Etching method based on hard mask and semiconductor device

Abstract

The invention provides an etching method based on a hard mask and a semiconductor device. Firstly, a material layer to be etched is provided. Then, a spin-coating carbon layer is manufactured on the to-be-etched material layer, and then an oxide layer is manufactured on the side, away from the to-be-etched material layer, of the spin-coating carbon layer; and then, coating a photoresist layer on one side, far away from the to-be-etched material layer, of the oxide layer, and then, patterning the photoresist layer. The method comprises the following steps: firstly, patterning a photoresist layer, then, etching an oxide layer based on a photoresist window formed after patterning the photoresist layer, then, etching a spin-coating carbon layer based on an oxide layer window formed after etching the oxide layer to form a hard mask, and finally, etching a to-be-etched material layer based on the hard mask. Therefore, according to the scheme, the oxide layer is added between the photoetching layer and the spin-coating carbon layer, so that the pattern morphology after photoetching can be improved, and the conformality of pattern etching transmission is enhanced.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing, and in particular, to a hard mask-based etching method and a semiconductor device. Background Art

[0002] As the complexity of integrated circuit design continues to increase, the requirements for fine patterns are becoming increasingly higher, so it is crucial to use a hard mask to improve the etching selectivity of material features. Currently, when preparing a hard mask, spin-coated carbon is used and coated on the surface of the etched layer, and then a stable spin-coated carbon mask layer is formed through a baking process. Then, a photoresist is coated on the spin-coated carbon mask layer and patterning is performed. However, during the preparation process, the pattern morphology after photoresist patterning is not good, which affects the subsequent pattern etching transfer. Summary of the invention

[0003] In order to overcome the technical problems mentioned in the above technical background, an embodiment of the present application provides an etching method based on a hard mask, the method comprising:

[0004] Providing a material layer to be etched;

[0005] Forming a spin-on carbon layer on the material layer to be etched;

[0006] Forming an oxide layer on a side of the spin-coated carbon layer away from the material layer to be etched;

[0007] Coating a photoresist layer on a side of the oxide layer away from the material layer to be etched;

[0008] patterning the photoresist layer;

[0009] Etching the oxide layer based on the photoresist window formed after patterning the photoresist layer;

[0010] Based on the oxide layer window formed by etching the oxide layer, the spin-on carbon layer is etched to form a hard mask;

[0011] The material layer to be etched is etched based on the hard mask.

[0012] In a possible implementation manner, in the step of etching the oxide layer based on the photoresist window formed after patterning the photoresist layer, the method includes:

[0013] Placing the material to be etched on which the spin-on carbon layer, the oxide layer and the photoresist window are formed on a first substrate in a first etching chamber, wherein the temperature of the first substrate is 20° C. to 40° C.;

[0014] The first etching gas and the second etching gas are controlled according to the pre-configured first upper RF source power and the first lower electrode power to etch the oxide layer of the photoresist window for 10s to 30s to form an oxide layer window.

[0015] In a possible implementation manner, before the step of etching the oxide layer based on the photoresist window formed after patterning the photoresist layer, the method further includes:

[0016] Setting the process pressure range of the first etching chamber to 2 mTorr to 5 mTorr;

[0017] Configure the first upper RF source power and the first lower electrode power of the first etching chamber, and continuously introduce the first etching gas and the second etching gas into the first etching chamber, wherein the first upper RF source power is 300w~700w, the first lower electrode power is 100w~300w, the flow range of the first etching gas is 50sccm~120sccm, the flow range of the second etching gas is 20sccm~40sccm, the first etching gas includes carbon tetrafluoride, and the second etching gas includes argon.

[0018] In a possible implementation, after the step of configuring the process pressure range of the first etching chamber to be 2 mTorr to 5 mTorr, the method further includes:

[0019] A first inert gas is continuously introduced into a side of the first substrate away from the material to be etched, wherein the gas pressure of the first inert gas ranges from 5T to 10T, and the first inert gas includes helium.

