Injector, and substrate processing apparatus

Abstract

This disclosure relates to an injector configured for placement within a reaction chamber of a substrate processing apparatus to inject gas into the reaction chamber. The injector may be elongated along a first axis and has an internal gas conduction channel extending along the first axis, and includes at least one gas inlet opening and at least one gas outlet opening. The injector may have a width extending along a second axis perpendicular to the first axis, this width being substantially greater than the depth of the injector extending along a third axis perpendicular to both the first and second axes. The walls of the injector may have a varying thickness.

Description

Technical Field

[0001] This disclosure relates to an injector configured for placement within a reaction chamber of a substrate processing apparatus to inject gas into the reaction chamber. The injector may be substantially elongated along a first axis and has an internal gas conduction channel extending along this first axis, and is provided with at least one gas inlet opening and at least one gas outlet opening. The injector may have a width extending along a second axis perpendicular to the first axis, this width being substantially greater than a depth of the injector extending along a third axis perpendicular to both the first and second axes. Prior Technology

[0002] Substrate processing equipment (such as a vertical furnace) for processing substrates (e.g., semiconductor wafers) may include a heating element placed around a jar-shaped process tube. The higher end of the process tube may be closed, for example, by means of a dome-shaped structure, while the lower end surface of the process tube may be open.

[0003] The lower end can be partially closed by a flange. The interior defined by the process furnace tube and the flange forms a reaction chamber in which the wafer to be processed can be carried out. The flange may have an inlet opening for guiding a wafer-carrying boat into the reaction chamber. The wafer boat may be placed on a door, which is vertically movable and configured to close the inlet opening in the flange.

[0004] The flange may support one or more injectors to supply gas to the reaction chamber. For this purpose, the injector may be configured with an internal gas conduction channel. Additionally, a gas exhaust pipe may be provided in the flange. This gas exhaust may be connected to a vacuum pump for evacuating the gas from the reaction chamber. The gas supplied by the injector in the reaction chamber may be a reaction (process) gas for deposition reactions on the wafer. This reaction gas may also be deposited on other surfaces outside the wafer, for example, it may be deposited in the internal gas conduction channel. The layer built up by these deposits may cause injector blockage and / or breakage. Summary of the Invention

[0005] Therefore, an improved injector is needed.

[0006] In one embodiment, an injector may be provided configured for placement within a reaction chamber of a substrate processing apparatus to inject gas into the reaction chamber. The injector is substantially elongated along a first axis and has an internal gas conduction channel extending along the first axis and having at least one gas inlet opening and at least one gas outlet opening. The injector has a width extending along a second axis perpendicular to the first axis, the width being substantially greater than a depth extending along a third axis perpendicular to both the first and second axes. The walls of the injector have a varying thickness.

[0007] The various embodiments disclosed herein can be applied separately or in combination with each other. The embodiments disclosed herein will be further illustrated in the embodiments with reference to some examples shown in the drawings. Simple Explanation of the Diagram

[0008] It should be understood that the elements in the drawings are for simplification and clarity and are not necessarily drawn to scale. For example, the dimensions of some elements in the drawings may be exaggerated relative to other elements to help improve understanding of the embodiments illustrated in this disclosure. Figure 1 shows a cross-sectional view of the furnace tubes of a vertical furnace, including the injector; Figure 2 shows a schematic top view of the furnace tube in Figure 1; Figure 3 shows a cross-section of an injector according to one embodiment, which is used in the vertical furnace shown in Figures 1 and 2; Figures 4a to 4e schematically show an injector according to another embodiment for use in the vertical furnace of Figure 1; and, Figure 5 depicts the injectors shown in Figures 4a to 4e, configured in the furnace tube. Implementation

[0009] In this application, similar or corresponding features are represented by similar or corresponding element symbols. The description of various embodiments is not limited to the examples shown in the drawings and the element symbols used in the embodiments, and the scope of the claim is not intended to limit the description of the examples shown in the drawings.

[0010] Figure 1 shows a cross-sectional view of a vertical furnace. The vertical furnace may include a process furnace tube 12 and a heater H, the process furnace tube forming a reaction chamber and the heater being configured to heat the reaction chamber. A liner 2 may be provided along the process furnace tube 12, the liner 2 comprising a substantially cylindrical wall defined by a liner opening at a lower end and a dome-shaped top closure 2d at a higher end.

[0011] A flange 3 may be provided to at least partially close the opening of the process furnace tube 12. A door 14, configured in a vertically movable manner, may be configured to close the central inlet opening O in the flange 3 and to support the crystal boat B configured to hold the substrate W. The door 14 may be provided with a base R. The base R may be rotatable to allow the crystal boat B to rotate within the reaction chamber.

