A process cavity with controllable gas flow field and plasma processing equipment

Abstract

This invention relates to the field of semiconductor manufacturing equipment technology, and more particularly to a process cavity and plasma processing equipment with controllable gas flow field. The cavity includes a cavity body having a chamber for supporting a wafer; an inlet channel communicating with the chamber; a main extraction channel located at the bottom of the cavity body and communicating with the chamber; the main extraction channel connected to a main control valve; a secondary extraction channel located on the side wall of the cavity body and communicating with the chamber; the main control valve and the secondary control valve working in concert; and a control device communicatively connected to the main control valve and the secondary control valve. This invention, through the coordination of the secondary extraction channel and the secondary control valve with the main extraction channel and the main control valve, adjusts the flow field distribution within the process cavity, guiding and eliminating the gas concentration gradient and edge dead zones in the radial direction of the wafer, thereby achieving consistency in the side angles of the outer perimeter trenches or holes, and the surface roughness of the central and edge regions of the wafer.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing equipment technology, and in particular to a process cavity with controllable gas flow field and plasma processing equipment. Background Technology

[0002] Existing inductively coupled plasma (ICP) etching equipment generally adopts a "top-center air intake + bottom-center single air extraction" structure, with the extraction rate adjusted via a bottom swing valve. This approach only allows for coarse overall pressure adjustment and cannot perform local fine-tuning of the radial flow field distribution on the wafer, resulting in:

[0003] (1) The gas forms a high-concentration central jet during vertical flow, resulting in a significantly higher process gas concentration in the central region of the wafer than in the edge region;

[0004] (2) Due to the movement characteristics of gas towards the low-pressure area, some process gas is drawn away by the bottom center exhaust port before it comes into contact with the wafer surface, forming a "dead zone" on the outer edge of the wafer.

[0005] In the existing technology, simply adjusting the pumping rate of the bottom swing valve cannot change the inherent concentration gradient of "high gas concentration in the central region and low gas concentration in the edge region", nor can it eliminate the edge dead zone caused by the fixed flow field path. As a result, the problem of inconsistent side angles of the outer ring trench / hole of the wafer and inconsistent surface roughness between the central and edge regions will still occur. Summary of the Invention

[0006] To achieve the above objectives, the present invention provides a process cavity with controllable gas flow field, comprising:

[0007] The cavity body has a chamber for holding the wafer;

[0008] An air intake channel, connected to the chamber, is used to introduce process gas into the chamber;

[0009] The main extraction channel is located at the bottom of the cavity body and communicates with the cavity; the main extraction channel is connected to the main control valve and is used to establish an extraction flow field of process gas along the axial direction of the wafer.

[0010] A secondary exhaust channel is located on the side wall of the cavity body and communicates with the cavity. The horizontal plane of the exhaust port of the secondary exhaust channel is located above the supported wafer. The secondary exhaust channel is connected to a corresponding secondary control valve to establish an exhaust gas flow field in the radial direction of the wafer. There are multiple secondary exhaust channels, and the exhaust ports of the multiple secondary exhaust channels are arranged in a ring structure on the side wall of the cavity body.

[0011] A control device, communicatively connected to the main control valve and the auxiliary control valve, is used to control the main control valve and the auxiliary control valve to work together to adjust the flow field distribution within the process chamber.

[0012] Optionally, there are multiple auxiliary air extraction channels, and the air extraction ports of the multiple auxiliary air extraction channels are arranged at the same height on the side wall of the cavity body to form a single-layer ring structure for establishing a single-layer radial air extraction field in the cavity body.

[0013] Optionally, there are multiple auxiliary extraction channels, which are arranged at at least two different heights on the sidewall of the cavity body to form at least two annular structures; each annular structure includes at least multiple auxiliary extraction channels to form at least two radial extraction airflow fields in the axial direction of the wafer.

[0014] Optionally, the number of secondary exhaust channels included in each layer of the annular structure is consistent, so as to form at least two identical radial exhaust airflow fields.

[0015] Optionally, the number of the secondary extraction channels included in two adjacent annular structures increases layer by layer from top to bottom along the axial direction of the wafer to form two distinct radial extraction flow fields.

[0016] Optionally, the distance between the lower edge of the vent and the upper surface of the wafer along the wafer axis is between 5 mm and 40 mm.

[0017] Optionally, the auxiliary air extraction channel is an independent channel structure, and the height of the channel cavity of the channel structure is between 1.5 mm and 4 mm.

[0018] Optionally, the auxiliary air extraction channel is an independent channel structure and has an L-shaped structure. The auxiliary air extraction channel includes a horizontal section and a vertical section. The horizontal section is used to connect the inner cavity of the cavity body and the vertical section.

[0019] The height of the transverse section's channel cavity is between 1.5mm and 4mm; the lower opening of the vertical section is located on the bottom wall of the cavity body and communicates with the secondary control valve, and the height of the vertical section's channel cavity is between 40mm and 80mm.

[0020] Optionally, the auxiliary extraction channel is a composite channel structure, which includes a first channel segment, a second channel segment, and a third channel segment connected in sequence. The channel cavity of the second channel segment is annular. The first channel segment is used to communicate between the second channel segment and the inner cavity of the cavity body. The number of the first channel segments is set to a plurality, and the plurality of the second channel segments are arranged in an equidistant ring along the wall of the cavity body. The third channel segment is used to communicate between the second channel segment and the auxiliary control valve. The number of the third channel segments is set to M, where M is a positive integer greater than or equal to 1. The first channel segment is connected to the inner ring wall of the annular structure, and the third channel segment is connected to the lower end face of the second channel segment.

[0021] Optionally, the extension line of the central axis of the exhaust port of the secondary exhaust channel is perpendicular to the axis of the wafer.

[0022] Optionally, the extension line of the central axis of the exhaust port of the secondary exhaust channel is inclined to the axial direction of the wafer and forms an angle, the angle being between 20° and 60°, and the exhaust port is inclined upward.

[0023] Optionally, the main control valve is a swing valve.

[0024] Optionally, the secondary control valve is a butterfly valve.

[0025] Optionally, the main extraction channel and the auxiliary extraction channel share a single vacuum pump.

