Adjustable achromatic collimator assembly for end-point detection systems

Abstract

Implementations disclosed herein describe a collimator assembly having a collimator housing including an interface configured to optically couple to a process chamber having a target surface; and a port receiving an optical fiber to deliver a first (second) plurality of spectral components of light belonging to a first (second) wavelength range to an enclosure formed by the collimator housing, and an achromatic lens at least partially located within the enclosure formed by the collimator housing, the achromatic lens directing the first (second) plurality of spectral components of light onto the target surface to illuminate a first (second) region on the target surface, wherein the second region is substantially the same as the first region.

Description

[0001] This application is a divisional application of application number 202180059442.1, filed on August 10, 2021, entitled "Adjustable color difference-free collimator assembly for an endpoint detection system". Technical Field

[0002] This specification generally relates to the fabrication of integrated circuits and other semiconductor devices in processing chambers. More specifically, this specification relates to adjustable endpoint detection systems for precise product control in device manufacturing. Background Technology

[0003] The fabrication of microelectronic and integrated circuit components typically involves performing numerous operations on semiconductor, dielectric, and conductive substrates. Examples of these operations include oxidation, diffusion, ion implantation, thin film deposition, cleaning, etching, photolithography, and more. Materials manufactured in this manner can include single crystals, semiconductor films, fine coatings, and many other substances used in electronic device fabrication and other practical applications. As selected types of atoms are added (e.g., by deposition) to or removed from a substrate (e.g., by etching), efficient and precise endpoint monitoring techniques (and systems) become valuable. Insufficient etching and excessive etching (and similarly, insufficient and excessive deposition) can lead to substandard or even failed devices. Optical control systems can monitor various stages of component fabrication in real time, significantly improving product quality. This is particularly useful given the ever-increasing demands on the quality of semiconductor devices. Summary of the Invention

[0004] In one implementation, this application discloses a collimator assembly including a collimator housing and an anachromatic lens. The collimator housing includes an interface and a port, the interface being configured to be optically coupled to a processing chamber having a target surface, and the port receiving an optical fiber. The optical fiber is used to transmit a first plurality of spectral components of light belonging to a first wavelength range and a second plurality of spectral components of light belonging to a second wavelength range to the housing formed by the collimator housing. The first range is within a wavelength range of 400-700 nm, while the second range is outside the 400-700 nm wavelength range. The anachromatic lens is at least partially located within the housing formed by the collimator housing. The anachromatic lens directs the first plurality of spectral components of light onto the target surface to illuminate a first region on the target surface. The anachromatic lens further directs the second plurality of spectral components of light onto the target surface to illuminate a second region on the target surface, such that the second region is substantially identical to the first region.

[0005] In another implementation, this application discloses an endpoint detection system comprising a light source, a collimator housing, an achromatic lens, a photodetector, and a processing device. The light source outputs a first plurality of spectral components of light belonging to a first wavelength range and a second plurality of spectral components of light belonging to a second wavelength range. The first range is within the 400-700 nm wavelength interval, while the second range is outside the 400-700 nm wavelength interval. The collimator housing includes an interface configured for optical coupling to a processing chamber having a target surface. The collimator housing also includes a port for receiving optical fibers to transmit the first plurality of spectral components of light belonging to the first wavelength range and the second plurality of spectral components of light belonging to the second wavelength range to a housing formed by the collimator housing. The achromatic lens is at least partially located within the housing formed by the collimator housing. The achromatic lens directs the first plurality of spectral components of light onto the target surface to illuminate a first region on the target surface, and directs the second plurality of spectral components of light onto the target surface to illuminate a second region on the target surface, such that the second region is substantially identical to the first region. A second optical fiber is used to collect from the target surface a first plurality of reflected spectral components of light generated by a first plurality of spectral components of light guided to the target surface. The second optical fiber is further used to collect from the target surface a second plurality of reflected spectral components of light generated by a second plurality of spectral components of light guided to the target surface. A photodetector is used to receive the first plurality of reflected spectral components and the second plurality of reflected spectral components of light via the second optical fiber. A processing device communicatively coupled to the photodetector determines the reflectivity of the target surface based on the received first plurality of reflected spectral components and the received second plurality of reflected spectral components of light.

[0006] In another implementation, this application discloses a method for outputting a first plurality of spectral components of light belonging to a first wavelength range and a second plurality of spectral components of light belonging to a second wavelength range from a light source. The first range is within the wavelength interval of 400-700 nm, while the second range is outside the wavelength interval of 400-700 nm. The disclosed method further guides the first plurality of spectral components of light onto a target surface using an achromatic lens, so that a first region on the target surface is illuminated. The disclosed method further guides the second plurality of spectral components of light onto the target surface using an achromatic lens, so that a second region on the target surface is illuminated, such that the second region is substantially the same as the first region. The disclosed method further collects from the target surface a first plurality of reflected spectral components of light generated by the first plurality of spectral components of light guided onto the target surface via a second optical fiber. The disclosed method further collects from the target surface a second plurality of reflected spectral components of light generated by the second plurality of spectral components of light guided onto the target surface via a second optical fiber. The disclosed method further receives the first plurality of reflected spectral components and the second plurality of reflected spectral components of light via a photodetector through the second optical fiber. The disclosed method further determines the reflectivity of the target surface by a processing device communicatively coupled to a photodetector based on a first plurality of reflection spectral components of the received light and a second plurality of reflection spectral components of the received light. Attached Figure Description

[0007] Figure 1 A manufacturing machine according to some implementations of the present disclosure is schematically shown, the manufacturing machine including a spatially adjustable broadband collimator assembly for precise optical characterization of a target material within a processing chamber.

[0008] Figure 2 An exemplary chromatic aberration (wideband) collimator assembly according to some implementations of this disclosure is schematically shown for precise optical characterization of a target material within a processing chamber.

[0009] Figures 3A-3D The advantages of using a chromatic aberration (wideband) collimator for accurate optical characterization of the target material in the processing chamber, compared to conventional collimators, are illustrated schematically in some implementations of this disclosure.

[0010] Figure 4 An exemplary collimator assembly according to some implementations of this disclosure is schematically shown, the collimator assembly having an adjustable alignment element for precise optical characterization of a target material within a processing chamber.

