CN116008234A - Reflectivity optical measurement device - Google Patents
Reflectivity optical measurement device Download PDFInfo
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- CN116008234A CN116008234A CN202211625238.4A CN202211625238A CN116008234A CN 116008234 A CN116008234 A CN 116008234A CN 202211625238 A CN202211625238 A CN 202211625238A CN 116008234 A CN116008234 A CN 116008234A
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Abstract
The invention discloses a reflectivity optical measurement device, which is arranged outside a reaction chamber and comprises: a light emitting module and a light detecting module; the light emitting module is used for emitting incident detection light, the light emitting module comprises a light emitting surface for emitting the incident detection light, the incident detection light is non-parallel light, and at least part of the incident detection light is projected onto a surface to be detected of an object to be detected in the reaction chamber through an observation port on the reaction chamber and is reflected by the surface to be detected; the light detection module is used for receiving emergent detection light reflected by the detected surface and emitted through the observation port. According to the invention, the light emitting module with the light emitting surface emits non-parallel light as incident detection light, so that effective measurement of reflectivity can be provided, the light path adjustment can be simpler, and the measuring device can be free from excessive limitation of the mounting position, thereby achieving the purposes of simplifying the light path and increasing the reliability, being applicable to measurement of epitaxial wafers with larger warpage and widening application scenes.
Description
Technical Field
The invention relates to the technical field of semiconductor device manufacturing, in particular to a reflectivity optical measurement device.
Background
In the manufacturing process of semiconductor devices, the growth temperature of epitaxial wafers is a key parameter for controlling the growth of thin films. Because the reaction conditions of the film growth reaction chamber are strict, the growth temperature of the epitaxial wafer must be measured by a non-contact temperature measurement method.
The non-contact temperature measurement method applied in the prior art adopts a high temperature measurement method corrected by thermal emissivity, and calculates the temperature of the surface of the epitaxial wafer by measuring the radiant light of a certain wave band and the emissivity of the surface of the corresponding epitaxial wafer. It is therefore necessary to obtain information on the emissivity by measuring the reflectivity by means of an optical measurement system.
Typically, an observation port is provided at the top of the reaction chamber, through which the optical measurement system emits a probe beam to the epitaxial wafer. The reflected light beam formed by the reflected light beam on the surface of the epitaxial wafer is detected by a detector, so that the reflectivity is obtained. The calculation control unit can calculate the reflectivity R of the epitaxial wafer surface at the position where the reflection occurs according to the detected intensity of the reflected light beam and the known intensity of the incident light, and calculate the emissivity epsilon of the epitaxial wafer according to an epsilon=1-R formula, so that the temperature of the epitaxial wafer surface can be calculated according to the emissivity epsilon of the epitaxial wafer surface.
The position and size of the viewing port are severely limited due to the special configuration of the epitaxial reaction chamber. However, the parallel light beam (such as a narrower parallel light beam emitted by a laser) used in the conventional optical measurement system needs to pass through a complex optical path to make the parallel collimated laser converge into a narrower incident laser beam, then pass through an observation port on the top of the reaction chamber (i.e. the size of the incident light beam at the observation port needs to be smaller than that of the observation port), vertically cast onto the epitaxial wafer, and reflect on the surface of the epitaxial wafer.
In addition, the conventional optical measurement system is limited by the installation position of the light source (for example, a spectroscope is required), so that good matching between the light source and the observation port is still difficult to achieve, the measurement system is difficult to install in the debugging process, and subsequent maintenance is also complicated. Once the mounting is shifted, the reflected light signal cannot be detected, so that the stability of temperature measurement is affected, and the growth temperature measurement of the epitaxial wafer cannot be guaranteed to be consistent and accurate.
Meanwhile, in the film growth process, the epitaxial wafer is warped due to the action of stress, and partial reflected light beams are deflected in angle and cannot exit through the observation port, so that the detector cannot receive the light beams. When the warping and the inclination are obvious, the problem that no optical signal is reflected into the detector can still occur due to the fact that the laser emits parallel light even if the emitting surface of the laser is infinitely large, namely, when parallel light detection is adopted, the problem that the reflectivity is difficult to accurately obtain through measurement easily occurs due to the influence of factors such as the surface state of an object to be detected and the like.
Accordingly, there is a need to provide a new optical measurement technique for reflectivity to solve the above-mentioned problems in the prior art.