[0020] In a possible implementation, in the step of etching the spin-on carbon layer to form a hard mask based on the oxide layer window formed after etching the oxide layer, the method includes:

[0021] Transferring the material to be etched with the spin-coated carbon layer and the oxide layer window formed thereon to a second substrate in a second etching chamber, wherein the temperature of the second substrate is 0° C. to 10° C.;

[0023] The third etching gas and the fourth etching gas are controlled according to the pre-configured second upper RF source power and the second lower electrode power to etch the spin-on carbon layer of the oxide layer window for 60s to 120s to form a hard mask.

[0024] In a possible implementation manner, before the step of etching the spin-on carbon layer to form a hard mask based on the oxide layer window formed after etching the oxide layer, the method further includes:

[0025] The process pressure range of the second etching chamber is configured to be 2 mTorr to 5 mTorr;

[0026] The second upper RF source power and the second lower electrode power of the second etching chamber are configured, and a third etching gas and a fourth etching gas are continuously introduced into the second etching chamber, wherein the second upper RF source power is 200w~500w, the second lower electrode power is 100w~200w, the flow range of the third etching gas is 30sccm~60sccm, the flow range of the fourth etching gas is 10sccm~30sccm, the third etching gas includes oxygen, and the fourth etching gas includes nitrogen.

[0027] In a possible implementation, after the step of configuring the process pressure range of the second etching chamber to be 2 mTorr to 5 mTorr, the method further includes:

[0028] A second inert gas is continuously introduced toward a side of the second substrate away from the material to be etched.

[0029] In a possible implementation manner, in the step of forming a spin-coated carbon layer on the material layer to be etched, the method includes:

[0030] A 130nm-150nm spin-coated carbon layer is coated on the material to be etched by spin coating.

[0031] In a possible implementation, in the step of forming an oxide layer on a side of the spin-coated carbon layer away from the material layer to be etched, the method includes:

[0032] Placing the material to be etched with the spin-on carbon layer in a plasma enhanced chemical vapor deposition chamber;

[0033] A 10nm-30nm oxide layer is grown on a side of the spin-on carbon layer away from the material to be etched, wherein the oxide layer comprises silicon oxide.

[0034] Another object of the present application is to provide a semiconductor device, wherein at least one film layer in the semiconductor device is formed by using any of a plurality of hard mask-based etching methods provided in the present application.

[0035] Based on any of the above aspects, the embodiments of the present application provide a hard mask-based etching method and a semiconductor device. Thus, the above solution can improve the pattern morphology after photolithography and enhance the conformality of pattern etching transfer by adding an oxide layer between the photolithography layer and the spin-on carbon layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 A step diagram of an etching method based on a hard mask provided in this embodiment;

[0038] Figure 2 Figure 1 Corresponding etching process diagram;

[0039] Figure 3 A table showing the relationship between the temperature of the second substrate and the tilt angle of the pattern after the spin-on carbon layer is etched provided in this embodiment;

[0040] Figure 4 A table showing the relationship between nitrogen flow rate and sidewall steepness after spin-on carbon layer etching provided in this embodiment;

[0041] Figure 5 This is a schematic diagram of the oxide layer and the spin-coated carbon layer under a scanning electron microscope after etching is completed in this embodiment.

[0042] Icon: 1-hard mask; 10-material layer to be etched; 20-spin-on carbon layer; 30-oxide layer; 300-oxide layer window; 40-photoresist layer; 400-photoresist window. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0045] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0046] In the description of this application, it should be noted that the terms "upper", "lower", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply 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 on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0047] It should be noted that, in the absence of conflict, different features in the embodiments of the present application may be combined with each other.