[0011] Figure 5 An exemplary tilted collimator assembly according to some implementations of this disclosure is schematically shown, the collimator assembly having an adjustable alignment element for precise optical characterization of a target material within a processing chamber.

[0012] Figure 6 The illustration schematically shows a side view of an exemplary collimator assembly with an adjustable alignment element according to some implementations of this disclosure.

[0013] Figure 7 This is a flowchart of one possible implementation of a method for deploying a wideband collimator assembly to perform precise optical characterization of a target within a processing chamber, according to some implementations of this disclosure.

[0014] Figure 8 This is a flowchart of one possible implementation of a method for precisely optically characterizing a target material within a processing chamber by adjusting the tilt of an adjustable collimator assembly according to some implementations of this disclosure.

[0015] Figure 9 A block diagram of an example processing system capable of supporting real-time detection of particulate contaminants present in a deposition chamber based on light scattering data is depicted. Detailed Implementation

[0016] The implementation disclosed herein provides precise, wide-band optical endpoint control in semiconductor device fabrication. This implementation enables the delivery of a light beam with a uniform spatial distribution across a wide range of wavelengths into a processing chamber. For example, the beam width of the 250 nm spectral component of the beam can be the same as the beam width of the 750 nm spectral component. Spatial uniformity of the beam is achieved by transmitting the optical signal through a collimator equipped with a wide-band chromatic aberration-free lens. This enhanced uniformity ensures more accurate measurement of the optical response of a target material (such as a substrate) within the processing chamber (compared to collimators with conventional optical elements), and thus ensures more accurate determination of the target material's state (e.g., during substrate etching or deposition processes).

[0017] The collimator may be further equipped with a precision adjustment mechanism for adjusting the alignment of the collimator's optical axis to maximize the efficiency of delivering incident light to the desired area on the target located within the processing chamber. In some implementations, after maintenance of the processing chamber is performed, the adjustment mechanism may be used to compensate for minor differences in the position of the processing tool (such as changes in the positioning of the chuck used for wafer support) caused by tool disassembly, reassembly, and / or recalibration.

[0018] During electronic device manufacturing, multiple patterning transfer operations are frequently performed, including photolithography and etching. For example, in a photolithography step, a photoresist layer, partially protected by a photomask (containing the desired pattern), is exposed to a light source and subsequently developed in a suitable chemical solution to remove the exposed, unprotected portions of the photoresist. The resulting patterned photoresist layer can then be used as a mask in an etching step to protect a substrate (e.g., a silicon wafer) exposed to a reactive environment (e.g., wet or dry etching), thereby removing unprotected portions of the substrate. During etching, endpoint data from the substrate (such as optical response data, which may include reflection data, polarization data, etc.) can be used to determine whether the process is operating according to specifications and whether desired results, such as etching depth and uniformity, have been achieved.

[0019] Variations in the reaction environment (such as composition, temperature, and plasma density) and differences in photomask patterns can lead to variations in etching rate and uniformity. Tracking these variations requires an accurate and tunable optical endpoint system capable of collecting precise and extensive optical response data characterizing various target surfaces (wafers, photomasks, etc.) within the processing chamber. The continuous shrinking of microelectronic device dimensions, the increasing complexity of photomask designs, and the ever-growing demands for device uniformity further drive the pursuit of accuracy. Existing optical systems for endpoint control are generally inadequate to meet these increasing technological requirements.

[0020] The aspects and implementations disclosed herein address this and other drawbacks of optical inspection techniques that may be used in substrate manufacturing. This document describes a spatially adjustable optical inspection apparatus capable of transmitting a beam with a uniform spatial distribution over a wide wavelength range for precise optical characterization of substrate processing. The implementations disclosed herein facilitate accurate determination of the optical, physical, and / or morphological properties of substrates, such as substrate uniformity, smoothness, thickness, refractive index, reflectivity, etc., and provide an effective quality control tool without slowing down the manufacturing process.

[0021] The disclosed implementations involve various manufacturing techniques using processing chambers (which may include deposition chambers, etching chambers, etc.), such as chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma-enhanced chemical vapor deposition (PECVD), plasma-enhanced physical vapor deposition (PEPVD), sputtering deposition, atomic layer chemical vapor deposition, combustion chemical vapor deposition, catalytic chemical vapor deposition, evaporation deposition, and molecular beam epitaxy. The disclosed implementations can be used in techniques using vacuum deposition chambers (e.g., ultra-high vacuum chemical vapor deposition or physical vapor deposition, low-pressure chemical vapor deposition, etc.) as well as in atmospheric pressure deposition chambers.

[0022] Figure 1 A manufacturing machine 100 according to some implementations of the present disclosure is schematically illustrated, the manufacturing machine including a spatially adjustable broadband collimator assembly for precise optical characterization of a target within a processing chamber. In one implementation, the manufacturing machine 100 includes a processing chamber 102 within a processing chamber housing 104 for processing (e.g., deposition, photolithography, etching, etc.) one or more substrates 106. During processing, the substrate 106 may be exposed to a plasma environment 110 for plasma-enhanced processing, such as etching. The substrate 106 may be supported by a suction cup 108. The processing chamber 102 may include one or more processing kit tools 112, such as edge rings, etc. The substrate 106 may be lifted by lifting pins (not shown) to expose the target on the rear surface of the substrate 106 to the processing environment for heating the substrate 106 (e.g., by irradiating the substrate with guide light), etc.

[0023] The processing of substrate 106 in processing chamber 102 can be optically monitored via an endpoint optics system including collimator assembly 120 and control module 130. Collimator assembly 120 may be mechanically coupled to processing chamber housing 104 (rigidly or operably coupled, as explained in more detail below) and optically interfaced with the environment of processing chamber 102 (such as plasma environment 110). The optical interface between collimator assembly 120 and processing chamber 102 may be an aperture, a converging or diverging lens, a transparent plate (which may be without optical power), a polarizer, or any other device or material capable of transmitting light between collimator assembly 120 and processing chamber 102. In this document, “light” means electromagnetic radiation of any spectral range, including visible light, far-infrared and near-infrared, far-ultraviolet and near-ultraviolet, etc. “Light” may further include unpolarized (e.g., natural) light, linearly polarized light, circularly polarized or elliptically polarized light, partially polarized light, focused light, diverging light, collimated light, etc.

