Real-time detection of particulate matter during deposition chamber fabrication

Abstract

The disclosed embodiments describe a system comprising: a deposition chamber; a light source for generating an incident light beam, wherein the incident light beam is used to illuminate a region of the deposition chamber; and a camera for collecting scattered light originating from the illuminated region of the deposition chamber, wherein scattered light is generated when the first incident light beam interacts with particles within the illuminated region of the deposition chamber. The described system may optionally include a processing device coupled to the camera to generate scattering data at multiple locations within the illuminated region, wherein the scattering data at each location includes the intensity of the scattered light originating from that location.

Description

Technical Field

[0001] This specification generally relates to controlling and improving the quality of materials manufactured in a deposition chamber. More specifically, this specification relates to real-time detection of particulate matter in a deposition chamber without interrupting the manufacturing process occurring within the chamber. Background Technology

[0002] The fabrication of modern materials typically involves various deposition techniques, such as chemical vapor deposition (CVD) or physical vapor deposition (PVD), in which one or more selected types of atoms are deposited onto a substrate maintained in a low or high vacuum environment provided by a vacuum chamber. Materials manufactured in this way can include single crystals, semiconductor films, fine coatings, and many other substances used in practical applications. Many such applications critically depend on the purity of the grown material. Although the vacuum environment within the chamber significantly reduces the amount of contaminants present in the growth environment (e.g., contaminants present in the surrounding atmosphere), some contaminants can still find a way into the chamber. For example, impurities can be transported into the deposition chamber along with the flowing chemicals used in CVD or the sputtering (or evaporation) source used in PVD. Such impurities may be released into the environment of the deposition chamber and remain as defects in the material being manufactured. This can contaminate the material and adversely affect its morphology. Minimizing or otherwise controlling the amount of contaminants within the deposition chamber and preventing those contaminants still present in the chamber from reaching the substrate containing the material are key manufacturing challenges. Attached Figure Description

[0003] Figure 1 The diagram illustrates a system in an exemplary embodiment that performs real-time detection of particulate contaminants present in a deposition chamber based on light scattering data of the incident beam scattered by the contaminant.

[0004] Figure 2A This is a schematic diagram of a system in an exemplary embodiment that performs real-time detection of particulate contaminants present in a deposition chamber based on light scattering data. The system uses a rotating mirror to collimate the beam inside the deposition chamber.

[0005] Figure 2B This is a schematic diagram of a system in an exemplary embodiment that performs real-time detection of particulate contaminants present in a deposition chamber based on light scattering data. The system uses a lens to illuminate the interior of the deposition chamber with an extended beam of light.

[0006] Figure 3A This is a schematic diagram of a system in an exemplary embodiment that performs real-time detection of particulate contaminants present in a deposition chamber based on light scattering data. The system uses two light sources to achieve more uniform illumination of the deposition chamber.

[0007] Figure 3B This is a diagram illustrating the uniformity of illumination of a region within a deposition chamber using two beams in one exemplary embodiment, showing the relative intensity of light entering the deposition chamber as a function of position along the diameter of a circular window.

[0008] Figure 4 This is a schematic diagram of a system in an exemplary embodiment that performs real-time detection of particulate contaminants present in a deposition chamber based on light scattering data. The system uses a single light source and a beam splitter to achieve more uniform illumination within the deposition chamber.

[0009] Figure 5 This is a schematic diagram of a system in an exemplary embodiment that performs real-time detection of particulate contaminants present in a deposition chamber based on light scattering data, wherein a single light source is used in conjunction with a window that is relatively small in size compared to the deposition chamber.

[0010] Figure 6 This is a flowchart of a possible implementation of a method for real-time detection of particulate contaminants present in a deposition chamber based on light scattering data.

[0011] Figure 7 A block diagram of an example processing system is depicted, which supports real-time detection of particulate contaminants present in a deposition chamber based on light scattering data. Detailed Implementation

[0012] The embodiments disclosed herein allow for real-time detection of particulate matter, such as impurities or contaminants, within a deposition chamber without interrupting the fabrication deposition process (e.g., without opening and directly entering the deposition chamber). These embodiments can be performed during the fabrication deposition process. One or more light sources can transmit one or more light beams into the deposition chamber through one or more transparent windows. The light beams can interact with the particulate matter within the chamber and produce scattered light. The scattered light can exit from the chamber through some transparent windows and can be detected by a camera at these windows. The camera can be focused to observe a portion of the irradiated area inside the chamber. The camera can image the position of the particles within the chamber and can further generate machine-readable data (e.g., digital data) indicating the intensity of the scattered light with respect to various light sensors of the camera. The camera can provide the machine-readable data to a processing device (e.g., a computer) to generate light scattering data. The light scattering data can map the intensity of the scattered light to the actual physical location inside the camera based on camera parameters (e.g., the focal length of the camera lens, the distance from the camera lens to the chamber, etc.). The processing device can further determine the particle distribution within the irradiated area of ​​the deposition chamber based on the light scattering data. In some implementations, the processing apparatus is able to estimate the quality of the material grown in the deposition chamber based on the determined particle distribution and the stored calibration data.

[0013] The disclosed embodiments relate to a variety of manufacturing techniques using deposition chambers, such as chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma-enhanced CVD, plasma-enhanced PVD, sputtering deposition, atomic layer CVD, combustion CVD, catalytic CVD, evaporation deposition, molecular beam epitaxy, etc. While the disclosed embodiments are expected to have the most significant practical impact among techniques using vacuum deposition chambers (e.g., ultra-high vacuum CVD or PVD, low-pressure CVD, etc.), the same systems and methods can be used in atmospheric pressure deposition chambers for non-invasive monitoring of the chamber environment during the deposition process. In the following, the terms "deposition chamber" and "chamber" are used interchangeably to refer to any such chamber used in deposition fabrication, regardless of the vacuum conditions required by the specific technique used.

