Slot-die type gas distribution device for photovoltaic manufacturing

Abstract

A slot-die type gas distribution device for photovoltaic manufacturing is provided. The slot-die type gas distribution device includes a first gas distribution device (105) at a process chamber inlet (104) and a second gas distribution device (13) at a process chamber outlet (11). The first gas distribution device (105) is connected to the process chamber inlet (104) through a flat quadrangular first communication device (9), and the second gas distribution device (13) is connected to the process chamber outlet (11) through a flat quadrangular third communication device (12). The device effectively improves the gas distribution uniformity in the process chamber.

Claims

1. A slot-die type gas distribution device for photovoltaic manufacturing, comprising a first gas distribution device, wherein the first gas distribution device is provided with a first inlet and a first outlet; the first gas distribution device comprises a first gas distribution tube; the first inlet is arranged at a top of the first gas distribution tube, so that a flow direction of gas passing through the first inlet is perpendicular to a bottom surface of the first gas distribution tube, and the top of the first gas distribution tube is a highest position of the first gas distribution tube from the ground; the first inlet is arranged at a center of the top of the first gas distribution tube; wherein the first gas distribution tube is semicircular; and the first gas distribution tube includes a first rectangular plane and a first curved surface; the first rectangular plane is located beneath the first curved surface and is parallel to the ground; and the first inlet is arranged on the first curved surface, and a height of the first inlet from the first rectangular plane is a radius of the first gas distribution tube.

2. The slot-die type gas distribution device for photovoltaic manufacturing according to claim 1, wherein a position of the first outlet is lower than that of the first inlet.

3. The slot-die type gas distribution device for photovoltaic manufacturing according to claim 1, wherein the first outlet is arranged along a length direction of the first gas distribution tube; a length of the first outlet is equal to that of the first gas distribution tube.

4. The slot-die type gas distribution device for photovoltaic manufacturing according to claim 1, wherein the first gas distribution device comprises m (m is greater than or equal to 2) first gas distribution tubes, which are communicated in sequence, and each two adjacent first gas distribution tubes are communicated, so as to implement gas distribution processes multiple times; the first inlet is arranged on the first gas distribution tube at a starting end, and the first outlet is arranged on the first gas distribution tube at a tail end.

5. The slot-die type gas distribution device for photovoltaic manufacturing according to claim 4, wherein the m first gas distribution tubes have the same size.

6. The slot-die type gas distribution device for photovoltaic manufacturing according to claim 1, wherein the first inlet is arranged at a center of the first curved surface of the first gas distribution tube.

7. The slot-die type gas distribution device for photovoltaic manufacturing according to claim 1, wherein the slot-die type gas distribution device further comprises a second gas distribution device, wherein the second gas distribution device is provided with a second inlet and a second outlet.

8. The slot-die type gas distribution device for photovoltaic manufacturing according to claim 7, wherein the second gas distribution device comprises a second gas distribution tube, the second outlet is arranged at a top of the second gas distribution tube, so that a flow direction of gas flowing out of the second outlet is perpendicular to a bottom surface of the second gas distribution tube, a position of the second inlet is lower than that of the second outlet, and the top of the second gas distribution tube is a highest position of the second gas distribution tube from the ground; and the second inlet is arranged along a length direction of the second gas distribution tube and has a length equal to that of the second gas distribution tube.

9. The slot-die type gas distribution device for photovoltaic manufacturing according to claim 8, wherein a height of the second inlet is greater than that of the first outlet.

10. The slot-die type gas distribution device for photovoltaic manufacturing according to claim 9, wherein the second gas distribution tube is semicircular or tetragonal.

11. The slot-die type gas distribution device for photovoltaic manufacturing according to claim 10, wherein when the second gas distribution tube is semicircular and includes a second rectangular plane and a second curved surface, the second rectangular plane of the second gas distribution tube is located beneath the second curved surface of the second gas distribution tube, and the second rectangular plane of the second gas distribution device is parallel to the ground; the second inlet is arranged on the second curved surface of the second gas distribution tube, and a height of the second inlet from the second rectangular plane of the second gas distribution tube is less than a radius of the second gas distribution tube; the second outlet is arranged on the second curved surface of the second gas distribution tube, and a height of the second outlet from the second rectangular plane of the second gas distribution tube is the radius of the second gas distribution tube.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows a schematic diagram of some photovoltaic stacks (top layer+lower stack) reacting with gas under a heating condition in a process chamber;

