A filter device for removing etching products in a wet etching solution and an etching solution circulation system

Abstract

The application provides a filter device for removing etching products in a wet etching solution, comprising a shell, a liquid inlet, a liquid outlet and a filter structure, wherein the liquid inlet and the liquid outlet are located on the shell, the filter structure is located inside the shell, the filter structure comprises a plurality of filter surface components provided with filter surfaces at a non-zero angle with the horizontal; the filter surface comprises a precipitator structure containing precipitators with a diameter of 0.1mm-3mm, when the etching solution to be filtered passes through the precipitator structure, the etching products are adsorbed or precipitated on the precipitators; the filter structure is configured to make the etching solution to be filtered pass through the filter surfaces in the same process, and the process includes time, distance, filtering effect and / or the structure of the filter surface, and has the beneficial technical effects that the new filter structure increases the precipitation contact process, the multi-process synchronous filtering is adopted to ensure that the etching solutions to be filtered maintain the same filtering process to the greatest extent, and the design difficulty of the etching solution recycling system is reduced.

Description

Technical Field

[0001] This invention relates to a filtration device and an etching solution circulation system for removing etching products from wet etching solutions, and more particularly to a filtration device and an etching solution circulation system for removing etching products and circulating and regenerating etching solutions on a production line to continuously perform etching operations. Background Technology

[0002] In the fields of integrated circuits, photovoltaic panels, and LCD panels, various wet etching solutions are frequently used to etch wafers, photovoltaic silicon-based panels, and glass substrates. These etching solutions are diverse, including phosphoric acid, hydrofluoric acid, and nitric acid. As etching progresses, the concentration of etching products in the etching solution gradually increases, leading to a decrease in etching rate and saturation precipitation of etching products, which affects the etching process. Generally, replacing the etching solution with a new one is necessary to perform the etching operation more efficiently.

[0003] In existing wet etching technologies, there are various systems for removing etched product precipitates and circulating the etching solution. These systems are mainly divided into two categories. The first category uses cooling and dilution of the etching solution to reduce the saturation of the etched products, thereby causing them to precipitate, and then physical filtration is performed. The second category involves adding chemical reagents to the etching solution to cause a chemical reaction that causes the etched products to precipitate, and then physical filtration is performed.

[0004] In integrated circuit manufacturing, silicon nitride is an important non-conductive dielectric material, often used as a sacrificial layer and barrier layer. Wet etching is commonly used to remove thin films such as silicon nitride from wafers. It typically uses a phosphoric acid-containing etching solution at 160–180 degrees Celsius to etch the wafer. The main chemical reaction equations involved are as follows:

[0005] 3Si3N4+4H3PO4+36H2O=4(NH4)3PO4+9Si(OH)4.

[0006] During etching operations, the concentration of silicon compounds, one of the etching products of silicon nitride in the phosphoric acid etching solution, gradually increases. When the concentration rises to a certain level, it can cause contamination of the substrate, thus requiring the replacement of the phosphoric acid etching solution to avoid the silicon oxide compounds affecting the wafer manufacturing yield.

[0007] Existing methods for removing silicon compounds include cooling, precipitation, and filtration. However, these methods can lead to changes in the temperature and concentration of components in the etching solution. Typically, the treated etching solution needs to be heated and re-etched to meet the etching process requirements after removal and recycling. How to efficiently remove silicon nitride etching products from phosphoric acid etching solutions, extend the service life of the etching solution, reduce costs, and improve production efficiency has always been a significant challenge for engineers. Currently, only patent reports exist on the removal of etching products from phosphoric acid etching solutions during the recycling process for silicon nitride. These methods mainly involve cooling and adjusting the moisture content to convert the etching products into solid particles for precipitation, followed by conventional physical filtration. This approach suffers from numerous problems, including complex removal processes, low efficiency, poor stability of removal results, and high energy consumption, making it unsuitable for practical production.

[0008] All of the above methods for removing precipitates use conventional physical precipitation, which can easily lead to the accumulation of precipitate particles on the filter surface, affecting the filtration effect of the subsequent etching solution. In addition, the filtration structure is simple, and over a long period of time, the concentration of effective components in the etching solutions that are filtered and regenerated successively varies greatly. Before the solution is recycled back into the etching chamber, real-time adjustments are required, such as adjusting the amount of new etching solution added, to ensure that the effective components reach the same qualified concentration, which increases the design difficulty of the circulation system. Summary of the Invention

[0009] To address the above problems, this invention provides a filtration device and an etching solution circulation system for removing etching products from wet etching solutions. It employs a chemical reaction method to cause the etching products to precipitate or adsorb onto the surface of solid materials. A novel filtration structure is adopted to increase the precipitation contact process, and multi-process synchronous filtration is used to ensure that the etching solutions to be filtered maintain the same filtration process to the greatest extent possible, thereby reducing the design difficulty of the etching solution recirculation system.

[0010] The present invention provides a filtration device for removing etching products from wet etching solution, comprising a housing, an inlet, an outlet, and a filtration structure, wherein the inlet and the outlet are located on the housing, and the filtration structure is located inside the housing;

[0011] The filter structure includes several filter surfaces arranged from top to bottom, each having a filter surface at a non-zero angle to the horizontal.

[0012] The filter surface includes a precipitant structure containing a precipitant with a diameter of 0.1 mm to 3 mm. When the etchant solution to be filtered passes through the precipitant structure, the etching product is adsorbed or precipitated on the precipitant.

