Optical Sensor for Remote Temperature Measurement

Abstract

Aspects of the present disclosure provide a sensor for remote temperature measurement. For example, the sensor may include a light source configured to form an irradiation beam, a focusing optical system configured to direct the irradiation beam from the light source to an irradiation spot on a semiconductor sample to excite bandgap photoluminescence (PL) light in the semiconductor sample, a condensing optical system configured to condense the bandgap PL light excited from the semiconductor sample, at least one optical detector configured to measure the spectral intensity of the bandgap PL light in the vicinity of the semiconductor bandgap wavelength of the semiconductor sample, and a transmission optical system configured to transmit the bandgap PL light from the condensing optical system to the at least one optical detector.

Description

Technical Field

[0001] Cross - Reference to Related Applications This disclosure claims the benefit of U.S. Provisional Patent Application No. 63 / 347,713, filed on June 1, 2022, entitled "OPTICAL SENSOR FOR REMOTE TEMPERATURE MEASUREMENTS", which is hereby incorporated by reference in its entirety.

[0002] This disclosure generally relates to temperature measurement, and more specifically, to an optical sensor for remote temperature measurement in a semiconductor wafer wet manufacturing process.

Background Art

[0003] The background description provided herein is for the purpose of generally presenting the background of the disclosure. Aspects of the research of the inventors of the present application and descriptions that would not otherwise be recognized as prior art at the time of filing in the scope described in this background section are not admitted as prior art to the present disclosure, either explicitly or implicitly.

[0004] The semiconductor wafer wet manufacturing process may require a remote sensor to detect the temperature of a wafer in a container filled with a processing liquid, where both the container wall and the processing liquid may not be transparent to mid - infrared wavelengths. This lack of transparency makes it impossible to use conventional radiation temperature sensors.

[0005] The wet etching process is an example, in which a batch of wafers is placed in a quartz tank filled with a processing liquid containing phosphoric acid (H3PO4), water, and similar chemicals. A plurality of quartz tanks are separated by regions filled with the processing liquid, and one quartz tank can be nested within another. Temperature sensing of the wafers must be performed along an optical path that crosses the quartz wall and passes through a region filled with the processing liquid that may contain bubbles. Bubbles present in the processing liquid can cause problems such as signal fluctuations, for example due to movement within the liquid. Statistical window filters may also be employed to remove signal fluctuations, noise, and other anomalies. In process control, it can be important to accurately measure the temperature of the wafers within the quartz tank, preferably at multiple points across the wafer so that the uniformity of the wet etching process can be inferred from the wafer temperature distribution.

[0006] When the temperature range of the wafer is from 100 to 170 °C, the corresponding peak of blackbody radiation is in the wavelength range of 6 to 8 μm, i.e., in the mid-infrared region, but quartz transmits only infrared (IR) radiation with wavelengths less than about 4 μm. The IR transmittance of water and H3PO4 is very low at wavelengths greater than about 1.7 μm.

[0007] There is clearly a need for a sensor that can measure the temperature of a wafer under such difficult optical access conditions by utilizing a portion of the optical spectrum that is not affected by IR transmission losses, i.e., an optical spectrum that is mainly in the near-infrared (NIR). SUMMARY OF THE INVENTION

[0008] Disclosed is the concept of a remote temperature sensor that can measure the temperature of a wafer or other object containing silicon (Si) or other semiconductor materials, which is placed in a container made of quartz or a similar material and immersed in a liquid that is opaque to mid-infrared. The disclosed method does not rely on thermal radiation from the wafer itself.

[0009] This concept is based on the physical effect of the inter-band absorption measurement of a semiconductor from photoluminescence (PL). This effect depends on the temperature dependence of the distribution of electrons in the valence band and conduction band of the semiconductor. When the temperature is high, electrons generally occupy higher energy levels. Information about the distribution of electrons at the energy levels can be obtained by irradiating the sample with photons of a known wavelength and analyzing the acquired spectrum of the PL photons emitted by the irradiated sample. The temperature of the sample can be determined from the characteristics of the PL spectrum, such as the spectral peak wavelength and spectral intensity distribution.

[0010] In a preferred embodiment, a near-infrared (NIR) light source with a focusing optical system forms an irradiation spot on a sample made of a semiconductor material. A condensing optical system is used to collect the band-gap PL light emitted by the sample at the irradiation spot and transmit it to an optical detector such as a spectrometer or other suitable detector that enables spectral analysis in the band-gap wavelength region, which is typically about 1100 nm in silicon (Si). The spectral intensity distribution of the band-gap PL light can be used to determine the temperature of the sample using appropriate calibration.