(2) FIG. 2a) and FIG. 2b) shows a standard design of the existing selenization/sulfurization process box in an embodiment, where FIG. 2a) shows a three-dimensional view, and FIG. 2b) shows a detailed side view;

(3) FIG. 3a) and FIG. 3b) shows a standard design of the left gas inlet portion in an embodiment of the existing selenization/sulfurization process device, where FIG. 3a) shows a top view, and FIG. 3b) shows a side view;

(4) FIG. 4a) and FIG. 4b) shows a schematic diagram of nonuniform gas distribution in an embodiment of a standard selenization/sulfurization process box, where FIG. 4a) shows simulated gas streamlines in the selenization/sulfurization process box, and FIG. 4b) shows an optically scanned picture of the top layer of a related photovoltaic stack processed in the standard selenization/sulfurization process box under the same process conditions;

(5) FIG. 5a), FIG. 5b) and FIG. 5c) shows different existing designs of the gas inlet section of the process chamber: FIG. 5a) standard design; FIG. 5b) modified design 1; and FIG. 5c) modified design 2;

(6) FIG. 6a) and FIG. 6b) shows nonuniform gas distribution in two improved process boxes: FIG. 6a) simulated gas streamlines of improved design 1 (FIG. 5b); and FIG. 6b) simulated gas streamlines of improved design 2 (FIG. 5c));

(7) FIG. 7 shows a schematic diagram of the connection relationship between a first gas distribution device and a first communication device designed at the gas inlet portion of a process chamber in the present invention;

(8) FIG. 8 shows another schematic diagram of the design of the gas inlet portion of the process chamber in the present invention;

(9) FIG. 9 shows a schematic structural diagram of the first gas distribution device in the present invention;

(10) FIG. 10 shows a schematic diagram of the connection relationship between a second gas distribution device and a third communication device designed at the gas outlet portion of the process chamber in the present invention;

(11) FIG. 11a) and FIG. 11b) is a schematic structural diagram of the gas inlet portion when the first gas distribution device is semicircular in the present invention, where FIG. 11a) shows a top view, and FIG. 11b) shows a side view;

(12) FIG. 12a) and FIG. 12b) is a schematic structural diagram of the gas outlet portion when the second gas distribution device is semicircular in the present invention, where FIG. 12a) shows a top view, and FIG. 12b) shows a side view;

(13) FIG. 13 is the comparison of the gas velocities in X axis between the standard design and a slot-die type design of the present invention in the case of adopting the designs of FIGS. 11a), 11b), 12a) and 12b);

(14) FIG. 14 is the comparison of the gas velocities in Y axis between the standard design and the slot-die type design of the present invention in the case of adopting the designs of FIGS. 11a), 11b), 12a) and 12b);

(15) FIG. 15 is the comparison of the gas velocities in Z axis between the standard design and the slot-die type design of the present invention in the case of adopting the designs of FIGS. 11a), 11b), 12a) and 12b);

(16) FIG. 16 is a schematic diagram of simulated gas streamlines in the process chamber in the case of adopting the designs of FIGS. 11a), 11b), 12a) and 12b);

(17) FIG. 17a) and FIG. 17b) is a schematic diagram of first gas distribution tubes at the gas inlet portion according to a further embodiment adopting two tetragonal designs with the same size, where FIG. 17a) shows a top view, and FIG. 17b) shows a side view;

(18) FIG. 18a) and FIG. 18b) is a schematic diagram of first gas distribution tubes at the gas inlet portion according to a further embodiment adopting two tetragonal designs with different sizes, where FIG. 18a) shows a top view, and FIG. 18b) shows a side view;

(19) FIG. 19 is a comparison of the gas velocity in X axis in the semicircular design and in two tetragonal designs adopted by the first gas distribution device;

(20) FIG. 20a) and FIG. 20b) is a schematic diagram of a second gas distribution device at the gas outlet portion according to a further embodiment adopting a tetragonal design, where FIG. 20a) shows a top view, and FIG. 20b) shows a side view;

(21) FIG. 21a) and FIG. 21b) is a schematic diagram of the second gas distribution device at the gas outlet portion according to a further embodiment adopting a tetragonal design with a smaller size, where FIG. 21a) shows a top view, and FIG. 21b) shows a side view.

