Stress monitoring system and method and furnace tube equipment

Abstract

The invention provides a stress monitoring system, a stress monitoring method and furnace tube equipment, the system comprises a light emitter, a light incoming optical fiber, a first light outgoing optical fiber, a Raman probe, a photoelectric detector and a processor, and the outgoing direction and the vertical height of the light incoming optical fiber are adjustable; the light emitter is used for providing a first light beam, and the wavelength of the first light beam provided by the light emitter is adjustable; the incident optical fiber is used for enabling the first light beam to enter a target measurement area of the wafer to be measured; the first light-emitting optical fiber is used for collecting scattered light formed in a target measurement area; the Raman probe is used for extracting a Raman scattering light signal from the scattering light; the photoelectric detector is used for converting the Raman scattering light signal into a corresponding Raman scattering electric signal; and the processor is used for acquiring stress information of the target measurement area according to the Raman scattering electric signal. According to the invention, nondestructive monitoring of the residual stress of the wafer in a high-temperature state can be realized, and real-time monitoring of the residual stress of the wafer at different depths can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor processing and manufacturing, and in particular to a stress monitoring system, a stress monitoring method and a furnace tube device. Background Art

[0002] Residual stress is an important factor affecting the performance and reliability of semiconductor devices. Residual stress can lead to the nucleation and development of dislocations, which in turn leads to the formation of voids and cracks. For example, in DRAM (dynamic random access memory) capacitor devices, during the annealing process of SIN (silicon nitride) as a dielectric layer, the high stress caused by the regrowth of polysilicon grains may cause the cracking of the SIN film. In the process of high-temperature furnace tubes, due to the influence of thermal stress, the silicon substrate will be locally lattice distorted, which will induce lattice dislocations, lattice slips, etc., and even cause local deformation, which will not only affect the performance and reliability of the device, but also affect the normal progress of subsequent processes. For example, in the CMP (chemical mechanical polishing) process of STI-HDP (shallow trench isolation-high density plasma) with SIN as the stop layer, due to the local deformation of the silicon wafer caused by STI-ANN (shallow trench isolation-annealing), oxide (oxide residue) residues (local depressions) or SIN damage (local protrusions) in the local area will result in device failure. Currently, stress measurement mainly adopts post-monitoring, and real-time monitoring is impossible.

[0003] It should be noted that the information disclosed in the background technology section of the invention is only intended to deepen the understanding of the general background technology of the invention, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0004] The purpose of the present invention is to provide a stress monitoring system, a stress monitoring method and a furnace tube device, which can not only realize non-destructive monitoring of residual stress of wafers under high temperature conditions, but also realize real-time monitoring of residual stress at different depths of wafers.

[0005] To achieve the above-mentioned purpose, the present invention provides a stress monitoring system, which includes an optical transmitter, an input optical fiber, a first output optical fiber, a Raman probe, a photodetector and a processor, wherein the output direction of the input optical fiber and the vertical height of the input optical fiber are both adjustable; the optical transmitter is used to provide a first light beam, and the wavelength of the first light beam provided by the optical transmitter is adjustable; the input optical fiber is used to inject the first light beam into a target measurement area of ​​a wafer to be measured, so that the first light beam is scattered in the target measurement area; the first output optical fiber is used to collect the scattered light formed in the target measurement area and transmit it to the Raman probe; the Raman probe is used to extract a Raman scattered light signal from the scattered light and transmit it to the photodetector; the photodetector is used to convert the Raman scattered light signal into a corresponding Raman scattered electrical signal and transmit it to the processor; the processor is used to obtain stress information of the target measurement area according to the Raman scattered electrical signal.

[0006] Optionally, the processor is further used to: obtain first Raman shift information corresponding to the target measurement area according to the Raman scattering electrical signal; obtain relative Raman shift information corresponding to the target measurement area according to the first Raman shift information and pre-acquired second Raman shift information corresponding to the target measurement area at an initial moment; obtain relative stress information of the target measurement area according to the relative Raman shift information corresponding to the target measurement area and pre-acquired stress factor information of the target measurement area.

[0007] Optionally, a fiber emitting direction adjustment mechanism is provided at the light output end of the input light fiber, and the fiber emitting direction adjustment mechanism is used to adjust the output direction of the input light fiber so that the first light beam can be incident on the target measurement area.

[0008] Optionally, a fiber height adjustment mechanism is provided on the input optical fiber, and the fiber height adjustment mechanism is used to adjust the vertical height of the input optical fiber so that the height of the outlet end of the input optical fiber matches the height of the wafer to be measured.

[0009] Optionally, the stress monitoring system provided by the present invention further includes a light source controller communicatively connected to the light emitter, wherein the light source controller is used to control the wavelength of the first light beam provided by the light emitter to adjust the penetration depth of the first light beam in the target measurement area.

[0010] Optionally, the stress monitoring system provided by the present invention also includes an imaging lens and a second light-emitting optical fiber; the light transmitter is also used to provide a second light beam; the light-input optical fiber is also used to incident the second light beam onto the wafer to be tested, so that the second light beam is reflected on the wafer to be tested; the imaging lens is used to collect the reflected light formed on the wafer to be tested, so as to gather the reflected light into an imaging light signal; the second light-emitting optical fiber is used to transmit the imaging light signal to the photodetector; the photodetector is also used to convert the imaging light signal into a corresponding imaging electrical signal and transmit it to the processor; the processor is also used to generate a local surface morphology image of the wafer to be tested based on the imaging electrical signal, and locate the target measurement area based on the local surface morphology image.