[0048] The inventors found that when etching the etched layer using a hard mask (e.g., a spin-coated carbon mask layer), the spin-coated carbon is first applied to the surface of the etched layer by spin coating, and then a stable spin-coated carbon mask layer is formed by a baking process. Then, a photoresist is applied to the spin-coated carbon mask layer, and then the photoresist is patterned, and the spin-coated carbon mask layer is etched based on the photoresist window formed by the photoresist patterning to form a hard mask. However, due to the low bonding force between the photoresist and the spin-coated carbon mask layer, uneven coating is prone to occur during the process of applying the photoresist, which affects the pattern morphology after the photoresist is patterned, and then affects the subsequent pattern transmission.

[0049] In addition, since the spin-coated carbon solution is mainly composed of high molecular polymers, in the subsequent etching step, carbon tetrafluoride, oxygen and other gases are generally used to generate plasma to open the spin-coated carbon mask layer for patterning. Despite the constraints of the external electric field, some plasma groups still react with the pattern sidewalls of the spin-coated carbon mask layer, causing the spin-coated carbon mask layer to have defects such as pattern collapse, top rounding, and line breakage, which again affects the subsequent pattern etching transfer. Therefore, the inventor innovatively designed the following technical solution, and the specific implementation scheme of this application will be described in detail in conjunction with the accompanying drawings.

[0050] See also Figure 1 , Figure 2a and Figure 2b , Figure 1 A step diagram of an etching method based on a hard mask 1 provided in this embodiment, Figure 2a and Figure 2b for Figure 1 Corresponding etching process diagram. The etching method based on the hard mask 1 includes:

[0051] Step S110 , providing a material layer 10 to be etched.

[0052] In this embodiment, the material layer 10 to be etched can be a semiconductor material (such as silicon), a metal material (such as copper, aluminum) or an insulating material (such as silicon dioxide, silicon nitride), etc. The material made of the material to be etched is not specifically limited here and needs to be selected according to actual conditions.

[0053] Step S120 , forming a spin-on carbon layer 20 on the material layer 10 to be etched.

[0054] In this embodiment, the material made of the spin-coated carbon layer 20 is spin-coated carbon (SOC). SOC is a high-carbon polymer solution with a carbon content greater than 80%. It has the characteristics of high etching resistance, few spin-coating defects and low surface roughness, and can protect the material layer 10 to be etched from damage.

[0055] Step S130 , forming an oxide layer 30 on a side of the spin-coated carbon layer 20 away from the material layer 10 to be etched.

[0056] In this embodiment, the oxide layer 30 has good chemical stability and thermal stability. The oxide layer 30 is formed on the spin-coated carbon layer 20 to provide an additional protective layer for the subsequent etching process to prevent the spin-coated carbon layer 20 from being damaged during the etching process. At the same time, since the bonding force between the photoresist layer 40 and the spin-coated carbon layer 20 is relatively low, uneven coating is likely to occur when coating the photoresist layer 40. The oxide layer 30 is used as a buffer layer between the spin-coated carbon layer 20 and the photoresist layer 40 to improve the bonding force between the photoresist layer 40 and the spin-coated carbon layer 20, thereby improving the pattern morphology of the photoresist layer 40 after photolithography, and making the pattern angle steep after photolithography.

[0057] Step S140 , coating a photoresist layer 40 on a side of the oxide layer 30 away from the material layer 10 to be etched.

[0058] Step S150 , patterning the photoresist layer 40 .

[0059] In this embodiment, the photoresist layer 40 is a light-sensitive polymer film that can undergo a chemical reaction under the irradiation of light of a specific wavelength to form a desired pattern. After a layer of photoresist layer 40 is coated on the side of the oxide layer 30 away from the material layer 10 to be etched, the photoresist layer 40 is patterned, and the desired pattern is transferred to the photoresist layer 40 through a photolithography process. The patterning generally includes steps such as exposure and development.

[0060] In step S160 , the oxide layer 30 is etched based on the photoresist window 400 formed after patterning the photoresist layer 40 .

[0061] In this embodiment, the oxide layer 30 under the photoresist window 400 is etched by controlling specific etching conditions and parameters, and the pattern of the photoresist layer 40 is transferred to the oxide layer 30 .