[0014] Contaminants present in the chamber can permeate into the chamber from the surrounding atmosphere along with chemicals injected into the chamber for actual deposition onto the wafer, chemicals used to generate the plasma environment, or as impurities in the ultrapure water used to clean the chamber components (e.g., during the preparation phase of manufacturing). During manufacturing, contaminants may be transported to the deposition area along with the chemical stream. Contaminants can adhere to the walls of processing modules and transport channels, acting as seed crystals (nucleation centers) for spurious in-situ growth. Subsequently, this in-situ growth may detach, "fall off," and enter the wafer material, becoming a defect within it.

[0015] Standard techniques for monitoring contaminants within deposition chambers involve preparing specialized "witness wafers" to probe the chamber environment at specific times. The witness wafer can be carefully prepared in an ultra-clean environment, and its surface can be inspected using a highly sensitive monitoring system. The witness wafer can then be inserted into the chamber to control deposition. Subsequently, the witness wafer can be inspected again, and the amount of contaminants deposited on its surface can be determined. Based on the amount and type of contaminant deposits, the conditions of the chamber environment can be inferred, and the quality of the manufacturing process's product yield can be estimated.

[0016] This quality control method, or similar methods, has many drawbacks. The processes of witness wafer preparation, insertion into the chamber, and subsequent testing are both time-consuming and expensive, thus wasting valuable resources. Such methods typically probe chamber conditions at specific times, rather than monitoring the chamber environment during actual product manufacturing. By their specific design, this invasive approach disrupts temperature dynamics and the flow of atoms and contaminants within the chamber, and does not operate under conditions suitable for actual operation. Therefore, the chamber environment during control deposition may differ significantly from the actual state of the chamber environment during manufacturing. Furthermore, the insertion and retrieval of witness wafers can introduce additional contaminants into the chamber. Even under ideal conditions, witness wafer methods have significant inherent limitations, such as the impossibility of real-time monitoring of contaminant location and their dynamics. The method provides very limited feedback on how and when contaminants enter the chamber environment and which setup adjustments will most effectively reduce the amount of contaminants near the wafer.

[0017] This disclosure addresses these and other limitations of existing methods. It discloses systems and methods for non-invasive, real-time intracavitary monitoring of contaminant concentration and dynamics using light scattering data collected through one or more windows of a chamber. The term "contaminant" can include impurities, such as particles (or clusters of particles) of the wrong chemical type. For example, during the manufacture of silicon solar cells, impurities can include iron, copper, molybdenum, or other metals that can significantly reduce solar cell efficiency to the point that solar cell production becomes economically unfeasible. The term "contaminant" can also include particles of the correct chemical type but of the wrong size or morphology. For example, silicon clusters that have not been properly broken down into atoms may end up deposited monolithically in a silicon chip, constituting a defect that adversely affects carrier mobility in the chip.

[0018] Figure 1 The diagram illustrates a system 100 in an exemplary embodiment, which performs real-time detection of particulate contaminants present in a deposition chamber based on light scattering data of the incident beam of contaminants. Figure 1 Intended as an illustration, Figure 1 Some of the components shown may be optional or can be replaced by other components with the same or similar functions. In one embodiment, system 100 may have a deposition chamber 102, such as a vacuum deposition chamber. The deposition chamber 102 may have a circular horizontal cross-section, such as... Figure 1As shown, it may have any other design known in the art. The deposition chamber 102 may be able to hold wafer 104 or multiple wafers (not shown) to support material growth on the wafers. The wafers may be placed horizontally (as shown by the solid line illustrating wafer 104) or vertically (as shown by the dashed line illustrating wafer 104), or in any other manner. In some embodiments, one or more wafers may be placed at an angle to a horizontal plane. Wafer 104 may be made of a semiconductor material (e.g., silicon), a dielectric (e.g., silicon oxide), or any other suitable material. Wafer 104 may be patterned or unpatterned. A gas flow (e.g., a chemical precursor used in deposition) and / or plasma (partially ionized gas with electrons and ions) may be present within the deposition chamber 102. In some embodiments, such as when the deposition chamber 102 is used with a sputtering deposition technique, the chamber 102 may contain a target (not shown), such as a sputtering target, which is bombarded by ionic particles (e.g., argon ions in one embodiment) to produce a jet of microparticles. The various flows within chamber 102 (e.g., precursors, plasma, flows of atoms / ions sputtered from the target) can be diffuse (when the gas / plasma density is high) or ballistic (when such density is low). In some embodiments, for example, when deposition of material is facilitated by gravity, wafer 104 may be located below the region of gas / plasma. In other embodiments, for example, when deposition is performed by sputtering, wafer 104 may be located above the region of gas / plasma. Other arrangements of wafer 104 are also possible, and the disclosed embodiments are fully applicable to all of these arrangements.

[0019] Gases and / or plasmas containing atoms and ions used in the deposition process can be delivered to the region of the deposition chamber 102 near the wafer 104. The gases / plasma may also deliver particles 106, such as contaminants, impurities, or any other potential defects that may ultimately deposit in the product of the deposition process. Particles 106 may be located above the wafer 104 (e.g., Figure 1 (As shown), below wafer 104, or at any other location relative to the wafer. To detect particles 106, during the operation of the manufacturing process within the deposition chamber 102, the light source 108 can guide an incident light beam into the interior region of the chamber 102 through one or more windows (e.g., side windows 110). The windows can be made of any transparent or translucent material. The location of the windows used to guide the light beam into the chamber can vary. Figure 1The location depicted is shown in the image. The side window may have a fixed size or an adjustable size. In some embodiments, the light beam generated by the light source 108 may be a coherent light beam, such as a laser beam. In other embodiments, the light source 108 may generate natural light, linear, circularly or elliptically polarized light, partially polarized light, focused light, etc. The light source 108 may generate a continuous light beam or multiple discrete pulse signals. The light source 108 may generate a collimated light beam, a focused light beam, or an extended light beam. In some embodiments, the light source 108 may generate a monochromatic light beam whose frequency / wavelength is within a narrow frequency / wavelength region located near a certain center frequency / wavelength. Alternatively, multiple monochromatic light beams may be used. In other embodiments, the light source 108 may generate a light beam with a broad spectral distribution, such as white light. In some embodiments, the light beam is in the visible portion of the spectrum. In some embodiments, the spectral distribution of the light beam may include infrared or ultraviolet frequencies that are undetectable by the human eye.

