Spin etching apparatus with end point detection mechanism and spin etching method

Abstract

To provide a spin etching device with an endpoint detection mechanism capable of stably detecting an endpoint of wet etching regardless of a difference in a thickness of an AI coating layer (variation of about 3 to 5 μm) and a little fluctuation of an etching rate depending on each product and a spin etching method.SOLUTION: A spin etching device with an endpoint detection mechanism includes: a rotary table on which an AI coated substrate comprising an AI coating layer on a substrate main body is mounted; an annular hood for liquid medicine dispersion prevention installed at an upper side of the rotary table and formed from a material, through which visible light is permeable, for preventing an etchant from being dispersed; an etchant nozzle which blows the etchant onto a surface of the AI coated substrate on the rotary table by a shower system; and an invisible light spectral instrument for irradiating the surface of the AI coated substrate with invisible light and detecting a spectrum of the invisible light reflected by the AI coated substrate. An endpoint of etching to the AI coating layer is detected from a change in the spectrum of the invisible light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology for detecting the endpoint of a wet etching process, and in particular to a technology for detecting the endpoint when an aluminum film formed on the surface of a sample is etched. For example, the present invention relates to a spin etching apparatus with an endpoint detection mechanism and a spin etching method when an aluminum film formed on a substrate is wet etched in a semiconductor manufacturing process. [Background technology]

[0002] In semiconductor device manufacturing processes, aluminum (Al) is used as the final electrode formed on a wafer, and the electrode is formed by etching the aluminum. An example of a method for forming an aluminum electrode by etching aluminum is shown in FIG. 5. In FIG. 5, (a) shows the state before etching, and (b) shows the state after etching. In FIG. 5, reference numeral 116 denotes a semiconductor substrate. As shown in FIG. 5(a), an insulating film 114, an aluminum material 112, and a resist 110 are formed on a semiconductor substrate 116 such as silicon, and then the aluminum material 112 is etched to form an aluminum electrode 120 [FIG. 5(b)].

[0003] In the case of general semiconductor devices, the thickness of the aluminum electrode is 1 μm or less, so dry etching is effective for etching the aluminum film. On the other hand, in power devices such as silicon power semiconductors, the thickness of the aluminum electrode can be as much as 5 μm. Figure 6 shows an example of a power semiconductor device. Figure 6 shows an example of a silicon power semiconductor as the power semiconductor device. As shown in Figure 6, in a silicon power semiconductor wafer 100, the edge exclusion regions, which are numerous at the outer periphery 102 of the wafer 100, are also large, and therefore the aluminum needs to be etched accordingly.

[0004] Dry etching takes a long time to etch such a thick aluminum film, so wet etching is generally used for thick aluminum films.

[0005] For example, Patent Document 1 discloses a method for detecting the end point of wet etching using light.

[0006] The aluminum electrodes in the power devices mentioned above are thick, and if the aluminum is wet etched without the shower method, the etching rate will be low and the yield will be poor, so shower wet etching is used. In shower wet etching, the etchant is a phosphonitric acid acetic acid solution heated to about 60°C, and the etchant must be evenly supplied to the surface of the rotating substrate (wafer) using a shower. Supplying the etchant using this shower method ensures a high etching rate, but it also means that the etchant will splash around.

[0007] To prevent the etching solution from scattering, it is necessary to cover the area around the rotating substrate with an annular hood to prevent the etching solution from scattering during etching.

[0008] Thus, when etching is performed by the shower method using an annular hood to prevent scattering of the chemical solution and the end point is detected by light from a light source, there is a problem that an error may occur in the detection. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 10-36981 Summary of the Invention [Problem to be solved by the invention]

[0010] The inventors have conducted extensive research into the causes of detection errors when the shower etching method is performed with the annular hood for preventing chemical solution scattering and the endpoint is detected using light from a light source. As a result, they have found that, in conventional methods where endpoint detection is performed using visible light as the light source, water droplets of the etching solution adhering to the annular hood for preventing chemical solution scattering flow, causing scattered light and resulting in false detection, and have arrived at this invention.