[0026] Optionally, the main extraction channel and the auxiliary extraction channel are connected to different vacuum pumps.

[0027] To achieve the above objectives, the present invention also provides a plasma processing apparatus, including a process chamber with controllable gas flow field and a support stage for supporting wafers.

[0028] The beneficial effects of this invention are as follows:

[0029] This invention uses the auxiliary extraction channel and auxiliary control valve in coordination with the main extraction channel and main control valve to adjust the flow field distribution in the process cavity, guide and eliminate the gas concentration gradient and edge dead zone in the radial direction of the wafer, and achieve consistency between the side angle of the outer ring trench or hole of the wafer and the central and edge areas of the surface roughness. Attached Figure Description

[0030] Figure 1 This is a diagram showing the gas flow field distribution in the unadjusted state in this invention;

[0031] Figure 2 This is a diagram showing the adjusted gas flow field distribution in this invention;

[0032] Figure 3 For the present invention Figure 1 Mid-top sectional view of the structure;

[0033] Figure 4 This is a schematic diagram of the structure of the present invention forming at least two ring structures;

[0034] Figure 5 This is a schematic diagram of the L-shaped auxiliary air extraction channel structure in this invention;

[0035] Figure 6 This is a schematic diagram of the L-shaped auxiliary air extraction channel in this invention, which has several transverse sections.

[0036] Figure 7 This is a schematic diagram of the structure of the auxiliary air extraction channel as a composite channel in this invention;

[0037] Figure 8 This is a schematic diagram of the structure in which the air extraction port is tilted in this invention.

[0038] Explanation of reference numerals in the attached figures

[0039] 1. Cavity body; 2. Wafer; 3. Inlet channel; 4. Main exhaust channel; 5. Secondary exhaust channel; 51. Horizontal section; 52. Vertical section; 53. First channel section; 54. Second channel section; 55. Third channel section. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, but do not exclude other elements or objects.

[0041] Current ICP etching equipment generally adopts a "top center air intake + bottom center single air extraction" structure. This structure creates a vertically downward flow field during wafer processing. Because the air intake is located at the top center of the cavity, the process gas, under the combined influence of gravity and axial suction negative pressure, is directed vertically towards the wafer center along the shortest path, forming a high-speed central jet. Meanwhile, the edge regions, being far from the air intake and obstructed by the top jet, experience a sharp decrease in airflow velocity and slow renewal, leading to gas stagnation and being "preemptively" carried away by the central jet. This results in a high concentration at the center and a low concentration at the edge, creating a radial concentration gradient. Figure 1 As shown in the flow field, the process gas concentration is high in the central region of the wafer and low in the edge region, forming a significant radial concentration gradient and edge dead zone. This results in inconsistencies between the wafer center and edge in terms of etching depth, sidewall angle, and wafer surface roughness, leading to a decrease in yield. At the same time, traditional adjustment methods can only coarsely adjust the overall pressure through the bottom main exhaust channel 4 and the swing valve, and cannot finely control the local flow field.

[0042] To address the problems existing in the prior art, embodiments of the present invention provide a process cavity with controllable gas flow field. This process cavity with controllable gas flow field has several auxiliary extraction channels 5 arranged on the side wall of the cavity body 1. The auxiliary extraction channels 5 are arranged in a ring at equal intervals, specifically around the vertical center line of the cavity body 1. The advantage of this arrangement is that it can guide the convection of process gas in the radial direction of the wafer 2 by pressure. In this way, through the cooperation of the main extraction channel 4 and the main control valve (swing valve), the flow field of the process gas can be changed, and the gas concentration in the central and edge regions of the wafer 2 can be balanced, so that the gas concentration in the central and edge regions remains consistent.

[0043] Specifically, such as Figure 1 and Figure 2 As shown, the process cavity with controllable gas flow field includes a cavity body 1, which has a chamber for supporting the wafer 2. The cavity body 1 adopts a general cylindrical structure. In the etching process, the cavity body 1 is not only the physical boundary of the process gas, but also the core component that determines the uniformity of the gas flow field and the consistency of the etching results, and is used to support the wafer 2. In the prior art, the wafer 2 is placed horizontally inside the cavity body 1.

[0044] An air inlet channel 3 is provided at the top of the cavity body 1. The air inlet channel 3 communicates with the cavity and is used to introduce process gas into the cavity body 1. Preferably, the air inlet channel 3 is located at the middle of the top of the cavity body 1. The air inlet channel 3 can be a pipe, a through hole, or a spray head structure, but is not limited to pipes, through holes, or spray heads.

[0045] The bottom of the cavity body 1 is provided with a main air extraction channel 4, which communicates with the cavity. Figure 1 and Figure 2 As shown, the main evacuation channel 4 can be a through hole or a pipe, but is not limited to either; a through hole is preferred. The main evacuation channel 4 is connected to a main control valve (not shown). The combined function of the main evacuation channel 4 and the main control valve is to regulate and isolate the gas flow and pressure inside the cavity within the wafer 2 etching vacuum system. The main evacuation channel 4 is connected to an external vacuum pump, and the main control valve is located on the gas flow channel to adjust the opening of the main evacuation channel 4.

[0046] The main control valve can be a butterfly valve, but it is not limited to butterfly valves.

[0047] To reduce costs, the butterfly valve in this application adopts an existing structure. Specifically, the butterfly valve includes a disc-shaped valve disc (butterfly plate) fixed on the valve stem, and the valve body is a short cylindrical shape. The valve stem only needs to rotate 90° to make the butterfly plate parallel (fully open) or perpendicular (fully closed) to the main air extraction channel 4, and the flow rate can be linearly adjusted at any intermediate angle. The edge of the butterfly plate forms a surface seal with the elastic valve seat (rubber or PTFE), and the extended end of the valve stem is equipped with an anti-push-out structure. The two ends of the valve body can be connected by flanges, clamps, or butt welding. The overall height is small and the weight is light, making it suitable for large-diameter pipelines of DN50–DN2000. When fully open, the flow resistance is close to that of the pipeline itself, and when closed, zero leakage is achieved through the elastic deformation of the valve seat.

