Metal layer etching method and semiconductor process equipment

Abstract

The invention discloses a metal layer etching method and semiconductor process equipment, and relates to the field of semiconductor processes and equipment. The metal layer etching method comprises the steps that a first etching step is executed, first etching gas is introduced into a reaction chamber to etch a metal layer, a nitride layer is arranged below the metal layer, and the nitride layer makes contact with the metal layer; the spectral intensity of a CN spectral signal is detected, when the spectral intensity is accelerated, a second etching step is executed, second etching gas is introduced into the reaction chamber to etch the residual metal layer and nitride layer, the second etching gas contains C element, and the C element is introduced into the reaction chamber to etch the residual metal layer and nitride layer; the C element is used for forming a CN chemical group with an N element in the nitride layer. The problem that an end point detection method in the prior art is difficult to capture an etching end point can be solved.

Description

Technical Field

[0001] The present application belongs to the technical field of semiconductor processes and equipment, and specifically relates to a metal layer etching method and semiconductor process equipment. Background Art

[0002] In the field of integrated circuit manufacturing, plasma etching is a commonly used process method, which can be further divided into silicon etching, dielectric etching and metal etching according to the material being etched. Although driven by Moore's Law (the number of transistors integrated in integrated circuits has increased by millions of times, and the feature size of devices has also increased from micron level to submicron level and then to the current nanometer level), people have replaced aluminum with copper with lower resistivity and introduced materials with low dielectric constants to reduce parasitic capacitance in the circuit to solve the RC delay circuit effect problem faced by electronic devices when the feature size of the device becomes smaller, and copper is difficult to be etched by plasma, so the metal etching process has gradually withdrawn and replaced by the Damascus process. However, due to the low cost and mature process of aluminum process, metal etching still has a large market in some pan-semiconductor fields such as special devices and discrete devices.

[0003] In a typical device that requires metal etching process, a layer of Ti / TiN film, also called barrier layer, needs to be deposited by sputtering under the metal layer (usually aluminum or aluminum-copper alloy) to prevent metal atoms from diffusing into the silicon wafer below. After depositing the metal on the barrier layer, another layer of Ti / TiN film, also called anti-reflection layer, needs to be deposited to prevent light from interfering with the incident light after reflection and causing abnormal exposure in the subsequent photolithography process.

[0004] Based on this, in metal etching, it is generally necessary to etch the Ti / TiN film first, then etch the metal, and finally etch another layer of Ti / TiN film. Since the chlorine-based gas used to etch the metal and Ti / TiN film also etches the silicon substrate, it is necessary to monitor the etching endpoint so that the etching stops after the second layer of Ti / TiN film is etched. However, when the aperture ratio of the device is small, the change between the reactants and the products in the chamber is not large, which makes it difficult for the endpoint detection method in the related art to capture the etching endpoint. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide a metal layer etching method and semiconductor process equipment, which can solve the problem that the endpoint detection method in the related art is difficult to capture the etching endpoint.

[0006] In order to solve the above technical problems, this application is implemented as follows:

[0007] The present application provides a metal layer etching method, the metal layer etching method comprising:

[0008] Performing a first etching step, introducing a first etching gas into the reaction chamber to etch the metal layer, wherein a nitride layer is disposed below the metal layer and the nitride layer is in contact with the metal layer;

[0009] The spectral intensity of the CN spectral signal is detected. When the increase rate of the spectral intensity is accelerated, a second etching step is performed, and a second etching gas is introduced into the reaction chamber to etch the remaining metal layer and the nitride layer. The second etching gas contains C element, and the C element is used to form a CN chemical group with the N element in the nitride layer.

[0010] The embodiment of the present application further provides a semiconductor process equipment for etching a metal layer, the semiconductor process equipment comprising a reaction chamber and a secondary ignition chamber, the outlet end of the reaction chamber is sequentially connected to a first gas pumping device and a second gas pumping device, the secondary ignition chamber is arranged between the first gas pumping device and the second gas pumping device;

[0011] The semiconductor process equipment further includes a spectrum signal detection device, which is opposite to the window of the secondary ignition chamber and is used for detecting the spectrum signal in the secondary ignition chamber through the window.