[0013] The filtration structure is configured such that the etching solution to be filtered passes through the filter surface in the same manner, the manner including time, distance, filtration effect and / or the structure of the filter surface.

[0014] Preferably, the filtration structure is a primary filtration structure, a secondary filtration structure, or a multiple filtration structure, wherein the primary filtration structure, the secondary filtration structure, and the multiple filtration structure cause the etching solution to pass through the filter surface once, twice, or multiple times, and the multiple filtration structure causes the etching solution to pass through the filter surface less than 10 times.

[0015] Preferably, the filter surface component of the primary filtration structure further includes a filter inlet configured to allow the etching solution to be filtered to pass through the filter surface only once.

[0016] Preferably, the filter surface component of the secondary filtration structure and the multiple filtration structure further includes a filter inlet and a secondary filter channel configured to pass the etching solution to be filtered through the filter surface two or more times.

[0017] Preferably, the filter structure is a hollow integral component, comprising, from top to bottom, a first filter surface component, a second filter surface component, ..., an Nth filter surface component whose lower surface is the filter surface.

[0018] Preferably, the etching product forms a chemical adsorption with the precipitant; or, the etching product forms a precipitate with the precipitant and then precipitates on the precipitant.

[0019] Preferably, the filter surface is sheet-like, conical, funnel-shaped, or curved.

[0020] Preferably, the filter surface has a multi-layer structure, and the diameter of the precipitating agent in each layer increases sequentially from top to bottom.

[0021] Preferably, the wet etching solution is phosphoric acid, and the etching product is a substance produced by etching silicon nitride.

[0022] An etching solution circulation system for real-time removal of etching products from wet etching solution is also provided, comprising a wet etching chamber and a filtration device as described above, connected in sequence by pipes.

[0023] The present invention has the following advantages: it adopts a novel filtration structure to increase the precipitation contact process and adopts multi-process synchronous filtration to ensure that the etching solutions to be filtered in succession maintain the same filtration process to the greatest extent, thereby reducing the design difficulty of the etching solution recycling system. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the etching solution circulation system in a wet etching process according to the present invention;

[0025] Figure 2 yes Figure 1 Schematic diagram of the intermediate filter device 14;

[0026] Figure 3 yes Figure 2 A front view of the external structure of the intermediate filter 120;

[0027] Figure 4 yes Figure 2 A vertical sectional view of a filter 120;

[0028] Figures 5a-5b yes Figure 2 A vertical sectional view of another filter 120;

[0029] Figure 5c This is an enlarged schematic diagram of the filter element;

[0030] Figure 5d This is an enlarged schematic diagram of the filter surface;

[0031] Figures 5e to 5f yes Figures 5a-5b Top view of filter 120;

[0032] Figure 5g This is a vertical sectional view of a filter 120 including a secondary filtration structure;

[0033] Figure 5h This is a vertical sectional view of a filter 120 that includes a multi-stage filtration structure;

[0034] Figure 6a yes Figure 2 A vertical sectional view of another filter 120;

[0035] Figure 6b yes Figure 6a Top perspective view of the filter;

[0036] Figure 6c yes Figure 6a A vertical sectional view of a filter 120. Detailed Implementation

[0037] The following detailed description, in conjunction with the accompanying drawings, illustrates the specific implementation of the filter and etching solution circulation system for removing etching products from wet etching solutions according to the present invention.

[0038] In the accompanying drawings, for ease of description, the dimensions of layers and regions are not actual proportions. When a layer (or film) is referred to as being "on" another layer or substrate, it may be directly on the other layer or substrate, or there may be intermediate layers. Similarly, when a layer is referred to as being "below" another layer, it may be directly below, and one or more intermediate layers may be present. Additionally, when a layer is referred to as being "between" two layers, it may be the only layer between the two layers, or one or more intermediate layers may be present. The same reference numerals always denote the same elements. Furthermore, when the term "connection" is used between two components, it includes physical connections, which, unless expressly specified in the specification, include, but are not limited to, electrical connections, contact connections, and wireless signal connections.