[0048] Furthermore, a butterfly valve is installed at the outlet of the main extraction channel 4. By changing the angle of its rotating disc, the extraction rate is continuously adjusted, thereby controlling the pressure level and flow field distribution of the process gas in the cavity to meet the stringent requirements for different vacuum levels (such as mTorr level) during the etching process. At the same time, during non-process stages or emergency shutdowns, the butterfly valve can be quickly closed to disconnect the cavity from the vacuum pump, preventing backflow of external gas or oil molecules, and protecting the cleanliness and vacuum integrity of the cavity.

[0049] During the process of regulating the gas flow field distribution in the process of butterfly valve, since the butterfly valve can only adjust the flow area of ​​the main extraction channel 4 as a whole and change the average pressure in the cavity body 1, it cannot change the axial flow field shape fixed by the top air intake and the bottom single extraction. No matter how the butterfly plate opening changes, it only makes the central jet and the edge dead zone expand or shrink at the same time, and cannot redistribute the gas in space. Therefore, the problem of concentration gradient and uneven etching in the radial direction of wafer 2 still exists.

[0050] Therefore, the present invention provides a secondary air extraction channel 5 on the side wall of the cavity body 1, and the secondary air extraction channel 5 communicates with the cavity, such as... Figure 1 and Figure 2 As shown, it is worth noting that, Figure 1 In the example, the auxiliary exhaust channel 5 is closed, and gas cannot be extracted from the cavity body 1 from here. Figure 2In the example, the auxiliary exhaust channel 5 is in the open state, and gas can be extracted from the cavity body 1 through this channel.

[0051] Furthermore, multiple auxiliary exhaust channels 5 are provided, and these channels 5 are distributed in a ring shape at equal intervals along the circumference of the cavity body 1 (around the vertical center line of the cavity body 1), such as... Figure 3 As shown, by working in conjunction with the main extraction channel 4 and the butterfly valve, a controllable radial flow field is superimposed on the axial extraction flow field to reconstruct the three-dimensional coupled flow field morphology, thereby spatially redistributing the process gas, eliminating the radial concentration gradient and edge dead zone of wafer 2, and achieving synchronous improvement of etching uniformity in the central and edge regions of the wafer.

[0052] Specifically, the secondary exhaust channel 5 is located on the side wall of the cavity body 1, and the exhaust port (unlabeled) of the secondary exhaust channel 5 is located axially between the upper surface of the wafer 2 and the top wall of the cavity body 1, such as... Figure 1 and Figure 2 As shown; in this example, the exhaust port is located between the upper surface of wafer 2 and the top wall of cavity body 1, which avoids the ion sheath layer protecting the uniformity of plasma and covers the boundary layer. It can immediately remove high-concentration gas and create a radial pressure difference, guiding the gas in the central region of wafer 2 to diffuse to the edge region. It works in conjunction with the main exhaust channel 4 to form a three-dimensional coupled flow field, thereby eliminating the radial concentration gradient and edge dead zone in real time.

[0053] The ion sheath refers to the positively charged region left by the absorption of electrons by the wafer surface when plasma comes into contact with the solid surface. This results in the formation of an "ion acceleration zone" with a strong electric field, which is only 1 to 3 mm thick, in front of the wafer surface. This ion acceleration zone determines the ion energy and incident angle. If it is disturbed, it will destroy the etching uniformity.

[0054] The boundary layer refers to the thin layer of low velocity and high gradient formed in the region near the surface of wafer 2 when gas flows through it due to viscosity. The gas concentration and velocity change drastically, and it is the key area for controlling the pumping effect and the redistribution of the gas flow field.

[0055] Furthermore, N auxiliary extraction channels 5 are provided, and these N auxiliary extraction channels 5 are arranged in an equidistant ring along the side wall of the cavity body 1 (around the vertical center line of the cavity body 1) to establish an extraction flow field of process gas in the radial direction of the wafer 2, such as... Figure 2As shown, in coordination with the main extraction channel 4 and the main control valve, the three-dimensional coupled flow field within the cavity body 1 is reconstructed. In this example, N auxiliary extraction channels 5 are arranged in an equidistant ring along the sidewall of the cavity body to construct a 360° annular extraction array in the radial direction of the wafer 2. Through the local extraction of each auxiliary extraction channel 5, in coordination with the main extraction channel 4, the traditional single-axial flow field can be reconstructed into a three-dimensional coupled flow field that diffuses from the central region of the wafer 2 to the edge region of the wafer 2 and then to the sidewall of the cavity body 1. The high-concentration process gas in the central jet is extracted in real time and replenished to the edge region of the wafer 2, thereby eliminating the radial concentration gradient and edge dead zone, and achieving uniform etching of the entire wafer.

[0056] It should be noted that in one example, the central jet is located in the central region of wafer 2, and is directly opposite the center of the central region.

[0057] In the existing ICP etching chamber with "top center air intake + bottom air extraction", the volume concentration of process gas (such as CF4 / O2) at the center jet (central region) is about 8 to 12%; the volume concentration in the edge region is reduced to 2 to 4% because it is far from the main air extraction channel 4 and is bypassed by the top center jet. Due to the difference in gas volume concentration, the etching rate difference between the central region and the edge region of wafer 2 is more than 10%.

[0058] The annular auxiliary extraction channel 5 introduced in this application controls the gas flow rate radially from the wafer. By constructing a three-dimensional coupled flow field, the gas volume concentration in the central region of wafer 2 is reduced from 8-12% to 5.5-6.5%, and the gas volume concentration in the edge region of wafer 2 is increased from 2-4% to 5.0-6.0%. This reduces the concentration difference between the central and edge regions from approximately 8% to less than or equal to ±1%, making the gas concentration in the central and edge regions more consistent and avoiding the problem of inconsistent etching rates between the central and edge regions of the wafer.

