Spectrum module and etching end point detection device and method

Abstract

The invention provides a spectrum module and an etching end point detection device and method.The spectrum module comprises a shell, a light inlet is formed in the shell, a diaphragm, a collimating mirror, an optical grating, a focusing mirror and a detector are arranged in the shell, the light inlet is used for being connected with an external optical fiber or enabling light to enter the shell, the diaphragm is used for receiving the light at the light inlet, and the collimating mirror is arranged on the shell; the collimating mirror is used for reflecting light from the diaphragm to the grating, the grating is used for reflecting light reflected by the collimating mirror to the focusing mirror, the focusing mirror is used for receiving reflected light from the grating and reflecting the reflected light to the detector, and a first light trap and a second light trap which are asymmetric are arranged on the shell between the focusing mirror and the detector. The first light trap is used for eliminating high-order diffracted light of the grating, the second light trap is used for eliminating scattered light of the focus lens towards the detector, stray light in the device is reduced, and the accuracy of weak light signal analysis in the etching process is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor manufacturing, and more specifically, relates to a spectrum module, an etching endpoint detection device and a method. Background Art

[0002] Spectrometer is the basic test equipment for spectral analysis. With the continuous development of modern science and technology, miniaturization, lightness, portability and high resolution have gradually become the mainstream trend of the development of spectral instruments.

[0003] Chinese patent CN217953673U discloses a miniature fiber optic spectrometer, including a housing, a slit, a collimator, a grating assembly, a focusing lens and a detector. The housing is provided with a fiber optic interface, the slit is arranged in the housing, and the slit is connected to the fiber optic interface, the collimator is movably arranged in the housing, and the collimator is located on the side opposite to the slit, the grating assembly includes a grating frame and a grating arranged on the grating frame, the grating frame is movably connected to the housing, the grating is used to receive the light reflected from the collimator, the focusing lens is arranged in the housing, the focusing lens and the grating are arranged oppositely, the detector is arranged on the housing, and the detector is used to receive the spectral image focused by the focusing lens. The working principle of the spectrometer is that the light beam entering from the slit is transformed into a parallel light beam through the collimator and then incident on the grating assembly of the dispersion element, and the composite light is decomposed into multiple monochromatic lights distributed according to the spatial law due to the diffraction effect of the grating assembly, and these monochromatic lights are then reflected to the detector through the focusing lens.

[0004] The spectrometer disclosed in the above patent can improve the efficiency of installation and debugging and realize the requirement of miniaturization of the spectrometer, but it does not disclose how to eliminate the stray light inside the spectrometer during use. In order to eliminate the stray light inside the spectrometer, technicians have disclosed the arrangement of a light baffle between the collimating lens and the imaging lens to reduce the stray light brought by the incident light beam and the side light from the collimating lens toward the focusing lens. However, the arrangement of the baffle will inevitably lead to the generation of reflected stray light inside the spectrometer, and the structure cannot eliminate the high-order diffraction light of the grating and the stray light reflected by the focusing lens, affecting the accuracy of the spectral analysis. Summary of the invention

[0005] The object of the present invention is to provide a spectrum module and an endpoint detection device, which can eliminate the high-order diffraction light of the grating and the stray light reflected by the focusing mirror, thereby improving the accuracy of the spectrum analysis of the spectrometer.

[0006] To achieve the above object, the technical solution adopted by the present invention is: the first aspect of the present invention provides a spectrum module, including a housing and a slit, an aperture, a collimator, a grating, a focusing lens and a detector arranged in the housing, wherein the housing is provided with a light inlet; The light inlet is used to connect an external optical fiber so that the incident light enters the interior of the housing; the slit and the aperture are used to limit the incident range of the incident light; the collimator is used to collimate the light entering from the aperture so that it becomes collimated light and is reflected to the grating; the grating is used for diffraction and spectroscopy, diffracting the light from the collimator at different wavelengths and angles to the focusing lens; the focusing lens is used to reflect the light reflected from the grating and focus it to the detector; An asymmetric first light trap and a second light trap are arranged on the shell between the focusing mirror and the detector. The first light trap is used to eliminate the high-order diffraction light of the grating, and the second light trap is used to eliminate the scattered light emitted from the focusing mirror toward the detector.

[0007] In one embodiment, the shell includes an upper shell and a lower shell arranged in parallel, the first light trap and the second light trap are both arranged on the side wall between the upper shell and the lower shell, the first light trap has a first curved side wall and a first plane side wall connected to the first curved side wall, the second light trap has a second curved side wall and a second plane side wall connected to the second curved side wall, the first plane side wall intersects with the second plane side wall, the first plane side wall and the second plane side wall are both perpendicular to the upper shell and the lower shell, the second plane side wall extends toward one side of the detector, and the first plane side wall extends toward one side of the focusing mirror.