[0011] Aspects of the present disclosure provide a sensor for remote temperature measurement. For example, the sensor may include a light source configured to form an irradiation beam, a focusing optical system configured to direct the irradiation beam from the light source to an irradiation spot on a semiconductor sample to excite band-gap photoluminescence (PL) light in the semiconductor sample, a condensing optical system configured to collect the band-gap PL light excited from the semiconductor sample, at least one optical detector configured to measure the spectral intensity of the band-gap PL light in the vicinity of the semiconductor band-gap wavelength of the semiconductor sample, and a transmission optical system configured to transmit the band-gap PL light from the condensing optical system to the at least one optical detector.

[0012] In one embodiment, the transmission optical system may include a notch filter configured to suppress the transmission of light at the wavelength of the irradiation beam. In another embodiment, the transmission optical system may include at least one of a dichroic mirror, a beam splitter, and an optical fiber.

[0013] In one embodiment, the focusing optical system and the condensing optical system may utilize the same lens to focus the irradiation beam onto the semiconductor sample and to condense the bandgap PL light from the semiconductor sample, respectively. In another embodiment, the light source may include a near-infrared (NIR) laser diode or a light-emitting diode (LED). In some embodiments, the irradiation beam may have a wavelength of 785 nm.

[0014] In one embodiment, at least one optical detector may include a prism spectrometer or a grating spectrometer. In some embodiments, at least one optical detector may include at least two single-pixel detectors, each of the at least two single-pixel detectors may have an optical bandpass filter disposed in front of it, and each of the optical bandpass filters may be configured to transmit a wavelength or a range of wavelengths in the vicinity of the semiconductor bandgap wavelength of the semiconductor sample. For example, the single-pixel detector may be a photodiode. In another example, the photodiode may be a silicon (Si) photodiode, a germanium (Ge) photodiode, or an InGaA photodiode. In one embodiment, the optical bandpass filters of the at least two single-pixel detectors may each have passband wavelengths of 1050 nm and 1125 nm.

[0015] In one embodiment, the semiconductor sample can be a semiconductor wafer disposed within a wet processing tank, and the focusing optical system and the condensing optical system can be configured to direct an irradiation beam onto the semiconductor wafer through one or more walls of the wet processing tank and also through the processing liquid present in the wet processing tank, and to collect the bandgap PL light from the semiconductor wafer. For example, the one or more walls can be nested and can include quartz. As another example, the processing liquid can include at least one of H3PO4, H2O, H2O2, and H2SO4.

[0016] In one embodiment, the sensor can further include a controller configured to obtain the PL spectral light intensity from at least one optical detector and determine the temperature of the semiconductor sample from the obtained PL spectral light intensity.

[0017] Aspects of the present disclosure also disclose a temperature measuring device. For example, the temperature measuring device can include a base plate. The temperature measuring device can further include a plurality of the above-described sensors attached to and disposed across the base plate, the sensors being configured to measure the temperature of one or more semiconductor samples.

[0018] In one embodiment, the base plate can be disposed substantially parallel to one of the one or more semiconductor samples, and the sensor can be configured to determine the temperature distribution across the surface of one of the one or more semiconductor samples at a plurality of irradiation spots thereon corresponding to the sensor. In another embodiment, the base plate can be disposed substantially perpendicular to the one or more semiconductor samples, and the sensor can be configured to measure the temperature in at least one edge or a region proximate to an edge of one of the one or more semiconductor samples.

[0019] In one embodiment, the temperature measurement device may further include a temperature control system configured to control the temperature of the base plate and the sensor. For example, the temperature control system may include a temperature-controlled fluid manifold that contacts or is incorporated within the base plate. As another example, the temperature control system may include one or more thermoelectric (TE) devices that contact the base plate.

[0020] Aspects of the present disclosure also disclose a wet semiconductor processing system. For example, the wet semiconductor processing system may include a wet semiconductor processing tank. The wet semiconductor processing system may further include the temperature measurement device described above. In one embodiment, the temperature measurement device may be configured to measure the temperature of one or more semiconductor samples disposed within the wet semiconductor processing tank through one or more walls of the wet semiconductor processing tank and also through the processing liquid in the wet semiconductor processing tank.

[0021] Aspects of the present disclosure also disclose a remote temperature measurement method. For example, the method may include irradiating a semiconductor sample with an irradiation beam to excite bandgap photoluminescence (PL) light in the semiconductor sample. The method may also include measuring the spectral intensity of the excited bandgap PL light from the semiconductor sample and determining the temperature of the semiconductor sample based on the measured spectral intensity.

