Semiconductor structure and acceleration detection method thereof, optical coupling packaging combination

Abstract

A semiconductor structure and an acceleration detection method and an optical coupling packaging combination thereof, wherein the semiconductor structure comprises: an optical cavity layer, a laser signal enters from the first surface of the optical cavity layer; a resonance layer, the first surface of the resonance layer faces the second surface of the optical cavity layer, wherein the resonance layer comprises: a mass block, the mass block can vibrate in a direction perpendicular to the first surface of the resonance layer, and a first optical resonance cavity is formed between the second surface of the optical cavity layer and the surface of the mass block facing the second surface of the optical cavity layer; wherein the laser signal forms a comb-shaped spectrum in the first optical resonance cavity, and the cavity length of the first optical resonance cavity is determined by a first frequency based on the minimum wavelength of the laser bandwidth and a second frequency based on the maximum wavelength of the laser bandwidth. The present invention can more accurately determine the cavity length of the first optical resonance cavity, and effectively improve the precision of subsequent acceleration detection.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic technology, and in particular to a semiconductor structure and an acceleration detection method thereof, and an optical coupling packaging combination. Background Art

[0002] At present, the main technical methods commonly used for acceleration sensors are divided into electrical and optical types. Acceleration sensors of the electrical type include piezoelectric technology, piezoresistive technology, and capacitive technology, etc., which are active sensing technologies; acceleration sensors of the optical type include (Fiber Bragg Grating) fiber Bragg grating technology, laser dynamic ranging technology, optical flow field technology, etc., which are passive sensing technologies.

[0003] However, existing electrical acceleration sensors often have common defects. Since they are active detection, in very harsh environments, such as high electromagnetic, high current, high voltage, electrostatic dust, flammable and explosive, extreme temperature (such as less than -50℃ and higher than 120℃), their signals show poor signal-to-noise ratio and cannot even perform effective detection.

[0004] In addition, although the existing optical acceleration sensors are passive sensor chips and can be used in extremely harsh environments, the accuracy of the existing optical acceleration sensors in detecting parameters such as acceleration is often poor. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a semiconductor structure and an acceleration detection method thereof, and an optical coupling packaging combination, which can more accurately determine the cavity length of the first optical resonant cavity and effectively improve the precision of subsequent acceleration detection.

[0006] To solve the above technical problems, an embodiment of the present invention provides a semiconductor structure, comprising: an optical cavity layer, a laser signal enters from a first surface of the optical cavity layer, wherein a second surface of the optical cavity layer has a first reflective film; a resonance layer, wherein the first surface of the resonance layer faces the second surface of the optical cavity layer, wherein the resonance layer comprises: a mass block, wherein the mass block can vibrate in a direction perpendicular to the first surface of the resonance layer, and a second reflective film is provided on a surface of the mass block facing the second surface of the optical cavity layer, so that a first optical resonance cavity is formed between the second surface of the optical cavity layer and the surface of the mass block facing the second surface of the optical cavity layer; wherein the laser signal forms a comb-shaped spectrum in the first optical resonance cavity, and a cavity length of the first optical resonance cavity is determined by a first frequency based on a minimum wavelength of a laser bandwidth and a second frequency based on a maximum wavelength of the laser bandwidth.

[0007] Optionally, the cavity length of the first optical resonant cavity satisfies the following formula:

[0008] ;

[0009] in, It is used to represent the cavity length of the first optical resonant cavity, The first frequency used to represent the minimum wavelength based on the laser bandwidth, A second frequency representing the maximum wavelength based on the laser bandwidth; c represents the speed of light, λ min Minimum wavelength used to express the bandwidth of a laser, λ max Used to express the maximum wavelength of the laser bandwidth, Used to represent the refractive index coefficient of the first optical resonant cavity.

[0010] Optionally, the first surface of the optical cavity layer has a first anti-reflection film; the transmittance of the first anti-reflection film is greater than or equal to a first transmittance threshold.

[0011] Optionally, the reflectivity of the first reflective film is greater than or equal to a first reflectivity threshold R th_1 ; and / or, the second reflective film is greater than or equal to the first reflectivity threshold R th_1 .