[0008] In one embodiment, the working surface of the collimating mirror, the working surface of the grating, the working surface of the focusing mirror and the working surface of the detector are all perpendicular to the upper shell and the lower shell, the first plane side wall is inclined at an angle of 40 degrees toward the focusing mirror, and the second plane side wall is inclined at an angle of 50 degrees toward the detector; the collimating mirror is inclined at 9 degrees toward the grating, the grating is inclined at 11 degrees toward the collimating mirror, and the focusing mirror is inclined at 15.5 degrees toward the detector.

[0009] In one embodiment, the curvature of the first curved sidewall is greater than the curvature of the second curved sidewall.

[0010] In one embodiment, light absorbing materials are disposed on surfaces of the first curved side wall, the first planar side wall, the second curved side wall, and the second planar side wall.

[0011] In one embodiment, a baffle is arranged between the collimating lens and the focusing lens, and the baffle is used to prevent the light reflected by the collimating lens from scattering toward the focusing lens. A third light trap is arranged between the baffle and the focusing lens, and the third light trap is used to eliminate the high-order diffraction light of the grating. The second light trap is also used to eliminate the reflected light of the baffle.

[0012] In one embodiment, the first light trap, the second light trap and the third light trap are all integrally formed with the shell, or the first light trap is arranged on a first mounting member, the second light trap is arranged on a second mounting member, and the third light trap is arranged on a third mounting member, and the first mounting member, the second mounting member and the third mounting member are all detachably connected to the shell.

[0013] In one embodiment, a sawtooth structure is provided inside the housing corresponding to the light path direction of the aperture and the collimator, and the sawtooth structure is used to eliminate stray light from the aperture toward the collimator.

[0014] In one embodiment, the sawtooth structure is integrally formed with the shell, or the sawtooth structure is detachably mounted on the shell.

[0015] In one embodiment, a light absorbing material is disposed on a side of the sawtooth structure facing away from the housing.

[0016] In one embodiment, a filter is provided on the optical path between the focusing lens and the detector.

[0017] A second aspect of the present invention provides an etching endpoint detection device, comprising the spectral module as described above.

[0018] A third aspect of the present invention provides an etching endpoint detection method, wherein the etching endpoint detection method uses the etching endpoint detection device as described above for detection, and the method comprises: During the etching process, the optical signal emitted by the chamber of the machine enters the etching endpoint detection device through the optical fiber; The etching endpoint detection device transmits the optical signal through the spectral module and eliminates the system stray light, and outputs an electrical signal; The electrical signal is processed by an algorithm, and the intensity change of the characteristic spectrum is detected to perform etching endpoint detection.

[0019] In one embodiment, the etching process aperture ratio in the chamber of the machine is in the range of 0.1%-100%, and the optical signal intensity is in the range of 100-3000.

[0020] The spectrum module provided by the present invention includes a shell and a slit, an aperture, a collimator, a grating, a focusing mirror and a detector arranged in the shell. The shell is provided with a light inlet, the light inlet is used to connect an external optical fiber or allow light to enter the interior of the shell, the aperture is used to receive light at the light inlet, the collimator is used to reflect light from the aperture to the grating, the grating is used to reflect light reflected from the collimator to the focusing mirror, the focusing mirror is used to receive reflected light from the grating and reflect the reflected light to the detector, and an asymmetric first light trap and a second light trap are arranged on the shell between the focusing mirror and the detector. The first light trap is used to eliminate high-order diffraction light of the grating, and the second light trap is used to eliminate scattered light from the focusing mirror toward the detector. The spectrum module is provided with an asymmetric first light trap and a second light trap on the shell between the focusing mirror and the detector. The first light trap can eliminate high-order diffraction light of the grating, and the second light trap can eliminate scattered light from the focusing mirror toward the detector. The spectrum module reduces stray light inside the device and improves the accuracy of weak light signal analysis.

[0021] The etching endpoint detection device provided by the present invention includes the above-mentioned spectral module, and an asymmetric first light trap and a second light trap are arranged on the shell between the focusing mirror and the detector of the spectral module. The first light trap is used to eliminate the high-order diffraction light of the grating, and the second light trap is used to eliminate the scattered light from the focusing mirror toward the detector. The spectral module is provided with an asymmetric first light trap and a second light trap on the shell between the focusing mirror and the detector. The first light trap can eliminate the high-order diffraction light of the grating, and the second light trap can eliminate the scattered light from the focusing mirror toward the detector. The spectral module reduces the stray light inside the device and improves the accuracy of the weak light signal analysis. The endpoint detection device with the above-mentioned spectral module can process and analyze the characteristic spectrum of plasma.

