Etching methods and etching apparatus

Abstract

This invention provides an etching method and etching apparatus capable of suppressing pitting corrosion in molybdenum or tungsten and etching a titanium nitride film on a substrate containing titanium nitride and molybdenum or tungsten. The etching method includes the following steps: preparing a substrate containing titanium nitride and molybdenum or tungsten; and supplying a process gas containing ClF3 gas and N2 gas to the substrate to etch the titanium nitride. During etching, the partial pressure ratio of the ClF3 gas to the N2 gas in the process gas is set to a value that nitrides the grain boundaries of Mo or W to a degree that suppresses pitting corrosion.

Description

Technical Field

[0001] This disclosure relates to an etching method and etching apparatus. Background Technology

[0002] In the metal film formation process, TiN films or Ti films are sometimes used as barrier metals. After the metal film is processed into the desired shape, there is a process to etch away the TiN film or Ti film, which has traditionally been done using wet etching. However, there are also structures where wet etching cannot remove only the TiN film, leading to research into etching the TiN film using dry processes. Patent Document 1, although using dry cleaning as an example, discloses a technique for removing TiN using ClF3 gas.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 4408124 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] This disclosure provides an etching method and etching apparatus capable of suppressing pitting corrosion in molybdenum or tungsten and etching a titanium nitride film on a substrate containing titanium nitride and molybdenum or tungsten.

[0008] Solution for solving the problem

[0009] One aspect of the etching method disclosed herein includes the following steps: preparing a substrate containing titanium nitride and molybdenum or tungsten; and supplying a processing gas containing ClF3 gas and N2 gas to the substrate to etch the titanium nitride, wherein, during the etching, the partial pressure ratio of the ClF3 gas to the N2 gas in the processing gas is such that it nitrides the grain boundaries of Mo or W to a degree that suppresses the formation of pitting corrosion.

[0010] The effects of the invention

[0011] According to this disclosure, an etching method and etching apparatus are provided that can suppress the formation of pitting corrosion in molybdenum or tungsten and etch a titanium nitride film on a substrate containing titanium nitride and molybdenum or tungsten. Attached Figure Description

[0012] Figure 1 This is a flowchart illustrating the etching method according to the first embodiment.

[0013] Figure 2 This is a cross-sectional view showing an example of a substrate to which the etching method according to the first embodiment can be applied.

[0014] Figure 3 It is shown Figure 2 A cross-sectional view of a specific example of the substrate structure.

[0015] Figure 4 This shows the etching. Figure 2 A cross-sectional view of the substrate after the TiN film has been applied.

[0016] Figure 5 This shows the etching. Figure 3 A cross-sectional view of the substrate after the TiN film has been applied.

[0017] Figure 6 It is shown in the Figure 2 A cross-sectional view showing the pitting corrosion that occurred on the surface of the Mo film when the exposed portion of the TiN film was etched away.

[0018] Figure 7 This diagram illustrates the first mechanism of pitting corrosion in the Mo film when the TiN film is etched.

[0019] Figure 8 This diagram illustrates the second mechanism of pitting corrosion in the Mo film when the TiN film is etched.

[0020] Figure 9 This is a flowchart illustrating the etching method according to the second embodiment.

[0021] Figure 10 This is a graph showing the etching amounts of TiN and Mo when etching was performed with a processing gas containing ClF3 and N2 gases after DHF pretreatment, and when etching was performed with the processing gas without DHF pretreatment.

[0022] Figure 11 This is a cross-sectional view showing an etching apparatus used to implement the etching method involved in the embodiments.

[0023] Figure 12 The image shows a SEM image of the Mo film surface after 120 seconds of etching under the conditions of Experiment Example 1A.

[0024] Figure 13 The image shows a SEM image of the Mo film surface after 120 seconds of etching under the conditions of Case B in Experiment 1.

[0025] Figure 14 The image shows a SEM image of the Mo film surface after 120 seconds of etching under the conditions of Experimental Example 1, Case C.