Disclosure of Invention
The object of the present invention is to overcome the above-mentioned drawbacks of the prior art and to provide an optical measurement device for reflectivity.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
the invention provides a reflectivity optical measurement device, which is arranged outside a reaction chamber and comprises: a light emitting module and a light detecting module;
the light emitting module is used for emitting incident detection light, the light emitting module comprises a light emitting surface for emitting the incident detection light, the incident detection light is non-parallel light, and at least part of the incident detection light is projected onto a tested surface of an object to be tested in the reaction chamber through an observation port on the reaction chamber and is reflected by the tested surface;
the light detection module is used for receiving emergent detection light reflected by the detected surface and emitted through the observation port.
Further, the intensity of the incident detection light emitted from each place on the light emitting surface is uniformly distributed in a solid angle in the normal direction of the light emitting surface, and the intensity distribution in each solid angle is uniform; and defining half of the opening angle of the solid angle in any direction as beta, wherein beta is larger than or equal to the half vertex angle alpha of a cone formed between the projection of the center of the observation port on the plane of the object to be detected and the observation port.
Further, the size A of the light emitting surface and the size B of the observation port satisfy the following conditions:
A/B≥H/h
and H is the distance from the light emitting surface to the plane of the object to be detected, and H is the distance from the observation port to the plane of the object to be detected.
Further, the size A of the light emitting surface and the size B of the observation port satisfy the following conditions: H/H is less than or equal to A/B is less than or equal to 2H/H.
Further, the light emitting module comprises a surface light source, the surface light source forms a light emitting surface of the incident detection light, the surface light source is arranged facing the observation port, a receiving hole penetrating through the surface is formed in the surface light source, the light detecting module receives the emergent detection light reflected by the detected surface and emitted by the observation port through the receiving hole, and the receiving hole, the light detecting module and the observation port are arranged in a center alignment mode.
Further, the light emitting module includes: a surface light source and a first lens;
the surface light source emits the incident detection light;
the first lens is positioned between the surface light source and the observation port and is used for transmitting and condensing the incident detection light from the surface light source, an image of the surface light source is formed at a position between the first lens and the observation port, and the image of the surface light source forms a light emitting surface of the incident detection light;
the surface light source is provided with a receiving hole penetrating through the surface, the light detection module receives the emergent detection light reflected by the detected surface and emitted by the observation port through the receiving hole, and the receiving hole, the light detection module and the observation port are arranged in a center alignment mode.
Further, the surface light source image is located at the position of the observation port.
Further, the size C of the surface light source and the size B of the viewing port satisfy:
C/B≥f/(v-f)
wherein f is the focal length of the first lens, and v is the distance from the surface light source image to the first lens.
Further, the light emitting module includes: the surface light source, the second lens and the light splitting module;
the surface light source emits the incident detection light;
the light splitting module is used for transmitting/reflecting the incident detection light from the surface light source towards the observation port, and correspondingly reflecting/transmitting the emergent detection light reflected by the object to be detected and emitted through the observation port towards the light detection module;
the second lens is used for transmitting and condensing the incident detection light from the surface light source, the surface light source forms an image of the surface light source through the second lens and the light splitting module at the position of the observation port and above, and the image of the surface light source forms a light emitting surface of the incident detection light;
the light detection module and the observation port are arranged in a center alignment mode, or the light detection module is arranged in a center alignment mode relative to an image formed by the light splitting module and the observation port.
Further, the surface light source includes an LED surface light source, or the surface light source is formed of a point light source or laser-irradiated frosted glass, or the surface light source includes a light source having lambertian radiator properties.
Further, the reflectivity optical measurement device further comprises a control module, the light detection module comprises a light intensity detector, the light intensity detector detects a light intensity signal of the emergent detection light and transmits the light intensity signal to the control module, and the control module calculates the reflectivity of the object to be measured according to the intensity of the incident detection light and the intensity of the emergent detection light.
Further, the reaction chamber is an MOCVD reaction chamber.
Compared with the prior art that parallel collimated light beams (such as laser) are converged into incident light beams through complex optical light paths and then vertically projected onto an object to be measured from the center of an observation port and reflected on the surface of the object to be measured, the reflectivity optical measurement device provided by the invention has the advantages that the light emitting module with a certain light emitting surface is adopted to emit non-parallel light as incident detection light, so that no matter the optical measurement device is arranged between the optical measurement device and the observation port on a reaction chamber or the object to be measured is warped or inclined, the incident detection light emitted by the light emitting surface still enters the observation port and is reflected by the object to be measured and then is emitted through the observation port to be detected by the light detection module, the light path adjustment is simpler, the measurement device can not be limited by excessive installation positions, the purposes of simplifying the light paths and increasing the reliability are achieved, and the reflectivity optical measurement device is particularly suitable for measuring the object to be measured with large warping. Further, by matching the size of the light emitting surface of the light emitting module with the size of the observation port and designing the solid angle range in which the light emitting intensity is uniformly distributed and consistent, it is possible to further ensure that the measurement of the reflectance and the temperature measurement based thereon are effectively usable. In addition, the setting position of the light emitting module can meet various installation requirements, and can be adjusted according to the field requirements of field equipment, so that the application scene of the light emitting module is widened.