[0022] The etching endpoint detection method provided by the present invention adopts the above-mentioned etching endpoint detection device. The spectral module reduces the stray light on the internal optical path during the etching endpoint detection process, improves the measurement accuracy during the etching endpoint detection process and the accuracy of the spectral analysis, can accurately judge the etching endpoint of the plasma etching process, prevent over-etching or under-etching, ensure that the etching depth error is within the standard range, and improve the chip yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic diagram of the structure of a spectrum module provided by an embodiment of the present invention; Figure 2 A light path diagram provided for an embodiment of the present invention; Figure 3 A schematic diagram of the inclination angles of the first plane sidewall of the first light trap and the second plane sidewall of the second light trap in the spectral module provided in an embodiment of the present invention and the corresponding extinction regions. Green represents the high-order diffracted light reflected by the grating eliminated by the first light trap, yellow represents the scattered light emitted by the focusing mirror toward the detector eliminated by the second light trap, purple represents the high-order diffracted light reflected by the grating eliminated by the third light trap, blue represents the stray light eliminated by the sawtooth structure, and red represents the stray light blocked by the baffle; Figure 4 A light intensity-time curve diagram for TSV bosch process provided by an embodiment of the present invention; Figure 5 A light intensity-time curve diagram for an ON etch process provided by an embodiment of the present invention; Figure 6 A light intensity-time curve diagram for free radical process provided by an embodiment of the present invention.

[0025] Among them, the reference numerals in the figure are: 1. Spectral module; 11. Shell; 111. Light inlet; 112. Slit; 113. Diaphragm; 114. Collimator; 115. Grating; 116. Focusing lens; 117. Detector; 118. First light trap; 119. Second light trap; 120. Lower shell; 121. First side wall; 122. Second side wall; 123. Third side wall; 124. Fourth side wall; 125. Baffle; 126. Third light trap; 127. Sawtooth structure; 128. Filter. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "including" and "having" and any variations thereof used herein are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0028] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. It should be understood that the term "and / or" used in this article is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0030] The spectral module and etching endpoint detection device and method provided by the present invention are described in detail below in conjunction with specific embodiments.

[0031] Figure 1 A schematic diagram of the structure of a spectrum module provided in an embodiment of the present invention, Figure 2 For the optical path diagram provided by the embodiment of the present invention, please refer to Figure 1 , Figure 2 A first aspect of an embodiment of the present invention provides a spectral module 1, including a shell 11 and a slit 112, an aperture 113, a collimator 114, a grating 115, a focusing lens 116 and a detector 117 arranged in the shell, and a light inlet 111 is arranged on the shell 11.

[0032] The light inlet 111 is used to connect an external optical fiber so that the incident light enters the interior of the housing 11. The slit 112 and the aperture 113 are used to limit the incident range of the incident light. The collimator 114 is used to collimate the light entering from the aperture 113 to make it collimated light and reflect it to the grating 115. The grating 115 is used for diffraction and spectroscopy to diffract the light from the collimator 114 at different wavelengths and angles to the focusing lens 116. The focusing lens 116 is used to reflect the light reflected from the grating 115 and focus it on the detector 117.

[0033] An asymmetric first light trap 118 and a second light trap 119 are arranged on the housing 11 between the focusing mirror 116 and the detector 117. The first light trap 118 is used to eliminate the high-order diffraction light of the grating 115, and the second light trap 119 is used to eliminate the scattered light emitted from the focusing mirror 116 to the detector 117.

[0034] The housing 11 of this embodiment is a mounting carrier for the slit 112, the aperture 113, the collimator 114, the grating 115, the focusing lens 116 and the detector 117. This embodiment does not particularly limit the size and material of the housing 11. For example, the housing 11 of this embodiment is made of metal, which can increase the service life of the spectrum module. For example, when the spectrum module 1 of this embodiment is applied to the etching endpoint detection system, the optical signal is introduced into the interior of the spectrum module 1 through the optical fiber connected to the light inlet 111.

[0035] The slit 112, aperture 113, collimator 114, grating 115, focusing lens 116 and detector 117 in the optical module of this embodiment play a key role in the high-precision endpoint detection system. The specific functions are as follows: Slit 112: The function of slit 112 is to limit the width of the incident light so that only light along a specific direction can pass through, so that an image of the right size can be obtained when the final image is formed, which is crucial for improving the spectral resolution. Aperture 113: Aperture 113 is used to block stray light and constrain the beam size, thereby improving the signal-to-noise ratio. It helps to reduce unnecessary background light interference and ensure the accuracy of the analysis. Collimator 114: In the beam transmission system, the collimator 114 makes the light beam passing through the slit and the aperture become collimated light, which is the basis for subsequent dispersion and spectrometry. Grating 115, grating 115 can be a diffraction grating, which can disperse according to the wavelength of light. When light passes through grating 115, light of different wavelengths will be diffracted at different angles, thereby achieving wavelength separation. Focusing mirror 116: Focusing mirror 116 is located after grating 115. Its function is to converge the light beam dispersed by grating 115 to form a focal plane. This process is necessary to accurately map light of different wavelengths onto the detector to ensure that the spatial distribution of spectral information can be correctly collected.

[0036] In summary, the slit 112, aperture 113, collimator 114, grating 115, focusing mirror 116 and detector 117 work together to ensure that the optical signal can be effectively separated, focused and transmitted to the CMOS detector 117, thereby achieving high-precision analysis of the specific spectrum and accurately detecting the etching endpoint.