[0062] In step S170 , the spin-on carbon layer 20 is etched based on the oxide layer window 300 formed by etching the oxide layer 30 to form a hard mask 1 .

[0063] In this embodiment, by setting specific etching conditions and parameters, the spin-coated carbon layer 20 under the oxide layer window 300 is etched, and the pattern on the oxide layer 30 is transferred to the spin-coated carbon layer 20. The oxide layer 30 and the spin-coated carbon layer 20 form a hard mask 1. The specific etching conditions and parameters set in this embodiment can increase the steepness of the sidewalls of the spin-coated carbon layer 20 after etching, thereby improving the conformality of the pattern transfer.

[0064] In addition, due to the presence of the oxide layer 30, when the spin-coated carbon layer 20 is etched through the oxide layer window 300, the oxide layer 30 protects the spin-coated carbon layer 20 that is not in the oxide layer window 300, ensuring that the spin-coated carbon layer 20 can be completely etched open and increasing the steepness of the spin-coated carbon layer 20 after etching.

[0065] Step S180 , etching the material layer 10 to be etched based on the hard mask 1 .

[0066] In this embodiment, after the oxide layer 30 and the spin-coated carbon layer 20 form a hard mask 1, the material layer 10 to be etched is etched based on the hard mask 1. The etching of the material layer 10 to be etched can be completed in the first etching chamber, and F-based gas is usually used to etch the material layer 10 to be etched. In this process, the oxide layer 30 will be quickly consumed due to its thin thickness, and a portion of the spin-coated carbon layer 20 will also be consumed. After the etching is completed, the remaining spin-coated carbon layer 20 can be removed by ICP dry etching.

[0067] Further, step S160 can be implemented in the following manner:

[0068] Firstly, a spin-on carbon layer, an oxide layer and a material to be etched with a photoresist window are placed on a first substrate in a first etching chamber, wherein the temperature of the first substrate is 20°C to 40°C.

[0069] In this embodiment, the temperature of the first substrate in the first etching chamber is controlled to be 20°C to 40°C. Exemplarily, the temperature of the first substrate is 20°C, 25°C, 30°C, 35°C and 40°C, etc., to ensure stability during the etching process and controllability of the etching rate.

[0070] Then, the first etching gas and the second etching gas are controlled according to the pre-configured first upper radio frequency source power and the first lower electrode power to etch the oxide layer of the photoresist window for 10s to 30s to form an oxide layer window.

[0071] In the present embodiment, the etching of the oxide layer adopts inductively coupled plasma etching (ICP), and the first upper RF source and the first lower electrode are turned on, so that the first etching gas and the second etching gas form plasma in the first etching chamber, and the active particles in the plasma react with the oxide layer to remove the oxide layer. The first etching gas and the second etching gas etch the oxide layer of the photoresist window for 10s to 30s to form an oxide layer window. Exemplarily, the first etching gas and the second etching gas etch the oxide layer of the photoresist window for 10s, 15s, 20s, 25s and 30s to form an oxide layer window.

[0072] It is worth noting that after turning on the first upper RF source and the first lower electrode, the time for the first upper RF source and the first lower electrode to generate plasma with the first etching gas and the second etching gas is 3s to 5s. Exemplarily, the time for the first upper RF source and the first lower electrode to generate plasma with the first etching gas and the second etching gas is 3s, 4s and 5s, etc.

[0073] Furthermore, before step S160, the method further includes:

[0074] First, the process pressure range of the first etching chamber is configured to be 2 mTorr to 5 mTorr.

[0075] In this embodiment, the process pressure range of the first etching chamber is configured to be 2mTorr to 5mTorr. For example, the process pressure range of the first etching chamber is configured to be 2mTorr, 3mTorr, 4mTorr and 5mTorr, etc., in order to balance the etching rate and etching quality, and avoid excessively high pressure causing a decrease in etching rate or excessively low pressure causing uneven etching. The unit "mTorr" represents micrometers of mercury.

