Space atomic layer stacking

Abstract

To provide spatial atomic layer deposition.SOLUTION: Systems and methods are provided herein to improve the efficiency of an atomic layer deposition (ALD) cycle by providing an improved purge block design. An improved purge block prevents gas mixing, regardless of rotational speed of a platen, by providing a lower cavity on an underside of the purge block, and in some embodiments, by providing an upper cavity on a topside of the purge block. The lower / upper cavity provides a gas conduction path that distributes purge gas evenly beneath / above the purge block and provides uniform gas flow conductance within the lower / upper cavity. Compared to conventional purge block designs, the improved purge block design described herein provides a narrower, yet more effective isolation barrier, which prevents gas mixing even at high rotational speeds of the platen.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 041,882, filed June 20, 2020, which is incorporated herein by reference.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates to the processing of substrates. In particular, the present disclosure provides an apparatus and method for processing a surface of a substrate. [Background technology]

[0003] Atomic layer deposition (ALD) is a known technique for forming layers on a substrate. In atomic layer deposition, a substrate is cyclically exposed to alternating gas species (or precursors). The gas species react with the surface of the substrate in a self-limiting or nearly self-limiting manner. By repeating the cycle of alternating gas species, thin films can be gradually formed.

[0004] A variety of processing tools can be used in atomic layer deposition processes. For example, batch furnace-type systems can be used. Single-substrate systems, in which a processing chamber is filled with gas and evacuated for a single substrate, can also be used. Yet another system is a spatial ALD system. In a spatial ALD system, the substrate passes at relatively high speed through multiple gas sources (e.g., gas injectors, gas showerheads, or gas showerheads with injector outlets), which inject the gases necessary to perform the ALD processing steps near the substrate surface as the substrate rotates in a cyclical manner.

[0005] Spatial ALD relies on the rapid movement of a substrate between alternating gas streams that are separated from one another. For example, in one exemplary spatial ALD process for forming silicon nitride, the substrate surface may be exposed to a silicon-containing precursor gas (e.g., dichlorosilane, DCS, etc.), followed by sequential exposure of the substrate surface to a nitrogen-containing precursor gas (e.g., ammonia, NH3, etc.). In spatial ALD systems, the substrate is often rotated in rapid succession between NH3 and DCS precursor gases to build up alternating layers of silicon (Si), and then the silicon is converted to silicon nitride (SiN) by exposure to NH3 until the target thickness is achieved. To avoid gas mixing, the precursor gas streams (DCS, NH3) are typically separated by a physical barrier, a purge source, or a combination of the two.

[0006] FIG. 1 illustrates an example of a conventional spatial ALD system that can be used to achieve an atomic layer deposition process. More specifically, FIG. 1 provides a top view of a substrate processing tool 100 (i.e., a spatial ALD system) as seen inside a processing chamber 105 of the substrate processing tool 100. As shown in FIG. 1, a platen 110 is provided within the processing chamber 105 to hold one or more substrates 115. Each of the substrates 115 may be disposed on a susceptor (112, FIG. 2) that provides heat to the substrate. Multiple showerheads and purge blocks may also be provided within the processing chamber 105 and positioned above the platen 110 to provide various gases to the substrate. A gas outlet pumping port 130 may also be provided.

[0007] In the conventional spatial ALD system shown in FIG. 1 , a first showerhead 120 is disposed above the platen 110 to provide a first precursor gas (e.g., DCS) to one or more substrates 115, and a second showerhead 125 is disposed above the platen 110 to provide a second precursor gas (e.g., NH ) to one or more substrates 115. In FIG. 1 , the first showerhead 120 accounts for approximately 45° of a 360° ALD cycle, and the second showerhead 125 accounts for approximately 79° of the ALD cycle. As the platen 110 rotates (as indicated by the arrows), one or more substrates 115 are moved sequentially under the first showerhead 120 and then under the second showerhead 125 to perform one cycle of an atomic layer deposition process. Rotation of the platen 110 and substrates 115 may be repeated for multiple ALD cycles. Although not shown in FIG. 1, a controller can be provided to control various operating parameters of the spatial ALD system, including, for example, temperature, gas flow, pressure, rotation speed, number of ALD cycles, etc.

[0008] In some ALD processes, the platen 110 may be rotated at a relatively high speed to reduce processing time and costs. The faster the platen 110 rotates, the faster the target film thickness will be reached. However, as the rotation speed increases (e.g., above 10 revolutions per minute (RPM)), the likelihood of gas mixing increases unless significant measures are taken. Gas mixing is due to viscous drag and occurs when gases impinging on the susceptor surface are carried by the platen 110 as it rotates. Unless the gas layer can be mechanically confined by a physical barrier, purged with an inert gas (such as nitrogen), or an appropriate combination of both, gas mixing will occur if the rotation speed exceeds a certain point.

[0009] 1 , purge block 128 provides a gas purge (e.g., an argon, nitrogen, or other inert gas purge) after substrate 115 rotates past each showerhead to prevent precursor gases from mixing. A conventional purge block 128 can be configured in any number of ways, such as a line of gas injectors, a line of gas injectors in separate, divided zones, a showerhead, etc. In the spatial ALD system shown in FIG. 1 , purge block 128 is implemented as a showerhead with a central line of gas injectors.