[0011] That is, the present invention has been made in consideration of the above-mentioned problems of the conventional technology, and aims to provide a spin etching apparatus with an end-point detection mechanism and a spin etching method that enable stable detection of the end point of wet etching regardless of differences in the thickness of the Al coating layer between products (variations of about 3 to 5 μm) and slight fluctuations in the etching rate. [Means for solving the problem]

[0012] In order to solve the above-mentioned problems, the present invention provides a spin etching apparatus with an endpoint detection mechanism that includes a turntable on which an Al-coated substrate having an Al coating layer on a substrate body is placed, an annular hood for preventing chemical solution splashing that is installed above the turntable and is made of a material that transmits visible light and that prevents the etching solution from splashing, an etching solution nozzle that sprays the etching solution onto the surface of the Al-coated substrate on the turntable in a shower manner, and an invisible light spectroscope that irradiates the surface of the Al-coated substrate on the turntable with invisible light and detects the spectrum of the invisible light reflected by the Al-coated substrate, and that detects the endpoint of etching of the Al coating layer based on a change in the spectrum of the invisible light.

[0013] The thickness of the Al coating layer is preferably 5 μm or more.

[0014] The invisible light is preferably infrared or ultraviolet light.

[0015] It is preferable that an underlayer selected from at least one of the group consisting of SiO2, TiN, Au, and Ag is formed between the substrate body and the Al coating layer, and the end point of etching into the Al coating layer is detected by detecting the spectrum of the underlayer.

[0016] The position at which the etching end point is detected in the spin etching apparatus with an end point detection mechanism is preferably 20 to 30 mm from the surface of the Al-coated substrate.

[0017] The infrared spectrometer preferably comprises a light source for irradiating invisible light, a detector for detecting the invisible light reflected by the surface of the Al coating layer, a spectroscope for spectroscopically analyzing the invisible light reflected by the surface of the Al coating layer, and a coaxial fiber having an optical fiber section for transmitting the invisible light from the light source to the detector and an optical fiber section for transmitting the invisible light reflected by the surface of the Al coating layer detected by the detector to the spectroscope, and the detection spot diameter of the detector is preferably 10 to 20 mm.

[0018] It is preferable that the coaxial fiber is coated with a chemical-resistant resin, and that N2 purge is performed to prevent the etching solution atmosphere from entering from the tip of the detector on the inspection spot side.

[0019] It is preferable that the detection of the end point of etching into the Al coating layer is performed at least in the edge exclusion region of the Al coating substrate.

[0020] The spin etching method of the present invention is a spin etching method using the spin etching apparatus with an end point detection mechanism, and includes the steps of: etching the surface of an Al-coated substrate having the Al coating layer placed on the turntable by spraying an etching solution onto the surface of the Al-coated substrate in a shower manner while rotating the turntable; and irradiating the surface of the Al-coated substrate on the turntable with invisible light and detecting the end point of etching of the Al coating layer based on a change in the spectrum of the invisible light reflected by the Al-coated substrate.

[0021] The invisible light is preferably infrared or ultraviolet light.

[0022] It is preferable that the detection of the end point of etching into the Al coating layer is performed at least in the edge exclusion region of the Al coating substrate.

[0023] The detection of the end point of etching into the Al coating layer is preferably carried out at a point where the line width between each chip after etching of the Al coating substrate is 0.5 mm or more and 1.5 mm or less. [Effects of the Invention]