[0076] Next, configure the first upper RF source power and the first lower electrode power of the first etching chamber, and continuously introduce the first etching gas and the second etching gas into the first etching chamber, wherein the first upper RF source power is 300w~700w, the first lower electrode power is 100w~300w, the flow range of the first etching gas is 50sccm~120sccm, the flow range of the second etching gas is 20sccm~40sccm, the first etching gas includes carbon tetrafluoride, and the second etching gas includes argon.

[0077] In this embodiment, the power of the first upper RF source is configured to be 300w-700w, and the power of the first lower electrode is configured to be 100w-300w. By way of example, the power of the first upper RF source is configured to be 300w, 400w, 500w, 600w, and 700w, etc., and the power of the first lower electrode is configured to be 100w, 200w, and 300w, etc. The first upper RF source is mainly used to provide sufficient energy to excite the etching gas (the first etching gas and the second etching gas) to form plasma, and the first lower electrode is mainly used to adjust the distribution of the plasma and the uniformity of etching.

[0078] A first etching gas with a flow rate of 50 sccm to 120 sccm and a second etching gas with a flow rate of 20 sccm to 40 sccm are introduced into the first etching chamber. For example, the first etching gas with a flow rate of 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm, 100 sccm, 110 sccm and 120 sccm and the second etching gas with a flow rate of 20 sccm, 30 sccm and 40 sccm are introduced into the first etching chamber. In addition, the first etching gas includes carbon tetrafluoride (CF4), and the second etching gas includes argon (Ar). CF4 can react chemically with the oxide layer to generate volatile fluoride, thereby removing the oxide layer 30. Argon mainly plays the role of dilution and auxiliary etching. It can adjust the temperature and density of the plasma, thereby improving the uniformity and rate of etching.

[0079] Furthermore, before step S160, the method further includes:

[0080] A first inert gas is continuously introduced into a side of the first substrate away from the material to be etched, wherein the gas pressure of the first inert gas ranges from 5T to 10T, and the first inert gas includes helium.

[0081] In this embodiment, the first inert gas is continuously introduced into the side of the first substrate away from the material to be etched, that is, the back side of the first substrate, mainly to cool down the temperature of this area. The gas pressure range of the first inert gas is 5T to 10T. Exemplarily, the gas pressure range of the first inert gas is 5T, 6T, 7T, 8T, 9T and 10T, etc.

[0082] It is worth noting that the first inert gas is introduced until the etching of the oxide layer is completed.

[0083] Furthermore, step S170 may be implemented in the following manner.

[0084] Firstly, the material to be etched with the spin-coated carbon layer and the oxide layer window is transferred to the second substrate in the second etching chamber, wherein the temperature of the second substrate is 0°C to 10°C.

[0085] In this example, see Figure 3 , Figure 3 The relationship diagram between the temperature of the second substrate and the tilt angle of the pattern after the spin-coated carbon layer is etched is provided in this embodiment. The change of the temperature of the second substrate will affect the tilt angle of the pattern after the spin-coated carbon layer is etched. Therefore, the temperature of the second substrate is controlled to be 0℃~10℃. For example, the temperature of the first substrate is 0℃, 5℃ and 10℃, etc., which can keep the side wall of the spin-coated carbon layer steep after etching, and improve defects such as pattern collapse and top rounding after etching.

[0086] Next, the third etching gas and the fourth etching gas are controlled according to the pre-configured second upper RF source power and the second lower electrode power to etch the spin-on carbon layer of the oxidation window for 60s to 120s to form a hard mask 1.