[0011] To achieve the above object, the present invention further provides a stress monitoring method, which comprises the following steps:

[0012] Providing a first light beam using a light transmitter capable of providing light beams of different wavelengths;

[0013] Using a light input optical fiber whose output direction and vertical height are adjustable to inject the first light beam into a target measurement area of ​​the wafer to be measured, so that the first light beam is scattered in the target measurement area;

[0014] Using a first light-emitting optical fiber to collect scattered light formed in the target measurement area;

[0015] extracting a Raman scattered light signal from the scattered light;

[0016] Converting the Raman scattered light signal into a corresponding Raman scattered electrical signal;

[0017] The stress information of the target measurement area is obtained according to the Raman scattered electrical signal.

[0018] Optionally, acquiring stress information of the target measurement area according to the Raman scattered electrical signal includes:

[0019] Acquire first Raman shift information corresponding to the target measurement area according to the Raman scattered electrical signal;

[0020] Acquire relative Raman shift information corresponding to the target measurement area according to the first Raman shift information and pre-acquired second Raman shift information corresponding to the target measurement area at an initial moment;

[0021] Relative stress information of the target measurement area is obtained according to the relative Raman shift information corresponding to the target measurement area and the pre-acquired stress factor information of the target measurement area.

[0022] Optionally, the stress monitoring method provided by the present invention further includes:

[0023] Before providing the first light beam, the target measurement area is positioned.

[0024] Optionally, positioning the target measurement area includes:

[0025] Acquiring position information of the target measurement area relative to the center point of the wafer to be measured;

[0026] Acquiring target emission direction information of the incident light optical fiber according to the position information of the target measurement area relative to the center point of the wafer to be measured, and adjusting the emission direction of the incident light optical fiber according to the target emission direction information of the incident light optical fiber;

[0027] The light transmitter is used to provide a second light beam, and the second light beam provided by the light transmitter is incident on the wafer to be tested through a light input optical fiber, so that the second light beam is reflected on the wafer to be tested;

[0028] Collecting reflected light formed on the wafer to be tested, so as to gather the reflected light into an imaging light signal and transmit the imaging light signal through a second light-emitting optical fiber;

[0029] Converting the imaging optical signal into a corresponding imaging electrical signal;

[0030] Generating a local surface topography image of the wafer to be tested according to the imaging electrical signal;

[0031] The target measurement area is positioned according to the local surface topography image.

[0032] Optionally, positioning the target measurement area according to the local surface topography image includes:

[0033] Comparing the local surface topography image with a standard image corresponding to the target measurement area;

[0034] If the local surface topography image matches the standard image;

[0035] then determining that the area corresponding to the local surface topography image is the target measurement area;

[0036] If the local surface topography image does not match the standard image, the emission direction of the incident light optical fiber is readjusted.

[0037] Optionally, acquiring target emission direction information of the incident light optical fiber according to position information of the target measurement area relative to the center point of the wafer to be measured includes:

[0038] Determine a first rotation angle of the emission direction of the incident light fiber along the plane where the wafer to be measured is located according to the position information of the target measurement area relative to the center point of the wafer to be measured and the horizontal distance between the incident light fiber and the center point of the wafer to be measured;

[0039] Determine a second rotation angle of the light-emitting direction of the light-emitting fiber along a plane perpendicular to the plane where the wafer to be measured is located, according to the position information of the target measurement area relative to the center point of the wafer to be measured, the horizontal distance between the light-input fiber and the center point of the wafer to be measured, and the vertical height of the light-emitting end of the light-input fiber relative to the wafer to be measured;

[0040] According to the first rotation angle and the second rotation angle, target emission direction information of the input light optical fiber is acquired.

[0041] Optionally, the stress monitoring method provided by the present invention further includes:

[0042] The wavelength of the first light beam is adjusted to adjust the penetration depth of the first light beam in the target measurement area.

[0043] To achieve the above-mentioned purpose, the present invention also provides a furnace tube device, which includes a furnace tube and the stress monitoring system described in any one of the above items, the furnace tube includes an outer tube, an inner tube and a crystal boat, the inner tube is arranged in the outer tube, the crystal boat is arranged in the inner tube, the crystal boat is used to carry wafers, the input light fiber and the first light output fiber are both arranged between the outer tube and the inner tube, and the light emitter, the Raman probe, the photodetector and the processor are all arranged on the outside of the furnace tube.

[0044] Compared with the prior art, the stress monitoring system, stress monitoring method and furnace tube equipment provided by the present invention have the following beneficial effects:

[0045] The stress monitoring system provided by the present invention can realize non-destructive monitoring of the residual stress of the wafer under high temperature state by measuring stress based on the principle of Raman scattering, and adopting the input light fiber and the first output light fiber that can withstand high temperature for light transmission, so as to help to quickly lock the key steps of process optimization. At the same time, since the output direction of the input light fiber is adjustable, the output direction of the input light fiber (that is, the incident direction of the first light beam) can be adjusted to make the first light beam incident on any target measurement area of ​​the wafer to be measured, so as to realize the monitoring of local stress in different areas of the wafer. In addition, since the vertical height of the input light fiber is adjustable, the height of the outlet end of the input light fiber can be matched with the height of the wafer to be measured by adjusting the vertical height of the input light fiber, so as to realize the stress monitoring of different wafers on the wafer boat. In addition, since the wavelength of the first light beam provided by the optical transmitter is adjustable, the penetration depth of the first light beam provided by the optical transmitter can be adjusted to realize the real-time monitoring of the residual stress at different depths of the wafer.