[0012] In the embodiment of the present application, the carbon element in the carbon-containing etching gas reacts with the nitrogen element in the nitride layer to form a CN chemical group, and the CN chemical group is used as a marker to indicate the etching endpoint. Compared with the endpoint detection method in the related art, the method of indicating the etching endpoint using the CN chemical group in the embodiment of the present application can improve the indication sensitivity, make the etching endpoint easier to capture, and can be applied to devices with smaller aperture ratios, thereby improving the applicability of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic diagram of the structure of a first form of semiconductor process equipment disclosed in an embodiment of the present application;

[0014] Figure 2 A schematic diagram of the structure of a second form of semiconductor process equipment disclosed in an embodiment of the present application;

[0015] Figure 3 A comparative schematic diagram of using a CN spectrum signal at 387 nanometers to indicate an etching endpoint disclosed in an embodiment of the present application;

[0016] Figure 4 A comparative schematic diagram of the use of TiCl spectral signals at 419 nanometers to indicate the etching endpoint disclosed in the related art;

[0017] Figure 5 This is a schematic diagram of the structure of the semiconductor structure disclosed in the embodiment of the present application.

[0018] Description of reference numerals:

[0019] 110-reaction chamber; 120-secondary ignition chamber; 121-ignition cavity; 122-parallel plate capacitor;

[0020] 210 - first air extraction device; 220 - second air extraction device;

[0021] 310-first RF power source; 320-second RF power source; 330-third RF power source;

[0022] 410 - first radio frequency matching device; 420 - second radio frequency matching device; 430 - third radio frequency matching device;

[0023] 510-first pipeline; 520-second pipeline;

[0024] 610-upper electrode; 620-lower electrode;

[0025] 710- Spectral signal detection device. DETAILED DESCRIPTION

[0026] 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 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 creative work are within the scope of protection of this application.

[0027] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0028] The embodiments of the present application are described in detail below through specific embodiments and their application scenarios in conjunction with the accompanying drawings.

[0029] In the related art, for conventional metal etching, such as aluminum etching, Al 396nm or AlCl261nm is generally used, and when titanium nitride is included, Ti 365nm or TiCl 419nm is used. When aluminum / titanium nitride reaches the etching end point, these characteristic products disappear along with the disappearance of the reactants, thereby judging the etching end point.

[0030] The disadvantages of the above judgment method are: 1. Different chromophores have different luminescence efficiencies. When the etching opening rate becomes lower, the concentration of the characteristic product becomes lower. When the luminescence efficiency of the chromophore is also relatively low, it cannot be detected; 2. The above wavelengths do not necessarily correspond uniquely to the chromophore. For example, the 419nm at which TiCl is located can also be the emission of the O element. Therefore, different markers may interfere with each other.

[0031] Due to the above shortcomings, for a certain etching, finding a suitable endpoint detection marker is not a process that can be achieved without creative labor. For example, for W etching, people found that the best endpoint detection marker is not the product containing W, but the reactant F that monitors the etching of tungsten. When the emission spectrum of F is enhanced, it means that W has been exhausted, thus indicating the etching endpoint.

[0032] Back to the present invention, the advantage of using CN is that there is no interference from the emission of other markers at 387nm, and CN has high emission efficiency and good intensity, and is easy to be identified by endpoint monitoring.

[0033] Based on the above situation, an embodiment of the present application proposes a method for indicating the etching endpoint by detecting CN to improve the indication sensitivity and make the etching endpoint easier to capture, so that it can be applicable to devices with smaller aperture ratios, thereby improving the applicability of the process.

[0034] refer to Figures 1 to 3 The embodiment of the present application discloses a metal layer etching method, which can be applied to integrated circuit manufacturing scenarios. Of course, it can also be applied to other scenarios, which are not specifically limited here. The disclosed metal layer etching method includes:

[0035] Performing a first etching step, introducing a first etching gas into the reaction chamber 110 to etch the metal layer, wherein a nitride layer is disposed below the metal layer and the nitride layer is in contact with the metal layer;

[0036] Detect the spectral intensity of the CN spectral signal. When the spectral intensity increases, execute

[0037] In the second etching step, a second etching gas is introduced into the reaction chamber 110 to etch the remaining metal layer and the nitride layer. The second etching gas contains a C element, which is used to form a CN chemical group with the N element in the nitride layer. Thus, the etching endpoint of the metal layer and the nitride layer can be indicated by the CN chemical group.

[0038] In the embodiment of the present application, the carbon element in the carbon-containing etching gas reacts with the nitrogen element in the nitride layer to form a CN chemical group, and the CN chemical group is used as a marker to indicate the etching endpoint. Compared with the endpoint detection method in the related art, the method of indicating the etching endpoint using the CN chemical group in the embodiment of the present application can improve the indication sensitivity, make the etching endpoint easier to capture, and can be applied to devices with smaller aperture ratios, thereby improving the applicability of the process.