[0020] An incident light beam generated by light source 108 can illuminate an area of ​​deposition chamber 102. This illuminated area can be a portion of the chamber located at or near wafer 104, or it can be at a distance from wafer 104. In some embodiments, the illuminated area can be a cross-sectional slice of a portion of chamber 102 visible through side window 110. In some embodiments, the illuminated area can be a small portion of chamber 102, while in other embodiments, the illuminated area can be a large portion of chamber 102.

[0021] The incident light beam can interact with the particles 106 present in the irradiation area of ​​chamber 102 and produce scattered light. The term "scattered light" includes any electromagnetic radiation that can be caused by the incident light, such as electromagnetic radiation reflected from the surface of the particles 106 or radiation generated within the volume of the particles. The term "scattered light" includes electromagnetic radiation having the same frequency as the incident light, as well as electromagnetic radiation having a frequency that is higher (e.g., due to upconversion of photons) or lower (e.g., fluorescence) than the frequency of the incident light beam.

[0022] A certain amount of scattered light can escape from chamber 102 through one or more windows of the chamber. For example, in some embodiments, such as Figure 1As schematically depicted, scattered light can pass through a top window 114. The scattered light escaping through the window (e.g., top window 114) can be detected by camera 112. The term "camera" includes any digital, analog photographic, or video camera. The term "camera" also includes any other device capable of detecting light intensity, such as one or more (or any combination thereof) of a photoelectric emitting unit, a photovoltaic unit, a photosensor unit, a photochemical sensor (e.g., a photographic plate and film), a polarization sensor, a photodetector, a semiconductor sensor, a thermal detector of light, etc. For example, camera 112 may be a digital camera using a charge-coupled device (CCD) sensor. In another embodiment, camera 112 may be a digital camera using a complementary metal-oxide-semiconductor (CMOS) sensor.

[0023] Camera 112 may have one or more optical lenses. In principle, camera 112 can be operated by collecting photons of scattered light at its focal point from various locations within the camera's field of view. As disclosed in more detail below, the focal point of camera 112 can be changed / repositioned during particle detection. In some embodiments, particle 106 can be detected as a bright spot in scattering data (e.g., a digital image) generated by camera 112. In some embodiments, the scattering data may include an image of a Fraunhofer diffraction pattern surrounding a principal bright spot corresponding to the particle. In some embodiments, the particle size can be determined by measuring the ratio of the total amount of light generated by the particle (i.e., the total number of photons) to the intensity of the incident beam and further considering the particle's exposure to the incident beam. In some embodiments, the particle size can be further determined from the size of the Fraunhofer rings.

[0024] although Figure 1 The illustration shows an incident light beam entering the chamber through a window (e.g., side window 110) and being detected by a different window (e.g., top window 114), but in some embodiments, a single window can serve both purposes. In such embodiments, the incident light beam can be positioned to prevent direct reflection from the window surface to the camera 112. Additionally, an anti-reflective coating can be used to further prevent reflections / glare.

[0025] Camera 112 may be able to store captured images in analog or digital form. In some embodiments, camera 112 may be able to generate and store data files containing machine-readable data (e.g., digital data) indicating the intensity of scattered light from various light sensors of camera 112. Camera 112 may provide machine-readable data to processing device 116 to generate light scattering data. The light scattering data may map the intensity of scattered light to an actual physical location inside the camera based on camera parameters such as the focal length of the camera lens, the distance from the camera lens to the chamber, and similar parameters. For example, the scattering data may be an image of the intensity of scattered light, which is a function of two Cartesian coordinates (or two angles, polar angle and azimuth angle) within the field of view of camera 112 in the same field of view. The processing device may further determine the particle distribution within the irradiated area of ​​the deposition chamber based on the light scattering data. In some embodiments, camera 112 may be connected to computing device 116 via a wireless or wired network. In some embodiments, computing device 116 may be integrated into camera 112. In some embodiments, the processing device may be able to infer the quality of the material grown on the wafer 104 based on the distribution of the particles 106. For example, the computing device 116 may execute a software program that inputs scattering data from the memory of the camera 112 or from the memory of the computing device 116. The software program may determine the density of the particles 106 within the irradiation area of ​​the chamber 102. The particle density may refer to the number of particles per unit volume of the chamber or per unit cross-sectional area of ​​the chamber. In some embodiments, the software program may determine the volume density n(d) as a function of the distance d to the wafer based on the scattering data. To measure the particle density n(d), the camera may be continuously focused at different depths within the chamber 102. Additionally, for each increment of distance d, the light source 108 may be repositioned at the corresponding depth of the camera 112 to provide optimal imaging conditions for the camera 112. The software program may then access calibration data from the memory device and predict one or more parameters describing the quality of the material produced by the chamber 102 based on the calibration data. For example, parameters describing material quality may include the size, concentration, and type of defects present in the material.