[0046] Since the stress monitoring method and the furnace tube equipment provided by the present invention belong to the same inventive concept as the stress monitoring system provided by the present invention, the stress monitoring method and the furnace tube equipment provided by the present invention have at least all the beneficial effects of the stress monitoring system provided by the present invention. For details, please refer to the relevant content above regarding the beneficial effects of the stress monitoring system provided by the present invention. Therefore, the beneficial effects of the stress monitoring method and the furnace tube equipment provided by the present invention will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A stress monitoring principle diagram of a stress monitoring system provided by one embodiment of the present invention;

[0048] Figure 2 Schematic diagram of stress measurement for Raman scattering;

[0049] Figure 3 An imaging principle diagram of a stress monitoring system provided by one embodiment of the present invention;

[0050] Figure 4 A flow chart of a stress monitoring method provided by one embodiment of the present invention;

[0051] Figure 5 A schematic diagram of a target measurement area for positioning according to an embodiment of the present invention.

[0052] The reference numerals are described as follows:

[0053] Light transmitter-110; first light beam-111; second light beam-112; input light fiber-120; optical fiber output direction adjustment mechanism-121; optical fiber height adjustment mechanism-122; first light output fiber-130; Raman probe-140; photodetector-150; processor-160; light source controller-170; imaging lens-180; second light output fiber-190;

[0054] Wafer to be tested - 200; Target measurement area - 210;

[0055] Furnace tube-300; outer tube-310; inner tube-320; crystal boat-330. DETAILED DESCRIPTION

[0056] The stress monitoring system, stress monitoring method and furnace tube equipment proposed in the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Any modification of the structure, change of the proportional relationship or adjustment of the size, under the same or similar conditions as the effects that can be produced by the present invention and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present invention. The specific design features of the present invention disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific environment to be applied and used. And, in the embodiments described below, sometimes the same figure mark is used in common between different drawings to represent the same part or a part with the same function, and its repeated description is omitted. In this specification, similar numbers and letters are used to represent similar items, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings. Additionally, if the method described herein includes a series of steps, the order in which the steps are presented herein is not necessarily the only order in which the steps may be performed, and some of the steps described may be omitted and / or some other steps not described herein may be added to the method.

[0057] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0058] The core idea of ​​the present invention is to provide a stress monitoring system, a stress monitoring method and a furnace tube device, which can not only realize non-destructive monitoring of the residual stress of the wafer under high temperature conditions, but also realize real-time monitoring of the residual stress at different depths of the wafer.

[0059] To realize the above idea, the present invention provides a stress monitoring system, please refer to Figure 1 , which is a stress monitoring principle diagram of a stress monitoring system provided by an embodiment of the present invention. Figure 1 As shown, the stress monitoring system provided by the present invention includes an optical transmitter 110, an input optical fiber 120, a first output optical fiber 130, a Raman probe 140, a photodetector 150 and a processor 160, wherein the output direction of the input optical fiber 120 and the vertical height of the input optical fiber 120 are adjustable; the optical transmitter 110 is used to provide a first light beam 111, and the wavelength of the first light beam 111 provided by the optical transmitter 110 is adjustable; the input optical fiber 120 is used to irradiate the first light beam 111 into the target measurement area 210 (see Figure 5 ), so that the first light beam 111 is scattered in the target measurement area 210; the first light-emitting optical fiber 130 is used to collect the scattered light formed in the target measurement area 210, and transmit it to the Raman probe 140; the Raman probe 140 is used to extract the Raman scattered light signal from the scattered light, and transmit it to the photodetector 150; the photodetector 150 is used to convert the Raman scattered light signal into a corresponding Raman scattered electrical signal; the processor 160 is used to obtain the stress information of the target measurement area 210 according to the Raman scattered electrical signal.

[0060] It can be seen that the stress monitoring system provided by the present invention can realize non-destructive monitoring of the residual stress of the wafer under high temperature state by using the principle of stress measurement based on Raman scattering and adopting the high temperature resistant input light fiber 120 and the first output light fiber 130 for light transmission, so as to help to quickly lock the key steps of process optimization. At the same time, since the output direction of the input light fiber 120 is adjustable, the output direction of the input light fiber 120 can be adjusted to make the first light beam 111 incident on any target measurement area 210 of the wafer 200 to be tested, thereby realizing the monitoring of local stress in different areas of the wafer. In addition, since the vertical height of the input light fiber 120 is adjustable, the vertical height of the input light fiber 120 can be adjusted so that the height of the outlet end of the input light fiber 120 matches the height of the wafer 200 to be tested (the outlet end of the input light fiber 120 should be higher than the wafer 200 to be tested), thereby realizing the stress monitoring of different wafers on the wafer boat 330. In addition, since the wavelength of the first light beam 111 provided by the light emitter 110 is adjustable, the penetration depth of the first light beam 111 can be adjusted by adjusting the wavelength of the first light beam 111 provided by the light emitter 110, thereby achieving real-time monitoring of residual stress at different depths of the wafer.

[0061] Specifically, the principle of Raman scattering to measure stress is: when light shines on a material, part of the light will be scattered, and the frequency of part of the scattered light will change. This change in frequency is called Raman shift, also known as the movement of the Raman peak frequency, which reflects the vibration mode and structural information inside the material. Taking a thin film as an example, when there is residual stress of tension or compression in the film, the bond length of the atoms will be elongated or shortened accordingly, causing the stress constant of the film to decrease or increase, and thus the vibration frequency of the atoms will decrease or increase, causing the peak of the Raman spectrum to move to a low frequency or high frequency. Please refer to Figure 2 , which is a schematic diagram of the principle of Raman scattering stress measurement. Figure 2 As shown, when the material is subjected to compressive stress, the peak of the Raman spectrum will move to high frequency; when the material is subjected to tensile stress, the peak of the Raman spectrum will move to low frequency. And the movement of the Raman peak frequency (hereinafter referred to as the Raman peak frequency shift) has a linear relationship with the magnitude of the residual stress inside the film. Based on this, the present invention can measure the stress information of the target measurement area 210 by collecting the Raman scattering signal of the target measurement area 210 of the wafer 200 to be measured.