[0059] Furthermore, the number of the auxiliary air extraction channels 5 is set to a positive integer greater than or equal to 3. Specifically:

[0060] When the number of auxiliary exhaust channels 5 is even, for example, it can be 4, 6, 8, or 10, but it is not limited to 4, 6, 8, or 10. Other values ​​will not be elaborated here. Figure 3In this example, the number of secondary exhaust channels 5 is set to 6. The even number of secondary exhaust channels 5 in this example allows the exhaust ports of the secondary exhaust channels 5 to be arranged symmetrically in pairs along the circumference at 180°. This divides the secondary exhaust channels 5 into several pairs, and the exhaust ports of each pair of secondary exhaust channels 5 form mirror low-pressure sinks in the radial direction, thereby canceling out the circumferential pressure waves and effectively suppressing standing wave resonance modes. This enables balanced adjustment of the radial flow field or flow rate throughout the entire domain, while ensuring the symmetry and stability of the flow field within the 360° range, thus significantly improving the etching uniformity of the central and edge regions of wafer 2.

[0061] When the number of secondary extraction channels 5 is odd, for example, it can be 3, 5, 7, or 9, but it is not limited to 3, 5, 7, or 9. Other values ​​will not be elaborated here. In this example, the angular spacing of the extraction ports relative to the secondary extraction channels 5 is a non-integer 180°. This provides standing wave resonance conditions when circumferential symmetry is broken, which can completely suppress radial standing wave resonance and the concentration fluctuations it causes. At the same time, there is no symmetrical convergence in any direction of the odd-numbered array, which facilitates independent fine-tuning of the extraction flow rate of each extraction port to achieve asymmetric flow rate compensation. In addition, it can easily avoid obstacles such as valves or observation windows of the cavity body 1, further improving the radial etching uniformity and layout flexibility of the wafer 2.

[0062] However, in actual installation and layout, when the number of auxiliary extraction channels 5 is even, valve assemblies can be connected in parallel along the same path, resulting in fewer pipelines, faster commissioning, and lower costs. However, circumferential flow field fluctuations will occur due to standing wave resonance. When the number of auxiliary extraction channels 5 is odd, standing wave resonance can be suppressed, thereby suppressing circumferential flow field fluctuations, resulting in a more uniform flow field and more flexible control. However, valve assemblies and pipelines for each auxiliary extraction channel 5 need to be laid out individually, leading to higher costs and maintenance workload compared to the scheme with an even number of auxiliary extraction channels 5. Therefore, choosing an even number of auxiliary extraction channels 5 is suitable for batch production with moderate uniformity requirements, while choosing an odd number is suitable for precision etching processes requiring high adjustment accuracy and flexibility. Those skilled in the art can choose the specific type according to actual needs, which will not be elaborated here.

[0063] In one embodiment, the distance between the lower edge of the vent and the upper surface of the wafer 2 along the axial direction is between 5 mm and 40 mm. Figure 1 and Figure 2 As shown, a evacuation zone covering 5mm to 40mm is formed along the axial direction of the wafer. In this example, the axial distance between the lower edge of the evacuation port and the upper surface of wafer 2 is strictly limited to 5mm to 40mm to simultaneously meet the requirements of both plasma stability and gas dynamics. Specifically:

[0064] The distances described below are all along the wafer axis, and are all described with the top surface of wafer 2 as the zero point. Figure 1 and Figure 2 In the example, the axis of the wafer is the vertical direction.

[0065] In the 0-5mm region, which is the ion sheath layer (typically 1-3mm thick), the electric field can reach hundreds of volts per millisecond. Any gas extraction disturbance will change the ion bombardment energy and incident angle, leading to morphological changes or deterioration of wafer 2 during etching. In this application, the lower edge of the gas extraction port is set higher than the ion sheath layer. During the actual etching process, this effectively prevents disturbance to the gas in the ion sheath layer, avoiding impact on the ion bombardment energy and incident angle. It is worth noting that the height of the gas extraction port in this application does not cover the region between 3mm and 5mm. This is an intentional transition zone to keep the gas extraction area away from the ion sheath layer, preventing gas trajectory deviation and edge focusing effects from reaching the ion sheath layer and disrupting etching uniformity. If gas extraction were performed within this transition zone, it would simultaneously disturb the electric field and flow field, causing dual uncertainties.

[0066] In the 5 to 15 mm region, which is a gas boundary layer, the gas flow rate is the lowest and the gas concentration gradient is the largest in the central and edge regions. In this application, the extraction port is set in this region to directly extract the high-concentration gas in the central region and move it to the low-concentration edge region, so as to establish a controllable radial pressure difference and effectively balance the concentration gradient between the central and edge regions.

[0067] The lower edge height of the extraction port in this application is set within the range of 5mm to 40mm. This covers both the 5mm to 15mm gas boundary layer and the area above the gas boundary layer, i.e., the area between 15mm and 40mm. For example, the height of the extraction port can be 5mm, 8mm, 10mm, 15mm, 20mm, and 40mm, but it is not limited to the above heights, which will not be elaborated here. This can be combined with the 5mm to 15mm extraction process to further expand the radial compensation range without impacting the top wall of the cavity body 1, avoiding gas backflow upwards or from the edge region to the center region; at the same time, it avoids contact with the ion sheath layer; ensuring that the three-dimensional coupled flow field can both uniformly distribute the gas concentration on the wafer surface and not generate additional disturbances to the plasma, which has practical commercial application value.

[0068] Along the axial direction of the wafer, the exhaust port of the secondary exhaust channel 5 can be set to one, two, three or more layers. The change in the number of layers is essentially to superimpose multiple radial low-pressure sinks on top of the wafer 2. The low-pressure sink can be understood as, in the etching equipment, artificially creating a local low-pressure area in the cavity body 1, whose pressure is lower than the surrounding gas environment, thereby generating a suction effect on the surrounding gas, causing the gas to flow to that point and be extracted.

[0069] It is worth noting that the more layers of the extraction port, the finer the axial extraction gradient. This can be understood as follows: from top to bottom, the first layer extracts a portion of the gas from the central jet towards the edge region of the wafer; the second layer extracts another portion of the gas from the central jet towards the edge region of the wafer, and so on for subsequent layers. This can be figuratively described as "layered peak trimming." Through multi-layer extraction, the high-concentration gas, originally only present at the central jet, is progressively compensated and expanded radially, ultimately resulting in three-dimensional compensation across the entire process space. Experiments show that, from the absence of the secondary extraction channel 5, to the single-layer installation of the extraction port, and finally to two or more layers, the concentration difference between the central and edge regions of wafer 2 decreases from 8% to ±1% for a single layer, and then to ±0.5% for two, three, or more layers.