[0022] In one embodiment, measuring the spectral intensity of the bandgap PL light may include measuring the spectral intensity of the bandgap PL light at two wavelengths or two ranges of wavelengths in the vicinity of the semiconductor bandgap wavelength of the semiconductor sample.

[0023] Of course, the order of the descriptions of the various steps described in this specification is presented for ease of explanation. Generally, these steps can be executed in any appropriate order. Furthermore, although each of the various features, techniques, configurations, etc. described in this specification may be described in separate places of the present disclosure, each concept is to be construed as capable of being executed independently of one another or in combination with one another. Accordingly, the present disclosure can be implemented and contemplated in various manners.

[0024] Note that this summary section does not specify any embodiment or / and progressively novel aspect of the disclosure of the present disclosure or claims. Rather, this summary merely provides a preliminary discussion of corresponding points that are novel over various embodiments and conventional techniques. For further details and / or possible perspectives of the present disclosure and embodiments, the reader is referred to the detailed description section of the present disclosure and the corresponding drawings described further below.

Brief Description of the Drawings

[0025] Various embodiments of the present disclosure proposed by way of example will be described in detail below with reference to the following drawings. In the drawings, like numbers refer to like elements.

[0026]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

Figure 8

DETAILED DESCRIPTION

[0027] The following description is provided in connection with the use of a remote temperature sensor for measuring the temperature of a semiconductor sample (e.g., a semiconductor wafer) disposed within a wet semiconductor processing tank. It should be understood that the same methods, apparatus, and systems for this are applicable to other remote temperature measurements of objects exhibiting bandgap photoluminescence (PL) in various environments.

[0028] FIG. 1 is a schematic diagram of an exemplary wet semiconductor processing system 10 according to some embodiments of the present disclosure. The wet semiconductor processing system 10 may include a sensor 100 (e.g., a temperature sensor) used to detect the temperature of an object 110 (e.g., a semiconductor sample such as a semiconductor wafer (e.g., a silicon (Si) wafer)) in a wet semiconductor manufacturing process. In one embodiment, a film (e.g., a resist layer) may be formed on the wafer 110. In the wet semiconductor manufacturing process, the wafer 110 may be disposed in a wet semiconductor bath (or wet semiconductor processing bath) 111 filled with a processing liquid 112. In one embodiment, the wet processing bath 111 may include a plurality of containers (e.g., quartz containers) separated by a region filled with the processing liquid 112 and nested one quartz bath within another. In some embodiments, both the processing liquid 112 and the wall 113 (e.g., a quartz wall) of the wet processing bath 111 (or the plurality of containers) may not be transparent to mid-infrared wavelengths. In one embodiment, the processing liquid 112 may include at least one of water, H2O2, H2SO4, phosphoric acid (H3PO4), and similar chemicals.

[0029] The sensor 100 may include a light source 120 used to form an irradiation beam 121. In one embodiment, the light source 120 may be a near-infrared (NIR) light source such as a laser diode or a light-emitting diode (LED) operating at a wavelength of, for example, 785 nm, and may form an irradiation beam 121 that is IR light (or NIR light). Other light source wavelengths (e.g., visible light) may be used, and alternative embodiments may include narrow-band LEDs or broadband light sources with interference filters for selecting the wavelength range for wafer irradiation.

[0030] Optionally, the sensor 100 may further include an irradiation collimator 122. In one embodiment, as shown in FIG. 1, the irradiation collimator 122 may be incorporated within the light source 120. In another embodiment, the irradiation collimator 122 may be separated from the light source 120. The irradiation collimator 122 may be used to collimate the irradiation beam 121 formed by the light source 120.

[0031] In one embodiment, the sensor 100 may further include a focusing optical system 130. The focusing optical system 130 can be used to direct the collimated irradiation beam 121 onto the wafer surface 116 of the wafer 110 to form an irradiation spot 114 thereon. The collimated irradiation beam 121 can cross a plurality of regions filled with a plurality of quartz walls (if any) 113 and the processing liquid 112 before reaching the irradiation spot 114. On the wafer surface 116 (i.e., on the irradiation spot 114), the irradiation beam 121 optionally guided through a film formed on the wafer 110 can excite the wafer 110 to emit a photon beam (in this case, a photon beam called bandgap photoluminescence (PL) light (or PL light) 115). In one aspect, by the irradiation beam 121 penetrating the film formed on the substrate, it becomes possible to measure the temperature of the underlying wafer regardless of the film.

