A semiconductor processing apparatus

Abstract

A dual-chamber fractal (DPF) spray head is provided for distributing different semiconductor processing gases across the entire semiconductor wafer during processing operations. The DPF spray head can have multiple layers, each with a pattern of gas distribution characteristics. The shape of the gas distribution characteristics on each layer is approximately similar to the shape of the gas distribution characteristics on its immediately adjacent upstream layer, but smaller in size. This fractal structure of the gas flow channels provides a very uniform delivery of processing gases across the entire semiconductor wafer surface during processing operations, thereby improving wafer uniformity.

Description

[Technical Field]

[0001] This invention relates to a dual-inflatable-chamber fractal spray head. [Previous Technology]

[0002] Semiconductor manufacturing tools often include "spray heads" for distributing semiconductor processing gases in a distributed manner on a semiconductor wafer being processed. These spray heads are typically characterized by a large open gas chamber space, for example, a cylindrical volume designed with a diameter at least the same as the diameter of the wafer being processed, which is then fluidly connected to a plurality of gas distribution ports on the underside of the spray head. In some of these tools, the spray head can be configured to distribute two different types of processing gases on the wafer being processed.

[0003] This article discloses a novel dual-gas spray head design for use in semiconductor processing tools. [Summary of the Invention]

[0004] Details of one or more embodiments of the subject matter described in this specification are set forth in the accompanying drawings and the following description. Other features, features, and advantages will become apparent from the description, drawings, and claims.

[0005] In some embodiments, a semiconductor processing apparatus including a spray head is provided. The spray head may include a body, a first gas chamber inlet, a second gas chamber inlet, a plurality of first gas distribution holes, and a plurality of second gas distribution holes. The body may also include a plurality of layers, the plurality of layers including suitable subsets of two or more fractal layers, each fractal layer including a set of first radially symmetric gas distribution features and a set of second radially symmetric gas distribution features. Each first radially symmetric gas distribution feature may include a first central gas chamber, a plurality of first spoke channels fluidly connected to and radiating outward from the first central gas chamber, and a plurality of first vertical ports, each first vertical port being located at a distal end of one of the first spoke channels. Each second radially symmetric gas distribution feature includes a second central gas chamber, a plurality of second spoke channels fluidly connected to and radiating outward from the second central gas chamber, and a plurality of second vertical ports, each second vertical port being located at a distal end of one of the second spoke channels. For each of the fractal layers, each first radially symmetrical gas distribution feature of the fractal layer can be positioned such that the corresponding first central gas chamber is positioned below a first vertical port of the adjacent upstream layer, and each second radially symmetrical gas distribution feature of the fractal layer can be positioned such that the corresponding second central gas chamber is positioned below a second vertical port of the adjacent upstream layer.

[0006] In some embodiments, one of the fractal layers may also include a set of first partial radially symmetrical gas distribution features, each first partial radially symmetrical gas distribution feature having a first central gas chamber having a smaller number of first spoke channels fluidly connected to it compared to any of the first radially symmetrical gas distribution features of the fractal layer.

[0007] In some further embodiments, the body may further include a feed layer immediately upstream of the fractal layer having the first portion of radially symmetrical gas distribution characteristics. In these embodiments, the feed layer may include a plurality of first feed chambers, each first feed chamber having one or more first feed spoke channels fluidly connected thereto, each first feed spoke channel having a first feed riser port at its distal end, and each first feed riser port being positioned above and fluidly connected to one of the first central chambers in the fractal layer immediately downstream of the feed layer. In these embodiments, the first feed spoke channels having the first feed riser port fluidly connected to the first central chamber in the fractal layer immediately downstream of the feed layer having the first portion of radially symmetrical gas distribution characteristics may each have a first length, and the first feed spoke channels having the first feed riser port fluidly connected to the first central chamber in the fractal layer immediately downstream of the feed layer having the first portion of radially symmetrical gas distribution characteristics may each have a length longer than the first length.

[0008] In some further or alternative embodiments of these embodiments, the fractal layer having the first set of radially symmetrical gas distribution features may also include a set of second radially symmetrical gas distribution features, each of the second radially symmetrical gas distribution features having a second central gas chamber having a smaller number of second spoke channels compared to any of the second radially symmetrical gas distribution features of the fractal layer.

[0009] In some of these embodiments, the body may further include a feed layer immediately upstream of the fractal layer having the first portion of radially symmetrical gas distribution characteristics and the second portion of radially symmetrical gas distribution characteristics. In these embodiments, the feed layer may include a plurality of first feed filling chambers and a plurality of second feed filling chambers, each first feed filling chamber having one or more first feed spoke channels fluidly connected thereto, and each second feed filling chamber having one or more second feed spoke channels fluidly connected thereto, each first feed spoke channel having a first feed riser port at its distal end, and each second feed spoke channel having a second feed riser port at its distal end, each first feed riser port being positioned above and fluidly connected to one of the corresponding first central filling chambers in the fractal layer immediately downstream of the feed layer, and each second feed riser port being positioned above and fluidly connected to one of the corresponding second central filling chambers in the fractal layer immediately downstream of the feed layer. In these embodiments, each of the first feed spoke channels having a first feed vertical port fluidly connected to a first central air chamber having a first radially symmetrical gas distribution characteristic in a fractal layer immediately downstream of the feed layer may have a first length. Each of the first feed spoke channels having a first feed vertical port fluidly connected to a first central air chamber having a first partial radially symmetrical gas distribution characteristic in a fractal layer immediately downstream of the feed layer may have a length longer than the first length. Each of the second feed spoke channels having a second feed vertical port fluidly connected to a second central air chamber having a second radially symmetrical gas distribution characteristic in a fractal layer immediately downstream of the feed layer may have a second length. Each of the second feed spoke channels having a second feed vertical port fluidly connected to a second central air chamber having a second partial radially symmetrical gas distribution characteristic in a fractal layer immediately downstream of the feed layer may have a length longer than the second length.

[0010] In some embodiments, the first radially symmetrical gas distribution feature of the fractal layer may each include four first spoke channels, and the second radially symmetrical gas distribution feature of the fractal layer may each include four second spoke channels.

[0011] In some further embodiments of these embodiments, the first spoke channels and the second spoke channels of the first radially symmetric gas distribution feature and the second radially symmetric gas distribution feature of at least one fractal layer may be at the same height.

