TWI704329B - Online monitoring system and semiconductor processing equipment - Google Patents

Abstract

The online monitoring system and semiconductor processing device provided by the present invention include a light source, a first light path, a second light path, a sampling frequency control unit, a photoelectric conversion unit, and a calculation unit. The light source is used to provide incident light; and the first light path is used to transmit incident light. The second optical path includes a first branch and a second branch, which collect interference light and plasma reflected light respectively; the sampling frequency control unit is used to control the first optical path and the first The on and off of the branch and the second branch to realize the switching between the first optical path and the first branch and the second branch; the sampling frequency control unit is also used to adjust the switching frequency; photoelectric conversion The unit is used to convert interference light and plasma reflected light into electrical signals; the calculation unit is used to obtain the surface thickness of the wafer. The online monitoring system provided by the present invention can not only ensure the precise control of the thickness of the wafer surface, but also meet the needs of different processes.

Description

Online monitoring system and semiconductor processing equipment

The invention relates to the technical field of semiconductor manufacturing, in particular to an online monitoring system and a semiconductor processing device.

With the development of semiconductor process technology, a variety of semiconductor devices are widely used in the semiconductor process. Plasma etching or deposition is a key step in the semiconductor process. Plasma devices have been spread across major semiconductor process production lines. Among them, high-speed etching, as a process in the semiconductor process, is widely used in the packaging process, as well as electronic components and other fields. Due to the high etching rate and fast etching depth, instant monitoring of the etching profile and instant high-precision control of the etching depth become necessary. In traditional high-speed etching, process engineers often control the process time based on experience to control the etching depth, but the accuracy is not high, and real-time precise control cannot be achieved.

For this reason, currently an IEP (Interferometric Endpoint System) online monitoring system is used to monitor the process thickness of the wafer surface. The process thickness of the wafer surface may be the etching depth or the film deposition thickness. Figure 1 is a structural diagram of an existing online monitoring system. Please refer to Figure 1. The online monitoring system includes light source 5, spectroscopy software 6, spectrometer 4 and optical fiber assembly 2. In practical applications, the incident light of the corresponding narrow wavelength emitted by the light source 5 enters the chamber 3 through the optical fiber assembly 2, and radiates to the surface of the wafer 7 through the plasma 1 and is reflected on the surface; then, it is reflected by the wafer 7 The light is transmitted to the spectrometer 4 through the optical fiber assembly 2; the spectrometer 4 resolves the intensity of the reflected light. When the process thickness of the wafer 7 surface changes, the light intensity detected in the spectrometer 4 changes accordingly to obtain the change The intensity of the spectrum; the intensity of the spectrum is analyzed and calculated by the spectrum software 6 to obtain the corresponding relationship between the change in light intensity and the thickness of the wafer surface.

The above-mentioned online monitoring system inevitably has the following problems in practical applications: In the monitoring process, it is usually necessary to select a certain time interval to subtract the background light (plasma reflected light) of the plasma spectrum. Therefore, the above-mentioned light source 5 selects the pulse working mode shown in Figure 2, and the light source 5 emits during the on phase Laser, in the off phase, the light source 5 is turned off, and the background light of the plasma is collected at the same time. However, this causes the sampling frequency of the process thickness of the wafer surface to be limited by the pulse frequency of the light source 5. That is, the sampling frequency is the frequency at which the light source 5 is turned on, and the pulse frequency of the light source 5 is usually relatively fixed, resulting in comparison of the sampling frequency Single, unable to meet different process requirements, and thus unable to accurately control the process thickness of the wafer surface.

The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes an online monitoring system and a semiconductor processing device, which can realize the adjustment of the sampling frequency, so as not only to ensure accurate control of the thickness of the wafer surface, but also to meet Different manufacturing process needs.

In order to achieve the purpose of the present invention, an online monitoring system is provided for detecting the process thickness of the wafer surface, including a light source, a first light path, a second light path, a sampling frequency control unit, a photoelectric conversion unit, and a calculation unit, wherein the light source is used To provide incident light; the first optical path is used to transmit the incident light and radiate the incident light to the surface of the wafer; The second optical path includes a first branch and a second branch, which are respectively used to collect interference light and plasma reflected light, and transmit them to the photoelectric conversion unit. The interference light is reflected by the surface of the wafer. The interference light formed by the light and the incident light; the sampling frequency control unit is used to control the on-off of the first optical path, the first branch, and the second branch, so as to realize the connection between the first optical path and the first branch And switch on the second branch; the sampling frequency control unit is also used to adjust the switching frequency; the photoelectric conversion unit is used to convert the interference light and the plasma reflected light into electrical signals, and send To the calculation unit; the calculation unit is used to obtain light intensity data according to the electrical signal, and calculate the surface thickness of the chip according to the light intensity data.