[0032] In one embodiment, the sensor 100 may further include a condensing optical system 132. In one embodiment, as shown in FIG. 1, the condensing optical system 132 may be integrated with the focusing optical system 130 and may include the same focusing lens. In another embodiment, the focusing optical system 130 and the condensing optical system 132 may be separated and may not be aligned along the same optical axis. The incident angle of the irradiation beam 121 and the angle of the axis of the excited and condensed PL light 115 may or may not have a direction perpendicular to the wafer surface 116. Preferably, the incident angle of the irradiation beam 121 has a non-perpendicular direction with respect to the wafer surface 116 so that the irradiation beam 121 of the excitation wavelength after reflection from the wafer surface 116 does not enter the condensing optical system 132 again, thereby reducing the risk of light pollution. The condensing optical system 132 is designed to condense the PL light 115 excited by the wafer 110 at the irradiation spot 114. In one embodiment, the PL light 115 generally has a Lambertian distribution, and the purpose of the condensing optical system 132 is to condense as much of the PL light 115 after crossing the quartz wall 113 and the processing liquid 112 as possible and deliver the condensed PL light 115 to the optical detector 170 with minimal loss.

[0033] In one embodiment, the sensor 100 may further include a detector focusing optical system (transmission optical system) 160. The detector focusing optical system 160 can guide and transmit the PL light 115 from the condensing optical system 132 to the optical detector 170. In the exemplary embodiment of FIG. 1, a dichroic mirror (DM) 140 is used to separate the NIR light of the irradiation beam 121 from the PL light 115 and guide the PL light 115 to the optical detector 170. In some embodiments, the detector focusing optical system 160 may further include a beam splitter and an optical fiber. In one embodiment, since the irradiation beam 121 can be of a very high intensity compared to the condensed PL light 115, a notch filter 150 having a "notch center" wavelength corresponding to the wavelength of the NIR light source 120 (e.g., 785 nm) can be used to further remove any scattered irradiation beam 121 in the optical detector path.

[0034] The optical detector 170 can acquire the spectrum (or spectral intensity) of the PL light 115 that can determine the temperature of the wafer 110 (at the position of the irradiation spot 114) and can be used for analysis. In one embodiment, the optical detector 170 can be a prism spectrometer or a grating spectrometer having detectors such as a CCD, a CMOS, a photodiode (PD) array, a position sensitive detector (PSD).

[0035] In one embodiment, the PL light 115 can be focused by the detector focusing optical system 160 at the end of an optical fiber (not shown) that transmits the PL light 115 to an optical detector (e.g., the optical detector 170) remotely disposed from the focusing optical system 130, the condensing optical system 132, and the wet processing tank 111. In some embodiments, the sensor 100 may further include another optical fiber disposed between the light source 120 and the focusing optical system 130 and configured to transmit the irradiation beam 121 from the NIR light source 120 to the focusing optical system 130.

[0036] According to the present disclosure, for temperature measurement with sufficient accuracy, it is not necessary to measure the entire PL spectrum with high wavelength resolution. To determine the temperature of the wafer 110 at the irradiation spot 114 sufficiently accurately, it is sufficient to measure at least two optical wavelengths in the vicinity of the bandgap wavelength of the PL light 115.

[0037] FIG. 2 shows the spectral distribution (or spectral intensity or spectrum) of the PL light (e.g., PL light 115) in silicon (Si) (e.g., silicon wafer 110) that has undergone a shift in the spectral peak due to temperature (e.g., 25° C. and 105° C.). The spectral distribution is plotted in the absence of the processing liquid (e.g., processing liquid 112), but when the processing liquid is present, the spectral distribution exhibits the same spectral characteristics although the signal level decreases. By measuring the spectral intensity of the PL light at wavelengths λ1 and λ2 in the vicinity of the 1100 nm bandgap wavelength of the PL light with a dual photodiode or similar sensor, it is possible to use the measured intensity with appropriate calibration to determine the temperature of the silicon wafer 110. For example, since the ratio of the spectral intensities at the two wavelengths changes with the temperature of the wafer 110, the ratio of the spectral intensities at the two wavelengths λ1 and λ2 may be associated with the temperature. Simpler or more complex metrics and calibrations including the measured spectral intensity may be utilized. In one embodiment, the two wavelengths λ1 and λ2 are selected within one or more high-sensitivity regions (e.g., regions R1 and R2) of the PL light spectrum where the ratio of the spectral intensities of the PL light 115 at the two wavelengths λ1 and λ2, and the difference between the spectral distributions of the PL light 115 measured at different temperatures are large.

[0038] To increase the accuracy further, more than three spectral intensities may be measured and used for calibration and temperature determination. In one embodiment, the term "vicinity" may indicate a distance of 1, 2, 3,..., 99, 100,..., 199, or 200 nm from the bandgap wavelength.

