Preparation method of semiconductor device and semiconductor device

Abstract

The invention discloses a preparation method of a semiconductor device and the semiconductor device, and the method comprises the steps: a wafer is provided, an aluminum-containing metal layer and a passivation layer are formed on the wafer, the passivation layer is of a multi-layer structure stacked on the metal layer in sequence, and the passivation layer comprises an oxide dielectric layer; etching the passivation layer by adopting multiple groups of etching gases corresponding to the multi-layer structure to form an opening region exposing part of the metal layer; executing a cleaning process to at least clean byproducts in the opening area; wherein the plurality of groups of etching gases comprise a first etching gas used for etching the oxide dielectric layer, and the first etching gas comprises a first fluorine-containing gas with a low carbon-fluorine ratio and a first auxiliary gas used for removing a carbon-containing polymer generated in the etching process. According to the invention, the defect of a polymer formed in the etching process of the passivation layer is overcome, and the yield of semiconductor device products is improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a method for preparing a semiconductor device and a semiconductor device. Background Art

[0002] In the semiconductor manufacturing process, a pad needs to be formed to prepare for the subsequent packaging process. In the related art, the cover layer on the metal layer (such as aluminum) is usually dry-etched and cleaned to form the pad. However, in the subsequent defect detection process, there are still densely distributed polymer defects in the open area of ​​the pad on the wafer. These polymers have a relatively high adhesion to the pad area and are difficult to remove through traditional cleaning processes, which reduces the performance and reliability of the pad, and further affects the yield of semiconductor device products. Summary of the invention

[0003] In view of at least one technical problem in the related art, the purpose of the present application is to provide a method for preparing a semiconductor device.

[0004] In order to solve the above technical problems, on the one hand, the present application provides a method for preparing a semiconductor device, comprising:

[0005] Providing a wafer, on which a metal layer containing aluminum and a passivation layer are formed, the passivation layer is a multi-layer structure sequentially stacked on the metal layer, and the passivation layer includes an oxide dielectric layer;

[0006] Using multiple sets of etching gases corresponding to the multi-layer structure, etching the passivation layer to form an opening area exposing a portion of the metal layer;

[0007] performing a cleaning process to at least clean the byproducts in the opening area;

[0008] The plurality of etching gas groups include a first etching gas for etching the oxide dielectric layer, the first etching gas includes a first fluorine-containing gas with a low carbon-fluorine ratio and a first auxiliary gas, and the first auxiliary gas is used to remove carbon-containing polymers generated during the etching process.

[0009] In some embodiments, the first fluorine-containing gas includes trifluoromethane and carbon tetrafluoride; in the first etching gas, the gas flow ratio of trifluoromethane to carbon tetrafluoride is 5:(24-26);

[0010] And / or, a gas flow rate ratio of the first fluorine-containing gas to the first auxiliary gas is less than 4.

[0011] In some embodiments, the first auxiliary gas includes oxygen;

[0012] In the first etching gas, the gas flow ratio of trifluoromethane to oxygen is 10:(19-21).

[0013] In some embodiments, the gas flow rate of carbon tetrafluoride contained in the first fluorine-containing gas is in the range of 480 sccm to 520 sccm, and the gas flow rate of the first auxiliary gas is in the range of 190 sccm to 210 sccm.

[0014] In some embodiments, a photoresist layer is formed on the passivation layer, and the first etching gas further includes a second auxiliary gas for hardening the photoresist layer; and etching the passivation layer using multiple groups of etching gases corresponding to the multi-layer structure includes:

[0015] The photoresist layer is used as a mask and the plurality of etching gases are used to etch the corresponding layer structures in the passivation layer in stages; after etching the passivation layer, the remaining thickness of the photoresist layer is greater than a preset thickness value.

[0016] In some embodiments, the second auxiliary gas includes hydrogen, and a gas flow ratio of the second auxiliary gas to the first auxiliary gas is (1-2):(19-21).

[0017] In some embodiments, the preset thickness value is greater than or equal to 1000 angstroms.

[0018] In some embodiments, the passivation layer further includes an etch stop layer, and the etch stop layer is located between the metal layer and the oxide dielectric layer; the method further includes:

[0019] After etching the passivation layer to the etch stop layer, a second etching gas is used to etch the opening area to remove byproducts generated during the etching process.

[0020] In some embodiments, the second etching gas includes a second fluorine-containing gas with a low carbon-fluorine ratio and a third auxiliary gas, and a gas flow ratio of the second fluorine-containing gas to the third auxiliary gas is 1:(18-20).

[0021] In some embodiments, the second etching gas satisfies at least one of the following:

[0022] The second fluorine-containing gas includes carbon tetrafluoride;

[0023] The third auxiliary gas includes oxygen;

[0024] The gas flow rate of the third auxiliary gas is in the range of 1800 sccm to 2000 sccm.

[0025] On the other hand, the present application also provides a semiconductor device, which is manufactured using any of the above-mentioned methods for manufacturing a semiconductor device.

[0026] On the other hand, the present application also provides a chip, comprising any of the semiconductor devices described above.