[0039] refer to Figure 5 In some embodiments, the semiconductor structure may further include a substrate, the nitride layer and the metal layer are both provided on the substrate, and the metal layer is separated from the surface of the substrate by the nitride layer. In addition, a film structure may be deposited on the upper surface of the metal layer (i.e., the surface on the side facing away from the nitride layer), and the film structure serves as an anti-reflection layer to prevent the incident light from interfering after light reflection and causing abnormal exposure in the subsequent photolithography process. Exemplarily, the film structure may be a Ti film, or a TiN film, etc. In the actual etching process, the film structure is etched first, then the metal layer, and finally the nitride layer.

[0040] For example, in a device using a metal etching process, a nitride layer may be deposited on the lower surface of the metal layer by sputtering. The nitride layer may serve as a barrier layer to prevent metal atoms from diffusing into a substrate disposed below the nitride layer.

[0041] In some embodiments, the material of the nitride layer may include TiN. Of course, it may also be other materials. The material of the nitride layer is not specifically limited here.

[0042] The second etching gas may be a fluorine-free gas; in addition to this method, the second etching gas may include a carbon-containing gas and a chlorine-containing gas, wherein the carbon-containing gas may include at least one of methane, carbon tetrachloride or aliphatic halogenated hydrocarbons.

[0043] In addition to using carbon-containing gas to introduce carbon, the photoresist carried by the wafer itself can also be used to introduce carbon. Of course, considering that when the thickness of the metal layer reaches a certain level, a hard mask needs to be used due to the problem of photoresist selectivity, at this time, the better way is to use carbon-containing gas to introduce carbon.

[0044] Based on the above-mentioned etching object, the etching process formula can be: the second etching gas includes not only the carbon-containing gas, but also chlorine, boron trichloride and nitrogen, wherein the flow rate of the carbon-containing gas can be 1 to 500 sccm, the flow rate of the chlorine gas can be 1 to 1000 sccm, the flow rate of the boron trichloride can be 1 to 1000 sccm, and the flow rate of the nitrogen can be 1 to 800 sccm.

[0045] In addition, the first etching gas may include argon, chlorine and boron trichloride, wherein the flow rate of argon may be 1-1000 sccm, the flow rate of chlorine may be 1-1000 sccm, and the flow rate of boron trichloride may be 1-1000 sccm.

[0046] In some embodiments, the metal layer may include aluminum. In this case, the metal layer is an aluminum layer. Accordingly, the first etching gas may include a chlorine-containing gas; in addition, the second etching gas may be a fluorine-free gas. It should be noted that, since aluminum etching may produce aluminum fluoride that is difficult to volatilize if it encounters fluorine, when the metal layer includes aluminum, it should be avoided as much as possible to introduce fluorine while introducing carbon.

[0047] Based on the above situation, when the material of the metal layer includes aluminum, the second etching gas can be methane, carbon tetrachloride vapor, fluorine-free aliphatic halogenated hydrocarbons, such as methyl chloride, dichloromethane vapor, chloroform vapor, methyl bromide, dibromomethane vapor, bromoform vapor, monobromochloromethane vapor, monobromodichloromethane vapor, iodomethane vapor, diiodomethane vapor, bromochloroiodomethane vapor, ethyl chloride, dichloroethane vapor, ethyl bromide vapor, dibromoethane vapor, ethyl iodide vapor, propyl chloride vapor, propyl bromide vapor, propyl iodide vapor, butyl chloride vapor, etc. Of course, other types are also possible, which are not specifically limited here.

[0048] Taking the etching of aluminum as an example, the corresponding nitride layer can be a titanium nitride layer (TiN). Since there is a TiN layer under the aluminum layer, it is found in the actual exploration process that after the carbon element is introduced into the etching system, the CN chemical group can be used as a marker (corresponding to the spectrum at 387nm) to indicate the etching end point.

[0049] For the above etching process, the plasma etching process recipe can be found in Table 1.

[0050] Table 1 Plasma etching process recipe

[0051]

[0052]

[0053] In other embodiments, the material of the metal layer may also include tungsten, and the material of the nitride layer may include TiN. Accordingly, the first etching gas may include a chlorine-containing gas. In addition, the second etching gas may include a carbon-containing gas, and the carbon-containing gas includes at least one of methane, carbon tetrachloride, or aliphatic halogenated hydrocarbons. Among them, the aliphatic halogenated hydrocarbon may be a fluorine-containing aliphatic halogenated hydrocarbon or a fluorine-free aliphatic halogenated hydrocarbon, which may be selected according to actual working conditions.

[0054] Based on the above-mentioned etching object, the etching process formula can be: the second etching gas includes not only the carbon-containing gas, but also chlorine, boron trichloride and nitrogen, wherein the flow rate of the carbon-containing gas can be 1 to 500 sccm, the flow rate of the chlorine gas can be 1 to 1000 sccm, the flow rate of the boron trichloride can be 1 to 1000 sccm, and the flow rate of the nitrogen can be 1 to 800 sccm.

