Dry etching system, dry etching method, and method for manufacturing semiconductor structure

Abstract

The application relates to a dry etching system, a dry etching method and a preparation method of a semiconductor structure. The dry etching system comprises an etching cavity, a carrier, a rotating device and a rotating flow module. The etching cavity is provided with an air inlet at the top and an air outlet at the bottom. The carrier is arranged in the etching cavity and used for carrying a wafer. The air outlet is arranged on the side of the carrier. The rotating device is arranged in the etching cavity and used for driving the carrier to rotate. The rotating flow module is arranged in the etching cavity and on the side of the carrier close to the air inlet, and is used for making the gas above the carrier rotate and fall, and making the rotating speed of the gas substantially consistent with the rotating speed of the carrier. The application can improve etching uniformity.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to a dry etching system, a dry etching method, and a method for preparing semiconductor structures. Background Technology

[0002] Dry etching is a common process in semiconductor manufacturing. During dry etching, the wafer is typically placed on a stage within an etching chamber. Process gas is then introduced through the chamber's inlet and extracted through its outlet, allowing the process gas to etch the wafer.

[0003] However, in some existing dry etching systems (such as some chemical dry etching systems), the vent is located on the side of the wafer stage, which results in a slower etching rate near the vent on the wafer (vent effect), thus affecting etching uniformity. Summary of the Invention

[0004] Therefore, it is necessary to provide a dry etching system, a dry etching method, and a method for fabricating semiconductor structures that can improve etching uniformity in response to the above-mentioned technical problems.

[0005] A dry etching system, comprising:

[0006] An etching cavity, wherein the top of the etching cavity has an air inlet and the bottom of the etching cavity has an air outlet;

[0007] A stage, located within the etching cavity, is used to support the wafer, and the vent is located to the side of the stage;

[0008] A rotating device, located inside the etching cavity, is used to drive the stage to rotate;

[0009] A swirl module, located within the etching cavity and on the side of the stage near the air inlet, is used to cause the gas directly above the stage to rotate and fall, and to ensure that the rotation speed of the gas is substantially the same as the rotation speed of the stage.

[0010] In one embodiment, the air extraction port is located in the central region of the etching cavity, the dry etching system includes at least two stages located on different sides of the air extraction port, and the vortex module includes at least two vortex units, which are arranged in a one-to-one correspondence with the stages.

[0011] In one embodiment, the dry etching system has a first region and a second region, the first region surrounding the second region, the vent located in the second region, and the edge of the stage intersecting the second region;

[0012] The swirling unit includes a first subunit and a second subunit. The first subunit is located in the first region, and the second subunit is located in the second region. The first subunit and the second subunit are used to provide different falling velocities for the gas.

[0013] In one embodiment, the dry etching system further includes a spray device located within the etching chamber and between the air inlet and the stage. The spray device has a housing with spray holes on the side of the housing facing the stage.

[0014] The swirl module is located inside the housing.

[0015] In one embodiment, the dry etching system includes at least two stages, and the swirl module includes at least two swirl units, each corresponding to one of the stages.

[0016] The swirl module also includes a partition, which is located between the swirl units.

[0017] In one embodiment, the rotating device includes a support rod and a driving device, the support rod being used to support the platform, and the driving device being used to drive the support rod to rotate, thereby causing the platform to rotate.

[0018] The dry etching system also includes a support device located within the etching cavity. The support device is located on the side of the support rod near the air extraction port and is used to support the support rod. The support device has a storage cavity inside, and the drive device is located inside the storage cavity.

[0019] A dry etching method, applied to the aforementioned dry etching system, includes:

[0020] The wafer is placed on the stage within the etching cavity;

[0021] The stage is controlled to rotate, inert gas is introduced into the etching cavity, and the swirl module is started to enter the stabilization stage. In the stabilization stage, the dry etching system gradually reaches a stable state. In the stable state, the rotation speed of the inert gas directly above the wafer is basically the same as the rotation speed of the stage.

[0022] Remove the inert gas from the etching cavity;

[0023] Process gas is introduced into the etching chamber to initiate the etching stage for etching the wafer; during the etching stage, the rotation speed of the process gas directly above the wafer is substantially the same as the rotation speed of the stage.

[0024] In one embodiment, before introducing inert gas into the etching cavity and activating the swirling module, the method further includes:

[0025] Obtain a first function and / or a second function; the first function is a function of a first speed difference with respect to a first time during the stabilization phase, the first speed difference being the absolute value of the difference between the rotational speed of the inert gas and the rotational speed of the stage; the second function is a function of a second speed difference with respect to a second time during the etching phase, the second speed difference being the difference between the falling speed of the process gas toward the wafer and the speed at which the process gas is extracted from the extraction port;

[0026] The vortex module is adjusted according to the first function and / or the second function.