[0012] In the example shown in Figure 1, the liner 2 may include a substantially cylindrical liner wall having a substantially cylindrical outer surface 2a and a substantially cylindrical inner surface 2b. The flange 3 may be configured to at least partially close the pipe opening and the liner opening, which is more precisely defined by the lower end surface 2c of the liner 2. The flange 3 includes: An inlet opening O is configured to introduce and remove a crystal boat B, which is configured to carry a substrate W in the reaction chamber I of the liner 2; Gas inlet 16, which is used to supply gas F (e.g., process gas) to reaction chamber I; and, Gas discharge pipe 7 is used to remove gas from reaction chamber I.

[0013] The substrate processing apparatus may have a container for containing silicon precursors and may be operatively connected to an elongated injector 17 via a gas inlet 16. The injector 17 may be constructed and configured to extend vertically toward its higher second end along the substantially cylindrical wall of the liner 2 into the reaction chamber I. The injector may be supported by a flange 3 at its lower first end and may include an injector opening for injecting gas into the reaction chamber. One or more injectors 17 may be used to supply process gases to the reaction chamber I. Figure 2 shows one injector 17.

[0014] A gas discharge pipe 7 for removing gas from reaction chamber I can be constructed and positioned below injector opening 18. In this way, a downward flow F can be established in the reaction chamber of liner 2. This downward flow F can transport contaminants of reaction byproducts and particles from substrate W, boat B, liner 2, and / or support flange 3 downward to discharge pipe 7 away from the treated substrate W.

[0015] A gas discharge pipe 7 for removing gas from reaction chamber I can be provided below the liner opening of liner 2. This can be advantageous since the source of contamination in the reaction chamber can be formed by the contact between liner 2 and flange 3. Again, the downward flow F can transport particles from the liner / flange interface downwards to the discharge pipe away from the treated substrate.

[0016] The gas discharge opening 8 can be constructed and positioned between the liner 2 and the flange 3 to remove gas from the circumferential space between the liner 2 and the furnace tube 12. In this way, the pressure in the circumferential space can be equalized with that in the internal space I, and the pressure in the low-pressure vertical furnace can be lower than the atmospheric pressure surrounding the furnace tube 12. The vertical furnace can be equipped with a pressure control system to remove gas from the reaction chamber.

[0017] In this way, since atmospheric pressure compensation is not required, the liner 2 can be made quite thin and constructed from a relatively weak material. This creates greater freedom in the selection of materials for the liner 2. The thermal expansion of the liner 2 material can be selected to be comparable to that of the material deposited on the substrate in the reaction chamber. The latter has the advantage that the expansion of the liner and the expansion of the material also deposited on the liner can be the same. This minimizes the risk of deposited material falling off due to temperature changes in the liner 2.

[0018] Since it may be necessary to compensate for atmospheric pressure relative to the low pressure inside the furnace tube, the furnace tube 12 can be made quite thick and constructed from a material with relatively high compressive strength. For example, the low-pressure furnace tube 12 can be made of quartz with a thickness of 5 to 8 mm, preferably approximately 6 mm. Quartz has a density of 0.59 × 10⁻⁶ mm. [, -6 , ]K [, -1 The very low coefficient of thermal expansion (CTE) of SiN4 (see Table 1) makes it more resilient to thermal fluctuations in equipment. While the coefficient of thermal expansion of deposited materials can be higher (e.g., CTE = 3 × 10⁻⁶ for Si₃N₄), its very low coefficient of thermal expansion makes it easier to handle thermal fluctuations in equipment. [] K -1, CTE of Si = 2.3 × 10 -6 K -1), the difference can be relatively small. However, when the film is deposited onto a furnace tube made of quartz, the film can still adhere even when the furnace tube is subjected to many large thermal cycles, which may increase the risk of contamination.

[0019] The liner 2 prevents any deposits from falling onto the inner side of the furnace tube 2, and thus reduces the risk of deposits falling off the furnace tube 12. Therefore, the furnace tube can be made of quartz.

[0020] The silicon carbide (SiC) substrate 2 (CTE = 4 × 10⁻⁶ K⁻¹) can provide an even better match in coefficients of thermal expansion between the deposited film and the substrate, resulting in a greater cumulative thickness before the deposited film may need to be removed from the substrate. Mismatches in coefficients of thermal expansion lead to cracking and peeling of the deposited film, as well as a corresponding high particle number, which are undesirable and can be mitigated by using the SiC substrate 2. The same mechanism can operate for the injector 17; however, the injector 17 may break if too much material with different thermal expansion is deposited. Therefore, it may be advantageous for the injector 17 to be made of silicon carbide or silicon. Table 1 Coefficient of thermal expansion (CTE) of materials in semiconductor processing Material Thermal expansion (ppm / K) quartz 0.59 Silicon nitride 3 Silicon 2.3 Silicon carbide 4.0 Tungsten 4.5

[0021] Whether a material is suitable for the liner 2 and / or injector 17 depends on the material being deposited. Therefore, it is advantageous to use materials with substantially the same thermal expansion for both the deposited material and the liner 2 and / or injector 17. Thus, it may be advantageous to use materials with a relatively higher thermal expansion than quartz for the liner 2 and / or injector 17; for example, silicon carbide (SiC) may be used. The silicon carbide liner may be between 4 and 6 mm thick, preferably 5 mm, since it does not require atmospheric pressure compensation. Pressure compensation can be achieved using furnace tubes.