[0010] FIG. 2 provides a cross-sectional view through one of the purge blocks 128 shown in FIG. 1 as a substrate 115 disposed on a susceptor 112 rotates beneath the purge block 128. In the conventional design shown in FIG. 2, the purge block 128 combines a wide (e.g., 60°) mechanical barrier 200 with a centrally located purge gas injector 210. The purge gas injector 210, located within a narrow conduction path 220 on the underside of the purge block 128, includes multiple ports 230 for injecting purge gas into a processing space 240 disposed above the substrate 115. In some cases, a second purge gas injector 250 may also be provided to inject purge gas above the purge block 128 when the purge block is not directly bolted to the chamber lid 260. In such cases, the second purge gas injector 250 may be used to prevent precursor diffusion through the gap between the chamber lid 260 and the upper side of the purge block 128.

[0011] To prevent the precursor gases from mixing within the process space 240, the purge block 128 provides a purge gas (e.g., argon, nitrogen, or another inert gas) to the substrate surface as the platen 110 rotates about the central axis of the substrate processing tool 100. At slow rotation speeds (e.g., less than 10 RPM), the purge gas provided by the purge gas injector 210 in combination with the wide mechanical barrier 200 can provide an effective separation barrier to prevent the precursor gases from mixing. While the purge blocks 128 shown in FIGS. 1 and 2 can effectively separate the precursor gases at slow rotation speeds, they take up a large portion of the ALD cycle, lack efficiency, and often cannot prevent gas mixing at higher rotation speeds (e.g., greater than 10 RPM).

[0012] For example, gas flow conductance through the conductive path 220 is linearly proportional to the wall thickness (T) between the side end of the conductive path 220 and the side end of the purge block 128, decreasing as the wall thickness (T) increases (and vice versa). In the purge block design shown in FIGS. 1 and 2, the gas flow conductance near the outer edge of the platen 110 (where T is larger) is less than the gas flow conductance near the central axis (where T is smaller). Because the gas flow conductance is non-uniform and varies significantly along the radial axis of the purge block 128, more purge gas must be injected into the outer region of the purge block 128 to prevent gas mixing, even when the platen 110 rotates at low rotational speeds. Because higher rotational speeds result in greater radial velocities (especially near the outer edge of the platen 110), a proportionally greater amount of purge gas is required to resist viscous drag and prevent gas mixing at higher rotational speeds.

[0013] 1 and 2 relies on a purge gas injector 210 design that places a higher density of ports 230 near the outer edge of the platen 110 where more purge gas volume is needed. While such an injector design can be used to increase the amount of purge gas near the outer edge of the platen 110, the purge block 128 design shown in FIGS. 1 and 2 often cannot prevent gas mixing at high rotational speeds (e.g., above 10 RPM) due to the uneven gas flow conductance provided along the radial axis of the purge block.

[0014] In addition to not effectively preventing gas mixing at high rotation speeds, the purge block 128 shown in Figures 1 and 2 consumes a large portion of the ALD cycle. For example, approximately one-third (e.g., 120°) of the ALD cycle is consumed under the purge block 128 shown in Figures 1 and 2, leaving only two-thirds of the cycle for exposure to precursor gases. However, it is generally desirable to maximize the time spent under the precursor gas streams to minimize ALD cycle time. If purging is more efficient, shorter ALD cycles can be achieved for a given fixed precursor exposure time, thereby providing a lower-cost process with higher wafer throughput.

[0015] Therefore, it would be desirable to provide a system and method that improves the efficiency of ALD cycles by providing improved purge block designs. Summary of the Invention [Means for solving the problem]

[0016] Provided herein are systems and methods for improving the efficiency of atomic layer deposition (ALD) cycles by providing an improved purge block design. The improved purge block prevents gas mixing regardless of platen rotation speed by providing a lower cavity below the purge block and, in some embodiments, an upper cavity above the purge block. The lower / upper cavities provide gas conduction paths that evenly distribute purge gas below / above the purge block and provide uniform gas flow conductance within the lower / upper cavities. Compared to conventional purge block designs, the improved purge block design described herein provides a narrower but more effective separation barrier, preventing gas mixing even at high platen rotation speeds.

[0017] According to one embodiment, a spatial atomic layer deposition (ALD) system is provided herein, including a platen carrying one or more substrates, the platen rotating 360° around a central axis of the spatial ALD system, a first showerhead disposed above the platen for providing a first process gas to the one or more substrates as the platen rotates, and a purge block disposed above the platen for providing a purge gas to the one or more substrates after the first process gas has been provided to the one or more substrates. In this embodiment, the purge block includes a lower cavity formed below the purge block and a first purge gas injector disposed within the lower cavity for injecting a purge gas below the purge block. The lower cavity provides a gas conduction path that distributes the purge gas below the purge block so that the purge gas flows evenly along the side edges of the purge block in a direction perpendicular to the side edges of the purge block.

[0018] In some embodiments, the contour of the lower cavity may be similar to but smaller than the contour of the purge block, resulting in a uniform wall thickness along a majority of the purge block. In such embodiments, the uniform wall thickness may be measured between a side edge of the lower cavity and a side edge of the purge block. In some embodiments, the uniform wall thickness may be selected from a range including 20 mm to 80 mm. In other embodiments, the wall thickness in one or more regions of the purge block may differ from the wall thickness in other regions of the purge block, thereby varying the gas flow conductance provided within the lower cavity in one or more regions of the purge block.