[0039] like Figures 2-6c As shown, the present invention provides a filtration device 14 for removing etching products from wet etching solutions, including a filter 120. The filter 120 includes a housing (not shown), an inlet 101, an outlet 113, and a filter structure 241. The inlet 101 and the outlet 113 are located on the housing, and the filter structure 241 is located inside the housing. The filter structure 241 includes a plurality of filter surface components arranged from top to bottom, each having a filter surface at a non-zero angle to the horizontal. That is, the filter structure 241 includes filter surfaces at a non-zero angle to the horizontal (e.g., ...). Figure 4 Filter surfaces 2411 to 2415 in the middle, Figures 5b-5c The filter surface in the middle is 24112~241N2. Figure 6a The filter structure 241 is configured such that the filter surface (e.g., 2411-241N) passes through the etchant to be filtered, thereby increasing the precipitation contact process. Figure 4 Filter surfaces 2411 to 2415 in the middle, Figures 5b-5c The filter surface in the middle is 24112~241N2. Figure 6a The processes of the filter surfaces (2411-241N) are the same or similar to ensure that the etch solutions to be filtered in succession maintain the same degree of filtration as much as possible, reducing the design difficulty of the etch solution recirculation system. The process includes filtration time, filtration distance, filtration effect and / or the filter surface (e.g., Figure 4 Filter surfaces 2411 to 2415 in the middle, Figures 5b-5c The filter surface in the middle is 24112~241N2. Figure 6a The structure of the filter surface (2411-241N); the filter surface (such as...) Figure 4 Filter surfaces 2411 to 2415 in the middle, Figures 5b-5c The filter surface in the middle is 24112~241N2. Figure 6a The filter surfaces (2411-241N) are single-layer or multi-layer structures. Each filter surface includes a precipitant structure (not shown) containing a precipitant (not shown) with a diameter of 0.1 mm to 3 mm. When the etching solution to be filtered passes through the precipitant structure, the etching product adsorbs or precipitates onto the precipitant. The precipitant can be spherical or approximately spherical, and the diameter refers to its particle size range. To avoid insufficient filtration due to only one pass, any filter surface can adopt a multi-layer precipitant structure, such as... Figure 5dAs shown, the mesh size of the precipitant in each layer of the precipitant structure increases sequentially from top to bottom, achieving the technical effect of conventional physical filtration by first filtering larger precipitates and then filtering smaller precipitates. The diagram shows four layers of precipitant structure, with precipitant diameters of 3mm, 2mm, 1mm, and 0.1mm in each layer, meaning the filter surface includes a precipitant structure containing precipitants with diameters ranging from 0.1mm to 3mm. Of course, the number of layers is not always as shown. Figure 5d The four layers shown can be fewer or more than four. The diameter of the precipitant in the topmost precipitant structure is 3 mm, the diameter of the precipitant in the bottommost precipitant structure is 0.1 mm, and the diameter of the precipitant in the middle precipitant structures can be uniformly set. The applicant will not elaborate further here.

[0040] like Figure 3 As shown, to effectively remove soluble chemicals that are difficult to remove from chemicals, the present invention provides a filter 120, which includes a housing, a support 121, inlets 101 and 102, flow controllers 111 and 112, an outlet 113, and a valve 114. Figures 4-5d , Figure 6a All views are sectional views of the vertical plane where the geometric center of the main structure of filter 120 is located. The internal filtration structure 241 of filter 120 is described in detail below. The etching solution to be filtered enters the internal filtration structure 241 of the housing through the inlet 101 to physically filter the precipitates. Preferably, the filter surface can react with the remaining etch product dissolved in the etching solution to precipitate it on the precipitating agent. The structure of the filtration structure 241 allows soluble chemicals that are difficult to remove to fully contact and react with the chemicals set in the filtration structure to form easily separable precipitates or chemically adsorb onto the surface of the solid substance, i.e., the precipitating agent. The filtrate after filtration by the filtration structure 241 flows out from the bottom outlet 113. The precipitating agent here includes adsorbents, precipitants, etc. According to actual needs, the required substances that can react with the impurities in the sample to be treated are set on the filtration structure 241. Figure 3 The filter 120 shown is used to remove etching products from the etching solution after wet etching, which significantly reduces the processing time of silicon compounds, increases the precipitation contact process, reduces costs, and has a good removal effect.

[0041] like Figure 2 As shown, the filtration device 14 also includes a precipitant addition structure 140, which adds a precipitant to the etch solution to react with the remaining dissolved etching products and precipitate them, thereby effectively removing the etching products. The precipitated etch solution is then introduced into the filter 120 for filtration. It should be noted that since the etch solution has been treated by the sedimentation tank 13, the amount of precipitant added to the filtration device 14 is small and not enough to lower the temperature of the etch solution. Therefore, there is no need to heat the regenerated etch solution.

[0042] It should be noted that the remaining etching products refer to the etching products remaining in the etching solution to be filtered after physical precipitation or other steps before the filter 120. If there is no physical precipitation, sedimentation or adsorption before the filter 120, the remaining etching products refer to the original etching products in the etching solution to be filtered exported from the wet etching chamber. In this invention, the applicant will not elaborate further.

[0043] like Figures 4 to 6c As shown, the filter surface (e.g.) Figure 4 Filter surfaces 2411 to 2415 in the middle, Figures 5b-5c The filter surface in the middle is 24112~241N2. Figure 6a The filter surface (2411-241N) is funnel-shaped, sheet-shaped, conical, or curved, and forms a non-zero angle with the horizontal. This means the main body of the filter surface does not contain a flat surface, allowing the etchant to flow along the filter surface from the top edge to the bottom edge, increasing the filtration process and thus increasing the contact between the precipitate and the filter surface, resulting in better precipitate removal. It should be noted that "the main body of the filter surface does not contain a flat surface" means that the non-horizontal surface with filtration function is greater than 50% of the total area with filtration function. Surfaces without filtration function, i) those that only react with the remaining dissolved etching products to precipitate, or ii) non-permeable dense surfaces, whether horizontal or non-horizontal, are not considered part of the filter surface.