[0022] For systems that deposit metals and metal compounds (such as TaN, HfO2, and TaO5) with a coefficient of thermal expansion between about 4 × 10⁻⁶ K⁻¹ and 6 × 10⁻⁶ K⁻¹, the materials of the liner and injector preferably have a coefficient of thermal expansion between about 4 × 10⁻⁶ K⁻¹ and 9 × 10⁻⁶ K⁻¹ (including, for example, silicon carbide).

[0023] For the deposition of materials with even higher coefficients of thermal expansion, the materials of the liner and / or injector may be selected, for example, those described in Table 2. Table 2 Coefficient of thermal expansion (CTE) of ceramic structural materials Material Thermal expansion (ppm / K) Machinable ceramics (Macor) 12.6 Boron nitride 11.9 Ordinary glass 9 Mullite 5.4

[0024] A purge gas inlet 19 is provided within the furnace tube 12 to supply purge gas P to the circumferential space S between the outer surface 2b of the liner and the process furnace tube 12. The purge gas inlet includes a purge gas injector 20, which extends vertically from the flange 3 toward the top of the liner along the outer surface of the cylindrical wall of the liner 2. The purge gas P to the circumferential space S can establish flow in the gas discharge opening 8 and counteract the diffusion of process gas from the discharge pipe 7 to the circumferential space S, as depicted by the arrow.

[0025] The flange 3 may have an upper surface. The liner 2 may be supported by support members 4, which are connected to the cylindrical outer surface 2a of the liner wall and each has a downwardly guiding support surface. The liner may also be directly supported on the upper surface of the flange 3 by its lower surface 2c, while accommodating the gas discharge opening 8 between the upper surface and the liner 2.

[0026] The support surface of the support member 4 can be radially outwardly positioned from the cylindrical inner surface 2b of the liner 2. In this example, the support surface of the support member 4 can also be radially outwardly positioned from the cylindrical outer surface 2a of the liner 2 to which it is attached. The downwardly guiding support surface of the support member 4 can contact the upper surface of the flange 3 and support the liner 2, while accommodating the gas discharge opening 8 between the upper surface and the liner 2.

[0027] The supporting flange 3 of the closure may include gas discharge openings 8 to remove gas from the reaction chamber of the liner 2 and the circumferential space between the liner 2 and the low-pressure furnace tube 12. At least some of the gas discharge openings 8 may be provided between the upper surface of the flange 3 and the liner 2. At least some of the gas discharge openings may be provided near the liner opening. The gas discharge openings 8 may be fluidly connected to a pump via a discharge pipe 7 for extracting gas from the reaction chamber and the circumferential space between the process furnace tube 12 and the liner 2.

[0028] Figure 2 is a schematic top view of the furnace tube in Figure 1. The figure shows a liner 2 with a cylindrical wall that defines a substantially cylindrical inner surface 2b and a substantially cylindrical outer surface 2a, the surfaces forming openings 13 for inserting a crystal boat configured to carry a substrate.

[0029] Support members 4 are also visible. In this example, the liner 2 has three support members 4, which are equally spaced along the circumference of the cylindrical outer surface 2a of the liner 2. The flange may be provided with positioning protrusions 5, which extend upward from the upper surface 3a of the flange. The positioning protrusions 5 can engage the support members 4 on their tangential end faces. As a result, the positioning protrusions 5 have the function of centering the liner 2 relative to the support flange 3.

[0030] The liner 2 and the recess forming the support member 4 may be made of quartz, silicon, or silicon carbide. The liner 2, which demarcates the reaction chamber, may have radially outwardly extending protrusions 2e to accommodate the injector 17 or a temperature measurement system in the reaction chamber.

[0031] Figure 3 schematically shows a cross-section of an injector 17 according to one embodiment, used in the vertical furnace of Figures 1 and 2. The injector 17 can be configured to be disposed within the reactor of the vertical furnace to inject gas into reaction chamber I. The injector 17 may be configured with an internal gas conduction channel 20 for conveying gas. The injector 17 may be substantially elongated along a first axis, and the internal gas conduction channel 20 may extend along the first axis.