Optionally, the sampling frequency control unit includes a diaphragm and a driving mechanism, wherein the sampling frequency control unit includes a diaphragm and a driving mechanism for driving the diaphragm to rotate, wherein the diaphragm includes a barrier portion and an opening portion, And under the drive of the driving mechanism, the opening can be rotated around the center of the barrier to a position corresponding to the first optical path and the first branch to connect the first optical path and the first branch, and at the same time The barrier portion rotates around the center of the barrier portion to a position corresponding to the second branch to break the second branch; or, the opening portion rotates around the center of the barrier to a position corresponding to the second branch. Corresponding position to connect the second branch, while the barrier part rotates around the center of the barrier part to the position corresponding to the first optical path and the first branch, to disconnect the first optical path and the second branch One way.

Optionally, the online monitoring system further includes a light-shielding tube, the first light path, the first branch and the second branch are all arranged in the light-shielding tube, and the light transmission direction of the three is parallel to the light-shielding tube Axis; and, the first optical path and the first branch are located on the same side of the axis of the light-shielding tube with respect to the axis of the light-shielding tube, and the second branch is located on the opposite side of the first light path and the first branch The diaphragm is arranged in the light shielding barrel, and the rotation axis of the diaphragm coincides with the axis of the light shielding barrel.

Optionally, each of the first light path, the first branch and the second branch includes a first part and a second part spaced apart along the respective light transmission direction, wherein the first part is used to face the The two parts emit light; the second part is used to receive the light; the diaphragm is arranged between the first part and the second part.

Optionally, the sampling frequency control unit includes a power supply for supplying power to the light source at a preset frequency, and the preset frequency of the power supply is adjustable; the photoelectric conversion unit includes a first subunit and a second subunit , The two are respectively used to convert the interference light and the plasma reflected light into electrical signals; wherein, the power source is triggered synchronously with the first subunit; the power source is triggered asynchronously with the second subunit.

Optionally, the photoelectric conversion unit includes a photomultiplier tube; the intensity of the interference light and the reflected light of the plasma can be adjusted by adjusting the voltage applied to the photomultiplier tube.

Optionally, the online monitoring system further includes a filter element used to filter the incident light in the first optical path, the interference light in the first branch, and the second branch. The plasma reflects light to pass light of a specified wavelength.

Optionally, the filter element includes a rotation axis and a plurality of filters with different wavelength bands arranged around the rotation axis, and the rotation axis is used to drive the plurality of filters to rotate around the rotation axis, so that three of them The filters of the designated wavelength are respectively rotated to positions corresponding to the first optical path, the first branch and the second branch.

Optionally, the number of the optical filters is 8, and the central angle between two adjacent optical filters is 45°.

Optionally, the online monitoring system further includes a lens arranged between the emitting end of the first optical path and the surface of the wafer, and between the receiving end of the second optical path and the surface of the wafer, and used to transmit data from the second optical path. The incident light at the emitting end of an optical path diverges and radiates to the surface of the chip, while the reflected light is converged and radiated to the receiving end of the second optical path.

As another technical solution, the present invention also provides a semiconductor processing device, including a reaction chamber, a susceptor for carrying a wafer is arranged in the reaction chamber, and an upper electrode mechanism is arranged on the top of the reaction chamber, and The above-mentioned online monitoring system provided by the present invention is used to detect the process thickness of the wafer surface.

Optionally, the online monitoring system further includes a lens, which is arranged between the emitting end of the first optical path and the surface of the wafer, and between the receiving end of the second optical path and the surface of the wafer, for the incident light Diverging radiation to the surface of the chip, while converging and radiating the reflected light to the receiving end of the second optical path; The output end of the first optical path and the input end of the second optical path are located above the lens; the photoelectric conversion unit and the calculation unit are both located outside the reaction chamber.

Optionally, the upper electrode mechanism includes a dielectric window disposed above the base; the lens is disposed in the dielectric window and located at the center of the dielectric window, And the lens is exposed from the side of the dielectric window away from the base; Alternatively, the lens is arranged at the center of the dielectric window and is located on the side away from the base.