[0012] In some additional or alternative embodiments of these embodiments, the first spoke channels may each be aligned with one of the two orthogonal first channel axes, the second spoke channels may each be aligned with one of the two orthogonal second channel axes, and the first channel axis may be 45° out of phase with the second channel axis (or at a 45° angle relative to the second channel axis).

[0013] In some further or alternative embodiments, for each of the fractal layers having an adjacent upstream fractal layer, the first radially symmetrical gas distribution feature of the fractal layer may each have a center-to-center spacing between its corresponding first vertical port, which is approximately 50% of the corresponding center-to-center spacing between the first vertical ports in the first radially symmetrical gas distribution feature of the adjacent upstream fractal layer.

[0014] In some further or alternative embodiments, for each of the fractal layers having an adjacent upstream fractal layer, the second radially symmetrical gas distribution feature of the fractal layer may each have a center-to-center spacing between its corresponding second vertical port, which is approximately 50% of the corresponding center-to-center spacing between the second vertical ports in the second radially symmetrical gas distribution feature of the adjacent upstream fractal layer.

[0015] In some embodiments, there may be at least three fractal layers.

[0016] In some embodiments, the body may be made of ceramic material.

[0017] In some further embodiments of these embodiments, the body may be made of multiple discrete layers of ceramic material fused together.

[0018] In some further or alternative embodiments of these embodiments, the body may be a 3D printed structure.

[0019] In some embodiments, the device may further include a processing chamber and a base. In these embodiments, the base may be positioned within the processing chamber, and the spray head may be positioned above the base within the processing chamber.

Implementation Method

[0035] Importantly, the concepts discussed herein are not limited to any single variant or implementation discussed herein, nor are they limited to any combination and / or arrangement of such variants and / or implementations. Furthermore, each variant and / or implementation of the present invention may be used alone, or in combination with one or more of other variants and / or implementations. For the sake of brevity, many of these arrangements and combinations will not be discussed and / or described separately herein.

[0036] The dual-chamber fractal nozzle discussed herein can be configured to uniformly distribute process gas to a processing volume located above a semiconductor wafer within a semiconductor processing chamber. Compared to more conventional dual-chamber spray nozzles, these dual-chamber fractal (DPF) spray nozzles offer numerous advantages. For example, since there is no large gas chamber, such as a roughly circular gas chamber spanning the entire area where the gas distribution port of the spray nozzle is located, the amount of process gas that must be introduced into the spray nozzle to be delivered through the gas distribution port of the spray nozzle can be significantly reduced in the DPF spray nozzle design discussed herein compared to conventional open-chamber volume spray nozzles. Another benefit is that, for a given filling chamber of a DPF spray head, the fractal characteristics of the numerous flow paths within the DPF spray head ensure that the flow paths leading to each gas distribution port have equal or at least very similar flow resistance, thus reducing or eliminating the variability in the time it takes for gas introduced into the filling chamber through the inlet to reach any given gas distribution port within that filling chamber. For example, gas flowing through the filling chamber of a fractal spray head, regardless of which gas distribution port it ultimately flows to, may generally experience substantially the same fluid path characteristics. For instance, after the gas reaches the fractal layers of such spray heads (which will be described in detail later), the gas may flow through continuous airflow channels with similar channel segments of similar length, cross-sectional shape, and area. This can help facilitate more uniform wafer processing because the entire wafer surface will be exposed to these process gases substantially simultaneously, unlike a spray head where, for example, the process gases flow from the center of the spray head for a period of time before flowing out of the periphery of the spray head. Another advantage of the DPF nozzles discussed in this article is that they can be made of a variety of materials, including metals (stainless steel, aluminum, etc.) and ceramics (alumina, silicon oxide, etc.).

[0037] Generally, a DPF spray head (such as those discussed herein) may have two patterns of gas distribution holes on the underside of the spray head, one for each gas chamber. In the DPF example discussed below, the two patterns are generally square patterns, which are 45° out of phase with each other (and several examples of gas distribution holes at the corners of each square pattern are omitted, for example, a 4x4 sub-pattern of gas distribution holes is omitted at each corner of each pattern). The 45° out of phase can be arranged for the internal layout of a number of channels that partially define the two gas distribution chambers within the exemplary DPF spray head. This allows for a very dense encapsulation of airflow channels within the DPF spray head and a reduced pitch of the gas distribution holes, thus allowing for a finer distribution of process gases across the entire semiconductor wafer.

[0038] The DPF spray head can be used for both asynchronous (i.e., process gases alternately flowing through each filling chamber at different times) and synchronous (i.e., process gases simultaneously flowing through two filling chambers). In some additional instances, the DPF spray head can be used in a mixed configuration, where one filling chamber has a continuously flowing process gas, while another filling chamber has two or more different gases flowing through it alternately or in a cyclic manner. In the former example, it can be applied, for example, to atomic layer deposition or other processes with alternating process gas application. Compared to conventional spray heads, the reduced volume of the DPF spray head allows for a reduction in delay time before the desired amount of process gas is delivered to the wafer, thus reducing the total duration of each gas injection cycle (and thereby reducing processing time / increasing yield). In the latter example, it can be applied, for example, to processing operations where two process gases simultaneously flow into the processing space above a semiconductor wafer to react and achieve the desired processing effect on the wafer. Improving the simultaneity performance of the DPF spray head reduces the chance that one reactant is present in the wafer processing space while the other is not. In particular, the DPF spray head discussed herein can be used in, for example, the methods discussed in U.S. Patent Application No. 62 / 767,198 (filed November 14, 2018, entitled “METHODS FOR MAKING HARD MASKS USEFUL IN NEXT-GENERATION LITHOGRAPHY”) and U.S. Patent Application No. 62 / 868,710 (filed June 28, 2019, entitled “EUV PHOTORESIST WITH MULTIPLE EUV-ABSORBING ELEMENTS AND VERTICAL COMPOSITION GRADIENT”), both of which are incorporated herein by reference in their entirety.

[0039] Figure 1 shows an isometric view of an exemplary dual-chamber fractal (DPF) spray head; Figure 2 shows a reverse isometric view of the exemplary DPF spray head of Figure 1. Figures 3 and 4 show top and bottom views of the same exemplary DPF spray head of Figure 1.