[0032] The injector 17 may have a width extending along a second axis X perpendicular to the first axis, this width being substantially greater than a depth extending along a third axis Y perpendicular to both the first and second axes. The wall 22 of the injector 17 may have a varying thickness. The wall 22 of the injector 17 may have a varying thickness along the second axis X. The varying thickness of the wall 22 may vary between 10% and 60%. For example, a 40% variation, as depicted, from 2.5 mm to 3.5 mm.

[0033] The internal gas conduction channel 20 of the injector 17 may have a substantially elliptical cross-section. The width of the internal gas conduction channel 20 along its second axis X may be substantially greater than its depth along its third axis Y. The substantially elliptical cross-section may be constructed from a plurality of circles with fixed radii to accommodate drilling and grinding. Rounded corners also prevent the accumulation of stress and contamination in the corners. The radius of the circles may be from 1 mm to 10 mm, for example, a circle with a radius of 5 mm. The horizontal internal cross-sectional area of ​​the internal gas conduction channel 20 inside the injector 17 may be between 100 mm² and 1500 mm², preferably between 200 mm² and 500 mm², and most preferably between 250 mm² and 350 mm².

[0034] Essentially, the elliptical gas conduction channel 20 can be partially pinched off in the middle. This pinching means that the internal gas conduction channel 20 has a smaller depth in the third direction. The middle refers to the middle of the width of the injector 17 in the second direction X. The pinching can be accomplished by a wall 22 with varying thickness. For example, by the wall 22 having an increased thickness in the middle of its width, the gas conduction channel 20 is pinched off.

[0035] The essentially elliptical gas conduction channel 20 can be pinched at the midpoint of the second direction by a spherical portion 24, which thickens the wall 22 and extends into the gas conduction channel 20 and pinches it. The surface of the spherical portion 24 can be partially shaped like a spherical circle. The spherical circle can have a constant radius relative to an axis parallel to the first axis. The radius can be between 10 mm and 50 mm, preferably between 15 mm and 30 mm, and as depicted, it can be 23 mm.

[0036] The wall 22 of the injector 17 may have a varying thickness along the third axis Y. The varying thickness along the third axis Y may be a relatively small variation of about 7 mm.

[0037] The wall 22 of the injector 17 can have a varying thickness along the second and third axes X and Y across the circumference. The varying thickness of the wall 22 can be between 4% and 60%.

[0038] The wall 22 of the injector 17 may have varying thickness along the substantial portion of the first axis. In this way, its strength can be increased where necessary.

[0039] The injector 17 may have a gas outlet opening 25. The gas outlet opening 25 may have a radius of 3 mm to 15 mm, preferably between 4 mm and 10 mm, and most preferably between 5 mm and 9 mm, for example 8 mm.

[0040] Figures 4a through 4e schematically show injectors 17a, 17b, and 17c according to another embodiment for use in the vertical furnaces of Figures 1 and 5. Injectors 17a, 17b, and 17c in Figures 4a through 4e can each be specially configured to provide process gas at a specific height within reaction chamber I. Therefore, injectors 17a, 17b, and 17c in Figures 4a through 4e can be optimized for synergistic cooperation, as depicted in Figure 5. Alternatively, each injector 17 can be used individually, as depicted in Figure 2. Injectors 17a, 17b, and 17c can be substantially elongated along the first axis Z.

[0041] Injectors 17a, 17b, and 17c may be configured with internal gas conduction channels 20 for conveying process gases. The internal gas conduction channels 20 may extend along a first axis Z. The internal gas conduction channels 20 of injectors 17a, 17b, and 17c may have a substantially elliptical cross-section.

[0042] The internal gas conduction channel 20 may extend along the second axis X between 10 mm and 50 mm, preferably between 20 mm and 30 mm, for example, about 25 mm. The extension of the internal gas conduction channel 20 along the second axis X may be substantially greater than the extension of the channel along the third axis Y. The internal gas conduction channel 20 may extend along the third axis Y between 8 mm and 30 mm, preferably between 10 mm and 20 mm, for example, about 12 mm.

[0043] In essence, the elliptical cross-section can be constructed from a circle with a radius of 1 mm to 10 mm, for example, a circle with a radius of 5 mm. Because the corners will then have a minimum roundness of 1 mm to 10 mm, for example, 5 mm, this avoids straight corners in the gas conduction channel 20.

[0044] The horizontal cross-sectional area of ​​the internal gas conduction channel 20 inside the injector 17 can be between 100 square millimeters and 1500 square millimeters, preferably between 200 square millimeters and 500 square millimeters, and most preferably between 250 square millimeters and 350 square millimeters.

[0045] Essentially, the elliptical gas conduction channel 20 can be partially pinched in the middle. This pinching means that the internal gas conduction channel 20 is smaller in the third direction Y. The middle refers to the middle of the width relative to the injectors 17a, 17b, 17c in the second direction X. The pinching can be accomplished by a wall 22 with increased thickness in the middle.