The present invention has the following beneficial effects: The online monitoring system provided by the present invention controls the on and off of the first optical path, the first branch and the second branch by means of the sampling frequency control unit, which can realize the connection between the first optical path and the first branch and the second branch. The switching between the two branches can realize the switching between collecting the interference light and collecting the background light of the plasma. At the same time, the sampling frequency control unit is also used to adjust the switching frequency, that is, to adjust the sampling frequency of the process thickness of the wafer surface. The sampling frequency control unit can determine the size of the sampling frequency without being limited by the frequency of the light source, thus not only can guarantee Accurately control the thickness of the wafer surface, and can meet the needs of different manufacturing processes.

The semiconductor processing device provided by the present invention can not only ensure the precise control of the thickness of the wafer surface, but also meet the needs of different processes by using the online monitoring system provided by the present invention.

In order to enable those skilled in the art to better understand the technical solution of the present invention, the online monitoring system and semiconductor processing device provided by the present invention will be described in detail below in conjunction with the accompanying drawings.

Please refer to Fig. 3, the online monitoring system provided by the first embodiment of the present invention is used to detect the surface thickness of the wafer in real time during the manufacturing process to accurately control it. The wafer surface thickness refers to the process thickness of the wafer surface, which may be the etching depth of the etching process or the film deposition thickness of the deposition process. The online monitoring system includes a light source 43, a first light path 39, a second light path, a sampling frequency control unit, a photoelectric conversion unit, and a calculation unit. The light source 43 is used to provide incident light. Optionally, the light source 43 is a multi-spectral laser. Sources, such as mercury lamps, to be able to accommodate different etching materials. The first optical path 39 is used to transmit the incident light from the light source 43 and radiate the incident light to the surface of the wafer 22. The optical fiber head 37 of the first optical path 39 is located above the wafer 22. The optical fiber head 37 is a connector device with a lens for fixing optical fibers. The lens can only transmit light without changing the direction of light.

The second optical path includes a first branch 40 and a second branch 41, which are respectively used to collect interference light and plasma reflected light, and transmit them to the photoelectric conversion unit. The interference light is reflected light reflected by the surface of the wafer Interfering light with incident light. The plasma reflected light is the light reflected by the plasma 21 after absorbing the incident light. In practical applications, the plasma reflected light as background light needs to be removed after the light source 43 is turned on for a period of time, and when removing the background light, the first light path 39 and the first branch 40 must be closed. In addition, the optical fiber head 38 of the second optical path is located above the wafer 22 and is arranged side by side with the optical fiber head 37 of the above-mentioned first optical path 39. The optical fiber head 38 is also a lensed joint device for fixing optical fibers.

The sampling frequency control unit is used to control the on and off of the first optical path 39, the first branch 40 and the second branch 41, so as to realize the connection between the first optical path 39 and the first branch 40 and the second branch 41. Switching between the collection of interference light and the background light of the plasma can be realized. At the same time, the sampling frequency control unit is also used to adjust the switching frequency, which is the sampling frequency for detecting the process thickness of the wafer surface.

The online monitoring system provided by the present invention adjusts the sampling frequency with the aid of the above-mentioned sampling frequency control unit. The sampling frequency control unit can determine the size of the sampling frequency without being limited by the frequency of the light source, thereby not only ensuring precise control of the wafer surface process Thickness, and can meet the needs of different manufacturing processes.

In this embodiment, the aforementioned sampling frequency control unit includes a diaphragm 49 and a driving mechanism (not shown in the figure) for driving the diaphragm 49 to rotate, wherein the diaphragm 49 includes a barrier portion 491 and an opening portion 492, such as As shown in FIG. 4, the diaphragm 49 has a disk shape, and the area on the diaphragm 49 except the opening 492 constitutes a barrier portion 491. Driven by the driving mechanism, both the barrier portion 491 and the opening portion 492 can rotate around the center of the barrier portion 491. Specifically, under the driving of the driving mechanism, the opening 492 can wrap around the screen The center of the barrier portion 491 is rotated to a position corresponding to the first optical path 39 and the first branch 40 to connect the first optical path 39 and the first branch 40, while the barrier portion 491 rotates around the center of the barrier portion 491 to At a position corresponding to the second branch 41 to disconnect the second branch 41; or, the opening 492 rotates around the center of the barrier portion 491 to a position corresponding to the second branch 41 to connect the second branch 41. At the same time, the barrier portion 491 rotates around the center of the barrier portion 491 to the position corresponding to the first optical path 39 and the first branch 40 to disconnect the first optical path 39 and the first branch 40, thereby realizing the Switching between the first light path 39 and the first branch 40 and the second branch 41 is connected.