[0037] In this embodiment, an asymmetric first light trap and a second light trap are arranged on the housing between the focusing mirror and the detector, the first light trap is used to eliminate the high-order diffraction light of the grating, and the second light trap is used to eliminate the scattered light from the focusing mirror to the detector. The spectrum module is provided with an asymmetric first light trap and a second light trap on the housing between the focusing mirror and the detector, the first light trap can eliminate the high-order diffraction light of the grating, and the second light trap can eliminate the scattered light from the focusing mirror to the detector. The spectrum module reduces the stray light inside the device and improves the accuracy of the weak light signal analysis. The endpoint detection device with the above spectrum module can process and analyze the characteristic spectrum of plasma.

[0038] In a specific embodiment, the housing 11 includes an upper housing (not shown in the figure), a lower housing 120 and side walls perpendicular to the upper housing and the lower housing, and the upper housing, the lower housing 120 and the side walls enclose a receiving space. Exemplarily, the side walls of this embodiment include a first side wall 121, a second side wall 122, a third side wall 123 and a fourth side wall 124 connected in sequence, and the first side wall 121, the second side wall 122, the third side wall 123 and the fourth side wall 124 enclose a square receiving space. In this embodiment, the light entrance 111, the slit 112, the aperture 113 and the grating 115 are installed on the first side wall 121, the collimating mirror 114 and the focusing mirror 116 are installed on the third side wall 123, and the first light trap 118 and the second light trap 119 are both arranged on the third side wall 123. The first light trap 118 has a first curved side wall and a first plane side wall connected to the first curved side wall, and the second light trap 119 has a second curved side wall and a second plane side wall connected to the second curved side wall. The first plane side wall intersects with the second plane side wall, and the first plane side wall and the second plane side wall are both perpendicular to the upper shell and the lower shell 120. The second plane side wall extends toward the detector 117, and the first plane side wall extends toward the focusing mirror 116.

[0039] The first light trap 118 of the present embodiment includes a first curved side wall and a first plane side wall connected to the first curved side wall, the first plane side wall extends toward the side of the focusing mirror, and can eliminate the high-order diffraction light of the grating to a greater extent. The second light trap 119 of the present embodiment includes a second curved side wall and a second plane side wall connected to the second curved side wall, the second plane side wall extends toward the side of the detector, and the second light trap can eliminate the scattered light from the focusing mirror toward the detector to a greater extent. The first plane side wall and the second plane side wall of the present embodiment intersect in a straight line, which can reduce the volume of the spectral module to a certain extent. The first light trap and the second light trap of the present embodiment are arranged asymmetrically, the first light trap is mainly used to eliminate the high-order diffraction light of the grating, and the second light trap is mainly used to eliminate the scattered light from the focusing mirror toward the detector.

[0040] Figure 3 For a schematic diagram of the inclination angles of the first plane sidewall of the first light trap and the second plane sidewall of the second light trap and the corresponding extinction regions in the spectral module provided in an embodiment of the present invention, please refer to Figure 3 In a specific embodiment, the working surface of the collimating mirror 114, the working surface of the grating 115, the working surface of the focusing mirror 116 and the working surface of the detector 117 are all perpendicular to the upper shell and the lower shell 120, the first plane side wall is inclined at an angle of 40 degrees toward the side of the focusing mirror 116, and the second plane side wall is inclined at an angle of 50 degrees toward the detector 117; the collimating mirror 114 is inclined at 9 degrees toward the grating 115, the grating 115 is inclined at 11 degrees toward the collimating mirror 114, and the focusing mirror 116 is inclined at 15.5 degrees toward the detector 117.

[0041] In this embodiment, the optical path design uses a focal length of 70 mm, the distance from the slit 112 to the focusing mirror 116 is 70 mm, the collimator 114 is inclined at 9 degrees toward the grating 115, the incident light entering from the aperture 113 is reflected by the collimator 114 and hits the surface of the grating 115, the grating 115 is inclined at 11 degrees toward the collimator 114, the focusing mirror 116 is inclined at 15.5 degrees toward the detector 117, and the second-order diffraction light of the grating 115 hits the fourth side wall 124 at an angle of 50 degrees to the fourth side wall 124. The first plane side wall of this embodiment is inclined at an angle of 40 degrees toward the focusing mirror side. When the second-order diffraction light of the grating 115 hits the fourth side wall 124 at an angle of 50 degrees to the fourth side wall 124, the second-order diffraction light can enter the first light trap 118 to the maximum extent, so that the first light trap 118 can absorb the second-order diffraction light to the maximum extent. In this embodiment, the central wavelength light beam is reflected by the focusing mirror and then directed to the fourth side wall 124 at 40 degrees. The second plane side wall is inclined toward the detector at an angle of 50 degrees, which can eliminate scattered light from the focusing mirror 116 toward the detector 117 to a greater extent. Figure 3 Different colors are used to illustrate the elimination path of stray light. Yellow represents the scattered light emitted from the focusing mirror 116 to the detector 117 eliminated by the second light trap 119, and green represents the high-order diffraction light reflected by the grating 115 eliminated by the first light trap 118.

