Bath system and method thereof

Abstract

A method for processing a plurality of substrates includes immersing a plurality of substrates in a bath solution contained in a bath, generating gas bubbles in the bath solution, projecting light from a light source toward the bath, generating light sensor data by capturing light emitted from the bath after interaction with the gas bubbles with a light sensor, and converting the light sensor data into a metric of the bath solution.

Description

[Technical Field]

[0001] Cross-reference of related patents and applications This application claims priority on the filing date of U.S. Nonprovisional Patent Application No. 17 / 341,105, filed on June 7, 2021, the entire text of said application is incorporated herein by reference.

[0002] Technical field The present invention generally relates to systems and methods for monitoring bath treatment, and in embodiments, to bath systems and methods thereof. [Background technology]

[0003] Wafer baths with circulating fluids are commonly used in semiconductor manufacturing to simultaneously perform substrate surface preparation steps, such as surface cleaning, resist stripping, and thin film etching, on batches of multiple wafers.

[0004] Uniformity across and between wafers is crucial for providing integrated circuit components such as transistors, capacitors, and resistors that have a narrow electrical distribution across all wafers in a lot. Achieving uniformity across and between wafers in a bath is difficult for large-diameter wafers, such as 12-inch wafers.

[0005] Insufficient cleaning or etching of the substrate in the surface preparation bath can result in reduced yield due to residual resist or thin film on the wafer, or due to non-uniformity of the etched thin film on the wafer. Excessive cleaning increases cycle time and generates excessive hazardous waste. Excessive cleaning can also reduce yield if excessive etching causes the thin film thickness or critical dimensions to deviate from the target. [Overview of the project] [Means for solving the problem]

[0006] In one embodiment, a method for processing multiple substrates includes immersing the multiple substrates in a bath solution contained in a bathtub, generating bubbles in the bath solution, projecting light from a light source toward the bathtub, generating optical sensor data by capturing the light emitted from the bathtub after interaction with the bubbles using an optical sensor, and converting the optical sensor data into a metric of the bath solution.

[0007] In one embodiment, the bath treatment tool includes a bathtub equipped with a loading arm and configured to hold a bath solution; a light source mounted on a light source mounting assembly to project light toward the bathtub; and a light sensor mounted on a sensor mounting assembly to capture light emitted from the bathtub after interaction with bubbles in the bath solution.

[0008] In one embodiment, the bath processing tool includes a bath for wet processing of wafers, an electromagnetic radiation sensor for capturing electromagnetic signals from the bath solution in the bath, a processor, and a non-temporary memory coupled to the processor for storing a program, the non-temporary memory including instructions for the program to be executed in the processor, for determining the metric of the bath solution based on the electromagnetic signals, and for identifying that a target specification for processing the wafer has been reached based on the metric of the bath solution.

[0009] In one embodiment, the endpoint detection method includes processing a wafer in a wet process, capturing an electromagnetic signal from the bath solution in the bath during processing using an electromagnetic radiation sensor, determining the endpoint metric of the bath solution based on the electromagnetic signal, and stopping the wet process in response to identifying that the endpoint of the process has been reached based on the endpoint metric of the bath solution.

[0010] In one embodiment, the process control method includes processing a wafer in a wet process, capturing electromagnetic signals from the bath solution in the bath during processing using an electromagnetic radiation sensor, determining the process target specifications of the bath solution based on the electromagnetic signals, and adjusting the bath solution according to the determination of the process target specifications based on the process target specifications of the bath solution.

[0011] To fully understand the present invention and its advantages, refer here to the following description, which should be read in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0012] [Figure 1A] This is a cross-sectional view of a bathtub equipped with a fluid injector and a gas injector according to an embodiment. [Figure 1B] This is a cross-sectional view of a bathtub equipped with a fluid injector and a heating element according to an embodiment. [Figure 2] This is a cross-sectional view of a system for monitoring and controlling a bath with bubble mixing, according to one embodiment. [Figure 3] This is a cross-sectional view of a system for monitoring and controlling a bath with bubble mixing, according to one embodiment. [Figure 4] This is a projection diagram of a system for monitoring and controlling a bath with bubble mixing, according to one embodiment. [Figure 5] This is a cross-sectional view of a system for monitoring and controlling a bath with bubble mixing, according to one embodiment. [Figure 6] This is a projection diagram of a system for monitoring and controlling a bath with bubble mixing, according to one embodiment. [Figure 7] This is a cross-sectional view of a system for monitoring and controlling a bath with bubble mixing, according to one embodiment. [Figure 8] This is a cross-sectional view of a light source for a bath with a light source integrated into a gas injector, according to one embodiment. [Figure 9] This is a cross-sectional view of a light source, including a light pipe with an internal reflector for illuminating multiple zones within a bath, according to one embodiment. [Figure 10] Projection view of a bath light source including a circular illuminator according to one embodiment. [Figure 11] Diagram of an optical sensor including a rectangular array of pixels according to one embodiment. [Figure 12] Diagram of an optical sensor including a strip of pixels according to one embodiment. [Figure 13] Projection view of a system for monitoring and controlling a bath with bubble mixing according to one embodiment. [Figure 14] Projection view of a system for determining the end point of a bath and controlling the process in the bath according to one embodiment. [Figure 15A] Diagram showing ethanol molecules and the infrared spectrum of ethanol molecules according to one embodiment. [Figure 15B] Diagram showing ethanol molecules and the infrared spectrum of ethanol molecules according to one embodiment. [Figure 16A] Diagram showing water molecules and the infrared spectrum of water molecules according to one embodiment. [Figure 16B] Diagram showing water molecules and the infrared spectrum of water molecules according to one embodiment. [Figure 17] Projection view of a system for determining the end point of a bath and controlling the process in the bath according to one embodiment.