[0062] In some exemplary embodiments, the input optical fiber 120 and the first output optical fiber 130 are both quartz optical fibers. Since quartz optical fibers have the characteristic of high temperature resistance, by using quartz optical fibers as the input optical fiber 120 and the first output optical fiber 130 in the present invention, it can be effectively ensured that the input optical fiber 120 and the first output optical fiber 130 can conduct light in a high temperature environment, thereby effectively ensuring that the stress monitoring system provided by the present invention can realize residual stress monitoring of wafers under high temperature conditions (the maximum temperature can reach 1300°C).

[0063] In some exemplary embodiments, the light emitter 110 is a laser. Thus, the present invention uses a laser as the light emitter 110 that provides the first light beam 111, so that the first light beam 111 (laser) provided by the light emitter 110 can be ensured to have the advantages of good monochromaticity, high coherence, and strong directionality. Specifically, the laser can be any one of a pulse laser, a solid laser, a gas laser, a semiconductor laser, a dye laser, or a fiber laser.

[0064] Please continue to refer to Figure 1 ,like Figure 1 As shown, in some exemplary embodiments, the stress monitoring system provided by the present invention further includes a light source controller 170 that is communicatively connected to the light emitter 110, and the light source controller 170 is used to control the wavelength of the first light beam 111 provided by the light emitter 110 to adjust the penetration depth of the first light beam 111. Therefore, by setting the light source controller 170, it is possible to achieve precise control of the wavelength of the first light beam 111 provided by the light emitter 110, so as to achieve monitoring of stress at different depths of the wafer 200 to be tested.

[0065] Specifically, please refer to Table 1, which shows the absorption coefficient (α) and penetration depth (d) corresponding to light of different wavelengths (λ) in silicon crystal. p ).

[0066] Table 1 Absorption coefficient and penetration depth of light of different wavelengths in silicon crystal

[0067] λ(nm) λ(eV) <![CDATA[α(10 -3 cm -1 )]]> <![CDATA[d p (nm)]]> 514.5 2.410 14.96 770 488.0 2.541 20.18 570 457.9 2.708 36.43 320

[0068] According to the above table, the wavelength and penetration depth mapping relationship corresponding to the silicon crystal can be obtained. Therefore, the wavelength of the first light beam 111 incident on the target measurement area 210 can be determined according to the target detection depth information of the target measurement area 210 and the wavelength and penetration depth mapping relationship corresponding to the wafer 200 to be measured.

[0069] In some exemplary embodiments, the processor 160 is configured to:

[0070] Acquire first Raman shift information corresponding to the target measurement area 210 according to the Raman scattered electrical signal;

[0071] Acquire relative Raman shift information corresponding to the target measurement area 210 according to the first Raman shift information and pre-acquired second Raman shift information corresponding to the target measurement area 210 at an initial moment;

[0072] Relative stress information of the target measurement area 210 is acquired according to the relative Raman shift information corresponding to the target measurement area 210 and the pre-acquired stress factor information of the target measurement area 210 .

[0073] Thus, by pre-acquiring the second Raman shift w0 corresponding to the target measurement area 210 at the initial time (for example, the initial time t0 before the start of annealing), the target measurement area 210 at the current time t i The first Raman shift w of (i=1, 2, ..., n) i (i=1, 2, ..., n) and the second Raman shift w0, calculate the target measurement area 210 at the current time t i Relative Raman shift Δw relative to the initial time t0 i =w i -w0, and then the relative Raman shift Δw can be calculated i And the stress factor k of the target measurement area 210 obtained in advance, that is, the relative stress σ of the target measurement area 210 at this moment relative to the initial moment can be calculated i (i=1, 2,…, n).

[0074] Specifically, the relative stress σ of the target measurement area 210 can be calculated in real time according to the following formula: i :

[0075] σ i = kΔw i

[0076] Wherein, k is the stress factor of the wafer 200 to be tested.

[0077] Please continue to refer to Table 2, which shows the relationship between stress and time during annealing.

[0078] Table 2 Relationship between stress and time

[0079] time <![CDATA[Raman shift w i > <![CDATA[Relative Raman shift Δw i > Relative stress <![CDATA[t0]]> <![CDATA[w0]]> 0 0 <![CDATA[t1]]> <![CDATA[w1]]> <![CDATA[w1-w0]]> <![CDATA[k(w1-w0)]]> … … … … <![CDATA[t n ]]> <![CDATA[w n ]]> <![CDATA[w n -w0]]> <![CDATA[k(w n -w0)]]>

[0080] It should be noted that the specific value of the stress factor is related to the material of the target measurement area 210. For example, when the material of the target measurement area 210 is polycrystalline silicon, the stress factor k=-0.063 (cm·GPA), and when the material of the target measurement area 210 is single crystal silicon, the stress factor k=-464.64 (cm·GPA).

[0081] In some exemplary embodiments, the light output end of the input optical fiber 120 is provided with an optical fiber output direction adjustment mechanism 121, and the optical fiber output direction adjustment mechanism 121 is used to adjust the output direction of the input optical fiber 120 so that the first light beam 111 can be incident on the target measurement area 210. Therefore, by providing the optical fiber output direction adjustment mechanism 121 capable of adjusting the output direction of the input optical fiber 120 (the direction incident on the wafer 200 to be measured) at the light output end of the input optical fiber 120, it can be ensured that the first light beam 111 can accurately be incident on any target measurement area 210 on the wafer 200 to be measured, thereby effectively ensuring the accuracy of the stress monitoring result.