[0024] The present invention has the remarkable effect of providing a spin etching apparatus with an end point detection mechanism and a spin etching method that can stably detect the end point of wet etching regardless of differences in the thickness of the Al coating layer between products (variations of about 3 to 5 μm) and slight fluctuations in the etching rate. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a structural diagram showing one embodiment of a spin etching apparatus with an end point detection mechanism of the present invention. [Figure 2] 1 is a side view showing one embodiment of a spin etching apparatus with an end point detection mechanism of the present invention. [Figure 3] 1 is a plan view showing one embodiment of a spin etching apparatus with an end point detection mechanism of the present invention. [Figure 4] 1 is a schematic diagram illustrating an example of an infrared spectrometer used in a spin etching apparatus with an end point detection mechanism according to the present invention. [Figure 5] 1A to 1C are schematic diagrams illustrating an example of a method for forming an aluminum electrode by etching an aluminum material. [Figure 6] FIG. 1 is a schematic diagram illustrating an example of a power device semiconductor. [Figure 7] FIG. 1 is a diagram showing the configuration of an example of a conventional spin etching apparatus that detects an end point using visible light. [Figure 8] 1 is a graph showing the difference in the reflection spectra of aluminum, Si, and SiO 2 at a wavelength of 913.6 nm, where (a) shows the reflection spectrum of aluminum, and (b) shows the reflection spectrum of aluminum, Si, and SiO 2 at a wavelength of 913.6 nm. [Figure 9] 1 is a graph showing the reflection spectra of Al, Ag, and Au. [Figure 10] 1 is a graph showing the difference in the reflection spectra of aluminum, TiN, and SiC+SiO2 at a wavelength of 297.6 nm, where (a) shows the reflection spectrum of aluminum, and (b) shows the reflection spectrum of aluminum, TiN, and SiC+SiO2 at a wavelength of 297.6 nm. [Figure 11] 1 is a graph showing the difference in the reflection spectra of aluminum, TiN, and SiC+SiO2 at a wavelength of 297.6 nm, where (a) shows the reflection spectrum of TiN, and (b) shows the reflection spectrum of aluminum, TiN, and SiC+SiO2 at a wavelength of 297.6 nm. [Figure 12] 1 is a graph showing the difference in the reflection spectra of aluminum, TiN, and SiC+SiO2 at a wavelength of 297.6 nm, where (a) shows the reflection spectrum of SiC+SiO2, and (b) shows the reflection spectrum of aluminum, TiN, and SiC+SiO2 at a wavelength of 297.6 nm. [Figure 13] 1 is a graph showing changes in the reflectance spectrum during etching at a wavelength of 940 nm in Example 1. [Figure 14] 1 is a graph showing a reflection spectrum when detecting an end point in Example 1. [Figure 15] 1 is a graph showing changes in the reflection spectrum during etching at a wavelength of 450 nm in Comparative Example 1. [Figure 16] 10 is a graph showing a reflection spectrum when detecting an end point in Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0026] The following describes embodiments of the present invention, but these embodiments are shown by way of example only, and it goes without saying that various modifications are possible without departing from the technical spirit of the present invention. In the drawings, the same members are designated by the same reference numerals.

[0027] 1 to 3 show one embodiment of the spin etching apparatus with an endpoint detection mechanism of the present invention. In FIGS. 1 to 3, the reference numeral 10 denotes the spin etching apparatus with an endpoint detection mechanism of the present invention. The spin etching apparatus with an endpoint detection mechanism of the present invention includes a turntable 12 on which an Al-coated substrate having an Al coating layer on a substrate body is placed, an annular hood 14 for preventing the etching solution from splashing, which is disposed above the turntable 12 and is made of a material that transmits visible light, and which prevents the etching solution from splashing, an etching solution nozzle 16 for spraying the etching solution onto the surface of the Al-coated substrate on the turntable 12 in a shower-like manner, and an invisible light spectrometer 18 for irradiating the surface of the Al-coated substrate on the turntable 12 with invisible light and detecting the spectrum of the invisible light reflected by the Al-coated substrate, and the endpoint of etching of the Al coating layer is detected by a change in the spectrum of the invisible light. In FIG. 3, the area indicated by the symbol A is the etching stage, the area indicated by the symbol B is the rotation standby position, and the area indicated by the symbol C is the rinse shower area.

[0028] The spin etching apparatus 10 with an end point detection mechanism of the present invention is used for etching aluminum, in which the end point of etching is defined as the state in which the etched area of ​​the Al coating layer is completely removed by forming a pattern through etching, and the layer below the Al coating layer (made of a material with a different invisible light spectrum from the Al coating layer) is exposed. In the spin etching apparatus 10 with an end point detection mechanism of the present invention, while the Al coating layer of an Al coated substrate is being etched, invisible light is irradiated onto the surface of the Al coated substrate and the spectrum of the invisible light reflected by the Al coated substrate is detected. When the lower layer of the Al coating layer is exposed and etching is completed, the spectrum of the invisible light changes, and the end point of etching of the Al coating layer can be detected from the change in the spectrum of the invisible light.