The opening 492 is rotated to a position corresponding to the first optical path 39 and the first branch 40 or rotated to a position corresponding to the second branch 41, which means that the opening 492 is located in the first optical path 39 and the first branch. 40 or on the light transmission path of the second branch 41, so that the light transmitted by the first light path 39 and the first branch 40 or the light transmitted by the second branch 41 will not be blocked. The above-mentioned barrier portion 491 rotates to a position corresponding to the first light path 39 and the first branch 40 or to a position corresponding to the second branch 41, which means that the barrier portion 491 is located at the first light path 39 and the first branch On the light transmission path of 40 or on the light transmission path of the second branch 41, the light transmitted by the first light path 39 and the first branch 40 or the light transmitted by the second branch 41 is blocked.

In addition, the above-mentioned sampling frequency control unit can adjust the frequency of switching between connecting the first optical path 39 and the first branch 40 and the second branch 41 by adjusting the rotation speed of the diaphragm 49, that is, the inspection wafer The sampling frequency of the process thickness of the surface. The higher the speed, the greater the sampling frequency; anyway, the smaller the sampling frequency. For example, if the rotation speed is 6000 rpm, the sampling frequency is 6000 Hz.

The sampling frequency depends only on the rotation speed of the diaphragm 49 described above. In practical applications, the desired rotation speed of the diaphragm 49 can be determined according to the process requirements, and a driving mechanism such as a motor that meets the corresponding rotation speed can be selected. Since a driving mechanism such as a motor can provide a wide range of rotation speed, the size of the sampling frequency determined by the rotation speed of the diaphragm 49 is not limited. Moreover, because the desired rotation speed of the diaphragm 49 can be determined according to different process requirements, the sampling frequency of the online monitoring system provided by the present invention can actually meet different process requirements.

By adjusting the sampling frequency with the aid of the above-mentioned sampling frequency control unit, different sampling results can be obtained. In practical applications, the sampling frequency can be selected according to different etching rates. Specifically, for a process with a relatively low etching rate, such as a process with an etching rate of 500 nm/min, if the process requires a monitoring depth difference of less than 10 nm per second, the sampling frequency can be selected in the range of >50 samples/min. For a process with an etching rate of 2um/min, and the process requires a monitoring depth difference of less than 10nm per second, the sampling frequency can be selected in the range of >200samples/min.

In this embodiment, the online monitoring system further includes a light shielding tube 47. The first light path 39, the first branch 40 and the second branch 41 are all arranged in the light shielding tube 47, and the light transmission direction of the three is parallel to The axis of the light shielding cylinder 47 (the axis of the light shielding cylinder 47 in the horizontal direction in FIG. 3). Preferably, the first light path 39 and the first branch 40 are located on the same side (upper side) of the axis of the light shielding cylinder 47, and the second branch 41 is located between the first light path 39 and the first branch relative to the axis of the light shielding cylinder 47. Opposite side of road 40 (lower side).

The diaphragm 49 is provided in the light-shielding barrel 47, and the rotation axis of the diaphragm 49 coincides with the axis of the light-shielding barrel 47, so that, driven by the driving mechanism, the barrier portion 491 and the opening portion 492 both surround the light-shielding barrel 47. Since the first optical path 39 and the first branch 40 are located on the same side of the axis of the light-shielding barrel 47, the second branch 41 is located on the first light path 39 and the first branch relative to the axis of the light-shielding barrel 47 On the opposite side of 40, when the opening 492 rotates to the side where the first light path 39 and the first branch 40 are located, it can correspond to the first light path 39 and the first branch 40 at the same time, and the barrier 491 and the second branch 40 When the opening 492 rotates to the side where the second branch 41 is located, it can correspond to the second branch 41, and the barrier 491 corresponds to the first light path 39 and the first branch 40 at the same time.