[0040] In appearance, the DPF spray head 100 of Figure 1 differs slightly from many other dual-chamber spray heads—it is generally circular in shape, with a plurality of air inlets on its top surface, such as a first air chamber inlet 102 and a plurality (four) second air chamber inlets 104 in this example, and two hole patterns on its bottom surface, such as the first hole pattern 112 and the second hole pattern 114 of gas distribution holes (e.g., the first gas distribution hole 106 and the second gas distribution hole 108). It will be noted that both the first hole pattern 112 and the second hole pattern 114 are in the form of a generally rectangular (or more precisely, a square) array, but the two rectangular arrays are oriented at 45° different phases from each other. There is also an additional first gas distribution hole 106, which is not part of the rectangular first hole pattern 112—this additional first gas distribution hole 106 is located at the center of the DPF spray head 100. In most conventional spray heads, the orifice pattern of the gas distribution holes is typically limited to an outer region having a generally circular shape; that is, the orifice pattern extends outward to a circular boundary, and all gas distribution holes for a given filling chamber are located within this circular boundary and are distributed substantially uniformly within it. However, this is not the case in the exemplary DPF spray head (but it may be, as discussed further below). It can be seen that the first gas distribution hole 106 and the second gas distribution hole 108 are distributed substantially uniformly within the circular wafer overlap region 110 (in this example, the wafer overlap region 110 is designed to be the same size as the semiconductor processing wafer (which is typically positioned below the DPF spray head during processing), for example, a diameter of 300 mm (but in some embodiments, this uniform hole distribution may, for example, be maintained over a circular region of an entire or even larger diameter, for example, to provide uniform gas distribution to or beyond the wafer periphery during processing). However, both the first hole pattern 112 and the second hole pattern 114 have portions extending beyond the wafer overlap region 110. The first gas distribution port 106 and the second gas distribution port 108 outside region 110 are no longer uniformly distributed relative to each other. As will be seen in the following discussion, the exemplary DPF spray head includes gas distribution ports located outside the wafer overlap region 110 to allow the numerous gas distribution features for each gas chamber in the many layers within the DPF spray head to have the same design for each layer; it will be understood that, with appropriate modifications (e.g., by using gas distribution features of varying designs near the periphery of the DPF spray head 100 in these layers), a DPF spray head with reduced or eliminated gas distribution ports outside the wafer overlap region 110 can be provided. These alternative embodiments are also considered to be within the scope of the invention.

[0041] It will be observed that, in the exemplary embodiment, the array spacing d1 and d2 of the first hole pattern 112 and the second hole pattern 114 are respectively related, resulting in d1 being approximately 40% larger than d2; other embodiments may have different hole spacing relationships. It is also evident that, due to this spacing, in areas where the two hole patterns substantially overlap, such as within the wafer overlap region 110, the number of second gas distribution holes 108 is twice that of first gas distribution holes 106. For example, if any smallest square region entirely within the wafer overlap region 110 is taken, which includes at least four locations of first gas distribution holes 106 and at least four locations of second gas distribution holes 108 (which include at least one complete pattern repeat along each axis of each pattern), then there will be four instances of half of the second gas distribution holes 108 and four instances of one-quarter of the first gas distribution holes 106 located within this square region, so the ratio of second gas distribution holes 108 to first gas distribution holes 106 is 2:1 (different ratios, such as 1:1, may be seen in other embodiments). In this exemplary DPF spray head, the first gas distribution orifice 106 and the second gas distribution orifice 108 have the same diameter, resulting in the amount of process gas flowing through the second gas distribution orifice 108 being approximately twice that flowing through the first gas distribution orifice 106 when the process gas is directed to its respective inlet and maintained at the same inlet pressure (assuming both filling chambers have subsonic flow conditions; in some practical implementations, a control system with a mass flow controller may be used to ensure that the same mass flow rate of gas is delivered through each filling chamber, which may result in each filling chamber experiencing different inlet pressures and different exit velocities leaving its corresponding gas distribution port). However, in other embodiments, the diameter of one or both of the first gas distribution orifice 106 and the second gas distribution orifice 108 may be varied such that the first gas distribution orifice 106 is larger or smaller than the second gas distribution orifice, to adjust the potential flow rate of the gas flowing through the two sets of gas distribution orifices.

[0042] Figure 5 shows an isometric exploded view of the exemplary DPF spray head of Figure 1. As can be seen from this exploded view, the DPF spray head 100 can be divided into a plurality of different layers 116, each layer having different gas distribution characteristics. It will be understood that such DPF spray heads 100 can be formed, for example, by forming each layer as a discrete component through machining or other means, and then joining or fusing the multiple layers together to form a stack to provide the DPF spray head. However, in other embodiments, other techniques or equivalent structures can be used, for example, additive manufacturing can be used to “3D print” the DPF spray head structure, for example, from metal, ceramic, or other materials.

[0043] In this discussion, a layer referred to as "upstream" of a specific layer will be understood as one that is closer to the "top" of the DPF spray head 100 (e.g., closer to the first inflation chamber inlet 102 or the second inflation chamber inlet 104); a layer referred to as "downstream" of a specific layer will be understood as one that is closer to the "bottom" of the DPF spray head 100 (e.g., closer to the first gas distribution orifice 106 or the second gas distribution orifice 108). A layer referred to as "immediately upstream" of a specific layer refers to the upstream layer closest to that layer. Similarly, a layer referred to as "immediately downstream" of a specific layer refers to the downstream layer closest to that layer. It will also be understood that, although people may arbitrarily divide any given spray head into layers in any manner they deem appropriate, the use of “layer” in this application should be understood to mean, for example, the layer depicted in Figure 5, wherein each layer has a vertical pipe hole (or gas distribution hole) on one side and a gas flow channel / inflation chamber on the other side, and each vertical pipe hole / gas distribution hole in the layer terminates in one of the gas flow channels (the inlet layer may be an exception, which in the form of the first inflation chamber inlet 102 and the second inflation chamber inlet 104 has only a vertical pipe hole passing through it).

[0044] The plurality of layers 116 may include, for example, an inlet layer 118 (including layer 116a), a feed layer 120 (e.g., including layers 116b and 116c), and a fractal layer 122 (e.g., including layers 116d, 116e, and 116f). The inlet layer 118 may include, for example, through holes or other features through which process gases may be introduced into the inflation chamber of the DPF spray head 100, such as a first inflation chamber inlet 102 and a second inflation chamber inlet 104.