[0026] The computing device 116 may be able to determine the size of the defect by measuring the total amount of light scattered by the particles. The computing device 116 may further be able to determine the type of material based on the scattering data. For example, the total amount of light scattered by the particles (e.g., total scattering cross section) and the angular distribution of the scattered light intensity (e.g., differential scattering cross section) can both indicate the material of the particles and their size. The computing device 116 may be able to predict the concentration of defects in the material by first counting the number of scattering centers in the scattering data generated by the camera 112 to determine the density n(d) of the particles 106. Calibration data can be obtained by correlating the observed particle density n(d) with the quality of the material obtained during a test (calibration) run, during which a variety of available techniques (such as scanning electron microscopy, tunneling electron microscopy, X-ray scattering, neutron scattering, etc.) can be used to measure the quality. The output of the calibration process can be a correspondence between scattering data (such as the number of scattering centers, the total intensity of scattering, and the angular correlation of scattering) and the predicted quality of the obtained material (including the type, size, and concentration of defects), such as a mathematical relationship (or a series of mathematical relationships), a graph (or a series of graphs), a table (or a series of tables), etc. In some implementations, calibration data can provide the accuracy range for quality prediction.

[0027] In some implementations... Figure 1 The system 100 illustrated in Figures 2a, 2b, 3a, 4, and 5 below can not only be used to determine the location of large particles constituting undesirable contaminants (e.g., particles whose size is many atomic dimensions), but also to map the density of atomic-sized particles intended for deposition. Larger contaminant particles can be imaged as bright spots in scattering data; unlike larger contaminant particles, atoms used in deposition may not be visible individually from scattering data. Instead, the density of atoms... It can be imaged as variations within a smooth background of scattered light. Atomic density can be determined based on the number of scattered photons detected originating from a specific point. The specific point is determined by its radius vector within the irradiation area of ​​chamber 102. This indicates that the density of atoms can be inferred from the intensity of the delocalized glow detected by camera 112. Its higher intensity corresponds to a higher atomic density. The atoms detected by this technique can include atoms of the active material intended to be deposited on wafer 104, as well as atoms of the auxiliary plasma, or any other atoms that can be injected into chamber 102. This imaging can be useful for determining the flow dynamics within the chamber. For example, it can determine how efficiently atoms of the deposited material are transported to the region near wafer 104, how consistent the atomic concentration is across the wafer length and width, the degree of ionization and uniformity of the plasma within the chamber, and so on.

[0028] Figure 2A This is a schematic diagram of system 200 in an exemplary embodiment, which performs real-time detection of particulate contaminants present in a deposition chamber based on light scattering data. System 200 uses a rotating mirror to collimate the beam inside the deposition chamber. Some components of system 200 may be the same as some components of system 100, as indicated by the corresponding matching numbers. As can be observed from the advantageous position of camera 112, Figure 2A A top view of the deposition chamber 102 is shown. Figure 2A In the illustrated embodiment, light source 108 (e.g., a laser) generates a narrow, collimated beam guided by rotating mirror 202 through side window 110 into chamber 102. The rotating mirror allows the collimated beam to scan an area of ​​chamber 102, such as the area below top window 114, while camera 112 captures images at an adjusted frame rate and shutter speed (e.g., adjusted by computing device 116), thus uniformly illuminating the entire field of view. For example, the frame rate can be set equal to the period of mirror rotation, and the shutter speed can be set equal to the duration of the beam within the field of view of camera 112. In some embodiments, the scanning speed (e.g., the angular velocity of the mirror) can be kept constant across the field of view during each beam stripe, so that particles of equal size (and located at the same distance from the mirror) are illuminated for an equal amount of time. Therefore, particles of equal size receive an equal amount of light and produce an equal amount of scattered light. This improves the consistency of particle detection and the accuracy of particle size determination.

[0029] Figure 2B This is a schematic diagram of a system 250 in an exemplary embodiment, which performs real-time detection of particulate contaminants present in a deposition chamber based on light scattering data. The system 250 uses a lens to illuminate the interior of the deposition chamber with an extended beam of light. Figure 2B In the illustrated embodiments, uniform illumination of the field of view of camera 112 can be achieved without moving any components. For example, a collimated beam generated by light source 108 can pass through lens 204 to produce an extended beam. In some embodiments, the beam extension angle can be large enough to illuminate the entire field of view of camera 112, such as the area visible through top window 114, or a portion of the visible area at the focal point of camera 112. In some embodiments, lens 204 can be cylindrical, such that the beam extends in one direction (e.g., horizontally as shown) but remains collimated in another direction (e.g., vertically) and illuminates a narrow slice of chamber 102. This can have the advantage of uniformly illuminating points inside the chamber that are at the same or nearly the same distance from camera 112, so that all (or most) of these points are simultaneously at the focal point of camera 112.

[0030] Although the instantaneous amount of light incident on any particle residing in the irradiated area (e.g., the number of photons per unit time) is substantially less than Figure 2A The amount of light in the rotation setting, but in both embodiments, when the collimated beam is pointed directly at the particle, the average total amount of light on a beam strip can be the same or similar. In some embodiments, Figure 2B The extended beam setup is preferred because it eliminates the need for moving parts or complex synchronization schemes to synchronize image acquisition by camera 112 with the position of mirror 202. In other cases, Figure 2A The rotating mirror setting can actually be advantageous.

[0031] The illumination plane can be adjusted between consecutive measurements by adjusting the height of the light source 108. For example, for each position of the light source 108, the beam generated by the light source 108 and the lens 204 can illuminate a first (e.g., planar) sub-region of the field of view of the deposition chamber 102, and the detection of particles 106 can be performed as described above. Subsequently, the beam can be repositioned by moving the light source 108 in a vertical direction (up or down) so that the beam illuminates a second sub-region of the field of view. In some embodiments, the camera 112 can be moved together with the light source 108 so that the new illumination sub-region remains in focus. For example, the camera can be mounted in a manner that keeps the camera rigidly connected to the light source. In other embodiments, the camera 112 can be kept fixed relative to the chamber 102 while adjusting the focal length of the camera to bring the new sub-region into focus. The vertical offset between two consecutive readjustments can be less than the vertical extension of the beam in the vertical direction (e.g., 1 mm in one embodiment), thereby ultimately covering the entire vertical extension of the visible area. In some embodiments, the repositioning of the beam is performed in a horizontal (or any other) direction rather than in the vertical direction.