[0070] In actual processes, the number of air extraction ports in the auxiliary air extraction channel 5 varies, specifically:

[0071] In one example, such as Figure 1 and Figure 2 As shown, there are multiple auxiliary air extraction channels 5, and the air extraction ports of the multiple auxiliary air extraction channels 5 are arranged at the same height on the side wall of the cavity body 1 to form a single-layer annular structure. Specifically, the number of air extraction ports can be set to 3, 4, 5, 6, 7, 8, 9, 10 or more, preferably 8 or 9.

[0072] It is worth noting that the more exhaust ports there are, the denser the 360° discrete low-pressure manifold array can be formed along the circumference of the cavity body 1, thereby better regulating the gas flow field within the cavity body 1. However, it should also be understood that as the number increases, the cost of valve groups and pipelines also increases linearly. The specific selection can be adjusted by those skilled in the art according to the actual etching process precision requirements, which will not be elaborated here.

[0073] In another example, such as Figure 3 As shown, there are multiple auxiliary extraction channels 5, which are arranged at at least two different heights on the sidewall of the cavity body 1 to form at least two annular structures. Each annular structure includes at least multiple auxiliary extraction channels to form at least two radial extraction flow fields along the axial direction of the wafer, such as... Figure 4As shown, the advantage of at least two layers over a single layer is that the two annular vents at different heights form a discrete low-pressure sink array with an axial gradient distribution above wafer 2, which can "layer-by-layer peak shaving" of the gas concentration profile under a process pressure of 5 to 50 mTorr, further compressing the ±1% radial concentration difference that can only be achieved by a single layer to ±0.5%, while reducing the thickness of the edge retention layer from 8 mm to 10 mm to 3 mm to 4 mm, effectively eliminating micro-trench defects at the top of the double-layer trench.

[0074] In addition, the upper extraction port allows the high-concentration gas in the upper boundary layer to move rapidly from the high-concentration area in the central region to the low-concentration area at the edge. The lower extraction port, in addition to supplementing the outward-moving gas from the upper extraction port, also entrains by-products inside the groove, achieving three-dimensional compensation of "upper extraction and lower replenishment". However, at the same time, at least two extraction ports can independently adjust the flow rate, which increases the fault redundancy. The number of valve groups and pipelines is also doubled compared to a single layer, increasing the cost by about 60% to 80%. Therefore, when the number of layers is localized, it is necessary to weigh the process window and economics comprehensively, which will not be elaborated here.

[0075] The edge retention layer refers to the annular region formed between the outer edge of the wafer 2 and the wall of the cavity body 1 in the horizontal direction. Because this edge retention layer is far from the bottom main extraction channel 4 and is affected by the central jet's bypass, the gas flow rate is significantly reduced, resulting in a low-flow-rate, high-concentration boundary layer where reaction byproducts and polymers easily accumulate. This layer is typically between 5 mm and 10 mm thick. If it is not removed in time, it will lead to two problems: firstly, a persistently high concentration of process gas in the edge region, causing differences in etching rates; secondly, the formation of an "edge dead zone," causing micro-trenches at the top of high aspect ratio trenches. The extraction port configuration of the auxiliary extraction channel 5 in this application, with one or at least two layers, can specifically reduce the edge retention layer thickness from 8 to 10 mm to 3 mm to 4 mm, effectively eliminating micro-trenches at the top of the trenches. Simultaneously, it can prevent the deposition of byproducts or polymers in this area, avoiding particulate contamination or sidewall roughness.

[0076] In the layout of at least two layers of exhaust ports in the secondary exhaust channel 5, there are also the following different configurations, as detailed below:

[0077] The following example uses the secondary exhaust channel 5 with two exhaust ports.

[0078] In one specific embodiment, such as Figure 4As shown, the number of secondary exhaust channels contained in each layer of the annular structure is consistent, so as to form at least two identical radial exhaust air fields. In the exhaust ports of the two layers of secondary exhaust channels 5, the number of exhaust ports in each layer is set to a certain number, and the number of exhaust ports in the two layers is consistent. For example, it can be 3, 4, 5, 6, 7, 8, 9, 10 or more, preferably 8 or 9. That is, when the number of exhaust ports of the upper secondary exhaust channel 5 is 8 or 9, the number of exhaust ports of the lower secondary exhaust channel 5 is also 8 or 9.

[0079] In this embodiment, setting the number of extraction ports in both layers to be exactly the same is to form two completely mirrored radial low-pressure fields above wafer 2: the extraction intensity, circumferential phase, and circumferential density of the two layers are exactly the same. This avoids flow field distortion caused by axial misalignment and also avoids additional eddies or sudden changes in gas concentration caused by interlayer differences. This "double copy" structure keeps the axial and radial coupled flow fields highly symmetrical, and only requires one calibration to control both layers simultaneously. It is simple to debug and suitable for advanced node etching with extremely high uniformity requirements and narrow process windows. At the same time, it can ultimately control the radial concentration gradient difference of the entire wafer 2 within ±0.5%.

[0080] In one specific embodiment, the number of secondary extraction channels included in two adjacent annular structures increases layer by layer from top to bottom along the wafer axis to form two distinct radial extraction flow fields. In the extraction ports of the two layers of secondary extraction channels 5, the number of extraction ports in each layer is set to several, and the number of extraction ports in the two layers is inconsistent. For example, the number of extraction ports in the upper and lower layers can be 3, 4, 5, 6, 7, 8, 9, 10, or more; however, in actual layout, the number of extraction ports in the upper layer is 6, and the number of extraction ports in the lower layer is 9. The advantage of this arrangement is that the upper layer forms a stronger single-point suction with fewer but more widely spaced sinks, which can quickly reduce the high concentration in the center, while the lower layer forms a fine radial gradient with denser low-pressure sinks, further compensating for the gas-deficient areas at the edges. Two layers of low-pressure sinks with different densities are superimposed axially, which both suppresses the central jet and fully entrains the edge retention layer, so that the radial concentration gradient of the entire wafer 2 is ultimately controlled within ±0.5%.