[0055] Accordingly, the first etching gas may include argon and sulfur hexafluoride. Of course, other gases may also be included, and the specific types are not limited.

[0056] Among them, in the first etching gas, the flow rate of argon gas can be 1 to 1000 sccm, and the flow rate of sulfur hexafluoride can be 1 to 1000 sccm.

[0057] In some embodiments, the upper electrode power of the first etching step may be greater than the upper electrode power of the second etching step, and the lower electrode power of the first etching step may be greater than the lower electrode power of the second etching step.

[0058] In addition, the pressure in the reaction chamber 110 in the first etching step may be greater than the pressure in the reaction chamber 110 in the second etching step.

[0059] Exemplarily, the process recipe of the first etching step includes: the power range of the upper electrode 610 can be 100-10000 W, the power range of the lower electrode 620 can be 0-1000 W, and the pressure range in the reaction chamber 110 can be 5-50 mTorr.

[0060] The process parameters of the second etching step include: the power range of the upper electrode 610 can be 100-10000 W, the power range of the lower electrode 620 can be 0-1000 W, and the pressure range in the reaction chamber 110 can be 3-30 mTorr.

[0061] Considering that the second etching step includes the first etching stage and the second etching stage, and the first etching stage is used to etch the residual metal layer and the nitride layer, and the second etching stage is used to etch the nitride layer, however, the residual metal layer after etching by the first etching step is less, so that the etching object of the second etching step is mainly the nitride layer, and there is only a small amount of metal layer. Therefore, when performing the first etching stage and the second etching stage, the process formula used in the two etching stages can be made the same, in this case, the complexity of executing the process formula can be reduced, and the etching process requirements can also be met.

[0062] For the above etching process, the plasma etching process recipe can be found in Table 2.

[0063] Table 2 Plasma etching process recipe

[0064]

[0065]

[0066] refer to Figure 3 The metal layer etching method includes a first etching step and a second etching step, wherein the first etching step is used to etch the metal layer, and the second etching step is used to etch the residual metal layer and the nitride layer. In addition, during the etching process, the spectral intensity of the CN spectral signal is used to display the content of the CN chemical group, and the spectral intensity of the CN spectral signal is used to characterize the etching condition.

[0067] The CN spectrum signal of the first etching step is stable in the region at the first spectrum intensity value, and at the end of the first etching step, the growth rate of the spectrum intensity is accelerated.

[0068] It should be noted here that, during the etching process of the metal layer, since the content of nitrogen in the reaction chamber 110 remains basically unchanged or fluctuates within a certain range, even if the second etching gas containing carbon is introduced into the reaction chamber 110, the CN chemical group formed by the carbon and nitrogen elements will not be increased. Therefore, during detection, the spectral intensity of the wavelength of the CN chemical group will not be increased. This is reflected in the spectral curve. During the etching process of the metal layer, the spectral curve is basically in a stable state without obvious fluctuations.

[0069] Of course, it is not ruled out that the nitrogen content in the reaction chamber 110 is accidentally increased or decreased, resulting in a slight increase or decrease in the CN chemical group, which is reflected in the spectrum curve. During the metal layer etching process, the spectrum curve fluctuates within the first preset range.

[0070] When the spectral intensity is detected to increase faster, it indicates that the first etching step is finished. Specifically, when the spectral intensity is detected to increase rapidly from the first intensity value to the second intensity value, that is, when the local formation of the spectral curve presents a large slope, it indicates that the first etching step of the metal layer is finished and the second etching step is started.

[0071] Considering that the first etching step does not completely etch the metal layer, a portion of the residual metal layer remains, so the second etching step needs to etch the residual metal layer and the nitride layer.

[0072] In an embodiment of the present application, the second etching step may include a first etching stage and a second etching stage, wherein the first etching stage is used to etch the residual metal layer and the nitride layer, and the second etching stage is used to etch the residual nitride layer.

[0073] It should be noted here that after the metal layer is almost etched, the nitride layer begins to be etched, which causes the nitrogen content in the reaction chamber 110 to increase instantaneously and react with the carbon element in the second etching gas, thereby forming a large number of CN chemical groups in the reaction chamber 110, which is reflected in the spectral curve. After the metal layer is etched, a large deformation portion will appear in the spectral curve, and accordingly, the slope of the large deformation portion is larger.

[0074] For example, after the metal etching is completed, the spectral intensity can be rapidly enhanced from the first intensity value to the second intensity value, wherein the enhancement amplitude can be within the range of 15% to 30%, such as 15%, 20%, 25%, 30%, etc. For example, the first intensity value can be 1900, and the second intensity value can be 2400. In this case, the enhancement amplitude of the spectral intensity is 26.3%. Of course, it can also be other values, which are not specifically limited here.