[0027] On the other hand, the present application also provides an electronic device, comprising any of the semiconductor devices described above.

[0028] The semiconductor device manufacturing method and the semiconductor device of the present application have at least the following beneficial effects:

[0029] By using multiple sets of etching gases to etch the multilayer structure in the passivation layer on the wafer, an opening area of ​​the metal layer containing aluminum is formed and cleaned. The multiple sets of etching gases include a first etching gas for etching the oxide dielectric layer in the passivation layer, and the first etching gas includes a first fluorine-containing gas with a low carbon-fluorine ratio and a first auxiliary gas. By adjusting the etching gas to the first fluorine-containing gas with a low carbon-fluorine ratio and removing the fluorine-containing gas with a high carbon-fluorine ratio, the aluminum-containing polymer defects formed during the etching process of the passivation layer can be fundamentally reduced. In addition, by adding the first auxiliary gas to the first etching gas to remove the carbon-containing polymer generated during the etching process, and etching in combination with the first fluorine-containing gas with a low carbon-fluorine ratio, the polymer defects formed during the etching process of the passivation layer are fundamentally solved, which not only reduces the subsequent cleaning burden, but also improves the performance and reliability of the formed pad without increasing the process cost, thereby helping to improve the yield of semiconductor device products. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 It is a schematic diagram of defect detection results of a wafer corresponding to a pad formed by an etching gas used in a related technology.

[0032] Figure 2 is a flow chart of a method for preparing a semiconductor device according to some embodiments.

[0033] Figure 3 is a schematic diagram of the structure of a passivation layer before and after etching according to some embodiments;

[0034] Figure 4is a schematic diagram of a process of changing etching process parameters according to some embodiments;

[0035] Figure 5 It is a schematic diagram of defect detection results of a wafer corresponding to the pad formed in Example 1 of the present application.

[0036] Figure 6 It is a schematic diagram of defect detection results of the wafer corresponding to the pad formed in Control Example 1.

[0037] Figure 7 It is a schematic diagram of defect detection results of the wafer corresponding to the pad formed in Control Example 2.

[0038] Among them, the reference numerals in the figure are: 301, photoresist layer, 302, nitride dielectric layer, 303, silicon-rich oxide layer, 304, silicon oxide layer, 305, oxynitride dielectric layer, 306, etch stop layer, 307, metal layer, 301', etched photoresist layer, 320, opening area. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0040] The "one embodiment" or "embodiment" referred to below refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. In the description of the present invention, unless otherwise clearly specified and limited, the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "top", "bottom", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0041] When a numerical range is disclosed in this application, the above range is deemed to be continuous and includes the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all sub-ranges included therein. Exemplary, for example, a specified range of "1 to 10" or "1-10" should be deemed to include any and all sub-ranges between the minimum value 1 and the maximum value 10. Specifically exemplary, exemplary sub-ranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0042] It should be understood that when describing the structure of a component, when a layer or a region is referred to as being located "on" or "above" another layer or another region, it may mean that it is directly located on the other layer or another region, or that other layers or regions are included between it and the other layer or another region. Moreover, if the component is turned over, the layer or a region will be located "below" or "beneath" another layer or another region.

[0043] In the related art, the cover layer on the metal layer (such as aluminum) is usually dry-etched and cleaned to form a pad. However, in the subsequent defect detection process, the wafer still has densely distributed polymer defects in the open area of ​​the pad. These polymers have a relatively high adhesion to the pad area and are difficult to remove through traditional cleaning processes, which reduces the performance and reliability of the pad, and further affects the yield of semiconductor device products.

[0044] Specifically, in the related art, for example, the coating on the aluminum-copper alloy is dry-etched, and the etching gas used in the original old process is C 4 F 8 (octafluorocyclobutane), CHF 3 (Trifluoromethane), CF 4 (carbon tetrafluoride), O 2 (oxygen) four gases, exemplarily, in the stage of etching the oxide layer in the capping layer, C 4 F 8 , CHF 3 CF 4 and O 2 The gas flow rates can be 28sccm, 100sccm, 420sccm and 120sccm respectively. After that, the bonding pad is formed by stripping and cleaning. Finally, the wafer corresponding to the formed bonding pad is inspected for defects. The wafer inspection results are as follows: Figure 1 shown. Figure 1Schematic diagram of defect detection results of a wafer corresponding to a pad formed by an etching gas used in the related art, wherein Figure 1 The middle left picture is a schematic diagram of the electronic scanning of the wafer. Figure 1 The middle right picture is an optical micrograph of a chip unit in the wafer on the left. Figure 1 It can be seen that there are densely distributed polymer defects in the open area of ​​the pad of the wafer (such as the circled part in the right figure). The inventors found that these polymers are formed by the fluorine in the etching gas and the aluminum in the etching area, and these aluminum-containing polymers have a relatively high adhesion with the aluminum in the pad area, resulting in the subsequent cleaning ability of the traditional cleaning process being insufficient to remove these polymer areas, affecting the yield of semiconductor device products.