[0081] Of course, in other specific embodiments, the venting ports can be set to 3 or more layers, and there are different configurations within the 3 layers. For example, in one example, the number of venting ports in each layer is the same, for example, all are set to 8 or 9. In another example, the number of venting ports along the wafer axis increases layer by layer from top to bottom, for example, the upper layer is set to 6, the middle layer is set to 8, and the lower layer is set to 9. In a third example, the number of venting ports in the upper and lower layers is the same, while the number of venting ports in the middle layer is different from that in the upper and lower layers, for example, the number of venting ports in the upper and lower layers is set to 6, and the number of venting ports in the middle layer is set to 8 or 9.

[0082] In one implementation, such as Figure 1 and Figure 2 As shown, the outlet of the auxiliary extraction channel 5 is connected to the auxiliary control valve (not shown). The auxiliary control valve is located outside the cavity body 1. The outlet and the extraction port are arranged opposite to each other. The auxiliary control valve extracts the process gas from the cavity body 1 through the auxiliary extraction channel.

[0083] In this example, the secondary extraction channel is opened on the side wall of the cavity and connected to an independent secondary control valve in order to create a finely adjustable radial low-pressure manifold around wafer 2. This layout upgrades the "whole cavity coarse adjustment" that could only be completed by the bottom main extraction to "zone fine adjustment". This avoids disturbance to the central plasma and can extract high-concentration gas in real time at the edge, thereby cooperating with the main extraction channel 4 to reconstruct the three-dimensional coupled flow field and eliminate the radial concentration gradient and edge dead zone.

[0084] During operation, after the secondary control valve opens, a local low pressure is formed on the outer side of the cavity wall in the secondary extraction channel. Under the radial pressure difference, the gas inside the cavity body 1 is continuously extracted from the extraction port of the secondary extraction channel, and the extraction flow rate is independently controlled by the opening degree of the secondary control valve. By synchronously adjusting the secondary control valves of N secondary extraction channels, the gas distribution in the central and edge regions of wafer 2 can be dynamically balanced within a 360° range, achieving closed-loop flow field management of "simultaneous extraction and replenishment".

[0085] It is worth noting that the secondary control valve can be a butterfly valve, but it is not limited to butterfly valves. The secondary evacuation channel is connected to an external vacuum pump, and the butterfly valve is located in the gas movement path to control the gas flow rate. N secondary evacuation channels can be connected to the same vacuum pump, and the main evacuation channel 4 can also be connected to the secondary evacuation channels on the same vacuum pump. Furthermore, the position settings of the swing valve, the main evacuation channel 4, and the vacuum pump are consistent with the position settings of the butterfly valve, the secondary evacuation channels, and the vacuum pump, which will not be elaborated here.

[0086] Furthermore, the combination of the butterfly valve, the auxiliary extraction channel, and the vacuum pump in this invention, as well as the coordinated combination of the swing valve, the main extraction channel 4, and the vacuum pump, can also be used to regulate the pressure inside the cavity body 1 and maintain a constant pressure inside the cavity body 1. Specifically, when the combination of the swing valve, the main extraction channel 4, and the vacuum pump remains unchanged, when the pressure inside the cavity body 1 increases, the opening of the auxiliary extraction channel is increased by adjusting the butterfly valve, thereby increasing the pumping volume at the auxiliary extraction channel and thus reducing the pressure inside the cavity body 1; when the pressure inside the cavity body 1 decreases, the opening of the auxiliary extraction channel is decreased by adjusting the butterfly valve, thereby reducing the pumping volume at the auxiliary extraction channel and thus increasing the pressure inside the cavity body 1. Conversely, when the combination of the butterfly valve, the auxiliary extraction channel, and the vacuum pump remains unchanged, the pressure inside the cavity body 1 can also be regulated by adjusting the swing valve, which will not be elaborated further here.

[0087] Preferably, the combination of butterfly valve, auxiliary air extraction channel and vacuum pump in this application, in coordination with the combination of swing valve, main air extraction channel 4 and vacuum pump, can be used for pressure regulation in cavity body 1 with inconsistent air intake, and can also be used for pressure regulation in cavity body 1 with consistent air intake, which will not be elaborated here.

[0088] The swing valve consists of a pendulum-shaped gate, valve seat, valve stem, and drive mechanism. The gate is an arc-shaped or fan-shaped metal plate, which opens and closes by the reciprocating swing of the valve stem (usually 60° to 90°). The valve seat is a replaceable hard alloy or weld overlay. After the gate swings to its final position, it makes line contact with the valve seat to form a hard metal seal. The valve body has a straight or inclined flow channel, short structural length, low opening and closing torque, and is erosion resistant. It is commonly used in applications containing particles or under high temperature and pressure. The diameter range is DN100–DN1200. It can be installed horizontally or vertically, and can be driven manually, pneumatically, or electrically.

[0089] In one embodiment, a control device is further included, which is communicatively connected to the main control valve and the auxiliary control valve, for controlling the main control valve and the auxiliary control valve to work together to adjust the flow field distribution within the process chamber.

[0090] The control device can be understood as the host computer.

[0091] In practical use, the auxiliary exhaust channel has different configurations, such as a rectangular or L-shaped through-hole with an independently set cross-sectional channel cavity; and a composite channel structure, specifically:

[0092] In the first example, such as Figure 1 and Figure 2As shown, the independently set cross-sectional channel cavity is a rectangular through hole, and the cavity of the through hole is set horizontally. In this configuration, the height (vertical direction) of the auxiliary air extraction channel cavity is between 1.5mm and 4mm, for example, it can be 1.5mm, 2mm, 2.5mm, 3.5mm, 4mm, but it is not limited to the above dimensions, which will not be elaborated here.

[0093] In this example, the secondary extraction channel is made into a horizontal rectangular slit with a height of 1.5 mm to 4 mm, which can instantly form a high-speed low-pressure pool within the boundary layer. This provides sufficient radial pressure difference while avoiding interference between low-pressure pools caused by excessive width, and at the same time prevents particle blockage, ensuring precise and controllable radial airflow.

[0094] It is worth noting that in the three-dimensional structure, the cavity of the through hole is cylindrical, but not limited to cylindrical.