DESCRIPTION OF EMBODIMENTS

(22) In the present invention, a slot-die type first gas distribution device and a first communication device are designed on the gas inlet portion at a process box inlet, a slot-die type second gas distribution device and a third communication device are designed on the gas outlet portion at a process chamber outlet, and thereby, the problem of nonuniform gas distribution in a photovoltaic manufacturing process box is solved.

Embodiment 1

(23) Referring to FIG. 7, for the gas inlet portion at the process box inlet, the first gas distribution device adopting the slot-die design is designed to replace a manifold 3 used in a standard design. In the present embodiment, the first gas distribution device 105 and the first communication device 9 are adopted to distribute and transmit gas into a process chamber 20. The first communication device 9 is a flat quadrangular hollow box (interconnection slit), with two opposite sides of the hollow box being uncovered and used as an inlet and an outlet respectively, and the shapes and sizes of a first outlet, a first communication device inlet, a first communication device outlet and a process chamber inlet are the same. With regard to the hollow box, the length is greater than the width, the width is greater than the height, and the two uncovered sides of the hollow box are parallel to the height direction of the hollow box, that is, a hollow box inlet is long and narrow.

(24) Referring to FIG. 8, at the gas inlet portion of the process box, the gas passes through a gas inlet tube inlet 1, a gas inlet tube 2, a gas inlet tube outlet, a first gas distribution device inlet (i.e. a first inlet) 101, the first gas distribution device 105, a first gas distribution device outlet (i.e. the first outlet) 102, a first communication device inlet (i.e. the hollow box inlet) 103, the first communication device 9, a first communication device outlet (i.e. a hollow box outlet, i.e. gas orifice) 5 and the process chamber inlet 104 in sequence, and is then transmitted into a process chamber 20.

(25) The first communication device inlet is rectangular, and the length and width of the first communication device inlet are the length and height of the first communication device (flat quadrangular hollow box). The shapes and sizes of the first outlet 102, the first communication device inlet 103, the first communication device outlet 5 and the process chamber inlet 104 are the same. Further, after the gas is transmitted out from the first outlet 102 of the first gas distribution device 105, the size and shape of the gas flow section always remain the same in the process of flowing through the first communication device inlet 103, the first communication device 9, the first communication device outlet 5 and the process chamber inlet 104.

(26) Preferably, the ratio of the length, width and height of the flat quadrangular hollow box is between 5000:20:1 and 20000:100:1, that is, the ratio of the lengths and widths of the first outlet, the first communication device inlet, the first communication device outlet and the process chamber inlet is between 5000:1 and 20000:1.

(27) Further, the first gas distribution device 105 includes a first gas distribution tube 1051, and the first inlet is arranged at the top of the first gas distribution tube. Preferably, the first inlet is arranged at the center of the top of the first gas distribution tube, and the position of the first outlet is lower than that of the first inlet. It can be understood that the shape and size of the first inlet depend on those of the gas inlet tube 2, and the first outlet is long and narrow.

(28) Further, referring to FIG. 9, the first gas distribution device 105 may include a plurality of first gas distribution tubes 1051, for example, m first gas distribution tubes 1051 are communicated in sequence to form a first gas distribution device 105. For convenience, the m first gas distribution tubes are also communicated with one another by using the aforementioned first communication device, and here, the first communication device 9 used between the m first gas distribution tubes is referred to as a second communication device 7. It can be understood that the second communication device 7 and the first communication device 9 are actually the same device, and first and second here are only intended to distinguish the different installation positions of the communication device.

(29) Further, the aforementioned m is equal to 2, so that a uniform gas distribution process can be implemented multiple times, increasing the uniformity of the gas entering the process chamber. For example, in FIG. 9, the first inlet is arranged at the center of the top of the first gas distribution tube 1051, the first outlet is arranged at a position below the top on the last first gas distribution tube, and thereby, the gas enters from the top of the first gas distribution tube 1051. The uniform gas distribution process is carried out in the first gas distribution tube 1051 for the first time, the gas is then transmitted into the last first gas distribution tube 1051 through the second communication device 7 to undergo the uniform gas distribution process for the second time, and the gas is then transmitted to the process chamber 20 through the first communication device 9. Therefore, in the gas inlet portion at the process box inlet, before entering the process chamber, the gas enters the first gas distribution device 105 from the gas inlet tube 2, and undergoes the uniform gas distribution process at least twice in the first gas distribution device 105, and the area, shape and height of the flow section of the gas flow always remain the same when the gas is transmitted through the second communication device 7, the first outlet 102, the first communication device 9 and the process chamber inlet 104, thus effectively ensuring the uniformity of distribution of the gas entering the process chamber.