In this embodiment, each of the first light path 39, the first branch 40, and the second branch 41 includes a first part and a first part arranged at intervals along the respective light transmission direction (in this embodiment, the axial direction of the light shielding tube 47). The second part (for example, the first light path 39 shown in Figure 3, includes a first part 391 and a second part 392, which are located inside the light shielding cylinder 47 and are respectively close to the left and right ends of the light shielding cylinder 47 ), where the first part is used to emit light (incident light) toward the second part; the second part is used to receive the light. The diaphragm 49 is arranged between the first part and the second part to block or connect the light propagation between the first part and the second part by rotation.

The online monitoring system also includes a lens 36 which is arranged between the transmitting end (optical head 37) of the first optical path 39 and the surface of the wafer 22 and the receiving end of the second optical path (optical fiber head 38) and the surface of the wafer 22 In between, it is used to diverge and radiate the incident light from the transmitting end (fiber head 37) of the first optical path 39 to the surface of the wafer 22, while converging and radiating the reflected light to the receiving end of the second optical path to further increase the light intensity .

The photoelectric conversion unit is used to convert interference light and plasma reflected light into electrical signals and send them to the calculation unit 46. In this embodiment, the photoelectric conversion unit includes a first subunit 45 and a second subunit 44, which are respectively used to convert interference light and plasma reflected light into electrical signals. The calculation unit 46 is used for obtaining light intensity data according to the electrical signal, and calculating the process thickness of the wafer surface according to the light intensity data. When the computing unit 46 receives the electrical signal, it processes the electrical signal. The processing process mainly includes difference calculation, signal conversion and sampling, etc., to obtain light intensity data.

In the prior art, please refer to Fig. 6, where a dotted line with arrows represents reflected light, and a solid line with arrows represents incident light. When the etching depth increases, because the etching bottom is not smooth, the reflection of the incident light on the etching bottom is non-specular reflection, so part of the reflected light from the etching bottom will not directly point to the lens 36, but will point to other parts of the etching bottom And it is blocked by the etched bottom of this part, which causes the overall signal of the reflected light to weaken, and finally causes the intensity of the interference light to weaken. However, the photoelectric converter (such as CCD element) used in the prior art can only enter normal operation when the light is stronger than a certain value. Status (that is, capable of signal collection, and the photoelectric conversion capability meets the working requirements, and the signal-to-noise ratio also meets the working requirements), that is, the current of the photoelectric conversion device has a certain critical value relationship with the light intensity, that is, the light intensity must Only when this critical value is reached can the photoelectric conversion device enter a normal working state.

Although the existing photoelectric converter has a certain light intensity signal enhancement function, it needs a certain photoelectric conversion time to enhance the light intensity signal, and for the case where the etching depth is deep, the reflected light is blocked by the etched deep groove. The intensity of the reflected light reflected to the lens 36 is relatively weak, and the photoelectric conversion capability of the existing photoelectric converter is limited, and the weak light intensity signal cannot reach the critical value, thereby affecting the detection accuracy.

In order to solve the above problem, in this embodiment, the first subunit 45 and the second subunit 44 both use photomultiplier tubes. By adjusting the voltage applied to the photomultiplier tube, the interference light and plasma reflection can be adjusted. The intensity of light, because the photomultiplier tube has a strong photoelectric conversion ability, so even when the intensity of the reflected light is weak, it can make the size of the light intensity signal and the signal-to-noise ratio meet the working requirements through photoelectric conversion, so as to ensure The accuracy of detection.

The photomultiplier tube is an electronic vacuum device based on the external photoelectric effect and the secondary electron emission effect. It uses secondary electron emission to multiply the escaping photoelectrons, so it can measure weak light signals, so its measurement sensitivity is much higher than that of photoelectric tubes. FIG. 5 is a structural diagram of the photomultiplier tube used in the first embodiment of the present invention. Please refer to FIG. 5. The photomultiplier tube includes a plurality of electrodes 452 and a power supply 451 for applying voltage to each electrode 452. When the photomultiplier tube is in operation, electrons will be emitted to the electrode at a high speed under the action of the electric field, and more secondary emission electrons will be generated. If this continues, the secondary emission electrons excited by each photoelectron increase exponentially, and finally The anode is collected to obtain a stronger light signal. Due to the fast response time of the photomultiplier tube, even when the intensity of the reflected light is weak, it does not take much photoelectric conversion time. When the etching depth increases, the voltage can be gradually changed during the manufacturing process based on the initially set voltage according to the etching requirements. It can be seen that the photomultiplier tube adjusts the signal intensity by adjusting the voltage. Compared with the non-time integration method adopted in the prior art, the embodiment of the present invention can effectively shorten the sampling time and increase the sampling frequency.