[0045] The feed layer 120 may include, for example, a layer 116b, which includes a first feed channel 124 and a second feed channel 126, each of which is fluidly connected within the layer 116b to a first inflation chamber inlet 102 or one of the second inflation chamber inlets 104 and a corresponding first feed riser port 138 or second feed riser port 140. The first feed riser port 138 and the second feed riser port 140 in the layer 116b may pass through the bottom of the layer 116b and are respectively fluidly connected to one of the first feed channel 124 or the second feed channel 126 and a corresponding first feed inflation chamber 130 or second feed inflation chamber 132 in the layer 116c.

[0046] Layer 116c (which is one of the feed layers 120) may have a plurality of gas distribution features, each of which typically takes the form of a central air chamber having a plurality of feed spoke channels extending outward therefrom. For example, layer 116c may have a plurality of first feed air chambers 130 (four shown, but other numbers may also be used—typically as many as the first feed riser port 138 in the adjacent upstream layer 116). Similarly, layer 116c may also have a plurality of second feed air chambers 132 (four shown, but other numbers may also be used—typically as many as the second feed riser port 140 in the adjacent upstream layer 116).

[0047] Each first feed air chamber 130 may have a plurality of first feed spoke channels 134 radiating outward from the first feed air chamber 130; each first feed spoke channel 134 may terminate at a corresponding first feed riser port 138 in layer 116c, the first feed riser port 138 being directed to an adjacent downstream layer 116, such as layer 116d. Similarly, each second feed air chamber 132 may have a plurality of second feed spoke channels 136 radiating outward from the second feed air chamber 132; each second feed spoke channel 136 may terminate at a corresponding second feed riser port 140 in layer 116c, the second feed riser port 140 being directed to an adjacent downstream layer 116. Each of the first feed vertical port 138 and the second feed vertical port 140 in layer 116c can be positioned approximately centered above the corresponding inflation chamber feature in the downstream layer.

[0048] It should be noted that, due to the geometric variations in the feed spoke channels, the feed spoke channels radiating outward from each feed inflation chamber do not necessarily have equal flow resistance. This will be discussed in more detail later.

[0049] It will also be noted that the feed channel and feed spoke channel shown in FIG. 5 each include two internal support walls 128, which typically extend along the length of these channels from one end of the channels to the other. These support walls 128 (or, for example, other structures) may be included as appropriate in some embodiments. For example, if the DPF spray head 100 is made of green-processed ceramic layers (which are stacked together and then fired in a kiln to form a single molten-hardened ceramic component), it may be desirable for wider channels to include one or more internal support walls 128 (or other support structures) to provide mechanical support to the layers forming the “top” of these channels. Other geometries and / or other manufacturing techniques may not require these support walls 128.

[0050] After flowing through the feed layer 120, the process gas is then guided into the fractal layer 122. Each fractal layer 122 is typically characterized by the same repeating radially symmetrical gas distribution feature (or a portion thereof) for each filling chamber, with the radially symmetrical gas distribution feature of each immediately downstream layer being a scaled-down version of the corresponding radially symmetrical gas distribution feature in that layer. In this example, the total size of each radially symmetrical gas distribution feature in the layer is scaled down by approximately 50% from the corresponding radially symmetrical gas distribution feature in the immediately upstream layer, but other embodiments may utilize different scaling ratios. Figure 8 illustrates a size comparison between the groups of radially symmetrical gas distribution features of each of the three fractal layers 122 shown in Figure 5—each group of radially symmetrical gas distribution features is shown proportionally relative to the other groups of radially symmetrical gas distribution features shown. As can be seen from the dashed-dot-dashed line passing through the center of the selected vertical port of each radially symmetric gas distribution feature group, in each fractal layer 122, the center-to-center vertical port spacing of each radially symmetric gas distribution feature group is reduced by 50% compared to the adjacent upstream radially symmetric gas distribution feature group.

[0051] This characteristic gives the gas distribution channels in each inflation chamber of the DPF spray head a "fractal" appearance, thus justifying the name "dual inflation chamber fractal spray head". It will be noted that in some embodiments, a particular sub-feature in each radially symmetrical gas distribution feature may be scaled up or down from the corresponding feature of the radially symmetrical gas distribution feature in the immediately upstream layer. For example, in the exemplary DPF spray head 100, the center-to-center distance between the riser ports of a given radially symmetrical gas distribution feature is 50% of the corresponding center-to-center distance between the riser ports of the immediately upstream radially symmetrical gas distribution feature of that given radially symmetrical gas distribution feature. However, the cross-sectional width of each spoke channel may actually be increased relative to the center-to-center spacing in the immediately upstream radially symmetrical gas distribution feature. Figure 9 provides an additional view of these features. In Figure 9, one of the three sets of first radially symmetrical gas distribution features 146 and four adjacent second radially symmetrical gas distribution features 148 (one set of each of the three fractal layers 122) have been scaled so that their corresponding vertical apertures have the same center-to-center distance, and then stacked so that they are centered on each other. It can be seen that the first and second radially symmetrical gas distribution features 146ʹ and 148ʹ from layer 116e (shown in dotted outlines) have spoke channels that are slightly wider (relative to the center-to-center distance between the vertical apertures) than the corresponding first and second radially symmetrical gas distribution features 146ʹ and 148ʹ. Similarly, the first and second radially symmetrical gas distribution features 146ʹʹ and 148ʹʹ from layer 116f (shown in dashed outlines) have spoke channels that are slightly wider (relative to the center-to-center distance between the vertical apertures) than the corresponding first and second radially symmetrical gas distribution features 146ʹ and 148ʹ.

[0052] In addition, it can be seen that the diameter of the first and second vertical tube holes of each radially symmetric gas distribution feature relative to the center-to-center distance can vary between radially symmetric gas distribution features in the fractal layer (which are adjacent upstream / downstream of each other).

[0053] In some embodiments, a portion of the radially symmetrical gas distribution features of one or more fractal layers 122 may be provided only in a "partial form," that is, only a portion of the radially symmetrical gas distribution features are present. For example, the radially symmetrical gas distribution features in an exemplary DPF spray head are +-shaped or x-shaped, each having four spoke channels radiating outward from the central inflation chamber. A partial radially symmetrical gas distribution feature may be similarly constructed in this case, but without one or two spoke channels.

[0054] For example, in layer 116d, there are a plurality of first radially symmetric gas distribution features 146 and a plurality of second radially symmetric gas distribution features 148, each of which is in a + or × shape (however, it will be noted that the first radially symmetric gas distribution feature 146 is larger than the second radially symmetric gas distribution feature 148—see earlier discussion on array spacing). The first radially symmetric gas distribution feature 146 and the second radially symmetric gas distribution feature 148 each have a corresponding central gas chamber and a plurality of spoke channels radiating outward from it.