Best Mode for Carrying Out the Invention

[0013] Although the present invention has been described with reference to exemplary embodiments, this specification is not intended to be construed in a limiting sense. Those skilled in the art will, by referring to this specification, recognize various modifications and combinations of those exemplary embodiments, as well as other embodiments of the present invention. Accordingly, the appended claims are intended to cover any such modifications or embodiments.

[0014] Embodiments of this application disclose a system and method for monitoring a bath treatment involving bubbles. Embodiments of this application disclose a method for monitoring the uniformity of mixing across a bath and the uniformity of a surface preparation process. Embodiments of this application disclose a method for accurately determining the endpoint of a treatment in a surface preparation bath.

[0015] Cross-sectional views of a bath tool 10, which includes a bathtub for a surface preparation bath 100 for processing multiple wafers 104, are shown in Figures 1A and 1B.

[0016] In Figure 1A, the surface preparation bath 100 includes an outer bath 100A and an inner bath 100B. The outer bath 100A and inner bath 100B are typically Pyrex® or quartz. The bath solution 102 flows into the bath 100 from a fluid injector 103 near the bottom of the bath 100. The bath solution 102 fills the inner bath 100B and overflows into the outer bath 100A. A wafer 104 is lowered into the bath solution 102 and supported in the bath 100 on a wafer loading arm 106. In Figure 1A, bubbles 110 (usually nitrogen) are injected into the bath solution 102 from an orifice 109 along the length of a gas injector 108 near the bottom of the bath 100. The bubbles 110 rise through the bath solution 102 faster than the bath solution 102 flows into the bath 100, providing vigorous mixing. The bubbles 110 continuously replenish the surface of the wafer 104 with the bath solution 102.

[0017] In Figure 1B, bubbles 110 are generated in the bath solution 102 by the heating element 107, which locally heats the bath solution 102 around the heating element 107, causing it to boil near the bottom of the bath 100. The localized boiling of the bath solution 102 causes bubbles to form around the heating element 107. Thus, in various embodiments, the bath tool 10 includes a bubble injector comprising a heating element 107 and / or a gas injector 108 for generating bubbles (110) in the bath solution located below the loading arm. For illustrative purposes, the heating element is shown in this arrangement, but other arrangements and other types of heating elements 107 can be used.

[0018] The heat required to boil the bath solution 102 can also be generated by exothermic reactions between reactants within the bath solution 102. For example, the temperature of a piranha bath (sulfuric acid + hydrogen peroxide) can be controlled by the rate at which hydrogen peroxide is added to the sulfuric acid. For example, the boiling temperature of a high-temperature phosphoric acid / water bath used for silicon nitride stripping can be controlled by keeping the ratio of phosphoric acid to water in the bath 100 constant.

[0019] As further shown in Figures 1A and 1B, the bath tool 10 includes a light mounting assembly 20 designed to illuminate a selected area of ​​the bath 100 and to be customized to select a specific type of light. In addition, the light mounting assembly 20 may be designed to direct light at different incident angles to the inner bath 100A and the outer bath 100B. The light mounting assembly 20 may include a mechanical system, circuitry, a controller, and one or more light sources. The bath tool 10 also includes a sensor mounting assembly 30 for detecting light scattered from the bath solution 102. The sensor mounting assembly 30 may include one or more light sensors mounted on the mechanical system and designed to detect light scattered from one or more areas of the bath solution 102. Various embodiments of the light mounting assembly 20 and the sensor mounting assembly 30 are described in further detail below.

[0020] A system for monitoring the mixing uniformity and homogeneity of the bath solution 102 across the bath by capturing and analyzing light scattered from the bubbles 110 is shown in Figure 2.

[0021] Light sources 112 project light into the bath 100. Multiple light sources 112 can project light into multiple zones across the length and width of the bath 100. Light scattered from bubbles 110 can be captured by a light sensor 114 or multiple light sensors 114. The amount of light scattered from bubbles 110 in a first zone of the bath 100 can be compared with the amount of light scattered from bubbles in a second zone to determine the uniformity between zones across the bath 100. Various bubble characteristics indicating the state and uniformity of the bath solution 102 can be calculated from the light sensor data. These bubble characteristics include static bubble number density and size density, dynamic bubble number density and size density, static bubble uniformity, dynamic bubble uniformity, bath solution uniformity, and bubble generation rate.

[0022] In Figure 2, the light source 112 and the photosensor 114 are positioned below the bath 100 and are mounted, for example, to the optical mounting assembly 20 and the sensor mounting assembly 30, respectively. The light source 112 may be an LED or a laser. The photosensor 114 may be a charge-coupled device (CCD) camera with an array of CCD pixels, a complementary metal-oxide-semiconductor (CMOS) image sensor with an array of CMOS pixels, or the photosensor 114 may be a photodiode or an array of photodiode pixels. The photosensor 114 can transmit optical data to the processor 180 for analysis. The processor 180 may be a controller for the bath tool 10 or a common controller for the tool group. The processor 180 may increase or decrease the flow of gas from the gas injector 108 to improve the uniformity of the mixture across the inner bath 100B. The processor 180 may increase or decrease the amount of fluid injected into the bath 100 from the fluid injector 103. The processor 180 can also adjust the intensity of the light source 112, turn the light source 112 on and off, and synchronize the light source 112 with the light sensor 114. The processor 180 can increase or decrease the power to the heating element 107 to increase or decrease boiling. The processor 180 can adjust the flow of components that cause an exothermic reaction to control the temperature of the bath 100. For example, increasing the reaction rate of the exothermic reaction can cause localized heating within the bath 100, leading to boiling of the bath solution 102, thereby increasing the formation of detectable bubbles.

[0023] Figure 3 shows an alternative embodiment in which a light sensor 114, positioned diagonally from the light path from the light source 112 to the bath, captures scattered light.