[0012] Optionally, the reflectivity of the first surface of the optical cavity layer is selected from [R th_2 , R th_3 ], where R th_2 Used to represent the second reflectivity threshold, R th_3 is used to represent the third reflectivity threshold, and R th_2 ≤R th_3 ≤R th_1 ; Wherein, a second optical resonant cavity is formed in the optical cavity layer material between the first surface of the optical cavity layer and the second surface of the optical cavity layer.

[0013] Optionally, the material of the optical cavity layer is a silicon-based material, and the first surface of the optical cavity layer has no reflective film or anti-reflective film; or, the first surface of the optical cavity layer has a third reflective film, and the reflectivity of the third reflective film is [R th_2 , R th_3 ].

[0014] Optionally, the cavity length of the second optical resonant cavity satisfies the following formula:

[0015] ;

[0016] in, is used to represent the cavity length of the second optical resonant cavity, The first frequency used to represent the minimum wavelength based on the laser bandwidth, A second frequency representing the maximum wavelength based on the laser bandwidth; c represents the speed of light, λ min Minimum wavelength used to express the bandwidth of a laser, λ max Used to express the maximum wavelength of the laser bandwidth, is used to represent the refractive index coefficient of the second optical resonant cavity.

[0017] Optionally, the resonance layer includes: a frame; a plurality of elastic connecting components, which are symmetrically connected to the two inner sides of the frame; the mass block is suspended from the frame through the elastic connecting components and is surrounded by the frame; wherein, the mass block can vibrate in a direction perpendicular to the first surface of the resonance layer under the drive of the elastic connecting components.

[0018] Optionally, the plurality of elastic connecting components include at least two groups of elastic connecting components that are distributed in a mirror image; wherein the mirror image planes of the two groups of elastic connecting components are parallel to the plane where the frame is located.

[0019] Optionally, the elastic connecting component is curved or in the shape of a fold line, and includes one or more of the following: the elastic connecting component is an I-shaped fold line; the elastic connecting component is a T-shaped fold line; the elastic connecting component is an S-shaped fold line; the elastic connecting component is a W-shaped fold line; the elastic connecting component is an L-shaped fold line; the elastic connecting component is an X-shaped fold line; the elastic connecting component is an M-shaped fold line; the elastic connecting component is a hollow structure.

[0020] Optionally, the frame, the plurality of elastic connecting components and the mass block are an integrally formed structure formed by a semiconductor manufacturing process.

[0021] Optionally, the second surface of the resonance layer has a second anti-reflection film; wherein the transmittance of the second anti-reflection film is greater than or equal to a second transmittance threshold.

[0022] Optionally, the second surface of the optical cavity layer has a first recessed portion, and the bottom surface of the first recessed portion is a plane; wherein the first reflective film is located on the bottom surface of the recessed portion; and the projection of the mass block on the second surface of the optical cavity layer is within the bottom surface of the first recessed portion.

[0023] Optionally, the semiconductor structure also includes: a capping layer, the first surface of the capping layer faces the second surface of the resonance layer; wherein the surface roughness of the first surface of the capping layer is greater than or equal to a first surface roughness threshold; or, the first surface of the capping layer and the second surface of the capping layer are both coated with a third anti-reflection film, wherein the transmittance of the third anti-reflection film is greater than or equal to a third transmittance threshold, and the first surface of the capping layer is opposite to the second surface of the capping layer.

[0024] Optionally, the first surface of the capping layer has a second recessed portion, and the bottom surface of the second recessed portion is a plane; wherein the surface roughness of the bottom surface of the second recessed portion is greater than or equal to the first surface roughness threshold; and the projection of the mass block on the first surface of the capping layer is within the bottom surface of the second recessed portion.

[0025] Optionally, the semiconductor structure includes one or more of the following: the optical cavity layer and the resonance layer are connected by bonding; the distance between the second surface of the optical cavity layer and the first surface of the resonance layer is greater than or equal to the maximum displacement amplitude of the mass block; the resonance layer and the capping layer are connected by bonding; the optical cavity layer is formed based on a semiconductor substrate after double-sided polishing; the resonance layer is formed based on a semiconductor substrate after double-sided polishing; the capping layer is formed based on a semiconductor substrate after single-sided polishing, and the first surface of the capping layer is a polished surface.