[0039] Figure 3 is a schematic diagram of an exemplary sensor 300 (e.g., a temperature sensor) according to some embodiments of the present disclosure. Sensor 300 is less expensive than sensor 100. Similar to sensor 100, sensor 300 may also include a light source 120, an optional illumination collimator 122 (shown in FIG. 1), a focusing optical system 130, and a light collecting optical system 132. In one embodiment, sensor 300 may further include at least two photodiodes instead of the optical detector 170. For example, sensor 300 may include a first photodiode PD1 and a second photodiode PD2, or a similar single pixel detector. In some embodiments, the first photodiode PD1 and / or the second photodiode PD2 may be a silicon (Si) photodiode, a germanium (Ge) photodiode, or an InGaA photodiode. In one embodiment, each of the first photodiode PD1 and the second photodiode PD2 may have a corresponding spectral bandpass filter disposed in the PL light path in front of the photodiode. For example, the first bandpass filter BF1 may be disposed in the first PL light path LP1 in front of the first photodiode PD1, and the second bandpass filter BF2 may be disposed in the second PL light path LP2 in front of the second photodiode PD2. In one embodiment, the first bandpass filter BF1 and the second bandpass filter BF2 may be selected to pass the PL light wavelengths of 1050 nm and 1125 nm (both wavelengths are in the vicinity of the 1100 nm bandgap wavelength of Si) to the first photodiode PD1 and the second photodiode PD2, respectively. In one embodiment, sensor 300 may further include a dichroic mirror (DM) 340, and the dichroic mirror (DM) 340 may be used to separate a portion of the PL light 115 and deflect it to its corresponding spectral bandpass filter and photodiode. In FIG. 3, the light source path is perpendicular to the plane of the drawing before being deflected towards the wafer. Also, as shown in FIG. 3, a notch filter (e.g., notch filter 150) may also be used to suppress the scattering of NIR light (e.g., the irradiation beam 121 (shown in FIG. 1)) to the first photodiode PD1 and the second photodiode PD2.

[0040] In one embodiment, the first photodiode PD1 and the second photodiode PD2 can be used to measure the spectral intensity of the PL light 115 in the wavelength ranges of 1050 nm and 1125 nm, and the signals generated by the first photodiode PD1 and the second photodiode PD2 can be supplied to processing electronics (not shown) for amplification, filtering, AD conversion, and further processing necessary for determining the temperature of the wafer. For example, the sensor 300 (or the sensor 100) is coupled to the first photodiode PD1 and the second photodiode PD2 (or the optical detector 170), and may further include a controller configured to obtain the PL spectral light intensity from the first photodiode PD1 and the second photodiode PD2 (or the optical detector 170) and determine the temperature of the wafer 110 from the obtained PL spectral light intensity. The sensor 300 includes a first bandpass filter BF1 and a second bandpass filter BF2 for filtering noise. For example, due to the presence of bubbles in the processing liquid (e.g., the processing liquid 112 shown in FIG. 1), a lot of noise may be included in the measured spectral intensity of the PL light 115.

[0041] Furthermore, when the level of the processing liquid 112 in the wet processing tank 111 (shown in FIG. 1) causes the irradiation beam 121 and the PL light 115 to change so as to cross an air or other gas environment because the free surface of the processing liquid 112 in the wet processing tank 111 is below the position of the sensor 100 / 300, different calibrations may be required to account for the different media (air vs. processing liquid) along the optical path, and the sensor (e.g., sensors 100 and 300), and the measurement system (e.g., the wet semiconductor processing system 10) need to be able to monitor the level of the processing liquid 112 and account for the media present during measurement.

[0042] Figures 4A and 4B show a sensor assembly (or wafer temperature measurement device) 400 of an exemplary single temperature sensor (e.g., sensor 100 or 300) according to some embodiments of the present disclosure. The light source 120, the first photodiode PD1 and the second photodiode PD2, the first bandpass filter BF1 and the second bandpass filter BF2, the focusing optical system 130, and the condensing optical system 132 (shown in FIGS. 1 and 3) of the sensor 300 can all be integrated into a metal housing (e.g., metal housing 490). In one embodiment, the metal housing 490 may have a high thermal conductivity to enable proper external cooling of the sensor assembly 400 to ensure the stability of the output of the light source 120 and the low noise level in the first photodiode PD1 and the second photodiode PD2. In one embodiment, due to sufficient cooling and temperature stabilization, inexpensive silicon (Si) photodiodes can be used for the first photodiode PD1 and the second photodiode PD2. In other embodiments, InGaAs photodiodes or germanium (Ge) photodiodes can be used for the first photodiode PD1 and the second photodiode PD2. Different from other optical measurement techniques, PL temperature measurement applications do not necessarily require a stabilized NIR light source. In one embodiment, the NIR light source 120 can be a laser diode with a power of 50 to 500 mW incorporating a monitoring / reference photodiode. With the above-described sensor configuration, in a quartz container (or tank) containing an SC1 / H3PO4 treatment solution, on a polysilicon wafer, a wafer temperature measurement sensitivity of less than 0.5 °C has been demonstrated in a state where the temperature range of the treatment solution (and the wafer) is 120 to 165 °C.