[0087] In the present embodiment, the etching of the spin-on carbon layer adopts inductively coupled plasma etching (ICP), firstly, the second upper RF source and the second lower electrode are turned on, so that the third etching gas and the fourth etching gas form plasma in the second etching chamber, and the active particles in the plasma react with the spin-on carbon layer to remove the spin-on carbon layer. The third etching gas and the fourth etching gas etch the spin-on carbon layer of the oxide layer window for 60s to 120s to form a hard mask. For example, the third etching gas and the fourth etching gas etch the spin-on carbon layer of the oxide layer window for 60s, 70s, 80s, 90s, 100s, 110s and 120s to form a hard mask.

[0088] It is worth noting that after turning on the second upper RF source and the second lower electrode, the time for the second upper RF source and the second lower electrode to generate plasma with the third etching gas and the fourth etching gas is 3s to 5s. Exemplarily, the time for the second upper RF source and the second lower electrode to generate plasma with the third etching gas and the fourth etching gas is 3s, 4s and 5s, etc.

[0089] Furthermore, before step S170, the method further includes:

[0090] The process pressure range of the second etching chamber is configured to be 2 mTorr to 5 mTorr.

[0091] In this embodiment, the process pressure range of the second etching chamber is configured to be 2mTorr to 5mTorr, in order to balance the etching rate and the etching quality. Exemplarily, the process pressure range of the second etching chamber is configured to be 2mTorr, 3mTorr, 4mTorr and 5mTorr, etc.

[0092] The second upper RF source power and the second lower electrode power of the second etching chamber are configured, and a third etching gas and a fourth etching gas are continuously introduced into the second etching chamber, wherein the second upper RF source power is 200w~500w, the second lower electrode power is 100w~200w, the flow range of the third etching gas is 30sccm~60sccm, the flow range of the fourth etching gas is 10sccm~30sccm, the third etching gas includes oxygen, and the fourth etching gas includes nitrogen.

[0093] In this embodiment, the power of the second upper RF source is configured to be 200w-700w, and the power of the second lower electrode is configured to be 100w-200w. For example, the power of the second upper RF source is configured to be 200w, 300w, 400w, 500w, 600w and 700w, and the power of the second lower electrode is configured to be 100w and 200w, etc. A third etching gas with a flow rate of 30sccm-60sccm and a fourth etching gas with a flow rate of 10sccm-30sccm are introduced into the second etching chamber. For example, a third etching gas with a flow rate of 30sccm, 40sccm, 50sccm and 60sccm and a fourth etching gas with a flow rate of 10sccm, 20sccm and 30sccm are introduced into the second etching chamber. In addition, the third etching gas includes oxygen (O2), and the fourth etching gas includes nitrogen (N2). O2 can chemically react with the oxide layer to generate volatile gas products, thereby achieving an etching effect.

[0094] See also Figure 4 , Figure 4 The relationship between the nitrogen flow rate and the steepness of the side wall of the spin-coated carbon layer after etching provided in this embodiment, the change of nitrogen flow rate will affect the steepness of the side wall of the spin-coated carbon layer after etching. Setting the nitrogen flow rate within a certain range can keep the side wall of the spin-coated carbon layer steep after etching, and improve defects such as pattern collapse and top rounding after etching.

[0095] Furthermore, before step S170, the method further includes:

[0096] The second inert gas is continuously introduced toward a side of the second substrate away from the material to be etched.

[0097] In this embodiment, the second inert gas is continuously introduced into the side of the second substrate away from the material to be etched, that is, the back side of the second substrate, mainly to reduce the temperature of the area. The gas pressure range of the second inert gas can be the same as the gas pressure range of the first inert gas, and the gas pressure range of the second inert gas is 5T to 10T. For example, the gas pressure range of the second inert gas is 5T, 6T, 7T, 8T, 9T and 10T, etc. In addition, the second inert gas can be nitrogen.

[0098] Further, step S120 can be implemented in the following manner.

[0099] A spin-coated carbon layer 20 with a thickness of 130 nm to 150 nm is coated on the material to be etched by spin coating.

