (at gas B) for controlling the process gas boundary layer is shaped like a flared mouth, as shown in the figure. This shape facilitates the horizontal laminar flow of gas B into the cavity. Of course, the opening 212 can also be designed in other shapes that are conducive to laminar flow.

[0127] like Figure 3 and Figure 4 As shown, the inlet 201 of the main process gas A is located on the L side of the cavity, and the inlet of the main process gas A can be composed of multiple small inlets. Figure 3As shown, inlet 201 consists of small inlets 201A and 201B, which are located on the same horizontal plane, with their lower surfaces relatively close to the upper surface of substrate 104. When the main process gas flows along the Fp1 trace towards the side of cavity R, it should be essentially laminar flow within the cavity to ensure the stability of vapor deposition, especially epitaxial processes, and the quality of the thin film, preventing the occurrence of eddies. When the process gas is laminar, the reaction can only reach the inner walls of the cavity, such as the upper domes 150 and 151, through diffusion. This invention adds one or more layers of boundary layer-controlling gas B above the process gas, entering through inlet 210. Gas B can suppress the process gas, bringing it as close to the substrate as possible and reducing the thickness of the boundary layer near the substrate. It can also reduce or even prevent the upward diffusion of process gas A. Furthermore, the diffused layer gas C further protects the upper domes 150 and 151 more completely. Typically, the opening 210 is located above the horizontal centerline of the cavity, with a vertical distance from the substrate of approximately 1 / 2 to 4 / 5 of the cavity height. Figure 4 As shown, gas B flows primarily in a horizontal laminar state within the cavity, thus suppressing process gas A without disturbing its horizontal flow. The width of the gas B opening 210 is greater than or equal to the main process gas inlet 201, ensuring that gas B completely envelops process gas A. As shown in Figure 5, by adding the boundary layer control gas B and the diffuse purging gas C, the boundary layer thickness near the substrate is controlled and reduced compared to the existing configuration where only the main process gas flows.

[0128] The horizontal velocity of the main process gas A in the cavity ranges from 0.05 to 50 m / s. The horizontal velocity of gas B, used to control the process gas boundary layer, is approximately the same as that of gas A. The inlet velocity of the diffuse gas C is much smaller than the horizontal velocity of the process gas A, for example, 0.001 to 0.1 m / s, which reduces its impact on the flow of the lower gas B.

[0129] Because the boundary layer gas B and diffused gas C protect the cavity walls, the flow rate of the main process gas A can be appropriately increased. This increased flow rate, combined with a thinner boundary layer, allows more gaseous reactants to reach the substrate surface, increasing the gas-phase reaction rate by 1-3 times. For example, the SiC epitaxial deposition rate can reach 100-150 μm / min. Furthermore, the absence of unwanted additional deposited films on the cavity walls allows for longer processing times. Combined with faster deposition rates, thicker films can be deposited, especially epitaxial films, reaching thicknesses of 200-300 μm. Additionally, by increasing the use of gas B and diffused gas C, this invention solves the problem of additional film deposition on the cavity walls and reduces the height of the upper dome or upper liner 150. This reduces the vertical distance between the upper dome 150 and the substrate 104 to 1-4 mm, resulting in a smaller deposition cavity volume. This leads to a more uniform in-plane temperature distribution within the cavity, particularly at the base 103 and substrate 104, improving the quality and thickness uniformity of the epitaxial layer and enhancing the efficient utilization of process gases.

[0130] Figure 5A This diagram illustrates the gas velocity distribution within the reaction chamber when using an existing normal upper plate or dome. Figure 5B The diagram illustrates the gas velocity distribution within the reaction chamber when using a permeable upper plate or dome according to one embodiment of the present invention, and when permeable gas is injected into the reaction chamber. Figure 5C This diagram illustrates the gas flow lines within the reaction chamber when using an existing normal upperplate or dome. Figure 5D This diagram illustrates the gas flow path within the reaction chamber when using a permeable upper plate or dome according to one embodiment of the present invention, and when diffuse gas is injected into the reaction chamber. The permeable upper plate or dome is configured such that, in actual use, the vertical component of the diffuse gas velocity (relative to the direction of the main process gas) has virtually no vertical impact on the airflow along the upper edge of the substrate. In other words, the laminar flow state of the process gas remains unchanged, and the diffuse gas only affects the airflow within a certain range near the upper plate or dome.