[0027] A method for fabricating a semiconductor structure, comprising:

[0028] A substrate is provided, wherein a first device region and a second device region are provided on the substrate, and the first device region and the second device region are used to form devices of different conductivity types;

[0029] A gate dielectric material layer, a work function adjustment material layer, and a gate electrode material layer are sequentially formed on the substrate; the gate dielectric material layer and the gate electrode material layer are located in the first device region and the second device region, and the work function adjustment material layer is located in the first device region;

[0030] The gate electrode material layer is subjected to a first dry etching process to form a gate electrode layer; the gate electrode layer includes a first gate electrode and a second gate electrode, the first gate electrode being located in the first device region and the second gate electrode being located in the second device region;

[0031] The structure after the first dry etching is then subjected to a first wet cleaning process.

[0032] Using the dry etching system or the dry etching method described above, chemical dry etching is performed on the work function regulating material layer to form a work function regulating layer in the first device region;

[0033] The structure after the chemical dry etching is then subjected to a second wet cleaning process.

[0034] In one embodiment, the gate dielectric material layer includes an interface buffer layer and a high dielectric constant material layer sequentially formed on the substrate.

[0035] After performing a second wet cleaning on the structure following the chemical dry etching, the process further includes:

[0036] A second dry etching process is used to form the high dielectric constant material layer to form a high dielectric constant layer; the high dielectric constant layer includes a first high dielectric constant portion and a second high dielectric constant portion; the first high dielectric constant portion is located in the first device region, and the second high dielectric constant portion is located in the second device region.

[0037] The aforementioned dry etching system includes a rotating device and a swirl module. The rotating device drives the stage to rotate. Therefore, during the dry etching process on the wafer on the stage, the rotating device rotates the stage, thereby rotating the wafer. At this time, all edges of the wafer rotate to positions closer to the gas extraction port, ensuring a consistent etching rate across all edges and improving etching uniformity. Simultaneously, the swirl module ensures that the rotation speed of the process gas is essentially the same as the rotation speed of the stage during dry etching. This allows the process gas to remain relatively stationary or nearly stationary relative to the stage in the rotational direction, preventing horizontal slippage during etching and ensuring etching reliability. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a cross-sectional schematic diagram of a dry etching system in one embodiment;

[0040] Figure 2 This is a top view of a partial structure of a dry etching system in one embodiment;

[0041] Figure 3 This is a flowchart illustrating a dry etching method in one embodiment;

[0042] Figure 4 A schematic diagram of the function curve of a first function;

[0043] Figure 5 A schematic diagram of the function curve of a second function;

[0044] Figure 6 This is a schematic flowchart of a method for fabricating a semiconductor structure in one embodiment;

[0045] Figure 7 This is a schematic diagram of the cross-sectional structure after patterning the photoresist in one embodiment;

[0046] Figure 8 This is a schematic diagram of the cross-sectional structure after etching the conductive material layer in one embodiment;

[0047] Figure 9 This is a schematic diagram of the cross-sectional structure after etching the metal barrier material layer in one embodiment;

[0048] Figure 10 This is a schematic cross-sectional structure diagram of the work function-adjustable material layer at the start of chemical dry etching in one embodiment;

[0049] Figure 11 This is a schematic diagram of the cross-sectional structure of a work function-adjustable material layer after chemical dry etching in one embodiment.

[0050] Figure 12 This is a schematic diagram of the cross-sectional structure after etching a high dielectric constant material layer in one embodiment;

[0051] Among them, Figures 7 to 12 In the diagram, (a) is a schematic diagram of the cross-sectional structure of the first device region, and (b) is a schematic diagram of the cross-sectional structure of the second device region.

[0052] Explanation of reference numerals in the attached figures:

[0053] 100 - Etching cavity, 110 - Air inlet, 120 - Air outlet, 200 - Stage, 300 - Rotation device, 310 - Support rod, 320 - Drive device, 400 - Swirl module, 401 - Swirl generator, 410 - Swirl unit, 411 - First sub-unit, 412 - Second sub-unit, 510 - Air inlet pipe, 520 - Air outlet pipe, 600 - Air pump, 700 - Spray device, 710 - Spray hole, A11 - First region, A12 - Second region, 10 - Substrate, A21 - First device region, A22 - Second device region, 20a - Gate dielectric Material layer, 20-gate dielectric layer, 21-interface buffer layer, 22a-high dielectric constant material layer, 22-high dielectric constant layer, 30a-work function adjustment material layer, 30-work function adjustment layer, 40a-gate electrode material layer, 41a-metal diffusion barrier material layer, 42a-conductive material layer, 40-gate electrode layer, 41-metal diffusion barrier layer, 42-conductive layer, 50a-mask material layer, 51a-first mask sub-material layer, 52a-second mask sub-material layer, 50-mask layer, 51-first mask sub-layer, 52-second mask sub-layer, 60-patterned photoresist. Detailed Implementation

[0054] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0056] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.

[0057] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as “below,” “under,” or “below” will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0058] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediary element. Furthermore, in the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if there is transmission of electrical signals or data between the connected objects.