[0043] In an alternative embodiment, a spectrometer can be used for measuring the PL intensity in a spectral band selected by a screen having an opening disposed in front of an optical detector (e.g., optical detector 170), and these detectors can include single-pixel optical detectors such as photodiodes (e.g., the first photodiode PD1 and the second photodiode PD2).

[0044] In yet a further embodiment, a beam splitter may be used instead of a dichroic mirror to split the PL light for the individual optical detectors.

[0045] FIG. 5 shows a multi-sensor assembly (or temperature measurement device) 500 having 19 sensors (e.g., 19 sensor assemblies 400), the multi-sensor assembly 500 being attached to a base plate 590 (e.g., a metal base plate) and configured to be installed on the side of a wet processing tank (e.g., wet processing tank 111), whereby the temperature of the wafer 110 can be measured at 19 points, and thereby the temperature uniformity across the wafer 110 can be determined. The metal base plate 590 has sufficient thickness and material thermal conductivity to enable efficient cooling and temperature equalization across all of the sensors 100 or 300 installed thereon. The base plate 590 may comprise a cooling system (not shown), the cooling system may include a strapped cooling manifold, or a fluid cooling system using a manifold embedded within the base plate 590. Alternatively, cooling and temperature regulation may be achieved using a thermoelectric (TE) device or similar device attached to the base plate 590. The base plate 590 may also be configured to attach electronics, an AD converter, a power supply, etc. Alternatively, these components may be attached remotely. In one embodiment, the NIR light source 120 may be remotely located such that the NIR irradiation beam 121 is transmitted to the multi-sensor assembly 500 via an optical fiber. In another embodiment, a single NIR light source 120 may be remotely located and a split optical fiber may be used to provide the NIR irradiation beam 121 to multiple temperature sensors 100 or 300. Similarly, the optical detector (e.g., optical detector 170) as well as the first photodiode PD1 and the second photodiode PD2 may be remotely located and the PL light 115 may be transmitted to them via an optical fiber.

[0046] FIG. 6 shows a multi-sensor assembly 500 attached to a side surface (e.g., the front surface) of a wet processing tank (e.g., wet processing tank 111) in a state of facing a first wafer 110 at one end of a wafer batch and having two nested quartz containers, and the temperature across the wafer 110 at a plurality of irradiation spots can be measured and used for process control. For example, the base plate 590 of the multi-sensor assembly 500 can be arranged substantially parallel to one of one or more wafers of the wafer batch (e.g., the first wafer 110), and the sensors 100 / 300 can determine the temperature distribution across the surface of the first wafer 110 at a plurality of irradiation spots thereon corresponding to the sensors 100 / 300.

[0047] In the configuration of another embodiment shown in FIG. 7, the multi-sensor assembly (or temperature measurement device) 700 can be made long and mounted on another side (e.g., the lateral side) of the wet processing tank 111 facing an edge or area on the wafer surface that is inside of at least one wafer bevel of the wafers 110 of the wafer batch. For example, the base plate 790 of the multi-sensor assembly 700 can be arranged substantially perpendicular to one of the plurality of wafers of the wafer batch, and the sensors 100 / 300 can measure the temperature in the edge or area adjacent to the edge of the wafer 110. In one embodiment, a plurality of sensors (e.g., sensors 100 and 300) can be arranged linearly on the base plate 790 of the multi-sensor assembly 700, and at least one of the plurality of sensors 100 / 300 can face a corresponding edge of the wafer 110 of the wafer batch. In this configuration, by directing the irradiation spots from the individual sensors 100 / 300 towards the edges of the selected wafers within the wafer batch, it is possible to determine the temperature of one or more wafers within the batch. In one embodiment, the plurality of sensors 100 / 300 measure the same point (i.e., the irradiation spot) of each wafer 110. In another embodiment, a plurality of sensors 100 / 300 can be used for each wafer 110 to collect more information regarding the temperature uniformity along the surrounding portion of the wafer accessible from the location of the temperature sensors. In some embodiments, since two adjacent wafers can be spaced apart from each other by a small interval, the plurality of sensors 100 / 300 can measure the temperature of every other wafer of the wafer batch. In various embodiments, the plurality of sensors 100 / 300 can be arranged such that one sensor 100 / 300 covers a plurality of wafers 110.