[0024] Collimator assembly 120 can generate beam 122 from input light 124 generated by light source 132. In some implementations, input light 124 is transmitted via one or more input optical fibers. Light source 132 can be a narrowband light source, such as a light-emitting diode, laser, bulb, etc. In some implementations, light source 132 is a broadband light source. In some implementations, light source 132 includes more than one component light source, such as multiple narrowband light sources that generate (when combined) broadband input light 124. Light source 132 may include additional optical elements to control the spectral distribution and / or polarization of input light 124 (such as filters, absorbers, polarizers, etc.).

[0025] In some implementations, the input light 124 is converted into a beam 122 by a collimator assembly 120, for example, by passing the input light 124 through multiple optical elements (such as lenses, reflectors, filters, apertures, etc.) of the collimator assembly 120. The collimator assembly 120 may have wide-band characteristics. More specifically, the collimator assembly 120 may produce a beam 122 (described in more detail below) whose spatial extent can be the same for multiple spectral components of the beam. For example, the diameter of the produced beam 122 may be the same over a wide wavelength λ range in the input light 124 and therefore over the various spectral components contained in the beam 122. In existing endpoint detection systems, the diameter of a conventional beam 122-1 varies depending on the wavelength λ. For example, the green component (λ = 550 nm) may have a diameter of 9 mm, while the red component (λ = 650 nm) may have a diameter of 13 mm. (This is in...) Figure 1The diagram schematically illustrates the varying shading in the depiction of a conventional light beam 122-1. Therefore, different spectral components propagate along different optical paths. This can lead to significant errors in the obtained substrate reflectivity R(λ), and consequently, may result in incorrect characterization of the target material (e.g., the surface of substrate 106) and errors in the etching process (such as causing etching to stop too early or too late).

[0026] In contrast, this disclosure describes a wide-band collimator assembly 120 that ensures that the various spectral components λ of the beam 122 have substantially the same spatial range. This is in Figure 1 A schematic cross-section of a uniform white beam 122-2 is shown in the diagram. To achieve this wideband chromatic aberration beam output, the collimator assembly 120 may have one or more chromatic lenses, as referenced below. Figure 2 A more detailed description. More specifically, the chromatic light beam 122-2 can be characterized by the beam spectral content of specifying multiple spectral ranges Δλ (e.g., a spectral range with a width Δλ = 100 nm (or 150 nm, 200 nm, or any other wavelength range)). The spectral range can be centered on a sequence of center wavelengths λ1, λ2, λ3… In some implementations, the ranges overlap when Δλ is greater than the distance between adjacent center wavelengths. In some implementations, Δλ is equal to the distance between center wavelengths (e.g., Δλ = λ3 - λ2). In some implementations, Δλ is greater than the distance between center wavelengths (therefore the ranges do not overlap). In some implementations, the ranges Δλ have unequal widths. (Or, the ranges may correspond to equal frequency intervals Δf). In some implementations, the range Δλ corresponds to the actual emission range of various light emitters of the light source 132 (e.g., the emission range of the light-emitting diodes of the light source 132). In other implementations, the range Δλ is defined only for characterization purposes and may not be limited to any particular physical light emitter.

[0027] With λ k The range of the center △λ k The spectral components within a certain diameter d can be k The spectral beam propagates in the form of a circular cross-section. (For simplicity, the beam will be described as having a circular cross-section. However, it should be understood that a similar characterization can be made for beams with any other cross-section, such as elliptical beams or beams with some other shape). The k-th spectral beam can illuminate the k-th region A on the target surface (e.g., the surface of substrate 106). k Symbol A k This can represent the area of ​​the illuminated region or some other geometric feature of the illuminated region. The diameter and / or area of ​​the k-th illuminated region can be defined using any suitable scheme, as long as the same scheme is used across various spectral ranges. For example, the half-width or full width at half-width of the continuous distribution of the intensity of the k-th spectral beam can be used to determine the diameter d.k In some implementations, to ensure they are largely identical, the two lighting areas A... k and A m There will be at least 90% (or 85%, 95%) overlap. That is, region A. k Located in area A m The portion outside (and vice versa) is smaller than region A. k 10% (or 15%, 5%).

[0028] In some implementations, to achieve chromatic aberration-free wide-band characteristics, the collimator assembly 120 generates at least two spectral beams that illuminate substantially the same region on the target surface. In some implementations, to achieve chromatic aberration-free wide-band characteristics, the two spectral beams correspond to ranges spaced apart by a center-to-center wavelength interval of at least 200 nm. In some implementations, to achieve chromatic aberration-free wide-band characteristics, the collimator assembly 120 generates at least three spectral beams that illuminate substantially the same region on the target surface. In some implementations, the three spectral beams correspond to ranges spaced apart by a wavelength interval of at least 400 nm between the centers of the two outermost ranges.

[0029] Light reflected from the target surface can pass in the opposite direction through the collimator assembly 120 and be collected by one or more second optical fibers. The second optical fibers can transmit the output light 126 to a photodetector 134 for spectral analysis. The photodetector 134 may include one or more spectrometers, spectrometers, diffraction gratings, mirrors, lenses, photodiodes, and other devices. The photodetector 134 may determine one or more optical responses of the target material, either alone or in conjunction with a processing device 136 (e.g., a central processing unit (CPU), microcontroller, application-specific integrated circuit (ASIC), digital signal processor (DSP), field-programmable gate array (FPGA), or any other type of processing device). The optical response may include reflectivity R(λ), refractive index n(λ), or any other optical quantity that can be used to characterize the substrate, such as the polarization dependence of reflectivity, the rotation angle of the polarization plane during reflection, luminous intensity, etc.

[0030] Processing device 136 can communicate with memory element 138. In some implementations, memory element 138 stores instructions to be executed by processing device 136 to cause light source 132 to generate input light 124, to cause photodetector 134 to perform detection of output light 126, and to perform any further operations that may be required for substrate processing. Such operations may include starting, stopping, and / or resuming etching, photolithography, or deposition operations. Processing device 136 may be the same processing device that controls operations within processing chamber 102, or a separate dedicated processing device for an endpoint detection system.

