Etching method and etching apparatus

Abstract

To improve the efficiency of an etching process.SOLUTION: An etching method includes the steps of: making the inside of a process chamber that accommodates a substrate into a reduced pressure state; supplying water vapor into the process chamber after the step of making the reduced pressure state; etching a coated film formed on the substrate by supplying an etching gas containing hydrogen fluoride into the process chamber after the step of making the reduced pressure state; and detecting an O-H stretching vibration in the substrate by infrared spectroscopy in the step of supplying water vapor. The step of etching the coated film is performed when an O-H stretching vibration of equal to or greater than a predetermined threshold value is detected on the substrate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a substrate etching technology. Substrates to be processed include, for example, semiconductor wafers, glass substrates for liquid crystal displays, substrates for flat panel displays (FPDs) such as organic electroluminescence (EL) displays, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, glass substrates for photomasks, ceramic substrates, substrates for field emission displays (FEDs), and substrates for solar cells. [Background technology]

[0002] 2. Description of the Related Art Semiconductor device manufacturing processes include etching a coating film formed on a substrate, such as a silicon oxide film or a silicon nitride film.

[0003] Conventionally, wet etching based on hydrofluoric acid has been used to etch silicon oxide films, for example. However, as semiconductor devices become more highly integrated and the patterns they form become finer, wet etching has become problematic, as the surface tension of water can cause the patterns to collapse.

[0004] Therefore, a vapor phase etching technique using hydrofluoric acid vapor or anhydrous hydrogen fluoride gas has been adopted (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6782140 Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned vapor-phase etching technique, hydrogen fluoride gas dissolves in water to generate fluorine ions, which contribute to etching.

[0007] Therefore, it is desirable that sufficient moisture (such as water vapor) be present on the upper surface of the substrate during the etching process. However, if the process for supplying moisture to the upper surface of the substrate (for example, the process of supplying water vapor) takes a long time, the time required for the entire etching process will increase, and the processing efficiency will decrease. Therefore, it is desirable to increase the efficiency of the etching process while maintaining sufficient moisture on the upper surface of the substrate.

[0008] The technology disclosed in the present specification has been made in consideration of the problems described above, and is a technology for improving the efficiency of etching processing. [Means for solving the problem]

[0009] An etching method according to a first aspect of the technology disclosed in the present specification is an etching method for etching a silicon-containing coating film formed on a substrate, the method comprising the steps of: reducing the pressure inside a processing chamber that accommodates the substrate; supplying water vapor into the processing chamber after the reducing the pressure step; supplying an etching gas containing hydrogen fluoride into the processing chamber after the reducing the pressure step to etch the coating film formed on the substrate; and detecting OH stretching vibrations in the substrate by infrared spectroscopy during the water vapor supply step, wherein the step of etching the coating film is performed when the OH stretching vibrations detected in the substrate are equal to or greater than a predetermined threshold.

[0010] An etching method that is a second aspect of the technology disclosed in the present specification is related to the etching method that is the first aspect, and further includes a step of supplying water vapor into the processing chamber to clean the substrate after the step of etching the coating film.

[0011] An etching method that is a third aspect of the technology disclosed in the present specification is related to the etching method of the first or second aspect, and the step of detecting the OH stretching vibration is a step of detecting the height of a peak in a spectrum of a wavenumber corresponding to the OH stretching vibration.

[0012] An etching apparatus according to a fourth aspect of the technology disclosed in the present specification is an etching apparatus for etching a silicon-containing coating film formed on a substrate, and includes: a vacuum pump for reducing the pressure inside a processing chamber that accommodates the substrate; an etching gas supply unit that supplies an etching gas containing hydrogen fluoride into the processing chamber; a water vapor supply unit that supplies water vapor into the processing chamber; a detection unit that detects OH stretching vibrations in the substrate by infrared spectroscopy; and a control unit that controls at least the etching gas supply unit, the water vapor supply unit, and the detection unit, wherein the control unit controls the water vapor supply unit to supply the water vapor into the processing chamber in the reduced pressure state, controls the detection unit to detect the OH stretching vibrations in the processing chamber to which the water vapor has been supplied, and controls the etching gas supply unit to supply the etching gas into the reduced pressure processing chamber when the OH stretching vibrations are detected to be equal to or greater than a predetermined threshold.