[0019] In some embodiments, the purge block may further include an upper cavity formed on an upper side of the purge block and a second purge gas injector for injecting a second purge gas onto the purge block. If included, the upper cavity may provide a gas conduction path that distributes the second purge gas onto the purge block so that the second purge gas flows evenly along the side edges of the purge block in a direction perpendicular to the side edges of the purge block.

[0020] In some embodiments, the contour of the upper cavity may be similar to but smaller than the contour of the purge block, resulting in a uniform wall thickness along a majority of the purge block. In such embodiments, the uniform wall thickness may be measured between the gas conduction path provided within the upper cavity and the side edge of the purge block. In some embodiments, the uniform wall thickness may be selected from a range including 20 mm to 80 mm. In other embodiments, the wall thickness in one or more regions of the purge block may differ from the wall thickness in other regions of the purge block, thereby varying the gas flow conductance provided within the upper cavity in one or more regions of the purge block.

[0021] In some embodiments, the width of the purge block can cover a portion of a 360° rotation of the platen, the portion being selected from a range including 10° to 40° of the 360° rotation of the platen. In one exemplary embodiment, the width of the purge block can cover 20° of the 360° rotation of the platen. In another exemplary embodiment, the width of the purge block can cover 30° of the 360° rotation of the platen.

[0022] According to another embodiment, provided herein is a spatial ALD system including a platen carrying one or more substrates, the platen rotating 360° about a central axis of the spatial ALD system, a first showerhead disposed above the platen to provide a first process gas to the one or more substrates as the platen rotates, and a purge block disposed above the platen to provide a purge gas to the one or more substrates after the first process gas has been provided to the one or more substrates. In this embodiment, the width of the purge block can cover a portion of the 360° rotation of the platen, the portion being selected from a range including 10° to 40° of the 360° rotation of the platen. In one implementation, for example, the width of the purge block can cover 20° to 30° of the 360° rotation of the platen.

[0023] In some embodiments, the purge block may include a lower cavity formed below the purge block and a first purge gas injector disposed within the lower cavity for injecting purge gas below the purge block. The lower cavity may provide a gas conduction path that distributes the purge gas below the purge block so that the purge gas flows evenly along the side edges of the purge block in a direction perpendicular to the side edges of the purge block.

[0024] In some embodiments, the contour of the lower cavity may be similar to but smaller than the contour of the purge block, resulting in a uniform wall thickness along the majority of the purge block. In such embodiments, the uniform wall thickness may be measured between the gas conduction path provided within the lower cavity and the side edge of the purge block.

[0025] In some embodiments, the purge block may further include an upper cavity formed on an upper side of the purge block and a second purge gas injector for injecting a second purge gas onto the purge block. A gas conduction path may be provided to distribute the second purge gas onto the purge block so that the second purge gas flows evenly along the side edges of the purge block in a direction perpendicular to the side edges of the purge block.

[0026] In some embodiments, the contours of the lower and upper cavities may be similar to but smaller than the contours of the purge block, resulting in a uniform wall thickness along a majority of the purge block. In such embodiments, the uniform wall thickness may be measured between the side edges of the lower and upper cavities and the side edges of the purge block. For example, the uniform wall thickness may be selected from a range including 20 mm to 80 mm. In other embodiments, the wall thickness in one or more regions of the purge block may differ from the wall thickness in other regions of the purge block, thereby varying the gas flow conductance provided within the lower and upper cavities in one or more regions of the purge block.

[0027] According to yet another embodiment, provided herein is a method for processing a substrate in a spatial ALD system, the spatial ALD system including a platen and a purge block disposed above the platen to provide a purge gas to a processing space above the substrate. The method may generally include: providing a substrate on the platen; sequentially exposing the substrate to a first processing gas and a second processing gas as the platen rotates about a central axis of the spatial ALD system; injecting a purge gas into a lower cavity formed below the purge block after exposing the substrate to the first processing gas and before exposing the substrate to the second processing gas; and distributing the purge gas within the lower cavity to prevent the first processing gas and the second processing gas from mixing in the processing space, thereby causing the purge gas to flow evenly along a side edge of the purge block in a direction perpendicular to the side edge of the purge block.

[0028] In some embodiments, when the purge gas is injected into the lower cavity, the method may further include injecting a second purge gas into an upper cavity formed above the purge block, and distributing the second purge gas within the upper cavity so that the second purge gas flows evenly along the side edges of the purge block in a direction perpendicular to the side edges of the purge block.

[0029] In some embodiments, the method can further include rotating the platen at a high rotational speed of greater than 10 revolutions per minute (RPM). By injecting and distributing a purge gas into the lower cavity, the first process gas is separated from the second process gas even when the platen is rotated at a high rotational speed.