In this embodiment, the online monitoring system further includes a filter element 48, which is used to filter the incident light in the first optical path 39, the interference light in the first branch 40, and the second branch 41. The plasma in the reflector reflects light to pass light of a specified wavelength. For different etching materials, the appropriate spectral line can be selected according to the reflectivity of the spectral line corresponding to the etching material (generally the spectral line with high emissivity is selected), with the help of the filter element 48, the spectral line selection can be performed by selecting the filter .

Preferably, as shown in Fig. 7, the filter element 48 includes a rotation axis 42 and a plurality of filters 481 of different wavelength bands arranged around the rotation axis 42. The rotation axis 42 is used to drive the plurality of filters 481 around The rotating shaft 42 rotates so that the three filters 481 of designated wavelengths rotate to positions corresponding to the first optical path 39, the first branch 40, and the second branch 41, respectively. In this way, the three filters 481 of specified wavelengths can filter the light transmitted by the three first optical paths 39, the first branch 40 and the second branch 41 respectively. For example, the number of filters 481 may be 8, and the central angle between two adjacent filters 481 is 45°. This central angle facilitates the alignment of the optical path and the filter.

Compared with the above-mentioned first embodiment, the online monitoring system provided by the second embodiment of the present invention differs only in the structure of the sampling frequency control unit.

Specifically, as shown in Figure 8, in this embodiment, the sampling frequency control unit includes a power supply 51 for supplying power to the light source 43 at a preset frequency, and the preset frequency of the power supply 51 is adjustable, so that Realize the adjustment of sampling frequency. In addition, the power supply 51 is triggered synchronously with the first subunit 45 of the photoelectric conversion unit; the power supply 51 and the second subunit 44 are triggered asynchronously, that is, when the first light path 39 and the first branch 40 are connected, and the second branch is connected The switching between the paths 41 can thereby realize the switching between collecting the interference light and collecting the background light of the plasma.

In this embodiment, the sampling frequency depends on the preset frequency of the power supply 51. In practical applications, the preset frequency of the power supply 51 can be determined according to the process requirements. Since the preset frequency has a wide selection range, the size of the sampling frequency determined by the preset frequency is not limited. Moreover, because the preset frequency of the power supply 51 can be determined according to different process requirements, the sampling frequency of the online monitoring system provided by the present invention can actually meet different process requirements.

As another technical solution, please refer to FIG. 9. An embodiment of the present invention also provides a semiconductor processing apparatus, including a reaction chamber, in which a susceptor 23 for carrying the wafer 22 is provided, and is located in the reaction chamber An upper electrode mechanism is provided on the top. In addition, it also includes the online monitoring system provided by the above embodiments of the present invention, which is used to detect the thickness of the wafer surface.

The semiconductor processing apparatus provided by the embodiments of the present invention can not only ensure accurate control of the wafer surface thickness, but also meet the needs of different manufacturing processes by adopting the online monitoring system provided by the foregoing embodiments of the present invention.

In this embodiment, the above-mentioned upper electrode mechanism includes a dielectric window 20 disposed above the base 23. The lens 36 is disposed in the dielectric window 20 and located at the center of the dielectric window 20, and the lens 36 is exposed from the side of the dielectric window 20 away from the base 23, and the lens 36 is in the dielectric window 20. The side of the window 20 close to the base 23 is not exposed, so as to prevent the lens 36 from directly contacting the plasma, and to prevent the lens 36 from being etched and affecting the manufacturing process. In addition, the output end (fiber head 37) of the first optical path 39 and the input end (fiber head 38) of the second optical path are located above the lens 36; the photoelectric conversion unit and the calculation unit 46 are both located outside the reaction chamber.

The above-mentioned lens 36 is arranged in the dielectric window 20 in an embedded manner, which can reduce the interference of the dielectric window 20 on the light source such as attenuation. At the same time, by placing the lens 36 at the center of the dielectric window 20, the influence of factors such as process unevenness on the spectrum can be avoided, thereby improving the etching uniformity or deposition uniformity of the wafer.

It should be noted that, in this embodiment, the lens 36 is embedded in the dielectric window 20. However, the present invention is not limited to this. In practical applications, the lens 36 can also be arranged at the center of the dielectric window 20 and on the side away from the base 23, that is, the lens 36 is located on the dielectric window. The upper surface of 20.