[0032] In some embodiments, lens 204 may be a converging lens, such that after passing through the lens, the light beam first passes through the real focal point before expanding, such as... Figure 2B The image is schematically shown. However, in other embodiments, lens 204 may be a diverging lens with an imaginary focal point, such that the light beam expands immediately after passing through lens 204. In some embodiments, lens 204 may be a composite lens made of multiple lenses. Some or all of the lenses may be designed to reduce chromatic aberration and / or optical aberrations. In some embodiments, where beam uniformity is not necessary, such as when the illumination area is not very large, lens 204 may be a spherical lens.

[0033] Figure 3AThis is a schematic diagram of a system 300 in an exemplary embodiment, which performs real-time detection of particulate contaminants present in a deposition chamber based on light scattering data. The system 300 uses two light sources to achieve more uniform illumination within the deposition chamber. Both systems 200 and 250 shown in Figures 2a and 2b, respectively, may have the drawback of insufficient uniformity of illumination on the target area (e.g., the visible area within the chamber below the top window 114). More specifically, while uniformity of illumination can be good in the direction perpendicular to the system's optical axis, it is less uniform along the optical axis (e.g., along the top window 114). Figure 3A The uniformity of the x-axis (in the image) may be significantly low. This occurs because, for a cylindrically extended beam, the intensity of the light decreases inversely with the distance from the center of the beam (e.g., the focal point of a lens). Figure 3A This configuration can significantly improve illumination uniformity. In addition to the first light source 108 and the first lens 204, the system 300 may include a second light source 306 and a second lens 308 to provide a second extended beam. The second beam can be delivered into the deposition chamber 102 through the second side window 310. Figure 3A As shown, maximum illumination uniformity can be achieved if the two beams are guided from opposite sides of chamber 102 at an angle of 180°, but angles less than 180° can still substantially improve uniformity, albeit to a lesser extent.

[0034] To illustrate Figure 3A The dual-beam setup improves illumination uniformity to the extent that point A within the illumination area of ​​chamber 102 is considered. The first beam has a center at point B, and the second beam has a center at point C. An illustrative example of a circular top window 114 with radius a is shown, where the x-axis is chosen to have an origin (x = 0) at the center of the top window. Ignoring minor deviations of line AB from the system optical axis, the intensity of the first beam at point A is...

[0035]

[0036] Here, d is the distance from the origin x = 0 to the center of beam B, and β is a coefficient proportional to the total power of the beam. Similarly,

[0037]

[0038] This is the intensity of the second beam at point A. Correspondingly, the total intensity of the two beams at point A is...

[0039]

[0040] The uniformity of illumination can be estimated as the ratio of the minimum intensity to the maximum intensity within the field of view:

[0041]

[0042] The closer the value U is to 1, the more uniform the illumination. Conversely, a value U close to 0 but not close to 1 indicates highly non-uniform illumination. In the dual-beam setup, minimum irradiance (within the top window 114) is achieved at x = 0, while maximum irradiance is found at x = a (and x = -a). Therefore, the uniformity of dual-beam illumination is [value missing].

[0043]

[0044] Conversely, for single-beam illumination (e.g., only the first beam), the minimum value is located at the point farthest from the beam center B (x = a), and the maximum value is located at the point closest to the beam center (x = -a):

[0045]

[0046] This indicates that the improvement in illumination uniformity achievable in a dual-beam setup compared to a single-beam setup is:

[0047]

[0048] In particular, for a≈d / 3 (roughly corresponding to...) Figure 3A In one exemplary embodiment, the uniformity improvement is approximately 1.8; this improvement becomes more significant as the radius a of the visible area increases.

[0049] Figure 3B This is a diagram illustrating the uniformity of illumination of a region within a deposition chamber using two light beams in one exemplary embodiment, showing the relative intensity of light entering the deposition chamber as a function of position along the diameter of a circular window. Reference Figure 3A The symbols in the graph, curve 350, show the total illumination intensity as a function of position x+a. Each curve shown in curve 350 illustrates the intensity variation along different lines parallel to the x-axis within the top window 114, as indicated by the dashed lines within the top window 114. Figure 3B (The bottom of the curve). The curves shown in graph 350 have different lengths because the lengths of the corresponding dashed lines vary with their position relative to the axis of the system (i.e., with distance to the x-axis), with the outer dashed lines being shorter than the inner lines. In this illustrative example, the diameter of the field of view is 2a = 240 mm, and the distance from the center of beam B to the field of view is da = 100 mm. Although there is still some variation in the total intensity, for this particular illustration, the variation does not exceed 30%.

[0050] Even with only one light source deployed, the benefits of a two-beam setup can be taken advantage of. Figure 4This is a schematic diagram of a system 400 in an exemplary embodiment, which performs real-time detection of particulate contaminants present in a deposition chamber based on light scattering data. The system 400 uses a single light source and a beam splitter to achieve more uniform illumination within the deposition chamber. The system 400 has a single light source 108 and a beam splitter 412. The beam splitter 412 can redirect a portion (e.g., half) of the light beam generated by the light source 108. The redirected light beam can be further redirected by the system through mirrors (such as mirrors 414(1)-(3)) and enters the chamber 102 through a second lens 308 and a second side window 310. In the illustrated embodiment, three mirrors 414 are used. In other embodiments, the number of mirrors may be greater than or less than three. For example, two mirrors may be sufficient to deliver the separated light beam to a second lens 308, which spans the chamber and is directly opposite the first lens 204.