[0013] An etching apparatus according to a fifth aspect of the technology disclosed in the present specification is related to the etching apparatus according to the fourth aspect, and the detection unit includes a light source arranged below the substrate and a light receiving unit arranged above the substrate and receiving light output from the light source, and further includes a plate unit arranged above the substrate and having a plurality of openings formed therein, and the light output from the light source is received by the light receiving unit through the openings in the plate unit. [Effects of the Invention]

[0014] According to at least the first and fourth aspects of the technology disclosed herein, the amount of water vapor on the top surface of the substrate before etching can be detected, thereby enabling etching to be performed at an appropriate timing, thereby minimizing the waiting time before etching and increasing the efficiency of the etching process.

[0015] Furthermore, objects, features, aspects, and advantages associated with the technology disclosed herein will become more apparent from the detailed description and accompanying drawings set forth below. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a side view schematically illustrating an example of the configuration of an etching apparatus according to an embodiment. [Figure 2] 4 is a flowchart illustrating an example of the operation of the etching apparatus according to the embodiment. [Figure 3] 1A and 1B are diagrams conceptually illustrating a process in which water vapor is supplied to a substrate. [Figure 4] FIG. 1 is a diagram conceptually illustrating an etching process. [Figure 5] 10 is a flowchart illustrating an example of a start operation of etching a substrate. [Figure 6] FIG. 1 is a diagram conceptually showing an infrared absorption spectrum showing OH stretching vibrations. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments will be described with reference to the accompanying drawings. In the following embodiments, detailed features will be shown for the purpose of explaining the technology, but these are merely examples and are not necessarily essential features for enabling the embodiments to be implemented.

[0018] The drawings are schematic, and for the sake of convenience, components may be omitted or simplified as appropriate. The relative sizes and positions of components shown in different drawings are not necessarily accurately depicted and may be changed as appropriate. Hatching may also be used in drawings such as plan views that are not cross-sectional views to facilitate understanding of the embodiments.

[0019] In the following description, the same components are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed descriptions of them may be omitted to avoid duplication.

[0020] Furthermore, in the description given in this specification, when a certain component is described as "comprising," "including," or "having," unless otherwise specified, this is not an exclusive expression that excludes the presence of other components.

[0021] Furthermore, although ordinal numbers such as "first" or "second" may be used in the descriptions in this specification, these terms are used for convenience to facilitate understanding of the contents of the embodiments, and the contents of the embodiments are not limited to the order that may result from these ordinal numbers.

[0022] Furthermore, in the description provided in this specification, terms that indicate specific positions or directions, such as "top," "bottom," "left," "right," "side," "bottom," "front," or "back," may be used, but these terms are used for convenience to facilitate understanding of the contents of the embodiments and have no relation to the positions or directions when the embodiments are actually implemented.

[0023] <Embodiment> The etching method and etching apparatus according to this embodiment will be described below.

[0024] <Configuration of the etching equipment> 1 is a side view schematically showing an example of the configuration of an etching apparatus 1 according to this embodiment. The etching apparatus 1 is a single-wafer etching apparatus that processes substrates W such as semiconductor wafers one by one.

[0025] In this embodiment, the silicon-containing coating film to be etched is a silicon oxide film, but the coating film is not limited to this and may be, for example, a silicon nitride film, etc. The silicon oxide film may also be a thermal silicon oxide film formed by thermal oxidation, or a silicon oxide film containing a large amount of impurities, such as a TEOS (Tetra Ethoxy Silane) film obtained by chemical vapor deposition (CVD), a BSG (Boron Silicate Glass) film, a PSG (Phospho Silicate Glass) film, or a BPSG (Boron-doped Phospho Silicate Glass) film obtained by CVD.

[0026] 1, the etching apparatus 1 includes a processing chamber 2, such as a chamber for processing a substrate W, and a control unit 3 that controls the operation of devices provided in the etching apparatus 1 or the opening and closing of valves. The control unit 3 includes a determination unit 31 that makes a predetermined determination based on input information, and a memory unit 32 that stores the input information, the results of the determination by the determination unit 31, information output from the determination unit 31, and the like.

[0027] The processing chamber 2 has, for example, a cylindrical shape and has an internal processing space for processing the substrate W. A substrate holder 4 that holds the substrate W in a substantially horizontal position is installed in the processing chamber 2. The substrate W is transported into the processing chamber 2 by a transport system (not shown) and then placed on the substrate holder 4.