[0075] In some embodiments, the spectral intensity region of the CN spectral signal at the end of the first etching stage is stable, the spectral intensity of the CN spectral signal at the end of the second etching stage drops rapidly, or the second etching stage begins to drop and then is delayed for a predetermined time as the end point.

[0076] In addition, the CN spectrum signal in the first etching stage is regionally stable at the second spectrum intensity value, and the CN spectrum signal in the second etching stage is regionally stable at the third spectrum intensity value, and the third spectrum intensity value is smaller than the second spectrum intensity value.

[0077] Specifically, when the nitride layer is etched, the spectral intensity of the wavelength corresponding to the CN chemical group is stable in the area at the second intensity value. It should be noted here that in the process of etching the nitride layer, the content of the nitrogen element in the reaction chamber 110 increases rapidly, and a large amount of nitrogen elements react with the carbon element in the second etching gas to form a large number of CN chemical groups. Therefore, during detection, the spectral intensity of the wavelength of the CN chemical group will be rapidly enhanced, which is reflected in the spectrum curve. During the etching process of the nitride layer, a large deformation portion will appear in the spectrum curve. Then, since the etching speed is basically unchanged, the generation speed of the nitrogen element is basically unchanged, so that the spectral intensity of the wavelength of the CN chemical group is basically unchanged, which is reflected in the spectrum curve. During the etching process of the nitride layer, the spectrum curve is basically in a stable state without obvious fluctuations.

[0078] Of course, it is not ruled out that the nitrogen content in the reaction chamber 110 is accidentally increased or decreased, or the etching speed fluctuates. The nitrogen fluctuates, which is reflected in the spectrum curve. During the nitride layer etching process, the spectrum curve fluctuates within the second preset range.

[0079] When it is detected that the spectrum intensity is greatly reduced, that is, when the local formation of the spectrum curve presents a large slope, it indicates that the nitride layer is completely etched. At this time, the second etching step is completed and the process stops.

[0080] Therefore, the embodiment of the present application takes into account that during the etching process of the metal layer, the etching speeds at different positions are different. For example, generally speaking, for the entire wafer, the etching speed in the center area is slower, while the etching speed in the edge area is faster. Of course, for a specific etching structure, such as a groove, the etching rate in the center of the groove will be faster than the etching rate at the edge of the groove. In this way, the etching of the center area of ​​the metal layer is completed, while the etching of the edge area is not completed. In the embodiment of the present application, a portion of the metal layer can be etched by introducing a first etching gas into the reaction chamber 110.

[0081] Similarly, considering that during the etching of the nitride layer, the etching speeds at different positions are different, for example, the etching speed of the central area of ​​the nitride layer is faster, while the etching speed of the edge area is slower, this will cause the central area of ​​the nitride layer to be completely etched, while the edge area is not completely etched. In addition, since the remaining part of the metal layer is not etched when the metal layer is etched in the first etching step, in the second etching step, by introducing the second etching gas into the reaction chamber 110, the remaining part of the metal layer can be etched by the second etching gas, and the nitride layer can be etched. Based on this, the residual metal layer and part of the nitride layer can be etched through the first etching stage, and the remaining part of the nitride layer can be etched through the second etching stage, thereby ensuring that the nitride layer is completely etched.

[0082] In addition, during the actual etching process of the nitride layer, the etching speeds of different regions are different, resulting in a part of the nitride layer (such as the central region, etc.) having been completely etched, while the remaining other part of the region (such as the edge region, etc.) has not been etched. Based on this, when a part of the nitride layer (i.e., most of the region) is etched, the nitrogen element generated is relatively sufficient, so that the nitrogen content in the reaction chamber 110 is relatively large. In this case, the nitrogen element can fully react with the carbon element in the second etching gas to form more CN chemical groups. During this process, the spectrum intensity obtained by detection is the second intensity value, which is reflected in the spectrum curve. The spectrum curve tends to be stable at the second intensity value, or fluctuates within a small range.

[0083] When another part of the nitride layer (i.e., a small part of the area) is etched, that is, in the second etching stage, the generated nitrogen element is slightly reduced, so that the nitrogen content in the reaction chamber 110 is slightly reduced. In this case, the nitrogen element reacts more fully with the carbon element in the second etching gas to form relatively more CN chemical groups. During this process, the spectrum intensity obtained by detection is the third intensity value, and the third intensity value is slightly reduced compared to the second intensity value; it is reflected in the spectrum curve, the spectrum curve slightly drops from the second intensity value to the third intensity value, and tends to be stable at the third intensity value, or fluctuates within a small range.