[0100] In this embodiment, the spin-coated carbon solution is spin-coated on the material to be etched by a coating machine, and then placed on a substrate for heating and curing to form a spin-coated carbon layer. The thickness of the finally formed spin-coated carbon layer is 130nm to 150nm. For example, the thickness of the spin-coated carbon layer 20 is 130nm, 140nm, 150nm, etc.

[0101] It is worth noting that the spin-coated carbon solution can be cured by heating, baking or ultraviolet irradiation.

[0102] Further, step S130 may be implemented in the following manner.

[0103] Firstly, a material to be etched with a spin-coated carbon layer is placed in a plasma enhanced chemical vapor deposition chamber.

[0104] Then, a 10 nm to 30 nm oxide layer is grown on a side of the spin-coated carbon layer away from the material to be etched, wherein the oxide layer comprises silicon oxide.

[0105] In this embodiment, the material to be etched with a spin-coated carbon layer is placed in a plasma enhanced chemical vapor deposition chamber (PECVD) for growth, and an oxide layer is grown on the side of the spin-coated carbon layer away from the material to be etched by PECVD technology. The final thickness of the oxide layer is 10nm to 30nm. By way of example, the thickness of the oxide layer is 10nm, 20nm, 30nm, etc.

[0106] See also Figure 5 , Figure 5 The morphology of the oxide layer and the spin-coated carbon layer after etching provided in this embodiment under a scanning electron microscope. The oxide layer and the spin-coated carbon layer after etching using a hard mask-based etching method are as follows: Figure 5 As shown, Figure 5 ① represents the spin-coated carbon layer after etching, and ② represents the oxide layer after etching. It can be seen that the sidewall of the spin-coated carbon layer after etching is steep, which improves the defects such as pattern collapse that occur after etching of the spin-coated carbon layer. After etching is completed, the steepness of the sidewall of the spin-coated carbon layer is 85° to 90°. For example, the steepness of the sidewall of the spin-coated carbon layer is 85°, 86°, 87°, 88°, 89° and 90°. In addition, the pattern inclination angle of the spin-coated carbon layer is 85° to 90°. For example, the pattern inclination angle of the spin-coated carbon layer is 85°, 86°, 87°, 88°, 89° and 90°.

[0107] Based on the same inventive concept, another object of the present application is to provide a semiconductor device, wherein at least one film layer in the semiconductor device is formed by any of the aforementioned hard mask-based etching methods. The film layer pattern formed by the hard mask-based etching method is steep, which is conducive to the pattern transfer of subsequent film layers in the semiconductor device.

[0108] In summary, the present application provides an etching method and semiconductor device based on a hard mask. First, a material layer to be etched is provided. Then, a spin-coated carbon layer is made on the material layer to be etched, and then, an oxide layer is made on the side of the spin-coated carbon layer away from the material layer to be etched. Then, a photoresist layer is coated on the side of the oxide layer away from the material layer to be etched, and then, the photoresist layer is patterned. Then, the oxide layer is etched based on the photoresist window formed after patterning the photoresist layer, and then, based on the oxide layer window formed after etching the oxide layer, the spin-coated carbon layer is etched to form a hard mask, and finally, the material layer to be etched is etched based on the hard mask. In this way, the above scheme can improve the pattern morphology after photolithography and enhance the conformality of pattern etching transfer by adding an oxide layer between the photolithography layer and the spin-coated carbon layer.

[0109] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A hard mask based etching method, characterized in that: The method comprises: Providing a material layer to be etched; Forming a spin-on carbon layer on the material layer to be etched; Forming an oxide layer on a side of the spin-coated carbon layer away from the material layer to be etched; Coating a photoresist layer on a side of the oxide layer away from the material layer to be etched; patterning the photoresist layer; Etching the oxide layer based on the photoresist window formed after patterning the photoresist layer; Based on the oxide layer window formed by etching the oxide layer, the spin-on carbon layer is etched to form a hard mask; The material layer to be etched is etched based on the hard mask.