[0055] Figure 6 illustrates an exemplary first radially symmetrical gas distribution feature 146, and Figure 7 illustrates an exemplary second radially symmetrical gas distribution feature 148; Figures 6 and 7 are shown to the same scale. It can be seen that the first radially symmetrical gas distribution feature 146 has a first central filling chamber 158, which can be located directly below and fluidly connected to the corresponding first riser port 162 of the upstream layer 116 (or, in some instances, the first feed riser port 138). The first central filling chamber 158 may have a plurality (four in this example) of first spoke channels 154 radiating outwards in a radially symmetrical manner from the first central filling chamber 158. Each first spoke channel 154 may terminate at the corresponding first riser port 162 (or, in the example of the downstream layer 116, at the corresponding first gas distribution hole 106).

[0056] Similarly, the second radially symmetrical gas distribution feature 148 of FIG. 7 has a second central filling chamber 160, which can be located directly below and fluidly connected to the corresponding second riser port 164 of the upstream layer 116 (or, in some instances, the second feed riser port 140). The second central filling chamber 160 may have a plurality (four in this example) of second spoke channels 156 radiating outward from the second central filling chamber 160 in a radially symmetrical manner. Each second spoke channel 156 may terminate at the corresponding second riser port 164 (or, in the example of the downstream layer 116, at the corresponding second gas distribution hole 108).

[0057] Referring back to Figure 5, it will be noted that the first radially symmetric gas distribution feature 146 and the second radially symmetric gas distribution feature 148 generally occupy the central region of layer 116d, but near the periphery of layer 116d, the first partial radially symmetric gas distribution feature 142 and the second partial radially symmetric gas distribution feature 144 are used. Each of the first partial radially symmetric gas distribution features 142 has only two first spoke channels 154, while each of the second partial radially symmetric gas distribution features 144 has only three second spoke channels 156. The remaining fractal layers 122 in this example only have radially symmetric gas distribution features and no partial radially symmetric gas distribution features, but other embodiments may also include partial radially symmetric gas distribution features in other fractal layers 122.

[0058] Although the preceding figures clearly convey the structure of the exemplary DPF spray head 100, Figures 10 to 15 are also provided to show plan views of layers 116a-f of the exemplary dual-chamber fractal spray head of Figure 1. Although these figures are somewhat redundant with the preceding figures, they provide additional clarity and are particularly relevant in the following discussion.

[0059] Unless certain mitigation measures are taken, the use of a partially radially symmetrical gas distribution feature may result in flow imbalance in the DPF spray head, as shown. For example, regarding the corresponding partially radially symmetrical gas distribution feature, if the same amount of process gas is supplied to each central filling chamber of the radially symmetrical gas distribution feature at the same gas flow rate, the vertical ports of the partially radially symmetrical gas distribution feature will each exhibit an increased gas flow rate compared to the vertical ports of the radially symmetrical gas distribution feature—this is because the partially radially symmetrical gas distribution feature has fewer spoke channels and corresponding vertical ports compared to the radially symmetrical gas distribution feature. Therefore, the vertical ports of the partially radially symmetrical gas distribution feature have a smaller total cross-sectional area compared to the vertical ports of the radially symmetrical gas distribution feature, resulting in a larger gas volume flowing through each vertical port of the partially radially symmetrical gas distribution feature. This is undesirable because it will result in a disproportionate amount of gas received by the downstream radially symmetrical gas distribution features in the subsequent layer 116, which are supplied with gas by the partially radially symmetrical gas distribution features (compared to the radially symmetrical gas distribution features in the other identical downstream layers supplied with gas by the radially symmetrical gas distribution features). This, in turn, will ultimately lead to uneven gas delivery through the gas distribution orifice.

[0060] To mitigate or prevent such effects, the feed channel supplying process gas from the feed riser port to the adjacent downstream radially symmetrical gas distribution feature can be designed to have a longer length than the feed channel supplying process gas from the feed riser port to the adjacent downstream radially symmetrical gas distribution feature. For example, in Figure 12, it can be seen that the lengths of two of the three first feed spoke channels 134 radiating outward from each first feed filling chamber 130 are approximately twice the lengths of the remaining first feed spoke channels 134 radiating outward from each first feed filling chamber 130; this increased length increases the flow resistance of these first feed spoke channels 134, resulting in a flow velocity experienced by the first feed riser port 138 located at the end of these first feed spoke channels 134 being approximately half that of the first feed riser port 138 of the remaining first feed spoke channels 134 radiating outward from each first feed filling chamber 130. Similarly, one of the four second feed spoke channels 136 radiating outward from each second feed inflation chamber 132 has an increased length compared to the other second feed spoke channels 136 radiating outward from it; this has a similar effect and can result in a reduced fluid flow rate for the partially radially symmetrical gas distribution characteristics on the immediate downstream layer of only three spokes, thus promoting airflow uniformity outside the DPF spray head 100.

[0061] After the gas reaches each gas distribution feature, before proceeding to the next set of gas distribution features (or outflow gas distribution ports) in the immediately downstream layer, the airflow can be distributed substantially uniformly among the numerous spoke channels; this recursive splitting characteristic can distribute the process gas evenly over the entire large area of ​​the spray head. In this example, there are three fractal layers 122, but more or fewer of these layers can be used depending on how fine or coarse the gas will be distributed.

[0062] In the exemplary DPF spray head 100, it can be seen that for each air chamber, the radially symmetrical gas distribution feature in the given fractal layer 122 has spoke channels aligned with the channel axis, and the channel axes are 45° out of phase with each other. For example, in the fractal layer 116d of FIG5, the first radially symmetrical gas distribution feature 146 has a first spoke channel 154 aligned with the first channel axis 150, and the second radially symmetrical gas distribution feature 148 has a second spoke channel 156 aligned with the second channel axis 152; it can be seen that the first channel axis 150 and the second channel axis 152 are 45° out of phase with each other.

[0063] Figure 16 shows an abstract isometric view of the volume of one air chamber in the exemplary dual-air-chamber fractal spray head of Figure 1. Figure 17 shows an abstract isometric view of the volume of the other air chamber in the exemplary dual-air-chamber fractal spray head of Figure 1. Figure 18 shows an abstract isometric view of the volumes of the two air chambers in the exemplary dual-air-chamber fractal spray head of Figure 1.