[0059] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0060] The dry etching system and dry etching method in the embodiments of this application can be applied to, but are not limited to, chemical dry etching, and can also be applied to plasma dry etching, for example.

[0061] In one embodiment, see Figure 1 A dry etching system is provided, including an etching cavity 100, a stage 200, a rotating device 300, and a swirl module 400.

[0062] The top of the etching chamber 100 has an air inlet 110. The air inlet 110 is connected to an external air intake pipe 510, so that gas in the air intake pipe 510 can enter the etching chamber 100.

[0063] The bottom of the etching chamber 100 has an exhaust port 120. The exhaust port 120 can be connected to an external exhaust pipe 520. At the same time, the other end of the exhaust pipe 520 can be connected to an exhaust pump 600, so that the gas inside the etching chamber 100 can be extracted by the exhaust pump 600.

[0064] The stage 200 is located inside the etching cavity 100 and is used to support the wafer. The vent 120 is located on one side of the stage 200.

[0065] The rotating device 300 is also located inside the etching cavity 100 and is used to drive the stage 200 to rotate.

[0066] The swirling module 400 is located within the etching cavity 100 and on the stage 200 near the air inlet 110. Exemplarily, the swirling module 400 may include a plurality of swirlers 401.

[0067] The swirl module 400 can act as a swirl, causing the gas directly above the stage 200 to rotate and fall.

[0068] Specifically, under the action of the rotating module, the gas directly above the stage 200 can rotate around or nearly around the stage 200 in a circumferential direction. At the same time, the gas directly above the stage 200 also has a falling speed toward the wafer on the stage 200.

[0069] Meanwhile, the swirl module 400 can make the rotation speed of the gas directly above the stage 200 basically the same as the rotation speed of the stage 200.

[0070] Specifically, "the rotational speed of the gas is basically the same as the rotational speed of the stage 200" can be understood as: the difference between the rotational speed of the gas and the rotational speed of the stage 200 is dn, and the absolute value of dn is less than or equal to a preset value. The preset value can be set according to actual needs. For example, the preset value can be 6 r / min to 7 r / min.

[0071] For example, the preset value is 5 r / min. If the absolute value of dn is less than or equal to the preset value of 5 r / min, it can be considered that the rotational speed of the gas is basically the same as the rotational speed of the stage 200.

[0072] In this embodiment, the dry etching system includes a rotating device 300 and a swirl module 400. The rotating device 300 can drive the stage 200 to rotate. Therefore, during the dry etching process on the wafer on the stage 200, the rotating device 300 can rotate the stage 200, thereby causing the wafer to rotate. At this time, the edges of the wafer in all directions will rotate to a position close to the gas extraction port 120, so the etching rate of all edges of the wafer can be consistent, thereby improving etching uniformity. At the same time, through the setting of the swirl module 400, the rotation speed of the process gas during the dry etching process of the wafer can be basically consistent with the rotation speed of the stage 200. At this time, the process gas can reach relative stillness or near stillness with the stage 200 in the rotation direction, so that the process gas will not slip horizontally when etching the wafer on the stage 200, thereby ensuring etching reliability.

[0073] In one embodiment, see Figure 1 The vent 120 is located in the central region of the etching chamber 100. The dry etching system includes at least two stages 200 located on different sides of the vent 120. Therefore, for each stage 200, the vent 120 is located to its side.

[0074] Please also refer to Figure 2 as well as Figure 1 The swirl module 400 includes at least two swirl units 410. Exemplarily, each swirl unit 410 may include a plurality of swirlers 401.

[0075] The swirl units 410 are configured in a one-to-one correspondence with the stages 200. That is, a corresponding swirl unit 410 can be set directly above each stage 200. In this case, during the dry etching process, the process gas directly above each stage 200 can rotate and fall under the action of the corresponding swirl unit 410, and the rotation speed of the process gas directly above each stage 200 can be basically consistent with its own rotation speed. This allows the wafers on each stage 200 to be effectively etched by the process gas, which has no relative rotation speed with the wafer.

[0076] For example, the dry etching system includes two stages 200. The two stages 200 are located on opposite sides of the exhaust port 120. Meanwhile, the vortex module 400 includes two vortex units 410. One vortex unit 410 is disposed directly above each stage 200. The two vortex units 410 are also located on opposite sides of the exhaust port 120.

[0077] Of course, the number and arrangement of the stage 200 and the swirl unit 410 are not limited to this. For example, the etching cavity 100 may also have three or more stages 200 arranged around the exhaust port 120. Correspondingly, the swirl module 400 may include three or more swirl units 410 arranged around the exhaust port 120.

[0078] In this embodiment, the dry etching system can etch at least two wafers simultaneously, thereby effectively improving etching efficiency.

[0079] In one embodiment, please also refer to Figure 2 as well as Figure 1 The dry etching system has a first region A11 and a second region A12. The first region A11 surrounds the second region A12. The vent 120 is located in the second region A12. The edge of the stage 200 intersects with the second region A12. Specifically, on a horizontal projection plane, the orthographic projection of the stage 200 can intersect with the orthographic projection of the second region A12, and the orthographic projection of the center of the stage 200 can be located outside the orthographic projection of the second region A12.