[0030] A more detailed understanding of the present invention and its advantages may be obtained by reference to the following description in conjunction with the accompanying drawings, in which like reference numerals indicate like features, and in which it is noted, however, that the accompanying drawings illustrate only exemplary embodiments of the disclosed concepts and therefore should not be considered limiting in scope, as other equally effective embodiments of the disclosed concepts may also be permissible. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 (Prior Art) is a top view showing a conventional spatial atomic layer deposition (ALD) system in which multiple purge blocks are used to prevent reactant gases from mixing. [Figure 2] FIG. 2 (Prior Art) is a cross-sectional view through one of the purge blocks shown in FIG. [Figure 3] FIG. 3 is a top-down view illustrating one embodiment of a spatial ALD system having a narrower, more efficient purge block. [Figure 4] FIG. 4 is a top-down view illustrating another embodiment of a spatial ALD system having a narrower, more efficient purge block. [Figure 5]FIG. 5 is a cross-sectional view through one of the purge blocks shown in FIGS. 3 and 4, showing the upper and lower cavities formed within the purge block. [Figure 6] FIG. 6 is a perspective view of the underside of one of the purge blocks shown in FIGS. 3 and 4, illustrating an example of a lower cavity formed therein. [Figure 7] FIG. 7 is a perspective view of the top of one of the purge blocks shown in FIGS. 3 and 4, illustrating an example of an upper cavity formed therein. [Figure 8] FIG. 8 is a flow chart diagram illustrating an exemplary method for utilizing the techniques disclosed herein. DETAILED DESCRIPTION OF THE INVENTION

[0032] Provided herein are systems and methods for improving the efficiency of atomic layer deposition (ALD) cycles by providing an improved purge block design. Compared to conventional purge block designs, the improved purge block design described herein provides a narrower but more effective isolation barrier, preventing gas mixing even at high rotational speeds (e.g., greater than 10 RPM).

[0033] In disclosed embodiments, an improved purge block prevents gas mixing regardless of platen rotation speed by providing a lower cavity below the purge block and, in some embodiments, an upper cavity above the purge block, which provides a gas conduction path that evenly distributes purge gas below (and above) the purge block and provides uniform gas flow conductance within the lower cavity (and upper cavity).

[0034] Uniform gas flow conductance is provided within the lower cavity (and upper cavity) by providing a relatively wide conduction path for the purge gas to flow. In the disclosed embodiment, the wide conduction path is provided by forming the lower / upper cavities so that their contours are similar to, but smaller than, the contours of the purge block. This allows for a substantially uniform wall thickness (T) along the majority of the purge block. As used herein, uniform thickness has a variation of 15% or less. The wide conduction path provided within the lower / upper cavities allows the purge gas to evenly pressurize the volumes of the lower / upper cavities, thereby allowing the purge gas to (a) flow more evenly around the periphery of the purge block and (b) flow in a direction substantially perpendicular to the side edges of the purge block. This allows the improved purge block design to provide a more effective separation barrier, thereby preventing gas mixing, even at high rotational speeds (e.g., greater than 10 RPM).

[0035] 3 and 4 illustrate various embodiments of a spatial ALD system having a narrower, more efficient purge block. More specifically, FIGS. 3 and 4 provide a top-down view of the substrate processing tool 300 (i.e., a spatial ALD system) as seen inside the processing chamber 305 of the substrate processing tool 300. Similar to the substrate processing tool 100 shown in FIG. 1, the substrate processing tool 300 shown in FIGS. 3 and 4 includes a platen 310 within the processing chamber 305 for carrying one or more substrates 315. The platen 310 rotates 360° about the central axis of the substrate processing tool 300 to perform one or more cycles of an ALD process. Multiple showerheads 320, 325 and multiple purge blocks 328 are also provided within the processing chamber 305 and are positioned above the platen 310 to supply various gases to the substrate as the platen rotates. A gas outlet pumping port 340 is also provided within the processing chamber 305 for removing exhaust gases from the substrate processing tool 300.

[0036] 3 and 4, a first showerhead 320 and a second showerhead 325 are disposed above the platen 310 to provide various process gases to the substrate 315. In some embodiments, the first showerhead 320 can provide a first precursor gas to the substrate 315, and the second showerhead 325 can provide a second precursor gas to one or more substrates 315. In one exemplary ALD process for forming silicon nitride, the first precursor gas can be a silicon-containing precursor gas (e.g., dichlorosilane (DCS), etc.), and the second precursor gas can be a nitrogen-containing precursor gas (e.g., ammonia, NH3, etc.). However, it will be appreciated that the first showerhead 120 and the second showerhead 125 can provide other process gases (e.g., including reactive precursors, non-reactive precursors, and / or inert gases) to the substrate 315 when performing other ALD processes.

[0037] As the platen 310 rotates (as indicated by the arrow), the substrate 315 moves sequentially under a first showerhead 320 and then a second showerhead 325 to perform one cycle of an atomic layer deposition process. In the exemplary ALD process described above, the substrate 315 rotates under the first showerhead 320 to expose the substrate surface to a first precursor gas (e.g., DCS) before rotating under the second showerhead 325 to expose the substrate surface to a second precursor gas (e.g., NH). To prevent the first and second precursor gases from mixing, a purge block 328 provides a gas purge (e.g., argon (Ar), nitrogen (N), purge, or another inert gas purge) to the substrate surface after the substrate 315 rotates through each of the showerheads 320, 325. This process can be repeated for multiple ALD cycles until the target thickness of the silicon nitride layer is achieved. Although not shown in FIGS. 3 and 4 , a controller may be provided within or coupled to the substrate processing tool 300 to control various operating parameters of the spatial ALD system, including, for example, temperature, gas flow, pressure, rotation speed, number of ALD cycles, etc.