[0131] Figure 11 A schematic diagram illustrating the principle of interface layer theory is shown. For example... Figure 11As shown, chemical vapor deposition on a substrate can be represented as interface layer transport above the substrate. Arrow X01 represents the fluid velocity vector at various vertical heights along the horizontal axis (distance x), V0 represents the maximum flow rate, and V... s δv represents the flow rate at the substrate surface, and δv represents the thickness of the interface layer.

[0132] Based on Reynolds number The thickness δ of the interface layer is calculated as follows:

[0133] δ=(x / Re x ) 1 / 2 .

[0134] Reynolds number The calculation can be expressed as the following formula:

[0135]

[0136] Where ρ g Represents the density of the airflow, v g The average velocity of the airflow, μ g This represents the dynamic viscosity of the airflow, and d represents the pipe diameter or characteristic dimension.

[0137] Average speed v g It can be calculated based on the gas flow rate Q, expressed as the following formula:

[0138] Q = JRT'

[0139]

[0140]

[0141] Where T′ represents the local temperature of the substrate, J represents the flow rate of the carrier gas, R represents the gas constant, and P tot A represents the total pressure, and A represents the cross-sectional area of ​​the cavity.

[0142] Based on the above calculations, the interface layer thickness can be expressed as follows:

[0143]

[0144] A first-order approximation is made, where the gas concentration gradient in the boundary layer is assumed to be linear, and the diffusion flux of the substrate is... Expressed as follows:

[0145]

[0146] Where P par Indicates gas partial pressure, P SThe gas surface pressure is represented by D, and the gas diffusion coefficient is represented by D. The gas phase reaction rate on the substrate depends on the mass transport at the substrate surface, that is, on the diffusion flux. Therefore, the parameter in the above formula can be increased by adjusting it. Reduce the boundary layer thickness to increase the reaction rate.

[0147] Figure 6 This diagram illustrates the effect of a diffused surface on a chemical vapor deposition process according to one embodiment of the present invention. U represents the horizontal flow rate of the process gas, d0 represents the distance between the substrate and the upper wall of the chamber, d1 represents the distance between the lower interface of the diffused surface and the substrate, and z represents the height of the diffused surface. The process gas flows into the reaction chamber, forming an upper interface layer below the upper wall of the chamber and a lower interface layer above the substrate. The process gas used in silicon epitaxy can be TCS, DCS, SiH4, or hydrogen. Figure 6 The medium-thick dashed line 601 represents the boundary between the upper and lower interface layers when a diffuse surface is formed on the upper wall 304 of the cavity. The thin dashed line 602 represents the boundary between the upper and lower interface layers when a diffuse surface is not formed on the upper wall of the cavity.

[0148] In the process chamber, let the cross-sectional area of ​​the chamber be A, and the total injection flow rate of the process gas per unit time be F. Then the flow velocity of the process gas can be expressed as: V avg =F / A;

[0149] Bed dwell time (relaxation time) can be expressed as: L / V avg L represents the length of the process cavity;

[0150] Additional injection diffusion area = injection velocity * average dwell time V plate Injection, the height of the diffuse surface at the outlet is Z = V plate *Tre=V plate *L*A / F.

[0151] The thickness of the lower interface layer can be expressed as follows:

[0152]

[0153] Where, μ g ρ represents the viscosity coefficient. g Let v represent the gas density, v represent the gas velocity, and x represent the horizontal coordinate.