[0028] Within the processing chamber 2 are provided a substrate holder 4 for holding the substrate W, a heating mechanism 5 built into the substrate holder 4 for heating the substrate W, a gas distribution plate 6 located above the substrate holder 4 within the processing chamber 2, an exhaust pipe 7 connected to and communicating with the processing chamber 2 for reducing the pressure inside the processing chamber 2, a pressure sensor 10 connected to the processing chamber 2, and a pipe 11 (mixed gas pipe) connected to and communicating with the upper part of the processing chamber 2.

[0029] The substrate holder 4 may hold the substrate W by means of a chuck pin or the like, or may hold the substrate W on its upper surface by suction.

[0030] The substrate W is heated to a predetermined temperature in the range of 30° C. to 200° C. by a heating mechanism 5 built into the substrate holder 4. As the heating mechanism 5, for example, a resistance heating type electric heater is assumed.

[0031] The gas dispersion plate 6 has a plurality of openings 61 formed therein, and is provided above the substrate W so as to separate the upper and lower sections of the processing chamber 2. The gas supplied from the pipes 11 is dispersed through the plurality of openings 61 in the gas dispersion plate 6 and further supplied below the gas dispersion plate 6. In this embodiment, the gas dispersion plate 6 has a plurality of openings 61 with an inner diameter of 0.1 mm formed therein at intervals of 5 mm. However, the inner diameter and intervals of the openings are not limited to these. The gas dispersion plate 6 may also be provided in multiple stages.

[0032] The pressure sensor 10 is a sensor that measures the pressure (degree of vacuum) inside the processing chamber 2, and can output the pressure measurement results to the control unit 3 via wired or wireless communication means.

[0033] The exhaust pipe 7 is provided with a control valve 21, an APC (Auto Pressure Controller) valve 9 located downstream of the control valve 21, and a decompression pump 8 located downstream of the APC valve 9 and configured to reduce the pressure inside the processing chamber 2 via the exhaust pipe 7. The APC valve 9 adjusts the pressure inside the processing chamber 2 by adjusting the exhaust flow rate from the processing chamber 2. A determination unit 31 in the control unit 3 can adjust the aperture of the APC valve 9 so that the pressure inside the processing chamber 2 measured by the pressure sensor 10 becomes the desired pressure. Adjusting the pressure in two stages using the control valve 21 and the APC valve 9 allows for accurate pressure adjustment over a wide pressure range. Depending on the specifications of the apparatus, either the control valve 21 or the APC valve 9 may be omitted.

[0034] In this embodiment, the decompression pump 8 is described as the means for decompressing the interior of the processing chamber 2, but the decompression means is not limited to this, and for example, the decompression may be achieved by factory utility exhaust.

[0035] Pipe 11 is connected to pipes 12, 13, and 14 on the upstream side, and is a pipe where gases supplied from each pipe join together. The gases joined in pipe 11 are supplied to the upper part of processing chamber 2.

[0036] The pipe 12 is provided with a control valve 22 and a nitrogen supply source 42 located upstream of the control valve 22. The control valve 22 controls the flow rate of nitrogen (inert gas) supplied from the nitrogen supply source 42 to the pipe 12.

[0037] Pipe 13 is provided with a control valve 23 and a hydrogen fluoride gas supply source 43 located upstream of control valve 23. Control valve 23 controls the flow rate of hydrogen fluoride gas supplied from hydrogen fluoride gas supply source 43 to pipe 13. Note that hydrogen fluoride gas supply source 43 may be, for example, a high-pressure cylinder of anhydrous hydrogen fluoride.

[0038] Pipe 14 is provided with control valve 24, vaporizer 25 located upstream of control valve 24, and water vapor supply source 44 located upstream of vaporizer 25. Furthermore, upstream of pipe 14A branching off from pipe 14 at vaporizer 25, nitrogen supply source 45 is provided.

[0039] In vaporizer 25, deionized water (DIW) supplied from water vapor supply source 44 is vaporized and pressure-fed by nitrogen (inert gas) supplied from nitrogen supply source 45. Then, control valve 24 controls the flow rate of the vaporized water vapor supplied from pipe 14 to pipe 11.