[0045] In order to solve the above-mentioned polymer defect problem, the related art mainly considers increasing the polymer removal ability. For example, by adding gas to remove the polymer in the degumming stage, the polymer removal ability in the degumming stage is increased, but the added gas is easy to corrode the electrostatic chuck (ESC), greatly shortening the service life of the ESC and increasing production costs. In addition, since the polymer removal ability is jointly determined by the degumming stage and the cleaning stage, the fluctuation of any machine parameter will affect the final removal effect of the polymer, resulting in low product stability.

[0046] In view of this, the present application provides a method for preparing a semiconductor device and a semiconductor device to solve the technical problems caused by polymer defects generated during dry etching in the related art.

[0047] Figure 2 is a flow chart of a method for manufacturing a semiconductor device according to some embodiments. It should be understood that the order of some of the following operations can be interchanged. Figure 2 As shown, the method for preparing a semiconductor device comprises the following steps:

[0048] In operation 202 , a wafer is provided. A metal layer containing aluminum and a passivation layer are formed on the wafer. The passivation layer is a multi-layer structure sequentially stacked on the metal layer. The passivation layer includes an oxide dielectric layer.

[0049] In this embodiment, the wafer may be a single-layer structure or a multi-layer structure. The material of the wafer includes one or a combination of semiconductor material, insulating material, and conductor material. The structure and / or material of the wafer is not specifically limited here.

[0050] A metal layer containing aluminum and a passivation layer can be sequentially formed on the wafer by a deposition process. Specifically, the metal layer can be located on the surface of the wafer to achieve metal interconnection between chips by forming pads. The passivation layer is wrapped on the metal layer away from the surface of the wafer to play an isolation role. The passivation layer here is a multi-layer structure stacked in sequence.

[0051] In this embodiment, the passivation layer at least includes an oxide dielectric layer. As an example only, the material of the oxide dielectric layer may include but is not limited to one or more of silicon oxide, silicon-rich oxide (SRO), etc. Figure 3 As shown, the oxide dielectric layer includes a silicon-rich oxide layer 303 and a silicon oxide layer 304 .

[0052] Optionally, the passivation layer further includes at least one or more of a nitride dielectric layer, an oxynitride dielectric layer, etc. Exemplarily, continue as Figure 3 As shown, the nitride dielectric layer 302 may be located on the surface of the oxide dielectric layer away from the metal layer 307, and the oxynitride dielectric layer 305 may be located on the surface of the oxide dielectric layer close to the metal layer 307. As an example only, the material of the nitride dielectric layer may include but is not limited to silicon nitride, and the material of the oxynitride dielectric layer may include but is not limited to silicon oxynitride, etc.

[0053] In operation 204, multiple sets of etching gases corresponding to the multi-layer structure are used to etch the passivation layer to form an opening area exposing a portion of the metal layer.

[0054] The plurality of etching gas groups include a first etching gas for etching the oxide dielectric layer, the first etching gas includes a first fluorine-containing gas with a low carbon-fluorine ratio and a first auxiliary gas, and the first auxiliary gas is used to remove carbon-containing polymers generated during the etching process.

[0055] In the embodiment, during the dry etching of the passivation layer, multiple groups of etching gases are used to perform etching respectively to etch a portion of the passivation layer material and a portion of the metal layer on the metal layer to form a Figure 3 The opening area 320 of the exposed metal layer 307 is formed in the chip. The opening area is used as the opening of the pad to realize the metal interconnection between the chips. Optionally, the multiple groups of etching gases refer to etching gases including multiple different gas compositions and / or different gas flow rates. Different groups of etching gases can be used to etch different layers of the multi-layer structure. For example, for Figure 3 In the passivation layer structure shown in , different groups of etching gases can be used to etch the nitride dielectric layer, the oxide dielectric layer and the oxynitride dielectric layer. Each group of etching gases includes at least a main etching gas, which refers to a suitable gas that can react with the materials of different layers to be etched in the passivation layer and generate volatile gas products, such as a fluorine-containing etching gas.

[0056] In an embodiment, the plurality of etching gases include a first etching gas for etching the oxide dielectric layer, wherein the first etching gas includes a first fluorine-containing gas with a low carbon-fluorine ratio and a first auxiliary gas. The low carbon-fluorine ratio refers to a low carbon and fluorine content. Specifically, the fluorine-containing etching gas generally includes CF 4 , CHF 3、 CH 2 F 2 , CH 3 F and other gases with low carbon-fluorine ratios, as well as C 4 F 8 , C 4 F 6 , C 5 F 8 Optionally, the first fluorine-containing gas in the first etching gas is selected from CF 4 , CHF 3 At least one gas with a low carbon-fluorine ratio, rather than C 4 F 8 Gases with high carbon-fluorine ratios.

[0057] In an embodiment, the first auxiliary gas is used to remove carbon-containing polymers generated during the etching process. Exemplarily, the first auxiliary gas is a gas capable of reducing the generation of carbon-containing polymers, such as oxygen.

[0058] In operation 206 , a cleaning process is performed to clean at least the byproducts in the opening region.