Drawings
FIGS. 1-3 are schematic diagrams illustrating a reflectivity optical measurement device according to a preferred embodiment of the present invention;
FIG. 4 is a schematic diagram of an optical path for laser imaging according to the prior art;
fig. 5 is a schematic view of an optical path of a planar light source imaging according to the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. Unless otherwise defined, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. As used herein, the word "comprising" and the like means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof without precluding other elements or items.
The optical reflectivity measuring device is arranged outside a reaction chamber, wherein the reaction chamber can be a reaction chamber of film forming equipment for a semiconductor high-temperature growth process, and the film forming equipment comprises a gas phase reaction device, and can be a metal organic chemical vapor deposition device (MOCVD), a hydride vapor phase epitaxy device (HVPE), a plasma enhanced chemical vapor deposition device, a physical vapor deposition device (PVD) and the like. And an observation port is arranged on the reaction chamber, and the reflectivity optical measurement device is used for carrying out on-line measurement on the reflectivity of an object to be measured placed in the reaction chamber through the observation port. The object to be measured may be, for example, a tray or a wafer on a tray, etc., which is in a rotated state during epitaxial growth.
The reflectivity optical measurement device comprises a light emitting module and a light detection module; the light emitting module is used for emitting incident detection light, the light emitting module comprises a light emitting surface for emitting the incident detection light, the incident detection light is non-parallel light and has a certain divergence angle, and at least part of the incident detection light is projected onto a surface to be detected of an object to be detected in the reaction chamber through an observation port on the reaction chamber and is reflected by the surface to be detected; the light detection module is used for receiving emergent detection light reflected by the detected surface and emitted through the observation port.
In some embodiments, the reflectance optical measurement device further comprises a control module. In some embodiments, the light detection module includes a light intensity detector, the light intensity detector detects a light intensity signal of the outgoing detection light and transmits the light intensity signal to the control module, and the control module calculates a reflectivity of the object to be detected according to the intensity of the incoming detection light and the intensity of the outgoing detection light, so that information of the emissivity can be obtained, and thus a temperature of the object to be detected is calculated according to a planck equation.
In some embodiments, the light emitting surface from which the incident probe light is emitted is disposed opposite to the observation port, and the light emitting surface is sized to meet certain requirements, so that within a given size range of the observation port, it is ensured that certain incident probe light can enter the observation port, and certain emergent probe light can exit from the observation port. Defining H as the distance from the light emitting surface emitting the incident detection light to the plane where the object to be detected is located, where H is the distance from the observation port to the plane where the object to be detected is located, and then the size a of the light emitting surface and the size B of the observation port satisfy: A/B is more than or equal to H/H. Preferably, H/h.ltoreq.A/B.ltoreq.2H/H. By matching the dimensions of the light emitting surface and the dimensions of the viewing port, a measurement of the reflectance can be ensured.
In some embodiments, if the object to be measured is warped, the incident probe light may enter the viewing port, and the emergent probe light may emerge from the viewing port, where the size of the viewing port should meet a certain requirement. And representing the warpage by using the inclination gamma of the object to be measured (namely the included angle of the tangent line where the measured point is positioned relative to the horizontal plane), wherein the half vertex angle alpha is more than or equal to 2 gamma. And obtaining the design size of the observation port in a certain warping range through the half-vertex angle alpha and the distance h between the observation port and the plane of the object to be measured. In the size range of the observation port, the reflectivity measurement in the condition that the gradient of the object to be measured is less than or equal to gamma can be satisfied.
In some embodiments, the intensity distribution of the incident probe light emitted at each of the light emitting surfaces from which the incident probe light is emitted is made uniform within a certain solid angle normal to the light emitting surfaces, preferably, the intensity non-uniformity (the ratio of the standard deviation of the intensity value to the average value of the intensity) is 2% or less, and the intensity distribution thereof within the solid angle is uniform throughout, thereby further ensuring that the obtained reflectance is usable effectively without affecting the stability of temperature measurement. On the other hand, the reflectance fluctuates depending on the intensity of the incident probe light, and the actual reflectance cannot be represented and cannot be used for calculating the temperature. Specifically, half of the angle at which the solid angle opens in any direction is defined as beta, and the beta is greater than or equal to a half apex angle alpha of a cone formed between the projection of the center of the observation port on the plane where the object to be measured is located and the observation port. Preferably, the β/α range is 1 to 2.