[0040] The etching apparatus 1 also includes a Fourier-transform infrared spectrophotometer (FTIR) 50 as an analyzer that uses infrared spectroscopy to analyze the inside of the processing chamber 2. In this embodiment, the FTIR 50 is used as the infrared spectrophotometer corresponding to the analyzer, but a dispersive infrared spectrophotometer may also be used.

[0041] The FTIR 50 is disposed below the substrate W and includes a light source 51 that irradiates the substrate W with light from below, and a light receiving unit 52 that receives the light irradiated from the light source 51 above the substrate W.

[0042] Light emitted from the light source 51 enters the processing chamber 2 through a light-emitting window 53 provided below the substrate W and then passes through the substrate W. The light emitted from the light source 51 then passes through an opening 61 in the gas dispersion plate 6 to reach a light-receiving window 54 provided above the substrate W, and then enters the light-receiving unit 52 from the light-receiving window 54. Here, it is desirable that the opening 61 in the gas dispersion plate 6 is aligned on a straight line connecting the light source 51 and the light-receiving unit 52 so that the light emitted from the light source 51 reaches the light-receiving unit 52 without interfering with the gas dispersion plate 6. Note that in this embodiment, the light source 51, the light-receiving unit 52, and the opening 61 in the gas dispersion plate 6 are arranged at positions that overlap each other in a plan view, but the arrangement of these three elements is not limited to this.

[0043] The light-projecting window 53 and the light-receiving window 54 are made of a material (for example, quartz) that is transparent to infrared light and has high vacuum resistance.

[0044] The determination unit 31 of the control unit 3 calculates a transmission spectrum by Fourier transforming the interferogram of light received by the light receiving unit 52 of the FTIR 50. The determination unit 31 then calculates a transmission spectrum for each of a state to be measured (for example, a state before water vapor is supplied to the substrate W held by the substrate holder 4) and a reference state (for example, a state after water vapor is supplied to the substrate W held by the substrate holder 4), and determines the presence or absence of a sample to be detected based on the difference between the two.

[0045] In addition to the above, the judgment unit 31 of the control unit 3 performs temperature adjustment of the heating mechanism 5 in the etching apparatus 1, flow rate adjustment of the control valve 22, flow rate adjustment of the control valve 23, flow rate adjustment of the control valve 24, flow rate adjustment of the control valve 21, exhaust operation of the pressure reducing pump 8, measurement operation of the pressure sensor 10, and adjustment of the opening degree of the APC valve 9.

[0046] The control unit 3 controls each control valve to select the gas to be supplied from the pipe 11 into the processing chamber 2 from nitrogen, hydrogen fluoride gas, and water vapor. The selected gas then passes through the gas distribution plate 6 in the processing chamber 2 and reaches the substrate W.

[0047] The supply rate of hydrogen fluoride gas supplied to etch a coating film such as a silicon oxide film formed on the substrate W is, for example, 100 cc / min to 2000 cc / min. The supply rate of water vapor mixed with this hydrogen fluoride gas is, for example, 300 cc / min to 10000 cc / min.

[0048] In the process of cleaning the substrate surface after etching the silicon oxide film (described later), the supply rate of water vapor is, for example, 300 cc / min to 10,000 cc / min.

[0049] During processing of the substrate W, the pressure inside the processing chamber 2 is maintained, for example, at not less than 1 Pa and not more than 30,000 Pa. The pressure inside the processing chamber 2 is controlled by the control unit 3 adjusting the aperture of the APC valve 9 in accordance with the supply amount of water vapor and the supply amount of the mixed gas of water vapor and hydrogen fluoride gas so that the pressure inside the processing chamber 2 indicated by the pressure sensor 10 becomes a predetermined pressure.

[0050] <Operation of the etching equipment> The operation of the etching apparatus according to this embodiment will be described below. Fig. 2 is a flowchart showing an example of the operation of the etching apparatus according to this embodiment. The following operation is executed under the control of the control unit 3.

[0051] First, the substrate W is transported into the processing chamber 2 by a transport system (not shown), and then placed on the substrate holder 4 (step ST1). After the substrate W is placed on the substrate holder 4, the substrate W is heated to a predetermined temperature in the range of 30°C to 200°C by the heating mechanism 5 built into the substrate holder 4.

[0052] Next, after the substrate W is placed on the substrate holder 4, the vacuum pump 8 starts to evacuate the processing chamber 2 (step ST2). The vacuum pumping is continued until the pressure in the processing chamber 2 reaches about 0.1 Pa, and the atmospheric air in the processing chamber 2 is exhausted.