[0044] like Figure 4 As shown, filter surfaces 2411-2415 are funnel-shaped, and are the filter surface components mentioned above. The flow regulator 111 adjusts the flow of the precipitant from the inlet 101 along the guide channel 211. The flow regulator 112 adjusts the flow of the etching solution containing etching products from the inlet 102 into the guide channel 212. Under the regulation of the flow regulator, the precipitant and the etching solution flow out of the guide channels 211 and 212 respectively, come into contact with each other, react, and precipitate. Simultaneously, the precipitant falls onto the filter structure 241 and continues to react. The filter structure 241 is a multi-stage filtration structure, as shown... Figure 4The diagram shows five filter layers. After multiple adsorption and precipitation processes, the time, distance, and structure of the etchant passing through these filter layers are identical to those of the filter surfaces. Due to the funnel-shaped design, the bottom of the upper funnel becomes clogged. Therefore, the filter structure 241 can be configured to include more than five filter layers, such as ten layers to ensure complete adsorption and precipitation of the etching products in the etchant, thus achieving consistent filtration efficiency. The centerlines of the guide channels 211 and 212 intersect at an angle θ1 greater than 0° and less than or equal to 180°. The bottom of the funnel forms an angle θ2 greater than 0°, preferably greater than 90°. This means that when the funnel filter surfaces 2411-2415 are vertically symmetrically arranged, the funnel walls are gentler and longer, resulting in a longer precipitation reaction time and a longer filtration distance, thus increasing the precipitation contact process. However, when both θ1 and θ2 are equal to 180°, this filtration structure can be understood as existing conventional physical filtration technology, which cannot provide the remaining etching products with the necessary time for precipitation and is prone to clogging. Preferably, θ1 < θ2, and neither is equal to 180°. A filter inlet 251 is also provided to guide the filtered etching solution to be collected along the pipe 223 to the bottom of the housing. To avoid insufficient filtration due to only one filtration, such as... Figure 4 Any of the funnel-shaped filter surfaces 2411 to 2415 shown can adopt a multi-layered precipitant structure, such as... Figure 5d As shown, the mesh size of the precipitant in each layer of the precipitant structure increases sequentially from top to bottom, achieving the technical effect of conventional physical filtration by first filtering larger precipitates and then filtering smaller precipitates. The diagram shows four layers of precipitant structure, with precipitant diameters of 3mm, 2mm, 1mm, and 0.1mm in each layer, meaning the filter surface includes a precipitant structure containing precipitants with diameters ranging from 0.1mm to 3mm. Of course, the number of layers is not always as shown. Figure 5d The four layers shown can be fewer or more than four. The diameter of the precipitant in the topmost precipitant structure is 3 mm, the diameter of the precipitant in the bottommost precipitant structure is 0.1 mm, and the diameter of the precipitant in the middle precipitant structures can be uniformly set. The applicant will not elaborate further here.

[0045] The applicant discovered Figure 4 The filtration device with funnel-shaped filter surface can only carry out a single filtration process, that is, the etching solution to be filtered is filtered from filter surface 2411 to filter surface 2415, which is the entire funnel-shaped filter surface. After a certain time, the upper funnel-shaped filter surface will be blocked by sediment, resulting in inconsistent filtration process outside the specific time interval. Of course, through actual monitoring, the length of the specific time can be known, and then a new funnel-shaped filter surface can be replaced in time within this specific time. However, due to the funnel-shaped design, the specific time is relatively short, and the operation is frequent.

[0046] Therefore, the applicant proposes an alternative design with the exact same filtration process, wherein the filtration structure is a single-pass filtration structure in which the etching solution to be filtered passes through the filter surface only once, and the filter surface component of the single-pass filtration structure further includes a filter inlet configured to allow the etching solution to be filtered to pass through the filter surface only once. For example... Figures 5a to 5f As shown, the filter 120 includes a filter structure, which is a hollow, integral structure. From top to bottom, it includes a first filter surface component 2411a, a second filter surface component 2412a, a third filter surface component 2413a, a fourth filter surface component 2414a, a fifth filter surface component 2415a, a sixth filter surface component 2416a, a seventh filter surface component 2417a, an eighth filter surface component 2418a… and an Nth filter surface component 241Na, each including an upper surface 24111, 24121, 24131, 24141, 2415a, etc. 1, 24161, 24171, 24181…241N1, and the lower surfaces opposite to each upper surface, namely filter surfaces 24112, 24122, 24132, 24142, 24152, 24162, 24172, 24182…241N2, and vertical cavities connecting adjacent filter surface components, such as vertical cavity 24110 connecting the first filter surface component 2411a and the second filter surface component 2412a, and vertical cavity 24120 connecting the second filter surface component 2412a and the third filter surface component 2413a. The etching solution to be filtered enters the hollow integral structure through the inlet 101, and is filtered sequentially through filter surfaces 24112, 24122, 24132, 24142, 24152, 24162, 24172, 24182…241N2 before falling onto the first filter channel 2511, the second filter channel 2512, the third filter channel 2513, the fourth filter channel 2514, the fifth filter channel 2515, the sixth filter channel 2516, the seventh filter channel 2517…the Nth filter channel 251N, as shown below. Figure 5a As shown, the upper edge of each filter tank is fixed to the bottom edge of the corresponding filter surface component, and the bottom edge extends outside the filter structure, allowing the etching solution filtered only once to fall to the bottom of the housing. Therefore, the regenerated etching solution falling to the bottom of the housing is filtered only once, resulting in good uniformity. With this design, the etching solution undergoes the same process through the filter surface; that is, the time, distance, filtration effect, and structure of the filter surface are the same. It should be noted that, to avoid insufficient filtration due to only one pass, any of the filter surfaces 24112, 24122, 24132, 24142, 24152, 24162, 24172, 24182…241N2 can adopt a multi-layered precipitant structure, such as… Figure 5dAs shown, the mesh size of the precipitant in each layer of the precipitant structure increases sequentially from top to bottom, achieving the technical effect of conventional physical filtration by first filtering larger precipitates and then filtering smaller precipitates. The diagram shows four layers of precipitant structure, with precipitant diameters of 3mm, 2mm, 1mm, and 0.1mm in each layer, meaning the filter surface includes a precipitant structure containing precipitants with diameters ranging from 0.1mm to 3mm. Of course, the number of layers is not always as shown. Figure 5d The four layers shown can be fewer or more than four. The diameter of the precipitant in the topmost precipitant structure is 3 mm, the diameter of the precipitant in the bottommost precipitant structure is 0.1 mm, and the diameter of the precipitant in the middle precipitant structures can be uniformly set. The applicant will not elaborate further here.