[0051] Figure 5 This is a schematic diagram of a system 500 in an exemplary embodiment, which performs real-time detection of particulate contaminants present in a deposition chamber based on light scattering data, wherein a single light source is used in conjunction with a window that is relatively small in size to the deposition chamber. Following previous estimates of illumination uniformity U, in these embodiments where the transparent window size is small (a << d), uniformity U is close to 1. In this case, the beam range is relatively small and illuminating the field of view with only one light source may be sufficient. Monitoring the chamber environment through a small window can be appropriately performed in those cases where the concentration of contaminants is sufficiently uniform throughout the chamber 102.

[0052] Figure 6 This is a flowchart of a possible implementation of a method 600 for real-time detection of particulate contaminants present in a deposition chamber based on light scattering data. It can be used... Figure 1Method 600 may be performed using the systems and components shown in 2a, 2b, 3a, 4, or 5, or some combination thereof. Method 600 may be performed using a single light source that produces a single beam, or using a single light source and one or more beam splitters that produce more than one beam, or using multiple light sources. In some embodiments, some or all blocks of method 600 may be performed in response to instructions from a computing device such as computing device 116. Computing device 116 may have one or more processing devices (e.g., central processing units) coupled to one or more memory devices. In one embodiment, method 600 may be performed during a manufacturing process occurring within a chamber, such as a process of depositing atoms on a wafer surface. In some embodiments, only one type of material is deposited, while in other embodiments, multiple different types of materials may be deposited. In some embodiments, the manufacturing process may involve more than one wafer. The manufacturing process may occur at low temperatures, or at temperatures below or significantly below room temperature. Alternatively, the manufacturing process may occur at room temperature, above room temperature, or significantly above room temperature. In some embodiments, the pressure within the chamber may be less than or significantly less than atmospheric pressure, including low or high vacuum conditions. In some implementations, method 600 can be performed without interrupting the manufacturing process.

[0053] Method 600 may include irradiating a region (610) of a deposition chamber with an incident light beam. The irradiated region may be adjacent to the wafer. The irradiated region may be separated from the wafer by a certain distance. The irradiated region may be in a portion of the chamber different from the portion including the wafer. The irradiated region of the chamber may include one or more sub-regions. For example, a given sub-region may be a narrow planar slice of the irradiated region. The sub-region may be located in a horizontal plane, a vertical plane, or any other plane intersecting the interior of the deposition chamber. Irradiation of the entire region of the deposition chamber may be performed by irradiating a first sub-region with an incident light beam, collecting light scattering data of the first sub-region (as illustrated in box 620 below), repositioning the incident light beam to irradiate a second sub-region, collecting light scattering data of the second sub-region, etc. Irradiation may be performed using a light beam generated by a single light source or multiple light sources. Irradiation may be performed using a focused beam, a collimated beam, a broadened beam, or any combination thereof. One or more light beams may enter the deposition chamber through one or more transparent or translucent windows of the chamber.

[0054] Method 600 may continue by collecting light scattering data (620) by detecting the intensity of scattered light originating from the irradiated area of ​​the deposition chamber. Scattered light may escape from the chamber through one or more windows, which may be the same as or different from the windows through which one or more incident light beams enter the chamber. Collecting light scattering data may include using any device or material sensitive to light intensity to detect the intensity of the scattered light. In some embodiments, a digital or analog camera with one or more lenses may be used to perform the collection of light scattering data, the lenses focusing the scattered light onto an array of light sensors, such as those of the camera. Each light sensor may correspond to a small area within the irradiated area of ​​the chamber, within the camera's field of view. Depending on the intensity of the scattered light reaching a particular light sensor (e.g., a pixel), the light sensor may generate an analog signal (such as a current signal or a voltage signal) such that the magnitude of the signal represents the intensity of the scattered light. The analog signal may be input to an analog-to-digital converter (ADC), which outputs a digital value corresponding to the intensity of the scattered light reaching the light sensor. This digital value may be stored in a memory device along with a symbol representing the pixel location. The memory device can be a camera's memory device or a memory device communicatively coupled to a computing device (e.g., computing device 116) of the camera. As a result, the memory device can store a digital mapping of the intensity of scattered light to the camera's light sensor array. The computing device can then generate light scattering data by associating each or some of the camera's light sensors with a corresponding location in the camera's field of view within the illumination area of ​​the chamber. Therefore, the light scattering data can include a correspondence between the intensity of the scattered light and the location of the origin of the scattered light within the illumination area.

[0055] Method 600 can continue to determine the particle distribution within the irradiated area of ​​the deposition chamber based on light scattering data (630). To determine the particle distribution, light scattering data (e.g., by a computing device) can be analyzed to extract features corresponding to the particles within the deposition chamber in the intensity of the scattered light. For example, these particles can be identified as local bright spots in the light scattering data, or by characteristic diffraction patterns near major maximum or minimum values ​​of intensity. The identified particle locations can be stored in a memory device. In some embodiments, estimates of the particle size and / or chemical type can be stored along with their locations. In some embodiments, the particle distribution includes the locations of all identified particles. This can be done, for example, when the identified particles are large clusters of many atoms. In some embodiments, as disclosed above, the particles are atomically sized particles whose individual locations cannot be determined. In such embodiments, the computing device may be able to determine the density (e.g., bulk density – number of atoms per unit volume) of such particles by analyzing a smoothed background of the intensity of the scattered light. In such embodiments, determining the particle distribution may include mapping the particle density onto the irradiated area of ​​the chamber.

[0056] In some implementations, method 600 may continue to estimate the quality of material grown on the wafer in the deposition chamber based on the particle distribution within the irradiation area of ​​the deposition chamber (640). This can be accomplished by comparing the particle distribution determined by the computing device with calibration data stored in the memory device of the computing device or in any other storage location accessible to the computing device (e.g., in the cloud).

