Etching method and etching apparatus

Abstract

To suppress an increase in time required for substrate cleaning.SOLUTION: An etching method includes the steps of: etching a coated film formed on a substrate by supplying etching gas containing hydrogen fluoride into a process chamber after a step of making the pressure to be a state of reduced pressure; cleaning the substrate by supplying water vapor into the process chamber after the step of etching the coated film; and detecting Si-F stretching vibration in the substrate by infrared spectroscopy during the substrate cleaning step. The step of cleaning the substrate is terminated when the Si-F stretching vibration equal to or less than a predetermined first 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, fluorine remains on the surface of the silicon substrate after etching. If fluorine remains on the silicon surface after etching a silicon oxide film, the remaining fluorine reacts with the silicon, causing defects in the silicon and the formation of particles.

[0007] Therefore, a process of cleaning the etched substrate for a time that is expected to sufficiently remove fluorine is provided, but since it is difficult to determine the timing at which fluorine has been sufficiently removed, the cleaning process may take longer than necessary.

[0008] The technology disclosed in this specification has been made in consideration of the problems described above, and is a technology for preventing the time required to clean a substrate from becoming longer than necessary. [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 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; supplying water vapor into the processing chamber after the etching of the coating film to clean the substrate; and detecting Si-F stretching vibrations in the substrate by infrared spectroscopy during the substrate cleaning step, wherein the substrate cleaning step is terminated when the Si-F stretching vibrations detected in the substrate are equal to or less than a predetermined first threshold.

[0010] An etching method according to a second aspect of the technology disclosed in the present specification is related to the etching method according to the first aspect, and further includes the steps of: stopping the supply of water vapor when the Si-F stretching vibration is detected to be equal to or less than the threshold; and removing the substrate from the processing chamber after stopping the supply of water vapor.

[0011] An etching method according to a third aspect of the technology disclosed herein is related to the etching method according to the first or second aspect, in which the step of detecting Si-F stretching vibration is a step of detecting a peak height of a spectrum of wavenumbers corresponding to the Si-F stretching vibration.

[0012] An etching method according to a fourth aspect of the technology disclosed herein is related to any one of the first to third aspects of the etching method, in which the step of cleaning the substrate is terminated when, after the Si-F stretching vibration equal to or greater than a predetermined second threshold is detected in the substrate, the Si-F stretching vibration equal to or less than the first threshold is detected in the substrate.

[0013] a water vapor supply unit that supplies water vapor into the processing chamber; a detector that detects Si-F stretching vibrations in the substrate using infrared spectroscopy; and a controller that controls at least the operations of the etching gas supply unit, the water vapor supply unit, and the detector, wherein the controller controls the etching gas supply unit to supply the etching gas into the processing chamber in the reduced pressure state, controls the water vapor supply unit to supply the water vapor into the processing chamber after the etching gas has been supplied, controls the detector to detect the Si-F stretching vibrations in the processing chamber after the water vapor has been supplied, and controls the water vapor supply unit to stop the supply of water vapor when the Si-F stretching vibrations in the substrate are detected to be equal to or less than a predetermined threshold.

[0014] An etching apparatus according to a sixth aspect of the technology disclosed in the present specification is related to the etching apparatus according to the fifth 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]

[0015] According to at least the first and fifth aspects of the technology disclosed in the present specification, the cleaning process of the substrate can be terminated when the residue is removed, so that the time required for cleaning the substrate can be prevented from being longer than necessary while the SiF-based residue remaining on the substrate after etching of the coating film is appropriately removed.

[0016] 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]

[0017] [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] FIG. 1 is a diagram conceptually illustrating an etching process. [Figure 4] FIG. 10 is a diagram conceptually showing a step of supplying water vapor after etching processing is completed. [Figure 5] 10 is a flowchart illustrating an example of an operation for finishing a cleaning process for a substrate. [Figure 6] FIG. 1 is a diagram showing an infrared absorption spectrum showing Si—F stretching vibrations. DETAILED DESCRIPTION OF THE INVENTION

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] <Embodiment> The etching method and etching apparatus according to this embodiment will be described below.

[0025] <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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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 in which the substrate W is held after the etching process) and a reference state (for example, a state in which the substrate W is held before the etching process), and determines the presence or absence of a sample to be detected based on the difference between the two.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] <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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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).

[0057] 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.

[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] 3 is a diagram conceptually illustrating the above-described etching process. As shown in the example of FIG. 3, 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 is supplied before the mixed gas (etching gas) is supplied. Therefore, a layer of water (water film) is formed on the upper surface of the substrate W before the hydrogen fluoride gas 43A, which is an etching species for the silicon oxide film 70, reaches the upper surface of the substrate W. Therefore, etching can be started 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] 4 is a conceptual diagram illustrating a process of supplying water vapor after etching processing is completed. As shown in the example of FIG. 4, residue 71 remains on the upper surface of the substrate W after etching processing, and water vapor 44A is supplied to the substrate W.