[0047] like Figure 5b As shown, when the upper surfaces 24121, 24131, 24141, 24151, 24161, 24171, 24181…241N1 are all dense, non-permeable structures, the upper edges of the first filter channel 2511, the second filter channel 2512, the third filter channel 2513, the fourth filter channel 2514, the fifth filter channel 2515, the sixth filter channel 2516, the seventh filter channel 2517…the Nth filter channel 251N can be fixed to the upper surface of the next filter element. The lower and bottom edges of the upper surfaces 24121, 24131, 24141, 24151, 24161, 24171, 24181...241N1 extend beyond the filter structure, allowing the etching solution that is filtered only once to fall into the bottom of the housing. Therefore, the regenerated etching solution that falls into the bottom of the housing is filtered only once, resulting in good uniformity. With this design, the etching solution to be filtered passes through the filter surface in the same way, that is, the time, distance, filtration effect and structure of the etching solution to be filtered through the filter surface are the same.

[0048] It should be noted that, for Figures 5a-5b In the filter structure shown, where the upper surfaces 24121, 24131, 24141, 24151, 24161, 24171, 24181...241N1 of each filter element are dense, non-permeable structures, the first filter inlet 2511, the second filter inlet 2512, the third filter inlet 2513, the fourth filter inlet 2514, the fifth filter inlet 2515, the sixth filter inlet 2516, the seventh filter inlet 2517...the Nth filter inlet 251N can be omitted to further simplify the filter design. The impact of omitting the filter inlets on the filtration effect in practical applications is almost negligible.

[0049] Based on the identical filtration process with more filtration cycles, the applicant proposed another design with the same filtration process. This filtration structure is a secondary filtration structure, where the etching solution to be filtered passes through the filter surface twice. The filter surface component of the secondary filtration structure further includes a filter inlet and a secondary filter channel configured to allow the etching solution to be filtered to pass through the filter surface only twice. For example... Figure 5g As shown, in the second filter element 2412a and the third filter element (not shown, e.g.) Figure 5b Secondary filter channels 2611 and 2612, connecting to the next filter surface component, are respectively provided outside the vertical cavity at the lower edge of 2413a). The first filter inlet 2511 and the second filter inlet 2512 are removed. The secondary filter channels 2611 and 2612 respectively guide the filter surface (such as the filter surface of the first filter surface component 2411a and the second filter surface component 2412a) to filter the filter surface (such as the filter surface of the first filter surface component 2411a and the second filter surface component 2412a). Figure 5b The 24112 and 24122) primary filtration etching solutions are reintroduced into the hollow integrated structure and respectively to the third filter surface component (not shown, e.g., 24112 and 24122). Figure 5b 2413a), the fourth filter element (not shown, e.g.) Figure 5b The filter surface of 2414a in the middle (e.g.) Figure 5b The etching solution is filtered through filters 24132 and 24142, respectively, to obtain secondary filtered etching solutions. These solutions are then guided to the bottom of the housing via the third filter tank 2513 and the fourth filter tank 2514. This ensures that the etching solution, having only been filtered twice, falls to the bottom of the housing, resulting in good uniformity as the regenerated etching solution at the bottom is filtered twice. It should be noted that this design must ensure uniform injection of the etching solution, meaning that the continuous etching solution should fall entirely onto the filter surface of the second filter component 2412a above its lower edge. This prevents some of the etching solution from falling into the third filter tank 2513 after only one filtration and being collected at the bottom of the housing. This ensures that the etching solution passes through the filter surface at the same rate, meaning the time, distance, filtration effect, and structure of the filter surface are identical. It should also be noted that to avoid insufficient filtration due to only one filtration, any filter surface can employ a multi-layered precipitant structure, such as... Figure 5d As shown, the mesh size of the precipitant in each layer of the precipitant structure increases sequentially from top to bottom, achieving the technical effect of conventional physical filtration by first filtering larger precipitates and then filtering smaller precipitates. The diagram shows four layers of precipitant structure, with precipitant diameters of 3mm, 2mm, 1mm, and 0.1mm in each layer, meaning the filter surface includes a precipitant structure containing precipitants with diameters ranging from 0.1mm to 3mm. Of course, the number of layers is not always as shown. Figure 5dThe four layers shown can be fewer or more than four. The diameter of the precipitant in the topmost precipitant structure is 3 mm, the diameter of the precipitant in the bottommost precipitant structure is 0.1 mm, and the diameter of the precipitant in the middle precipitant structures can be uniformly set. The applicant will not elaborate further here.