[0154] When no diffuse surface is formed on the upper wall of the cavity, the process gas enters the cavity at a velocity of U and forms upper and lower interface layers. The thickness of the lower interface layer can be expressed by the following formula:

[0155]

[0156] When a diffusion channel is provided on the upper wall of the cavity, diffusion gas is injected through the diffusion channel to form a diffusion surface. The height of the diffusion surface can be expressed as d0-d1 (i.e., the characteristic dimension of the cavity at this point decreases from d0 to d0-d1). The originally laminar flow of the process gas is compressed, and the upper interface of the process gas is also the lower interface of the diffusion surface. The density of the process gas increases to... The flow rate of the process gas increases to The thickness of the lower interface layer can then be expressed as follows:

[0157]

[0158] In other words, when a diffuse surface is formed on the upper wall of the cavity, the thickness of the lower interface layer will become thinner than before.

[0159] The deposition rate of chemical vapor deposition (CVD) is limited by the chemical reaction rate and the concentration of reactant gases on the substrate. When the chemical reaction rate is sufficient, the deposition rate is mainly limited by the concentration of reactant gases on the substrate. The reactant gases on the substrate originate from the process gases that diffuse from the reaction chamber to the substrate and are affected by the diffusion flux.

[0160] According to Fick's First Law Where J represents the gas diffusion flux, C represents the concentration of the reacting gas in the cavity, and d represents the diffusion distance, it can be seen that the diffusion flux is proportional to the gas concentration. Therefore, when a diffuse surface exists, the thickness of the lower interface layer will become thinner than the original. The concentration gradient and diffusion flux of the gas also increase, which in turn increases the reaction rate and film formation rate on the substrate.

[0161] Furthermore, since the density of diffused gases, such as hydrogen, is generally lower than that of process gases, the diffused gases in the diffused layer will be suspended at d0-d1 below the upper wall of the cavity. This can inhibit the process gases from contacting the upper wall of the cavity and forming a film, which is beneficial for the chemical vapor deposition process and reduces the frequency of cavity maintenance.

[0162] Although various embodiments of the invention have been described above, it should be understood that they are presented by way of example only and not as limitations. It will be apparent to those skilled in the art that various combinations, modifications, and alterations can be made without departing from the spirit and scope of the invention. Therefore, the breadth and scope of the invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should be defined solely by the appended claims and their equivalents.

Claims

1. A vapor deposition apparatus, characterized in that, include: A cavity, in which a substrate is arranged; A first air inlet is arranged on a first side of the cavity, wherein the main process gas is configured to enter the cavity from the first air inlet and flow parallel to the substrate from the first side of the substrate to the second side. A second air inlet is arranged on the first side of the cavity and above the first air inlet, wherein auxiliary gas is configured to enter the cavity from the second air inlet; A first exhaust port is disposed on the second side of the cavity, wherein the first exhaust port is configured to exhaust the main process gas. as well as A second exhaust port is disposed on the second side of the cavity, wherein the second exhaust port is configured to discharge the auxiliary gas. Mass flow control is performed on at least one of the first exhaust port and the second exhaust port. The main process gas flows in laminar flow within the cavity. The auxiliary gas flows horizontally in a laminar flow state within the cavity, suppressing the main process gas and bringing it closer to the substrate. This reduces the boundary layer thickness of the main process gas, thereby minimizing its upward diffusion. The width of the second air inlet is greater than or equal to the width of the first air inlet, so that the auxiliary gas completely envelops the main process gas.

2. The vapor deposition apparatus according to claim 1, characterized in that, The auxiliary gas includes a suppressing gas, which includes an inert gas.

3. The vapor deposition apparatus according to claim 1, characterized in that, The exhaust rate of the second exhaust port is the same as the intake rate of the second intake port; or The exhaust rate of the second exhaust port is proportional to the intake rate of the second intake port, and the exhaust rate of the first exhaust port is proportional to the intake rate of the first intake port.

4. The vapor deposition apparatus according to claim 1, characterized in that, Also includes: An air pump is connected to the first exhaust port and the second exhaust port.

5. The vapor deposition apparatus according to claim 1, characterized in that, The ratio of the opening area of ​​the first exhaust port to the opening area of ​​the second exhaust port is the same as the ratio of the intake volume of the main process gas to the intake volume of the auxiliary gas.