[0057] The systems and methods disclosed herein can be used to directly measure the location, density, and dynamics of contaminant particles during runtime in wafer processing. The systems and methods disclosed herein can have very high sensitivity, limited only by the observation time (e.g., exposure time) of the irradiated chamber and / or by the velocity of the particles within the chamber. The systems and methods disclosed herein can be used not only for quality monitoring during manufacturing but also for testing and development of various deposition chamber designs. Advantages of the disclosed implementations include, but are not limited to: the ability to map critical regions of the chamber at different distances from the wafer; near-instantaneous feedback during runtime processing within the chamber; the absence of long and costly pretreatment; and the ability to implement chamber modifications during processing and measure the resulting changes in the chamber environment and particle dynamics.

[0058] Figure 7 A block diagram depicts an example processing apparatus 700 operating according to one or more aspects of this disclosure. In one embodiment, the processing apparatus 700 may be... Figure 1 The computing device 116.

[0059] The example processing device 700 can be connected to other processing devices in a LAN, intranet, extranet, and / or the Internet. The processing device 700 can be a personal computer (PC), a set-top box (STB), a server, a network router, a switch, or a bridge, or any device capable of executing a set of instructions (sequentially or otherwise) specifying the actions the device should perform. Furthermore, although only a single example processing device is shown, the term "processing device" should also be considered to include any collection of processing devices (e.g., computers) that individually or collectively execute a set (or more) of instructions to perform any or more methods discussed herein.

[0060] Example processing device 700 may include processor 702 (e.g., CPU), main memory 704 (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) (such as synchronous DRAM (SDRAM)) etc.), static memory 706 (e.g., flash memory, static random access memory (SRAM) etc.) and auxiliary memory (e.g., data storage device 718), which can communicate with each other via bus 730.

[0061] Processor 702 represents one or more general-purpose processing devices, such as a microprocessor, central processing unit, or similar device. More specifically, processor 702 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 a combination of instruction sets. Processor 702 may also be one or more special-purpose processing devices, such as an Application-Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), a Digital Signal Processor (DSP), a Network Processor, or similar device. According to one or more aspects of this disclosure, processor 702 may be configured to execute instructions for implementing method 600, which detects particulate contaminants present in a deposition chamber in real time based on light scattering data.

[0062] The example processing device 700 may further include a network interface device 708, which can be communicatively coupled to the network 720. The example processing device 700 may further include a video display 710 (e.g., a liquid crystal display (LCD), a touch screen, or a cathode ray tube (CRT)), an alphanumeric input device 712 (e.g., a keyboard), an input control device 714 (e.g., a cursor control device, a touch screen control device, a mouse), and a signal generation device 716 (e.g., an acoustic speaker).

[0063] Data storage device 718 may include computer-readable storage medium (or more specifically, non-transitory computer-readable storage medium) 728 on which one or more sets of executable instructions 722 are stored. According to one or more aspects of this disclosure, the executable instructions 722 may include executable instructions for implementing method 600, which detects particulate contaminants present in a deposition chamber in real time based on light scattering data.

[0064] During the execution of the executable instructions 722 by the example processing device 700, the executable instructions 722 may also reside wholly or at least partially in the main memory 704 and / or the processor 702, which also constitute a computer-readable storage medium. The executable instructions 722 may further be transmitted or received over a network via a network interface device 708.

[0065] although Figure 7The computer-readable storage medium 728 shown herein is a single medium; however, the term "computer-readable storage medium" should be considered to include a single medium or multiple media (e.g., a centralized or distributed database and / or associated caches and servers) that store one or more sets of operational instructions. The term "computer-readable storage medium" should also be considered to include any medium capable of storing or encoding a set of instructions for machine execution, which causes the machine to perform any one or more methods described herein. Therefore, the term "computer-readable storage medium" should be considered to include, but is not limited to, solid-state storage as well as optical and magnetic media.

[0066] It should be understood that the above description is intended to be illustrative rather than limiting. Many other embodiments will become apparent to those skilled in the art upon reading and understanding the above description. Although specific examples are 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 should be considered illustrative rather than limiting. Consequently, the scope of this disclosure should be determined by reference to the appended claims and the full scope of their equivalents.

[0067] The methods, hardware, software, firmware, or code described above can be implemented via instructions or code stored on a machine-accessible, machine-readable, computer-accessible, or computer-readable medium executable by a processing element. "Memory" includes any structure 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 RAM (SRAM) or dynamic RAM (DRAM)); ROM; 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.

[0068] Throughout this specification, the reference to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of this disclosure. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0069] In the foregoing description, specific exemplary embodiments have been given in detail. However, it will be apparent that various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. Therefore, the description and drawings should be considered illustrative rather than restrictive. Furthermore, the foregoing use of terms such as embodiments, implementations, and / or other exemplary language does not necessarily refer to the same implementation or the same example, but may refer to different and distinct implementations as well as potentially identical implementations.

[0070] The terms “example” or “exemplary” are used herein to mean as an example, illustration, or description. Any aspect or design described herein as “example” or “exemplary” is not necessarily to be construed as being more preferred or advantageous than 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 clearly apparent from the context, “X comprises A or B” is intended to mean any natural inclusion arrangement. That is, if X comprises A; X comprises B; or X comprises A and B, then “X comprises A or B” is satisfied in any of the foregoing cases. Furthermore, the article “a” as used in this application and the appended claims should generally be interpreted as meaning “one or more” unless otherwise stated or clearly apparent from the context to the singular form. Additionally, the use of the terms “an embodiment” or “one implementation” or “one mode” throughout the document does not imply the same embodiment or implementation unless such a description is given. In addition, the terms “first,” “second,” “third,” “fourth,” etc., used in this article refer to labels used to distinguish different components, and do not necessarily have ordinal meanings based on their numerical names.