[0046] The elliptical gas conduction channel 20 can be partially pinched at the midpoint in the second direction by a sphere 24 disposed on the wall 22 and extending into the gas conduction channel 20. The surface of the sphere 24 can be partially shaped like a circle. The circle can have a constant radius relative to an axis parallel to the first axis. The radius can be between 10 mm and 50 mm, preferably between 15 mm and 30 mm, and as depicted, it can be 23 mm.

[0047] Injectors 17a, 17b, and 17c may have a width extending along a second axis X perpendicular to the first axis, which is substantially greater than the depth of the injector extending along a third axis Y perpendicular to both the first and second axes, as depicted in Figure 4c. The wall 22 of injectors 17a, 17b, and 17c may have a varying thickness.

[0048] The walls 22 of injectors 17a, 17b, and 17c may have varying thickness along the third axis Y. The walls 22 of injectors 17a, 17b, and 17c may have varying thickness across their circumference along the second axis X and the third axis Y. The walls 22 of injectors 17a, 17b, and 17c may have varying thickness along the substantial portion of the first axis X.

[0049] Injectors 17a and 17b can be so-called multi-hole injectors, and have a plurality of gas outlet holes 25 of equal length in the direction of the second end 23 relative to the first end 21, as shown in Figures 4a and 4b. The gas outlet openings 25 can have a radius of 3 mm to 15 mm, preferably between 4 mm and 10 mm, and most preferably between 5 mm and 9 mm, for example, 6 mm. The longer injector 17a of the plurality of injectors 17a, 17b, and 17c can have a plurality of gas outlet holes 25, as depicted in Figure 4a, and can extend internally to approach the top closure 2d of the closing liner 2 (Figures 1 and 5). The shorter injector 17b of the plurality of injectors 17a, 17b, and 17c can have a plurality of gas outlet holes 25, as depicted in Figure 4b, and extend to the middle of the boat B.

[0050] The size of the gas conduction channel 20 can be reduced at the first end 21, wherein the injectors 17a, 17b, and 17c can be connected to the gas inlet 16 near the flange 3. Since the temperature near the first end 21 is lower, less process gas is deposited in the internal channel 20 near the first end 21.

[0051] The depth of injectors 17a, 17b, and 17c in the third direction Y can decrease toward the second end 23. The injector extending within the interior I to the top closure 2d near the closing liner 2 can have a shape in which, in Figure 1, the dimension in the radial direction decreases as it approaches the top closure.

[0052] The injectors 17a, 17b, and 17c in Figures 4a to 4e can each be specially configured to provide process gas at a specific height in reaction chamber I. Therefore, at least one of the injectors 17a, 17b, and 17c can have different lengths.

[0053] As depicted in Figures 4a and 4e, the longer injectors 17a and 17c of the plurality of injectors 17 may extend within the interior I to approach the top closure 2d of the closing liner 2, as depicted in Figures 1 and 5. The longer injector 17c of the plurality of injectors 17a, 17b, and 17c may have a single gas outlet port 25 at its second end 23, as depicted in Figure 4d. This injector may be referred to as a tilt-type injector 17c, which closes along its elongated length to have only a single process gas outlet at its second end 23. Figure 4e depicts a cross-section of this tilt-type injector, which has the same properties as described above with respect to Figure 4c, except that it lacks a gas outlet port 25 on the side.

[0054] The single gas outlet orifice 25 at the second end 23 of the tilt-type injector can have the same properties as described above with respect to Figure 4c. The single gas outlet orifice 25 of the tilt-type injector can be between 100 mm² and 1500 mm², preferably between 200 mm² and 500 mm², and most preferably between 250 mm² and 350 mm². Therefore, the injectors 17a, 17b, and 17c of Figures 4a to 4e can be optimized to work together, as depicted in Figure 5.

[0055] Figure 5 illustrates how the injectors 17a, 17b, and 17c of Figures 4a to 4e can be configured in furnace tube 2. Injectors 17a and 17b can be porous injectors (see Figures 4a and 4b) having a series of outlet openings 25 extending elongated along the injectors 17a and 17b to deliver gas through conduction channels into reaction chamber I. The shorter injector 17b and / or the longer injector 17a among the plurality of injectors 17a, 17b, and 17c can have multiple gas outlet holes 25. The outlet openings 25 can be substantially circular. The series of outlet openings 25 can be aligned along a line above the surface of the porous injectors 17a and 17b.