[0042] Further, the curvature of the first curved side wall is greater than the curvature of the second curved side wall. The curvature of the first curved side wall of the first light trap 118 of this embodiment is greater than the curvature of the second curved side wall of the second light trap 119, so that the width of the first light trap 118 is greater than the width of the second light trap 119. The first light trap 118 of this embodiment eliminates the second-order diffracted light directly diffracted from the grating 115. Since the second-order diffracted light directly diffracted by the grating 115 is not focused and has a larger width, the width of the first light trap 118 of this embodiment is greater than the width of the second light trap 119, which can better prevent the second-order diffracted light directly diffracted by the grating 115 from being reflected by the fourth side wall 124 and re-entering the light path.

[0043] Furthermore, the surfaces of the first curved sidewall, the first plane sidewall, the second curved sidewall, and the second plane sidewall are all provided with light absorbing materials. In this embodiment, by providing light absorbing materials on the surfaces of the first curved sidewall, the first plane sidewall, the second curved sidewall, and the second plane sidewall, the extinction effect of the first light trap 118 and the second light trap 119 is further improved. The light absorbing materials in this embodiment are light absorbing materials in the prior art, and are not specifically described in this embodiment.

[0044] In one specific embodiment, see Figure 3 A baffle 125 is provided between the collimator 114 and the focusing mirror 116, and the baffle 125 is used to prevent the light reflected by the collimator 114 from scattering toward the focusing mirror 116. A third light trap 126 is provided between the baffle 125 and the focusing mirror 116, and the third light trap 126 is used to eliminate the high-order diffraction light of the grating 115. The second light trap 119 is also used to eliminate the reflected light of the baffle 125. In this embodiment, by providing the baffle 125 between the collimator 114 and the focusing mirror 116, the baffle 125 can block the light reflected by the collimator 114 from irradiating to the side of the focusing mirror 116, and the baffle 125 can also block the light reflected by the collimator 114 from irradiating to the fourth side wall 124 to generate reflected stray light. A third light trap 126 is provided between the baffle 125 and the focusing mirror 116 of this embodiment. The third light trap 126 of this embodiment can eliminate the high-order diffraction light reflected by the grating 115 to the focusing mirror 116 on the side close to the collimating mirror 114. The second light trap 119 of this embodiment can also eliminate the reflected light from the baffle 125 toward the fourth side wall 124. The spectrum module 1 further reduces the stray light on the internal optical path, further improving the measurement accuracy of the spectrum module 1 and the accuracy of the spectrum analysis. Figure 3 The medium purple color represents the high-order diffracted light reflected by the grating 115 eliminated by the third light trap 126 , and the red color represents the stray light toward the focusing mirror 116 blocked by the baffle 125 .

[0045] Optionally, the first light trap 118, the second light trap 119 and the third light trap 126 are all integrally formed with the shell, or the first light trap 118 is arranged on a first mounting member, the second light trap 119 is arranged on a second mounting member, and the third light trap 126 is arranged on a third mounting member, and the first mounting member, the second mounting member and the third mounting member are all detachably connected to the shell.

[0046] The first light trap 118, the second light trap 119 and the third light trap 126 of this embodiment can be integrally formed with the shell. This molding method can save production time and material consumption. It can reduce the failure rate caused by loose or damaged parts and improve the overall stability of the product. Of course, in other embodiments, the first light trap 118, the second light trap 119 and the third light trap 126 can be designed to be detachably connected to the shell. For example, the first light trap 118 is set on the first mounting member, the second light trap 119 is set on the second mounting member, and the third light trap 126 is set on the third mounting member. The first mounting member, the second mounting member, and the third mounting member are detachably connected to the shell, making the first light trap 118, the second light trap 119 and the third light trap 126 easier to maintain and convenient to replace parts as needed. ‌‌

[0047] Furthermore, a sawtooth structure 127 is provided on the second side wall 122 of the housing 11 corresponding to the optical path direction of the aperture 113 and the collimator 114, and the sawtooth structure 127 is used to eliminate stray light from the aperture 113 toward the collimator 114. In this embodiment, by providing the sawtooth structure 127 inside the housing corresponding to the optical path direction of the aperture 113 and the collimator 114, the sawtooth structure 127 can largely eliminate the stray light that enters from the aperture 113 and is projected onto the second side wall 122, and the sawtooth structure 127 can eliminate the reflected light from the collimator 114, the grating 115, the focusing lens 116 and the detector 117 inside the housing 11 toward the second side wall 122, that is, the reflected stray light of the internal parts of the instrument. Figure 3 In the figure, blue represents the stray light reflected by the collimator 114 toward the second side wall 122 which is eliminated by the sawtooth structure 127 .

[0048] Optionally, the sawtooth structure 127 is integrally formed with the housing 11, or the sawtooth structure 127 is detachably mounted on the housing 11. Exemplarily, the sawtooth structure 127 of this embodiment is integrally formed with the housing 11, and the manufacturing method is simple. Of course, in other embodiments, the sawtooth structure 127 can be detachably connected to the housing 11.

[0049] Furthermore, a light absorbing material is provided on the side of the sawtooth structure 127 away from the housing in this embodiment. By providing the light absorbing material on the side of the sawtooth structure 127 away from the housing, stray light incident toward the second side wall 122 can be better eliminated. The light absorbing material in this embodiment is a light absorbing material in the prior art.