[0026] In order to solve the above technical problems, an embodiment of the present invention provides an acceleration detection method based on the above semiconductor structure, wherein the mass block vibrates in a direction perpendicular to the first surface of the resonant layer; the method comprises: determining the displacement amplitude of the mass block at time t , wherein the mass block vibrates in a direction perpendicular to the first surface of the resonant layer, and the displacement amplitude is Used to represent the difference between the position of the mass block at time t and the position when it is in a static state; determine the acceleration of the mass block in a direction perpendicular to the first surface of the resonance layer.

[0027] Optionally, the following formula is used to determine the acceleration of the mass block in a direction perpendicular to the first surface of the resonance layer:

[0028] ;

[0029] in, For expressing the acceleration, Used to represent the spring constant of the mass, Used to indicate the mass of the mass block, Used to represent the displacement amplitude of the mass block at time t.

[0030] Optionally, the following formula is used to determine the acceleration of the mass block in a direction perpendicular to the first surface of the resonance layer:

[0031] ;

[0032] in, is used to represent the acceleration of the mass block in a direction perpendicular to the first surface of the resonant layer and at the current temperature Temp, It is used to represent the spring constant of the mass block at the current temperature Temp. Used to indicate the mass of the mass block, It is used to represent the displacement amplitude of the mass block at the current temperature Temp at time t. Used to represent FP cavity Absolute cavity length at current temperature Temp.

[0033] Optionally, determine the displacement amplitude of the mass block at time t , comprising: determining the distance between the first surface of the mass block when it is in a stationary state and the second surface of the optical cavity layer ; Use the following formula to determine the displacement amplitude of the mass block at time t :

[0034] ;

[0035] ;

[0036] in, It is used to represent the real-time cavity length of the first optical resonant cavity at time t, It is used to represent the peak-to-peak distance of adjacent interference peaks obtained after converting the spectrum obtained by the first optical resonator based on the laser bandwidth from the wavelength domain to the frequency domain, c is used to represent the speed of light, and n c1 Used to represent the refractive index coefficient of the first optical resonant cavity.

[0037] Optionally, the reflectivity of the first surface of the optical cavity layer is selected from [R th_2 , R th_3 ], where R th_2 Used to represent the second reflectivity threshold, R th_3 is used to represent the third reflectivity threshold, and R th_2 ≤R th_3 ≤R th_1 , wherein a second optical resonant cavity is formed in the optical cavity layer material between the first surface of the optical cavity layer and the second surface of the optical cavity layer; the method further comprises: determining an initial temperature When the distance between the first surface of the optical cavity layer and the second surface of the optical cavity layer is ; Determine the time to be detected The distance between the first surface of the optical cavity layer and the second surface of the optical cavity layer ; Use the following formula to determine the time to be detected Temperature :

[0038] ;

[0039] in, It is used to represent the linear expansion coefficient of the optical cavity layer material, is the initial temperature, is the initial temperature When the distance between the first surface of the optical cavity layer and the second surface of the optical cavity layer, is the distance between the first surface of the optical cavity layer and the second surface of the optical cavity layer at the time t to be detected.

[0040] Optionally, to solve the above technical problems, an embodiment of the present invention provides an optical coupling packaging combination, comprising: a semiconductor structure as described above; a base, on which the semiconductor structure is mounted; an optical fiber, used to input a laser signal of a laser; an optical collimator, a first end of the optical collimator is coupled to the optical fiber, and is used to collimate the received laser signal to the second end of the optical collimator; a pluggable structure, a first component of the pluggable structure is pluggably coupled to the second end of the optical collimator, and a second component of the pluggable structure is coupled to the semiconductor structure, so that the laser signal output by the second end of the optical collimator vertically enters the first surface of the optical cavity layer; wherein the first component and the second component of the pluggable structure are pluggably connected.

[0041] Optionally, the pluggable structure includes: a coaxial nut, a first end of which is coupled to the second end of the optical collimator; a top shell, which is mounted on the base and has a hollow chamber for accommodating the semiconductor structure between the top shell and the base, and the top shell has a coaxial screw hole that is adapted to the coaxial nut; wherein the central axis direction of the connected coaxial nut and the coaxial screw hole is consistent with the direction of the laser signal output by the optical collimator.