According to the reflectivity optical measurement device provided by the invention, the light emitting module with a certain light emitting surface emits non-parallel light as incident detection light, so that no matter whether the optical measurement device is offset from the observation port on the reaction chamber or the object to be measured is warped or inclined, although the light vertically incident on the object to be measured from the center of the observation port cannot be detected, the incident detection light emitted from other positions or other angles on the light emitting surface can still enter the observation port and be reflected by the object to be measured and then emitted out of the observation port to be detected by the light detection module, the light path adjustment is simpler, the measurement device can not be limited by excessive installation positions, the purposes of simplifying the light path and increasing the reliability are achieved, and the reflectivity optical measurement device is particularly suitable for measuring the object to be measured with large warping. The light emitting surface size and the light emitting intensity of the light emitting module are uniformly distributed and the consistent solid angle range is designed, so that the measurement of reflectivity and the temperature measurement based on the reflectivity can be further ensured to be effectively used.
The following describes the embodiments of the present invention in further detail with reference to the accompanying drawings.
Example 1
Referring to fig. 1, fig. 1 is a schematic structural diagram of an optical reflectivity measuring device according to a preferred embodiment of the invention. As shown in fig. 1, the optical measuring device for reflectivity of the present invention includes a light emitting module and a light detecting module 13 disposed above a viewing port 11. The light emitting module includes a surface light source 12.
Wherein the viewing port 11 is located above the object to be measured 10. The surface light source 12 constitutes a light emitting surface of the incident probe light for emitting the incident probe light, which is non-parallel light. At least part of the incident probe light emitted from the surface light source 12 is projected onto the surface to be measured of the lower object to be measured 10 after passing through the observation port 11. The light detection module 13 is configured to receive outgoing detection light reflected by the surface to be detected and emitted through the observation port 11.
Please refer to fig. 1. In some embodiments, the surface light source 12 may be provided with a planar (or approximately planar) light emitting surface. Also, the light emitting surface of the surface light source 12 may be disposed facing the viewing port 11 so that a parallel positional state is formed therebetween.
Meanwhile, the surface light source 12 may be provided with a receiving hole penetrating the surface of the surface light source 12. The light detection module 13 may be disposed above the receiving hole. Thus, the light detection module 13 can receive the outgoing detection light reflected on the surface to be detected and emitted through the observation port 11 through the receiving hole.
In some embodiments, the aperture of the receiving aperture is equal to or greater than the size of the detection face of the light detection module 13.
In the present embodiment, an integrated measuring system is used, and by forming a hole in the center of the surface light source 12 as a detection hole (receiving hole) of the light detection module 13, many optical elements are omitted, simplifying the light path.
In some embodiments, the light detection module 13 may be disposed directly in the receiving aperture. Further, the detection surface (lower surface) of the light detection module 13 may be flush with the light emitting surface (lower surface) of the surface light source 12.
Please refer to fig. 1. In some embodiments, the width a of the surface light source 12 in the horizontal direction and the width B of the viewing port 11 in the horizontal direction meet certain conditions, so that whether the mounting is offset or the epitaxial wafer is warped, incident detection light energy enters the viewing port 11 and is reflected by the object to be detected 10, and then exits through the viewing port 11 to be detected by the light detection module.
Specifically, please refer to fig. 1. In some embodiments, the receiving aperture, the light detecting module 13 and the viewing port 11 may be disposed in a centered manner, and preferably, the surface light source 12 is also disposed in a centered manner with the receiving aperture, the light detecting module 13 and the viewing port 11. The width a of the surface light source 12 in the horizontal direction may satisfy the following condition:
the first intersection point formed by the connection line between the center of the light detection module 13 (the receiving hole) and the center of the observation port 11 on the measured surface is a first endpoint o (i.e. the projection of the center of the observation port 11 on the plane of the object 10 to be measured), the two side edges of the observation port 11 are a second endpoint p and a third endpoint q, a straight line is formed between the first endpoint o and the second endpoint p and extends to the surface light source 12 to form a second intersection point s, meanwhile, a straight line is formed between the first endpoint o and the third endpoint q and extends to the surface light source 12 to form a third intersection point t, an isosceles triangle is formed between the endpoint o, the endpoint s and the endpoint t, a straight line is formed between the endpoint o and the endpoint s, an included angle formed between the straight line and the central connection line is the half vertex angle alpha of a cone formed between the projection of the center of the observation port 11 on the plane of the object 10 to be measured and the observation port 11, and H is the distance from the surface light source 12 to the plane of the object 10 to be measured, and H is the distance from the observation port 11 to the plane of the object 10 to be measured.