[0056] The outlet opening 25 can be configured to allow gas to be injected in at least two different directions substantially perpendicular to the elongated direction of the porous injector, in order to improve the mixing of process gases in reaction chamber I. The series of openings 25 can thus be aligned along at least two lines above the surface of the injector 17. Although the first line with openings is shown in Figures 4a and 4b, a similar second line with openings 25 can be configured on the other side of the injector 17, as depicted in Figure 5. The series of openings 25 along the first line can be configured to allow gas to be injected in a first direction, and the series of openings 25 along the second line can be configured to allow gas to be injected in a second direction. The first and second directions can be at an angle between 30 degrees and 180 degrees to each other.

[0057] The outlet openings 25 may be provided in pairs at the same height, as depicted in Figure 5. Alternatively, the outlet openings 25 may be provided in pairs at unequal heights to improve the strength of the injector 17. The two outlet openings may inject gas in both directions (e.g., at an angle of approximately 90 degrees) to improve radial uniformity.

[0058] In Figures 4a and 4b, the distance between the openings 25 of the series of openings can be constant as the process advances from the first end 21 to the second end 23 of the multi-hole injector 17. Advantageously, each outlet opening 25 can have substantially equal flow of process gas through it.

[0059] The distance between the outlet openings 25 of the series of outlet openings can also be designed so that this distance decreases as the multi-hole injector 17 moves from the first end 21 to the second end 23. The latter can help compensate for the pressure loss when the process gas is delivered from the first end 21 to the second end 23.

[0060] The area of ​​the outlet opening of the porous injector can be between 1 square millimeter and 200 square millimeters, preferably between 7 square millimeters and 100 square millimeters, and even more preferably between 13 square millimeters and 80 square millimeters. A larger opening has the advantage that it takes longer for the opening to become clogged due to deposits within it. The number of outlet openings 25 can be between 2 and 40, preferably between 3 and 30, and even more preferably between 5 and 15.

[0061] The longer of the plurality of injectors 17a, 17b, and 17c may have a single gas outlet at its second end, as depicted in Figure 4d. This injector 17c may be referred to as a tilt-type injector 17c, which closes along its elongated length to have only a single process gas outlet at its second end near the top closure 2d of the liner. The single gas outlet at the second end of the tilt-type injector may have the same properties as described above with respect to Figures 4d and 4e.

[0062] The outlet opening 25 of the gas injector 17 can be configured to reduce clogging. The outlet opening may have a concave shape from the inside to the outside. The concave shape, where the surface area of ​​the opening on the inner surface of the injector is larger than the surface area of ​​the outlet opening 25 on the outer surface of the injector, reduces clogging. The larger area on the inner side allows for more deposition, where the pressure is higher, and thus the deposition rate is greater. On the outer side, the pressure is lower, therefore deposition is slower, and the smaller area may collect the same amount of deposition as the larger diameter on the inner side.

[0063] Reducing the pressure inside the injector may decrease the reaction rate within injector 17, as reaction rates typically increase with increasing pressure. An additional advantage of the low pressure inside the injector is that the gas volume through the injector expands at low pressure, and for a constant source gas flow, the residence time of the source gas inside the injector is correspondingly reduced. This combination of factors reduces source gas decomposition, thereby also reducing deposition within the injector.

[0064] Process gases for depositing layers on wafer W in boat B can be injected via injector 17 in reaction chamber I, or deposited in the internal gas conduction channel or on the outer surface of injector 17. This deposition can cause tensile or compressive stress in injector 17. This stress can cause injector 17 to break, resulting in downtime of the vertical furnace and / or damage to wafer W. Less deposition in the injector can thus extend the life of injector 17 and make the vertical furnace more economical.

[0065] Temperature variations in the injector 17 can even increase these stresses. To mitigate stress, the injector can be made of a material with a coefficient of thermal expansion similar to that of the material deposited by the process gas. For example, if silicon nitride is deposited, the gas injector can be made of silicon nitride; if silicon is deposited, it can be made of silicon; or when silicon oxide is deposited by the process gas, it can be made of silicon oxide. The thermal expansion of the deposited layer within the injector can thus be better matched to the thermal expansion of the injector, reducing the chance that the gas injector may break during temperature changes.

[0066] Silicon carbide can also be a suitable material for injector 17. Silicon carbide has thermal expansion properties that can match many deposited materials.

[0067] One disadvantage of the low pressure inside the injector is that the conduction of the injector is significantly reduced. This will result in poor distribution of the source gas flow over the opening pattern across the length of the injector: most of the source gas will flow out from the orifice near the inlet end of the injector.

[0068] To facilitate the flow of process gas along the length of the injector, the injector may be provided with an internal gas conduction channel with a large internal cross-section. In order to accommodate the injector according to this disclosure inside the reaction chamber, the tangential size of the injector 17 may be greater than its radial size, and the liner 2 may be provided with an outwardly extending protrusion to accommodate the injector.