[0050] Furthermore, a filter 128 is provided on the optical path between the focusing lens 116 and the detector 117. The filter 128 is used to selectively transmit light of certain wavelengths while blocking other wavelengths.

[0051] The spectral module of an embodiment of the present invention includes a shell and a slit, an aperture, a collimator, a grating, a focusing mirror and a detector arranged in the shell. The shell is provided with a light inlet, the light inlet is used to connect an external optical fiber or allow light to enter the interior of the shell, the aperture is used to receive light at the light inlet, the collimator is used to reflect light from the aperture to the grating, the grating is used to reflect light reflected from the collimator to the focusing mirror, the focusing mirror is used to receive reflected light from the grating and reflect the reflected light to the detector, and an asymmetric first light trap and a second light trap are arranged on the shell between the focusing mirror and the detector. The first light trap is used to eliminate high-order diffraction light of the grating, and the second light trap is used to eliminate scattered light from the focusing mirror toward the detector. The spectral module is provided with an asymmetric first light trap and a second light trap on the shell between the focusing mirror and the detector. The first light trap can eliminate high-order diffraction light of the grating, and the second light trap can eliminate scattered light from the focusing mirror toward the detector. The spectral module reduces stray light inside the device and improves the accuracy of weak light signal analysis.

[0052] A second aspect of the embodiments of the present invention provides an etching endpoint detection device, comprising the spectral module as described in the above embodiments.

[0053] For example, the spectrum module includes a shell and a slit, an aperture, a collimator, a grating, a focusing lens and a detector arranged in the shell, and a light inlet is arranged on the shell.

[0054] The light inlet is used to connect an external optical fiber so that the incident light enters the interior of the housing; the slit and the aperture are used to limit the incident range of the incident light; the collimator is used to collimate the light entering from the aperture so that it becomes collimated light and is reflected to the grating; the grating is used for diffraction and spectroscopy, diffracting the light from the collimator at different wavelengths and angles to the focusing lens; the focusing lens is used to reflect the light reflected from the grating and focus it to the detector.

[0055] An asymmetric first light trap and a second light trap are arranged on the shell between the focusing mirror and the detector. The first light trap is used to eliminate the high-order diffraction light of the grating, and the second light trap is used to eliminate the scattered light emitted from the focusing mirror toward the detector.

[0056] The etching endpoint detection device provided by the embodiment of the present invention includes the above-mentioned spectral module, and an asymmetric first light trap and a second light trap are arranged on the shell between the focusing mirror and the detector of the spectral module. The first light trap is used to eliminate the high-order diffraction light of the grating, and the second light trap is used to eliminate the scattered light from the focusing mirror toward the detector. The spectral module is provided with an asymmetric first light trap and a second light trap on the shell between the focusing mirror and the detector. The first light trap can eliminate the high-order diffraction light of the grating, and the second light trap can eliminate the scattered light from the focusing mirror toward the detector. The spectral module reduces the stray light inside the device and improves the accuracy of the weak light signal analysis. The endpoint detection device with the above-mentioned spectral module can process and analyze the characteristic spectrum of plasma.

[0057] The etching endpoint detection device of this embodiment can be used to collect and process the optical signal generated by the etching process. For example, the etching endpoint detection device is connected to the machine chamber via an optical fiber, and the optical fiber is used to obtain the optical signal inside the machine chamber and transmit it to the etching endpoint detection device. The optical fiber is arranged beside the observation window of the machine chamber to facilitate the collection of the optical signal in the machine chamber.

[0058] The etching endpoint detection device provided by the embodiment of the present invention includes the above-mentioned spectral module, and an asymmetric first light trap and a second light trap are arranged on the shell between the focusing mirror and the detector of the spectral module. The first light trap is used to eliminate the high-order diffraction light of the grating, and the second light trap is used to eliminate the scattered light from the focusing mirror toward the detector. The spectral module is provided with an asymmetric first light trap and a second light trap on the shell between the focusing mirror and the detector. The first light trap can eliminate the high-order diffraction light of the grating, and the second light trap can eliminate the scattered light from the focusing mirror toward the detector. The spectral module reduces the stray light inside the device and improves the accuracy of the weak light signal analysis. The endpoint detection device with the above-mentioned spectral module can process and analyze the characteristic spectrum of plasma.

[0059] A third aspect of an embodiment of the present invention provides an etching endpoint detection method, wherein the etching endpoint detection method uses the etching endpoint detection device as described above for detection.

[0060] The method comprises: S101, during the etching process, the optical signal emitted by the chamber of the machine enters the etching endpoint detection device through the optical fiber.

[0061] Specifically, the machine chamber and the light inlet of the spectrum module of the endpoint detection device are connected through an optical fiber, so that the optical signal emitted by the machine chamber during the etching process enters the spectrum module through the optical fiber.

[0062] S102, the etching endpoint detection device transmits the optical signal through the spectral module and eliminates system stray light, and outputs an electrical signal.