[0064] As can be readily seen in Figures 16 to 18, each radially symmetrical gas distribution feature or partially radially symmetrical gas distribution feature in the fractal layer has a central filling chamber, which is fluidly connected to a riser port at the distal end of one of the spoke channels radiating outward from the central filling chamber of the radially symmetrical gas distribution feature in the adjacent upstream fractal layer (or to a feed riser port in one of the feed layers 120). Since the radial spoke channels of each filling chamber in each layer are arranged at 45° different phases, it is possible to achieve a very high gas distribution orifice density on the bottom surface of the DPF spray head, and approximately equal flow resistance can still be achieved from the inlet to any gas distribution port of any filling chamber. For example, such configurations allow each of the plurality of second spoke channels 156 to extend partially into the space between two adjacent first spoke channels 154, thereby allowing each of the associated second riser ports 164 (or second gas distribution holes 108 in layer 116f) to be located at an intermediate position along the line between the two first riser ports 162 (or first gas distribution holes 106) closest to the second riser port.

[0065] It will also be noted that in the exemplary DPF spray head, a number of gas distribution holes and / or radially symmetrical gas distribution features are located outside the wafer overlap region 110. This will provide process gas that may typically never actually reach the wafer, because process gas delivered from the radially symmetrical gas distribution features and / or gas distribution holes within the wafer overlap region 110 tends to push these process gases outwards and away from the wafer. Thus, process gas delivered from the gas distribution holes outside the wafer overlap region 110 can essentially be considered excess or wasted process gas. As described above, in some embodiments, the number of gas distribution holes located outside the wafer overlap region can be reduced or eliminated to reduce or eliminate the amount of excess or wasted gas generated by the DPF spray head. However, doing so may require extensive customization of numerous radially symmetrical gas distribution features (in fact, they may no longer be reasonably considered "radially symmetrical gas distribution features") to ensure that the gas flow rate through the gas distribution holes remains uniform. By incorporating radially symmetric gas distribution features and / or gas distribution holes located outside the wafer overlap region 110, the flow splitting occurring at each radially symmetric gas distribution feature remains identical for all radially symmetric gas distribution features in the fractal layer. This results in a uniform flow rate through the gas distribution holes of each filling chamber without requiring complex modifications to the radially symmetric gas distribution features in the fractal layer 122. It is also noted that as the overall size of the radially symmetric gas distribution features becomes increasingly miniaturized, they may become increasingly susceptible to minute dimensional changes, making it increasingly difficult to individually fine-tune the airflow characteristics of each radially symmetric gas distribution feature through customization. Therefore, although the method shown with respect to the exemplary DPF spray head 100 may result in some excess or wasted gas, the resulting process gas distribution across the entire wafer is substantially uniform without requiring customized modifications to the radially symmetric gas distribution features in the fractal layer.

[0066] As previously described, a gas distribution orifice—a central orifice—is located on the underside of the DPF spray head 100 and is not part of any orifice pattern. Such central orifices may be included to facilitate additional wafer processing uniformity and may be fluidly connected to, for example, the inlet of the first gas chamber. Depending on the required specific process conditions, the central orifice may need to be sized to be the same as other gas distribution orifices in the first gas chamber, or alternatively larger or smaller than the others. In embodiments using a central orifice with the same size as other first gas distribution orifices, the flow rate through the central orifice can be modified in some of these embodiments by changing the flow path resistance from the first inlet through the spray head to the central orifice; it need not have the same flow resistance as the other first gas distribution orifices in the first gas chamber.

[0067] It will be further noted that although the present invention is primarily directed to dual-chamber fractal spray heads, similar principles can be implemented, for example, in single-chamber fractal spray head forms by simply omitting one of the air chambers and related features. Such single-chamber fractal (SPF) spray heads are also considered to fall within the scope of the present invention.

[0068] The DPF (and SPF) spray heads according to the concepts discussed herein can be used in semiconductor processing operations as previously discussed. For example, DPF or SPF spray heads can be used in semiconductor processing chambers (e.g., semiconductor processing chamber 170 in FIG. 19). Such DPF or SPF spray heads 100 can be suspended within chamber 170 via rods 176, which may include gas supply channels for delivering process gases to the inlet of the DPF or SPF spray head for distribution across the entire wafer 174, which can be supported within chamber 170 via base 172.

[0069] In some embodiments, a controller may be provided. The controller may be part of a system (including the examples described above) and may be operatively connected to various valves, mass flow controllers, pumps, etc., to receive information from and / or control such devices. Such systems may include semiconductor processing equipment comprising a processing tool or multiple tools, a chamber or multiple chambers, a processing platform or multiple platforms, and / or specific processing components (wafer pedestals, gas flow systems, etc.). Such systems may be combined with electronic equipment to control the operation of semiconductor wafers or substrates before, during, and after processing. Such electronic equipment may refer to a “controller” that controls various components or sub-components of the system or multiple systems. Depending on the processing conditions and / or system type, the controller may be programmable to control any process disclosed herein, including the delivery of various gases (e.g., to DPF or SPF spray heads as described herein), temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, flow rate settings, fluid delivery settings, and position and operation settings.

[0070] Broadly speaking, a controller can be defined as an electronic device having various integrated circuits, logic, memory, and / or software for receiving instructions, issuing instructions, controlling operations, initiating cleaning operations, initiating endpoint measurements, and the like. Integrated circuits may include: a chip in the form of firmware storing program instructions, a digital signal processor (DSP), a chip defined as an application-specific integrated circuit (ASIC), and / or one or more microprocessors, or a microcontroller that executes program instructions (e.g., software). Program instructions may be transmitted to the controller in the form of various individual settings (or program files), which define operating parameters for implementing (on a semiconductor wafer, or for a semiconductor wafer, or for a system) a specific process. In some implementations, the operating parameters may be part of a formulation defined by a process engineer to achieve one or more processing steps during the manufacturing process of one or more of the following: layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer grains.