(30) Further, referring to FIG. 10, the present invention designs a second gas distribution device adopting the slot-die design for the gas outlet portion at a process box outlet. The design of the second gas distribution device 13 is similar to that of the first gas distribution device 105. Specifically, the second gas distribution device 13 is provided with a second inlet 106 and a second outlet 107, a process chamber outlet 11 is connected to the second inlet 106, and the second outlet 107 is connected to a gas outlet tube 14.

(31) The process chamber outlet 11 and the second inlet 106 (the second gas distribution device 13) are communicated with each other through a third communication device 12, which has the same structure as the first communication device 9. It can be understood that the third communication device 12 is actually the same as the first communication device 9 and the second communication device 7, and third, first and second here are only intended to distinguish the different installation positions of the communication device. After a photovoltaic device is processed in the process chamber, the gas flows out from the process chamber outlet 11, and flows into the second gas distribution device 13 through the third communication device 12. Referring to the above description of the gas inlet portion of the process chamber, at the gas outlet portion of the process chamber, the process chamber outlet 11, the inlet of the third communication device 12, the outlet of the third communication device 12 and the second inlet 106 are all long and narrow, with the shapes and sizes being the same as those of the uncovered sides of the hollow box as the third communication device 12. That is, the lengths of the process chamber outlet 11, the inlet of the third communication device 12, the outlet of the third communication device 12 and the second inlet 106 are equal to that of the third communication device 12, and the widths of the process chamber outlet 11, the inlet of the third communication device 12, the outlet of the third communication device 12 and the second inlet 106 are equal to the height of the third communication device 12. The area and shape of the gas flow section of the gas flowing out of the process chamber outlet 11 remain the same in the whole process of flowing.

(32) The second gas distribution device 13 includes a second gas distribution tube, the second outlet is arranged at the top of the second gas distribution tube (preferably, at the center of the top of the second gas distribution tube), and the position of the second inlet is lower than that of the second outlet. The second inlet is arranged along the length direction of the second gas distribution tube, and the length of the second inlet is equal to that of the second gas distribution tube. It can be known from the above that the lengths of the process chamber outlet 11, the third communication device 12 and the second gas distribution device 13 are equal.

(33) Because there is no need to redistribute the gas for multiple times, only one second gas distribution tube is used for gas collection in the second gas distribution device 13, and the gas in the second gas distribution tube passes through the gas outlet tube 14 after being uniformly distributed, and finally leaves a gas outlet tube outlet 15.

(34) It should be noted that the height of the second inlet of the process chamber outlet portion is greater than that of the first outlet of the process chamber inlet portion, that is, the height of the process chamber outlet is greater than that of the process chamber inlet.

Embodiment 2

(35) In the present embodiment, the first gas distribution tube 1051 is semicircular. Referring to FIG. 11a) and FIG. 11b), FIG. 11a) shows a top view, and FIG. 11b) shows a side view. The arrows indicate the movement of the gas flow. In order to avoid unnecessary repetition, only the differences with respect to the first gas distribution device in the aforementioned embodiment will be explained.

(36) In the present embodiment, the first gas distribution device includes two semicircular manifolds, i.e. half cylindrical first gas distribution pipeline 6 and first gas distribution pipeline 8, with the rectangular plane of the semicircular manifold being located beneath the curved surface of the semicircular manifold and parallel to the ground.

(37) The first inlet 101 is arranged on the curved surface of the first semicircular manifold 6 (preferably, at the center of the curved surface), and the height of the first inlet 101 from the rectangular plane of the semicircular manifold is the radius of the semicircular manifold.

(38) The two semicircular manifolds are connected with each other through the second communication device 7, the first outlet 102 is arranged on the curved surface of the second semicircular manifold 8, and the height of the first outlet 102 is less than that of the first inlet 101. When there are a plurality of first gas distribution tubes in the first gas distribution device, each first gas distribution tube is further provided with a gas flow orifice 1052 for communicating the first gas distribution tube (6, 8) with the second communication device 7.