[0031] In some implementations, the collimator assembly 120 is equipped with a tilt adjustment mechanism 128 to allow the optical axis of the collimator to be aligned (in Figure 1 Adjustments are made (depicted in dashed lines) to facilitate collimator centering (or recentering) after maintenance when the collimator assembly 120 is moved to different processing chambers, or to ensure consistency between chambers. In some implementations, see the following references. Figures 4-6 The tilt adjustment mechanism 128 includes one or more adjustment screws that facilitate a configurable connection between the collimator assembly 120 and the processing chamber housing 104.

[0032] Figure 2 An exemplary chromatic aberration (wideband) collimator assembly 200 according to some implementations of this disclosure is schematically shown for precise optical characterization of a target material within a processing chamber. Figure 2 It is not drawn to scale and is intended only as an illustrative representation. In various implementations, this can be omitted. Figure 2 Some components are shown. For clarity and simplicity, some additional components known to those skilled in optical inspection techniques may not be shown. Figure 2 As shown in the diagram, but in reality, it may exist in various implementations. In some implementations, the collimator component 200 corresponds to... Figure 1The collimator assembly 120. The collimator assembly 200 may have a collimator housing 202. The collimator housing 202 may have a chamber interface 204 for coupling the collimator assembly 200 to a processing chamber (e.g., processing chamber 102). In some implementations, the chamber interface 204 may be permanently fused to the collimator housing 202, or may be an extension of the collimator housing 202. In some implementations, the chamber interface 204 is removably attached to the collimator housing 202 by threads, or secured to the collimator housing by friction or retaining screws, pins, stops, etc. The chamber interface 204 may be fitted into a receiving port in the processing chamber housing 102 and may be sealed (by one or more hermetic seals or gaskets) to the receiving port to prevent gas from escaping from the environment of the processing chamber. In some implementations, the chamber interface 204 is sealed to an opening in the processing chamber housing 102, wherein the seal(s) allow the axis of the collimator housing 202 to tilt away from the vertical direction within a set limit, but without compromising the isolation between the internal environment of the processing chamber 102 and the external atmosphere.

[0033] Collimator housing 202 may define a housing for accommodating various optical elements of collimator assembly 200, such as chromatic aberration (wideband) lens 210, optical filler 212, optical interface 214, etc. As shown, the top of collimator housing 202 may have an opening to guide one or more optical fibers 208 (to transmit input light 124 and / or receive output light 126) via a conduit in a guide cap. In some implementations, optical fibers 208 may enter the housing of the collimator assembly in different ways, such as through the sidewall of housing 202. Optical interface 214 may include openings, waveguides, lenses, etc. Optical interface 214 may be configured to allow light to pass through but prevent contaminants from entering. For example, upon exiting optical fiber 208, input light 124 may pass through an optically transparent material plate (film) or a diverging (converging) lens, which may mechanically seal the conduit of the optical fiber.

[0034] The chromatic aberration lens 210 can be a wide-band lens, designed to minimize chromatic aberration over a wide wavelength range. For example, the chromatic aberration lens 210 can have multiple lenses made of different materials, some of which have high refractive index dispersion, while others have low dispersion. In some implementations, the chromatic aberration lens 210 can be a double lens with two optical elements (e.g., a converging lens and a diverging lens). In some implementations, such as... Figure 2 As shown, the chromatic aberration lens 210 can be a triple lens with three optical elements. In some implementations, the chromatic aberration lens 210 can have more than three optical elements. The chromatic aberration lens 210 can be designed for two, three, or more reference wavelengths Λ1, Λ2, Λ3... to have the same focal point (e.g., reference wavelengths Λ1, Λ2, Λ3...). Figure 1Some or all of the reference wavelengths may be the center wavelength used to characterize beam 122. This ensures that a small chromatic aberration is maintained even for wavelengths falling between the reference wavelengths. The focusing distances of various elements of the chromatic lens 210 can be selected such that the input light transmitted through the optical fibers 208 becomes a collimated beam after passing through the chromatic lens 210. In other embodiments, the appropriately selected distance between the optical fiber 208 and the chromatic lens 210 can be used to ensure that the output beam (e.g., beam 122-2) is collimated. In some implementations, one or more lenses of the optical interface 214 contribute to collimation.

[0035] In some implementations, the chromatic lens 210 is secured within the collimator housing 202 by a retaining ring. In some implementations, the chromatic lens is screwed into the threaded portion of the collimator housing 202. In some implementations, the chromatic lens 210 is frictionally secured by the collimator housing 202. For example, the diameter of the chromatic lens 210 may be precisely tailored to the inner diameter of the housing formed by the collimator housing 202, such that the lens maintains sufficient lateral tension to generate adequate friction to securely hold the lens in place. In some implementations, the space between the chromatic lens 210 and the optical interface 214 is filled with a transparent optical filler 212 to ensure optical path consistency (e.g., minimizing the presence of air, moisture, and other possible contaminants along the optical paths of the input and output light signals).

[0036] Figure 3 schematically illustrates the advantages of using an achromatic (wideband) collimator for accurate optical characterization of the target material within the processing chamber, according to some implementations of this disclosure, compared to conventional collimators. Figure 3A The figure shows a description of the reflectance R(λ) data of a reference substrate obtained for a wavelength λ continuous region from near ultraviolet to near infrared (e.g., 200-800 nm in one example). Figure 3A The measurement data schematically shown are obtained using a conventional collimator without a chromatic aberration lens. The dashed line represents the reference reflectance of the same reference substrate obtained in a laboratory environment using an advanced light source and a light-detection spectrometer, through high-precision reflectance measurements. Figure 3A The solid line in the figure represents data obtained using a conventional collimator that generates a beam (such as beam 122-1), the spatial range of which is uncontrolled at different wavelengths. A comparison of the two curves shows that while the measured reflectance is quite close to the exact reference reflectance in the blue portions of the ultraviolet and visible light ranges, the accuracy drops significantly in the red portion of the visible spectrum and becomes very poor in the infrared range.

[0037] Figure 3B The image shows the use of, as Figures 1-2The measurement results of the reflectivity R(λ) of the wideband collimator with chromatic aberration lens on the same reference substrate. Figure 3B The improvement shown stems from irradiating the target substrate with a beam (e.g., beam 122-2) that has a substantially uniform spatial extent across the entire wavelength λ continuous region used in target characterization. The table below illustrates the improvements in beam uniformity at several wavelengths.