[0026] Figure 15 This is a SEM image of the Mo film surface after 120 seconds of etching under the conditions of Experimental Example 1, Case D.

[0027] Figure 16 This is a graph showing the changes in surface roughness RMS of samples 1-3 in Experimental Example 2 before and after gas treatment.

[0028] Figure 17 This is a graph showing the changes in etching amount of samples 1-3 in Experimental Example 2 before and after gas treatment. Detailed Implementation

[0029] The embodiments will now be described with reference to the accompanying drawings.

[0030] <Etching Method>

[0031] [First Implementation Method]

[0032] Figure 1 This is a flowchart illustrating the etching method according to the first embodiment.

[0033] In this embodiment, a substrate containing titanium nitride (TiN) and molybdenum (Mo) or tungsten (W) is first prepared (step ST1). Next, a processing gas containing chlorine trifluoride gas (ClF3 gas) and nitrogen gas (N2 gas) is supplied to the substrate to etch the TiN (step ST2).

[0034] The following is a detailed explanation.

[0035] In step ST1, the substrate has TiN and Mo or W, and has a structure in which the TiN and Mo or W are arranged in such a way that they are in contact with the process gas during the etching process. The substrate is not particularly limited as long as it has such a structure, but a semiconductor wafer is illustrated. The TiN, which is to be etched, is used as a barrier film for the Mo or W.

[0036] Figure 2 This is a cross-sectional view showing an example of a substrate to which the etching method of the first embodiment can be applied. Figure 2 The substrate S is configured as a semiconductor substrate such as silicon (in Figure 2 A structure 200 is formed on (not shown in the figure). The structure 200 has a SiO2 film 101 and a Mo film 102. An Al2O3 film 103 as an insulating barrier and a TiN film 104 as a barrier are sequentially formed on the surface of the SiO2 film 101. Moreover, the Mo film 102 is etched to the middle. As such a structure 200, Figure 3 As shown, an example is a 3D structure obtained by alternately stacking SiO2 film 101 and Mo film 102 on a semiconductor substrate 100, in which the Mo film 102 is grooved and etched via a groove (slit) 120. Furthermore, in Figure 2 and Figure 3In the structure 200, a native oxide film (MoO) is formed on the surface of the Mo film 102 and the TiN film 104. x TiON).

[0037] In step ST2, a processing gas containing N2 gas and ClF3 gas as an etching gas is supplied to the substrate having TiN and Mo or W to etch the TiN. For example, in Figure 2 , Figure 3 In the structure 200 after the Mo film 102 has been etched, the exposed TiN film 104 is etched to become... Figure 4 , Figure 5 The state.

[0038] In step ST2, the processing gas may contain other gases such as argon (Ar) in addition to ClF3 and N2. In this embodiment, the partial pressure ratio of ClF3 to N2 in the processing gas is set to a value that nitrides the grain boundaries of Mo or W to the extent that pitting corrosion is suppressed.

[0039] The following is an explanation of this point.

[0040] It has been clarified that when using processing gases containing ClF3 and N2 to etch TiN, pitting corrosion sometimes occurs in Mo or W when the goal is to completely remove TiN by destroying the oxide film present on the TiN surface, i.e., the hard TiON. For example, when etching TiN with a process gas containing ClF3 and N2, pitting corrosion sometimes occurs in Mo or W. Figure 2 When the exposed portion of the TiN film 104 is completely etched away, sometimes as Figure 6 As shown, pitting corrosion 105 occurs on the surface of the Mo film 102. The Mo film 102 is polycrystalline. Generally, the grain boundaries of polycrystalline materials have lower etch resistance and higher etch rate compared to the grains themselves. Therefore, it is speculated that pitting corrosion occurs according to the following two mechanisms.