In this state, the width a of the surface light source 12 in the horizontal direction is equal to or greater than the distance M between the second intersection s and the third intersection t, and the distance m=2h×tgα. The width B of the viewing port 11 in the horizontal direction is the distance between the end point p and the end point q, and the width b=2h×tgα, that is, M/b=h/H. As the width A is larger than or equal to the distance M, the A/B is larger than or equal to H/H. In this way, by matching the size of the light emitting surface and the size of the observation port, measurement of reflectance can be ensured.
In some embodiments, the distance H from the surface light source 12 to the plane of the object to be measured 10 may be within 500 mm.
In some embodiments, the distance h from the viewing port 11 to the plane of the object under test 10 may be between 100mm and 200 mm.
In some embodiments, the ratio between the width a of the surface light source 12 in the horizontal direction and the distance M between the second intersection s and the third intersection t may be 1 to 2 times. Namely H/H is less than or equal to A/B is less than or equal to 2H/H.
In some embodiments, the intensity distribution of the incident probe light emitted at each location on the light emitting surface of the surface light source 12 is uniform and consistent within a certain solid angle normal to the light emitting surface to further ensure that the obtained reflectivity is usable effectively without affecting the stability of temperature measurement. In some embodiments, the surface light source 12 may include a light source having lambertian emitter properties such that the incident probe light emitted at each location on the light emitting surface has a uniform and consistent intensity distribution over a solid angle normal to the light emitting surface.
Specifically, please refer to fig. 1. In some embodiments, the surface light source 12, the receiving hole, the light detecting module 13 and the viewing port 11 are disposed in a center-aligned manner, and the surface light source 12 directly emits the detection light toward the viewing port 11 (i.e., there is no shielding between the surface light source 12 and the viewing port 11), and defines half of the angle at which the solid angle opens in any direction as β, which satisfies the following condition: beta is larger than or equal to the half vertex angle alpha.
In some embodiments, the ratio between β and half-apex angle α may range from 1 to 2.
The matching of the dimensions and the positional relationship between the surface light source 12 and the viewing port 11 ensures that the detection light emitted from the surface light source 12 (lambertian illuminant) can achieve the best incidence effect in all directions.
In some embodiments, the surface light source 12 may also include an LED surface light source 12.
In some embodiments, the surface light source 12 may also be formed of a point light source or laser irradiated frosted glass.
In embodiment 1, the surface light source 12 with a certain light emitting surface is adopted to emit non-parallel light as incident detection light, and the size of the light emitting surface of the detection light beam is larger than or equal to the size of the observation port 11 by matching the sizes of the surface light source 12 and the observation port 11. And designing a solid angle range in which the luminous intensity is uniformly distributed and consistent ensures that the obtained reflectivity is effectively usable in application to temperature measurement.
Example 2
Please refer to fig. 2. Embodiment 2 differs from embodiment 1 in that the light emitting module in this embodiment includes a surface light source 12 and a first condensing imaging module 14.
In some embodiments, the first light-condensing imaging module 14 is disposed between the surface light source 12 and the viewing port 11. The first light-condensing imaging module 14 is configured to transmit and condense the detection light from the surface light source 12, and form a first real image 15 of the surface light source 12 at a position between the first light-condensing imaging module 14 and the viewing port 11. In this embodiment, the first real image 15 of the surface light source 12 forms the light emitting surface of the incident probe light.
In some embodiments, the first light gathering imaging module 14 may include a first lens.
In some embodiments, the first lens is disposed in parallel between the surface light source 12 and the viewing port 11, and the centers of the first lens, the surface light source 12 and the viewing port 11 are aligned.
Similarly, the width a' of the first real image 15 of the surface light source 12 in the horizontal direction and the width B of the viewing port 11 in the horizontal direction meet certain conditions, so that whether the mounting is offset or the epitaxial wafer is warped, it is ensured that incident detection light energy enters the viewing port 11 and is reflected by the object 10 to be detected, and then exits through the viewing port 11 to be detected by the light detection module 13. Define H as the distance from the first real image 15 of the surface light source 12 to the plane of the object 10 to be measured, and H as the distance from the viewing port 11 to the plane of the object 10 to be measured. Then A'/B is greater than or equal to H/H. In this way, by matching the size of the first real image 15 and the size of the observation port 11, measurement of reflectance can be ensured. Preferably, H/h.ltoreq.A'/B.ltoreq.2H/H.
Please refer to fig. 2. In some embodiments, the following condition may be satisfied between the width C of the actual surface light source 12 in the horizontal direction and the width B of the viewing port 11 in the horizontal direction:
according to the lens imaging formula:
(1/u)+(1/v)＝1/f，
the method can be calculated as follows:
u/v＝f/(v-f)，
the size of the first real image 15 of the surface light source 12 is equal to or larger than the size of the viewing port 11, so that it can be obtained that the width C of the surface light source 12 in the horizontal direction satisfies:
C/B≥f/(v-f)；
where u is the object distance, i.e. the distance between the surface light source 12 and the first lens, v is the image distance, i.e. the distance between the first real image 15 of the surface light source 12 and the first lens, and f is the focal length of the first lens.