[0029] There are no particular limitations on the turntable 12, and any known turntable used in a spin etching apparatus can be used.

[0030] There are no particular limitations on the annular hood 14 for preventing chemical solution splashing, as long as it is made of a material that transmits visible light, and any known annular hood for preventing etching solution splashing can be used. In aluminum wet etching, in which etching solution is sprayed onto the surface of an Al-coated substrate in a shower manner while rotating the turntable 12, the use of the annular hood 14 for preventing chemical solution splashing can prevent the etching solution from splashing to the periphery and ensure an etching rate by evenly supplying the etching solution to the surface of the rotating Al-coated substrate.

[0031] By using the spin etching apparatus 10 with an endpoint detection mechanism, rapid spin etching can be achieved even when etching thick Al coating layers of 5 μm or more. Specifically, the spin etching rate can be 13,000 Å / min or more. Furthermore, the thickness of the Al coating layer varies depending on the product. For example, a product difference of 3 to 5 μm can vary from 3 μm to 3.5 μm, and even 5 μm to 5 μm. However, the present invention is suitable for etching thick Al coating layers, and can stably detect the wet etching endpoint even when the Al thickness varies from product to product, such as 3 to 5 μm, or when the etching rate fluctuates slightly.

[0032] The etching solution nozzle 16 is not particularly limited as long as it can spray the etching solution onto the Al-coated substrate surface on the turntable 12 in a shower manner, and known etching solution nozzles used in spin etching devices can be used. A wide variety of known etching solutions used for etching aluminum can be used as the etching solution. Examples include acidic etching solutions containing acids such as phosphoric acid and nitric acid. Acidic etching solutions such as phosphonitric acid-acetic acid containing phosphoric acid, nitric acid, and acetic acid (e.g., 76-81% phosphoric acid, 2-4% nitric acid, 2-4% acetic acid, the balance water) are preferably used. The etching solution is preferably heated to a predetermined temperature. The heating temperature of the etching solution is not particularly limited, but 55-65°C is preferred.

[0033] 4 shows an example of the invisible light spectroscope 18 used in the spin etching apparatus 10 with an endpoint detection mechanism of the present invention. The invisible light spectroscope 18 is not particularly limited as long as it is an invisible light spectroscope that can irradiate the surface of the Al-coated substrate 28 on the turntable 12 with invisible light and detect the spectrum of the invisible light reflected by the Al-coated substrate. However, as shown in FIGS. 1 and 4, the invisible light spectroscope 18 preferably includes a light source 20 for irradiating invisible light (excitation light X), a detector 24 for detecting invisible light (fluorescence Y) reflected by the Al-coated substrate surface, a spectroscope 26 for spectroscopically analyzing the fluorescence Y, and a coaxial fiber 22 having an optical fiber portion 22a for transmitting the excitation light X from the light source 20 to the detector 24 and an optical fiber portion 22b for transmitting the fluorescence Y detected by the detector 24 to the spectroscope 26. By using invisible light as the light source 20 and separating the light from the spectrometer 26 using the coaxial fiber 22, the end point of wet etching can be detected more stably and accurately. In FIGS. 1 and 4, an example is shown in which an IR-LED light emitting infrared ray with a wavelength of approximately 940 nm is used as the light source 20 that emits invisible light. The photodetector 24 is preferably installed at a slight inclination from the vertical direction, and preferably at an inclination of 1° to 25° from the vertical to the horizontal plane. In the example of FIG. 1, the photodetector 24 is installed at an inclination of 15°.

[0034] In the present invention, the endpoint detection mechanism uses invisible light, which has wavelengths not found in typical indoor environments, thereby avoiding scattered light. When visible light is used, there is a problem that external light can affect the annular hood for preventing chemical solution splashing, causing water droplets (such as etching solution) to adhere to and flow through the annular hood, resulting in scattered light and causing false detection. In the present invention, by providing an annular hood for preventing chemical solution splashing 14 to prevent the etching solution from splashing and using invisible light, the chemical solution is prevented from splashing into the surrounding area, scattered light is avoided, and the endpoint can be detected stably and accurately.