[0041] The first mechanism is as follows Figure 7 As shown. Figure 7 As shown in (a), in the Mo film 102, there are grain boundaries 111 between multiple grains 110. As etching progresses, as shown in (b), the grain boundaries 111 are preferentially etched. With further etching progress, as shown in (c), the grains 110 are peeled off, resulting in pitting 105. The second mechanism is as follows: Figure 8 As shown. Figure 8 As shown in (a), when a slit 113 is formed along the grain boundary 111, as etching progresses, the etching proceeds along the slit 113, and as etching progresses further, it becomes pitting 105 as shown in (c). In fact, it is speculated that pitting is generated by a combination of these two mechanisms.

[0042] In this embodiment, to suppress the formation of pitting corrosion, the partial pressure ratio of ClF3 gas to N2 gas in the processing gas is reduced (i.e., less ClF3 gas and more N2 gas) to nitrid the grain boundaries of Mo or W. Specifically, the partial pressure ratio of ClF3 gas to N2 gas in the processing gas is set to a value that nitrides the grain boundaries of Mo or W to the extent that pitting corrosion is suppressed. By nitriding the grain boundaries, etching by ClF3 gas is suppressed, thereby suppressing the formation of pitting corrosion caused by the etching of grain boundaries.

[0043] Preferably, the partial pressure ratio (ClF3 / N2) of the processing gas, consisting of ClF3 gas and N2 gas, is set to 0.026 or less to achieve the pitting corrosion suppression effect obtained by improving the etch resistance of grain boundaries. Setting the ClF3 / N2 ratio to 0.026 or less increases the proportion of N2 gas relative to ClF3 gas, thereby promoting nitriding of Mo or W grain boundaries, effectively suppressing grain boundary etching, and thus inhibiting pitting corrosion.

[0044] In the TiN etching in step ST2, it is preferable to set the substrate temperature to the range of 20°C to 180°C and the pressure in the chamber to the range of 0.25 Torr to 2 Torr (33.3 Pa to 267 Pa).

[0045] Previously, wet etching was the mainstream method for etching TiN, but depending on the substrate structure, there are situations where wet etching alone is insufficient. For example, in substrates such as... Figure 2 , Figure 3 In the case of a substrate S with an Al2O3 film 103 and a TiN film 104 as shown, when attempting to remove the TiN film 104 by wet etching, the Al2O3 film will be etched down. Furthermore, it is known that TiN can be dry-etched using ClF3 gas, but as explained above, this process results in pitting corrosion in the coexisting Mo and W.

[0046] In this embodiment, the processing gas during etching is set to contain ClF3 gas and N2 gas, and the partial pressure of N2 gas is increased so that the partial pressure ratio of ClF3 gas to N2 gas is such that the intergranular boundaries of Mo or W are nitrided to a level that suppresses pitting corrosion. Thus, pitting corrosion of Mo or W can be suppressed, and TiN can be etched away without residue.

[0047] [Second Implementation]

[0048] Figure 9 This is a flowchart illustrating the etching method according to the second embodiment.

[0049] In this embodiment, firstly, similar to step ST1 of the first embodiment, a substrate containing TiN and Mo or W is prepared (step ST11). Next, the substrate is pretreated using dilute fluorine acid (DHF) (step ST12). Then, similar to step ST2 of the first embodiment, a processing gas containing ClF3 gas and N2 gas is supplied to the substrate to etch TiN (step ST13).

[0050] The following is a detailed explanation.

[0051] In step ST11, similarly to the first embodiment, the substrate has TiN and Mo or W, and has a structure in which these TiN and Mo or W are arranged in such a way that they are in contact with the process gas during the etching process. The substrate is not particularly limited as long as it has this structure, but a semiconductor wafer is exemplified. The TiN to be etched is used as a barrier film for the Mo or W. Specific examples of the substrate can also be given similarly to those in the first embodiment. Figure 2 and Figure 3 The structure of.

[0052] In step ST12, DHF is used to primarily remove the native oxide film (TiON) on the TiN surface. At this time, the Mo surface includes the native oxide film (MoO). x The portion of ) is also removed. By using DHF for pretreatment in this way, it is possible to suppress deviations in the incubation time of the etching process using the process gas in the next step ST13, thereby stabilizing the process.