[0038]

[0039] Improved beam uniformity helps to determine reflectivity R(λ) more accurately. Due to the more accurate measurement of reflectivity, processing device 136 can accurately determine the current state of processing operations (deposition, etching, etc.) performed on the actual substrate in processing chamber 102.

[0040] Figure 3C The diagram illustrates the spatial extent of a conventional light beam (e.g., beam 122-1) with two exemplary spectral components, represented as visible light (e.g., 550 nm) and near-infrared light (e.g., 750 nm). The position indicated by the horizontal axis can be a radial distance from the beam center. As shown, the spatial extent of the two spectral components (e.g., the distance corresponding to half the beam width) can differ significantly. Conversely, Figure 3D The figure illustrates the spatial extent of the beam (e.g., beam 122-2) output by a broadband collimator assembly (e.g., assembly 120) for the same two spectral components. As shown, the spatial extents of the two spectral components are substantially the same.

[0041] Figure 4 An exemplary collimator assembly 400 according to some implementations of the present disclosure is schematically shown, the collimator assembly 400 having an adjustable alignment element for precise optical characterization of a target material within a processing chamber. Figure 4 This is not drawn to scale and is intended only as an illustrative representation. In various implementations, this may be omitted. Figure 4 Some components are shown. For clarity and simplicity, some additional components known to those skilled in optical inspection techniques may not be listed. Figure 4 As shown, but may actually exist in various embodiments. In some embodiments, the collimator element 400 may be... Figure 2 The collimator element 200. The collimator assembly 400 may be configured to be optically coupled to a processing chamber (such as processing chamber 102). The collimator assembly 400 may include a collimator housing 402. The collimator housing 402 may have a chamber interface 404 for coupling to the processing chamber. The chamber interface 404 may allow a degree of variability (within set limits) in the direction of the collimator axis (which may also be the collimator optical axis contained within a housing formed by the collimator housing 402).

[0042] Figure 5 An exemplary tilted collimator assembly 500, according to some implementations of this disclosure, is schematically shown. The collimator assembly has adjustable alignment elements for precise optical characterization of a target within a processing chamber. Figure 5 As shown, the collimator axis 405 can be tilted from the reference axis 407 (shown by dashed lines) to an angle θ. Figure 5 The image depicts a vertical reference axis 407, but in various implementations, the reference axis may be oriented in any other suitable direction. For example, in some implementations where the collimator assembly 400 is coupled to the sidewall of the processing chamber 102, the reference axis may be horizontal. For ease of illustration, Figure 5 The tilt angle shown is magnified. In some implementations, the maximum tilt angle may be 1° (or less than 1°). In some implementations, the tilt angle may be greater than 1° and may be limited by many factors, such as the expected requirement for a large tilt angle and the ability of a given chamber interface 404 to maintain proper airtightness with the processing chamber 102.

[0043] In some implementations, the tilt adjustment mechanism includes one or more adjustment mechanisms 403 to control the tilt (alignment) of the collimator shaft 405. The term "adjustment mechanism" herein means any mechanical device (such as a screw, bolt, lever, wedge, etc.) or combination of mechanical devices capable of converting the rotational motion of a control head (e.g., the head of a screw, knob, etc.) into the parallel motion of a mechanical component (such as the shaft of a screw, spring, wedge, etc.). The mechanical component may interface between a movable portion of the collimator housing 402 and a fixed portion of the collimator housing. In some implementations, the mechanical component interfaces directly between the movable portion of the collimator housing 402 and the processing chamber housing 104 (or any portion connected to the housing). In some implementations, for precise control of the collimator tilt angle θ, the adjustment mechanism 403 may be equipped with a micrometer head or any other device that provides appropriate feedback on the tilt angle and allows reproducible adjustment of the collimator assembly 400. Because, geometrically, any three arbitrarily placed points define a plane, in some implementations, the number of adjustment mechanisms 403 is three. In some implementations, the number of adjustment mechanisms 403 is less than three. For example, the adjustment screw 403(1) can be replaced by a non-adjustable screw (or pin) that remains in fixed contact with the processing chamber shell, while adjustment mechanisms 403(2) and 403(3) ( Figures 4-5 (Not shown in the image) Fully adjustable tilt control is still permitted. Therefore, the collimator axis 405 can still tilt in two directions, allowing the collimator axis to tilt away from the reference axis 407 by an angle θ and rotate about the reference axis. .

[0044] Figure 6 A side view 600 of an exemplary collimator assembly with an adjustable alignment element according to some implementations of this disclosure is schematically shown. Figure 6 It is not drawn to scale and is intended only as an illustrative representation. In various implementations, this can be omitted. Figure 6 Some components are shown. For clarity and simplicity, some additional components known to those skilled in optical inspection techniques may not be listed. Figure 6 As shown in the diagram, but in reality, it may exist in various implementations. In some implementations, the side view 600 can be its top view 500. Figure 5 The collimator assembly shown in the image.

[0045] like Figure 6 As shown, in some implementations, the first housing support 602-1 may be rigidly coupled to the collimator housing 602. The second housing support 602-2 may be attached to the processing chamber housing (not shown). One or more of the tilt adjustment screws 603 may operatively connect the first housing support 602-1 to the second housing support 602-2. In some implementations, a tension spring 614 is used in conjunction with the adjustment screws 603, as shown. In some implementations, the tension spring 614 is positioned differently from the position of the adjustment screws 606. The tension spring 614 may be held in a compressed state such that the total force exerted (upward) on the first housing support 602-1 is greater than (in some implementations, significantly greater than) the total weight of the collimator assembly. This spring compression helps stabilize the first support relative to the second support and prevents the collimator assembly from wobbling during operation of the endpoint detection device. Operation of one or more of the alignment screws 603 may result in a desired tilt of the collimator optical axis, similar to the operation described above regarding... Figure 4 The described operation.