[0038] Unlike the substrate processing tool 100 shown in Figure 1, the substrate processing tool 300 shown in Figures 3 and 4 utilizes a narrower, more efficient purge block 328. In some embodiments, the purge block 328 shown in Figures 3 and 4 may consume up to 67% less area than the purge block 128 design shown in Figures 1 and 2. Utilizing a narrower purge block 328 design in the substrate processing tool 300 allows for reduced ALD cycle times and / or increased precursor exposure dose / time.

[0039] 3 illustrates one embodiment of a narrow purge block 328 design, which reduces the area consumed by the purge block by approximately 50% compared to the purge block 128 design shown in FIGS. 1 and 2. In the embodiment shown in FIG. 3, the purge blocks 328 each consume 30° of the ALD cycle. The narrow purge block 328 design shown in FIG. 3 allows the purge block to be physically separated from one or more showerheads (e.g., the first showerhead 320 and / or the second showerhead 325) included within the substrate processing tool 300. The physical separation between the purge block and the showerheads improves the amount of precursor delivered by the showerhead by reducing sinking of purge gas under the showerhead cover plate.

[0040] In one embodiment, the area (or portion of an ALD cycle) consumed by the first showerhead 320 and / or the second showerhead 325 may be similar to that shown in FIG. 1 and described above. For example, the first showerhead 320 may consume 45° of the ALD cycle, and the second showerhead 325 may consume 79° of the ALD cycle. When used in such an embodiment, the narrow purge block 328 design shown in FIG. 3 can improve the precursor volume delivered by the showerhead over the same ALD cycle time (if the rotation speed of the platen 110 is maintained) by reducing the sinking of purge gas under the showerhead cover plate. Alternatively, the narrow purge block 328 design shown in FIG. 3 can be used to reduce the ALD cycle time (by increasing the rotation speed of the platen 110) to the extent permitted by the increased precursor volume due to the reduced N sinking effect. In other embodiments, the narrow purge block 328 design shown in Figure 3 may allow for increased precursor dose / time by freeing up space for a larger showerhead. An example of this is shown in Figure 4.

[0041] 4 shows another embodiment of a narrow purge block 328 design, which reduces the area consumed by the purge block by approximately 67% compared to the purge block 128 design shown in FIGS. 1 and 2. In the embodiment shown in FIG. 4, the purge blocks 328 each consume 20° of the ALD cycle. The narrower purge block 328 design shown in FIG. 4 allows for an increase in the amount of precursor provided by one or more showerheads (e.g., first showerhead 320 and / or second showerhead 325) by increasing the size of the showerheads.

[0042] 4, the design of the narrow purge block 328 allows for the use of a much larger first showerhead 320 to increase the amount of precursor (and / or precursor exposure time) provided by the first showerhead. In one exemplary implementation, the first showerhead 320 shown in FIG. 4 may consume 135° of an ALD cycle, and the second showerhead 325 may consume 79° of an ALD cycle. By increasing the area (or portion of an ALD cycle) consumed by the first showerhead 320 (e.g., from 45° to 135°), the embodiment shown in FIG. 4 may increase the amount of precursor provided by the first showerhead 320 by a factor of three.

[0043] While examples of narrow purge block 328 designs are shown in FIGS. 3 and 4 and described above, the techniques described herein are not strictly limited to the few examples described above. In other embodiments, narrow purge block 328 according to the techniques described herein can consume a larger or smaller portion of the ALD cycle. For example, narrow purge block 328 can consume approximately 10°-40° of the ALD cycle while retaining the benefits described herein.

[0044] In the above examples, the widths of the first showerhead 320, the second showerhead 325, and the purge block 328 are described as an angular measurement (expressed in degrees) of one ALD cycle. This description assumes that one ALD cycle is performed per 360° rotation of the platen 310. However, some spatial ALD systems may perform more than one ALD cycle per 360° rotation of the platen 310. To describe such systems, the widths of the first showerhead 320, the second showerhead 325, and the purge block 328 may alternatively be described as an angular measurement (expressed in degrees) of a 360° rotation of the platen 310. For example, the width of the purge block 328 may alternatively be described as covering a portion of a 360° rotation of the platen 310, the portion being selected from a range including about 10° to about 40° of a 360° rotation of the platen 310. 3 and 4, the widths of the purge block 328 cover approximately 30° and approximately 20°, respectively, of a 360° rotation of the platen 310. Other widths covering alternative angular measurements may also be used for the purge block 328.

[0045] In addition to reducing the portion of the ALD cycle consumed by gas purging, the techniques described herein improve purge gas efficiency and prevent gas mixing, even at high rotational speeds (e.g., greater than 10 RPM). As explained in more detail below, the disclosed techniques improve purge gas efficiency by providing a lower cavity below the purge block 328, which provides a high-gas conductance passageway for evenly distributing the purge gas below the purge block. In some embodiments, an upper cavity may similarly be provided above the purge block 328 to evenly distribute the purge gas above the purge block. In some embodiments, purge gas flow from the purge block 328 may be further controlled by providing customized gas conduction paths in the lower cavity (and optionally the upper cavity) that distribute the purge gas flux as needed to compensate for radial variations in the speed of the platen 310. This allows the disclosed purge block 328 design to separate process gases even at high rotational speeds (e.g., greater than 10 RPM) without increasing the purge gas volume.