[0053] The evacuation time is determined by the capacity of the vacuum pump used for evacuation and the allowable evacuation time, but reducing the pressure as much as possible will allow the atmospheric atmosphere inside the processing chamber 2 to be exhausted and the processing chamber 2 to be clean.

[0054] Next, after the pressure inside the processing chamber 2 reaches approximately 0.1 Pa, water vapor is supplied into the processing chamber 2 through the pipes 14 and 11 (step ST3). The supply flow rate of the water vapor is adjusted to a predetermined flow rate by the control valve 24, and the water vapor is supplied from the pipe 11 into the processing chamber 2.

[0055] The pressure inside the processing chamber 2 is monitored by a pressure sensor 10 so that the pressure inside the processing chamber 2 reaches a predetermined vacuum level, and the control unit 3 adjusts the opening of the APC valve 9 based on the pressure indicated by the pressure sensor 10. The supply time for water vapor in step ST3 is not particularly limited, but may be long enough to form a thin layer of water over the entire surface of the substrate W (for example, about 1 second or more and 10 seconds or less).

[0056] The water vapor passes through the plurality of openings 61 in the gas distribution plate 6 and is supplied to the entire surface of the substrate W. The water vapor that has reached the entire surface of the substrate W forms a thin layer of water on the upper surface of the substrate W.

[0057] 3 is a conceptual diagram illustrating a process of supplying water vapor to a substrate. As shown in the example of FIG. 3, water vapor 44A is supplied to the upper surface of the substrate W, whereby a water film 72 is formed on the upper surface of a silicon oxide film 70.

[0058] After the water vapor has been supplied for a predetermined time, the hydrogen fluoride gas is adjusted to a predetermined supply flow rate by control valve 23, and further, the vaporized water vapor is adjusted to a predetermined supply flow rate by control valve 24, and the hydrogen fluoride gas and water vapor are mixed in pipe 11 to form a mixed gas. Then, the mixed gas is supplied from pipe 11 into processing chamber 2.

[0059] Next, the mixed gas supplied into the processing chamber 2 passes through the plurality of openings in the gas distribution plate 6 and is uniformly supplied to the entire surface of the substrate W, and further etches the silicon oxide film formed on the upper surface of the substrate W (step ST4). That is, the mixed gas functions as an etching gas.

[0060] 4 is a diagram conceptually illustrating the above-described etching process. As shown in the example of FIG. 4, a silicon oxide film 70 formed on the upper surface of a substrate W is etched by a mixed gas of hydrogen fluoride gas 43A and water vapor 44A.

[0061] The supply flow rates of water vapor 44A and hydrogen fluoride gas 43A are determined in advance depending on the type of coating film to be etched. For example, in the case of etching silicon oxide film 70 as in this embodiment, the supply flow rate of water vapor 44A is set in the range of 300 cc / min to 10,000 cc / min, and the supply flow rate of hydrogen fluoride gas 43A is set in the range of 100 cc / min to 2,000 cc / min.

[0062] In this embodiment, water vapor 44A is supplied before the mixed gas (etching gas) is supplied. Therefore, a water film 72 is formed on the upper surface of the substrate W before hydrogen fluoride gas 43A, which is an etching species for silicon oxide film 70, reaches the upper surface of the substrate W. Therefore, hydrogen fluoride gas 43A dissolves in water film 72, generating fluorine ions, allowing etching to begin immediately.

[0063] When etching of the silicon oxide film 70 by the etching gas is completed, the control valve 23 is closed to stop the supply of the etching gas. After the etching process, water vapor 44A is supplied by adjusting the control valve 24 and is supplied into the processing chamber 2 through the pipe 14 (step ST5).

[0064] The water vapor 44A supplied after the etching process passes through the plurality of openings 61 in the gas dispersion plate 6 and reaches the entire surface of the substrate W. By supplying the water vapor 44A to the substrate W after etching of the silicon oxide film 70 and cleaning (rinsing) it, fluorine (SiF-based residues) remaining on the surface of the substrate W is removed.