[0082] It should be noted that the present invention does not limit the specific structure of the optical fiber emission direction adjustment mechanism 121. For example, the optical fiber emission direction adjustment mechanism 121 may include an optical output port (not shown in the figure) and a first driving device (not shown in the figure) for driving the optical output port to rotate relative to the light input optical fiber 120, and the first driving device may be a servo motor.

[0083] In some exemplary embodiments, the input optical fiber 120 is provided with an optical fiber height adjustment mechanism 122, and the optical fiber height adjustment mechanism 122 is used to adjust the vertical height of the input optical fiber 120 so that the height of the outlet end of the input optical fiber 120 matches the height of the wafer 200 to be tested. Therefore, by providing the optical fiber height adjustment mechanism 122 on the input optical fiber 120, the height of the outlet end of the input optical fiber 120 can be adjusted according to the height of the wafer 200 to be tested, so as to ensure that the first light beam 111 can be smoothly incident on the wafer 200 to be tested via the input optical fiber 120, so as to realize stress monitoring of different wafers on the wafer boat 330.

[0084] It should be noted that the present invention does not limit the specific structure of the optical fiber height adjustment mechanism 122. For example, the optical fiber height adjustment mechanism 122 includes a telescopic optical fiber segment (not shown in the figure) and a second driving device (not shown in the figure) for controlling the telescopic optical fiber segment to be telescopic, and the second driving device can be a servo motor.

[0085] Please continue to refer to Figure 3, which is an imaging principle diagram of a stress monitoring system provided by an embodiment of the present invention. Figure 3 As shown, the stress monitoring system provided by the present invention also includes an imaging lens 180 and a second light-emitting optical fiber 190; the light transmitter 110 is also used to provide a second light beam 112; the light-input optical fiber 120 is also used to incident the second light beam 112 onto the wafer to be tested 200, so that the second light beam 112 is reflected on the wafer to be tested 200; the imaging lens 180 is used to collect the reflected light formed on the wafer to be tested 200, so as to gather the reflected light into an imaging light signal; the second light-emitting optical fiber 190 is used to transmit the imaging light signal to the photodetector 150; the photodetector 150 is also used to convert the imaging light signal into a corresponding imaging electrical signal, and transmit it to the processor 160; the processor 160 is also used to generate a local surface morphology image of the wafer to be tested 200 according to the imaging electrical signal, and locate the target measurement area 210 according to the local surface morphology image. Therefore, by setting the imaging lens 180 and the second light-emitting optical fiber 190 to collect the local surface morphology image of the wafer 200 to be tested, the target measurement area 210 can be more accurately positioned based on the local surface morphology image, thereby effectively ensuring the accuracy of the stress monitoring result.

[0086] Specifically, the second light beam 112 may be white light, and the imaging lens 180 and the second light-emitting optical fiber 190 are both made of high-temperature resistant materials, for example, the second light-emitting optical fiber 190 may be a quartz optical fiber. It should be noted that, as those skilled in the art can understand, the present invention does not limit the specific structure of the imaging lens 180, and the specific structure and working principle of the imaging lens 180 may be adaptively understood by referring to the relevant contents in the field of optical imaging known to those skilled in the art, and will not be further described here.

[0087] Further, the processor 160 is used to compare the local surface topography image with the standard image corresponding to the target measurement area 210, and if the local surface topography image matches the standard image, the area corresponding to the local surface topography image is determined to be the target measurement area 210. Thus, by determining the area corresponding to the local surface topography image that matches the standard image corresponding to the target measurement area 210 as the target measurement area 210, the accuracy of the positioning of the target measurement area 210 can be effectively guaranteed, thereby effectively ensuring the accuracy of the stress monitoring result.

[0088] It should be noted that if the local surface morphology image does not match the standard image, the incident direction of the second light beam 112 is readjusted to recapture the local surface morphology image of the wafer 200 to be tested until the newly captured local surface morphology image matches the standard image.

[0089] To achieve the above object, the present invention also provides a stress monitoring method, which is applied to the stress monitoring system provided by the present invention. Figure 4 , which is a flow chart of a stress monitoring method provided by one embodiment of the present invention. Figure 4 As shown, the stress monitoring method provided by the present invention comprises the following steps:

[0090] Step S100: using a light emitter 110 capable of providing light beams of different wavelengths to provide a first light beam 111 .

[0091] Step S200 : using the light input optical fiber 120 with adjustable emission direction and vertical height to inject the first light beam 111 into the target measurement area 210 of the wafer 200 to be measured, so that the first light beam 111 is scattered in the target measurement area 210 .

[0092] Step S300 : using the first light-emitting optical fiber 130 to collect scattered light generated in the target measurement area 210 .

[0093] Step S400: extracting a Raman scattered light signal from the scattered light.

[0094] Step S500: converting the Raman scattered light signal into a corresponding Raman scattered electrical signal.

[0095] Step S600: Obtain stress information of the target measurement area 210 according to the Raman scattered electrical signal.

[0096] Therefore, the stress monitoring method provided by the present invention can realize non-destructive monitoring of the residual stress of the wafer under high temperature state by using the principle of stress measurement based on Raman scattering and adopting the high temperature resistant input light fiber 120 and the first output light fiber 130 for light transmission, so as to help to quickly lock the key steps of process optimization. At the same time, since the output direction of the input light fiber 120 is adjustable, the output direction of the input light fiber 120 can be adjusted to make the first light beam 111 incident on any target measurement area 210 of the wafer 200 to be tested, thereby realizing the monitoring of local stress in different areas of the wafer. In addition, since the vertical height of the input light fiber 120 is adjustable, the height of the outlet end of the input light fiber 120 can be matched with the height of the wafer 200 to be tested by adjusting the vertical height of the input light fiber 120 (the outlet end of the input light fiber 120 should be higher than the wafer 200 to be tested), thereby realizing the stress monitoring of different wafers on the wafer boat 330. In addition, since the wavelength of the first light beam 111 provided by the light emitter 110 is adjustable, the penetration depth of the first light beam 111 can be adjusted by adjusting the wavelength of the first light beam 111 provided by the light emitter 110, thereby achieving real-time monitoring of residual stress at different depths of the wafer.