[0065] The water vapor 44A supplied after the etching process passes through the plurality of openings 61 in the gas distribution 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 to clean (wash away), the fluorine (SiF-based residues 71) remaining on the surface of the substrate W is removed.

[0066] 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.

[0067] <About the completion of the substrate cleaning process> The following describes the operation for finishing the cleaning process (corresponding to step ST5) for the substrate W in Fig. 2. Fig. 5 is a flowchart showing an example of the operation for finishing the cleaning process for the substrate W.

[0068] First, while the substrate W held by the substrate holder 4 is being cleaned, 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 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.

[0069] 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, and therefore, 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 (reference spectrum) of reference light, it is possible to detect the molecules present on and above the upper surface of the substrate W. The reference spectrum corresponds to, for example, the spectrum of light incident on the substrate W while it is being held before etching processing is performed.

[0070] 6 is a diagram showing an infrared absorption spectrum showing Si-F stretching vibration. In FIG. 6, the vertical axis represents intensity and the horizontal axis represents wave number (cm -1As shown in FIG. 6, the infrared absorption spectrum showing the Si-F stretching vibration is at a wave number of 945 (cm -1 ) has a peak at the position.

[0071] 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 Si-F stretching vibration shown in Fig. 6, it is possible to detect SiF-based substances present on and above the upper surface of the substrate W. Furthermore, based on the height (intensity) of the peak corresponding to the Si-F stretching vibration, it is possible to measure the amount of SiF-based substances present on and above the upper surface of the substrate W.

[0072] 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 Si-F stretching vibrations pre-stored in the memory unit 32, thereby determining whether or not the difference spectrum indicates the presence of a SiF-based substance (step ST13 in FIG. 5). Note that if it is determined that "the difference spectrum indicates the presence of a SiF-based substance" even once during the cleaning process of successive substrates W, the determinations in step ST13 that are subsequently repeated shall always be that "the difference spectrum indicates the presence of a SiF-based substance."

[0073] If the difference spectrum does not indicate the presence of a SiF-based substance (i.e., if the difference spectrum does not have a peak corresponding to the wavenumber position of the infrared absorption spectrum shown in FIG. 6), the determination unit 31 closes the control valve 24 to terminate the cleaning process of the substrate W (step ST14 in FIG. 5). Then, the determination unit 31 carries out another processing step (such as a depressurization step) and then transfers the substrate W out of the processing chamber 2 (step ST15 in FIG. 5).

[0074] On the other hand, if the difference spectrum indicates the presence of a SiF-based substance (i.e., if it has a peak corresponding to the wavenumber position of the infrared absorption spectrum shown in FIG. 6), the judgment unit 31 judges whether the (current) amount of the SiF-based substance is equal to or less than a predetermined threshold value (first threshold value) (step ST16 in FIG. 5).

[0075] If the (current) amount of SiF-based substances is equal to or less than the threshold value (i.e., if the peak height is equal to or less than the threshold value), the determination unit 31 closes the control valve 24 to terminate the cleaning process of the substrate W (step ST14 in FIG. 5). Then, the determination unit 31 carries out the substrate W to outside the processing chamber 2 after another processing step (such as a depressurization step) (step ST15 in FIG. 5).

[0076] On the other hand, if the (current) amount of SiF-based substances is greater than the threshold value (i.e., if the height of the peak is greater than the threshold value), the determination unit 31 returns to step ST11 while continuing the cleaning process of the substrate W. That is, the Si-F stretching vibration is repeatedly detected.

[0077] Here, when determining whether or not the presence of a SiF-based substance is indicated in the above step ST13, a condition may be that the height of the peak corresponding to the infrared absorption spectrum indicating the Si-F stretching vibration is equal to or greater than a predetermined threshold value (second threshold value).

[0078] In the cleaning process of a substrate W, the amount of SiF-based residue remaining is expected to be greatest immediately after the etching process and to decrease as the cleaning process progresses. Therefore, by setting two thresholds in accordance with the change in the amount of remaining SiF-based residue, the accuracy of identifying the SiF-based residue can be improved. Here, the second threshold may be the same as or different from the first threshold. Furthermore, the ideal value of the first threshold is zero (not detected), but the first threshold may be determined in advance through experiments or the like to be a sufficiently low value that does not cause problems such as defects in silicon or particle formation.

[0079] In the above-described operation for terminating the cleaning process, light is irradiated from the light source 51 while the substrate W is being cleaned, and while the cleaning process of the substrate W is continued, it is determined whether or not the SiF-based residues on the upper surface of the substrate W have been sufficiently removed. In such a case, the timing for terminating the cleaning process of the substrate W can be determined without interrupting the cleaning process of the substrate W, thereby improving the efficiency of the substrate processing. In this case, the wave number of the OH stretching vibration mainly detected from the water vapor used in the cleaning process of the substrate W is, for example, 3600 cm -1 Above 2500cm -1 The wave number of the Si-F stretching vibration (945 cm) is mainly detected from the SiF residue. -1 ), it does not significantly affect the detection accuracy of the Si-F stretching vibration.