[0035] The invisible light irradiated from the light source 20 may be selected from the invisible light wavelength range depending on the material of the layer below the Al coating layer that is exposed at the end of etching, so that the wavelength at which the reflectance of Al and the layer below the Al coating layer differs is selected appropriately. Preferably, the invisible light is selected from infrared light with a wavelength of 780 nm to 1 mm or ultraviolet light with a wavelength of 10 nm to 380 nm. The spectrometer 26 may be selected according to the visible light to be irradiated. For example, if the invisible light is infrared, an infrared spectrometer may be used as the spectrometer 26, and if the invisible light is ultraviolet, an ultraviolet spectrometer may be used as the spectrometer 26.

[0036] While there are no particular limitations on the materials for the coaxial fiber 22 and the detector 24, it is preferable that they be coated with a chemical-resistant resin and that N2 purge be performed to prevent the etching solution atmosphere from entering the tip of the detector 24 on the inspection spot side. By using a chemical-resistant resin coating, the detection distance can be set near the surface of the Al-coated substrate 28 inside the annular hood 14 for preventing chemical solution splashing, as the position for detecting the etching endpoint, allowing for more stable and accurate endpoint detection. There are no particular limitations on the detection distance from the surface of the Al-coated substrate 28, but it is preferable that it be approximately 20 to 30 mm from the surface of the Al-coated substrate 28. The coaxial fiber 22 preferably has a fiber wavelength range of 250 to 1200 nm. The diameter of the inspection spot of the detector 24 is not particularly limited, but is preferably 10 to 20 mm.

[0037] In the Al-coated substrate 28, the Al coating layer may be formed directly on the surface of the substrate body, or a base layer may be formed between the substrate body and the Al coating layer. Alternatively, as in the aluminum electrode shown in Figure 5, a base layer may be formed partially between the substrate body and the Al coating layer.

[0038] There is no particular limitation on the thickness of the Al coating layer, and a thick Al coating layer of 5 μm or more is also suitably used, and the thickness of the Al coating layer is more suitably 3 μm or more and 7 μm or less. The method for forming the Al coating layer is not particularly limited, and any known method for forming an Al thin film can be used, and for example, sputtering or CVD is preferable.

[0039] There are no particular limitations on the material of the substrate body used for the Al-coated substrate 28, and a wide variety of known materials used for substrates can be used. For example, semiconductor wafers such as silicon wafers and SiC wafers are suitable for the substrate body, and silicon wafers used for power device semiconductors such as IGBTs (insulated gate bipolar transistors) are more suitable.

[0040] 6, the size of one module of an IGBT pattern is large, and many edge exclusion regions exist in the outer periphery 102 of the wafer 100. In the present invention, it is preferable to detect the etching endpoint using the outer periphery 102, where many edge exclusion regions exist, as the detection area. Specifically, it is preferable that the end point of etching the Al coating layer is detected at a point where the line width between each chip after etching of the Al coating substrate is 0.5 mm or more and 1.5 mm or less.

[0041] The material of the underlayer formed between the substrate body and the Al coating layer is not particularly limited, and a wide variety of materials having a different invisible light reflection spectrum from that of the Al coating layer can be used, for example, a SiO2 layer, which is commonly used as an underlayer for aluminum, or at least one selected from the group consisting of TiN, Au, and Ag.

[0042] Next, a first embodiment of a method for spin-etching aluminum on an Al-coated substrate 28 using the spin etching apparatus 10 with an endpoint detection mechanism shown in Figures 1 to 3 will be described below. The Al-coated substrate 28 is a silicon wafer, and after forming an SiO2 layer, which is a common aluminum underlayer, on the silicon wafer, an Al coating layer is formed on the silicon wafer. As an example, aluminum is etched using a resist, as shown in Figure 5. Any known resist used for aluminum etching can be used as the resist.