[0046] 5-7 provide various embodiments of improved purge block designs in accordance with the technology described herein. Specifically, FIG. 5 provides a cross-sectional view through one of the purge blocks 328 shown in FIG. 3 or 4 as a substrate 315 disposed on a susceptor 312 rotates beneath the purge block. As shown in FIG. 5, the purge block 328 may, in some embodiments, include both an upper cavity 327 and a lower cavity 329. In some embodiments, only the lower cavity may be utilized. The lower cavity 329 formed below the purge block 328 provides a lower volume (V L An upper cavity 327 formed above the purge block 328 includes an upper volume (V U ) is included.

[0047] 5, a first purge gas injector 350 is provided within the lower cavity 329 for injecting purge gas into a processing space 360 ​​disposed below the purge block 328 and above the substrate 315 from a gas input location generally proximate the central axis of the system. In one embodiment, the first purge gas injector 350 may extend completely through the lower cavity 329. Alternatively, the first purge gas injector 350 may extend partially through the lower cavity 329.

[0048] The first purge gas injector 350 may generally include multiple ports 355 for injecting a purge gas (e.g., Ar, N, or another inert purge gas) into the processing space 360. In some embodiments, the first purge gas injector 350 may include a higher density of ports 355 near the outer edge of the platen 310, such that the first purge gas injector 350 injects a greater purge gas volume near the outer edge of the platen 310. In some embodiments, the density of ports 355 may decrease toward the center of the susceptor 312. As noted above, providing a higher density of ports 355 near the outer edge of the platen 310 may provide a greater purge gas volume when needed to resist viscous drag and prevent gas mixing at higher rotational speeds. In other embodiments, the ports 355 may be evenly spaced along the radial axis of the first purge gas injector 350. In such embodiments, the improved purge block designs described herein can resist viscous drag to prevent gas mixing at higher rotational speeds.

[0049] In some embodiments, a second purge gas injector 370 may also be provided to inject a purge gas (e.g., Ar, N, or another inert purge gas) onto the purge block 328. For example, if the purge block 328 is not directly connected to the chamber lid 380, a gap (G) may be formed between the underside of the chamber lid 380 and the upper side of the purge block 328. In such embodiments, the second purge gas injector 370 may be used to inject purge gas into the upper cavity 327 of the purge block 328, thereby preventing diffusion of precursors through the gap. However, the second purge gas injector 370 is not strictly necessary and may be omitted in some embodiments if the purge block 328 is directly connected to the chamber lid 380. If the purge block 328 is directly connected to the chamber lid 380, the upper cavity 327 may also be omitted.

[0050] As the platen 310 rotates about the central axis of the substrate processing tool 300, the first purge gas injector 350 provides a purge gas (e.g., Ar, N2, or another inert purge gas) to the surface of the substrate 315 to prevent the precursor gases (e.g., DCS and NH3) from mixing within the processing space 360. As noted above, gas mixing is caused by viscous drag and occurs when gases impinging on the surface of the susceptor 312 are carried by the platen 310 as the platen rotates. As further noted above, the probability of gas mixing increases as the rotational speed of the platen 310 increases. Thus, at high rotational speeds (e.g., greater than 10 RPM), gas mixing may occur unless significant precautions are taken.

[0051] The design of the purge block 328 shown in Figures 3-7 effectively prevents gas mixing (i.e., provides nearly complete separation between the first and second precursor gases) regardless of the rotational speed of the platen 310 by providing a lower cavity 329 below the purge block 328 and (in some embodiments) an upper cavity 327 above the purge block. Unlike the narrow conduction path 220 shown in Figures 1 and 2, the upper and lower cavities 327 and 329 formed within the purge block 328 provide relatively wide conduction paths for the purge gas to flow (see Figures 5-7). The wide conduction paths provided within the upper and lower cavities 327 and 329 allow the purge gas to flow through the upper volume (V U ) and lower capacitance (V L ) can be evenly pressurized, thereby allowing the purge gas to (a) flow more evenly around the periphery of the purge block 328, and (b) flow in a direction substantially perpendicular to the side edges 330 of the purge block 328 (as shown by the arrows in FIGS. 3-4 ). By providing uniform gas flow conductance within the upper cavity 327 and / or lower cavity 329, the purge block 328 design shown in FIGS. 3-7 is more effective at preventing gas mixing (e.g., due to precursor gas sinking in the precursor sector or precursor gas sinking in the purge gas sector) than the conventional purge block 128 design shown in FIGS. 1 and 2 .

[0052] 6 and 7 provide perspective views of the design of the purge block 328 shown in FIGS. 3-5. More specifically, FIG. 6 provides a perspective view of the underside of the purge block 328, illustrating one example of a lower cavity 329 that may be formed therein. A top view of the purge block 328 is shown in FIG. 7, illustrating one example of an upper cavity 327 that may be formed on the upper side of the purge block 328. However, it will be appreciated that the lower cavity 329 and upper cavity 327 shown in FIGS. 6 and 7 are merely exemplary and represent only one example of a high gas conductance passageway or customized gas conduction path that may be included within the purge block 328 to (a) evenly distribute purge gas below / above the purge block 328 and / or (b) control gas conductance to compensate for radial variations in the velocity of the platen 310. In other embodiments, alternative configurations of the lower cavity 329 and / or upper cavity 327 may be used to provide the advantages disclosed herein. In some embodiments, the upper cavity 327 shown in FIGS. 5 and 7 may be omitted, for example, if the purge block is connected directly to the chamber lid 380.