[0065] In this embodiment, water vapor is supplied into the processing chamber 2 after the etching process using the pipe 11 that supplies the etching gas into the processing chamber 2. However, the pipe that supplies the water vapor after the etching process may be a pipe separate from the pipe 11. In this case, it is possible to prevent hydrogen fluoride gas remaining inside the pipe 11 when the etching gas is supplied from being supplied into the processing chamber 2 when the water vapor is supplied after the etching process.

[0066] <Starting operation of substrate etching process> The following describes the starting operation of the etching process (corresponding to step ST4) of the substrate W in Fig. 2. Fig. 5 is a flowchart showing an example of the starting operation of the etching process of the substrate W.

[0067] First, after water vapor begins to be supplied into the processing chamber 2 in step ST3, the substrate W is irradiated with light (infrared light) from the light source 51 of the FTIR 50 (step ST11 in FIG. 5). The light irradiated from the light source 51 enters the processing chamber 2 through a light projection window 53 provided below the substrate W and then passes through the substrate W. The light then passes through the opening 61 of the gas dispersion plate 6 to reach a light receiving window 54 provided above the substrate W, and then enters the light receiving unit 52 from the light receiving window 54.

[0068] Since the light emitted from the light source 51 is absorbed based on the vibration or rotational motion of molecules present on and above the upper surface of the substrate W, the molecules present on and above the upper surface of the substrate W can be detected by comparing the infrared absorption spectrum (measurement spectrum) of the light incident on the light receiving unit 52 via the above-described path with the infrared absorption spectrum of reference light (reference spectrum). Note that the reference spectrum corresponds to, for example, the spectrum of light incident when the substrate W is held in the processing chamber 2 before water vapor is supplied thereto.

[0069] Fig. 6 is a diagram conceptually showing an infrared absorption spectrum showing OH stretching vibration. In Fig. 6, the vertical axis represents intensity, and the horizontal axis represents wave number (cm -1 As shown in Figure 6, the infrared absorption spectrum showing the OH stretching vibration is at a wave number of 3600 cm -1 Above 2500cm -1 It has peaks at the following positions:

[0070] 6, when the infrared absorption spectrum (difference spectrum) detected in the FTIR 50 as the difference between the measurement spectrum and the reference spectrum has a peak corresponding to the wavenumber position of the infrared absorption spectrum showing the OH stretching vibration shown in FIG. 6, water vapor present on and above the upper surface of the substrate W can be detected. Furthermore, based on the height (intensity) of the peak corresponding to the OH stretching vibration, the amount of water vapor present on and above the upper surface of the substrate W can be measured. From the amount of water vapor, it can also be inferred whether or not a water film has been formed on the upper surface of the substrate W.

[0071] Therefore, the determination unit 31 of the control unit 3 calculates a measurement spectrum by Fourier transforming the interferogram input from the light receiving unit 52, and further calculates a difference spectrum based on the measurement spectrum and a reference spectrum pre-stored in the memory unit 32 (step ST12 in FIG. 5).The determination unit 31 then compares the difference spectrum with an infrared absorption spectrum showing OH stretching vibrations pre-stored in the memory unit 32, thereby determining whether the difference spectrum shows an amount of water vapor equal to or greater than a predetermined threshold (step ST13 in FIG. 5).

[0072] If the difference spectrum does not indicate an amount of water vapor greater than or equal to the threshold value (i.e., if the difference spectrum does not have a peak of sufficient height at the wavenumber position of the infrared absorption spectrum shown in Figure 6), the judgment unit 31 returns to step ST11 while continuing the process of supplying water vapor into the processing chamber 2.

[0073] On the other hand, if the difference spectrum indicates an amount of water vapor equal to or greater than the threshold value (i.e., if the difference spectrum has a peak of sufficient height at the wavenumber position of the infrared absorption spectrum shown in Figure 6), the judgment unit 31 opens the control valve 23 to start the etching process of the substrate W (step ST14 in Figure 5).

[0074] Here, the threshold value used in determining whether the difference spectrum indicates water vapor in step ST13 can be a value determined in advance through experiments, etc. For example, a measured spectrum is calculated using a substrate W having a thin water layer (water film 72) formed on its upper surface, and a difference spectrum with a common reference spectrum is calculated in advance, and the height of the peak in the difference spectrum can be used as the threshold value.