(39) The first outlet is arranged along the length direction of the semicircular manifold 8, the distance between the two semi-circular planes of the semicircular manifold 8 is the length of the semicircular manifold 8, and the length of the first outlet 102 is equal to that of the semicircular manifold 8. Thus, the gas is uniformly distributed for the first time in the first semicircular manifold 6, transmitted to the second semicircular manifold 8 through the second communication device 7, uniformly distributed for the second time in the second semicircular manifold 8 and transmitted to the process chamber 20 through the first communication device 9, and the height, area and shape of the gas flow section at each inlet/outlet remain the same before the gas enters the process chamber.

(40) Since the two semicircular manifolds (6, 8) are used to carry out the uniform gas distribution process twice, the uniformity of distribution of the gas in the first gas distribution tube along the Z axis is greatly increased. In order to realize the laminar gas flow in the second communication device 7 and the first communication device 9, and the ratio of the lengths, widths and heights of the second communication device 7 and the first communication device 9 is between 5000:20:1 and 20000:100:1.

(41) In the present embodiment, the second gas distribution tube is semicircular. Referring to FIG. 12a) and FIG. 12b), FIG. 12a) shows a top view, and FIG. 12b) shows a side view. The arrows indicate the movement of the gas flow. In order to avoid unnecessary repetition, only the differences with respect to the second gas distribution device in the aforementioned embodiment will be explained.

(42) In the present embodiment, the second gas distribution device includes a semicircular second gas distribution manifold, the rectangular plane of the semicircular manifold of the second gas distribution tube is located beneath the curved surface of the semicircular manifold, and the rectangular plane of the semicircular manifold of the second gas distribution device is parallel to the ground.

(43) The second inlet 106 is arranged on the curved surface of the semicircular manifold, and the height of the second inlet from the rectangular plane of the semicircular manifold is less than the radius of the semicircular manifold.

(44) The second outlet 107 is arranged at the center of the curved surface of the semicircular manifold, and the height of the second outlet from the rectangular plane of the semicircular manifold is the radius of the semicircular manifold.

(45) In order to evaluate the influence of the design of the gas inlet portion and gas outlet portion of the process box of the present embodiment on the gas uniformity in the process chamber, the same hydrodynamic simulation as in FIG. 4a), FIG. 4b), FIG. 6a) and FIG. 6b) was carried out. For simulation settings, the top and other boundaries of the process box are arranged as normal walls, that is, there is no gas outlet. The gas is jetted out from the left inlet and leaves from the right outlet. The other boundary conditions remain the same as in FIG. 4a), FIG. 4b), FIG. 6a) and FIG. 6b).

(46) FIGS. 13, 14, 15 and 16 describe the related simulation results of gas velocities in X, Y and Z axis and gas streamline distributions, respectively.

(47) FIG. 13 shows the comparison between gas velocities in X axis in the standard design (FIG. 4a) and FIG. 4b)) and in the slot-die type gas distribution device design (FIG. 11a), FIG. 11b), FIG. 12a) and FIG. 12b)) in the embodiments of the present invention. In FIG. 13, for the standard design, the circled lines should represent the gas velocity distribution, where each circle represents the gas outlet velocity at the outlet 5. For the slot-die design, the gas velocity in FIG. 13 is a continuous solid line, because a square-edged outlet 5 is applied. It can be clearly seen that with the help of the slot-die design, the velocity distribution of the related gas in X axis is more uniform than that in the standard design. The variation between the maximum and minimum gas velocities between the twenty outlets 5 in the standard design is about 1 m/s. For the slot-die type gas distribution device design in the embodiments of the present invention, the gas velocity change is about 0.1 m/s, that is, the distribution of the gas ejection in X axis is much more uniformly distributed along the Z axis than that in the standard design.

(48) FIGS. 14 and 15 show the comparison between gas velocities in Y axis and Z axis in the standard design and the slot-die type gas distribution device design of the embodiments of the present invention respectively. Obviously, for the standard design, the gas velocity variation in Y axis and Z axis is about 0.1 m/s, while the gas velocity variation in the slot-die design is negligible.