[0048] Sensors 100 and 300 and sensor assemblies 400, 500, and 700 are specifically suitable for measuring the temperature of a wafer in wet processing tank 111, but similar sensors can also be used to measure the temperature of a wafer and / or other components in other types of semiconductor processing tools (e.g., etching tools, deposition tools, coater-developer systems, dry cleaning systems, heat treatment systems, etc.). In the case of such systems, if necessary, optical access can be provided through a window mounted on the processing chamber or module wall and facing the wafer 110 or component whose temperature is to be monitored. Further, sensors 100 and 300 and sensor assemblies 400, 500, and 700 may be used for in-line temperature monitoring of wafers in a transfer chamber of a semiconductor processing tool or a dedicated measurement station, etc. In some embodiments, additional sensors may be used to examine between wafers 110. It should be further understood that the temperature sensors and multi-sensor assemblies described can also be used in applications not related to semiconductor processing.

[0049] FIG. 8 is a flowchart of an exemplary remote temperature measurement method 800 according to some embodiments of the present disclosure. Aspects of method 800 may be implemented by sensors 100 and 300 and temperature sensor assemblies 400, 500, and 700. In various embodiments, some of the steps of method 800 illustrated may be performed simultaneously or in an order different from that illustrated, may be replaced by other method steps, or may be omitted. Additional method steps can also be performed as desired.

[0050] In step S810, a semiconductor sample is irradiated with near-infrared (NIR) light to excite bandgap photoluminescence (PL) light in the semiconductor sample. For example, wafer 110 may be irradiated with an irradiation beam 121 emitted by NIR light source 120 to excite bandgap PL light 115 in wafer 110.

[0051] In step S820, the spectral intensity of the bandgap PL light is measured. For example, sensors 100 and 300 can be used to measure the spectral intensity of the bandgap PL light 115 excited from the wafer 110.

[0052] In step S830, the temperature of the semiconductor sample is determined based on the measured spectral intensity. For example, the controller can be coupled to the first photodiode PD1 and the second photodiode PD2 (or the optical detector 170) to determine the temperature of the wafer 110 from the acquired PL spectral light intensity.

[0053] In the foregoing description, specific details have been set forth, such as the specific geometric shape of the processing system and descriptions of various components and processes used therein. However, it should be understood that the techniques described herein can be implemented in other embodiments different from these specific details, and such details are for illustrative purposes rather than limitations. The embodiments disclosed herein have been described with reference to the accompanying drawings. Similarly, for purposes of explanation, specific numerical values, materials, and configurations have been shown to obtain a sufficient understanding. However, the embodiments can be implemented without such specific details. Since components having substantially the same functional structure are denoted by like reference numerals, redundant descriptions may be omitted in some cases.

[0054] To assist in the understanding of the various embodiments, various techniques have been described as a plurality of individual operations. The order of the description should not be construed as suggesting that these operations necessarily depend on order. In fact, these operations may not be executed in the presented order. The described operations may be executed in an order different from the described embodiments. Various additional operations may be performed, and / or the described operations may be omitted in additional embodiments.

[0055] As used herein, "substrate" or "target substrate" generally refers to an object to be processed in accordance with the present disclosure. A substrate can include any material portion or structure of a device, particularly a semiconductor device or other electronic device, and can be, for example, a base substrate structure, such as a semiconductor wafer, a reticle, or a layer (such as a thin film) deposited on or overlaid on a base substrate structure. Thus, a substrate is not limited to any particular base structure, underlying layer, or upper layer, whether patterned or not, and is contemplated to include any such layer or base structure, as well as any combination of layers and / or base structures. The above description may refer to a particular type of substrate, but this is for illustrative purposes only.

[0056] One skilled in the art should also understand that various modifications can be made to the operation of the above-described techniques while achieving the same objectives as the present disclosure. Such modifications are intended to be included within the scope of the present disclosure. Accordingly, the above description of embodiments of the present disclosure is not intended to be limiting. Rather, any limitations to embodiments of the present disclosure are set forth in the following claims.

Claims

1. A sensor for remote temperature measurement, comprising: A light source configured to form an irradiation beam; A focusing optical system configured to direct the irradiation beam from the light source to an irradiation spot on a semiconductor sample so that the irradiation beam excites bandgap photoluminescence (PL) light in the semiconductor sample; A condensing optical system configured to condense the bandgap PL light excited from the semiconductor sample; At least one optical detector configured to measure the spectral intensity of the bandgap PL light in the vicinity of the semiconductor bandgap wavelength of the semiconductor sample; A transmission optical system configured to transmit the bandgap PL light from the condensing optical system to the at least one optical detector.