In addition, the upper electrode mechanism also includes a coil 19 arranged above the dielectric window 20, which is electrically connected to the upper matching device 17 and the upper radio frequency power supply 16 in turn. The RF power provided by the upper RF power supply 16 is applied to the coil 19 and coupled to the reaction chamber through the dielectric window 20 to excite the process gas entering the reaction chamber through the gas inlet pipe 18 to generate plasma 21. In addition, the susceptor 23 is electrically connected to the lower RF power supply 25 through the lower matcher 24 so as to generate a bias voltage on the surface of the wafer 22 to attract plasma to etch the wafer surface.

It can be understood that the above implementations are merely exemplary implementations used to illustrate the principle of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

1, 21‧‧‧Plasma 2‧‧‧Fiber optic components 3‧‧‧ Chamber 4‧‧‧Spectrometer 5. 43‧‧‧Light source 6‧‧‧Spectroscopy software 7, 22‧‧‧chip 16‧‧‧on RF power supply 17‧‧‧Upper matcher 18‧‧‧Air intake pipe 19‧‧‧Coil 20‧‧‧Dielectric Window 22‧‧‧Chip 23‧‧‧Base 24‧‧‧Down matcher 25‧‧‧Under RF power 36‧‧‧Lens 37、38‧‧‧Optical fiber head 39‧‧‧First Light Path 40‧‧‧First Branch 41‧‧‧Second Branch Road 42‧‧‧Rotation axis 44‧‧‧Second subunit 45‧‧‧First subunit 46‧‧‧Computer unit 47‧‧‧Shading tube 48‧‧‧Filter assembly 49‧‧‧Aperture 51, 451‧‧‧Power 391‧‧‧Part One 392‧‧‧Part Two 452‧‧‧electrode 481‧‧‧Filter 491‧‧‧Barrier Department 492‧‧‧ Opening

Figure 1 is a structural diagram of an existing online monitoring system; Figure 2 is a schematic diagram of the pulse working mode of the existing light source; Figure 3 is a structural diagram of the online monitoring system provided by the first embodiment of the present invention; Figure 4 is a structural diagram of an aperture used in the first embodiment of the present invention; Figure 5 is a structural diagram of a photomultiplier tube used in the first embodiment of the present invention; Figure 6 is a schematic diagram of incident light radiating onto the surface of the wafer; Figure 7 is a structural diagram of a filter assembly used in the first embodiment of the present invention; Figure 8 is a structural diagram of the online monitoring system provided by the second embodiment of the present invention; FIG. 9 is a cross-sectional view of a semiconductor processing apparatus according to an embodiment of the invention.

21‧‧‧Plasma

22‧‧‧Chip

36‧‧‧Lens

37、38‧‧‧Optical fiber head

39‧‧‧First Light Path

40‧‧‧First Branch

41‧‧‧Second Branch Road

42‧‧‧Rotation axis

43‧‧‧Light source

44‧‧‧Second subunit

45‧‧‧First subunit

46‧‧‧Computer unit

47‧‧‧Shading tube

48‧‧‧Filter assembly

49‧‧‧Aperture

391‧‧‧Part One

392‧‧‧Part Two

Claims (12)