[0053] Figure 10 This graph shows the etching amounts of TiN and Mo after DHF pretreatment using a processing gas containing ClF3 and N2 gases, and after etching using the processing gas without DHF pretreatment. As shown in the graph, it can be seen that the etching time for TiN is long when etching is performed using only the processing gas, but with DHF pretreatment, etching progresses without any incubation time. Furthermore, it was confirmed that Mo etching also progresses during DHF pretreatment, but smoothness is maintained and pitting corrosion does not occur as long as the etching time is short, within 60 seconds. Therefore, DHF pretreatment can eliminate process instability caused by incubation time deviations, thus stabilizing the process.

[0054] In step ST13, similarly to step ST2 of the first embodiment, a processing gas containing N2 gas and ClF3 gas is supplied to the substrate having TiN and Mo or W to etch TiN. The preferred conditions here are the same as in step ST2 of the first embodiment. That is, the partial pressure of N2 gas is increased so that the partial pressure ratio of ClF3 gas to N2 gas in the processing gas is a value that nitrides the grain boundaries of Mo or W to suppress pitting corrosion. Here, it is preferable to set the partial pressure ratio of ClF3 gas to N2 gas (ClF3 / N2) to 0.026 or less. In the etching of TiN in step ST13, similarly to step ST2 of the first embodiment, it is preferable to set the substrate temperature to a range of 20°C to 180°C and the pressure inside the chamber to a range of 0.25 Torr to 2 Torr (33.3 Pa to 267 Pa).

[0055] <An example of an etching apparatus>

[0056] Next, an example of an etching apparatus used to implement the etching method according to the embodiments will be described. Figure 11 This is a cross-sectional view showing an example of an etching apparatus.

[0057] like Figure 11 As shown, the etching apparatus 1 includes a sealed chamber 10. Inside the chamber 10 is a mounting stage 12 for horizontally placing a substrate S. The substrate S has TiN and either Mo or W, for example... Figure 2 , Figure 3 The etching apparatus 1 has a control unit 15, a gas supply mechanism 13 for supplying etching gas to the chamber 10, and an exhaust mechanism 14 for exhausting gas from the chamber 10.

[0058] The chamber 10 is composed of a chamber body 21 and a cover 22. The chamber body 21 has a generally cylindrical side wall portion 21a and a bottom portion 21b, and the chamber body 21 has an opening at the top, which is closed by the cover 22. The side wall portion 21a and the cover 22 are sealed by a sealing member (not shown), thereby ensuring the airtightness of the chamber 10.

[0059] The cover 22 has a cover member 25 forming the outer side and a spray head 26 embedded in the inner side of the cover member 25 and disposed facing the mounting platform 12. The spray head 26 has: a main body 27 having a cylindrical side wall 27a and an upper wall 27b; and a spray plate 28 disposed at the bottom of the main body 27. A space 29 is formed between the main body 27 and the spray plate 28.

[0060] A gas inlet passage 31 extending into the space 29 is formed in the upper wall 27b of the cover member 25 and the main body 27. The gas inlet passage 31 is connected to the piping 49 of the gas supply mechanism 13, which will be described later.

[0061] Multiple gas ejection holes 32 are formed in the spray plate 28, and gas that is introduced into the space 29 via the piping 49 and the gas introduction passage 31 is ejected from the gas ejection holes 32 into the space inside the chamber 10.

[0062] The side wall portion 21a is provided with a loading and unloading outlet 23 for loading and unloading the substrate S, which can be opened and closed by a gate valve 24.

[0063] The mounting stage 12, viewed from above, is approximately circular and is fixed to the bottom 21b of the chamber 10. A temperature control unit 35 is provided inside the mounting stage 12, which adjusts the temperature of the mounting stage 12 to control the temperature of the substrate S mounted on it. The temperature control unit 35 includes, for example, a heater for heating the mounting stage 12 and a pipeline for circulating a temperature-regulating medium (e.g., water). The temperature of the substrate S on the mounting stage 12 is controlled by adjusting the output of the heater and the flow rate of the temperature-regulating medium using a controller (not shown). A temperature sensor (not shown) is provided near the substrate S mounted on the mounting stage 12 to detect the temperature of the substrate S.