In some embodiments, the first lens transmits and condenses the detection light from the surface light source 12, so that the first real image 15 of the surface light source 12 formed under the first lens is located right at the position of the aperture of the viewing port 11. At this time, u+v=l, where L is the installation height of the surface light source 12 above the viewing port 11. However, in the case of example 1, the surface light source 12 cannot be directly mounted at a position just at the aperture of the viewing port 11.
The first real image 15 of the surface light source 12, which is formed below the first lens by transmitting and condensing the detection light from the surface light source 12 with the first lens, is actually a light emitting surface of the detection light source in the equivalent sense by replacing the surface light source 12 with the formed first real image 15 of the surface light source 12. So that the mounting height of the surface light source 12 can be adjusted by providing an appropriate first lens.
Similarly, the intensity distribution of the incident detection light emitted from each location on the first real image 15 of the surface light source 12 is uniform and consistent within a solid angle normal to the plane of the first real image 15; defining half of the angle of opening the solid angle in any direction as beta ', wherein beta ' is larger than or equal to the half vertex angle alpha ' of a cone formed between the projection of the center of the observation port 11 on the plane of the object to be measured and the observation port 11. Further, by disposing the first lens such that the first real image 15 of the surface light source 12 formed under the first lens is positioned at the aperture position of the viewing port 11, the plane on which the viewing port 11 is positioned is taken as a new light emitting surface formed by the first real image 15 of the surface light source 12, and such that the incident light rays starting from the new light emitting surface have a divergence angle larger than the above-mentioned included angle α. Therefore, not only can all light beams from the surface light source 12 be guided into the observation port 11, the utilization rate of the incident light rays is improved, but also the incident light rays still have a larger divergence angle can be effectively ensured, so that more emergent detection light which can vertically irradiate to the upper part of the observation port 11 can be obtained.
Embodiment 2 on the basis of embodiment 1, a first lens is added between the surface light source 12 and the observation port 11, and the first real image 15 of the surface light source 12 is formed to replace the surface light source 12 as the light emitting surface of the detection light source in the equivalent sense, so that the light emitting surface is closer to the measured surface, the use of the large-sized surface light source 12 is not required, the cost and the installation space can be saved, and the installation height of the surface light source 12 can be adjusted by selecting a proper first lens, so that the use scene of the reflectivity optical measurement device is further enlarged.
Example 3
Please refer to fig. 3. Embodiment 3 differs from embodiment 2 in that the light emitting module in this embodiment includes a surface light source 12, a second light converging imaging module 17, and a spectroscopic module 16. The light splitting module 16 may be disposed at an intersection of the incident probe light and the outgoing probe light. The second condensing imaging module 17 may be disposed between the surface light source 12 and the light splitting module 16. The surface light source 12 forms an image of the surface light source 12 at a position of the observation port 11 or above by the action of the second lens 17 and the spectroscopic module 16.
Specifically, the light splitting module 16 may be configured to transmit the incident detection light from the surface light source 12 toward the observation port 11 and the object to be measured 10 below the observation port, and reflect the outgoing detection light reflected by the object to be measured 10 through the observation port 11 toward the light detecting module 13 accordingly. The second condensing imaging module 17 may be configured to transmit and condense the incident probe light from the surface light source 12, and form a second real image 15' of the surface light source 12 at a position above the viewing port 11 after transmitting through the light splitting module 16. Alternatively, the light splitting module 16 may be configured to reflect the incident probe light from the surface light source 12 toward the observation port 11 and the object to be measured 10 below the observation port, and transmit the outgoing probe light reflected by the object to be measured 10 through the observation port 11 toward the light detecting module 13 accordingly. The second condensing imaging module 17 may be configured to transmit and condense incident probe light from the surface light source 12, and form a second real image 15' of the surface light source 12 at a position above the viewing port 11 after being reflected by the light splitting module 16. Preferably, the light detection module 13 and the viewing port 11 are arranged in a centered manner.
In the present embodiment, the second real image 15' of the surface light source 12 constitutes the light emitting surface of the incident detection light.
In some embodiments, the light detection module 13 may be disposed in the direction of either the transmitted or reflected light beam of the light splitting module 16. When the light detection module 13 is disposed in the direction of the transmitted light beam of the spectroscopic module 16, the light detection module 13 and the viewing port 11 are disposed in a center-aligned manner. When the light detection module 13 is disposed in the direction of the reflected light beam of the spectroscopic module 16, the light detection module 13 is disposed in a center-aligned manner with respect to between the imaging formed by the spectroscopic module 16 and the observation port 11.