(49) FIG. 16 shows the gas distribution streamlines in the process chamber adopting the slot-die design according to the embodiments of the present invention. It clearly indicates that neither finger-shaped gas jets nor gas vortexes can be observed here. The gas streamlines are parallel to one another, and the flow of the gas is more uniformly distributed in the whole process chamber.

Embodiment 3

(50) In order to avoid unnecessary repetition, only the differences with respect to the aforementioned embodiment will be explained. Referring to FIG. 17a) and FIG. 17b), FIG. 17a) shows a top view, and FIG. 17b) shows a side view. The arrows indicate the movement of the gas flow. In the present embodiment, the first gas distribution tubes 1051 in the first gas distribution device are manifolds with rectangular configuration, and the two first gas distribution tubes 1051 have the same size. Since the two first gas distribution tubes 1051 are used to implement the uniform gas distribution process twice, similar uniform gas distribution can be realized in the process chamber 20.

Embodiment 4

(51) In order to avoid unnecessary repetition, only the differences with respect to the aforementioned embodiment will be explained. Referring to FIG. 18a) and FIG. 18b), FIG. 18a) shows a top view, and FIG. 18b) shows a side view. The arrows indicate the movement of the gas flow. In the present embodiment, the first gas distribution tubes 1051 in the first gas distribution device are manifolds with rectangular configuration, and the two first gas distribution tubes 1051 have different sizes. Since the first gas distribution tube 1051 is larger than the size shown in FIG. 17a) and FIG. 17b), the gas flow distribution at the outlet 5 along Z axis can be slightly improved in comparison with the design of FIG. 17a) and FIG. 17b).

(52) FIG. 19 shows the comparison between gas velocities in X axis in the aforementioned two designs of FIG. 17a), FIG. 17b), FIG. 18a) and FIG. 18b), and the gas distribution effects of these two designs are also compared with that of the semicircular design shown in FIG. 13. It can be seen that similar to the semicircular design, the gas flow velocity output by the larger tetragonal first gas distribution tube 1051 is more uniform than that output by the smaller tetragonal first gas distribution tube 1051.

Embodiment 5

(53) In order to avoid unnecessary repetition, only the differences with respect to the aforementioned embodiment will be explained. Referring to FIG. 20a) and FIG. 20b), FIG. 20a) shows a top view, and FIG. 20b) shows a side view. The arrows indicate the movement of the gas flow. In the embodiments of the present invention, another embodiment is provided for the design of the gas outlet portion of the process chamber. In the gas outlet portion of the process chamber, the second gas distribution tube of the second gas distribution device adopts a manifold tetragonal design.

Embodiment 6

(54) In order to avoid unnecessary repetition, only the differences with respect to the aforementioned embodiment will be explained. Referring to FIG. 21a) and FIG. 21b), FIG. 21a) shows a top view, and FIG. 21b) shows a side view. The arrows indicate the movement of the gas flow. In the embodiments of the present invention, in the gas outlet portion of the process chamber, the second gas distribution tube of the second gas distribution device adopts a manifold with tetragonal design, and the size of the tetragonal second gas distribution tube is smaller than that in Embodiment 5.

(55) In a word, the present invention provides a slot-die type gas distribution device for photovoltaic manufacturing, and provides slot-die type gas distribution structure designs at the gas inlet portion and the gas outlet portion, respectively. Compared with the standard design using the manifold with a plurality of outlet tubes, the present invention realizes more uniform gas distribution in the process box by setting each inlet/outlet in the gas flow process into a long and narrow shape, effectively improving the semiconductor performance and appearance of photovoltaic products.

(56) The present invention is not limited to the aforementioned specific embodiments, and various changes which are made by those of ordinary skill in the art from the above idea without creative labor shall fall within the protection scope of the present invention.

LIST OF REFERENCE CHARACTERS

(57) 1 gas inlet tube inlet 2 gas inlet tube 3 gas manifold 4 transfer tube 5 hollow box outlet 6, 8, 1051 first gas distribution tube 7 second communication device 9 first communication device 10 bowl-shaped hole 11 process chamber outlet 12 third communication device 13 second gas distribution device 14 gas outlet tube 15 gas outlet tube outlet 16 process box 17 bottom plate 18 substrate 19 cover plate 20 process chamber 101 first inlet 102 first outlet 103 hollow box inlet 104 process chamber inlet 105 first gas distribution device 106 second inlet 107 second outlet 1052 gas flow orifice