[0097] In some exemplary embodiments, obtaining stress information of the target measurement area 210 according to the Raman scattered electrical signal includes:

[0098] Acquire first Raman shift information corresponding to the target measurement area 210 according to the Raman scattered electrical signal;

[0099] Acquire relative Raman shift information corresponding to the target measurement area 210 according to the first Raman shift information and pre-acquired second Raman shift information corresponding to the target measurement area 210 at an initial moment;

[0100] Relative stress information of the target measurement area 210 is acquired according to the relative Raman shift information corresponding to the target measurement area 210 and the pre-acquired stress factor information of the target measurement area 210 .

[0101] In some exemplary embodiments, before providing the first light beam 111, the stress monitoring method provided by the present invention includes:

[0102] The target measurement area 210 is positioned.

[0103] Therefore, by positioning the target measurement area 210 before providing the first light beam 111 , the accuracy of the stress monitoring result can be effectively guaranteed.

[0104] In some exemplary embodiments, positioning the target measurement area 210 includes:

[0105] Acquire the position information of the target measurement area 210 relative to the center point A of the wafer to be measured 200;

[0106] According to the position information of the target measurement area 210 relative to the center point A of the wafer to be measured 200, the target emission direction information of the incident light optical fiber 120 is obtained, and the emission direction of the incident light optical fiber 120 is adjusted according to the target emission direction information of the incident light optical fiber 120;

[0107] The light emitter 110 is used to provide a second light beam 112, and the second light beam 112 provided by the light emitter 110 is incident on the wafer 200 to be tested through the light input fiber 120, so that the second light beam 112 is reflected on the wafer 200 to be tested;

[0108] Collecting the reflected light formed on the wafer 200 to be tested, so as to gather the reflected light into an imaging light signal and transmit the imaging light signal through the second light-emitting optical fiber 190;

[0109] Converting the imaging optical signal into a corresponding imaging electrical signal;

[0110] Generating a local surface topography image of the wafer 200 to be tested according to the imaging electrical signal;

[0111] The target measurement area 210 is positioned according to the local surface topography image.

[0112] In some exemplary embodiments, the step of acquiring target emission direction information of the input optical fiber 120 according to the position information of the target measurement area 210 relative to the center point A of the wafer 200 to be measured includes:

[0113] Determine a first rotation angle of the emission direction of the incident light fiber 120 along the plane where the wafer 200 to be measured is located according to the position information of the target measurement area 210 relative to the center point A of the wafer to be measured 200 and the horizontal distance between the incident light fiber 120 and the center point A of the wafer to be measured 200;

[0114] According to the position information of the target measurement area 210 relative to the center point A of the wafer to be measured 200, the horizontal distance between the input light fiber 120 and the center point A of the wafer to be measured 200, and the vertical height of the light output end of the input light fiber 120 relative to the wafer to be measured 200, determine the second rotation angle of the output direction of the input light fiber 120 along the plane perpendicular to the plane where the wafer to be measured 200 is located;

[0115] According to the first rotation angle and the second rotation angle, target emission direction information of the input light optical fiber 120 is acquired.

[0116] Specifically, the position coordinates of the target measurement area 210 relative to the center point A of the wafer 200 to be tested can be determined based on the defect map corresponding to the wafer 200 to be tested that is obtained in advance. Figure 5 , which is a schematic diagram of positioning the target measurement area 210 provided by one embodiment of the present invention. Figure 5 As shown in the figure, (x0, y0) represents the position coordinates of the target measurement area 210 relative to the center point A of the wafer 200 to be measured, the vertical height of the light-emitting end of the input optical fiber 120 (i.e., the light source in the figure) relative to the wafer 200 to be measured is H, and the horizontal distance between the input optical fiber 120 and the center point A of the wafer 200 to be measured is D. Then, the first rotation angle β of the emission direction (optical axis) of the input optical fiber 120 along the plane where the wafer 200 to be measured is located can be calculated according to the following formula:

[0117]

[0118] The second rotation angle α of the emission direction of the incident light optical fiber 120 along the plane where the wafer to be tested 200 is located is calculated according to the following formula:

[0119]

[0120] In some exemplary embodiments, positioning the target measurement area 210 according to the local surface topography image includes:

[0121] Comparing the local surface topography image with a standard image corresponding to the target measurement area 210;

[0122] If the local surface topography image matches the standard image;

[0123] Then, the area corresponding to the local surface topography image is determined to be the target measurement area 210;

[0124] If the local surface topography image does not match the standard image, the emission direction of the incident light optical fiber 120 is readjusted.

[0125] Specifically, if the local surface morphology image matches the standard image, it indicates that the first light beam 111 can be smoothly incident on the target measurement area 210 along the emission direction of the input optical fiber 120, which means that the area corresponding to the local surface morphology image is the target measurement area 210, thereby achieving accurate positioning of the target measurement area 210.