[0080] The swirl unit 410 includes a first subunit 411 and a second subunit 412. It can be understood that when the dry etching system includes at least two stages 200 and the swirl module 400 includes at least two swirl units 410, each swirl unit 410 includes a first subunit 411 and a second subunit 412.

[0081] The first subunit 411 is located in the first region A11. The second subunit 412 is located in the second region A12.

[0082] The first subunit 411 and the second subunit 412 are used to provide different falling speeds for the gas.

[0083] In actual wafer etching processes, in addition to the vent 120 effect, uneven etching between the edge and the center sometimes occurs. In this case, by configuring the first sub-unit 411 and the second sub-unit 412, the process gas can be made to fall at different speeds at the wafer center and edge, thereby compensating for the uneven etching between the wafer center and edge and improving the etching uniformity of the entire wafer.

[0084] For example, when etching a wafer using a conventional dry etching system, the etching rate at the edges is greater than that at the center, resulting in a thinner edge thickness than the center thickness after etching. However, under the same etching conditions, when etching a wafer using the dry etching system of this embodiment, the falling speed of the gas provided by the second subunit 412 can be set to be less than the falling speed of the gas provided by the first subunit 411, thereby reducing the etching rate at the wafer edges and improving the etching uniformity of the entire wafer.

[0085] Of course, the relative magnitudes of the gas drop speeds provided by the first subunit 411 and the second subunit 412 can be adjusted according to actual conditions. For example, when etching a wafer using a conventional dry etching system, if the etching rate at the edge is less than that at the center, the drop speed provided by the second subunit 412 can be set to be greater than that provided by the first subunit 411, thereby increasing the etching rate at the wafer edge.

[0086] In one embodiment, see Figure 1 The dry etching system also includes a spray device 700. The spray device 700 is located inside the etching chamber 100 and between the air inlet 110 and the stage 200. The spray device 700 has a housing, and spray holes 710 are provided on the side of the housing facing the stage 200.

[0087] The gas entering the etching chamber 100 through the air inlet 110 can first enter the housing of the spray device 700. Then, it flows from the spray holes 710 of the housing to the wafer.

[0088] The swirl module 400 is located within the housing, thereby effectively swirling the gas before it flows to the wafer. Simultaneously, placing the swirl module 400 within the housing of the spray device 700 reduces the structural complexity of the dry etching system.

[0089] For example, the dry etching system includes at least two stages 200, and the swirl module 400 includes at least two swirl units 410, with each swirl unit 410 corresponding to one of the stages 200.

[0090] Meanwhile, the swirl module 400 also includes a baffle plate located between the swirl units 410. Specifically, for example, the swirl module 400 includes two swirl units 410 arranged opposite each other. Then a baffle plate can be provided between the two swirl units 410. As another example, the swirl module 400 includes three or more swirl units 410. Then a baffle plate can be provided between every two adjacent swirl units 410.

[0091] At this time, mutual interference between the swirling units 410 can be prevented, and interference caused by the flow of gas directly above each swirling unit 410 and other non-opposite stage 200 can be prevented, thereby ensuring the swirling effect of each swirling unit 410.

[0092] Of course, when the distance between the swirl units 410 is large enough, baffles may not be necessary. Baffles can also be installed according to actual needs.

[0093] In one embodiment, see Figure 1 The rotating device 300 includes a support rod 310 and a driving device 320.

[0094] The support rod 310 supports the stage 200. The drive device 320 drives the support rod 310 to rotate, thereby causing the stage 200 to rotate. Exemplarily, the drive device 320 includes a motor and a gear. The motor can drive the gear to rotate, and the rotation of the gear can drive the support rod 310 to rotate, thereby causing the stage 200 to rotate.

[0095] The dry etching system also includes a support device located within the etching chamber 100. The support device is located on the side of the support rod 310 near the air extraction port 120 and is used to support the support rod 310. The support device has a receiving cavity inside, and the drive device 320 is located inside the receiving cavity.

[0096] In traditional dry etching systems, the support device directly supports the stage 200. In this embodiment, for example, a cavity for housing the drive device 320 can be provided within the conventional support device, and a support rod 310 can be placed on the support device, thereby enabling the rotation function of the stage 200 in a simple and effective manner.

[0097] In one embodiment, see Figure 3 Furthermore, a dry etching method is provided, which can be applied to any of the above-mentioned dry etching systems.

[0098] The dry etching method includes the following steps:

[0099] Step S100: Place the wafer on the stage 200 inside the etching cavity 100;

[0100] In step S200, the stage 200 is rotated, inert gas is introduced into the etching cavity 100, and the vortex module 400 is started to enter the stabilization stage. In the stabilization stage, the dry etching system gradually reaches a stable state. In the stable state, the rotation speed of the inert gas above the wafer is basically the same as the rotation speed of the stage 200.