[0095] In the second example, such as Figure 5 As shown, the independently configured cross-sectional channel cavity is an L-shaped through hole, comprising a transverse section 51 and a vertical section 52. The transverse section 51 connects the inner cavity of the cavity body 1 with the vertical section 52. The transverse section 51 is horizontally disposed on the wall of the cavity body 1, and the vertical section 52 is vertically disposed on the wall of the cavity body 1. In this configuration, the cavity height of the transverse section 51 is between 1.5mm and 4mm, for example, it can be 1.5mm, 2mm, 2.5mm, 3.5mm, or 4mm, but not limited to the above dimensions, which will not be elaborated here. The cavity height of the vertical section 52 is between 40mm and 80mm, for example, it can be 40mm, 50mm, 60mm, 70mm, or 80mm, but not limited to the above dimensions, which will not be elaborated here.

[0096] In this example, the height of the lateral segment 51 of the L-shaped via is set to 1.5 mm to 4 mm to form a slit throttling region, which can instantly establish a controllable radial pressure difference within the boundary layer above wafer 2; the height of the vertical segment 52, 40 mm to 80 mm, provides sufficient airflow buffer and isobaric space, making the flow velocity at the horizontal slit outlet uniform and the flow direction stable, and cooperating with the bottom main pump to reconstruct the three-dimensional coupled flow field, which improves the pumping efficiency and avoids disturbing the plasma sheath.

[0097] Furthermore, in one example, such as Figure 6 As shown, in the L-shaped through hole, there is one vertical segment 52 and several horizontal segments 51, such as two, three, or more. In this configuration, several horizontal segments 51 are arranged in the same vertical direction and are connected to the vertical segment 52 respectively, and the several horizontal segments 51 are not connected to each other.

[0098] In the third example, such as Figure 7As shown, the auxiliary exhaust channel is a composite channel structure, which includes a first channel segment 53, a second channel segment 54, and a third channel segment 55 connected in sequence. The channel cavity of the second channel segment 54 has a ring-shaped structure (in a three-dimensional structure). The first channel segment 53 is used to connect the second channel segment 54 with the inner cavity of the cavity body 1. The number of the first channel segments 53 is set to a plurality, for example, 3, 4, 5, 6, 7, 8, or 9. The plurality of second channel segments 54 are arranged in a ring at equal intervals along the wall of the cavity body 1, and there is no connection between two adjacent second channel segments 54. The third channel segment 55 is used to connect the second channel segment 54 with the auxiliary control valve. The number of the third channel segments 55 is set to M, where M is a positive integer greater than or equal to 1, for example, 1, 2, 3, or more, preferably 1.

[0099] The first channel segment 53 is connected to the inner ring wall of the annular structure, and the third channel segment 55 is connected to the lower end face of the second channel segment 54.

[0100] In this example, a composite channel structure of "first channel segment 53 + annular second channel segment 54 + third channel segment 55" is adopted. The original scattered independent air extraction ports are first merged into a circumferential annular cavity, and then connected to one or more main pipes. The annular second channel segment 54 forms a 360° uniform low-pressure ring in the wall of the cavity body 1 to ensure symmetrical circumferential air extraction intensity. The first channel segment 53 uses several micro-holes (or slits) to uniformly draw the gas above the wafer 2 into the annular cavity to avoid local over-extraction. The third channel segment 55 is connected to an external valve group with at least one outlet, which can reduce the number of valve groups from several to a minimum of one, significantly reducing external pipelines, valve bodies and sealing points. This reduces the risk of particulate contamination, simplifies debugging and maintenance, and retains the ability to finely adjust the radial flow field, realizing efficient three-dimensional coupled flow field reconstruction of "multi-point air extraction + single-ring convergence + centralized control".

[0101] Of course, in other examples, the secondary exhaust channel is not limited to a through hole, but can also be a tubular structure, with a through hole being preferred.

[0102] In one embodiment, the suction port of the secondary suction channel is horizontally positioned to generate horizontal suction, such as... Figure 1 and Figure 2 As shown. In this embodiment, the gas intake direction is parallel to wafer 2, which can form a symmetrical, low-disturbance radial gas extraction field in the circumferential direction, quickly remove the high-concentration gas at the edge without disturbing the ion sheath layer, and ensure the uniformity of plasma concentration in the central and edge regions of the wafer.

[0103] In one embodiment, the extension line of the central axis of the exhaust port of the secondary exhaust channel 5 is inclined to the axial direction of the wafer 2, forming an angle between 20° and 60°, and the exhaust port is inclined upwards. The exhaust port of the secondary exhaust channel 5 is inclined, as... Figure 8 As shown, the tilt angle is between 20° and 60°, for example, it can be 20°, 30°, 40°, 50° and 60°, but it is not limited to 20°, 30°, 40°, 50° and 60°, which will not be elaborated here.

[0104] In this embodiment, the upward tilt angle of the air extraction port from 20° to 60° generates a downward entrainment airflow during extraction. This not only avoids the sensitive area of ​​the ion sheath layer, but also uses the tilt momentum to directly guide the central jet to the edge, enhancing the three-dimensional coupled flow field of the central region, edge region and side of wafer 2. This results in a thinner edge retention layer and a smaller concentration gradient, thereby achieving higher radial uniformity and a deeper trench bottom cleaning effect at the same extraction speed.

[0105] Of course, in other embodiments, for example, in the multi-layer configuration of the auxiliary air extraction channel 5, the horizontal setting of the air extraction port and the inclined setting of the air extraction port can be set separately or in combination, which will not be elaborated here.

[0106] In one embodiment, the gas flow field controllable process cavity further includes:

[0107] A gas sensor (not shown) is located within the cavity body 1, preferably in the central and edge regions of the wafer. Multiple sensors are provided to monitor the gas concentration at different locations in real time. This gas sensor can be a hydrogen sensor or a carbon dioxide sensor, but is not limited to either.

[0108] A pressure sensor (not shown) is installed on or outside the cavity body 1 to monitor the air pressure of the cavity body 1 in real time.

[0109] The processor (not shown) is located on or outside the cavity body 1 and is electrically connected to the gas sensor, pressure sensor, butterfly valve and swing valve. It is used to receive the detection signal from the gas sensor and calculate the corresponding gas concentration according to the preset algorithm.