[0059] In an embodiment, after the etching process is performed, a cleaning process such as a wet process may be performed to clean the formed opening area and the wafer to clean the surface of the opening area and the byproducts on the wafer, such as residual reactants, etc. Exemplarily, the cleaning agent used in the wet process may include but is not limited to hydrofluoric acid, sulfuric acid, etc.

[0060] The inventors conducted elemental analysis on the polymer defects in the related art and determined that the polymer was aluminum trifluoride (AlF 3 ). In order to reduce the polymer defects, the inventors first considered reducing the proportion of fluorine in the etching gas from the source of reducing the polymer generation. 4 F 8 , CHF 3 CF 4 and O 2 Take the etching of four gases as an example. Among the etching gases used in the original process, C 4 F 8Contains the most F atoms, so by removing the gas C with a high carbon-fluorine ratio 4 F 8 , and the first fluorine-containing gas with a low carbon-to-fluorine ratio is used to solve the problem of polymer defects.

[0061] In the above embodiment, by adjusting the etching gas to a first fluorine-containing gas with a low carbon-fluorine ratio and removing the fluorine-containing gas with a high carbon-fluorine ratio, the aluminum-containing polymer defects formed during the etching process of the passivation layer can be fundamentally reduced. In addition, by adding a first auxiliary gas to the first etching gas to remove the carbon-containing polymer generated during the etching process, and etching in combination with the first fluorine-containing gas with a low carbon-fluorine ratio, the polymer defects formed during the etching process of the passivation layer are fundamentally solved, which not only reduces the subsequent cleaning burden, but also improves the performance and reliability of the formed pad without increasing the process cost, thereby helping to improve the yield of semiconductor device products.

[0062] In some embodiments, the gas flow ratio of the first fluorine-containing gas to the first auxiliary gas is less than 4. Optionally, the gas flow ratio of the first fluorine-containing gas to the first auxiliary gas is in the range of 2 to 4. Further optionally, the gas flow ratio of the first fluorine-containing gas to the first auxiliary gas is in the range of 2.5 to 3.5.

[0063] In the original old process, the fluorine-containing gas in the etching gas includes C 4 F 8 This high carbon-fluorine ratio gas and CHF 3 and CF 4 , oxygen as auxiliary gas, the fluorine-containing gas (i.e. C 4 F 8 , CHF 3 and CF 4 ) to the gas flow rate of the auxiliary gas (i.e., oxygen) is usually greater than 4. In this embodiment, in addition to not using a high carbon-fluorine ratio gas in the first etching gas used to etch the oxide dielectric layer, and completely using a low carbon-fluorine ratio gas as the first fluorine-containing gas, the flow ratio between the first fluorine-containing gas and the first auxiliary gas is reduced to a value less than 4, that is, the proportion of the first auxiliary gas in the first etching gas is increased to reduce the residual carbon-containing polymer after etching. According to the defect detection results of the wafer, this embodiment can solve the problem of polymer defects in the related art by adjusting the gas process parameters of the etching gas as a whole. In this way, the subsequent cleaning burden is further reduced, which is conducive to improving the yield of semiconductor device products.

[0064] In some embodiments, the first fluorine-containing gas includes trifluoromethane and carbon tetrafluoride. In the first etching gas, the gas flow ratio of trifluoromethane to carbon tetrafluoride is 5:(24-26). Exemplarily, the gas flow ratio can be a boundary value in 5:(24-26) or any integer or decimal value in the range. Further preferably, in the first etching gas, the gas flow ratio of trifluoromethane to carbon tetrafluoride is 5:25.

[0065] Continue to use C in the original process mentioned above 4 F 8 , CHF 3 CF 4 and O 2 Take the etching with four etching gases as an example, the CHF in the corresponding etching stage 3 With CF 4 The gas flow rates are 100 sccm and 420 sccm respectively, and the gas flow ratio of the two is 5:21. In the present embodiment, the gas flow ratio of trifluoromethane to carbon tetrafluoride is 5:(24-26). By comparison, it can be seen that the present embodiment increases the gas flow rate of carbon tetrafluoride in the first etching gas. The wafer test results show that by increasing the gas flow rate of carbon tetrafluoride in the first etching gas on the basis of removing the fluorine-containing gas with a high carbon-fluorine ratio, not only the aluminum fluoride polymer defects can be improved, but also the etching rate can be increased to meet the etching rate requirements during the etching process.

[0066] In some embodiments, the gas flow rate of carbon tetrafluoride contained in the first fluorine-containing gas ranges from 480 sccm to 520 sccm. As an example only, the gas flow rate of carbon tetrafluoride can be 480 sccm, 490 sccm, 495 sccm, 500 sccm, 506 sccm, 513 sccm, 518 sccm, 520 sccm. Further preferably, the gas flow rate of carbon tetrafluoride can be 500 sccm. Correspondingly, the gas flow rate of trifluoromethane contained in the first fluorine-containing gas ranges from 100 sccm.

[0067] In some embodiments, the first auxiliary gas includes oxygen. In the first etching gas, the gas flow ratio of trifluoromethane to oxygen is 10:(19-21). The gas flow ratio can be a boundary value in 10:(19-21) or any integer or decimal value in the range. Further preferably, in the first etching gas, the gas flow ratio of trifluoromethane to oxygen is 10:20.