[0024] As illustrated, in various embodiments, the light source 112 in Figure 3 is, for example, uniformly distributed across the underside of the bath 100. A photosensor 114, oriented toward the side of the bath 100, captures light scattered horizontally from the bubbles 110 from the side of the bath 100. In one embodiment, the photosensor 114 is positioned perpendicular to the path of light from the light source 112 into the bath 100. In other embodiments, the photosensor 114 may be positioned elsewhere to capture light scattered from the bath 100 at different angles. In one embodiment, while light is irradiated from the light source 112, the photosensor 114 can be scanned horizontally or vertically, for example, from the bottom to the top of the bath 100, to acquire video or a series of images. The acquired video or series of images can then be analyzed together to determine various bubble parameters, which can then be used to improve the uniformity of the bath and other process metrics.

[0025] In various embodiments, the light sources 112 may have different wavelengths (colors). Light sources 112 of different colors can illuminate different zones within the bath 100. The light sensor 114 may be a CCD camera, a CMOS image sensor, or a photodiode array with color filters for separating light of different colors. This method can eliminate intensity errors that occur when light from two or more light sources 112 scatters from the same bubble 110. Bubble characteristics from two adjacent zones can be compared without interference using this method.

[0026] The light source 112 can cycle on and off in synchronization with or together with the light sensor 114. By changing the frequency, duty cycle, and power of the light source 112, a flash of light similar to a strobe light can be generated. The flash of light allows the light sensor 114 to capture a clear still image of the bubbles 110. The static bubble patterns can be analyzed to compare bubble sizes in various bath zones and to determine the bubble uniformity and density across and between zones. A series of static bubble patterns can be photographed and analyzed over time to determine changes in bubble uniformity and density in the zones. By alternately flashing the first light source 112 and the second adjacent light source 112, the uniformity of the bath solution 102 in two adjacent bath zones can be determined without interference.

[0027] As an example, in the configuration shown in Figure 3, the uniformity of the mixture in the corresponding zones on the upper left and upper right halves of wafer 104 can be analyzed by comparing the light scattered from the bubbles 110 in the first zone on the upper left half of the wafer with the light scattered from the bubbles 110 in the second zone on the right half of the wafer. In the configuration of Figure 3, light from the first light source 112A below the first zone is scattered horizontally from the bubbles into the first photosensor 114A, which is directed to the left side of the bath 100. Light from the second light source 112B below the second zone is scattered horizontally from the bubbles into the second photosensor 114B, which is directed to the right side of the bath 100.

[0028] Figure 4 shows a projection view of a bath tool according to one embodiment. The bath tool in Figure 4 shows a configuration for analyzing and monitoring the mixing uniformity in the bath solution 102 by capturing light reflected from droplets released into the air above the surface of the bath 100 as bubbles 110 rise to the surface and burst. A laser 116 can sweep a beam of laser light above the surface of the bath solution 102, forming a plane of laser light 118 (over time). Laser light scattered from droplets released from bursting bubbles can be captured by an optical sensor 114 above the plane of laser light 118. The optical sensor 114 may be a CCD camera or a photodiode camera. The intensity and uniformity of the light captured by individual pixels 152 (Figure 11) of a CCD or photodiode pixel array 150 can be analyzed to determine the uniformity and velocity of bubbles 110 bursting across the surface of the bath solution 102. The processor 180 can increase or decrease the gas injection rate from the gas injectors 108 to increase or decrease mixing, and can balance the bubbles 110 released from the individual gas injectors 108 to improve the uniformity of mixing across the bath 100. Alternatively, the processor 180 can increase or decrease the power to the heating elements 107 to increase or decrease mixing, and can balance the bubbles 110 formed around the individual heating elements 107 to improve the uniformity of mixing across the bath 100. The processor 180 can adjust the flow of components in the exothermic reaction to control the temperature of the bath 100, and therefore boiling. Figure 5 shows a cross-sectional view of a bath tool according to one embodiment.

[0029] In Figures 2 and 3, the light source 112 is positioned to monitor the uniformity of the bath mixture across the width of the bath 100. The light source 112 illuminates multiple bath zones across the main surface of the wafer.

[0030] In another embodiment shown in Figure 5, a light source 112 is positioned to monitor the uniformity of the bath mixture along the length of the bath 100. The light source 112 illuminates multiple bath zones along the length of the gas injector 108, or multiple zones along the length of the heating element 107. The light source 112 illuminates the corresponding surface areas on all wafers 104 in the batch. Bubbles 110 are emitted from an orifice 109 along the length of the gas injector 108, or from a hot surface along the length of the heating element 107. The wafers 104 in the batch are lined up along the gas injector 108 and spaced apart above the gas injector 108 on the wafer loading arm 106. In Figure 5, a light sensor 114 is located below the bath 100. The light sensor 114 captures light reflected from bubbles rising between the wafers 104. Alternatively, the light sensor 114 may be positioned to capture light scattered from the side of the bath 100, as shown in Figure 3.

[0031] Figure 6 shows a projection view of a bath tool according to one embodiment.

[0032] In the configuration shown in Figure 6, the laser beam 124 is projected into the bathtub and redirected toward the photosensor 114 by the prism 122. The prism 122 can be positioned at any convenient location within the bathtub 100. In Figure 5, the prism 122 serves a dual purpose: for refraction of light and as a wafer loading arm 106.

[0033] In the first example, the laser 116 projects a laser beam 124 horizontally onto the side of the bath 100 towards a prism 122. The prism 122 redirects the light 90 degrees downward towards a photosensor 114 located below the bath 100. As the laser beam 124 travels through the bath solution 102, the light from the laser beam 124 is scattered by the bubbles 110, reducing the intensity of the laser beam 124. This reduction in the intensity of the laser beam 124 can be correlated with bubble characteristics such as bubble density, bubble uniformity, and bubble generation rate. Alternatively, the laser 116 may be located above or below the bath, and the photosensor 114 may be located on the side of the bath 100.