[0069] In one embodiment, the two source gases providing the two constituent elements of the binary membrane are mixed in the gas supply system before entering the injector. This is the simplest way to ensure a homogeneous composition of the injected gas across the length of the crystal boat. However, this is not necessary. Alternatively, the two different source gases can be injected via separate injectors and mixed after injection into the reaction chamber.

[0070] Using two injector branches allows for some tuning possibilities. When gases of substantially the same composition are supplied to two parts of the injector via separate source gas supplies, the flows supplied to the different injector branches can be selected differently to fine-tune the uniformity of the deposition rate across the crystal boat. Alternatively, gases of different compositions can be supplied to the two lines of the injector to fine-tune the composition of the binary film across the crystal boat. However, optimal results are achieved when the composition of the injected gas is identical for both injector lines.

[0071] Since the injector 17 can be supported by the flange 3 at its first end 21, the injector 17 may swing slightly at its second end 23 because it is a very long and thin structure, as depicted in Figure 1. Therefore, it is desirable or necessary to design the liner 2, the injector 17, and the crystal boat B such that there is sufficient space between them.

[0072] The outer wall of the injector 17 may taper towards the second end 23 of the injector, spanning at least 10%, preferably 30%, more preferably 50%, and even more preferably 100% of its length. By tapering the injector 17 at the second end 23, it occupies less space in the small space between the liner 2 and the crystal boat, where the clearance is tightest, near the second end 23 in the reaction chamber I. Therefore, the clearance at the location where the injector 17 with the tapered second end 23 can be positioned in the small space can be slightly more accommodating.

[0073] Therefore, the injector extending internally to the top closure 2d near the closed liner can have a shape whose dimensions in the radial direction decrease as it approaches the top closure. Furthermore, in a vertical furnace without the liner 2, an injector 17 with a gradually tapering shape at its second end 23 can be used to allow for a looser positioning clearance between the injector and the furnace tube and the crystal boat.

[0074] Injector 17 may include multiple branches (e.g., two branches), each with a separate gas feed conduit connection. One branch injects process gas into the lower portion of the reaction chamber, and the other branch injects process gas into the upper portion of the reaction chamber. The branches may be connected by a connecting portion. However, including two or more injector branches is not necessary for this disclosure. The branches may taper partially at a second end.

[0075] The injector 17 can be made of ceramic. The ceramic can be selected from silicon carbide (SiC), silicon oxide (SiOx), silicon, or aluminum oxide (AlOx). The injector can be manufactured by first forming the injector and then baking the injector to harden the ceramic.

[0076] Ceramic-leading polymers can be used as precursors, which can form ceramic products through thermal decomposition at temperatures ranging from 1000°C to 1100°C. Precursor materials for obtaining silicon carbide in this manner may include polycarbosilanes, poly(methylsilanediene), and polysilazanes. Silicon carbide materials obtained through the thermal decomposition of ceramic-leading polymers are known as polymer-derived ceramics (PDCs).

[0077] The thermal decomposition of ceramic-leading polymers is most often carried out at relatively low temperatures in an inert atmosphere. This method is advantageous because the polymer can be formed into various shapes before thermally decomposing into ceramic silicon carbide. Prior to thermal decomposition, the material is softer and therefore easier to shape.

[0078] The injector 17 may include a bottom portion connected to a top portion, wherein the top portion may taper slightly at a second end 23 and terminate thereafter. The length of the bottom portion from the first end 21 may be between 30 cm and 40 cm, and may be substantially straight.

[0079] The bottom portion may be provided with a connecting tube 27 (see Figures 4a and 4b). The connecting tube 27 can be fitted into a hole in the flange 3 (Figure 1) to position and hold the injector 17. Such a configuration on the first end 21 of the injector can be advantageous if the injector is heated, as it allows the injector 17 to expand. A disadvantage may be that it allows some wobbling of the injector 17, especially at the second end 23.

[0080] By gradually narrowing the second end 23, the clearance for the oscillation of the injector 17 can be increased. The top portion at the second end 23 may have a cross-sectional area that is 1% to 80%, more preferably 3% to 40%, and most preferably 4% to 20% smaller than that at the first end. The top portion at the second end may have a wall thickness that is 2% to 50%, more preferably 5% to 30%, and most preferably 10% to 20% larger than that at the first end 21.

[0081] The injector 17 may have a cross-sectional area at the second end that is 1% to 80%, preferably 3% to 40%, and most preferably 4% to 20% smaller than that at the first end. The injector at the second end 23 may have a wall thickness that is 2% to 50%, preferably 5% to 30%, and most preferably 10% to 20% smaller than that at the first end 21.

[0082] While specific embodiments have been described above, it will be understood that this disclosure may be practiced in ways other than those described. The description above is intended to illustrate and not limit. Therefore, those skilled in the art will understand that modifications may be made to the disclosure described above without departing from the scope of the claims set forth below. Various embodiments may be used in combination or independently of each other.