[0064] The gas supply mechanism 13 supplies a processing gas containing N2 gas and ClF3 gas as an etching gas. The gas supply mechanism 13 has a ClF3 gas supply source 45 for supplying ClF3 gas, an Ar gas supply source 46 for supplying Ar gas, and an N2 gas supply source 47 for supplying N2 gas. One end of each of these gas supply sources is connected to a ClF3 gas supply pipe 41, an Ar gas supply pipe 42, and an N2 gas supply pipe 43, respectively. The other ends of these three gas supply pipes are connected to a common pipe 49, which is connected to the aforementioned gas inlet passage 31. Flow control units 41a, 42a, and 43a are respectively provided in the ClF3 gas supply pipe 41, the Ar gas supply pipe 42, and the N2 gas supply pipe 43 for opening and closing the flow path and controlling the flow rate. The flow control units 41a, 42a, and 43a are, for example, flow controllers such as on / off valves and mass flow controllers.

[0065] Therefore, ClF3 gas, Ar gas as an inactive gas, and N2 gas are supplied from the gas supply sources 45, 46, and 47 through pipes 41, 42, 43, and 49 into the spray head 26, and are sprayed out from the gas outlet holes 32 of the spray plate 28 into the chamber 10.

[0066] The exhaust mechanism 14 has an exhaust pipe 52 connected to an exhaust port 51 formed at the bottom 21b of the chamber 10, and also has an automatic pressure control valve (APC) 53 disposed on the exhaust pipe 52 for controlling the pressure inside the chamber 10 and a vacuum pump 54 for exhausting the contents of the chamber 10.

[0067] Two capacitive pressure gauges, 56a and 56b, for high and low pressure respectively, are installed on the side wall of chamber 10 and inserted into chamber 10 to measure the pressure inside chamber 10. The opening of automatic pressure control valve (APC) 53 is adjusted based on the detection values ​​of capacitive pressure gauges 56a and 56b, thereby controlling the pressure inside chamber 10.

[0068] Typically, the control unit 15 is configured as a computer and includes a main control unit with a CPU that controls the various structural components of the etching apparatus 1. Additionally, the control unit 15 also includes input devices (keyboard, mouse, etc.), output devices (printer, etc.), display devices (monitor, etc.), and storage devices (storage media) connected to the main control unit. The main control unit of the control unit 15 controls the operation of the etching apparatus 1, for example, based on a processing procedure stored in or on a storage medium embedded in the storage device.

[0069] In this etching apparatus 1, a substrate S is placed into a chamber 10 and mounted on a stage 12. The stage 12 is heated by a temperature control unit 35, and the temperature of the substrate S is controlled by the stage 12 to a predetermined temperature within the range of, for example, 20°C to 180°C. Furthermore, with Ar gas and / or N2 gas supplied into the chamber 10, the pressure inside the chamber 10 is controlled to a predetermined pressure within the range of, for example, 0.25 Torr to 2 Torr (33.3 Pa to 267 Pa).

[0070] Then, at the point when the temperature of the substrate S and the pressure inside the chamber 10 have stabilized, ClF3 gas, used as an etching gas, is supplied into the chamber 10. At this time, the partial pressure ratio of ClF3 gas to N2 gas in the processing gas is set to a value that nitrides the grain boundaries of Mo or W to suppress pitting corrosion. Preferably, the partial pressure ratio of ClF3 gas to N2 gas (ClF3 / N2) is set to 0.026 or less.

[0071] By supplying the processing gas in this way, it is possible to etch TiN while suppressing the pitting corrosion of Mo or W.

[0072] After etching, the chamber 10 is purged with Ar gas and / or N2 gas, and then the substrate S is removed from the chamber 10.

[0073] <Experimental Example>

[0074] Next, the experimental examples will be explained.

[0075] [Experimental Example 1]

[0076] First, experiments were conducted to investigate the relationship between the partial pressure ratio of ClF3 gas to N2 gas (ClF3 / N2) and pitting corrosion.