[0068] Continue to use C in the original process mentioned above 4 F 8 , CHF 3 CF 4 and O 2Take the etching with four etching gases as an example, the CHF in the corresponding etching stage 3 With O 2 The gas flow rates of 50 sccm and 50 sccm respectively, then the gas flow rate ratio of the two is 1:1. The gas flow rate ratio of trifluoromethane to oxygen in this embodiment is 10:(19-21). By comparison, it can be seen that this embodiment increases the gas flow rate of oxygen in the first etching gas. In this way, by increasing the flow rate of oxygen in the first etching gas, the new carbon-containing polymer generated by the introduction of too much carbon tetrafluoride can be solved, fundamentally reducing the polymer defect problem in the etching process.

[0069] In some embodiments, the gas flow rate of the first auxiliary gas ranges from 190 sccm to 210 sccm. As an example only, the gas flow rate of the first auxiliary gas may be 190 sccm, 192 sccm, 195 sccm, 200 sccm, 204 sccm, 208 sccm, 210 sccm, etc. Further preferably, the gas flow rate of the first auxiliary gas may be 200 sccm.

[0070] In some embodiments, a photoresist layer is formed on the passivation layer, and the first etching gas further includes a second auxiliary gas for hardening the photoresist layer; and etching the passivation layer using multiple groups of etching gases corresponding to the multi-layer structure includes:

[0071] The photoresist layer is used as a mask and the plurality of etching gases are used to etch the corresponding layer structures in the passivation layer in stages; after etching the passivation layer, the remaining thickness of the photoresist layer is greater than a preset thickness value.

[0072] In an embodiment, continue as Figure 3 As shown, the photoresist layer 301 covers the passivation layer. Before etching the passivation layer, the photoresist layer can be etched to form an etching pattern, and then the etched photoresist layer is used as a mask. Multiple groups of etching gases are used to etch the corresponding layer structures in the passivation layer in stages, and a group of etching gases is used to etch the corresponding layer structures in the passivation layer at different stages. In the process of etching the passivation layer, each group of etching gases will also etch the remaining non-opening area portion of the photoresist layer, resulting in a missing thickness of the photoresist layer. A second auxiliary gas for hardening the photoresist layer is added to the first etching gas. In the process of etching the passivation layer, the second auxiliary gas can harden the photoresist layer, reduce the etching amount of the first etching gas on the photoresist layer, so that the remaining thickness of the etched photoresist layer 301' is greater than the preset thickness value. In this way, by adding the second auxiliary gas to the first etching gas, the photoresist layer is hardened in advance, the remaining thickness of the photoresist layer is guaranteed, and the passivation layer in the non-opening area portion can be better protected.

[0073] In the case where a photoresist layer is formed on the passivation layer, after etching the passivation layer, de-germing can be first performed using, for example, an oxygen-containing plasma to remove the remaining photoresist layer on the unetched passivation layer, and then the above-mentioned cleaning process is performed to clean the by-products of the wafer and the opening area.

[0074] In some embodiments, the second auxiliary gas includes hydrogen, and the gas flow ratio of the second auxiliary gas to the first auxiliary gas is (1-2): (19-21). Taking the first auxiliary gas as oxygen and the second auxiliary gas as hydrogen as an example, the gas flow ratio of hydrogen to oxygen in the first etching gas is (1-2): any integer or decimal value in the boundary value or ratio range in (1-2): (19-21). Taking the gas flow range of the first auxiliary gas as 190sccm-210sccm as an example, based on this ratio range, it can be determined that the gas flow range of the second auxiliary gas is 10sccm-20sccm. Exemplarily, the gas flow of the second auxiliary gas can be 10sccm, 12sccm, 14sccm, 15sccm, 18sccm, 20sccm, etc. Further preferably, the gas flow of the second auxiliary gas can be 18sccm. In this way, by setting the second auxiliary gas to include hydrogen, while ensuring the hardening of the photoresist layer, it can be ensured that the adjusted gas composition meets the performance requirements for the opening morphology after etching.

[0075] In some embodiments, the preset thickness value is greater than or equal to 1000 angstroms. In this embodiment, the preset thickness value is 1000 angstroms, that is, after etching the passivation layer, the remaining thickness of the photoresist layer is greater than 1000 angstroms.

[0076] In practical applications, taking the first fluorine-containing gas as trifluoromethane and carbon tetrafluoride, the first auxiliary gas as oxygen, and the second auxiliary gas as hydrogen as an example, under the condition that the gas flow rate of trifluoromethane remains unchanged, within the above corresponding gas flow rate range, if the gas flow rate of carbon tetrafluoride is increased, the flow rate of oxygen is reduced and the flow rate of hydrogen is increased. For example, if the gas flow rate of carbon tetrafluoride is 480sccm, the gas flow rate of oxygen is 210sccm, and the gas flow rate of hydrogen is 10sccm. On the contrary, if the gas flow rate of carbon tetrafluoride is 480sccm, the gas flow rate of oxygen is 190sccm, and the gas flow rate of hydrogen is 20sccm.