[0034] In the second example, the laser 116 projects a laser beam 124 perpendicularly from below the bath 100 toward a first prism 121 inside the bath 100. The first prism 121 redirects the laser beam 124 horizontally by 90 degrees toward a second prism 123. The second prism 123 redirects the laser beam 124 downward by 90 degrees toward a photosensor 114 located below the bath 100. As the laser beam 124 travels through the bath solution 102, the light from the laser beam 124 is scattered by the bubbles 110, reducing the intensity of the laser beam. This intensity can be converted into bubble characteristics such as bubble uniformity, bubble density, and bubble generation rate. Alternatively, the laser 116 and photosensor 114 can be positioned toward the bath 100 by changing the positions of the first prism 121 and the second prism 123.

[0035] Figure 7 is a cross-sectional view of the length of the surface preparation bath 100 filled with bath solution 102.

[0036] The wafers 104, supported by the wafer loading arm 106, are oriented vertically and positioned horizontally spaced above the gas injector 108. The bubbles 110 are emitted from orifices 109, which are spaced along the length of the gas injector 108. In this configuration, multiple light sources 112 are positioned below the bath 100 and spaced along the length of the bath 100. Multiple light sensors 114 are also positioned below the bath 100 and along the length of the bath 100. If desired, each of the multiple light sensors 114 may be configured to sense light from each of the multiple light sources 112.

[0037] Figure 8 shows an embodiment in which a gas injector in a bath 100 tank includes a light source 112. As shown in Figure 8, or in further embodiments, the gas injector 108 comprises the light source 112. In one embodiment, multiple LEDs or lasers may be integrated within the gas injector 108. In this arrangement, the light source 112 is attached to the inner surface of the bottom of the gas injector 108, for example, made of quartz. In alternative embodiments, other arrangements are possible. For example, the light source 112 may be located at other locations within the gas injector 108, or it may be located outside the gas injector 108 and protected from the bath solution 102 within the integrated gas injector 108 / light source 112 module.

[0038] Figure 9 shows one embodiment in which the bath tool is illuminated by a single light source.

[0039] Referring to Figure 9, one light source 112 is configured to illuminate multiple zones within the bath 100. A light beam 125, which may be a laser beam, is projected into an optical pipe 107 made of a transparent material such as Pyrex® or quartz. There are reflective surfaces 140 spaced along the inside of the optical pipe 107 that redirect multiple portions 142 of the light beam 125 into multiple zones of the bath 100. The optical pipe 107 may be designed to be located inside the bath 100, while the light source 112 may be located outside the bath 100.

[0040] Figure 10 shows an embodiment in which the bath tool is illuminated by a light source positioned around the light sensor.

[0041] Referring to Figure 10, a donut-shaped light source 146 illuminates the bath 100. In one embodiment, the donut-shaped light source 146 is formed like a ring. The donut-shaped light source 146 can be positioned either above or below the bath 100. The bath 100 can be uniformly illuminated when the donut-shaped light source 146 is positioned around a light sensor 114, which may be located at the center of the donut-shaped light source 146.

[0042] An example arrangement of the light sensor 114 is shown in Figures 11 and 12.

[0043] Figure 11 shows a top view of an array 150 of pixels 152, such as charge-coupled device (CCD) pixels, CMOS sensor pixels, or photodiode pixels. Such a pixel array 150 may be found within a CCD camera, CMOS sensor camera, or photodiode camera. These arrangements of optical sensors 114 can be used to capture a two-dimensional image of the bath 100. By analyzing pixels 152 from two different locations in the image, the uniformity in two different zones within the bath 100 can be compared.

[0044] Figure 12 shows a side view of an optical sensor 114 having a rectangular strip 154 ​​of pixels 152. This type of optical sensor 114 may be positioned adjacent to the bath 100 to capture light along the length of a gas injector 108. This arrangement may be used to monitor the velocity of bubbles 110 released from orifices 109 along the gas injector 108 and to determine whether any of the orifices 109 have expanded or become clogged. The rectangular strip 154 ​​of pixels 152 may consist of elements of a charge-coupled device (CCD) image sensor, a photodiode image sensor, or a CMOS array sensor.

[0045] Figure 13 shows an arrangement in which the light sources 112 are uniformly distributed across the bottom surface of the bath 100, and the light sensors 114 are arranged along the length and width of the sides of the bath 100. Different numbers of light sources 112 and light sensors 114 can be used than those shown.

[0046] The light source 112 may be an LED or a laser. The LED or laser may all be the same color or different colors. The light source 112 may be continuous or may flash on and off in a duty cycle synchronized with the light sensor 114. Data from the light sensor 114 may be communicated to the processor 180 by executing a program in the processor 180, as is known to those skilled in the art, and converted into information about bath conditions such as mixing and uniformity. The processor 180 may adjust the gas injection rate to increase or decrease mixing. The processor 180 may adjust the gas injection from individual gas injectors 108 to improve mixing uniformity. Alternatively, the processor 180 may adjust the power to the heating elements 107 to increase or decrease mixing, and may also locally adjust the power to individual heating elements 107 to improve mixing uniformity. The processor 180 may adjust the flow of components in the exothermic reaction to control the temperature of the bath 100, and therefore boiling. The processor 180 can also adjust the rate at which the bath solution 102 is injected into the bath through the fluid injector 103.

[0047] A system and method for controlling process variables and determining the endpoint of the surface preparation process in the bath 100 are shown in Figure 14.