[0075] The detection of the peak value of the difference spectrum can be started before etching processing is performed on the substrate W and can be continued after starting the etching processing on the substrate W. In this way, it is possible to proceed with the etching processing by efficiently dissolving the etching gas into the water layer (water film 72) while checking whether a thin water layer (water film 72) is formed on the upper surface of the substrate W during the etching processing.

[0076] In this case, the wave number of the Si-F stretching vibration mainly detected from the hydrogen fluoride used in the etching process of the substrate W is, for example, 945 cm -1 This wavenumber is significantly different from the wavenumber of the OH stretching vibration that is primarily detected from water vapor, and therefore does not significantly affect the detection accuracy of the OH stretching vibration.

[0077] On the other hand, the detection of the peak value of the difference spectrum may be limited to only before the substrate W is subjected to the etching process.

[0078] <Effects of the above-described embodiments> Next, examples of effects obtained by the above-described embodiments will be described. Note that in the following description, the effects will be described based on the specific configurations exemplified in the above-described embodiments, but these may be replaced with other specific configurations exemplified in the present specification as long as the same effects are obtained. In other words, for convenience, only one of the corresponding specific configurations may be described as a representative below, but the representatively described specific configuration may be replaced with another corresponding specific configuration.

[0079] According to the embodiment described above, in the etching method, the processing chamber 2 accommodating the substrate W is depressurized. After the depressurization step, water vapor 44A is supplied into the processing chamber 2. After the depressurization step, an etching gas containing hydrogen fluoride is supplied into the processing chamber 2, and the hydrogen fluoride gas is dissolved in the water film 72 formed on the upper surface of the substrate W, thereby etching the coating film formed on the substrate W. Here, the coating film corresponds to, for example, the silicon oxide film 70. Meanwhile, in the step of supplying the water vapor 44A, OH stretching vibrations in the substrate W are detected by infrared spectroscopy. Furthermore, the step of etching the silicon oxide film 70 is performed when OH stretching vibrations equal to or greater than a predetermined threshold are detected in the substrate W.

[0080] According to this configuration, by detecting the amount of water vapor (moisture content) on the upper surface of the substrate W before the etching process, the etching process can be performed at the timing when the upper surface of the substrate W is in a state suitable for the etching process (for example, a state in which a water film 72 has been formed on the upper surface of the substrate W). Therefore, the waiting time before the etching process can be minimized and the efficiency of the etching process can be improved.

[0081] Furthermore, according to the embodiment described above, in the etching method, after the step of etching the silicon oxide film 70, water vapor 44A is supplied into the processing chamber 2 to clean the substrate W. With this configuration, SiF-based residues remaining on the upper surface of the substrate W after the etching process can be washed away.

[0082] Furthermore, according to the embodiment described above, the step of detecting OH stretching vibrations is a step of detecting the height of a peak in the wavenumber spectrum corresponding to the OH stretching vibrations. With this configuration, the amount of water vapor on the top surface of the substrate W can be detected with high accuracy based on the height of the peak in the wavenumber spectrum, and the timing to start the etching process for the substrate W can be appropriately determined.

[0083] According to the embodiment described above, the etching apparatus includes a pressure-reducing pump 8, an etching gas supply unit, a water vapor supply unit, a detection unit, and a control unit 3. The etching gas supply unit corresponds to, for example, a gas supply mechanism that mixes gases supplied from a hydrogen fluoride gas supply source 43 and a water vapor supply source 44 and supplies the resulting mixture into the processing chamber 2. The water vapor supply unit corresponds to, for example, a water vapor supply mechanism that supplies water vapor supplied from the water vapor supply source 44 into the processing chamber 2. The detection unit corresponds to, for example, an FTIR spectrometer 50. The pressure-reducing pump 8 reduces the pressure inside the processing chamber 2 that accommodates the substrate W. The etching gas supply unit supplies an etching gas containing hydrogen fluoride into the processing chamber 2. The water vapor supply unit supplies water vapor into the processing chamber 2. The FTIR spectrometer 50 detects OH stretching vibrations in the substrate W using infrared spectroscopy. The control unit 3 controls the operations of at least the etching gas supply unit, the water vapor supply unit, and the FTIR spectrometer 50. Specifically, the control unit 3 controls the water vapor supply unit so that water vapor 44A is supplied into the reduced-pressure state processing chamber 2. The control unit 3 also controls the FTIR 50 so that OH stretching vibration is detected in the processing chamber 2 to which water vapor 44A has been supplied. The control unit 3 also controls the etching gas supply unit so that etching gas is supplied into the reduced-pressure state processing chamber 2 when OH stretching vibration equal to or greater than a predetermined threshold is detected.