[0077] In some embodiments, the passivation layer further includes an etch stop layer, and the etch stop layer is located between the metal layer and the oxide dielectric layer; the method further includes:

[0078] After etching the passivation layer to the etch stop layer, a second etching gas is used to etch the opening area to remove byproducts generated during the etching process.

[0079] In an embodiment, continue as Figure 3 As shown, the passivation layer also includes a nitride oxide dielectric layer 305 and an etch stop layer 306, the oxide dielectric layer 304 is wrapped around the surface of the nitride oxide dielectric layer 305, the etch stop layer 306 and the metal layer 307, the etch stop layer 306 is located between the nitride oxide dielectric layer 305 and the metal layer 307, and the etch stop layer 306 covers the metal layer 307, and the etch stop layer is used to cover and protect the metal layer during the etching of the passivation layer. Exemplarily, the material of the etch stop layer may include but is not limited to TiN (titanium nitride). After etching the passivation layer to the etch stop layer, a second etching gas is used to etch the opening area, and plasma etching post-treatment (PET, Post Etch Treatment) is performed. Since by-products are formed in the process of etching to form the opening area, some by-products will adhere to the opening area under the action of gravity, and the by-products generated in the etching process are removed by performing plasma etching post-treatment on the opening area.

[0080] In some embodiments, the second etching gas includes a second fluorine-containing gas with a low carbon-fluorine ratio and a third auxiliary gas, and the gas flow ratio of the second fluorine-containing gas to the third auxiliary gas is 1:(18-20). The low carbon-fluorine ratio refers to low carbon and fluorine content. Specifically, the fluorine-containing etching gas generally includes CF 4 , CHF 3、 CH 2 F 2 , CH 3 F and other gases with low carbon-fluorine ratios, as well as C 4 F 8 , C 4 F 6 , C 5 F 8 Optionally, the second fluorine-containing gas in the second etching gas is selected from CF 4 , CHF 3 , CH 2 F 2 At least one gas with a low carbon-fluorine ratio, rather than C 4 F 8 Gases with high carbon-fluorine ratios.

[0081] Exemplarily, the gas flow ratio of the second fluorine-containing gas to the third auxiliary gas is 1:(18-20) or any integer or decimal value in the range. Further preferably, in the first etching gas, the gas flow ratio of trifluoromethane to carbon tetrafluoride is 1:19.

[0082] In some embodiments, the second fluorine-containing gas comprises carbon tetrafluoride.

[0083] In some embodiments, the third auxiliary gas includes oxygen.

[0084] In some embodiments, the gas flow rate of the third auxiliary gas is in the range of 1800 sccm to 2000 sccm. The gas flow rate of the third auxiliary gas may be 1800 sccm, 1800 sccm, 1800 sccm, 1800 sccm, 1800 sccm, 1800 sccm, 1800 sccm, etc. Further preferably, the gas flow rate of the first auxiliary gas may be 1900 sccm. Accordingly, the gas flow rate of carbon tetrafluoride contained in the second fluorine-containing gas is in the range of 100 sccm.

[0085] It should be noted that, during the dry etching process, the etching gas in some etching stages may also include, but is not limited to, inert gases such as nitrogen and argon. In addition, compared to the original old process, the dry etching process in this embodiment can only adjust the gas composition and flow rate of the first etching gas and the second etching gas, without adjusting other related etching process parameters in the old process. As an example only, other related etching process parameters may also include: pressure of 50 to 400 mT, RF frequency of 200 to 1000 W, ESC temperature of 15 to 30 ° C, etc.

[0086] This embodiment reduces the active group CF2+ by removing the fluorine-containing gas with a high carbon-fluorine ratio and using the fluorine-containing gas with a low carbon-fluorine ratio. This is because: under the same volume, temperature and pressure conditions, the number of moles of the two gases is the same (the ideal gas state equation PV = nRT). CF 4 and C 4 F 8 The molecules of C and F contain 4 and 8 F atoms respectively. Therefore, although their molar numbers are the same, C 4 F 8 The number of F atoms in the gas is CF 4 The radio frequency electric field will ionize these molecules, and the degree of ionization will depend on factors such as the structure of the molecules, the strength of the electric field, and the temperature. 4 F 8 The number of F atoms in the molecule is CF 4 If the degree of ionization of the two is the same, C 4 F 8 The number of F ions produced will be greater than that of CF 4 .

[0087] The experimental results show that with the reduction of active groups CF2+ in the etching process and the 4The formation of aluminum fluoride polymers can be suppressed. In addition, by increasing the proportion of the first auxiliary gas and the proportion of the third auxiliary gas during the etching process, the newly generated carbon-containing polymer can be removed, solving the problem of polymer defects in the etching process from the source. In this way, by improving the composition and ratio of the etching gas, the problem of polymer defects can be directly solved in one step, and the technical solution has good stability.

[0088] In order to demonstrate the technical effect of the technical solution of the present application, a comparative illustration is provided below in conjunction with comparative examples.