[0084] For example, during the etching of the nitride layer, the spectral intensity may be slowly weakened from the second intensity value to the third intensity value, wherein the weakening amplitude may be within the range of 3% to 6%, such as 3%, 4%, 5%, 6%, etc. For example, the second intensity value may be 2400, and the third intensity value may be 2300. In this case, the weakening amplitude of the spectral intensity is 4.17%. Of course, it may be other values, which are not specifically limited here.

[0085] After the etching of the nitride layer is completed, when the spectrum intensity weakens to the fourth intensity value, it indicates that the etching process is stopped, wherein the fourth intensity value is less than the first intensity value. It should be noted here that when the etching of the nitride layer is completed, in order to avoid over-etching and etching to the substrate, the etching process needs to be stopped. At this time, various process conditions in the process formula are stopped, such as stopping power supply, stopping gas supply, etc. After the etching process is stopped, the second etching gas containing the C element is no longer introduced into the reaction chamber 110, and the nitrogen element is no longer generated by etching the nitride layer, so that no new CN chemical groups are formed in the reaction chamber 110.

[0086] After the etching process stops, the plasma glow disappears, causing the detected spectral intensity to suddenly weaken, which is reflected in the spectral curve. The spectral curve suddenly drops to a fourth intensity value after the etching process stops, and the fourth intensity value is much smaller than the third intensity value and also much smaller than the first intensity value.

[0087] In addition, at the moment when the second etching step stops, the spectrum curve forms a sharp point. The reason is that in the process of stopping the process, each process recipe can be gradually stopped, such as stopping the RF power supply, stopping ventilation, etc., and there is a sequence in the stopping of each process recipe. When a part of the process recipe is stopped, it will instantly affect the environment in the reaction chamber 110, thereby causing an instantaneous impact on the content of CN chemical groups in the reaction chamber 110, and finally leading to the formation of a sharp point.

[0088] In the present embodiment, the CN spectrum signal at 387 nanometers is used to indicate the etching end point. The obtained spectrum curve is as follows: Figure 3 In addition, the related art uses the TiCl spectral signal at 419 nm to indicate the etching end point, and the obtained spectral curve is as shown in FIG. Figure 4 As shown. Figure 3 and Figure 4 It can be seen that when the TiCl spectral signal at 419 nanometers is used to indicate the etching end point, the spectral curve does not have obvious fluctuations at the etching end point, resulting in relatively poor sensitivity in grasping the etching end point; while the present application uses the CN spectral signal at 387 nanometers to indicate the etching end point, forming relatively obvious fluctuations at the completion of each etching step, thereby making the grasping of the etching end point more sensitive.

[0089] refer to Figures 1 to 3 The embodiment of the present application also discloses a semiconductor process equipment for etching a metal layer, wherein the disclosed semiconductor process equipment includes a reaction chamber 110 and a secondary ignition chamber 120, wherein the outlet end of the reaction chamber 110 is sequentially connected with a first gas pumping device 210 and a second gas pumping device 220, and the secondary ignition chamber 120 is disposed between the first gas pumping device 210 and the second gas pumping device 220. Exemplarily, the first gas pumping device 210 may be a molecular pump, and the second gas pumping device 220 may be a mechanical pump.

[0090] In addition, the semiconductor process equipment may further include a spectrum signal detection device 710 , which is opposite to the window of the secondary ignition chamber 120 and is used to detect the spectrum signal in the secondary ignition chamber 120 through the window.

[0091] Compared with the method in the related art where the suction part directly sucks the gas in the chamber, the embodiment of the present application sets the secondary ignition chamber 120 between the first exhaust device 210 and the second exhaust device 220, so that the chamber pressure in the secondary ignition chamber 120 is higher, which can bring a more sensitive technical effect of indicating the etching end point, and can be applied to etching with a small opening ratio (e.g., less than 10%). The higher chamber pressure in the secondary ignition chamber 120 can sensitively distinguish when the product concentration changes slightly, thereby improving the accuracy of indicating the etching end point. In addition, since the chamber pressure in the secondary ignition chamber 120 is relatively high (about the order of several hundred millitorr), it can also help ignition.

[0092] In some embodiments, the secondary ignition chamber 120 may use a capacitively coupled plasma processing device, which includes a ignition cavity 121 and a parallel plate capacitor 122, wherein the parallel plate capacitor 122 is disposed in the ignition cavity 121, and the parallel plate capacitor 122 is used to connect to a radio frequency power supply. The capacitively coupled plasma processing device can increase the cavity pressure in the ignition cavity 121, which is helpful for ignition.

[0093] In the embodiment of the present application, the pressure in the secondary ignition chamber 120 may range from 100 mTorr to 1000 mTorr, which may be set according to the process requirements. In addition, other pressure values ​​may be used, which are not specifically limited here.