[0084] According to this configuration, by detecting the amount of water vapor (moisture content) on the upper surface of the substrate W before the etching process, the etching process can be performed at the timing when the upper surface of the substrate W is in a state suitable for the etching process (for example, a state in which a water film 72 has been formed on the upper surface of the substrate W). Therefore, the waiting time before the etching process can be minimized and the efficiency of the etching process can be improved.

[0085] Furthermore, according to the embodiment described above, the FTIR 50 includes a light source 51 and a light receiving unit 52. The etching apparatus also includes a plate unit. Here, the plate unit corresponds to, for example, the gas dispersion plate 6. The light source 51 is disposed below the substrate W. The light receiving unit 52 is disposed above the substrate W and receives light output from the light source 51. The gas dispersion plate 6 is disposed above the substrate W and has a plurality of openings 61 formed therein. The light output from the light source 51 passes through the openings 61 in the gas dispersion plate 6 and is received by the light receiving unit 52. With this configuration, the light emitted from the light source 51 reaches the light receiving unit 52 without interfering with the gas dispersion plate 6, thereby maintaining high detection accuracy of the light spectrum in the FTIR 50.

[0086] <Modifications of the above-described embodiments> In the embodiments described above, the material, composition, dimensions, shape, relative positional relationship, or implementation conditions of each component may also be described, but these are merely examples in all aspects and are not limiting.

[0087] Thus, numerous variations and equivalents not shown are contemplated within the scope of the technology disclosed herein, including, for example, the modification, addition, or omission of at least one component.

[0088] Furthermore, in the embodiments described above, when a material name is mentioned without any particular specification, it is assumed that the material may contain other additives, such as an alloy, unless a contradiction arises. [Explanation of symbols]

[0089] 1. Etching equipment 2. Processing chamber 3. Control Unit 8. Vacuum pump 44A Water vapor 51 Light source 52 Light receiving part 61 Aperture W substrate

Claims

1. An etching method for etching a silicon-containing coating film formed on a substrate, comprising: creating a reduced pressure inside a processing chamber that accommodates the substrate; supplying water vapor into the processing chamber after the step of reducing the pressure; a step of supplying an etching gas containing hydrogen fluoride into the processing chamber after the step of reducing the pressure, thereby etching the coating film formed on the substrate; detecting O-H stretching vibrations in the substrate by infrared spectroscopy in the step of supplying water vapor; the step of etching the coating film is performed when the O-H stretching vibration is detected on the substrate at a level equal to or greater than a predetermined threshold value; Etching method.

2. 2. The etching method according to claim 1, further comprising the step of supplying water vapor into the processing chamber to clean the substrate after the step of etching the coating film. Etching method.

3. 3. The etching method according to claim 1 or 2, the step of detecting the O-H stretching vibration is a step of detecting the height of a peak in a spectrum of a wave number corresponding to the O-H stretching vibration. Etching method.

4. An etching apparatus for etching a silicon-containing coating film formed on a substrate, a vacuum pump for reducing the pressure inside a processing chamber that accommodates the substrate; an etching gas supply unit that supplies an etching gas containing hydrogen fluoride into the processing chamber; a water vapor supply unit that supplies water vapor into the processing chamber; a detection unit that detects O-H stretching vibrations in the substrate by infrared spectroscopy; a control unit that controls operations of at least the etching gas supply unit, the water vapor supply unit, and the detection unit, The control unit controlling the water vapor supply unit so that the water vapor is supplied into the processing chamber in the reduced pressure state; controlling the detection unit so that the O-H stretching vibration is detected in the processing chamber to which the water vapor is supplied; controlling the etching gas supply unit so that the etching gas is supplied into the reduced-pressure state processing chamber when the O-H stretching vibration is detected to be equal to or greater than a predetermined threshold value; Etching equipment.

5. 5. The etching apparatus according to claim 4, The detection unit a light source disposed below the substrate; a light receiving unit disposed above the substrate and configured to receive light output from the light source; The substrate further includes a plate portion disposed above the substrate and having a plurality of openings formed therein; The light output from the light source passes through the opening in the plate portion and is received by the light receiving portion. Etching equipment.

Images