[0063] Specifically, after the optical signal enters the spectrum module through the light inlet, the incident range of the incident light is adjusted by the slit and the aperture, and then the optical signal is collimated and reflected by the collimator to enter the grating. The grating diffracts and splits the light from the collimator, and diffracts the light incident from the collimator to the focusing mirror at different wavelengths and angles. The focusing mirror reflects the light reflected from the grating and focuses it on the detector. During the transmission of the optical signal, the baffle between the collimator and the focusing mirror can block the light reflected from the collimator from irradiating the focusing mirror. The baffle can also block the light reflected from the collimator from irradiating the side wall to generate reflected stray light. The first light trap on the shell between the focusing mirror and the detector and the third light trap between the baffle and the focusing mirror can eliminate the high-order diffraction light of the grating. The second light trap on the shell between the focusing mirror and the detector can eliminate the scattered light emitted from the focusing mirror to the detector. The spectral module of the etching endpoint detection device in this embodiment can reduce the stray light of the incident light signal on the internal optical path, improve the signal-to-noise ratio, and improve the accuracy of spectral analysis. When the light signal is a weak signal, the endpoint detection device can still accurately determine the etching endpoint of the plasma etching process, prevent over-etching or under-etching, ensure that the etching depth error is within the standard range, and improve the chip yield.

[0064] S103, processing the electrical signal through an algorithm, detecting the intensity change of the characteristic spectrum, so as to perform etching endpoint detection.

[0065] Specifically, after the optical signal is transmitted through the spectral module and the system stray light is eliminated, the electrical signal output by the spectral module detector is analyzed, and the etching endpoint is detected through the change in the characteristic spectrum intensity.

[0066] Exemplarily, in the above embodiment, the etching process aperture ratio in the chamber of the machine is in the range of 0.1%-100%, and the optical signal strength is 10-3000. The aperture ratio includes 0.1% and 100%, and any value between 0.1%-100%, and the optical signal strength includes 10 and 3000, and any value between 10-3000.

[0067] The etching endpoint detection method of this embodiment can be applied to a TSV bosch etching process, an ON-etch process or a free radical detection process.

[0068] Exemplarily, the etching endpoint detection method of this embodiment is applied to the TSV Bosch process, and the etching hole opening rate is 0.5%. This embodiment is based on the above-mentioned etching endpoint detection device, and performs TSV Bosch process etching endpoint detection through the etching endpoint detection method. During the TSV Bosch process, plasma is generated during the etching process in the etching chamber, and then the light emitted by the plasma enters the device through the optical fiber. Figure 4 As shown, the TSV bosch process etching process alternately etches silicon and polysilicon materials to form an etching curve of the light intensity signal. It is necessary to detect the light intensity change curve corresponding to the characteristic plasma-CO. The characteristic plasma-CO light signal intensity received by the light input port of the spectral module is about 800. After periodic etching, the etching end point is reached around 320s. The spectral module of the etching end point detection device of this embodiment can reduce the stray light of the incident light signal on the internal optical path, improve the signal-to-noise ratio, and improve the accuracy of spectral analysis. In the environment of weak light signals, the end point detection device can still accurately determine the etching end point of the TSV bosch process, prevent over-etching or under-etching, ensure that the error of the etched depth is within the standard range, and improve the yield of the chip.

[0069] Exemplarily, the etching endpoint detection method of this embodiment is applied to the ON etch process, and the etching groove opening rate is 0.1%. Based on the above-mentioned etching endpoint detection device, this embodiment performs etching endpoint detection of the ON etch process through the etching endpoint detection method. During the ON etch process, plasma is generated during the etching process in the etching chamber, and then the light emitted by the plasma enters the device through the optical fiber. Figure 5 As shown, the ON-etch process involves alternating etching of oxide and nitride materials, and the light intensity change curve corresponding to the characteristic plasma-N needs to be detected. The characteristic plasma-N light signal intensity received by the light input port of the spectral module is about 500, and the etching end point is reached around 95s after periodic etching. The spectral module of the etching end point detection device of this embodiment can reduce the stray light of the incident light signal on the internal optical path, improve the signal-to-noise ratio, and improve the accuracy of spectral analysis. In the environment of weak light signals, the end point detection device can still accurately determine the etching end point of the ON etch process, prevent over-etching or under-etching, ensure that the etched depth error is within the standard range, and improve the yield of the chip.

[0070] Exemplarily, the etching endpoint detection method of this embodiment is applied to a free radical process, which is a non-patterned blanket full aperture etching. This embodiment is based on the above-mentioned etching endpoint detection device, and performs free radical process etching endpoint detection through an etching endpoint detection method. During the free radical process, plasma is generated during the etching process in the etching chamber, and then the light emitted by the plasma enters the device through the optical fiber. Figure 6As shown, the free process etching process involves the etching of titanium nitride material, and the light intensity change curve corresponding to the characteristic plasma-N2 needs to be detected. The characteristic plasma-N2 light signal intensity received by the light input port of the spectral module is about 200, and the etching end point is reached around 70s after periodic etching. The spectral module of the etching end point detection device of this embodiment can reduce the stray light of the incident light signal in the internal optical path, improve the signal-to-noise ratio, and improve the accuracy of spectral analysis. In the environment of weak light signals, the end point detection device can still accurately determine the etching end point of the free radical process, prevent over-etching or under-etching, ensure that the error of the etched depth is within the standard range, and improve the yield of the chip.