[0050] Similarly, based on obtaining the same filtration process through multiple cycles of filtration, the filtration structure is a multi-stage filtration structure. This multi-stage filtration structure causes the etching solution to pass through the filter surface multiple times, ensuring that the number of times the etching solution passes through the filter surface is less than 10. The filter surface components of the multi-stage filtration structure also include a filter inlet and a secondary filter channel configured to allow the etching solution to pass through the filter surface only multiple times. (Reference) Figure 5h A filtration device design with unlimited filtration times and identical or similar filtration processes can be obtained. Secondary filter channels 2611, 2612, 2613, 2614, 2615, 2416, 2417… and the Nth filter channel 241Na are respectively provided outside the vertical cavity at the lower edge of the second filter surface component 2412a, the third filter surface component 2413a, the fourth filter surface component 2414a, the fifth filter surface component 2415a, the sixth filter surface component 2416a, the seventh filter surface component 2417a… and a secondary filter channel (not shown) connecting to the next filter surface component, thereby achieving a design that filters the same number of times. This design, by controlling the flow rate and speed of the etchant to be filtered as described in the secondary filtration structure, ensures that the etchant passes through the filter surface in the same manner, i.e., the time, distance, and structure of the etchant passing through the filter surface are the same. Preferably, the filtration is performed no more than 10 times, meaning the filtration structure allows the etching solution to pass through the filter surface no more than 10 times, as described above in a single-pass filtration structure. Figure 5a , Figure 5b and Figure 6a The filter structure shown), secondary filter structure ( Figure 5g The filter structure shown) and the multiple filter structure ( Figure 5h The specific technical solution will not be elaborated further here. It should be noted that both the inlet filter tank and the secondary filter channel include a surrounding structure (not shown) or are enclosed by a housing to ensure that the filtrate is guided from the upper edge of the inlet filter tank to the outside of the filter structure, rather than overflowing horizontally to the upper surface of the next filter element (such as...). Figure 5b Beyond the design of the filter surface itself, this ensures that the filtrate is guided by the secondary filtration channel to the next filter surface component. It should be noted that, to avoid insufficient filtration due to only one pass, any component of the filter surface can adopt a multi-layered sedimentation agent structure, such as... Figure 5dAs shown, the mesh size of the precipitant in each layer of the precipitant structure increases sequentially from top to bottom, achieving the technical effect of conventional physical filtration by first filtering larger precipitates and then filtering smaller precipitates. The diagram shows four layers of precipitant structure, with precipitant diameters of 3mm, 2mm, 1mm, and 0.1mm in each layer, meaning the filter surface includes a precipitant structure containing precipitants with diameters ranging from 0.1mm to 3mm. Of course, the number of layers is not always as shown. Figure 5d The four layers shown can be fewer or more than four. The diameter of the precipitant in the topmost precipitant structure is 3 mm, the diameter of the precipitant in the bottommost precipitant structure is 0.1 mm, and the diameter of the precipitant in the middle precipitant structures can be uniformly set. The applicant will not elaborate further here.

[0051] Better, such as Figures 5a-5d The filter 120 housing is as follows Figure 5e The horizontal cross-section shown is a uniform cylindrical structure with a circular shape, or, as... Figure 5f The horizontal cross-section shown is a uniform tetrahedral prism structure, and the internal filter components can be designed to adapt to the shape.

[0052] Therefore, the applicant also proposed another conical filter surface design with the exact same filtration process. This filtration structure is a single-pass filtration structure, where the etching solution to be filtered passes through the filter surface only once. The filter surface component of this single-pass filtration structure also includes a filter inlet configured to allow the etching solution to pass through the filter surface only once. For example... Figures 6a-6cAs shown, the etching solution to be filtered enters the first vertical inlet channel 27110 from the inlet 101, then enters the first horizontal circulation channel 2711, and then enters the first vertical outlet channel 27111. The etching solution to be filtered is sequentially introduced downwards into the Nth vertical inlet channel, the Nth horizontal circulation channel, the conical filter surface, and the Nth vertical outlet channel. The outer wall of the first vertical outlet channel 27111 is fixedly connected to and passes through the filter surface 2411 and the first filter guide groove 2511 below. That is, the outer wall of the Nth vertical outlet channel is fixedly connected to and passes through the filter surface and the corresponding Nth filter guide groove below to sequentially transport the etching solution to be filtered to each layer of conical filter surface below. The Nth vertical inlet channel, the Nth horizontal circulation channel, and the Nth vertical outlet channel constitute the Nth ring-guided channel (as shown in the figure). A vertical liquid inlet channel 27110, a first horizontal circulation channel 2711, and a first vertical liquid outlet channel 27111 constitute a first ring-shaped liquid guiding channel. The Nth horizontal circulation channel is configured to uniformly contact the conical filter surface, i.e., the first horizontal circulation channel 2711, the second horizontal circulation channel 2712, the third horizontal circulation channel 2713, the fourth horizontal circulation channel 2714, the fifth horizontal circulation channel 2715, the sixth horizontal circulation channel 2716, the seventh horizontal circulation channel 2717…the Nth horizontal circulation channel 271N is configured to uniformly contact the conical filter surfaces 2411, 2412, 2413, 2414, 2415, 2416, 2417…241N, which will not be elaborated further here. The lower part of the first horizontal circulation channel 27111 and the other horizontal circulation channels (i.e.…) Figure 6c (The dark part shown) releases the etchant to be filtered onto the conical filter surface 2411. Similarly, the etchant to be filtered passes from top to bottom through the conical filter surfaces 2411, 2412, 2413, 2414, 2415, 2416, 2417...241N and the corresponding identical conical filter channels below them: the first filter channel 2511, the second filter channel 2512, the third filter channel 2513, the fourth filter channel 2514, the fifth filter channel 2515, the sixth filter channel 2516, the seventh filter channel 2517...the Nth filter channel 251N. The filtrate that has only been filtered once is guided to the bottom of the housing. The bottom edge of each filter channel extends out of the corresponding conical filter surface above, so that the etchant that has only been filtered once falls into the bottom of the housing. Therefore, the regenerated etchant that falls into the bottom of the housing is filtered once, resulting in good uniformity. It should be noted that, to avoid insufficient filtration due to only one filtration, any of the filter surfaces 2411, 2412, 2413, 2414, 2415, 2416, 2417…241N can adopt a multi-layered precipitant structure, such as… Figure 5dAs shown, the mesh size of the precipitant in each layer of the precipitant structure increases sequentially from top to bottom, achieving the technical effect of conventional physical filtration by first filtering larger precipitates and then filtering smaller precipitates. The diagram shows four layers of precipitant structure, with precipitant diameters of 3mm, 2mm, 1mm, and 0.1mm in each layer, meaning the filter surface includes a precipitant structure containing precipitants with diameters ranging from 0.1mm to 3mm. Of course, the number of layers is not always as shown. Figure 5d The four layers shown can be fewer or more than four. The diameter of the precipitant in the topmost precipitant structure is 3 mm, the diameter of the precipitant in the bottommost precipitant structure is 0.1 mm, and the diameter of the precipitant in the middle precipitant structures can be uniformly set. The applicant will not elaborate further here.