[0042] Optionally, the pluggable structure includes: an FC / PC connector, a first end of the FC / PC connector being pluggably coupled to a second end of the optical collimator; a top shell, the top shell being mounted on the base and having a hollow chamber for accommodating the semiconductor structure between the top shell and the base, the top shell having an FC / PC connector interface adapted to the FC / PC connector; wherein, after the FC / PC connector is connected to the FC / PC connector interface, the transmission direction of the laser signal thereof is consistent with the direction of the laser signal output by the optical collimator.

[0043] Optionally, the optical coupling packaging combination further includes one or more of the following: an optical cable, wrapped around the outside of the optical fiber; a protective tail sleeve, a first end of the protective tail sleeve being sleeved on the outside of the optical cable, and a second end of the protective tail sleeve being connected to a first end of a coaxial nut or an FC / PC connector; a crimping ring, a first end of the crimping ring being coupled to the optical cable, and a second end of the crimping ring being connected to a first end of the optical collimator.

[0044] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0045] In an embodiment of the present invention, a semiconductor structure is designed, which has an optical cavity layer and a resonance layer, and the resonance layer includes a mass block that can vibrate in a direction perpendicular to the first surface of the resonance layer. A first optical resonance cavity can be formed between the second surface of the optical cavity layer and the surface of the mass block facing the second surface of the optical cavity layer, so that the parameters (such as inertial force or displacement) of the mass block can be measured by laser signals, which helps to improve the anti-electromagnetic interference capability and has application advantages in extreme environments. In addition, the cavity length of the first optical resonance cavity is determined by the first frequency based on the minimum wavelength of the laser bandwidth and the second frequency based on the maximum wavelength of the laser bandwidth. Since the spectrum obtained based on the laser bandwidth is in a non-uniform state in the wavelength domain, the peak-to-peak distances of adjacent interference peaks are inconsistent and the difference is large. In contrast, after the spectrum obtained based on the laser bandwidth is converted from the wavelength domain to the frequency domain, the peak-to-peak distances of adjacent interference peaks obtained can be kept consistent. Therefore, the cavity length of the first optical resonance cavity is determined according to the first frequency and the second frequency. Compared with using a preset fixed cavity length, or compared with determining the cavity length of the first optical resonance cavity based on the wavelength of the spectrum, the cavity length of the first optical resonance cavity can be determined more accurately, effectively improving the precision of subsequent acceleration detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a schematic cross-sectional structural diagram of a semiconductor structure in an embodiment of the present invention;

[0047] Figure 2 is a schematic diagram of the working principle of a semiconductor structure in an embodiment of the present invention;

[0048] Figure 3 It is a schematic diagram of adjacent interference peaks obtained after converting a spectrum obtained by a first optical resonant cavity based on a laser bandwidth from a wavelength domain to a frequency domain in an embodiment of the present invention;

[0049] Figure 4 is an exploded view of a semiconductor structure in an embodiment of the present invention;

[0050] Figure 5 is a flow chart of an acceleration detection method in an embodiment of the present invention;

[0051] Figure 6 is a partial flow chart of another acceleration detection method in an embodiment of the present invention;

[0052] Figure 7 is an exploded view of an optical coupling package assembly according to an embodiment of the present invention;

[0053] Figure 8It is a partial exploded view of another optical coupling package combination in an embodiment of the present invention.

[0054] Description of reference numerals:

[0055] A first reflective film 101, a first anti-reflective film 103, a second reflective film 201, a mass block 202, an elastic connecting component 203, a second anti-reflective film 204, a frame 205, a third anti-reflective film 301, an optical fiber 701, an optical cable 702, an optical collimator 703, a crimping ring 704, a protective tail sleeve 705, a coaxial nut 706, a coaxial screw hole 707, a recess 708, a top shell 709, a semiconductor structure 710, a limit frame 711, a chip platform 712, a gasket 713, a base 714, a fastening surface 715, a screw hole 716, a bolt 717, an FC / PC connector 801, an FC / PC connector interface 802, a through hole 803, and a top shell 804. DETAILED DESCRIPTION

[0056] As mentioned above, existing electrical acceleration sensors often have common defects, and existing optical acceleration sensors often have poor accuracy in detecting parameters such as acceleration.