[0101] Step S300: Remove the inert gas from the etching cavity 100;

[0102] In step S400, process gas is introduced into the etching chamber 100 to enter the etching stage for etching the wafer; during the etching stage, the rotation speed of the process gas above the wafer is basically the same as the rotation speed of the stage 200.

[0103] In step S100, a robotic arm can be used to transfer the wafer into the etching chamber 100 and place it on the stage 200. For example, the stage 200 can fix the wafer using methods such as vacuum adsorption.

[0104] Step S200 may specifically include: step S210 controlling the stage 200 to rotate; step S220 introducing inert gas into the etching cavity 100; and step S230 activating the vortex module 400.

[0105] In step S210, the rotating device 300 can be controlled, thereby controlling the rotation of the stage 200. For example, the rotating device 300 includes a motor, gears, and a support rod 310. By energizing the motor, the gears are driven to rotate, which in turn drives the support rod 310 to rotate, thereby causing the stage 200 to rotate, and consequently, the wafer placed on the stage 200 rotates accordingly.

[0106] Furthermore, the execution order of steps S210, S220, and S230 is not fixed and can be adjusted according to actual needs. Alternatively, steps S210, S220, and S230 can be executed simultaneously, either partially or entirely; no restrictions are placed on this.

[0107] After steps S210, S220, and S230 are completed, the system enters a stable phase, and the dry etching system gradually reaches a stable state. During this process, the inert gas directly above the wafer is rotated by the swirling effect of the swirling module 400. Furthermore, the rotational speed of the inert gas directly above the wafer gradually changes from being different from the rotational speed of the stage 200 to being essentially the same as the rotational speed of the stage 200.

[0108] It should be noted that during the steady-state phase, there are no restrictions on the vertical movement of the inert gas; it may or may not have a falling velocity.

[0109] In step S300, the inert gas inside the etching chamber 100 can be removed by evacuation. During this process, the state of the vortex module 400 can remain unchanged, thereby maintaining a stable state.

[0110] In step S400, the process gas introduced into the etching chamber 100 may include an etching gas. The etching gas can react with the material on the wafer, thereby etching the wafer.

[0111] For example, the process gas may also include a dilution gas. The dilution gas may not participate in the reaction. The relative atomic mass of the dilution gas may be similar to that of the etching gas, thereby achieving the principle of like dissolves like.

[0112] Meanwhile, the etching stage is carried out after the dry etching system has reached a stable state. Therefore, during the etching stage, the rotation speed of the process gas directly above the wafer can always be basically consistent with the rotation speed of the stage 200, thus ensuring a good etching effect.

[0113] Simultaneously, during the etching stage, it's crucial to ensure the process gas directly above the wafer maintains a falling velocity, allowing it to reach the wafer surface and etch it. In actual processes, the rotation of the process gas by the swirl module 400 may affect the angle of the extraction valve to maintain constant pressure. Changes in the extraction valve angle can influence the falling velocity of the process gas. Therefore, during the etching stage, the falling velocity of the process gas above the wafer can be monitored in real-time. Based on the monitoring results, the swirl module 400 can be adjusted. If the falling velocity is insufficient, the swirl module 400 can be used to increase it, ensuring the process gas reaches the wafer surface for etching. It's important to understand that adjusting the swirl module 400 only adjusts its vertical function; its rotational function remains unchanged, ensuring the rotational speed of the process gas above the wafer is essentially the same as the rotational speed of the stage 200.

[0114] In one embodiment, after step S400, the method further includes:

[0115] Step S310: Obtain the first function f(t1) and / or the second function f(t2); the first function f(t1) is a function of the first velocity difference with respect to the first time t1 during the stabilization phase, and the first velocity difference is the absolute value of the difference between the rotational speed of the inert gas and the rotational speed of the stage 200; the second function f(t2) is a function of the second velocity difference with respect to the second time t2 during the etching phase, and the second velocity difference is the difference between the falling speed of the process gas toward the wafer and the speed at which the process gas is extracted from the extraction port 120;

[0116] Step S320: Adjust the vortex module 400 according to the first function f(t1) and / or the second function f(t2).

[0117] The first function f(t1) and / or the second function f(t2) can be functions obtained by fitting data within a preset time period. For example, the first function f(t1) and / or the second function f(t2) can be functions obtained by fitting data within a six-month period prior to the function fitting.

[0118] Please refer to Figure 4 The first function f(t1) is a function of the first velocity difference with respect to the first time t1 during the steady-state phase. It should be noted that... Figure 4 This is just an illustration; the shape and variation of the function curve in the actual process may differ from this.

[0119] The first speed difference is the absolute value of the difference between the rotational speed of the inert gas directly above the wafer and the rotational speed of the stage 200.

[0120] For example, the first velocity difference within the stable phase of the aforementioned preset time period can be fitted to the first time t1 using function fitting methods such as the least squares method, thereby obtaining the first function f(t1).