[0094] In order to alleviate the risk of plasma entering the downstream first exhaust device 220 and causing damage to the second exhaust device 220, in the embodiment of the present application, the first exhaust device 210 is connected to the inlet of the secondary ignition chamber 120 through a first pipe 510, and the outlet of the secondary ignition chamber 120 is connected to the second exhaust device 220 through a plurality of second pipes 520 arranged side by side, and the diameter of the second pipe 520 is smaller than the diameter of the first pipe 510. Through this arrangement, the secondary ignition chamber 120 and the second exhaust device 220 are connected by a second pipe 520 arranged side by side and relatively thin. According to Paschen's law, plasma cannot pass through the second pipe 520 of smaller size, thereby effectively alleviating the risk of plasma entering the downstream second exhaust device 220 and extending the service life of the second exhaust device 220. At the same time, the plurality of second pipes 520 arranged side by side will not affect the suction capacity, ensuring the normal suction during the process.

[0095] For example, the diameter of the first pipe 510 may range from 50 mm to 200 mm, and of course, may also be other values, which are not specifically limited here. In addition, the diameter of the second pipe 520 may range from 1 mm to 5 mm, and of course, may also be other values, which are not specifically limited here.

[0096] refer to Figure 1In the embodiment of the present application, an upper electrode 610 and a lower electrode 620 may be provided in the reaction chamber 110, wherein the upper electrode 610 is connected to the first RF power supply 310 so as to provide electrical energy to the upper electrode 610 through the first RF power supply 310; and the lower electrode 620 is connected to the second RF power supply 320 so as to provide electrical energy to the lower electrode 620 through the second RF power supply 320.

[0097] In addition, an electrode may be disposed in the secondary ignition chamber 120 , and the electrode is connected to the third RF power source 330 , so that the third RF power source 330 provides electrical energy to the electrode.

[0098] refer to Figure 2 In other embodiments, the electrode in the secondary ignition chamber 120 may also be connected to the first RF power supply 310. In this case, the electrode in the secondary ignition chamber 120 and the upper electrode 610 share a first RF power supply 310, which can facilitate control, reduce structural complexity, and reduce costs.

[0099] In addition, the first RF power source 310 is connected to the upper electrode 610 through the first RF matcher 410 , the second RF power source 320 is connected to the lower electrode 620 through the second RF matcher 420 , and the third RF power source 330 is connected to the electrode in the secondary ignition chamber 120 through the third RF matcher 430 .

[0100] Of course, when the electrode of the secondary ignition chamber 120 and the upper electrode 610 share the first RF power supply 310, the electrode of the secondary ignition chamber 120 and the upper electrode 610 are respectively connected to the first RF matcher 410 through adjustable capacitors, and the first RF matcher 410 is connected to the first RF power supply 310; at the same time, the RF power allocated to each is adjusted by the respective adjustable capacitors, specifically, the larger the adjustable capacitor, the greater the allocated RF power.

[0101] The semiconductor process equipment in the embodiment of the present application may further include at least one memory and at least one processor, wherein the memory is used to store a computer program, and the processor is used to execute the above-mentioned metal layer etching method according to the computer program.

[0102] In summary, the embodiment of the present application etches the metal layer through the first etching step, etches the remaining metal and the nitride layer through the second etching step, and uses the CN chemical group formed by the reaction of the carbon element in the second etching gas with the nitrogen element in the nitride layer to indicate the etching end point of the metal layer and the nitride layer, thereby effectively alleviating the occurrence of over-etching caused by the fast etching speed, and can also improve the detection sensitivity of the etching end point to solve the problem that the etching end point is difficult to grasp.

[0103] In addition, by arranging the secondary ignition chamber 120 between the first pumping device 210 and the second pumping device 220, the sensitivity of indicating the etching end point can be improved through the higher chamber pressure in the secondary ignition chamber 120, so as to adapt to the etching process with a smaller aperture ratio and also facilitate ignition.

[0104] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A metal layer etching method, characterized in that: The metal layer etching method comprises: Performing a first etching step, introducing a first etching gas into the reaction chamber (110) to etch the metal layer, wherein a nitride layer is disposed below the metal layer, and the nitride layer is in contact with the metal layer; The spectral intensity of the CN spectral signal is detected. When the spectral intensity increases faster, a second etching step is performed, and a second etching gas is introduced into the reaction chamber (110) to etch the remaining metal layer and the nitride layer. The second etching gas contains a C element, and the C element is used to form a CN chemical group with an N element in the nitride layer.