6. The vapor deposition apparatus according to claim 4, characterized in that, Also includes: A throttle valve is connected to the first exhaust port and the second exhaust port, wherein the throttle valve is configured to control the exhaust rate of the first exhaust port and the second exhaust port so that the exhaust rate of the first exhaust port is the same as the intake rate of the main process gas, the exhaust rate of the second exhaust port is the same as the injection rate of the auxiliary gas, and the pressure of the cavity is maintained within a set pressure range.

7. The vapor deposition apparatus according to claim 1, characterized in that, Also includes: A third air inlet is disposed at the upper part of the cavity, wherein a third gas is configured to enter the cavity from the third air inlet.

8. The vapor deposition apparatus according to claim 7, characterized in that, The third gas is configured to be discharged through the second exhaust port.

9. The vapor deposition apparatus according to claim 7, characterized in that, Mass flow control is applied to at least one of the first exhaust port and the second exhaust port to allow the third gas and the auxiliary gas to be discharged from the second exhaust port.

10. The vapor deposition apparatus according to claim 9, characterized in that, The mass flow control includes: Flow rate is measured ultrasonically and converted to mass flow rate using pressure and temperature for control; and / or Quality control is achieved using a Coriolis mass flow meter, which measures based on the Coriolis force generated by the fluid flowing in a vibrating pipe, which is proportional to the mass flow rate.

11. The vapor deposition apparatus according to claim 1, characterized in that, The number of the first air inlets is m, and the number of the second air inlets is n, where both m and n are greater than or equal to 2.

12. The vapor deposition apparatus according to claim 11, characterized in that, Multiple first air inlets are arranged in parallel to control the distribution of gas within the cavity.

13. The vapor deposition apparatus according to claim 1, characterized in that, Also includes: A baffle plate is disposed on the first exhaust port and the second exhaust port. The baffle plate is movable, wherein the opening ratio of the first exhaust port and the second exhaust port is adjusted by moving the baffle plate to adapt to the ratio of the first air inlet to the second air inlet.

14. The vapor deposition apparatus according to claim 1, characterized in that, The auxiliary gas includes the main process gas, wherein the mass flow rate difference caused by the increase or decrease in the molar amount of the main process gas produced by the reaction is compensated.

15. The vapor deposition apparatus according to claim 9, characterized in that, Set n air inlets inj 1~n and n exhaust outlets exhaust 1~n. Express the air intake volume of the air inlets as ∑inj 1~n, and perform mass flow control on the exhaust outlets exhaust 1~(n-1).

16. The vapor deposition apparatus according to claim 7, characterized in that, Also includes: A third exhaust port is disposed on the second side of the cavity, wherein the third exhaust port is configured to discharge the third gas.

17. The vapor deposition apparatus according to claim 7, characterized in that, The third gas is configured to be discharged through the second exhaust port, wherein the exhaust volume of the first exhaust port is greater than the intake volume of the main process gas and less than the sum of the intake volumes of the main process gas and the auxiliary gas, and the exhaust volume of the second exhaust port is greater than the exhaust volume of the third gas and less than the sum of the intake volumes of the third gas and the auxiliary gas.

18. The vapor deposition apparatus according to claim 7, characterized in that, The second exhaust port is configured to provide negative pressure to the third gas so that the third gas gains upward energy.

19. The vapor deposition apparatus according to claim 18, characterized in that, The third gas is injected in sections to adjust the thickness of the boundary layer of the main process gas and to control the deposition rate at various points on the substrate.

20. The vapor deposition apparatus according to claim 1, characterized in that, The boundary layer height of the main process gas above the substrate near the second side of the cavity is controlled by adjusting the exhaust ratio of the first exhaust port and the second exhaust port.

21. The vapor deposition apparatus according to claim 1, characterized in that, Also includes: A fourth air inlet is arranged on the first side of the cavity, and the fourth air inlet is arranged below the first air inlet.

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