[0048] The electromagnetic radiation sensor 115 captures electromagnetic radiation 176 emitted from the bath 100 (electromagnetic radiation such as long-wavelength infrared radiation for measuring temperature, visible light for measuring characteristics such as color, transparency, and turbidity, and short-wavelength infrared (IR) radiation from which the concentrations of various components in the fluid mixture can be determined from the intensity of the IR absorption peaks in the infrared (IR) spectrum of the fluid mixture).

[0049] Data from electromagnetic radiation sensors 115, such as a CCD sensor, photodiode sensor, or microbolometer, can be transmitted to a processor 180. The processor 180 can analyze the data and compare it to a first endpoint specification 184 and a second endpoint specification 186 stored in a non-volatile memory 182. If the sensor data matches the first endpoint specification 184, the processor can adjust the process or terminate the process. For example, if the surface preparation process is resist stripping, when the electromagnetic radiation sensor 115 no longer detects resist molecules in the stripping solution, the wafer 104 can be removed from the stripping bath and transferred to the rinsing bath. If the wet batch process is thin film etching, when the bath temperature or bath color indicates that etching is complete, the processor can terminate the etching process and begin transferring the wafer 104 to the rinsing tank. If the process is the preparation of an etching solution, the processor 180 can compare the bath temperature to a first endpoint specification 184 if the mixing is exothermic, or compare the concentration of components in the etching solution determined from the IR spectrum to a second endpoint specification 186. Once the endpoint specification is met, the processor 180 can then terminate the solution preparation step and begin lowering the wafer 104 into the bath 100.

[0050] The processor 180 can also analyze the data and compare it with the process variable target specifications stored in the non-volatile memory 182. The processor can then make adjustments to the surface preparation process to maintain the process variables at the target. For example, during the silicon nitride stripping process, the processor 180 can add water as needed to the high-temperature phosphoric acid / water mixture to maintain the boiling temperature at the target.

[0051] The electromagnetic radiation sensor 115 used for endpoint determination may be a short-wavelength infrared (IR) detector including a spectrometer. The spectrometer can sweep across a wavelength range and measure the intensity of IR light at each wavelength. The concentration of organic molecules in the solution can be determined from the intensity of the absorption peak in its characteristic IR spectrum. The IR spectrum of the fluid mixture can be compared with a first endpoint specification 184 and a second endpoint specification 186 stored in the non-volatile memory 182 to determine whether the current surface preparation step should be adjusted or terminated.

[0052] Figures 15B and 16B schematically show the IR spectra of ethanol and water, respectively. Figures 15A and 16A show ethanol molecules and water molecules. The unit of wavelength used in IR spectroscopy is inverse centimeter (cm). -1 This is the reciprocal of the wavelength in units of 0, or the wavenumber. In Figure 15B, the wavenumber ranges from 4000 to 900 cm along the x-axis. -1 The percentage transmittance of IR light when swept to the y-axis is recorded. 3391 cm² is shown in trough 210. -1 In this case, the OH bond in ethanol elongates and absorbs IR energy, so the IR transmittance decreases to about 40%. The 1055 cm² shown in trough 212 -1 In this case, the CO bond in ethanol extends and absorbs IR energy, so the IR transmittance decreases to approximately 45%. The percentage transmittance at these wavenumbers depends on the ethanol concentration in the mixture.

[0053] Figure 16B shows the IR spectrum of water. The IR spectrum is 3266 cm⁻¹, indicated by trough 224. -1 In this region, the OH bonds in water extend and absorb IR energy, reducing the IR transmittance to approximately 45%. The 1634 cm² shown in trough 226 is significant. -1 In this case, the scissor motion of OH bonds in water absorbs IR energy, so the IR transmittance is reduced to about 70%.

[0054] The spectrum of the fluid mixture within bath 100 can be obtained by scanning the wavelength with electromagnetic radiation sensor 115 using a spectrometer. Processor 180 can then compare the IR spectrum of the fluid mixture to a second endpoint specification 186 of a reference, which can be a spectrum, stored in memory 182, and initiate a change to the process if the spectra match. For example, when a fluid mixture of ethanol 200 and water 220 is prepared, the spectrum of the fluid mixture can be repeatedly obtained and compared to the second endpoint specification 186 of the reference stored in memory 182. When the IR spectrum of the mixture matches the second endpoint specification 186 of the reference, the desired ratio of ethanol to water is achieved. The ratio of ethanol to water can also be monitored throughout the process, and processor 180 can recommend adding water or ethanol as needed to maintain the composition at the target.

[0055] FIG. 17 shows an alternative apparatus and method for determining the concentration of components within bath solution 102 using a short wavelength IR spectrum. Instead of using a spectrometer, an IR source 190 having wavelengths at absorption peaks that uniquely identify the fluid components can be projected through the bath solution 102 mixture and captured by electromagnetic radiation sensor 115 sensitive to these wavelengths. A filter can be added to enable independent measurements of the transmittance at two wavelengths. Alternatively, IR source 190 can be flashed on and off in synchronization with electromagnetic radiation sensor 115 to independently measure the transmittance at different wavelengths. This apparatus and method are less costly than a spectrometer.

[0056] For example, in a mixture containing ethanol 200 and water 220, the broad absorption peak (trough) 210 of ethanol at 3391 cm -1 interferes with the broad absorption peak (trough) 224 of water at 3266 cm -1 and thus cannot be used. In an ethanol / water mixture, the absorption peak (trough) 212 at 1055 cm -1 is unique to ethanol, and at 1634 cm-1 The absorption peak (trough) 226 at is specific to water. The intensity of the transmitted radiation from the two IR sources 190 having these two wavelengths is captured by the electromagnetic radiation sensor 115 and can be compared by the processor 180 to a reference first endpoint intensity 194 and a reference second endpoint intensity 196 stored in memory 182. When the data from the electromagnetic radiation sensor 115 matches the reference first endpoint intensity 194, the desired ratio of ethanol to water has been achieved. This example is for illustrative purposes only. Other fluid mixtures containing components with specific infrared absorption peaks at other wavelengths can be used in a similar manner.