[0071] In some embodiments, the controller may be part of a computer, or coupled to a computer that is integrated with, coupled to, or connected to the system via other networks, or a combination thereof. For example, the controller may be in all or part of a cloud-based or factory mainframe computer system that allows remote access to wafer processing. The computer may enable the system to remotely access the system to monitor the current progress of manufacturing operations, examine the history of past manufacturing operations, examine trends or performance metrics from multiple manufacturing operations, change parameters of the current process, set processing steps after the current process, or start a new process. In some examples, a remote computer (e.g., a server) may provide process recipes to the system via a network, which may include a local area network or the Internet. The remote computer may include a user interface that allows parameter and / or setting input or programming, which can then be transmitted from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify parameters for each processing step to be performed during one or more operations. It should be understood that parameters can be specific to the type of process to be performed and the type of tool with which the controller is coupled or controlled. Therefore, as described above, the controller can be distributed, for example, by comprising one or more separate controllers that are networked together and operate toward a common purpose (e.g., the process and control described herein). An example of a distributed controller for this purpose is one or more integrated circuits on the chamber that communicate with one or more integrated circuits located remotely (e.g., at the platform level or as part of a remote computer), and the two are combined to control the process on the chamber.

[0072] Exemplary systems may include, but are not limited to, plasma etching chambers or modules, deposition chambers or modules, rotary cleaning chambers or modules, metal-coated chambers or modules, cleaning chambers or modules, beveled edge etching chambers or modules, physical gas phase deposition (PVD) chambers or modules, chemical gas phase deposition (CV) D) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etching (ALE) chambers or modules, ion implantation chambers or modules, developer (track) chambers or modules, and any other semiconductor processing system that may be associated with, or used, in the manufacture and / or processing of semiconductor wafers.

[0073] As described above, depending on the process steps or plural steps to be performed with recourse to the tool, the controller may communicate with one or more of the following in a semiconductor manufacturing plant: other tool circuits or modules, other tooling components, cluster tools, other tool interfaces, adjacent tools, adjacent tools, tools distributed throughout the plant, a master computer, another controller, or a tool port used in a material carrying or to and from the tool port for use in material transport.

[0074] For the purposes of the present invention, the term "fluid connection" is used with respect to volumes, inflation chambers, orifices, etc. that may be interconnected to form a fluid connection, which is analogous to the use of the term "electrical connection" with respect to components connected together to form an electrical connection. Where the term “fluid interposition” is used, it may be used to refer to a component, volume, inflation chamber, or orifice fluidly connected to at least two other components, volumes, inflation chambers, or orifices such that from such other component, volume, inflation chamber or one of the orifices The fluid flowing to such other component, volume, inflation chamber, or the other in the orifice flows through the component of “fluid interposition” before reaching the other component, volume, inflation chamber, or the other in the orifice. For example, if pump fluid is inserted between the vessel and the outlet, the fluid flowing from the vessel to the outlet will flow through the pump before reaching the outlet.

[0075] It will be further understood that the general term “vertical port” may be used herein not only to refer to the vertical pipe port of each radially symmetric gas distribution feature, but also to refer herein to the feed vertical pipe port and gas distribution hole. Thus, for example, a gas distribution orifice can be described not only as a gas distribution orifice but also as a vertical pipe port. Similarly, the feed vertical pipe port can also be referred to as the vertical pipe port. In general, the vertical pipe port on the lowermost surface of the DPF or SPF spray head (when the spray head is installed in the treatment chamber) can also be referred to as a “gas distribution hole”.

[0076] It should be understood that the phrase “for each of the one or more items”, “for each of the one or more items”, or similar phrases used herein include both a single group of items and multiple groups of items. That is, the use of the phrase “for each of…” means that, in a programming language, it is used to refer to each item in the entire group of items referred to. For example, if the group of items referred to is a single item, then “each” will refer only to that single item (although in fact, the dictionary definition of “each” is often defined as “each of two or more things”), and does not mean that at least two of such items must exist.

[0077] It should also be understood that the term "layer" as used in this invention may refer to a physically separable layer (e.g., a layer in a laminated structure that is then joined, fused, or otherwise fixed in place relative to another layer in the laminated structure), or more generally, to the area of ​​a structure bonded between two reference surfaces; such structures may be composed of multiple components assembled or joined together, or in some instances may be an integral structure (e.g., a single-piece structure). For example, a single-piece component made by casting or lamination may still be considered to have features on its different "layers," even if the component is not built by actually joining physically separate layers together (although it can be said that most laminated components inherently have a layered structure because they are typically printed one thin layer at a time). It will also be understood that the "layers" of a component actually made as a laminate (i.e., derived from discrete layers) are not necessarily aligned with one of those discrete layers. For example, a layer of a component can be defined as including only a portion of such a discrete layer component, a portion of one of two adjacent discrete layer components, or a portion of one or two non-adjacent discrete layer components and the discrete layer component in between. [Simplified Explanation of the Diagram]

[0020] The various embodiments disclosed herein are illustrated in the accompanying drawings by way of example rather than limitation, and similar reference numerals refer to similar elements.

[0021] Figure 1 shows an isometric view of an exemplary dual-inflatable-chamber fractal spray head.

[0022] Figure 2 shows the reverse isometric view of the exemplary dual-inflatable chamber fractal spray head of Figure 1.

[0023] Figures 3 and 4 respectively show the top and bottom views of the exemplary dual-inflatable chamber fractal spray head in Figure 1.

[0024] Figure 5 shows an isometric exploded view of the exemplary dual-inflatable-chamber fractal spray head in Figure 1.

[0025] Figure 6 shows a detailed diagram of an exemplary first radially symmetric gas distribution feature.

[0026] Figure 7 shows a detailed diagram of an exemplary first radially symmetric gas distribution feature.

[0027] Figure 8 shows a size comparison between the radially symmetric gas distribution feature groups from each of the three different fractal layers.

[0028] Figure 9 provides a view of the relative proportions of gas distribution characteristics from different fractal layers.

[0029] Figures 10 to 15 show plan views of the multiple layers of the exemplary dual-inflatable chamber fractal spray head of Figure 1.

[0030] Figure 16 shows an isometric view of the volume of one air chamber inside the exemplary dual-air-chamber fractal spray head of Figure 1.

[0031] Figure 17 shows an isometric view of the volume of another air chamber inside the exemplary dual-air-chamber fractal spray head of Figure 1.

[0032] Figure 18 shows an isometric view of the volume of the two air chambers inside the exemplary dual-air-chamber fractal spray head in Figure 1.

[0033] Figure 19 shows a schematic diagram of a semiconductor processing chamber having a spray head as described herein.

[0034] Figures 1-18 are drawn to scale in each figure, but the scale between figures may vary. The figures only illustrate examples of the concepts discussed herein, and it will be readily understood that the concepts discussed herein can be implemented in a large number of alternative implementations, all of which are considered to fall within the scope of this invention.