[0121] Theoretically, the first function f(t1) should reach a stable state in its later stages, with the value of f(t1) (the first velocity difference) remaining stably around a fixed value. This fixed value can be less than or equal to the preset value described earlier (e.g., 5 r / min). If the value of the first function f(t1) obtained in step S310 does not meet the ideal theoretical requirement (it does not remain stably around a fixed value in its later stages, i.e., it does not reach a stable state), then step S320 can adjust the vortex module 400 based on this first function f(t1). Of course, if the value of the first function f(t1) obtained in step S310 meets the ideal theoretical requirement, then step S320 keeps the settings of the vortex module 400 unchanged.

[0122] Please see Figure 5 The second function f(t2) is a function of the second velocity difference with respect to the second time t2 during the etching stage. It should be noted that... Figure 5 This is just an illustration; the shape and variation of the function curve in the actual process may differ from this.

[0123] The second velocity difference is the difference between the falling velocity of the process gas directly above the wafer and the velocity of the process gas as it is extracted from the extraction port 120. In other words, the second velocity difference is equal to the falling velocity of the process gas towards the wafer minus the velocity of the process gas as it is extracted from the extraction port 120.

[0124] For example, the second velocity difference within the etching stage during the aforementioned preset time period can be fitted to the second time t2 using function fitting methods such as the least squares method, thereby obtaining the second function f(t2).

[0125] The value of the second function f(t2) (the second velocity difference) should theoretically be greater than 0.

[0126] If the value of the second function f(t2) obtained in step S310 does not meet the ideal theoretical requirements (none of which is greater than 0), then step S320 can adjust the vortex module 400 based on the second function f(t2). Of course, if the value of the second function f(t2) obtained in step S320 meets the ideal theoretical requirements, then step S320 keeps the settings of the vortex module 400 unchanged.

[0127] For example, the swirling unit 410 includes a first subunit 411 and a second subunit 412. The first subunit 411 is located in a first region A11, and the second subunit 412 is located in a second region A12. The first subunit 411 and the second subunit 412 are used to provide different falling velocities for the gas.

[0128] At this point, under the action of the same swirl unit 410, the second function f(t2) can include both the first sub-function and the second sub-function. The first sub-function is the second function f(t2) located within the first region A11. The second sub-function is the second function f(t2) located within the second region A12.

[0129] In this case, theoretically, the value of the first sub-function is different from the value of the second sub-function.

[0130] For example, if the falling speed provided by the first sub-unit 411 to the gas is greater than the falling speed provided by the second sub-unit 412 to the gas, theoretically the value of the first sub-function must always be greater than the value of the second sub-function.

[0131] At this point, if the values ​​of the first sub-function and the second sub-function obtained in step S310 do not meet the ideal theoretical requirements (for example, the value of the first sub-function is not consistently greater than the value of the second sub-function), then step S320 can adjust the first sub-unit 411 and / or the second sub-unit 412 of the vortex unit 410 based on these first and second sub-functions. Of course, if the values ​​of the first and second sub-functions obtained in step S310 meet the ideal theoretical requirements, then step S320 keeps the settings of the vortex module 400 unchanged.

[0132] It should be understood that, although Figure 3 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 3At least some of the steps in the process may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but may be executed at different times. The execution order of these steps or stages is not necessarily sequential, but may be executed in turn or alternately with other steps or at least some of the steps or stages in other steps.

[0133] In one embodiment, see Figure 6 Furthermore, a method for fabricating a semiconductor structure is provided, comprising the following steps:

[0134] Step S10, please refer to Figure 7 A substrate 10 is provided, on which a first device region A21 and a second device region A22 are provided, and the first device region A21 and the second device region A22 are used to form devices of different conductivity types;

[0135] For step S20, please refer to... Figure 7 A gate dielectric material layer 20a, a work function adjustment material layer 30a, and a gate electrode material layer 40a are sequentially formed on a substrate 10; the gate dielectric material layer 20a and the gate electrode material layer 40a are located in the first device region A21 and the second device region A22, and the work function adjustment material layer 30a is located in the first device region A21.

[0136] For step S30, please refer to... Figure 9 The gate electrode material layer 40a is subjected to a first dry etching process to form the gate electrode layer 40. The gate electrode layer 40 includes a first gate electrode and a second gate electrode. The first gate electrode is located in the first device region A21, and the second gate electrode is located in the second device region A22.

[0137] Step S40: Perform a first wet cleaning on the structure after the first dry etching.

[0138] For step S50, please refer to... Figure 10 as well as Figure 11 Using any of the above-mentioned dry etching systems or dry etching methods, chemical dry etching is performed on the work function adjustment material layer 30a to form the work function adjustment layer 30 in the first device region A21.

[0139] Step S60: Perform a second wet cleaning on the structure after chemical dry etching.

[0140] In step S10, please refer to Figure 7 The substrate 10 is a semiconductor substrate 10, which may include, but is not limited to, a silicon substrate 10.