[0053] in addition Figure 6a The filter 120 shown also includes a fixing structure (not shown) that is disposed through each conical filter surface and the corresponding filter inlet trough to fix each conical filter surface and the corresponding filter inlet trough.

[0054] It should be noted that, as Figure 5d The filter surfaces 24112 and 24122 shown (e.g.) Figure 4 Filter surfaces 2411 to 2415 in the middle, Figures 5b-5c The filter surface in the middle is 24112~241N2. Figure 6a The filter surface (2411-241N) has a multi-layer structure, each layer including a precipitant structure. The diameter of the precipitant in each layer increases sequentially from top to bottom, meaning the mesh size of the precipitant structure increases sequentially from top to bottom. For example... Figure 5g The illustrated two-filter structure consists of filter surface components 2411a and 2412a, each comprising only one layer of precipitant structure. However, the mesh size of the precipitant in the precipitant structure of filter surface component 2411a is greater than that of the precipitant in the precipitant structure of filter surface component 2412a. That is, in all two-filtration processes, each filter surface component includes a single layer of precipitant with an increasing mesh size. Figure 5h The multi-filter structure shown can similarly adopt a tiered set of precipitant structures, which the applicant will not elaborate on here. It should be noted that all precipitants in the above-described precipitant structures have the same or similar diameters, that is, the size of the precipitants in the same precipitant structure remains basically consistent.

[0055] Preferably, the above Figures 5a to 5h , Figure 6a In a corresponding embodiment, the filter surface further includes a particle blocking structure (not shown) located at the lower edge of the filter surface.

[0056] The present invention has the following advantages: it adopts a novel filtration structure to increase the precipitation contact process and adopts multi-process synchronous filtration to ensure that the etching solutions to be filtered in succession maintain the same filtration process to the greatest extent, thereby reducing the design difficulty of the etching solution recycling system.

[0057] like Figures 4 to 6c In each filter 120, a precipitant can be added simultaneously at the inlet 101 to react with the etching products, such as dissolved silicon compounds, in the etching solution to be filtered, and to precipitate them. Furthermore, each filter surface 241 (e.g.) Figure 4 Filter surfaces 2411 to 2415 in the middle, Figures 5b-5c The filter surface in the middle is 24112~241N2. Figure 6a The filter surfaces 2411 to 241N include structural portions made using effective chemical components of a precipitation promoter to further precipitate and remove residual etching products by filtration; each filter surface 241 (e.g. Figure 4 Filter surfaces 2411 to 2415 in the middle, Figures 5b-5c The filter surface in the middle is 24112~241N2. Figure 6a The filter surfaces 2411 to 241N have a permeable layer (not shown) with selective permeability, which is configured to have a desired pore size for the permeation of certain specific substances.

[0058] The permeation layer (not shown) and filter surface (as described above) involved in the various filtration devices mentioned above Figure 4 Filter surfaces 2411 to 2415 in the middle, Figures 5b-5c The filter surface in the middle is 24112~241N2. Figure 6a The filter surface (2411-241N) has an average pore size of less than 0.22 micrometers. The precipitating agent involved is selected from any one or more of molecular sieves, ion exchange resins, alumina, zirconium oxide, titanium oxide, silicon oxide, and organosilicon compounds, or substances modified with surface groups of any one or more of the above precipitating agents. The surface group modification refers to modification using one or more of the surface groups of fluorine, sulfonic acid, carboxyl, cyclohexyl, trimethylaminopropyl, propylbenzenesulfonate, ethylenediamine-N-propyl, and the above precipitating agents. The precipitating agent also includes silicon, silica polymers, silicon carbide, polymers containing hydroxyl groups, polymers containing carboxyl groups, and any one or more of the above precipitating agents with fluorine-based modification materials. The precipitating agent includes one or a combination of water, hydrofluoric acid, ammonium fluoride, and ammonium bifluoride. When the etching solution to be filtered passes through the precipitating agent structure, the etching product forms a chemical adsorption or physical adsorption with the precipitating agent, or the etching product forms a precipitate with the precipitating agent and then precipitates on the precipitating agent.