[0080] It is also possible to irradiate the substrate W with light from the light source 51 after temporarily halting the cleaning process thereon, and determine whether the SiF-based residues on the upper surface of the substrate W have been sufficiently removed.

[0081] <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.

[0082] According to the embodiment described above, in the etching method, the processing chamber 2 accommodating the substrate W is depressurized. After the depressurization step, an etching gas containing hydrogen fluoride is supplied into the processing chamber 2 to etch a coating film formed on the substrate W. Here, the coating film corresponds to, for example, the silicon oxide film 70. 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. Here, in the step of cleaning the substrate W, Si-F stretching vibrations in the substrate W are detected by infrared spectroscopy. The step of cleaning the substrate W is terminated when Si-F stretching vibrations equal to or less than a predetermined first threshold are detected in the substrate W.

[0083] According to this configuration, the cleaning process of the substrate W can be terminated at the timing when the residues are removed, so that the time required for cleaning the substrate W can be prevented from being longer than necessary while properly removing the SiF-based residues remaining on the upper surface of the substrate W after etching the silicon oxide film 70.

[0084] Furthermore, according to the embodiment described above, in the etching method, when Si-F stretching vibrations below a threshold value are detected, the supply of water vapor 44A is stopped. Furthermore, after the step of stopping the supply of water vapor 44A, the substrate W is removed from the processing chamber 2. With this configuration, the substrate W can be smoothly transported out of the processing chamber 2 after the step of cleaning the substrate W is completed.

[0085] Furthermore, according to the embodiment described above, the step of detecting the Si-F stretching vibration is a step of detecting the height of the peak in the wavenumber spectrum corresponding to the Si-F stretching vibration. With this configuration, the amount of SiF-based residue can be detected with high accuracy based on the height of the peak in the wavenumber spectrum, and the end timing of the cleaning step can be appropriately determined.

[0086] Furthermore, according to the embodiment described above, the process of cleaning the substrate W is terminated when Si-F stretching vibrations equal to or greater than a predetermined second threshold are detected in the substrate W, and then Si-F stretching vibrations equal to or less than the first threshold are detected in the substrate W. This configuration makes it possible to effectively remove SiF-based residues remaining on the top surface of the substrate W while reliably detecting Si-F stretching vibrations.

[0087] 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 Si-F 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 etching gas supply unit so that an etching gas is supplied into the reduced-pressure processing chamber 2. The control unit 3 also controls the water vapor supply unit so that water vapor is supplied into the processing chamber 2 after the etching gas has been supplied. The control unit 3 also controls the FTIR 50 so that Si-F stretching vibrations are detected in the processing chamber 2 after the water vapor has been supplied. The control unit 3 also controls the water vapor supply unit so that the supply of water vapor is stopped when Si-F stretching vibrations equal to or less than a predetermined threshold are detected in the substrate W.

[0088] According to this configuration, the cleaning process of the substrate W can be terminated at the timing when the residues are removed, so that the time required for cleaning the substrate W can be prevented from being longer than necessary while properly removing the SiF-based residues remaining on the upper surface of the substrate W after etching the silicon oxide film 70.

[0089] 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.

[0090] <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.

[0091] 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.

[0092] 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]

[0093] 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; after the step of reducing the pressure, supplying an etching gas containing hydrogen fluoride into the processing chamber to etch the coating film formed on the substrate; After the step of etching the coating film, supplying water vapor into the processing chamber to clean the substrate; and detecting Si—F stretching vibrations in the substrate by infrared spectroscopy in the step of cleaning the substrate. the step of cleaning the substrate is terminated when the Si—F stretching vibration is detected in the substrate at a level equal to or less than a first predetermined threshold. Etching method.

2. 2. The etching method according to claim 1, stopping the supply of water vapor when the Si—F stretching vibration is detected to be equal to or less than the threshold value; and removing the substrate from the processing chamber after stopping the supply of water vapor. Etching method.

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

4. 4. The etching method according to claim 1, the step of cleaning the substrate is terminated when the Si—F stretching vibration equal to or greater than a predetermined second threshold is detected in the substrate, and then the Si—F stretching vibration equal to or less than the first threshold is detected in the substrate. Etching method.

5. 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 Si—F 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 etching gas supply unit so that the etching gas is supplied into the processing chamber in the reduced pressure state; controlling the water vapor supply unit so that the water vapor is supplied into the processing chamber after the etching gas is supplied; controlling the detection unit so that the Si—F stretching vibration is detected in the processing chamber to which the water vapor is supplied; controlling the water vapor supply unit so that the supply of water vapor is stopped when the Si—F stretching vibration is detected in the substrate at a level equal to or less than a predetermined threshold value; Etching equipment.

6. 6. The etching apparatus according to claim 5, 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.

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