[0141] In step S20, please refer to Figure 7The gate dielectric material layer 20a, the work function adjustment material layer 30a, and the gate electrode material layer 40a may each include multiple film layers or a single film layer, depending on actual needs. Here, "multiple" means two or more.

[0142] The work function adjusting material layer 30a can be made of materials including, but not limited to, lanthanum oxide. The work function adjusting material layer 30a is located in the first device region A21, but not in the second device region A22, allowing the first device region A21 and the second device region A22 to form devices of different conductivity types. For example, the first device region A21 and the second device region A22 can form an NMOS, and the second device region A22 can form a PMOS.

[0143] In step S30, please refer to Figure 7 First, a mask material layer 50a and a patterned photoresist 60 can be sequentially formed on the gate electrode material layer 40a. Then, based on the patterned photoresist 60, the mask material layer 50a can be etched to form the patterned mask layer 50. Then, please refer to... Figure 9 The gate electrode material layer 40a is etched based on the patterned mask layer 50 to form the gate electrode layer 40. The patterned photoresist 60 can then be removed. Exemplarily, the mask material layer 50a may include a first mask sub-material layer 51a and a second mask sub-material layer 52a. Correspondingly, the mask layer 50 may include a first mask sub-layer 51 and a second mask sub-layer 52.

[0144] The first dry etching of the gate electrode material layer 40a can be plasma dry etching, thereby forming the first gate electrode and the second gate electrode in the first device region A21 and the second device region A22, respectively.

[0145] For example, please refer to Figure 8 as well as Figure 9 The gate electrode material layer 40a includes a metal diffusion barrier material layer 41a and a conductive material layer 42a. During the first dry etching of the gate electrode material layer 40a, the conductive material layer 42a and the metal diffusion barrier material layer 41a can be etched sequentially. After etching, the remaining conductive material layer 42a forms the conductive layer 42, and the remaining metal diffusion barrier material layer 41a forms the metal diffusion barrier layer 41. The metal diffusion barrier layer 41 and the conductive layer 42 form the gate electrode layer 40. The material of the conductive layer 42 includes, but is not limited to, polysilicon. The material of the metal diffusion barrier layer 41 includes, but is not limited to, titanium nitride.

[0146] In step S40, etching byproducts such as polymers formed by the first dry etching can be removed by the first wet cleaning process.

[0147] In step S50, please refer to Figure 10 as well as Figure 11 When chemical dry etching is performed on the work function adjustment material layer 30a located in the first device region A21 using the dry etching system or dry etching method in the embodiments of this application, it can effectively prevent uneven etching caused by the evacuation port 120 effect, and at the same time effectively ensure good etching effect.

[0148] Meanwhile, when chemical dry etching is performed on the work function adjustment material layer 30a located in the first device region A21, the work function adjustment material layer 30a in the first device region A21 is not affected, and the chemical dry etching completely stops at the gate dielectric material layer 20a. This allows control over the etching degree of the second device region A22, effectively avoiding the problem of over-etching of the second device region A22 caused by the simple plasma dry etching method.

[0149] For example, the work function regulating material layer 30a is made of lanthanum oxide (La₂O₃). When performing chemical dry etching on the work function regulating material layer 30a located in the first device region A21, the process gases used may include HCl (etching gas) and Ar (dilution gas). Ar gas acts as a dilution gas and does not participate in the reaction; its relative atomic mass is similar to that of HCl, thus achieving like dissolves like. The reaction mechanism of HCl (etching gas) etching lanthanum oxide (La₂O₃) can be:

[0150] HCL(g)+La2O3(s)->LaCl3(s)+H2O(g).

[0151] In step S60, a second wet cleaning is performed on the structure after chemical dry etching to remove residues such as LaCl3(s) after chemical dry etching.

[0152] For example, the gate dielectric material layer 20a includes an interface buffer layer 21 and a high dielectric constant material layer 22a sequentially formed on the substrate 10. The interface buffer layer 21 may be made of silicon oxide or the like. The high dielectric constant material layer 22a may be made of hafnium oxysilicon (HfSION) or the like.

[0153] After step S60, the following is also included:

[0154] For step S70, please refer to... Figure 12 A second dry etching process is used to form a high dielectric constant material layer 22a to form a high dielectric constant layer 22. The high dielectric constant layer 22 includes a first high dielectric constant portion and a second high dielectric constant portion. The first high dielectric constant portion is located in the first device region A21, and the second high dielectric constant portion is located in the second device region A22.

[0155] The high dielectric constant layer 22 and the interface buffer layer 21 can form the gate dielectric layer 20.

[0156] At this time, during the semiconductor structure fabrication process, the first dry etching, the first wet cleaning, the chemical dry etching, the second wet cleaning, and the second dry etching are carried out in sequence, which effectively achieves the simultaneous formation of high-performance gate structures in both the first device region A21 and the second device region A22.