2. The sensor according to claim 1, wherein the transmission optical system includes a notch filter configured to suppress transmission of light at the wavelength of the irradiation beam.

3. The sensor according to claim 1, wherein the transmission optical system includes at least one of a dichroic mirror, a beam splitter, and an optical fiber.

4. The sensor according to claim 1, wherein the focusing optical system and the condensing optical system each utilize the same lens to focus the irradiation beam on the semiconductor sample and to condense the bandgap PL light from the semiconductor sample.

5. The sensor according to claim 1, wherein the light source includes a near-infrared (NIR) laser diode or a light-emitting diode (LED).

6. The sensor according to claim 5, wherein the irradiation beam has a wavelength of 785 nm.

7. The sensor according to claim 1, wherein the at least one optical detector includes a prism spectrometer or a grating spectrometer.

8. The sensor according to claim 1, wherein the at least one optical detector includes at least two single-pixel detectors, each of the at least two single-pixel detectors having an optical bandpass filter disposed in front thereof, and each of the optical bandpass filters being configured to transmit a wavelength or a range of wavelengths in the vicinity of the semiconductor bandgap wavelength of the semiconductor sample.

9. The sensor according to claim 8, wherein the single-pixel detector is a photodiode.

10. The sensor according to claim 9, wherein the photodiode is a silicon (Si) photodiode, a germanium (Ge) photodiode, or an InGaA photodiode.

11. The sensor according to claim 8, wherein the optical band-pass filters of the at least two single-pixel detectors each have a pass-band wavelength of 1050 nm and 1125 nm.

12. The sensor according to claim 1, wherein the semiconductor sample is a semiconductor wafer disposed in a wet processing tank, and the focusing optical system and the condensing optical system are configured to guide the irradiation beam onto the semiconductor wafer through one or more walls of the wet processing tank and through the processing liquid present in the wet processing tank, and to condense the band-gap PL light from the semiconductor wafer.

13. The sensor according to claim 12, wherein the one or more walls are nested and contain quartz.

14. The treatment liquid contains H ３ PO ４ 、H ２ O、H ２ O ２ 、and H ２ SO ４ The sensor according to claim 12, which contains at least one of them.

15. The sensor according to claim 1, further comprising a controller configured to acquire the PL spectrum light intensity from the at least one optical detector and determine the temperature of the semiconductor sample from the acquired PL spectrum light intensity.

16. A base plate; A temperature measuring device comprising a plurality of sensors according to claim 1, attached to the base plate and disposed across the base plate and configured to measure the temperature of one or more semiconductor samples.

17. The temperature measuring device according to claim 16, wherein the base plate is disposed substantially parallel to one of the one or more semiconductor samples, and the sensor is configured to determine a temperature distribution across a surface of one of the one or more semiconductor samples at a plurality of irradiation spots thereon corresponding to the sensor.

18. The temperature measuring device according to claim 16, wherein the base plate is disposed substantially perpendicular to the one or more semiconductor samples, and the sensor is configured to measure the temperature at at least one edge of the one or more semiconductor samples or in a region proximate to the edge.

19. The temperature measuring device according to claim 16, further comprising a temperature control system configured to control the temperature of the base plate and the sensor.

20. The temperature measuring device according to claim 19, wherein the temperature control system includes a temperature-controlled fluid manifold that contacts the base plate or is incorporated within the base plate.

21. The temperature measuring device according to claim 19, wherein the temperature control system comprises one or more thermoelectric (TE) devices that contact the base plate.

22. A wet semiconductor processing bath, The temperature measuring device according to claim 18, configured to measure the temperature of one or more semiconductor samples disposed within the wet semiconductor processing bath through one or more walls of the wet semiconductor processing bath and through the processing liquid of the wet semiconductor processing bath, and a wet semiconductor processing system including the same.

23. Irradiating a semiconductor sample with an irradiation beam to excite bandgap photoluminescence (PL) light in the semiconductor sample; Measuring the spectral intensity of the excited bandgap PL light from the semiconductor sample; A remote temperature measurement method including determining the temperature of the semiconductor sample based on the measured spectral intensity.

24. The method according to claim 23, wherein measuring the spectral intensity of the bandgap PL light includes measuring the spectral intensity of the bandgap PL light at two wavelengths or two ranges of wavelengths in the vicinity of the semiconductor bandgap wavelength of the semiconductor sample.

Images