Claims

1. A semiconductor processing apparatus, comprising: A spray head includes: a body having a first side and a second side facing in a direction opposite to the first side; one or more first gas chamber inlets; one or more second gas chamber inlets; a plurality of first gas distribution holes disposed throughout the second side; a plurality of second gas distribution holes disposed throughout the second side; and a plurality of first radially symmetrical gas distribution features and a plurality of second radially symmetrical gas distribution features, the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features comprising multiple sets of the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features located entirely within a cylindrical volume defined by a circular wafer overlap region, wherein: each first radially symmetrical gas distribution feature includes a first central gas chamber and a plurality of first spoke channels, each of the plurality of first spoke channels radiating outward from the first central gas chamber and terminating at a corresponding first distal end. Each second radially symmetrical gas distribution feature includes a second central filling chamber and a plurality of second spoke channels, each of which radiates outward from the second central filling chamber and terminates at a corresponding second distal end. In the group of first and second radially symmetrical gas distribution features, the first distal ends of the first spoke channels of the first radially symmetrical gas distribution features are located between adjacent pairs of second central filling chambers of the second radially symmetrical gas distribution features. In the group of first and second radially symmetrical gas distribution features, the second distal ends of the second spoke channels of the second radially symmetrical gas distribution features are located between adjacent pairs of first distal ends. The first radially symmetrical gas distribution features define a plurality of first flow paths within the body, and the second radially symmetrical gas distribution features define a plurality of second flow paths within the body. Each first flow path fluidly connects one of the first gas distribution holes to one of the one or more first inflation chamber inlets within the body, and each second flow path fluidly connects one of the second gas distribution holes to one of the one or more second inflation chamber inlets within the body.

2. The semiconductor processing apparatus as claimed in claim 1, wherein, within the body, the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features in each group are common amounts separated from the second side.

3. The semiconductor processing apparatus as claimed in claim 2, wherein within the main body, the first radially symmetrical gas distribution characteristics and the second radially symmetrical gas distribution characteristics of each group are separated from the second side by different amounts.

4. The semiconductor processing apparatus as described in claim 3, wherein, For each pair of adjacent groups of the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features: the first spoke channels in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of the pair of adjacent groups closer to the second side are shorter than the first spoke channels in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of the pair of adjacent groups farther from the second side, and the second spoke channels in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of the pair of adjacent groups closer to the second side are shorter than the second spoke channels in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of the pair of adjacent groups farther from the second side.

5. The semiconductor processing apparatus as described in claim 3, wherein, For each pair of adjacent groups of the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features: the length of the first spoke channels in the pair of adjacent groups of the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features closer to the second side is half the length of the first spoke channels in the pair of adjacent groups of the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features farther from the second side, and the length of the second spoke channels in the pair of adjacent groups of the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features closer to the second side is half the length of the second spoke channels in the pair of adjacent groups of the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features farther from the second side.

6. The semiconductor processing apparatus as described in claim 1, wherein: Each of the first spoke channels in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of each group extends along a corresponding axis that does not intersect with any of the second central air chambers in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of each group, and each of the second spoke channels in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of each group extends along a corresponding axis that intersects with at least one of the first central air chambers in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of each group.

7. The semiconductor processing apparatus as described in claim 1, wherein: Each group of first radially symmetrical gas distribution features and second radially symmetrical gas distribution features has four first spoke channels radiating outward from each of the first central air chambers of at least some of the first radially symmetrical gas distribution features, and each group of first radially symmetrical gas distribution features and second radially symmetrical gas distribution features has four second spoke channels radiating outward from each of the second central air chambers of at least some of the second radially symmetrical gas distribution features.

8. The semiconductor processing apparatus as described in claim 1, wherein: The first gas distribution holes within the cylindrical volume are arranged in a first square pattern with a first spacing, and the second gas distribution holes within the cylindrical volume are arranged in a second square pattern with a second spacing, wherein the first spacing is equal to the square root of two times the square of the second spacing.

9. The semiconductor processing apparatus as described in claim 1, wherein: The first distal end of each of the first spoke channels in the group of first radially symmetrical gas distribution features and second radially symmetrical gas distribution features closest to the second side is connected to a corresponding first gas distribution hole in the group of first gas distribution holes via a corresponding first vertical tube channel, and the second distal end of each of the second spoke channels in the group of first radially symmetrical gas distribution features and second radially symmetrical gas distribution features closest to the second side is connected to a corresponding second gas distribution hole in the group of second gas distribution holes via a corresponding second vertical tube channel.

10. The semiconductor processing apparatus as described in claim 9, wherein: The first distal end of each of the first spoke channels in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of the groups that are not closest to the second side is connected via a corresponding first vertical channel to a first central air chamber in one of the first central air chambers in an adjacent group of the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of the groups that are closer to the second side. The second distal end of each of the second spoke channels in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of the groups that are not closest to the second side is connected via a corresponding second vertical channel to a second central air chamber in one of the second central air chambers in an adjacent group of the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of the groups that are closer to the second side.

11. The semiconductor processing apparatus as described in claim 1, wherein: The first radially symmetric gas distribution features are arranged in a first fractal pattern, and the second radially symmetric gas distribution features are arranged in a second fractal pattern, with the first fractal pattern and the second fractal pattern overlapping each other.

12. The semiconductor processing apparatus as described in claim 1, wherein: Each of the first central air chambers in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of each group is located at the midpoint between two second central air chambers in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of each group, and each of the second central air chambers in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of each group is located at the midpoint between two first central air chambers in the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features of each group.

13. The semiconductor processing apparatus as described in claim 1, wherein: The first spoke channels are each aligned with one of two orthogonal first channel axes, the second spoke channels are each aligned with one of two orthogonal second channel axes, and the first channel axes and the second channel axes are 45° out of phase.

14. The semiconductor processing apparatus as described in any one of claims 1 to 13, wherein: The main body comprises multiple layers, wherein the first radially symmetrical gas distribution features and the second radially symmetrical gas distribution features in each group are formed in one of the corresponding layers, and the layers are fused together to form a laminated structure.

15. The semiconductor processing apparatus as claimed in claim 14, wherein the layers are made of a ceramic material.

16. The semiconductor processing apparatus as described in any one of claims 1 to 13, further comprising: a processing chamber; and a base, wherein: The base is positioned within the processing chamber, and the spray head is positioned within the processing chamber and above the base.

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