[0043] Figure 8 is a graph showing the difference in the reflectance spectra of aluminum, Si, and SiO2 for infrared rays with a wavelength of 913.6 nm. In Figure 8, the infrared irradiation conditions were a wavelength of 913.6 nm, an exposure time of 100 seconds, and a measurement time of 119 seconds. Figure 8(a) shows the reflectance spectrum indicating intensity versus frequency for aluminum, and Figure 8(b) shows the spectra indicating the intensity of aluminum, Si, and SiO2 at a wavelength of 913.6 nm [X-axis: time (seconds), Y-axis: intensity]. As shown in FIG. 8(b), infrared rays pass through Si and SiO2 but not through aluminum.

[0044] As shown in Figure 5, before etching, an Al coating layer and resist are present on the surface of the Al-coated substrate, but after etching is completed, the etched areas where there is no resist are left with an exposed SiO2 layer. As shown in Figure 8, Si and SiO2 have different reflectance spectra at specific wavelengths (e.g., infrared light with wavelengths of 910 to 950 nm) than aluminum, so infrared light of a specific wavelength is irradiated during etching, and the reflectance spectrum is measured using an infrared spectrometer. By observing the change in intensity, the change from aluminum to SiO2 can be detected, and the point where the intensity changes abruptly can be used to determine the end point of etching.

[0045] Fig. 9 is a graph showing the reflectance spectra of Al, Ag, and Au. As shown in Fig. 9, Al reflects light evenly in the wavelength range of 200 nm to 5 μm, while Ag and Au absorb light in the ultraviolet region. Therefore, for an Al-coated substrate using Ag or Au as an underlayer, ultraviolet light of a specific wavelength (e.g., wavelength 200 nm to 380 nm) absorbed by the underlayer is used as a light source, and the reflectance spectrum is measured with an ultraviolet spectrometer. By observing the change in intensity, the change from aluminum to Ag or Au can be detected, and the position where the intensity changes abruptly can be used as the end point to detect the etching end point.

[0046] Next, a second embodiment of the method for spin-etching aluminum on an Al-coated substrate 28 using the spin etching apparatus 10 with an endpoint detection mechanism shown in Figures 1 to 3 will be described below. As the Al-coated substrate 28, a SiC wafer is used as the substrate body. A TiN layer is formed as an underlayer on the SiC wafer, followed by an Al coating layer, to form an Al-coated substrate for an aluminum electrode. As shown in Figure 5, an example is shown in which aluminum is etched using a resist. Any known resist used for aluminum etching can be used as the resist.

[0047] Figures 10 to 12 are graphs showing the differences in the reflectance spectra of aluminum, TiN, and SiC+SiO2 under ultraviolet light with a wavelength of 297.6 nm. In Figures 10 to 12, the ultraviolet light irradiation conditions were a wavelength of 297.6 nm, an exposure time of 100 seconds, and a measurement time of 100 seconds. Figure 10(a) shows the reflectance spectrum showing intensity versus frequency for aluminum, Figure 11(a) shows the reflectance spectrum showing intensity versus frequency for TiN, Figure 12(a) shows the reflectance spectrum showing intensity versus frequency for SiC+SiO2, and Figures 10(b) and 12(b) show the spectra showing intensity of aluminum, TiN, and SiC+SiO2 at a wavelength of 297.6 nm [X-axis: time (seconds), Y-axis: intensity]. As shown in Figs. 10 to 12, aluminum, TiN, and SiC+SiO2 had an intensity difference of 300,000 or more against ultraviolet light.

[0048] Therefore, by irradiating invisible light of a specific wavelength during etching, measuring the reflection spectrum with an invisible light spectrometer, and observing the change in intensity, it is possible to detect the change from aluminum to TiN and SiC+SiO2, and the point where the intensity changes suddenly can be used to detect the etching end point. In particular, as shown in Figures 10 to 12, aluminum, TiN, and SiC+SiO2 have very large differences in intensity relative to ultraviolet light, making it more effective to use ultraviolet light to detect the end point.