2. The hard mask based etching method according to claim 1, characterized in that: In the step of etching the oxide layer based on the photoresist window formed after patterning the photoresist layer, the method comprises: Placing the material to be etched on which the spin-on carbon layer, the oxide layer and the photoresist window are formed on a first substrate in a first etching chamber, wherein the temperature of the first substrate is 20° C. to 40° C.; The first etching gas and the second etching gas are controlled according to the pre-configured first upper RF source power and the first lower electrode power to etch the oxide layer of the photoresist window for 10s to 30s to form an oxide layer window.

3. The hard mask based etching method according to claim 2, characterized in that: Before the step of etching the oxide layer based on the photoresist window formed after patterning the photoresist layer, the method further comprises: Setting the process pressure range of the first etching chamber to 2 mTorr to 5 mTorr; Configure the first upper RF source power and the first lower electrode power of the first etching chamber, and continuously introduce the first etching gas and the second etching gas into the first etching chamber, wherein the first upper RF source power is 300w~700w, the first lower electrode power is 100w~300w, the flow range of the first etching gas is 50sccm~120sccm, the flow range of the second etching gas is 20sccm~40sccm, the first etching gas includes carbon tetrafluoride, and the second etching gas includes argon.

4. The hard mask based etching method according to claim 3, characterized in that: After the step of configuring the process pressure range of the first etching chamber to be 2 mTorr to 5 mTorr, the method further includes: A first inert gas is continuously introduced into a side of the first substrate away from the material to be etched, wherein the gas pressure of the first inert gas ranges from 5T to 10T, and the first inert gas includes helium.

5. The hard mask based etching method according to claim 1, characterized in that: In the step of etching the spin-on carbon layer to form a hard mask based on the oxide layer window formed after etching the oxide layer, the method includes: Transferring the material to be etched with the spin-coated carbon layer and the oxide layer window formed thereon to a second substrate in a second etching chamber, wherein the temperature of the second substrate is 0° C. to 10° C.; The third etching gas and the fourth etching gas are controlled according to the pre-configured second upper RF source power and the second lower electrode power to etch the spin-on carbon layer of the oxide layer window for 60s to 120s to form a hard mask.

6. The hard mask based etching method according to claim 5, characterized in that: Before the step of etching the spin-on carbon layer to form a hard mask based on the oxide layer window formed after etching the oxide layer, the method further includes: The process pressure range of the second etching chamber is configured to be 2 mTorr to 5 mTorr; The second upper RF source power and the second lower electrode power of the second etching chamber are configured, and a third etching gas and a fourth etching gas are continuously introduced into the second etching chamber, wherein the second upper RF source power is 200w~500w, the second lower electrode power is 100w~200w, the flow range of the third etching gas is 30sccm~60sccm, the flow range of the fourth etching gas is 10sccm~30sccm, the third etching gas includes oxygen, and the fourth etching gas includes nitrogen.

7. The hard mask based etching method according to claim 6, characterized in that: After the step of configuring the process pressure range of the second etching chamber to be 2 mTorr to 5 mTorr, the method further includes: A second inert gas is continuously introduced toward a side of the second substrate away from the material to be etched.

8. The hard mask based etching method according to claim 1, characterized in that: In the step of forming a spin-coated carbon layer on the material layer to be etched, the method comprises: A 130nm-150nm spin-coated carbon layer is coated on the material to be etched by spin coating.

9. The hard mask based etching method according to claim 1, characterized in that: In the step of forming an oxide layer on a side of the spin-coated carbon layer away from the material layer to be etched, the method comprises: Placing the material to be etched with the spin-on carbon layer in a plasma enhanced chemical vapor deposition chamber; A 10nm-30nm oxide layer is grown on a side of the spin-on carbon layer away from the material to be etched, wherein the oxide layer comprises silicon oxide.

10. A semiconductor device, characterized in that: At least one film layer in the semiconductor device is formed by the hard mask-based etching method according to any one of claims 1 to 9.

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