[0057] Herein, exemplary embodiments of the present invention are summarized. Other embodiments may also be understood from the entirety of this specification and the claims filed herein. Reference numerals are added below for illustrative purposes only, and various examples may be implemented in different ways and should not be construed as being limited to these examples alone.

[0058] Example 1. A method for processing multiple substrates includes immersing multiple substrates in a bath solution (102) contained in a bath (100), generating bubbles (110) in the bath solution (102), projecting light from a light source (112) toward the bath, generating optical sensor data by capturing the light emitted from the bath after interaction with the bubbles (110) using an optical sensor (114), and converting the optical sensor data into a metric of the bath solution.

[0059] Example 2. The method according to Example 1, wherein generating bubbles (110) includes injecting bubbles (110) through a gas injector (108) or boiling the bath solution.

[0060] Example 3. The method according to Example 1 or 2, wherein the metrics of the bath solution include static bubble size and count density, dynamic bubble size and count density, static bubble uniformity, dynamic bubble uniformity, bath solution uniformity, or bubble generation rate.

[0061] Example 4. The method according to any one of Examples 1 to 3, wherein projecting light from a light source (112) toward a bathtub illuminates multiple zones of the bath solution with multiple light sources spaced apart across the outer dimensions of the bathtub; generating photosensor (114) data by capturing light emitted from bubbles (110) includes capturing light emitted from a first zone of the multiple zones with a first photosensor (114A) of the photosensor (114) and capturing light emitted from a second zone of the multiple zones with a second photosensor (114B) of the photosensor (114); and converting the photosensor data into a metric of the bath solution includes comparing the bubble characteristics in the first zone with the bubble characteristics in the second zone based on the photosensor data.

[0062] Example 5. The method according to any one of Examples 1 to 4, wherein the outer dimensions of the bathtub are parallel to the main surfaces of the multiple substrates, the first zone includes a first portion of the main surfaces of the multiple substrates, and the second zone includes a second portion of the main surfaces of the multiple substrates.

[0063] Example 6. The method according to any one of Examples 1 to 4, wherein the outer dimensions of the bathtub are perpendicular to the main surfaces of the multiple substrates, the first zone includes a first portion of a gas injector (108) having a first orifice, and the second zone includes a second portion of a gas injector (108) having a second orifice.

[0064] Example 7. The method according to any one of Examples 1 to 6, wherein illuminating multiple zones of a bath solution with multiple light sources includes illuminating the first zone with first light of a first wavelength and illuminating the second zone with second light of a second wavelength, wherein the second wavelength is different from the first wavelength, and capturing the light further includes using a first filter to capture the light of the first wavelength and using a second filter to capture the light of the second wavelength.

[0065] Example 8. The method according to any one of Examples 1 to 6, wherein the method includes a plurality of light sources configured to periodically turn on and off in a duty cycle, and illuminating a plurality of zones, including flashing a first zone at a first frequency synchronized with a first light sensor and flashing a second zone at a second frequency synchronized with a second light sensor.

[0066] Example 9. The method according to any one of Examples 1 to 6, wherein projecting light from a light source (112) toward a bathtub forms a plane of laser (116) light above the surface of the bath solution, and generating photosensor data further comprises capturing light emitted from droplets produced by bursting bubbles (110) on the surface of the bath solution, and the metric of the bath solution includes bubble bursting uniformity across the surface of the bath solution, or the bubble bursting rate on the surface of the bath solution.

[0067] Example 10. The method according to any one of Examples 1 to 6, 9, wherein projecting light from a light source toward a bathtub includes redirecting the light with a prism bar (122).

[0068] Example 11. The bath treatment tool (10) includes a bathtub equipped with a loading arm and configured to hold a bath solution (102), a light source (112) mounted on a light source mounting assembly to project light toward the bathtub, and a light sensor (114) mounted on a sensor mounting assembly (30) to capture light emitted from the bathtub after interaction with bubbles (110) generated in the bath solution (102).

[0069] Example 12. The bath treatment tool according to Example 11, further comprising a gas injector (108) having an orifice (109) for releasing bubbles (110) located below the loading arm, or a heating element (107) for causing the bath solution to boil, or an inlet (103 / 108) for the flow of reactants into the bath solution, which is configurable to cause the bath solution to boil.

[0070] Example 13. A bath treatment tool according to Example 11 or 12, wherein the light source (112) includes a quartz gas injector having an integrated light-emitting diode (LED), a quartz gas injector rod configured to redirect light into multiple zones of a bath, a quartz loader arm having an integrated LED, a quartz loader arm configured to redirect light into multiple zones of a bath, or a ring illuminator surrounding a light sensor.

[0071] Example 14. A bath treatment tool according to any one of Examples 11 to 13, wherein the light source (112) includes multiple light sources spaced apart across the dimensions of the bathtub to illuminate different zones of the bath solution, and the light sensor (114) includes multiple light sensors configured to sense light from the multiple light sources.

[0072] Example 15. A bath treatment tool according to any one of Examples 11 to 14, wherein the light source (112) includes a plurality of light sources having different wavelengths.

[0073] Example 16. A bath treatment tool according to any one of Examples 11 to 13, wherein the light source (112) includes a laser (116) configured to generate a plane of laser light above the surface of the bath solution in the bathtub, and the photosensor (114) includes a charge-coupled device (CCD) image sensor or CMOS array sensor positioned above the plane of laser light and configured to capture light emitted from bubbles bursting on the surface of the bath solution.

[0074] Example 17. A bath treatment tool according to any one of Examples 11 to 13, comprising a first prism bar configured to redirect light toward a light sensor, or toward a second prism bar configured to redirect light toward a light sensor.