[0126] It should be noted that, as can be understood by those skilled in the art, in the process of readjusting the emission direction of the input light fiber 120, the rotation angle of the emission direction (optical axis) of the input light fiber 120 along the plane where the wafer 200 to be tested is located and / or the rotation angle of the emission direction of the input light fiber 120 along the plane where the wafer 200 to be tested is located can be fine-tuned, and the local surface morphology image of the wafer 200 to be tested can be recaptured until the newly captured local surface morphology image matches the standard image. It should also be noted that, as can be understood by those skilled in the art, due to the influence of factors such as process deviation and wafer placement deviation, the actual position of the target measurement area 210 will deviate, thereby causing the target emission direction of the input light fiber 120 determined based on the position information of the target measurement area 210 relative to the center point A of the wafer 200 to be measured to deviate, thereby causing the first light beam 111 emitted along the target emission direction to fail to accurately enter the target measurement area 210. Therefore, by collecting a local surface morphology image of the corresponding area under the target emission direction and matching it with the standard image corresponding to the target measurement area 210, accurate positioning of the target measurement area 210 can be achieved.

[0127] In some exemplary embodiments, the stress monitoring method provided by the present invention further includes:

[0128] The wavelength of the first light beam 111 is adjusted to adjust the penetration depth of the first light beam 111 in the target measurement area 210 .

[0129] Based on the same inventive concept, the present invention also provides a furnace tube device, please refer to Figure 1 and Figure 3 ,like Figure 1 and Figure 3 As shown, the furnace tube device provided by the present invention comprises an outer tube 310, an inner tube 320 and a wafer boat 330, wherein the inner tube 320 is arranged in the outer tube 310, the wafer boat 330 is arranged in the inner tube 320, the wafer boat 330 is used to carry wafers, the light input fiber 120 and the first light output fiber 130 are both arranged between the outer tube 310 and the inner tube 320, and the light transmitter 110, the Raman probe 140, the photodetector 150 and the processor 160 are all arranged on the outside of the furnace tube 300. Since the furnace tube device provided by the present invention and the stress monitoring system provided by the present invention belong to the same inventive concept, the furnace tube device provided by the present invention at least has all the beneficial effects of the stress monitoring system provided by the present invention, and the relevant contents about the beneficial effects of the stress monitoring system provided by the present invention can be referred to above, so the beneficial effects of the furnace tube device provided by the present invention will not be described one by one here.

[0130] Please continue to refer to Figure 3 ,like Figure 3 As shown, the imaging lens 180 and the second light-emitting optical fiber 190 are also disposed between the outer tube 310 and the inner tube 320 .

[0131] It should be noted that, as those skilled in the art can understand, since the inner tube 320 in the furnace tube 300 and the crystal boat 330 are generally made of quartz material, they are light-transmissive.

[0132] In summary, compared with the prior art, the stress monitoring system, stress monitoring method and furnace tube equipment provided by the present invention have the following beneficial effects:

[0133] The present invention can realize non-destructive monitoring of residual stress of wafers under high temperature state by using the principle of stress measurement based on Raman scattering and using the input optical fiber 120 and the first output optical fiber 130 for light transmission, so as to help to quickly lock the key steps of process optimization. At the same time, since the output direction of the input optical fiber 120 is adjustable, the output direction of the input optical fiber 120 (that is, the incident direction of the first light beam 111) can be adjusted to make the first light beam 111 incident on any target measurement area 210 of the wafer 200 to be measured, thereby realizing monitoring of local stress in different areas of the wafer. In addition, since the vertical height of the input optical fiber 120 is adjustable, the height of the outlet end of the input optical fiber 120 can be matched with the height of the wafer 200 to be measured by adjusting the vertical height of the input optical fiber 120, thereby realizing stress monitoring of different wafers on the wafer boat 330. In addition, since the wavelength of the first light beam 111 provided by the light emitter 110 is adjustable, the penetration depth of the first light beam 111 can be adjusted by adjusting the wavelength of the first light beam 111 provided by the light emitter 110, thereby achieving real-time monitoring of residual stress at different depths of the wafer.

[0134] It should be noted that the above description is only a description of the preferred embodiment of the present invention, and is not any limitation on the scope of the present invention. Any changes and modifications made by a person skilled in the art in the field of the present invention based on the above disclosure are within the scope of protection of the present invention. Obviously, a person skilled in the art can make various changes and modifications to the invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations fall within the scope of the present invention and its equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A stress monitoring system, characterized in that: It includes an optical transmitter, an input optical fiber, a first output optical fiber, a Raman probe, a photoelectric detector and a processor, and the output direction of the input optical fiber and the vertical height of the input optical fiber are adjustable; The light emitter is used to provide a first light beam, and the wavelength of the first light beam provided by the light emitter is adjustable; The light input optical fiber is used to inject the first light beam into the target measurement area of ​​the wafer to be measured, so that the first light beam is scattered in the target measurement area; The first light-emitting optical fiber is used to collect scattered light formed in the target measurement area and transmit it to the Raman probe; The Raman probe is used to extract a Raman scattered light signal from the scattered light and transmit it to the photoelectric detector; The photodetector is used to convert the Raman scattered light signal into a corresponding Raman scattered electrical signal and transmit it to the processor; The processor is used for acquiring stress information of the target measurement area according to the Raman scattered electrical signal.

2. The stress monitoring system according to claim 1, characterized in that: The processor is used to: Acquire first Raman shift information corresponding to the target measurement area according to the Raman scattered electrical signal; Acquire relative Raman shift information corresponding to the target measurement area according to the first Raman shift information and pre-acquired second Raman shift information corresponding to the target measurement area at an initial moment; Relative stress information of the target measurement area is obtained according to the relative Raman shift information corresponding to the target measurement area and the pre-acquired stress factor information of the target measurement area.