[0071] The present invention is particularly suitable for etching endpoint detection with weak optical signals. The semiconductor industry generally believes that optical signals below 3000 are weak optical signals, which can effectively prevent optical signals from being masked by stray signals.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A spectrum module, characterized in that: It comprises a shell and a slit, an aperture, a collimator, a grating, a focusing lens and a detector arranged in the shell, and a light inlet is arranged on the shell; The light inlet is used to connect an external optical fiber so that the incident light enters the interior of the housing; the slit and the aperture are used to limit the incident range of the incident light; the collimator is used to collimate the light entering from the aperture so that it becomes collimated light and is reflected to the grating; the grating is used for diffraction and spectroscopy, diffracting the light from the collimator at different wavelengths and angles to the focusing lens; the focusing lens is used to reflect the light reflected from the grating and focus it to the detector; An asymmetric first light trap and a second light trap are arranged on the shell between the focusing mirror and the detector. The first light trap is used to eliminate the high-order diffraction light of the grating, and the second light trap is used to eliminate the scattered light emitted from the focusing mirror toward the detector.

2. The spectrum module according to claim 1, characterized in that: The shell includes an upper shell and a lower shell arranged in parallel, the first light trap and the second light trap are both arranged on the side wall between the upper shell and the lower shell, the first light trap has a first curved side wall and a first planar side wall connected to the first curved side wall, the second light trap has a second curved side wall and a second planar side wall connected to the second curved side wall, the first planar side wall intersects with the second planar side wall, the first planar side wall and the second planar side wall are both perpendicular to the upper shell and the lower shell, the second planar side wall extends toward one side of the detector, and the first planar side wall extends toward one side of the focusing mirror.

3. The spectrum module according to claim 2, characterized in that: The working surfaces of the collimating mirror, the grating, the focusing mirror and the detector are all perpendicular to the upper shell and the lower shell, the first plane side wall is inclined at an angle of 40 degrees toward the focusing mirror, and the second plane side wall is inclined at an angle of 50 degrees toward the detector; the collimating mirror is inclined at 9 degrees toward the grating, the grating is inclined at 11 degrees toward the collimating mirror, and the focusing mirror is inclined at 15.5 degrees toward the detector.

4. The spectrum module according to claim 2, characterized in that: The curvature of the first curved side wall is greater than the curvature of the second curved side wall.

5. The spectrum module according to claim 2, characterized in that: Light absorbing materials are disposed on surfaces of the first curved side wall, the first planar side wall, the second curved side wall, and the second planar side wall.

6. The spectrum module according to claim 1, characterized in that: A baffle is arranged between the collimating lens and the focusing lens, and the baffle is used to prevent the light reflected by the collimating lens from scattering toward the focusing lens. A third light trap is arranged between the baffle and the focusing lens, and the third light trap is used to eliminate the high-order diffraction light of the grating. The second light trap is also used to eliminate the reflected light from the baffle.

7. The spectrum module according to claim 6, characterized in that: The first light trap, the second light trap and the third light trap are all integrally formed with the shell, or the first light trap is arranged on a first mounting member, the second light trap is arranged on a second mounting member, and the third light trap is arranged on a third mounting member, and the first mounting member, the second mounting member and the third mounting member are all detachably connected to the shell.

8. The spectrum module according to any one of claims 1 to 7, characterized in that: A sawtooth structure is provided inside the housing corresponding to the diaphragm and the collimator in the optical path direction, and the sawtooth structure is used to eliminate stray light from the diaphragm toward the collimator.

9. The spectrum module according to claim 8, characterized in that: The sawtooth structure is integrally formed with the shell, or the sawtooth structure is detachably mounted on the shell.

10. The spectrum module according to claim 8, characterized in that: A light absorbing material is disposed on a side of the sawtooth structure facing away from the housing.

11. The spectrum module according to claim 8, characterized in that: A filter is arranged on the optical path between the focusing mirror and the detector.

12. An etching endpoint detection device, characterized in that: It comprises a spectral module as described in any one of claims 1 to 11 above.

13. A method for detecting an etching endpoint, characterized in that: The etching endpoint detection method adopts the etching endpoint detection device according to claim 12 for detection, and the method comprises: During the etching process, the optical signal emitted by the chamber of the machine enters the etching endpoint detection device through the optical fiber; The etching endpoint detection device transmits the optical signal through the spectral module and eliminates the system stray light, and outputs an electrical signal; The electrical signal is processed by an algorithm, and the intensity change of the characteristic spectrum is detected to perform etching endpoint detection.

14. The etching endpoint detection method according to claim 13, characterized in that: The etching process opening rate in the machine chamber ranges from 0.1% to 100%, and the optical signal intensity is 100-3000.

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