[0053] Compared to the narrow conduction path 220 shown in FIGS. 1 and 2, gas flow conductance is improved within the upper cavity 327 and / or lower cavity 329 of the purge block 328 by reducing the wall thickness (T) to widen the conduction path through which the purge gas passes. As noted above, gas flow conductance through a conduction path is linearly proportional to the wall thickness (T) between the side edge of the conduction path and the side edge of the purge block, increasing as the wall thickness (T) decreases (and vice versa). In the design of the purge block 328 shown in FIGS. 3-7, the conduction path is provided by the upper cavity 327 and lower cavity 329 of the purge block 328. Therefore, the wall thickness (T) is measured between the side edge of the upper / lower cavity and the side edge of the purge block, as shown, for example, in FIGS. 5 and 6.

[0054] 6 and 7, the contours of the upper and lower cavities 327, 329 are similar to the contours of the purge block 328, resulting in a uniform wall thickness (e.g., T1, T2, T3, and T4 may be substantially equal to within about 15%) along most of the purge block 328. At the distal end of the purge block 328, the wall thickness (T5) may be increased, and a pass-through 326 may be provided to receive a first purge gas injector 350.

[0055] In some embodiments, the gas flow conductance within the upper cavity 327 and / or lower cavity 329 may be altered in one or more regions of the purge block 328 by varying the wall thickness (T) within those regions. As shown in Figure 6, for example, the wall thickness (T) may be varied along the radial axis of the purge block 328 to control the gas flow conductance within the lower cavity 329 by providing more (or less) purge gas flow within one or more regions of the purge block. For example, the wall thickness (T) may be reduced to increase the gas flow conductance in some regions and / or increased to decrease the gas flow conductance in other regions.

[0056] In some embodiments, the wall thickness (T) of the upper cavity 327 and / or the lower cavity 329 can be in the range of approximately 20-80 mm. In one preferred embodiment, the wall thickness (T) of the upper cavity 327 and / or the lower cavity 329 is primarily in the range of approximately 40-50 mm. In one exemplary implementation of such an embodiment, T1 can be 44.0 mm, T2 can be 41.3 mm, T3 can be 42.5 mm, T4 can be 43.7 mm, and T5 can be 78 mm. Although the wall thickness (T5) is wider at the distal end (i.e., the end of the purge block 328 closest to the outer edge of the platen 310), the gas flow conductance can be greater in this region due to its proximity to the gas outlet pumping port 340 (see FIGS. 3 and 4).

[0057] Other dimensions of the purge block 328 may also be selected based on the ALD system design and operating parameters. In some embodiments, for example, the gap (G) between the top of the purge block 328 and the chamber lid 380 may be smaller (e.g., about 1 mm) than the gap (e.g., about 3 mm) between the bottom of the purge block 328 and the susceptor 312. Because the gap (G) above the purge block 328 is smaller than the gap below the purge block, the gas flow from the second purge gas injector 370 (e.g., 1 standard liter per minute (slm)) may be less than the gas flow from the first purge gas injector 350 (e.g., 5-10 slm). The gas flow delivered to the upper cavity 327 may be smaller than the gas flow volume (V) delivered to the lower cavity 329. L ) smaller than U ), the depth of upper cavity 327 can be less than the depth of lower cavity 329 without affecting gas flow conductance. In one exemplary embodiment, the depth of upper cavity 327 can be 5 mm and the depth of lower cavity 329 can be 16 mm. Other depths and dimensions can be selected based on the design and operating parameters of the ALD system.

[0058] Figure 8 illustrates one embodiment of an exemplary method using the techniques described herein. It will be appreciated that the embodiment illustrated in Figure 8 is merely exemplary, and that additional methods may utilize the techniques described herein. Furthermore, the steps described are not intended to be exclusive, and additional processing steps may be added to the method illustrated in Figure 8. Furthermore, the order of the steps is not limited to the order shown in the figure, as different orders may occur and / or various steps may be combined or performed simultaneously.

[0059] FIG. 8 illustrates an embodiment method 400 for processing a substrate in a spatial atomic layer deposition (ALD) system. As described above and illustrated in FIGS. 3-7 , a spatial ALD system may generally include a platen and a purge block disposed above the platen to provide a purge gas to a processing space above the substrate. As illustrated in FIG. 8 , the method 400 may include providing a substrate on the platen in step 410. In step 420, the method 400 may include sequentially exposing the substrate to a first process gas and a second process gas as the platen rotates about a central axis of the spatial ALD system. In step 430, the method 400 may include injecting a purge gas into a lower cavity formed below the purge block after exposing the substrate to the first process gas and before exposing the substrate to the second process gas. In step 440, the method 400 may include distributing a purge gas within the lower cavity to prevent the first process gas and the second process gas from mixing within the process space, thereby causing the purge gas to flow evenly along the side edges of the purge block in a direction perpendicular to the side edges of the purge block.