[0083] 2: Liner 2a: Cylindrical outer surface 2b: Cylindrical inner surface 2c: Surface 2d: Top closure 2e: Protruding part 3: Flange 3a: Upper surface 4: Supporting components 5: Protrusion 7: Gas exhaust pipe 8: Gas exhaust opening 12: Process furnace tube 13: Opening 14: Door 16: Gas Inlet 17: Injector 17a, 17b, 17c: Injector 18: Injector opening 19: Purge gas inlet 20: Internal gas conduction channel 21: First end 22: wall 23: Second end 24: Ball Section 25: Gas outlet opening, gas outlet hole 27: Connecting pipe B: Crystal Boat F: Gas, flow H: Heater I: Reaction chamber, internal space O: Entrance opening P: Purge gas R: Base S: Circumferential space W: substrate X: Second axis Y: Third axis

Claims

1. An injector configured to be disposed in a reaction chamber of a substrate processing apparatus for injecting gas into the reaction chamber, the injector being substantially elongated along a first axis and having an internal gas conduction channel extending along the first axis and having at least one gas inlet opening and at least one gas outlet opening, and the injector having a width extending along a second axis perpendicular to the first axis, the width being substantially greater than a depth extending along a third axis perpendicular to both the first axis and the second axis, wherein the wall of the injector has a varying thickness, and wherein the internal gas conduction channel has a substantially elliptical cross-section, whereby the extension of the internal gas conduction channel along the second axis is substantially greater than the extension of the internal gas conduction channel along the third axis, wherein the substantially elliptical cross-section is partially pinched at the midpoint of the second axis by the wall having an increased thickness.

2. The injector of claim 1, wherein the wall of the injector has a varying thickness along the second axis.

3. The injector of claim 1, wherein the wall of the injector has a varying thickness along the third axis.

4. The injector of claim 1, wherein the wall of the injector has a varying thickness across its circumference along the second axis and the third axis.

5. The injector of claim 1, wherein the wall of the injector has a varying thickness along a portion of the first axis.

6. The injector of claim 5, wherein the substantially elliptical cross-section is partially pinched at the midpoint of the second axis by a ball provided to the wall and extending into the internal gas conduction channel.

7. The injector of claim 6, wherein the surface of the ball portion is partially shaped as a circle, the circular shape having a constant radius relative to an axis parallel to the first axis.

8. The injector of claim 1, wherein the injector has a gas inlet opening at a first end of the injector.

9. The injector of claim 8, wherein the injector has a single gas outlet opening at a second end opposite to the first end.

10. The injector of claim 8, wherein the injector has a plurality of gas outlet holes along its length in a direction of a second end opposite to the first end.

11. The injector of claim 1, wherein the depth of the injector on the third axis decreases toward the second end.

12. The injector of claim 1, wherein the horizontal cross-sectional area of ​​the internal gas conduction channel on the inner side of the injector is between 100 square millimeters and 1500 square millimeters.

13. A substrate processing apparatus comprising: a furnace tube; a closure liner configured to extend within the interior of the furnace tube; a gas injector for supplying a gas to the interior of the furnace tube; and a gas discharge pipe for removing gas from the interior, wherein the closure liner comprises: a substantially cylindrical wall defined by a liner opening at a lower end, a top closure at a higher end, and the closure liner substantially closed over the liner opening for gas, wherein the gas injector is a gas injector as claimed in claim 1.

14. The substrate processing apparatus of claim 13, wherein the substrate processing apparatus further comprises a plurality of injectors, and at least one of the injectors has a different length.

15. The substrate processing apparatus of claim 14, wherein the longest of the plurality of injectors extends within the interior to approach the top closure of the closing liner.

16. The substrate processing apparatus of claim 14, wherein one of the longest of the plurality of injectors has a single gas outlet orifice.

17. The substrate processing apparatus of claim 14, wherein one of the longest of the plurality of injectors has a plurality of gas outlet holes.

18. The substrate processing apparatus of claim 14, wherein the shortest of the plurality of injectors has a plurality of gas outlet holes.

19. The substrate processing apparatus of claim 13, wherein the liner is substantially cylindrical and the horizontal inner cross-sectional area of ​​the internal gas conduction channel inside the injector has a shape having a dimension in a direction tangent to the circumference of the substantially cylindrical liner that is greater than its dimension in the radial direction.

20. The substrate processing apparatus of claim 19, wherein the injector extends within the interior to approach one of the top closures of the closing bushing, and has a shape whose dimension in the radial direction decreases as it approaches the top closure.

21. The substrate processing apparatus of claim 13, wherein the liner is supported on a flange and a gas discharge opening is configured and arranged between the liner and the flange for removing gas from the circumferential space between the liner and the furnace tube to the gas discharge pipe.

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