In some embodiments, the second condensing imaging module 17 may include a second lens.
In some embodiments, the light splitting module 16 may include any one of a beam splitter and a half mirror.
Similarly, in this embodiment, the formed second real image 15 'of the surface light source 12 is actually used to replace the surface light source 12 as the light emitting surface of the detection light source in the equivalent sense, and the width a″ of the second real image 15' of the surface light source 12 in the horizontal direction and the width B of the observation port 11 in the horizontal direction meet certain conditions, so that whether the installation is offset or the epitaxial wafer is warped, it is ensured that the incident detection light energy enters the observation port 11 and is reflected by the object 10 to be detected, and then exits through the observation port 11 to be detected by the light detection module 13. Define H as the distance from the second real image 15' of the surface light source 12 to the plane of the object 10 to be measured, and H as the distance from the viewing port 11 to the plane of the object 10 to be measured. Then A "/B is made greater than or equal to H/H. In this way, by matching the size of the second real image 15' with the size of the observation port 11, measurement of reflectance can be ensured. Preferably, H/h.ltoreq.A "/B.ltoreq.2H/H.
Similarly, the intensity distribution of the incident probe light emitted from each location on the second real image 15 'of the surface light source 12 is uniform and consistent within a solid angle normal to the plane of the second real image 15'; and defining half of the opening angle of the solid angle in any direction as beta ', wherein beta' is more than or equal to the half vertex angle alpha of a cone formed between the projection of the center of the observation port 11 on the plane of the object to be detected and the observation port 11.
Embodiment 3 on the basis of embodiment 2, by adding a spectroscopic system (beam splitter), the installation position of the surface light source 12 can be made to satisfy various installation requirements (for example, the surface light source 12 can be installed at a side position (with respect to the orientation of the light detection module 13 installed above)).
The surface light source 12 and the light detection module 13 may also be located at a position other than one plane, so that the installation scene may be enlarged.
The working principle of the present invention will be described in detail with reference to the accompanying drawings.
Please refer to fig. 4. In the prior art, a laser is used as a detection light source. When an object to be measured such as a wafer is warped during the process growth, since the laser emits parallel light, no optical signal enters the detector even if the plane of the laser is infinite (i.e., the virtual image of the laser is formed to be infinite).
Please refer to fig. 5. In the present invention, lambertian emitters (e.g., LED surface light sources 12, etc., which emit light beams having uniform and consistent intensity distribution throughout a certain solid angle) are used as detection light sources. Since the light emitted from the surface light source 12 is non-parallel light having a certain divergence angle, even if the wafer is inclined, the detection light incident in the vertical direction is deflected by the angle of the reflected light due to the inclination of the wafer, and thus cannot be emitted from the viewing port 11 to be detected, but the detection light incident at other angles can still be emitted from the viewing port 11 to be detected by the detector.
In summary, the invention uses the light emitting module with a certain light emitting surface to emit non-parallel light as incident detection light, and matches the relation size between the light emitting surface of the detection light and the observation port 11, so that the incident detection light beam can completely cover the observation port 11, no matter the optical measuring device is arranged between the observation port on the reaction chamber and the optical measuring device, or the object to be measured is warped or inclined, the incident detection light emitted from the light emitting surface can still enter the observation port and be reflected by the object to be measured and then emitted out of the observation port to be detected by the light detecting module, therefore, the light path adjustment is simpler, and the detection light beam can not be excessively limited by the installation position, thereby achieving the purposes of simplifying the light path and increasing the reliability. And by designing a solid angle range in which the emission intensity of the probe light is uniformly distributed and uniform, it is possible to further ensure that the obtained reflectance can be effectively used. The invention can be suitable for measuring the reflectivity and the temperature of the epitaxial wafer, especially for the epitaxial wafer inclined due to warping, and at least part of the detection light in the detection light beam can still be effectively received by the light detection module 13 through the emergent light of the observation port 11. The device of the invention can realize high integration, can meet various detection condition requirements by using the surface light source 12 with smaller size, and can enable the setting position of the surface light source 12 to meet various installation requirements, thereby widening the application scene of the invention.
While embodiments of the present invention have been described in detail hereinabove, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. It is to be understood that such modifications and variations are within the scope and spirit of the present invention as set forth in the following claims. Moreover, the invention described herein is capable of other embodiments and of being practiced or of being carried out in various ways.