[0110] Specifically, the processor controls the operation of the swing valve or butterfly valve based on the gas concentration signal collected by the gas sensor. When the concentration in the central and edge areas is consistent, or the gas pressure inside cavity 1 is normal, the swing valve or butterfly valve will not be activated. When the concentration in the central and edge areas is inconsistent, or the gas pressure inside cavity 1 is abnormal (too high or too low), the swing valve or butterfly valve will be activated. It is worth noting that when several butterfly valves are activated, the opening degree of several auxiliary extraction channels can change uniformly or inconsistently. The specific opening degree can be adjusted in real time according to different gas concentrations, which will not be elaborated here.

[0111] To address the problems existing in the prior art, embodiments of the present invention also provide a plasma processing apparatus, including the aforementioned process chamber with controllable gas flow field, and a support stage for supporting the wafer 2.

[0112] Furthermore, the gas flow field controllable process cavity of this invention is not only applicable to the etching equipment included in plasma processing equipment, but can also be seamlessly extended to chemical vapor deposition (CVD), physical vapor deposition (PVD), and atomic layer deposition (ALD) equipment. Through the same radial and axial coupled flow field control, the deposition gas concentration is made uniform, ensuring film thickness consistency and step coverage. It is also applicable to photoresist stripping equipment for quickly and uniformly removing residual polymers or metal etching byproducts, avoiding edge residues and re-deposition defects.

[0113] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the present invention. Furthermore, the present invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A process cavity with controllable gas flow field, characterized in that, include: The cavity body has a chamber for holding the wafer; An air inlet channel is located at the top of the cavity body and communicates with the cavity, for introducing process gas into the cavity; The main extraction channel is located at the bottom of the cavity body and communicates with the cavity; the main extraction channel is connected to the main control valve and is used to establish an extraction flow field of process gas along the axial direction of the wafer. A secondary exhaust channel is located on the side wall of the cavity body and communicates with the cavity. The horizontal plane of the exhaust port of the secondary exhaust channel is located above the supported wafer. The secondary exhaust channel is connected to a corresponding secondary control valve to establish an exhaust gas flow field in the radial direction of the wafer. There are multiple secondary exhaust channels, and the exhaust ports of the multiple secondary exhaust channels are arranged in a ring structure on the side wall of the cavity body. The control device is communicatively connected to the main control valve and the auxiliary control valve, and is used to control the main control valve and the auxiliary control valve to work together to adjust the flow field distribution in the process cavity and guide the elimination of gas concentration gradient and edge dead zone in the radial direction of the wafer.

2. The process cavity with controllable gas flow field according to claim 1, characterized in that, The air inlets of the multiple auxiliary air extraction channels are arranged at the same height on the side wall of the cavity body to form a single-layer ring structure for establishing a single-layer radial air extraction field within the cavity body.

3. The process cavity with controllable gas flow field according to claim 1, characterized in that, Multiple auxiliary extraction channels are arranged at at least two different heights on the sidewall of the cavity body to form at least two annular structures; each annular structure includes at least multiple auxiliary extraction channels for forming at least two radial extraction flow fields in the axial direction of the wafer.

4. The process cavity with controllable gas flow field according to claim 3, characterized in that, The number of auxiliary air extraction channels contained in each layer of the annular structure is consistent, so as to form at least two identical radial air extraction fields.

5. The process cavity with controllable gas flow field according to claim 3, characterized in that, The number of the secondary extraction channels contained in two adjacent annular structures increases from top to bottom along the wafer axis to form two distinct radial extraction flow fields.

6. The process cavity with controllable gas flow field according to claim 1, characterized in that, The distance between the lower edge of the vent and the upper surface of the wafer along the wafer axis is between 5 mm and 40 mm.

7. The process cavity with controllable gas flow field according to claim 1, characterized in that, The auxiliary air extraction channel is an independent channel structure, and the height of the channel cavity of the channel structure is between 1.5mm and 4mm.

8. The process cavity with controllable gas flow field according to claim 1, characterized in that, The auxiliary air extraction channel is an independent channel structure and has an L-shaped structure. The auxiliary air extraction channel includes a horizontal section and a vertical section. The horizontal section is used to connect the inner cavity of the cavity body and the vertical section. The height of the transverse section's channel cavity is between 1.5mm and 4mm; the lower opening of the vertical section is located on the bottom wall of the cavity body and communicates with the secondary control valve, and the height of the vertical section's channel cavity is between 40mm and 80mm.

9. The process cavity with controllable gas flow field according to claim 1, characterized in that, The auxiliary exhaust channel is a composite channel structure, which includes a first channel segment, a second channel segment, and a third channel segment connected in sequence. The channel cavity of the second channel segment is annular. The first channel segment is used to communicate between the second channel segment and the inner cavity of the cavity body. The number of first channel segments is set to a certain number, and the number of second channel segments is arranged in an equidistant ring along the wall of the cavity body. The third channel segment is used to communicate between the second channel segment and the auxiliary control valve. The number of third channel segments is set to M, where M is a positive integer greater than or equal to 1. The first channel segment is connected to the inner ring wall of the annular structure, and the third channel segment is connected to the lower end face of the second channel segment.

10. The process cavity with controllable gas flow field according to claim 1, characterized in that, The extension line of the central axis of the exhaust port of the secondary exhaust channel is perpendicular to the axis of the wafer.

11. The process cavity with controllable gas flow field according to claim 1, characterized in that, The extension line of the central axis of the exhaust port of the secondary exhaust channel is inclined to the axial direction of the wafer and forms an angle between 20° and 60°, and the exhaust port is inclined upward.

12. The process cavity with controllable gas flow field according to claim 1, characterized in that, The main control valve is a swing valve.

13. The process cavity with controllable gas flow field according to claim 1, characterized in that, The secondary control valve is a butterfly valve.

14. The process cavity with controllable gas flow field according to claim 1, characterized in that, The main extraction channel and the auxiliary extraction channel share a single vacuum pump.

15. The process cavity with controllable gas flow field according to claim 1, characterized in that, The main extraction channel and the auxiliary extraction channel are respectively connected to different vacuum pumps.

16. A plasma processing device, characterized in that, It includes a process chamber with controllable gas flow field as described in any one of claims 1 to 15, and a support stage for supporting wafers.

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