[0157] In the description of this specification, references to terms such as "one embodiment," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0158] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0159] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A dry etching system, characterized in that, include: An etching cavity, wherein the top of the etching cavity has an air inlet and the bottom of the etching cavity has an air outlet; A stage, located within the etching cavity, is used to support the wafer, and the vent is located to the side of the stage; A rotating device, located inside the etching cavity, is used to drive the stage to rotate; A swirl module, located within the etching cavity and on the side of the stage near the air inlet, is used to cause the gas directly above the stage to rotate and fall, and to make the rotation speed of the gas basically the same as the rotation speed of the stage; when the rotation speed of the gas is basically the same as the rotation speed of the stage, the gas reaches relative stillness or near relative stillness with the stage in the rotation direction.

2. The dry etching system according to claim 1, characterized in that, The air extraction port is located in the central region of the etching cavity. The dry etching system includes at least two stages located on different sides of the air extraction port. The vortex module includes at least two vortex units, and the vortex units are arranged in a one-to-one correspondence with the stages.

3. The dry etching system according to claim 2, characterized in that, The dry etching system has a first region and a second region, the first region surrounding the second region, the vent located in the second region, and the edge of the stage intersecting the second region; The swirling unit includes a first subunit and a second subunit. The first subunit is located in the first region, and the second subunit is located in the second region. The first subunit and the second subunit are used to provide different falling velocities for the gas.

4. The dry etching system according to claim 1, characterized in that, The dry etching system also includes a spray device located inside the etching chamber and between the air inlet and the stage. The spray device has a housing, and spray holes are provided on the side of the housing facing the stage. The swirl module is located inside the housing.

5. The dry etching system according to claim 4, characterized in that, The dry etching system includes at least two stages, and the swirl module includes at least two swirl units, with each swirl unit corresponding to one of the stages. The swirl module also includes a partition, which is located between the swirl units.

6. The dry etching system according to claim 1, characterized in that, The rotating device includes a support rod and a driving device. The support rod is used to support the platform, and the driving device is used to drive the support rod to rotate, thereby causing the platform to rotate. The dry etching system also includes a support device located within the etching cavity. The support device is located on the side of the support rod near the air extraction port and is used to support the support rod. The support device has a storage cavity inside, and the drive device is located inside the storage cavity.

7. A dry etching method, characterized in that, The dry etching system according to any one of claims 1-6 is characterized in that it comprises: The wafer is placed on the stage within the etching cavity; The stage is controlled to rotate, inert gas is introduced into the etching cavity, and the swirl module is started to enter the stabilization stage. In the stabilization stage, the dry etching system gradually reaches a stable state. In the stable state, the rotation speed of the inert gas directly above the wafer is basically the same as the rotation speed of the stage. Remove the inert gas from the etching cavity; Process gas is introduced into the etching chamber to initiate the etching stage for etching the wafer; during the etching stage, the rotation speed of the process gas directly above the wafer is substantially the same as the rotation speed of the stage.

8. The dry etching method according to claim 7, characterized in that, Before introducing inert gas into the etching cavity and activating the swirling module, the procedure further includes: Obtain a first function and / or a second function; the first function is a function of a first speed difference with respect to a first time during the stabilization phase, wherein the first speed difference is the absolute value of the difference between the rotational speed of the inert gas and the rotational speed of the stage; the second function is a function of a second speed difference with respect to a second time during the etching phase, wherein the second speed difference is the difference between the falling speed of the process gas toward the wafer and the speed at which the process gas is extracted from the extraction port; The vortex module is adjusted according to the first function and / or the second function.

9. A method for fabricating a semiconductor structure, characterized in that, include: A substrate is provided, wherein a first device region and a second device region are provided on the substrate, and the first device region and the second device region are used to form devices of different conductivity types; A gate dielectric material layer, a work function adjustment material layer, and a gate electrode material layer are sequentially formed on the substrate; The gate dielectric material layer and the gate electrode material layer are located in the first device region and the second device region, and the work function adjustment material layer is located in the first device region; The gate electrode material layer is subjected to a first dry etching process to form a gate electrode layer; the gate electrode layer includes a first gate electrode and a second gate electrode, the first gate electrode being located in the first device region and the second gate electrode being located in the second device region; The structure after the first dry etching is then subjected to a first wet cleaning process. Using the dry etching system according to any one of claims 1-6 or the dry etching method according to any one of claims 7-8, chemical dry etching is performed on the work function regulating material layer to form a work function regulating layer in the first device region; The structure after the chemical dry etching is then subjected to a second wet cleaning process.

10. The method for preparing a semiconductor structure according to claim 9, characterized in that, The gate dielectric material layer includes an interface buffer layer and a high dielectric constant material layer sequentially formed on the substrate. After performing a second wet cleaning on the structure following the chemical dry etching, the process further includes: A second dry etching process is used to form the high dielectric constant material layer to form a high dielectric constant layer; the high dielectric constant layer includes a first high dielectric constant portion and a second high dielectric constant portion; the first high dielectric constant portion is located in the first device region, and the second high dielectric constant portion is located in the second device region.

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