Claims (12)
1. An optical reflectance measurement device, characterized in that it is disposed outside a reaction chamber, comprising: a light emitting module and a light detecting module;
the light emitting module is used for emitting incident detection light, the light emitting module comprises a light emitting surface for emitting the incident detection light, the incident detection light is non-parallel light, and at least part of the incident detection light is projected onto a tested surface of an object to be tested in the reaction chamber through an observation port on the reaction chamber and is reflected by the tested surface;
the light detection module is used for receiving emergent detection light reflected by the detected surface and emitted through the observation port.
2. The reflectance optical measurement apparatus according to claim 1, wherein the intensity of the incident probe light emitted at each place on the light-emitting face within a solid angle normal to the light-emitting face is uniformly distributed and the intensity distribution within the solid angle is uniform for each place; and defining half of the opening angle of the solid angle in any direction as beta, wherein beta is larger than or equal to the half vertex angle alpha of a cone formed between the projection of the center of the observation port on the plane of the object to be detected and the observation port.
3. The reflectance optical measurement device according to claim 2, wherein between the size a of the light emitting face and the size B of the viewing port:
A/B≥H/h
and H is the distance from the light emitting surface to the plane of the object to be detected, and H is the distance from the observation port to the plane of the object to be detected.
4. A reflectivity optical measurement mechanism as set forth in claim 3 wherein the dimensions a of said light emitting surface and the dimensions B of said viewing port satisfy: H/H is less than or equal to A/B is less than or equal to 2H/H.
5. The optical reflectance measuring apparatus according to claim 1, wherein the light emitting module includes a surface light source constituting a light emitting surface of the incident probe light, the surface light source is disposed facing the observation port, a receiving hole penetrating a surface is provided on the surface light source, the light detecting module receives the outgoing probe light reflected by the measured surface and emitted through the observation port through the receiving hole, wherein the receiving hole, the light detecting module, and the observation port are disposed in a center-aligned manner.
6. The reflectance optical measurement device according to claim 1, wherein the light emitting module comprises: a surface light source and a first lens,
the surface light source emits the incident probe light,
the first lens is positioned between the surface light source and the observation port, is used for transmitting and condensing the incident detection light from the surface light source, forms an image of the surface light source at the position between the first lens and the observation port, forms a light emitting surface of the incident detection light,
the surface light source is provided with a receiving hole penetrating through the surface, the light detection module receives the emergent detection light reflected by the detected surface and emitted by the observation port through the receiving hole, and the receiving hole, the light detection module and the observation port are arranged in a center alignment mode.
7. The optical reflectance measurement device according to claim 6, wherein the image of the surface light source is located at the position of the viewing port.
8. The optical reflectance measuring device according to claim 6, wherein a dimension C of the surface light source and a dimension B of the viewing port satisfy:
C/B≥f/(v-f)
wherein f is the focal length of the first lens, and v is the distance from the surface light source image to the first lens.
9. The reflectance optical measurement device according to claim 1, wherein the light emitting module comprises: a surface light source, a second lens and a light splitting module,
the surface light source emits the incident probe light,
the light splitting module is used for transmitting/reflecting the incident detection light from the surface light source towards the observation port, correspondingly reflecting/transmitting the emergent detection light reflected by the object to be detected and emitted through the observation port towards the light detection module,
the second lens is used for transmitting and condensing the incident detection light from the surface light source, the surface light source forms an image of the surface light source through the second lens and the light splitting module at the position of the observation port and above, the image of the surface light source forms the light emitting surface of the incident detection light,
the light detection module and the observation port are arranged in a center alignment mode, or the light detection module is arranged in a center alignment mode relative to an image formed by the light splitting module and the observation port.
10. The optical reflectance measuring device according to any one of claims 5, 6 or 9, wherein the surface light source comprises an LED surface light source, or the surface light source is formed of a point light source or laser-irradiated frosted glass, or the surface light source comprises a light source having lambertian radiator properties.
11. The reflectance optical measurement device according to claim 1, further comprising a control module, wherein the light detection module includes a light intensity detector that detects a light intensity signal of the outgoing detection light and transmits the light intensity signal to the control module, and wherein the control module calculates the reflectance of the object to be measured based on the intensity of the incoming detection light and the intensity of the outgoing detection light.
12. The reflectance optical measurement device according to claim 1, wherein the reaction chamber is a MOCVD reaction chamber.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211625238.4A CN116008234A (en) | 2022-12-16 | 2022-12-16 | Reflectivity optical measurement device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211625238.4A CN116008234A (en) | 2022-12-16 | 2022-12-16 | Reflectivity optical measurement device |
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| CN116008234A true CN116008234A (en) | 2023-04-25 |
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| CN202211625238.4A Pending CN116008234A (en) | 2022-12-16 | 2022-12-16 | Reflectivity optical measurement device |
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