[0049] As described above, the spin etching method of the present invention is achieved by performing spin etching on an Al-coated substrate having an Al coating layer using the spin etching apparatus 10 with an end point detection mechanism. Specifically, the spin etching method of the present invention includes the steps of: etching the Al-coated substrate surface by spraying an etching solution onto the Al-coated substrate surface in a shower manner while rotating the turntable, with respect to the Al-coated substrate having the Al coating layer, which is placed on the turntable; and irradiating the Al-coated substrate surface on the turntable with invisible light and detecting the end point of etching of the Al coating layer based on a change in the spectrum of the invisible light reflected by the Al-coated substrate. [Example]

[0050] Example 1 Using the spin etching apparatus with endpoint detection mechanism of the present invention, configured as shown in Figure 1, aluminum wet etching was performed while irradiating it with infrared light and measuring the reflectance spectrum. Specifically, an Al-coated substrate with an Al coating layer was placed on a turntable. While the turntable was rotating at 800 to 1500 rpm, an etching solution (phosphorus, nitric acid, and acetic acid, at 65°C) was sprayed onto the Al-coated substrate surface using a shower method to etch the Al-coated substrate surface. An infrared spectrometer (light source: 940 nm wavelength) equipped with a coaxial fiber and detector (detection spot diameter: approximately 10 mm) as shown in Figure 4 was used as the non-visible light spectrometer. Infrared light (excitation light) was irradiated onto the Al-coated substrate surface on the turntable at a distance of approximately 20 mm from the detector at the tip of the fiber. The fluorescence reflected by the Al-coated substrate was measured, and the change in the infrared spectrum was observed. The endpoint of etching was determined by the point where the intensity suddenly decreased. The results are shown in Figures 13 and 14. As shown in FIG. 6, the measurement points on the Al-coated substrate were in the edge exclusion region of the outer periphery 102, at locations where the line width between chips after etching was 5 mm or more.

[0051] An Al-coated substrate was prepared by partially forming an SiO2 layer (approximately 0.3 μm thick) as an underlayer on a silicon wafer [diameter 200 mm (8 inches), thickness 725 μm] by CVD as shown in Figure 5. Then, an Al-coated layer (5 μm thick) was formed by CVD on the Al-coated substrate for aluminum electrodes. Aluminum spin etching was performed using a resist as shown in Figure 5. The etching rate was 15,000 Å / min.

[0052] Fig. 13 is a graph showing the change in the reflection spectrum during etching at a wavelength of 940 nm in Example 1. As shown in Fig. 13, the intensity of the reflection spectrum dropped suddenly during etching, so the position where the intensity suddenly dropped was detected as the endpoint. Fig. 14 is a graph showing the reflection spectrum when the endpoint was detected in Example 1. At the time of endpoint detection, the aluminum in the etching area on the Al-coated substrate surface had been removed, exposing the SiO2 layer, allowing accurate wet etching endpoint detection. Therefore, the present invention enabled stable wet etching endpoint detection without reducing the etching rate, without being affected by diffuse reflection, and preventing false detection due to scattered light.

[0053] (Comparative Example 1) Aluminum spin etching was performed on an Al-coated substrate in the same manner as in Example 1, except that a conventional spin etching apparatus for detecting the end point using visible light, as shown in FIG. 7, was used. In Fig. 7, reference numeral 104 denotes a conventional spin etching apparatus, which irradiates visible light from a visible light source 122 (a composite wavelength of visible light from an LED fluorescent lamp and sunlight) from the outside of an annular hood 14 that transmits visible light, directly detects the visible light fluorescence reflected from the Al-coated substrate with a detector 124 provided outside the annular hood 14, and measures the change in the spectrum at a wavelength of 450 nm with a spectrometer 126. The results are shown in Figs. 15 and 16.