[0089] Comparative Example 1

[0090] In this comparative example 1, the etching gas of the original old process is used to dry-etch the passivation layer on the wafer. Specifically, the etching gas in stage a includes C 4 F 8 , CHF 3 CF 4 and O 2 , excluding H 2 ; The etching gas in stage c includes C 4 F 8 and O 2 Some etching process parameters for dry etching in Comparative Document 1 are shown in Table 1 below:

[0091] Table 1

[0092]

[0093] Among them, stage a refers to the etching stage of the oxide dielectric layer in the passivation layer, stage b refers to the etching stage of the oxynitride dielectric layer in the passivation layer, and stage c refers to the plasma etching post-processing PET stage.

[0094] Example 1

[0095] In Example 1, the first fluorine-containing gas used for etching the oxide dielectric layer is CHF 3 and CF 4 , the first auxiliary gas is O 2 , the second auxiliary gas is H 2 , excluding C 4 F 8 As for the second etching gas, the second fluorine-containing gas with a low carbon-fluorine ratio is CF 4 , the third auxiliary gas is O 2 Some etching process parameters for dry etching in this embodiment are shown in Table 2 below:

[0096] Table 2

[0097]

[0098] Among them, stage a refers to the etching stage of the oxide dielectric layer in the passivation layer, stage b refers to the etching stage of the oxynitride dielectric layer in the passivation layer, and stage c refers to the plasma etching post-processing PET stage.

[0099] Example 2

[0100] The difference from Example 1 is that the gas flow rates of the first etching gas and the second etching gas are different. Some etching process parameters for dry etching in Example 2 are shown in Table 3 below:

[0101] Table 3

[0102]

[0103] Example 3

[0104] The difference from Example 1 is that the gas flow rates of the first etching gas and the second etching gas are different. Some etching process parameters for dry etching in Example 3 are shown in Table 4 below:

[0105] Table 4

[0106]

[0107] Combined with Table 1-4 and Figure 4 It can be seen that compared with the original old process of comparative example 1, the new process in Examples 1-3 removes the fluorine-containing gas C with a high carbon-fluorine ratio in the first etching gas in stage a. 4 F 8 , and increased CF 4 and O 2 At the same time, H is additionally added to the first etching gas. 2 In addition, in stage b, Examples 1-3 also increase the amount of O in the second etching gas. 2 % of.

[0108] After dry etching and cleaning processes, defect detection was performed on Comparative Example 1 and each embodiment. Figure 1 The defect detection result of the wafer formed in Example 1 is shown in FIG. Figure 1 It can be seen from the electron scanning schematic diagram on the left and the optical micrograph of the chip unit on the right that the wafer prepared in Comparative Example 1 contains a large number of polymer defects. Figure 5 is the defect detection result of the wafer formed in Example 1, from Figure 5 The electron scanning schematic diagram on the left and the optical micrograph of the chip unit on the right both indicate that the wafer prepared in Example 1 does not contain polymer defects. In addition, the wafer defect detection results of Examples 2 and 3 also indicate that the wafers do not contain polymer defects.

[0109] In addition, in order to reflect the technical effect of the flow ranges of multiple groups of etching gases used in the embodiments of the present application, the following is an explanation in combination with Reference Example 1 and Reference Example 2.

[0110] The difference between the comparative example 1 and the examples 1-3 is that in stage a, CF 4 The etching gas flow rate is less than 480sccm~520sccm, O 2 The etching gas flow rate is less than 190sccm~210sccm, H 2 The etching gas flow rate is less than 10 sccm to 20 sccm; in stage c, O 2 The etching gas flow rate is less than the range of 1800 sccm to 2000 sccm. Figure 6 Schematic diagram of defect detection results of the wafer prepared in Control Example 1. It can be seen from the figure that when the flow range of the etching gas is lowered, some polymer defects still remain on the prepared wafer.

[0111] The difference between Comparative Example 2 and Examples 1-3 is that in stage a, CF 4 The etching gas flow rate is higher than the range of 480sccm to 520sccm. 2 The etching gas flow rate is higher than the range of 190sccm to 210sccm, H 2 The etching gas flow rate is higher than the range of 10sccm to 20sccm; in stage c, O 2 The etching gas flow rate is higher than the range of 1800 sccm to 2000 sccm. Figure 7 Schematic diagram of defect detection results of the wafer prepared in Control Example 2. It can be seen from the figure that when the flow range of the etching gas is increased, some polymer defects still remain on the prepared wafer.

[0112] The test results show that in stage a, if the first auxiliary gas O 2 If the flow rate of the first auxiliary gas O is less than 190 sccm, new polymer defects may remain. 2 If the flow rate of the second auxiliary gas H is greater than 210 sccm, the etching rate of the photoresist layer will increase, resulting in insufficient protection of the remaining thickness of the photoresist layer. 2 If the flow rate of the second auxiliary gas H is less than 10 sccm, the remaining thickness of the photoresist layer will not be sufficiently protected. 2 If the flow rate is greater than 20 sccm, the photoresist layer will be hardened too much and will be detrimental to the removal of the carbon-containing polymer.