[0046] To accommodate movement of the first shell support 602-1 relative to the second shell support 602-2, a tilt-enabling clearance 616 may be implemented. The tilt-enabling clearance 616 may extend symmetrically about the circumference of the shell 602 (if the shell has a cylindrical shape) or may be designed to be asymmetrical. When one or more tilt adjustment screws are operated (e.g., by a human operator) and the shell 602 is tilted, this allows free tilting until further adjustment is prevented by the shell body in contact with the second shell support 602-2. The amount of clearance 616 may be set to allow a maximum predetermined tilt. For example, if the height of the second shell support 602-2 near the clearance 616 is 0.3 inches, a clearance of 0.005 inches may allow a tilt of up to 1° away from a reference (e.g., vertical) direction (beyond a full 360° azimuth tilt).

[0047] Figure 7This is a flowchart illustrating one possible implementation of method 700 according to some implementations of this disclosure, wherein method 700 deploys a wideband collimator assembly for precise optical characterization of a target within a processing chamber. In some implementations, the wideband collimator assembly is spatially adjustable. Method 700 may use... Figures 1-6 The method 700 may be performed using the systems and components described herein, or any combination thereof. In some embodiments, some or all of the steps of method 700 may be performed in response to instructions from processing device 136. Processing device 136 may be coupled to one or more memory elements 138. In some implementations, method 700 may be performed while a substrate is being processed in processing chamber 102. In some implementations, method 700 may be performed while a calibration device or reference substrate is located in processing chamber 102.

[0048] Method 700 may involve outputting an optical signal from a light source (operation 710). In some implementations, a processing device (e.g., device 136) causes the light source to output an optical signal. In other implementations, a human operator causes the optical signal to be output. The optical signal may have a broad spectral distribution (or be a set of multiple narrowband distributions). The optical signal may include multiple wavelength ranges, such as [λ...]. -△λ / 2, λ + △λ / 2], where j=1, 2, 3… Each range can be determined by its center wavelength λ. and width △λ The range is characterized by multiple spectral components. The number of components within each range can be very large, or even infinite, because spectral components can be represented as a continuous region (which can be characterized by Fourier integrals).

[0049] At operation 720, method 700 may continue to guide a first plurality of spectral components of light belonging to the interval [λ1 - Δλ1 / 2, λ1 + Δλ1 / 2] onto the target surface so that a first region on the target surface is irradiated. Similarly, at operation 730, method 700 may continue to guide a second plurality of spectral components of light belonging to the interval [λ2 - Δλ2 / 2, λ2 + Δλ2 / 2] onto the target surface so that a first region on the target surface is irradiated. The first plurality of spectral components and the second plurality of spectral components may be transmitted to a broadband collimator via one or more first optical fibers. The collimator may have a chromatic aberration-free lens. After passing through the broadband collimator, the first beam including the first plurality of spectral components (which may be a collimated beam, a focused beam, or a diverging beam) may have a cross-section substantially the same as that of the second beam including the second plurality of spectral components. Thus, the first region on the target surface irradiated by the first beam (e.g., a substrate that has been etched or otherwise treated) may be substantially the same as the second region on the target surface irradiated by the second beam. Operations 720 and 730 can be executed in any order. In some implementations, operations 720 and 730 can be executed simultaneously. In some implementations, operations 720 and 730 can be executed sequentially, one after the other.

[0050] Each beam directed at the target surface allows the corresponding reflected beam to propagate back through a collimator and be received by one or more second optical fibers for transmission to a photodetector. More specifically, at operation 740, the first reflected beam (which includes a first plurality of reflected spectral components reflected from the target surface) can be collected by one or more second optical fibers. Similarly, at operation 750, the second reflected beam (which includes a second plurality of reflected spectral components reflected from the target surface) can be collected by one or more second optical fibers. The first (second) reflected beam can be generated by the first (second) plurality of spectral components of light incident on the target surface. Operations 740 and 750 can be performed in any order. In some implementations, operations 740 and 750 can be performed simultaneously. In some implementations, operations 740 and 750 can be performed sequentially, one after the other.

[0051] At operation 760, method 700 may continue by receiving a first plurality of reflection spectral components and a second plurality of reflection spectral components of light via a photodetector through a second optical fiber. At operation 770, the photodetector (in some implementations, combined with a processing device and / or a memory) may determine the reflectivity of the target surface based on the first plurality of reflection spectral components and the second plurality of reflection spectral components of the received light. In some implementations, the reflectivity may be determined over the entire width of a first wavelength range and the entire width of a second wavelength range. In some implementations, additional wavelength ranges (e.g., a third, fourth, etc.) may be used in a manner similar to those described above to obtain a more accurate characterization of the target surface. In some implementations, the first range is within the 400-700 nm wavelength range, while the second range is outside the 400-700 nm wavelength range. In some implementations, the third range is outside the 400-700 nm wavelength range and is different from the second range. In some implementations, the second (or third) range is in the 100-400 nm range, while the third (second) range is in the 700-900 nm wavelength range.

[0052] Figure 8 This is a flowchart of one possible implementation of method 800 according to some implementations of this disclosure, wherein method 800 adjusts the tilt of an adjustable collimator assembly for precise optical characterization of a target material within a processing chamber. In some implementations, method 800 uses Figures 1-6 The system and components described herein, or any combination thereof, may be used to perform this action. In some implementations, some or all of the steps of method 800 may be performed in response to instructions from processing device 136.

[0053] At operation 810, method 800 may detect a processing chamber setup event. For example, the processing chamber may have been serviced (e.g., scheduled or unscheduled maintenance may have been performed), one or more processing chamber components may have been replaced, or the collimator assembly may have been moved and coupled to a different chamber. In some implementations, the "setup event" may be a setup check event not associated with any setup modification, but may be an indication of a routine check of the schedule (or an operator-requested check).

[0054] At operation 820, method 800 may continue to output the incident beam at the target via an (adjustable) collimator assembly. For example, one or more light sources may generate the beam. The beam may be transmitted (e.g., via one or more input optical fibers) to the collimator assembly and, after passing through the optical components of the collimator assembly, may be guided onto the target. The target may be a calibration device, a reference substrate with known optical properties, or a conventional substrate about to undergo a process (e.g., etching), provided that the optical properties of such a substrate are known.