[0077] Here, after actually performing DHF treatment on the substrate on which TiN and Mo films were formed, using Figure 11 The etching apparatus shown performs etching by changing the partial pressure ratio (ClF3 / N2) of ClF3 gas to N2 gas. Specifically, the substrate temperature is set to 80°C to 100°C, the pressure inside the chamber is set to 0.25 Torr to 2 Torr (33.3 Pa to 267 Pa), and the flow rates of ClF3 gas and N2 gas are varied as shown in cases A to D below. In case A, the ClF3 gas flow rate is set to 20 sccm, and the N2 gas flow rate is set to 390 sccm. The partial pressure ratio (ClF3 / N2) is 0.0512. In case B, the ClF3 gas flow rate is set to 20 sccm, and the N2 gas flow rate is set to 790 sccm. The partial pressure ratio (ClF3 / N2) is 0.0253. In case C, the ClF3 gas flow rate is set to 23 sccm, and the N2 gas flow rate is set to 1187 sccm. The partial pressure ratio (ClF3 / N2) is 0.0193. In case D, the ClF3 gas flow rate is set to 26 sccm, and the N2 gas flow rate is set to 1584 sccm. The partial pressure ratio (ClF3 / N2) is then 0.0164.

[0078] The etching was performed under conditions A to D, with etching times of 60 sec, 120 sec, 150 sec, 180 sec, and 240 sec. The results showed that in conditions A to C, TiN could be etched without residue when the etching time was 120 sec or more, and in condition D, TiN could be etched without residue when the etching time was 150 sec or more.

[0079] Furthermore, the states of the Mo film during etching under conditions A through D are as follows. In condition A, where the partial pressure ratio (ClF3 / N2) is 0.0512 (exceeding 0.026), and the etching time is 120 seconds, as follows... Figure 12The SEM images show pitting corrosion and a large surface roughness (RMS 2.45 nm). In contrast, in cases B to D where the partial pressure ratio (ClF3 / N2) is below 0.026, a good surface condition with no pitting corrosion visible on the Mo film was obtained under conditions where TiN could be etched without residue. Specifically, under condition B, with an etching time of 120 seconds, as shown... Figure 13 As shown in the SEM images, no pitting corrosion is observed on the Mo film, and the surface roughness RMS is 1.23 nm. Under condition C, when the etching time is 120 sec and 150 sec, no pitting corrosion is observed on the Mo film. At 150 sec, as shown in the images... Figure 14 As shown in the SEM images, the surface roughness RMS becomes as small as 1.07 nm. Under condition D, with an etching time of 150 sec, as... Figure 15 As shown in the SEM images, pitting corrosion is not visible on the Mo film, and the surface roughness RMS becomes an even smaller value as small as 1.05 nm.

[0080] [Experimental Example 2]

[0081] Next, experiments were conducted to confirm the mechanism of pitting corrosion inhibition of the Mo film.

[0082] Here, a substrate with a Mo film formed was prepared and subjected to DHF pretreatment. Furthermore, samples were prepared including one in the DHF pretreated state (Sample 1), one nitrided after DHF pretreatment (Sample 2), and one oxidized after DHF pretreatment (Sample 3). Nitriding was performed by heating at 300°C for 1 hour in an N2 atmosphere, and oxidation was performed by heating at 300°C for 1 hour in an O2 atmosphere. The surface roughness and etching amount of these samples were measured using AMF.

[0083] Next, the samples were gas-treated using gases containing ClF3 and N2. The substrate temperature was set to 80°C–100°C, the pressure within the chamber to 0.25 Torr–2 Torr (33.3 Pa–267 Pa), the ClF3 gas flow rate to 23 sccm, and the N2 gas flow rate to 1187 sccm. The surface roughness and etching depth of the gas-treated samples were measured using AMF.