[0113] Some embodiments of the present application also provide a semiconductor device, which is manufactured using any of the above-mentioned methods for manufacturing a semiconductor device.

[0114] Some embodiments of the present application further provide a chip, which includes the semiconductor device described in any of the above embodiments.

[0115] Some embodiments of the present application also provide an electronic device, which includes the semiconductor device and a printed circuit board (PCB) described in any of the above embodiments. The semiconductor device and the printed circuit board are electrically connected to achieve signal communication.

[0116] In some embodiments, the electronic device is, for example, a consumer electronic product, a home electronic product, a car-mounted electronic product, etc. Among them, consumer electronic products are such as mobile phones, tablet computers (pad), laptops, e-readers, personal computers (PC), personal digital assistants (PDA), desktop displays, smart wearable products (e.g., smart watches, smart bracelets), virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, drones, etc. Home electronic products are such as smart door locks, TVs, remote controls, refrigerators, rechargeable small household appliances (e.g., soybean milk machines, sweeping robots), etc. Car-mounted electronic products are such as car navigators, car DVDs, etc. Of course, the electronic device can also be any intermediate product including semiconductor devices. The embodiments of the present application do not impose any special restrictions on the specific form of the above-mentioned electronic devices.

[0117] After the semiconductor device is packaged, it can be used in electronic devices in the form of a chip. Of course, it can also be used directly in electronic devices without packaging.

[0118] The technical effects that can be achieved by the electronic device provided in the embodiments of the present application are the same as the technical effects that can be achieved by the semiconductor device described in any of the above embodiments, and will not be repeated here.

[0119] It should be noted that the above-mentioned sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above-mentioned specific embodiments of this specification are described. Other embodiments are within the scope of the attached claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0120] Each embodiment in the present application is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device, apparatus or equipment embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0121] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a semiconductor device, characterized in that: include: Providing a wafer, on which a metal layer containing aluminum and a passivation layer are formed, the passivation layer is a multi-layer structure sequentially stacked on the metal layer, and the passivation layer includes an oxide dielectric layer; Using multiple sets of etching gases corresponding to the multi-layer structure, etching the passivation layer to form an opening area exposing a portion of the metal layer; performing a cleaning process to at least clean the byproducts in the opening area; The plurality of etching gas groups include a first etching gas for etching the oxide dielectric layer, the first etching gas includes a first fluorine-containing gas with a low carbon-fluorine ratio and a first auxiliary gas, and the first auxiliary gas is used to remove carbon-containing polymers generated during the etching process.

2. The method according to claim 1, characterized in that The first fluorine-containing gas includes trifluoromethane and carbon tetrafluoride; in the first etching gas, the gas flow ratio of trifluoromethane to carbon tetrafluoride is 5:(24-26); And / or, a gas flow rate ratio of the first fluorine-containing gas to the first auxiliary gas is less than 4.

3. The method according to claim 2, characterized in that The first auxiliary gas includes oxygen; In the first etching gas, the gas flow ratio of trifluoromethane to oxygen is 10:(19-21).

4. The method according to claim 3, characterized in that The gas flow rate of carbon tetrafluoride contained in the first fluorine-containing gas is in the range of 480 sccm to 520 sccm, and the gas flow rate of the first auxiliary gas is in the range of 190 sccm to 210 sccm.

5. The method according to any one of claims 1 to 4, characterized in that: A photoresist layer is formed on the passivation layer, and the first etching gas further includes a second auxiliary gas for hardening the photoresist layer; The etching of the passivation layer using a plurality of groups of etching gases corresponding to the multilayer structure comprises: Using the photoresist layer as a mask and the plurality of etching gases, etching the corresponding layer structures in the passivation layer in stages; After etching the passivation layer, the remaining thickness of the photoresist layer is greater than a preset thickness value.

6. The method according to claim 5, characterized in that The second auxiliary gas includes hydrogen, and a gas flow ratio of the second auxiliary gas to the first auxiliary gas is (1-2):(19-21).

7. The method according to claim 5, characterized in that The preset thickness value is greater than or equal to 1000 angstroms.

8. The method according to any one of claims 1 to 4, characterized in that: The passivation layer further includes an etch stop layer, and the etch stop layer is located between the metal layer and the oxide dielectric layer; the method further includes: After etching the passivation layer to the etch stop layer, a second etching gas is used to etch the opening area to remove byproducts generated during the etching process.

9. The method according to claim 8, characterized in that The second etching gas includes a second fluorine-containing gas with a low carbon-fluorine ratio and a third auxiliary gas, and a gas flow ratio of the second fluorine-containing gas to the third auxiliary gas is 1:(18-20).

10. The method according to claim 9, characterized in that The second etching gas satisfies at least one of the following: The second fluorine-containing gas includes carbon tetrafluoride; The third auxiliary gas includes oxygen; The gas flow rate of the third auxiliary gas is in the range of 1800 sccm to 2000 sccm.

11. A semiconductor device, characterized in that: The semiconductor device is manufactured by the method for manufacturing a semiconductor device according to any one of claims 1 to 10.

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