[0055] An incident light beam can cause the target material to produce a reflected beam. The reflected beam can pass (in the opposite direction) through the collimator's optical components and can be transmitted through one or more output optical fibers to a photodetector. At operation 830, the photodetector can determine the intensity of the reflected beam. At operation 840, a processing device communicating with the photodetector and a memory element can retrieve calibration data of the target material from the memory element. In some implementations, the calibration data may include the target material reflectivity, which varies with the incident angle of the light beam. At operation 850, method 800 may continue, with the processing device performing a comparison of the intensity data obtained from the photodetector with the calibration data retrieved from the memory element. Thus, the processing device can determine the degree of misalignment of the collimator assembly (e.g., attributable to a modified processing chamber setup). For example, reflectivity may decrease (or increase) with the degree of misalignment.

[0056] At operation 860, method 800 can output a tilt adjustment value, which will be applied to the tilt adjustment mechanism of the collimator assembly to correct the determined misalignment of the collimator assembly. A human operator can access the output value and correct the alignment of the collimator assembly based on the output value.

[0057] Figure 9 A block diagram depicts an example processing apparatus 900 operating according to one or more aspects of this disclosure. In one implementation, the processing apparatus 900 may be... Figure 1 Processing device 136. Example processing device 900 can be connected to other processing devices in a local area network, internal network, external network, and / or the Internet. Processing device 900 can be a personal computer (PC), set-top box (STB), server, network router, switch, or bridge, or any device capable of executing a set of instructions (sequentially or otherwise) specifying the actions to be taken by said device. Furthermore, although only a single example processing device is shown, the term "processing device" should also be understood to include any collection of processing devices (e.g., computers) that individually or jointly execute a set (or more) of instructions to perform any one or more methods discussed herein.

[0058] Example processing apparatus 900 may include a processor 902 (e.g., CPU) that can communicate with each other via bus 930, main memory 904 (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous dynamic random access memory (SDRAM), etc.), static memory 906 (e.g., flash memory, static random access memory, etc.), and auxiliary memory elements (e.g., data memory element 918).

[0059] Processor 902 represents one or more general-purpose processing devices, such as microprocessors, central processing units, etc. More specifically, processor 902 may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor implementing other instruction sets, or a processor implementing combinations of instruction sets. Processor 902 may also be one or more special-purpose processing devices, such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), network processors, etc. According to one or more aspects of this disclosure, processor 902 may be configured to execute instructions implementing method 700 for deploying a wideband collimator assembly for precise optical characterization of a target within a processing chamber and / or method 800 for adjusting the tilt of an adjustable collimator assembly.

[0060] The example processing device 900 may also include a network interface device 908 communicatively coupled to a network 920. The example processing device 900 may also include a visual display 910 (e.g., a liquid crystal display (LCD), a touchscreen, or a cathode ray tube (CRT)), an alphanumeric input device 912 (e.g., a keyboard), an input control device 914 (e.g., a cursor control device, a touchscreen control device, a mouse), and a signal generation device 916 (e.g., an acoustic speaker).

[0061] Data storage element 918 may include a computer-readable storage medium (or more specifically, a non-transient computer-readable storage medium) 928 on which one or more sets of executable instructions 922 are stored. According to one or more aspects of this disclosure, the executable instructions 922 may include executable instructions for implementing a method 700 of deploying a wideband collimator assembly for precise optical characterization of a target within a processing chamber, and / or a method 800 of adjusting the tilt of an adjustable collimator assembly.

[0062] During execution of the example processing apparatus 900, the executable instructions 922 may also reside wholly or at least partially in the main memory 904 and / or the processor 902, which together constitute a computer-readable storage medium. The executable instructions 922 may also be transmitted or received over a network via a network interface device 908.

[0063] Although computer-readable storage medium 928 is Figure 9 While referred to as a single medium, the term "computer-readable storage medium" should be understood to include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) storing one or more sets of operational instructions. The term "computer-readable storage medium" should also be understood to include any medium capable of storing or encoding a set of machine-executable instructions that cause the machine to perform any or more of the methods described herein. Therefore, the term "computer-readable storage medium" should be understood to include, but is not limited to, solid-state memories and optical and magnetic media.

[0064] It should be understood that the above description is intended to be illustrative and not limiting. Many other embodiments will become apparent to those skilled in the art upon reading and understanding the above description. Although specific examples have been described in this disclosure, it will be appreciated that the systems and methods of this disclosure are not limited to the examples described herein but can be practiced with modifications within the scope of the appended claims. Therefore, the specification and drawings are to be considered illustrative and not restrictive. Accordingly, the scope of this disclosure should be determined by reference to the full scope of the appended claims and their equivalents.

[0065] The methods, hardware, software, firmware, or code described above can be implemented by instructions or code stored on a machine-accessible, machine-readable, computer-accessible, or computer-readable medium executable by a processing element. "Memory" includes any mechanism that provides (i.e., stores and / or transmits) information in a machine-readable form, such as a computer or electronic system. For example, "memory" includes random-access memory (RAM), such as static random-access memory (SRAM) or dynamic random-access memory (DRAM); read-only memory; magnetic or optical storage media; flash memory devices; electrical storage devices; optical storage devices; acoustic storage devices; and any type of tangible machine-readable medium suitable for storing or transmitting electronic instructions or information in a machine-readable (e.g., computer) form.

[0066] Throughout this specification, the phrase "an implementation" or "implementation" means that a particular feature, structure, or characteristic described in connection with said implementation is included in at least one implementation of this disclosure. Therefore, the appearance of the phrase "in an implementation" or "in an implementation" throughout this specification does not necessarily refer to the same implementation. Furthermore, in one or more implementations, a particular feature, structure, or characteristic may be combined in any suitable manner.

[0067] In the foregoing specification, a detailed description has been given with reference to specific exemplary implementations. However, it will be apparent that various modifications and changes can be made thereto without departing from the broader spirit and scope of this disclosure as set forth in the appended claims. Therefore, the specification and drawings are to be considered illustrative rather than restrictive. Furthermore, the foregoing use of the terms "implementation," "implementation," and / or other exemplary language does not necessarily refer to the same implementation or the same example, but may refer to different and dissimilar implementations, and may also refer to the same implementation.