[0057] Specifically, to measure the quality of an accelerometer, it is often necessary to comprehensively consider multiple working parameters, such as one or more of the following: frequency response bandwidth, high g value (acceleration measurement amplitude), shock resistance, resolution, linearity, long-term stability, sensitivity temperature stability, zero drift temperature stability and operating temperature range.

[0058] After research, it was found that for the existing electrical acceleration sensors, piezoelectric technology has very good parameters in frequency response bandwidth, high g value, shock resistance, and linearity, but the performance in other parameters is very weak; piezoresistive technology is similar to piezoelectric technology, but lacks in frequency response bandwidth; on the contrary, capacitance technology is very good in resolution, linearity, long-term stability, sensitivity temperature stability, and zero drift temperature stability, and other parameters are mediocre. However, electrical measurement technologies have some common defects. Since they belong to active detection, in very harsh environments, such as high electromagnetic, high current, high voltage, electrostatic dust, flammable and explosive, extreme temperature (such as less than -50℃ and higher than 120℃), the signal performance is poor signal-to-noise ratio, and even cannot perform effective detection work.

[0059] For existing optical acceleration sensors, although fiber Bragg grating technology is a passive sensing technology with strong anti-electromagnetic interference capabilities and can also be used in environments such as electrostatic dust, flammable and explosive materials, and extreme temperatures, as a sensitive element of the acceleration sensor, it cannot be compared with electrical sensing methods in terms of the above-mentioned parameters.

[0060] In addition, laser dynamic ranging technology and optical flow field technology are subject to interference from ambient light pollution, and are therefore only suitable for measuring short distances and light-free indoor environments or air-permeable outdoor environments, and are not suitable for acceleration detection that requires high precision.

[0061] In an embodiment of the present invention, a semiconductor structure is designed, which has an optical cavity layer and a resonance layer, and the resonance layer includes a mass block that can vibrate in a direction perpendicular to the first surface of the resonance layer. A first optical resonance cavity can be formed between the second surface of the optical cavity layer and the surface of the mass block facing the second surface of the optical cavity layer, so that the parameters (such as inertial force or displacement) of the mass block can be measured by laser signals, which helps to improve the anti-electromagnetic interference capability and has application advantages in extreme environments. In addition, the cavity length of the first optical resonance cavity is determined by the first frequency based on the minimum wavelength of the laser bandwidth and the second frequency based on the maximum wavelength of the laser bandwidth. Since the spectrum obtained based on the laser bandwidth is in a non-uniform state in the wavelength domain, the peak-to-peak distances of adjacent interference peaks are inconsistent and the difference is large. In contrast, after the spectrum obtained based on the laser bandwidth is converted from the wavelength domain to the frequency domain, the peak-to-peak distances of adjacent interference peaks obtained can be kept consistent. Therefore, the cavity length of the first optical resonance cavity is determined according to the first frequency and the second frequency. Compared with using a preset fixed cavity length, or compared with determining the cavity length of the first optical resonance cavity based on the wavelength of the spectrum, it can be more accurate and effectively improve the precision of subsequent acceleration detection.

[0062] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0063] Reference Figure 1 , Figure 1 1 is a schematic cross-sectional view of a semiconductor structure in an embodiment of the present invention. The semiconductor structure may include an optical cavity layer and a resonance layer, and may also include a capping layer.

[0064] The laser signal may enter from the first surface of the optical cavity layer, and the second surface of the optical cavity layer may have a first reflective film 101 .

[0065] The first surface of the resonance layer faces the second surface of the optical cavity layer, wherein the resonance layer may include: a mass block 202 .

[0066] The mass block 202 can vibrate in a direction perpendicular to the first surface of the resonance layer, and a second reflective film 201 may be provided on the surface of the mass block 202 facing the second surface of the optical cavity layer, so that a first optical resonance cavity is formed between the second surface of the optical cavity layer and the surface of the mass block 202 facing the second surface of the optical cavity layer.