3. The stress monitoring system according to claim 1, characterized in that: The light output end of the input light optical fiber is provided with a fiber output direction adjustment mechanism, and the fiber output direction adjustment mechanism is used to adjust the output direction of the input light optical fiber so that the first light beam can be incident on the target measurement area.

4. The stress monitoring system according to claim 1, characterized in that: The light input optical fiber is provided with a fiber height adjustment mechanism, and the fiber height adjustment mechanism is used to adjust the vertical height of the light input optical fiber so that the height of the outlet end of the light input optical fiber matches the height of the wafer to be measured.

5. The stress monitoring system according to claim 1, characterized in that: Also included is a light source controller that is communicatively connected to the light emitter, and the light source controller is used to control the wavelength of the first light beam provided by the light emitter to adjust the penetration depth of the first light beam in the target measurement area.

6. The stress monitoring system according to claim 1, characterized in that: Also includes an imaging lens and a second light-emitting optical fiber; The light emitter is also used to provide a second light beam; The light input optical fiber is also used to inject the second light beam onto the wafer to be tested, so that the second light beam is reflected on the wafer to be tested; The imaging lens is used to collect the reflected light formed on the wafer to be tested, so as to gather the reflected light into an imaging light signal; The second light-emitting optical fiber is used to transmit the imaging light signal to the photodetector; The photodetector is also used to convert the imaging light signal into a corresponding imaging electrical signal and transmit it to the processor; The processor is further configured to generate a local surface topography image of the wafer to be measured according to the imaging electrical signal, and locate the target measurement area according to the local surface topography image.

7. A stress monitoring method, characterized in that: include: Providing a first light beam using a light transmitter capable of providing light beams of different wavelengths; Using a light input optical fiber whose output direction and vertical height are adjustable to inject the first light beam into a target measurement area of ​​the wafer to be measured, so that the first light beam is scattered in the target measurement area; Using a first light-emitting optical fiber to collect scattered light generated in the target measurement area; extracting a Raman scattered light signal from the scattered light; Converting the Raman scattered light signal into a corresponding Raman scattered electrical signal; The stress information of the target measurement area is obtained according to the Raman scattered electrical signal.

8. The stress monitoring method according to claim 7, characterized in that: The step of acquiring stress information of the target measurement area according to the Raman scattered electrical signal comprises: Acquire first Raman shift information corresponding to the target measurement area according to the Raman scattered electrical signal; Acquire relative Raman shift information corresponding to the target measurement area according to the first Raman shift information and pre-acquired second Raman shift information corresponding to the target measurement area at an initial moment; Relative stress information of the target measurement area is obtained according to the relative Raman shift information corresponding to the target measurement area and the pre-acquired stress factor information of the target measurement area.

9. The stress monitoring method according to claim 7, characterized in that: Prior to providing the first light beam, the method comprises: The target measurement area is positioned.

10. The stress monitoring method according to claim 9, characterized in that: The positioning of the target measurement area includes: Acquiring position information of the target measurement area relative to the center point of the wafer to be measured; Acquiring target emission direction information of the incident light optical fiber according to the position information of the target measurement area relative to the center point of the wafer to be measured, and adjusting the emission direction of the incident light optical fiber according to the target emission direction information of the incident light optical fiber; The light transmitter is used to provide a second light beam, and the second light beam provided by the light transmitter is incident on the wafer to be tested through a light input optical fiber, so that the second light beam is reflected on the wafer to be tested; Collecting reflected light formed on the wafer to be tested, so as to gather the reflected light into an imaging light signal and transmit the imaging light signal through a second light-emitting optical fiber; Converting the imaging optical signal into a corresponding imaging electrical signal; Generating a local surface topography image of the wafer to be tested according to the imaging electrical signal; The target measurement area is positioned according to the local surface topography image.

11. The stress monitoring method according to claim 10, characterized in that: The positioning of the target measurement area according to the local surface topography image includes: Comparing the local surface topography image with a standard image corresponding to the target measurement area; If the local surface topography image matches the standard image; then determining that the area corresponding to the local surface topography image is the target measurement area; If the local surface topography image does not match the standard image, the emission direction of the incident light optical fiber is readjusted.

12. The stress monitoring method according to claim 10, characterized in that: The step of obtaining target emission direction information of the incident light optical fiber according to the position information of the target measurement area relative to the center point of the wafer to be measured comprises: Determine a first rotation angle of the emission direction of the incident light fiber along the plane where the wafer to be measured is located according to the position information of the target measurement area relative to the center point of the wafer to be measured and the horizontal distance between the incident light fiber and the center point of the wafer to be measured; Determine a second rotation angle of the light-emitting direction of the light-emitting fiber along a plane perpendicular to the plane where the wafer to be measured is located, according to the position information of the target measurement area relative to the center point of the wafer to be measured, the horizontal distance between the light-input fiber and the center point of the wafer to be measured, and the vertical height of the light-emitting end of the light-input fiber relative to the wafer to be measured; According to the first rotation angle and the second rotation angle, target emission direction information of the input light optical fiber is acquired.

13. The stress monitoring method according to claim 7, characterized in that: The method further comprises: The wavelength of the first light beam is adjusted to adjust the penetration depth of the first light beam in the target measurement area.

14. A furnace tube device, characterized in that: The invention comprises a furnace tube and the stress monitoring system according to any one of claims 1 to 6, wherein the furnace tube comprises an outer tube, an inner tube and a wafer boat, the inner tube is arranged in the outer tube, the wafer boat is arranged in the inner tube, the wafer boat is used to carry wafers, the input optical fiber and the first output optical fiber are both arranged between the outer tube and the inner tube, and the optical transmitter, the Raman probe, the photodetector and the processor are all arranged on the outside of the furnace tube.

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