[0059] Preferably, the present invention is applied to silicon nitride etching using phosphoric acid as the wet etching solution, wherein the etching product is a substance generated during the etching of silicon nitride.

[0060] like Figure 1 As shown, an etching solution circulation system for real-time removal of etching products from wet etching solution is also provided, including a wet etching chamber 10, a sedimentation tank 13, and various filtration devices 14 connected in sequence by pipes 15. For example, a phosphoric acid-containing etching solution is used to wet etch the silicon nitride portion of the wafer in the etching chamber 10, resulting in silicon compounds as etching products in the etch solution after etching. The etch solution containing silicon compounds flows into the sedimentation tank 13 of the filtration chamber through pipes 15 for sufficient sedimentation. The sedimentation tank 13 includes the process of adding a precipitation promoter to react with the precipitation promoter before the etching products become saturated, thereby precipitating and forming the etch solution to be filtered. The etch solution to be filtered enters the various filtration devices 14 mentioned above to remove precipitates, particles, and other solid impurities. It then flows directly back to the wet etching chamber 10 through the circulation pipe or flows back to the wet etching chamber 10 after adding replenishing new etch solution. In the process of using the above-mentioned processing system, no additional heating or cooling operations are required, significantly shortening the processing time of the etch solution after etching. The number and location of pumps 11 and valves 12 are set according to actual needs. For example, in the filter device connected to the wet etching chamber, the power unit (such as pumps) and flow control device (such as valves) of the wet etching chamber provide liquid flow power and control the liquid flow rate to the filter device. Since the filter surface has adopted a sedimentation-promoting agent structure, the etching solution circulation system provided by the present invention can eliminate the need for filtration or sedimentation before the filter device to remove etching products using a sedimentation tank 13. That is, the present invention may exclude the sedimentation tank 13 and the removal process in which the sedimentation tank 13 participates, which will not be elaborated here.

[0061] Preferably, it also includes a new etching solution replenishment system (not shown), wherein the new etching solution replenishment system is located after the filter device 14.

[0062] This invention provides a filtration device and an etching solution circulation system for removing etching products from wet etching solutions. It adopts a novel filtration structure to increase the precipitation contact process, and uses multi-process synchronous filtration to ensure that the etching solutions to be filtered in successive processes maintain the same filtration process to the greatest extent, thereby reducing the design difficulty of the etching solution recirculation system. Furthermore, it adds a precipitant component to the filtration structure to further remove residual dissolved silicon compounds. It has the beneficial effects of effectively extending the service life of the etching solution, reducing the amount and frequency of etching solution replacement, reducing costs, and improving the efficiency of etching operations on the production line.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A filter device for removing etching products in a wet etching solution, comprising a housing, an inlet and an outlet on the housing, and a filter structure inside the housing, wherein the filter structure comprises a plurality of filter surface components configured with filter surfaces at a non-zero angle with the horizontal; the filter surface comprises a precipitant structure comprising precipitants with diameters of 0.1mm-3mm, and when the etching solution to be filtered passes through the precipitant structure, the etching products and the precipitants form adsorption or precipitation on the precipitants; the filter structure is configured to make the etching solution to be filtered pass through the filter surfaces in the same way, including time, distance, filtering effect and / or the structure of the filter surfaces; the filter surface comprises a plurality of layers of precipitant structures, and the precipitants in each layer increase in mesh from top to bottom; the filter structure is a primary filter structure, a secondary filter structure or a multiple filter structure, the primary filter structure, the secondary filter structure and the multiple filter structure make the etching solution to be filtered pass through the filter surfaces once, twice or multiple times, and the multiple filter structure makes the etching solution to be filtered pass through the filter surfaces less than 10 times; the filter surface component of the primary filter structure further comprises a guide channel configured to make the etching solution to be filtered pass through the filter surfaces only once; the filter surface components of the secondary filter structure and the multiple filter structure further comprise a guide channel and a secondary guide channel configured to make the etching solution to be filtered pass through the filter surfaces twice or multiple times; the filter structure is hollow and integral, and comprises the filter surface components with their lower surfaces being the filter surfaces from top to bottom; the etching products and the precipitants form chemical adsorption, or the etching products and the precipitants form precipitation on the precipitants; the filter surface is sheet-shaped, conical, funnel-shaped or curved; the wet etching solution is phosphoric acid, and the etching products are substances produced by etching silicon nitride; and a wet etching solution circulation system for removing etching products in a wet etching solution, comprising a wet etching chamber and a filter device for removing etching products in a wet etching solution according to any one of claims 1-8 connected in sequence by pipes.

9. A wet etching solution circulation system for removing etching products in a wet etching solution, comprising a wet etching chamber and a filter device for removing etching products in a wet etching solution according to any one of claims 1-8 connected in sequence by pipes. ​ ​ ​ 2. The filter device for removing etching products in a wet etching liquid according to claim 1, wherein ​ 3. The filter device for removing etching products in a wet etching liquid according to claim 2, wherein ​ 4. The filter device for removing etching products in a wet etching liquid according to claim 2, wherein ​ 5. The filter device for removing etching products in a wet etching liquid according to claim 1, wherein ​ 6. The filter device for removing etching products in a wet etching liquid according to claim 1, wherein ​ 7. The filter device for removing etching products in a wet etching liquid according to claim 1, wherein ​ 8. The filter device for removing etching products in a wet etching liquid according to claim 1, wherein ​ ​

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