[0060] Further modifications and alternative embodiments of the present invention will be apparent to those skilled in the art in view of the description herein. Accordingly, the description herein is to be construed as illustrative only and is for the purpose of teaching those skilled in the art how to carry out the invention. It is understood that the forms and methods of the present invention shown and described herein are to be taken as presently preferred embodiments. Equivalent techniques may be substituted for those illustrated and described herein, and certain features of the present invention may be utilized independently of the use of other features, all of which will become apparent to those skilled in the art after having the benefit of the description herein of the invention. [Explanation of symbols]

[0061] 100, 300 Substrate Processing Tools 105, 305 Processing chamber 110, 310 platen 112, 312 susceptor 115, 315 board 120, 320 First shower head 125, 325 Second shower head 128, 328 Purge Block 130, 340 Gas outlet pumping port 200 Mechanical Barrier 210 Purge Gas Injector 220 Conduction Path Ports 230 and 355 240, 360 processing space 250, 370 Second purge gas injector 260, 380 Chamber lid 326 Pass-Through 327 Upper cavity 329 Lower Cavity 330 side edge 350 First Purge Gas Injector

Claims

1. 1. A spatial atomic layer deposition (spatial ALD) system comprising: a platen for carrying one or more substrates, the platen configured to rotate 360° around a central axis of the spatial ALD system; a first showerhead disposed above the platen to provide a first process gas to the one or more substrates as the platen rotates; a purge block positioned above the platen for providing a purge gas to the one or more substrates after the first process gas has been provided to the one or more substrates; a lower cavity formed below the purge block; a first purge gas injector disposed within the lower cavity for injecting the purge gas below the purge block, the lower cavity configured to provide a lower gas conduction path for distributing the purge gas below the purge block; and an upper cavity formed above the purge block; a purge block including: a second purge gas injector for injecting a second purge gas onto the purge block, the upper cavity configured to provide an upper gas conduction path for distributing the second purge gas onto the purge block; and Equipped with the lower gas conduction path is configured to allow the purge gas to flow uniformly along a side edge of the purge block in a direction perpendicular to the side edge of the purge block; The upper gas conduction path is configured to allow the purge gas to flow evenly along a side edge of the purge block in a direction perpendicular to the side edge of the purge block.

2. 2. The spatial ALD system of claim 1, wherein the contour of the lower cavity is smaller than the contour of the purge block, thereby providing a uniform wall thickness along a majority of the purge block, the uniform wall thickness being measured between a side edge of the lower cavity and the side edge of the purge block.

3. The spatial ALD system of claim 2 , wherein the uniform wall thickness is selected from the range of 20 mm to 80 mm.

4. 3. The spatial ALD system of claim 2, wherein a wall thickness in one or more regions of the purge block is different from a wall thickness in other regions of the purge block to vary the gas flow conductance provided within the lower cavity in the one or more regions of the purge block.

5. 2. The spatial ALD system of claim 1, wherein a contour of the upper cavity is smaller than a contour of the purge block, thereby providing a uniform wall thickness along a majority of the purge block, the uniform wall thickness being measured between the upper gas conduction path provided in the upper cavity and the side edge of the purge block.

6. The spatial ALD system of claim 5, wherein the uniform wall thickness is selected from the range of 20 mm to 80 mm.

7. 6. The spatial ALD system of claim 5, wherein a wall thickness in one or more regions of the purge block is different from a wall thickness in other regions of the purge block to vary the gas flow conductance provided within the upper cavity in the one or more regions of the purge block.

8. 2. The spatial ALD system of claim 1, wherein a width of the purge block covers a portion of the 360° rotation of the platen, the portion being selected from a range including 10° to 40° of the 360° rotation of the platen.

9. 9. The spatial ALD system of claim 8, wherein the width of the purge block covers 20 degrees of the 360 ​​degree rotation of the platen.

10. 9. The spatial ALD system of claim 8, wherein the width of the purge block covers 30° of the 360° rotation of the platen.

11. a second showerhead disposed above the platen for providing a second process gas to the one or more substrates as the platen rotates; a further purge block disposed above the platen for providing the purge gas to the one or more substrates after the second process gas has been provided to the one or more substrates by the second showerhead, the first showerhead being larger than the second showerhead; and The spatial ALD system of claim 1 further comprising:

12. The depth of the lower cavity is greater than the depth of the upper cavity. The spatial ALD system of claim 1 .

13. The volume of the lower cavity is greater than the volume of the upper cavity. The spatial ALD system of claim 1 .

14. 1. A spatial atomic layer deposition (spatial ALD) system comprising: a platen for carrying one or more substrates, the platen configured to rotate 360° around a central axis of the spatial ALD system; a first showerhead disposed above the platen to provide a first process gas to the one or more substrates as the platen rotates; a purge block disposed above the platen for providing a purge gas to the one or more substrates after the first process gas has been provided to the one or more substrates; The purge block comprises: a lower cavity formed below the purge block and having a first volume; a first purge gas injector disposed within the lower cavity for injecting the purge gas below the purge block, the lower cavity configured to provide a lower gas conduction path for distributing the purge gas below the purge block; and an upper cavity formed above the purge block, the upper cavity having a second volume smaller than the first volume; a second purge gas injector for injecting a second purge gas onto the purge block, the upper cavity being configured to provide an upper gas conduction path for distributing the second purge gas onto the purge block; the lower gas conduction path is configured to allow the purge gas to flow uniformly along a side edge of the purge block in a direction perpendicular to the side edge of the purge block; the upper gas conduction path is configured so that the purge gas flows uniformly along the side edge of the purge block in a direction perpendicular to the side edge of the purge block. Spatial ALD system.

15. further comprising a chamber lid, wherein a gap exists between the chamber lid and the upper side of the purge block. The spatial ALD system of claim 14.

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