[0075] Example 18. The bath processing tool includes a bath for wet processing of a wafer (104), an electromagnetic radiation sensor for capturing electromagnetic signals from the bath solution in the bath, a processor (180), and a non-temporary memory (182) coupled to the processor (180) for storing a program, the non-temporary memory including instructions for the program to be executed in the processor, to determine the metric of the bath solution based on the electromagnetic signals, and to identify that the target specification for processing the wafer has been reached based on the metric of the bath solution.

[0076] Example 19. The bath treatment tool according to Example 18, wherein the metric is an endpoint metric and the processor is configured to terminate the process.

[0077] Example 20. A bath treatment tool according to Example 18 or 19, wherein the metric is a process target specification, and the processor is configured to adjust the flow of gas, the power to the heating element, or the flow of bath solution components in order to maintain the bath in the process target specification.

[0078] Example 21. A bath treatment tool according to any one of Examples 18-20, wherein the electromagnetic radiation sensor includes a long-wavelength infrared camera or a visible light camera, and the command for determining the endpoint metric of the bath solution further includes a command for determining the temperature of the bath solution with the long-wavelength infrared camera or the color of the bath solution with the visible light camera.

[0079] Example 22. A bath treatment tool according to any one of Examples 18 to 20, wherein the electromagnetic radiation sensor includes a short-wavelength camera or a short-wavelength camera having a variable wavelength filter, and the command for determining the endpoint metric of the bath solution further includes a command for determining the concentration of components in the bath solution with the short-wavelength camera or for determining the spectrum of components in the bath solution with the short-wavelength camera having a variable wavelength filter.

[0080] Example 23. A bath treatment tool described in any one of Examples 18 to 22 is an electromagnetic radiation source configured to generate an electromagnetic signal, further comprising a plurality of electromagnetic radiation sources having different short infrared wavelengths, each of which is configured to project short infrared wavelengths through a bath solution, an electromagnetic radiation sensor configured to capture the short infrared wavelengths transmitted through the bath solution, and the endpoint metric of the bath solution comprising the spectrum of components in the bath solution.

[0081] Example 24. An endpoint detection method comprising: processing a wafer in a wet process; capturing an electromagnetic signal (176) from a bath solution (102) in a bath during processing using an electromagnetic radiation sensor (115); determining the endpoint metric of the bath solution based on the electromagnetic signal; and stopping the wet process in response to identifying that the endpoint of processing has been reached based on the endpoint metric of the bath solution.

[0082] Example 25. The method according to Example 24, wherein determining the endpoint metric of the bath solution includes determining the temperature of the bath solution with a long-wavelength infrared camera, determining the color of the bath solution with a visible light camera, determining the concentration of components in the bath solution with a short-wavelength camera, or determining the spectrum of components in the bath solution with a short-wavelength camera having a variable wavelength filter.

[0083] Example 26. A process control method comprising: processing a wafer in a wet process; capturing an electromagnetic signal (176) from a bath solution (102) in a bath during processing using an electromagnetic radiation sensor (115); determining the process target specifications of the bath solution based on the electromagnetic signal; and adjusting the bath solution according to the determination of the process target specifications based on the process target specifications of the bath solution.

[0084] Example 27. The method according to Example 26, wherein adjusting the bath solution includes adjusting the flow of gas, adjusting the power to the heating element (107), or adjusting the flow of bath solution components to maintain the bath to process target specifications.

[0085] While the present invention has been described with reference to exemplary embodiments, this specification is not intended to be constrained. Those skilled in the art will find various modifications and combinations of those exemplary embodiments, as well as other embodiments of the present invention, readily apparent by reference to this specification. Accordingly, the appended claims are intended to encompass all such modifications or embodiments.

Claims

1. A method for processing multiple substrates, The steps include immersing the plurality of substrates in the bath solution contained in the bathtub, The steps include generating bubbles in the bath solution, A step of projecting light from multiple light sources toward the bathtub, wherein each of the multiple precursor substrates extends across multiple zones, and the multiple zones are illuminated by two or more of the multiple light sources, The steps include generating optical sensor data by capturing light emitted from the bathtub using an optical sensor after interaction with the bubbles, A step of converting the optical sensor data into a metric of the bath solution, comprising the step of generating zone comparison data across a wafer based on comparing light emitted from one of the plurality of zones with light emitted from another of the plurality of zones, A method having

2. The method according to claim 1, wherein the step of generating bubbles comprises the step of injecting the bubbles through a gas injector, or the step of boiling the bath solution.

3. The method according to claim 1, wherein the metric of the bath solution includes static bubble size and count density, dynamic bubble size and count density, static bubble uniformity, dynamic bubble uniformity, bath solution uniformity, or bubble generation rate.

4. The step of projecting the light from the plurality of light sources toward the bathtub comprises the step of irradiating the plurality of zones of the bath solution with a plurality of light sources spaced apart over the outer dimensions of the bathtub, The step of generating optical sensor data by capturing the light emitted from the aforementioned bubble is: The first light sensor of the aforementioned light sensor captures light emitted from the first zone of the plurality of zones, The steps include capturing light emitted from the second zone of the plurality of zones using the second light sensor of the aforementioned light sensor, It has, The method according to claim 1, wherein the step of converting the optical sensor data into the metric of the bath solution comprises the step of comparing the bubble characteristics in the first zone with the bubble characteristics in the second zone based on the optical sensor data.

5. The outer dimensions of the bathtub are parallel to the main surfaces of the plurality of substrates. The first zone includes a first portion of the main surface of the plurality of substrates, The method according to claim 4, wherein the second zone includes a second portion of the main surface of the plurality of substrates.

6. The outer dimensions of the bathtub are perpendicular to the main surfaces of the plurality of substrates. The first zone includes a first portion of a gas injector having a first orifice, The method according to claim 4, wherein the second zone includes a second portion of the gas injector having a second orifice.