[0054] When visible light is used, detection occurs in a state where diffuse reflection occurs, which generates noise as shown in Figure 15, and endpoint detection using the spectrum is prone to false detection. [Explanation of symbols]

[0055] 10: spin etching apparatus with end point detection mechanism of the present invention, 12: rotary table, 14: annular hood for preventing chemical solution from scattering, 16: etching solution nozzle, 18: invisible light spectroscope, 20: light source, 22, 22a, 22b: coaxial fiber, 24: detector, 26: spectroscope, 28: Al-coated substrate, 100: silicon power semiconductor wafer, 102: outer periphery of wafer, 104: conventional spin etching apparatus, 110: resist, 112: aluminum material, 114: insulating film, 116: semiconductor substrate, 120: aluminum electrode, 122: visible light source, 124: detector, 126: spectroscope, 130: optical fiber, A: etching stage, B: rotating standby position, C: rinse shower area, X: excitation light, Y: fluorescence.

Claims

1. a rotary table on which an Al-coated substrate having an Al coating layer on a substrate body is placed; an annular hood for preventing scattering of the etching solution, the annular hood being disposed above the rotary table and being made of a material that transmits visible light, for preventing scattering of the etching solution; an etching solution nozzle for spraying an etching solution onto the surface of the Al-coated substrate on the rotary table in a shower manner; an invisible light spectrometer for irradiating an invisible light beam onto the surface of the Al-coated substrate on the rotary table and detecting the spectrum of the invisible light beam reflected by the Al-coated substrate; Including, The end point of etching of the Al coating layer is detected based on a change in the spectrum of the invisible light. Spin etching equipment with end point detection mechanism.

2. 2. The spin etching apparatus with an end point detection mechanism according to claim 1, wherein the thickness of said Al coating layer is 5 [mu]m or more.

3. 2. The spin etching apparatus with an end point detection mechanism according to claim 1, wherein the invisible light is infrared or ultraviolet light.

4. Between the substrate body and the Al coating layer, SiO ２ 2. A spin etching apparatus with an end point detection mechanism as described in claim 1, wherein an underlayer selected from at least one of the group consisting of TiN, Au, and Ag is formed, and the end point of etching of the Al coating layer is detected by detecting the spectrum of the underlayer.

5. 2. The spin etching apparatus with an end point detection mechanism according to claim 1, wherein the position at which the etching end point is detected in said spin etching apparatus with an end point detection mechanism is 20 to 30 mm from the surface of said Al-coated substrate.

6. 2. The spin etching apparatus with an endpoint detection mechanism according to claim 1, wherein the invisible light spectroscopic device comprises: a light source for irradiating invisible light; a detector for detecting invisible light reflected by the surface of the Al coating layer; a spectroscope for spectroscopically analyzing the invisible light reflected by the surface of the Al coating layer; and a coaxial fiber having an optical fiber section for transmitting the invisible light from the light source to the detector and an optical fiber section for transmitting the invisible light reflected by the surface of the Al coating layer detected by the detector to the spectroscope, and wherein the detection spot diameter of the detector is 10 to 20 mm.

7. The coaxial fiber is coated with a chemical-resistant resin, and N is used to prevent the etching solution atmosphere from entering from the tip of the detector on the inspection spot side. ２ 7. The spin etching apparatus with an end point detection mechanism according to claim 6, wherein purging is performed.

8. 2. The spin etching apparatus with an end point detection mechanism according to claim 1, wherein the end point of etching into said Al coating layer is detected at least in an edge exclusion region of said Al coating substrate.

9. A spin etching method using the spin etching apparatus with an end point detection mechanism according to any one of claims 1 to 8, a step of spraying an etching solution onto a surface of the Al-coated substrate having the Al coating layer placed on the turntable in a shower manner while rotating the turntable, thereby etching the surface of the Al-coated substrate; a step of irradiating an invisible light beam onto the surface of the Al-coated substrate on the rotary table and detecting an end point of etching of the Al-coated layer based on a change in the spectrum of the invisible light beam reflected by the Al-coated substrate; A spin etching method comprising:

10. The spin etching method according to claim 9, wherein the invisible light is infrared or ultraviolet light.

11. 10. The spin etching method according to claim 9, wherein the detection of the end point of etching into the Al coating layer is performed at least in an edge exclusion region of the Al coating substrate.

12. 10. The spin etching method according to claim 9, wherein the end point of etching the Al coating layer is detected at a point where the line width between each chip after etching of the Al coating substrate is 0.5 mm or more and 1.5 mm or less.

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