[0068] The terms “example” or “exemplary” are used herein to mean used as an example, instance, or illustration. Any aspect or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other aspects or designs. Rather, the use of the terms “example” or “exemplary” is intended to present concepts in a specific manner. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless otherwise stated or explicitly indicated by the context, “X comprises A or B” is intended to mean any natural inclusive substitution. That is, if X comprises A; X comprises B; or X comprises both A and B, then any of the foregoing satisfies “X comprises A or B.” Furthermore, the articles “a” and “an” used in this application and the appended claims should generally be construed as meaning “one or more” unless otherwise stated or explicitly indicated from the context in the singular form. Additionally, the use of the terms “implementation” or “an implementation” or “implementation” or “an implementation” does not imply the same implementation or realization unless so described in the specification. Furthermore, the terms “first,” “second,” “third,” “fourth,” etc., as used herein, are intended to distinguish different components, and their reference numerals do not necessarily have ordinal meaning.

Claims

1. A collimator assembly, comprising: Collimator housing, comprising: An interface configured to be coupled to a processing chamber; and A conduit for providing pathways for a first optical fiber and a second optical fiber to a housing formed by the collimator housing, wherein the first optical fiber is used to transmit multiple spectral components of light to the collimator housing; and An achromatic lens, at least partially located within the housing formed by the collimator housing, the achromatic lens being used for: Multiple spectral components of the light are directed onto a target surface disposed within the processing chamber.

2. The collimator assembly as claimed in claim 1, characterized in that, The multiple spectral components of the light include: A first set of spectral components within the wavelength range of 400-700 nm, wherein the first set of spectral components is used to irradiate a first region of the target surface, and A second set of spectral components outside the 400-700nm wavelength range, wherein the second set of spectral components is used to irradiate a second region of the target surface, wherein the overlap between the first region and the second region is at least 90% of each of the first region and the second region.

3. The collimator assembly as described in claim 2, characterized in that, The light has multiple spectral components that are at least 300 nm wide.

4. The collimator assembly as claimed in claim 1, characterized in that, The second optical fiber is used for: Collects multiple reflection spectral components of light generated from multiple spectral components of light guided to the target surface from the target surface; and Multiple reflection spectral components of the light are transmitted to a photodetector.

5. The collimator assembly of claim 4, further comprising an optical interface disposed between the port and the chromatic aberration lens, the optical interface being configured to allow light to pass through the housing while preventing the entry of contaminants from the processing chamber.

6. The collimator assembly as claimed in claim 1, characterized in that, The chromatic aberration lens is held in place by friction within the housing formed by the collimator housing.

7. The collimator assembly as claimed in claim 1, characterized in that, The chromatic aberration lens is a triple lens.

8. The collimator assembly as claimed in claim 1, characterized in that, Multiple spectral components of the light guided to the target surface by the chromatic lens form a collimated beam.

9. The collimator assembly of claim 1, further comprising an optically transparent filler filling at least a portion of the housing formed by the collimator housing.

10. The collimator assembly as claimed in claim 1, characterized in that, The collimator housing further includes a tilt adjustment mechanism to modify the alignment of the collimator housing's axis relative to the processing chamber.

11. The collimator assembly as claimed in claim 10, characterized in that, The tilt adjustment mechanism includes a plurality of adjusting screws, wherein adjusting each of the plurality of adjusting screws modifies the alignment of the axis of the collimator housing.

12. The collimator assembly of claim 10, further comprising a first support rigidly coupled to the collimator housing, a second support rigidly coupled to the processing chamber, and a gap between the first support and the second support, wherein the gap is configured to accommodate movement of the first support caused by a modified alignment of the axis of the collimator housing.

13. The collimator assembly of claim 12, further comprising one or more tension springs to stabilize the first support relative to the second support.

14. An endpoint detection system, comprising: A light source, used to output multiple spectral components of light; Collimator housing, comprising: An interface configured to be coupled to a processing chamber; and A conduit for providing pathways for a first optical fiber and a second optical fiber to a housing formed by the collimator housing, wherein the first optical fiber is used to transmit multiple spectral components of light to the collimator housing. An achromatic lens, at least partially located within the housing formed by the collimator housing, the achromatic lens being used for: Multiple spectral components of the light are directed onto a target surface disposed within the processing chamber; Multiple reflection spectral components of light are guided from the target surface to the second optical fiber, wherein the multiple reflection spectral components of light are generated by the spectral components of the multiple light guided to the target surface; A photodetector for receiving multiple reflection spectral components of the light via the second optical fiber; and A processing device communicatively coupled to the photodetector to determine one or more optical properties of the target surface using multiple reflection spectral components of the received light.

15. The endpoint detection system as described in claim 14, characterized in that, The multiple spectral components of the light include: A first set of spectral components within the wavelength range of 400-700 nm, wherein the first set of spectral components is used to irradiate a first region of the target surface, and A second set of spectral components outside the 400-700nm wavelength range, wherein the second set of spectral components is used to irradiate a second region of the target surface, wherein the overlap between the first region and the second region is at least 90% of each of the first region and the second region.

16. The endpoint detection system as described in claim 14, characterized in that, The chromatic aberration lens is held in place by friction within the housing formed by the collimator housing.

17. The endpoint detection system as described in claim 14, characterized in that, The chromatic aberration lens is a triple lens.

18. The endpoint detection system of claim 14, further comprising: A tilt adjustment mechanism is provided to modify the alignment of the collimator housing's axis relative to the processing chamber.

19. The endpoint detection system as described in claim 18, characterized in that, The tilt adjustment mechanism includes: A plurality of adjusting screws, wherein adjusting each of the plurality of adjusting screws modifies the alignment of the axis of the collimator housing; and One or more tension springs.

20. A method comprising the following steps: Multiple spectral components of light are transmitted to a housing formed by the collimator housing via a first optical fiber passing through a conduit in the collimator housing, wherein the conduit provides pathways for the first and second optical fibers to the housing formed by the collimator housing; Multiple spectral components of the light are guided onto the target surface located within the processing chamber using an achromatic lens. Multiple reflection spectral components of light generated by multiple spectral components of light guided to the target surface are collected from the target surface via the second optical fiber. Multiple reflection spectral components of the light are received by a photodetector via the second optical fiber; as well as A processing device communicatively coupled to the photodetector uses multiple reflection spectral components of the received light to determine one or more optical properties of the target surface.

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