7. The step of irradiating multiple zones of the bath solution with multiple light sources comprises the steps of irradiating the first zone with first light of a first wavelength and irradiating the second zone with second light of a second wavelength. The second wavelength is different from the first wavelength, The light-capturing step is further, A step of capturing light of the first wavelength using a first filter, A step of capturing light of the second wavelength using a second filter, The method according to claim 4, having the following characteristics.

8. The plurality of light sources have illumination configured to be periodically turned on and off in a duty cycle, The step of irradiating the aforementioned multiple zones is: A step of flashing the first zone at a first frequency synchronized with the first light sensor, A step of flashing the second zone at a second frequency synchronized with the second light sensor, The method according to claim 4, having the following characteristics.

9. The step of projecting the light from the plurality of light sources toward the bathtub includes the step of forming a plane of laser light above the surface of the bath solution, The step of generating optical sensor data further includes capturing light emitted from droplets formed by the bursting of bubbles on the surface of the bath solution, The method according to claim 1, wherein the metric of the bath solution has the uniformity of bubble bursting across the surface of the bath solution, or the rate of bubble bursting on the surface of the bath solution.

10. The method according to claim 1, wherein the step of projecting the light from the plurality of light sources toward the bathtub includes the step of changing the direction of the light with a prism bar.

11. The method according to claim 1, wherein the step of capturing light emitted from the bathtub comprises scanning the light sensor along the diameter of the plurality of substrates.

12. The step of generating the bubbles includes injecting the bubbles through a plurality of gas injectors oriented along a first direction, Each of the plurality of gas injectors has a plurality of orifices having openings oriented along a second direction perpendicular to the first direction, The method according to claim 1, wherein the light beams from the plurality of light sources are guided along the second direction.

13. A method for processing multiple substrates, A step of immersing the plurality of substrates in a bath solution contained in a bathtub, wherein the bathtub has wafer loading arms extending along a first direction, A step of holding the plurality of substrates in the bath solution with the wafer loading arm, wherein adjacent substrates of the plurality of substrates are held along the first direction, and each of the plurality of substrates has a diameter along a second direction perpendicular to the first direction, A step of generating bubbles in the bath solution from a plurality of gas injectors oriented along the first direction, A step of projecting light from multiple light sources toward a plurality of substrates, wherein the plurality of light sources include a first light source that emits light at a first wavelength toward a first zone and a second light source that emits light at a second wavelength toward a second zone, wherein the second wavelength is different from the first wavelength, the first zone and the second zone are different locations in the bath solution along the first direction, each of the plurality of gas injectors has a plurality of orifices having apertures directed toward a third direction perpendicular to the first and second directions, and the light beams from the plurality of light sources are guided toward the third direction, A light sensor comprising the step of generating light sensor data based on the step of capturing light emitted from bubbles in the bath solution, wherein the step of capturing light further comprises the steps of capturing light of a first wavelength from a first zone using a first light sensor and a first filter, and capturing light of a second wavelength from a second zone using a second light sensor and a second filter, The steps include converting the optical sensor data into a metric of the bath solution, A method having

14. The method according to claim 13, wherein the metric of the bath solution includes static bubble size and count density, dynamic bubble size and count density, static bubble uniformity, dynamic bubble uniformity, bath solution uniformity, or bubble generation rate.

15. A method for processing multiple substrates, A step of immersing the plurality of substrates in a bath solution contained in a bathtub, wherein the bathtub has wafer loading arms extending along a first direction, A step of holding the plurality of substrates in the bath solution with the wafer loading arm, wherein adjacent substrates of the plurality of substrates are held along the first direction, and each of the plurality of substrates has a diameter along a second direction perpendicular to the first direction, A step of generating bubbles in the bath solution from a plurality of gas injectors oriented along the first direction, A step of projecting light from multiple light sources toward the multiple substrates, wherein the multiple light sources include a first light source that emits light at a first wavelength toward a first zone and a second light source that emits light at a second wavelength toward a second zone, wherein the second wavelength is different from the first wavelength, and the first zone and the second zone are different positions in the bath solution along the first direction, A light sensor comprising the step of generating light sensor data based on the step of capturing light emitted from bubbles in the bath solution, wherein the step of capturing light further comprises the steps of capturing light of a first wavelength from a first zone using a first light sensor and a first filter, and capturing light of a second wavelength from a second zone using a second light sensor and a second filter, The steps include converting the optical sensor data into a metric of the bath solution, It has, A method wherein the plurality of light sources are arranged in the plurality of gas injectors, and the step of projecting light from the plurality of light sources includes the step of projecting light of a different wavelength from each of the plurality of gas injectors.

16. The plurality of light sources have illumination configured to be periodically turned on and off in a duty cycle, The step of projecting light from the aforementioned multiple light sources is: A step of flashing the first zone at a first frequency synchronized with the first light sensor, A step of flashing the second zone at a second frequency synchronized with the second light sensor, The method according to claim 13, having the following characteristics.

17. The method according to claim 15, wherein the metric of the bath solution includes static bubble size and count density, dynamic bubble size and count density, static bubble uniformity, dynamic bubble uniformity, bath solution uniformity, or bubble generation rate.

18. The plurality of light sources have illumination configured to be periodically turned on and off in a duty cycle, The step of projecting light from the aforementioned multiple light sources is: A step of flashing the first zone at a first frequency synchronized with the first light sensor, A step of flashing the second zone at a second frequency synchronized with the second light sensor, The method according to claim 15, having the following characteristics.

19. Each of the plurality of gas injectors has a plurality of orifices having openings oriented along a third direction perpendicular to the first and second directions, The method according to claim 15, wherein the light beams from the plurality of light sources are guided along the third direction.

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