An online monitoring system for detecting the process thickness of the wafer surface, which is characterized by comprising a light source, a first light path, a second light path, a sampling frequency control unit, a photoelectric conversion unit and a calculation unit, wherein the The light source is used to provide incident light; the first optical path is used to transmit the incident light and radiate the incident light to the surface of the wafer; the second optical path includes a first branch and a second branch, which are used separately The interference light and the plasma reflected light are collected and transmitted to the photoelectric conversion unit. The interference light is the interference light formed by the reflected light reflected on the surface of the wafer and the incident light; the sampling frequency control unit is used to control the The first optical path, the first branch, and the second branch are turned on and off, so as to switch between turning on the first optical path and the first branch and turning on the second branch; the sampling frequency control unit also Used to adjust the switching frequency; the photoelectric conversion unit is used to convert the interference light and the plasma reflected light into electrical signals and send them to the calculation unit; the calculation unit is used to obtain light intensity data according to the electrical signals, The surface thickness of the wafer is calculated according to the light intensity data, and the online monitoring system further includes a filter element for filtering the incident light in the first optical path, the first branch The interference light in the path and the plasma reflected light in the second branch path allow the light of the specified wavelength to pass. The online monitoring system according to item 1 of the scope of patent application, wherein the sampling frequency control unit includes a diaphragm and a driving mechanism, wherein the sampling frequency control unit includes a diaphragm and a rotation mechanism for driving the diaphragm to rotate. A driving mechanism, wherein the diaphragm includes a barrier portion and an opening portion, and under the driving of the driving mechanism, the opening portion can rotate around the center of the barrier portion to correspond to the first optical path and the first branch path , To connect the first optical path and the first branch, and the barrier part rotates around the center of the barrier part to be opposite to the second branch Or, the opening is rotated around the center of the barrier to a position corresponding to the second branch to connect to the second branch, while the barrier The part rotates around the center of the barrier part to a position corresponding to the first light path and the first branch to disconnect the first light path and the first branch. The online monitoring system according to item 2 of the scope of patent application, wherein the online monitoring system further includes a light shielding tube, the first light path, the first branch and the second branch are all arranged in the light shielding tube, and The light transmission directions of the three are parallel to the axis of the light-shielding tube; and the first light path and the first branch are located on the same side of the axis of the light-shielding tube with respect to the axis of the light-shielding tube, and the second branch Located on the opposite side of the first optical path and the first branch; the diaphragm is arranged in the light shielding barrel, and the rotation axis of the diaphragm coincides with the axis of the light shielding barrel. The online monitoring system according to item 2 of the scope of patent application, wherein each of the first optical path, the first branch and the second branch includes a first part and a first part arranged at intervals along the respective light transmission direction. Two parts, wherein the first part is used for emitting light toward the second part; the second part is used for receiving the light; the diaphragm is arranged between the first part and the second part. The online monitoring system according to item 1 of the scope of patent application, wherein the sampling frequency control unit includes a power source for supplying power to the light source at a preset frequency, and the preset frequency of the power source is adjustable; the The photoelectric conversion unit includes a first subunit and a second subunit, which are respectively used to convert the interference light and the plasma reflected light into electrical signals; wherein the power source is triggered in synchronization with the first subunit; the The power supply triggers asynchronously with the second subunit. The online monitoring system according to any one of items 1 to 5 of the scope of patent application, wherein the photoelectric conversion unit includes a photomultiplier tube; By adjusting the voltage applied to the photomultiplier tube, the intensity of the interference light and the reflected light of the plasma can be adjusted. The online monitoring system according to item 1 of the scope of patent application, wherein the filter element includes a rotation axis and a plurality of filters of different wavelength bands arranged around the rotation axis, and the rotation axis is used to drive the plurality of filters The optical sheet rotates around the rotation axis, so that the three optical filters of designated wavelengths are respectively rotated to positions corresponding to the first optical path, the first branch and the second branch. According to the online monitoring system described in item 7 of the scope of patent application, the number of the filters is 8, and the center angle between two adjacent filters is 45°. The online monitoring system according to any one of items 1 to 5 of the scope of the patent application, wherein the online monitoring system further includes a lens arranged between the emitting end of the first optical path and the surface of the wafer, and Between the receiving end of the second optical path and the surface of the wafer, the incident light from the emitting end of the first optical path is divergently radiated to the surface of the wafer, and the reflected light is converged and radiated to the receiving end of the second optical path. end. A semiconductor processing device includes a reaction chamber in which a susceptor for carrying a wafer is arranged, and an upper electrode mechanism is arranged on the top of the reaction chamber, and is characterized in that it also includes the first The online monitoring system described in any one of items 1 to 9 is used to detect the process thickness of the wafer surface. The semiconductor processing device according to claim 10, wherein the online monitoring system further includes a lens arranged between the emitting end of the first optical path and the surface of the wafer and the receiving end of the second optical path Between the surface of the wafer and the surface of the wafer, it is used to radiate the incident light to the surface of the wafer while converging and radiating the reflected light to the receiving end of the second optical path; the output end of the first optical path and the input of the second optical path The end is located above the lens; the photoelectric conversion unit and the calculation unit are both located outside the reaction chamber. The semiconductor processing apparatus according to claim 11, wherein the upper electrode mechanism includes a dielectric window, the dielectric window is arranged above the base; the lens is arranged in the dielectric window , And located at the center position of the dielectric window, and the lens is exposed from the side of the dielectric window away from the base; or, the lens is arranged at the center position on the dielectric window, And it is located on the side away from the base.

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