[0084] exist Figure 16 and Figure 17 The changes in surface roughness RMS and etching amount before and after gas treatment are shown in Figures 1-3, respectively. Figure 16As shown, compared to sample 1 which did not undergo nitriding or oxidation treatment, the RMS before gas treatment decreased in sample 2 which underwent nitriding treatment, while the RMS before gas treatment increased in sample 3 which underwent oxidation treatment. Furthermore, after gas treatment, the RMS of samples 1 through 3 all increased, but there was a tendency for the increase to be smaller in sample 2 (nitrided) and larger in sample 3 (oxidized). Figure 17 As shown, the etching amount before gas treatment was the same in sample 1 (without nitriding and oxidation) and sample 2 (nitriding). In sample 3 (oxidation), the film thickened due to oxidation expansion. Furthermore, regarding the etching amount after gas treatment, the etching amount in sample 2 (nitriding) was less than that in sample 1, while the etching amount in sample 3 (oxidation) was greater than that in sample 1.

[0085] Furthermore, XPS analysis of the film surface composition of sample 2, which underwent nitriding treatment, revealed that the N concentration in sample 2 was approximately 6 at% before gas treatment and approximately 5 at% after gas treatment. In sample 3, which underwent oxidation treatment, the O concentration was approximately 70 at% before gas treatment and approximately 35 at% after gas treatment. This confirms that the Mo surface was nitrided and oxidized. As mentioned above, it can be confirmed that the Mo film becomes more difficult to etch through nitriding and more easily etched through oxidation.

[0086] This result confirms that the grain boundaries of the Mo film surface become difficult to etch through nitriding, thus making it less prone to pitting corrosion.

[0087] <Other Applications>

[0088] The embodiments have been described above, but it should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. The above embodiments may be omitted, substituted, or modified in various ways without departing from the scope of the appended claims and their spirit.

[0089] For example, Figure 2 , Figure 3 The substrate structure shown is merely an example; any substrate configured to allow Mo or W to contact the process gas during TiN etching can be used. Similarly, the etching apparatus described above is also just an example; various structures can be used. Furthermore, while a semiconductor wafer is shown as the substrate, it is not limited to semiconductor wafers; other substrates such as FPD (flat panel display) substrates (e.g., LCD substrates), ceramic substrates, etc., can also be used.

[0090] Explanation of reference numerals in the attached figures

[0091] 1: Etching apparatus; 12: Stage; 13: Gas supply mechanism; 14: Exhaust mechanism; 15: Control unit; 35: Temperature control unit; 100: Semiconductor substrate; 101: SiO2 film; 102: Mo film; 103: Al2O3 film; 104: TiN film; 105: Pitting etching; 120: Groove (gap); 200: Structure; S: Substrate.

Claims

1. An etching method, comprising the following steps: Prepare a substrate containing titanium nitride and molybdenum or tungsten; as well as A processing gas containing ClF3 and N2 is supplied to the substrate to etch the titanium nitride. In the etching process, the partial pressure ratio of ClF3 gas to N2 gas, i.e., ClF3 / N2, is set to 0.026 or less.

2. The etching method according to claim 1, wherein, Prior to the etching, the method further includes the following step: pretreating the substrate with dilute fluorine.

3. The etching method according to claim 1 or 2, wherein, The substrate has a structure in which a molybdenum film and a silicon film are stacked in between an aluminum oxide film and a titanium nitride film, and the molybdenum film is etched to expose the titanium nitride film.

4. The etching method according to claim 1 or 2, wherein, The etching temperature is 20℃~180℃.

5. The etching method according to claim 1 or 2, wherein, The etching pressure is 33.3 Pa to 267 Pa.

6. An etching apparatus comprising: A chamber for housing the substrate; A stage that holds the substrate within the cavity; A gas supply unit supplies a processing gas containing ClF3 gas and N2 gas into the chamber; An exhaust section that exhausts air from the chamber; Temperature control unit, which adjusts the temperature of the substrate on the mounting stage; and Control Department in, The control unit controls the gas supply unit, the exhaust unit, and the temperature control unit to perform the etching method according to any one of claims 1 to 5.

Images