2. The metal layer etching method according to claim 1, characterized in that: The second etching step includes a first etching stage and a second etching stage, wherein the first etching stage is used to etch the remaining metal layer and the nitride layer, and the second etching stage is used to etch the remaining nitride layer.

3. The metal layer etching method according to claim 2, characterized in that: The process recipes used in the first etching stage and the second etching stage are the same.

4. The metal layer etching method according to claim 1, characterized in that: The upper electrode power of the first etching step is greater than the upper electrode power of the second etching step, and the lower electrode power of the first etching step is greater than the lower electrode power of the second etching step; and / or The pressure of the reaction chamber (110) in the first etching step is greater than the pressure of the reaction chamber (110) in the second etching step.

5. The metal layer etching method according to claim 1, characterized in that: The CN spectrum signal of the first etching step tends to be stable at a first spectrum intensity value; When the first etching step is finished, the increase rate of the spectral intensity is accelerated.

6. The metal layer etching method according to claim 2, characterized in that: The spectral intensity of the CN spectral signal at the end point of the first etching stage tends to be stable; The spectral intensity of the CN spectral signal at the end point of the second etching stage drops rapidly; or the second etching stage begins to drop and is delayed for a predetermined time as the end point.

7. The metal layer etching method according to claim 6, characterized in that: The CN spectrum signal in the first etching stage tends to be stable at a second spectrum intensity value, and the CN spectrum signal in the second etching stage tends to be stable at a third spectrum intensity value, and the third spectrum intensity value is smaller than the second spectrum intensity value.

8. The metal layer etching method according to claim 1, characterized in that: The nitride layer includes TiN.

9. The metal layer etching method according to claim 1, characterized in that: The second etching gas is a fluorine-free gas; and / or The second etching gas includes a carbon-containing gas and a chlorine-containing gas, and the carbon-containing gas includes at least one of methane, carbon tetrachloride or aliphatic halogenated hydrocarbons.

10. The metal layer etching method according to claim 1, characterized in that: The metal layer includes aluminum; the first etching gas includes chlorine-containing gas; or The metal layer includes tungsten; and the first etching gas includes a fluorine-containing gas.

11. A semiconductor process equipment for etching a metal layer, characterized in that: The semiconductor process equipment comprises a reaction chamber (110) and a secondary ignition chamber (120); an outlet end of the reaction chamber (110) is connected in sequence to a first gas pumping device (210) and a second gas pumping device (220); and the secondary ignition chamber (120) is arranged between the first gas pumping device (210) and the second gas pumping device (220); The semiconductor process equipment further comprises a spectrum signal detection device (710), which is opposite to the window of the secondary ignition chamber (120) and is used for detecting the spectrum signal in the secondary ignition chamber (120) through the window.

12. The semiconductor process equipment according to claim 11, characterized in that: The secondary ignition chamber (120) adopts a capacitively coupled plasma processing device, comprising an ignition chamber (121) and a parallel plate capacitor (122); The parallel plate capacitor (122) is arranged in the starting cavity (121), and the parallel plate capacitor (122) is used to be connected to a radio frequency power source.

13. The semiconductor process equipment according to claim 11, characterized in that: The first air extraction device (210) is connected to the inlet of the secondary ignition chamber (120) via a first pipe (510), and the outlet of the secondary ignition chamber (120) is connected to the second air extraction device (220) via a plurality of second pipes (520) arranged side by side, wherein the diameter of the second pipe (520) is smaller than the diameter of the first pipe (510).

14. The semiconductor process equipment according to claim 13, characterized in that: The diameter of the first pipe (510) ranges from 50 mm to 200 mm; The diameter of the second pipe (520) ranges from 1 mm to 5 mm.

15. The semiconductor process equipment according to any one of claims 11 to 14, characterized in that: An upper electrode (610) and a lower electrode (620) are provided in the reaction chamber (110), wherein the upper electrode (610) is connected to a first radio frequency power source (310), and the lower electrode (620) is connected to a second radio frequency power source (320); An electrode is provided in the secondary ignition chamber (120), and the electrode is connected to a third radio frequency power source (330).

16. The semiconductor process equipment according to any one of claims 11 to 14, characterized in that: An upper electrode (610) and a lower electrode (620) are provided in the reaction chamber (110), wherein the upper electrode (610) is connected to a first radio frequency power source (310), and the lower electrode (620) is connected to a second radio frequency power source (320); An electrode is provided in the secondary ignition chamber (120), and the electrode is connected to the first radio frequency power source (310).

17. The semiconductor process equipment according to any one of claims 11 to 16, characterized in that: The semiconductor process equipment further includes at least one memory and at least one processor; The memory is used to store computer programs; The processor is used to execute the metal layer etching method according to any one of claims 1 to 10 according to the computer program.

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