Claims

1. A method comprising: Irradiate the area of ​​the deposition chamber with the incident light beam; Light scattering data is collected using a photodetector by detecting the intensity of scattered light originating from an irradiated area of ​​the deposition chamber, wherein the scattered light is generated when the incident beam interacts with particles within the irradiated area of ​​the deposition chamber, wherein the detected intensity includes the intensity of the scattered light at an angle to the direction of the incident beam, and wherein the step of collecting the light scattering data includes: Changing the focus of the photodetector to each of a plurality of depths within the irradiation area of ​​the deposition chamber, wherein the step of changing the focus of the photodetector includes changing at least one of the following: The focal length of the photodetector, or The distance from the lens of the photodetector to the irradiated area of ​​the deposition chamber; and Collect multiple subsets of the light scattering data, wherein each subset of the multiple subsets of the light scattering data is associated with a corresponding depth among multiple depths within the irradiation area of ​​the deposition chamber; as well as Based on the light scattering data, the distribution of particles within the irradiation area of ​​the deposition chamber is determined.

2. The method of claim 1, wherein the distribution of the particles within the irradiation area of ​​the deposition chamber is represented by the positions of one or more of the particles.

3. The method of claim 1, wherein the distribution of the particles in the irradiation area of ​​the deposition chamber is represented by the density of the particles at one or more locations within the irradiation area of ​​the deposition chamber.

4. The method according to claim 1, wherein the incident beam is generated by a laser source.

5. The method of claim 1, wherein the incident beam is reflected by the rotating mirror.

6. The method of claim 1, wherein the incident light beam illuminating the region of the deposition chamber is passed through a cylindrical lens.

7. The method of claim 1, wherein detecting the intensity of the scattered light comprises: At least a portion of the scattered light is collected using a camera.

8. The method of claim 1, wherein the incident light beam passes through a first window of the deposition chamber, and wherein detecting the intensity of the scattered light comprises: At least a portion of the scattered light exiting the deposition chamber through the second window of the deposition chamber is collected.

9. The method of claim 1, wherein the region of the deposition chamber irradiated comprises: The incident beam illuminates a first sub-region of the region of the deposition chamber; The incident beam is repositioned to a second sub-region of the region of the deposition chamber; and The second sub-region of the region of the deposition chamber is illuminated by the incident beam.

10. The method of claim 1, wherein a process is performed within the deposition chamber to grow material on a wafer, the method further comprising: The quality of the material grown on the wafer in the deposition chamber is estimated based on the distribution of the particles within the irradiation area of ​​the deposition chamber.

11. A method comprising: The area of ​​the deposition chamber is illuminated by the first incident beam; The region of the deposition chamber is irradiated with a second incident beam, wherein the positioning of the second incident beam improves the uniformity of irradiation of the region compared to the uniformity of irradiation of at least a portion of the region by the first incident beam. Light scattering data is collected by detecting the intensity of scattered light generated by one or more particles within the irradiation area of ​​the deposition chamber, wherein at least a portion of the scattered light is generated by a subset of the one or more particles, each particle in the subset being simultaneously irradiated by both the first incident beam and the second incident beam, and wherein the detected intensity includes the intensity of the scattered light at an angle to the directions of the first incident beam and the second incident beam; and Based on the light scattering data, the distribution of the particles within the irradiation area of ​​the deposition chamber is determined.

12. The method of claim 11, wherein the first incident beam is generated by a first laser source and the second incident beam is generated by a second laser source.

13. The method of claim 11, wherein the first incident beam is extended by a first cylindrical lens, and the second incident beam is extended by a second cylindrical lens.

14. The method of claim 11, further comprising estimating the quality of material grown in the deposition chamber based on the distribution of the particles within the irradiation area of ​​the deposition chamber.

15. A system comprising: Deposition chamber; A first light source is used to generate a first incident beam, wherein the first incident beam is used to illuminate a region of the deposition chamber; and Camera, the camera being used for: Scattered light originating from an irradiation region of the deposition chamber is collected, wherein scattered light is generated when the first incident beam interacts with particles within the irradiation region of the deposition chamber, wherein the camera is configured to change its focus to each of a plurality of depths within the irradiation region of the deposition chamber to collect the scattered light, wherein changing the focus of the camera includes changing at least one of the following: The focal length of the camera, or The distance from the camera lens to the irradiation area of ​​the deposition chamber; and A processing device coupled to the camera to generate multiple subsets of light scattering data, wherein each subset of the multiple subsets of light scattering data is associated with a corresponding depth among multiple depths within the illumination area of ​​the deposition chamber, and wherein the light scattering data at each depth includes the intensity of the scattered light originating from that depth.

16. The system of claim 15, further comprising a second light source that generates a second incident beam, wherein the second incident beam is positioned to improve the uniformity of illumination of the portion of the irradiated region compared to the uniformity of illumination of at least a portion of the region by the first incident beam.

17. The system of claim 16, wherein, in order to improve the uniformity of irradiation of at least a portion of the irradiation area, the second incident beam enters the deposition chamber from a different side of the deposition chamber compared to the first incident beam.

18. The system of claim 16, wherein the first light source is a first laser source and the second light source is a second laser source.

19. The system of claim 15, further comprising a beam splitter to generate a second incident beam by redirecting a portion of the first incident beam, wherein the second incident beam is used to improve the uniformity of illumination of the portion of the region compared to the uniformity of illumination of at least a portion of the region by the first incident beam.

20. The system of claim 15, further comprising a cylindrical lens to extend the first incident beam.

21. The system of claim 15, wherein the processing apparatus further determines the distribution of particles in the irradiation area of ​​the deposition chamber based on the light scattering data, including the intensity of the scattered light.

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