[0067] It can be understood that when a light wave (such as a laser signal) enters the first optical resonant cavity, the incident light wave and the reflected light wave interfere with each other, and after multiple reciprocating reflections on the cavity mirrors at both ends, the multiple light beams interfere to form a standing wave.

[0068] The cavity length of the first optical resonant cavity is the distance between two reflective mirrors (eg, the first reflective film 101 and the second reflective film 201 ).

[0069] It should be pointed out in particular that Figure 1 The cavity length of the first optical resonant cavity in is used to represent the absolute cavity length, that is, the cavity length of the first optical resonant cavity when the mass block is stationary, which can also be called the effective cavity length.

[0070] The laser signal forms a comb-shaped spectrum in the first optical resonant cavity, and the cavity length of the first optical resonant cavity is determined by a first frequency based on a minimum wavelength of the laser bandwidth and a second frequency based on a maximum wavelength of the laser bandwidth.

[0071] Combined with reference Figure 2 and Figure 3 , Figure 2 is a schematic diagram of the working principle of a semiconductor structure in an embodiment of the present invention, Figure 3 It is a schematic diagram of adjacent interference peaks obtained after a spectrum obtained by a first optical resonant cavity based on a laser bandwidth in an embodiment of the present invention is converted from a wavelength domain to a frequency domain.

[0072] exist Figure 2 In the first optical resonant cavity formed between the second surface of the optical cavity layer and the surface of the mass block facing the second surface of the optical cavity layer, since the second surface of the optical cavity layer has a first reflective film, and the surface of the first surface of the resonant layer has a second reflective film, the first optical resonant cavity is essentially a Fabry-Pérot Cavity (F-PCavity), which can also be referred to as a Fabry-Pérot cavity. Based on the Fabry-Pérot cavity interferometry method, the measurement of the absolute cavity length change with high sensitivity and low uncertainty is achieved.

[0073] It should be particularly pointed out that, in some embodiments, the optical cavity layer material between the first surface of the optical cavity layer and the second surface of the optical cavity layer can also form a second optical resonant cavity, thereby forming an adjacent double Fabry-Perot cavity.

[0074] In a specific embodiment, appropriate materials may be selected to form the optical cavity layer, the resonance layer, and the capping layer.

[0075] It should be pointed out that in order to reduce process complexity, the optical cavity layer, the resonance layer and the capping layer can be formed on the same material using a semiconductor manufacturing process. In other words, the optical cavity layer, the resonance layer and the capping layer can be formed using the same material.

[0076] In some embodiments, the material may include one or a combination of the following: silicon, germanium, silicon germanium, silicon carbide, gallium arsenide, indium gallium, gallium nitride, aluminum oxide, sapphire material, etc.

[0077] Taking silicon as an example, the type of the second optical resonant cavity may be a silicon-based resonant cavity, and the type of the first optical resonant cavity may be a vacuum or air resonant cavity.

[0078] exist Figure 2 In a specific embodiment shown, the laser signal may be arranged to be emitted vertically toward the semiconductor structure, and thereby enter the interior of the semiconductor structure.

[0079] Specifically, the laser signal may have a spectral range of, for example, 1520 nm to 1580 nm, and may also be beamed and enter from the first surface of the optical cavity layer.

[0080] Vertical emission into the semiconductor structure can be achieved through optical fibers with collimation and coupling functions.

[0081] Specifically, the laser signal can first pass through the silicon-based resonant cavity (i.e., the second optical resonant cavity) and then pass through the air resonant cavity (i.e., the first optical resonant cavity). The light forms multiple round-trip reflections inside the silicon-based resonant cavity and the air resonant cavity respectively, and each transmits the optical signal carrying temperature information and acceleration information (vibration information) back along the original path through the optical cavity layer in the opposite direction.

[0082] In a specific embodiment, the optical signal can be reflected back to the collimated coupling optical fiber, and the optical signal in which the temperature and acceleration information are superimposed on each other can be captured by a photodetector, and the real physical quantities, namely temperature and acceleration, can be finally restored through a certain demodulation and decoupling algorithm.

[0083] exist Figure 2 The double Fabry-Perot cavity with fixed mirrors is shown. The reflectivity and transmittance can be set as and Its main function is to optically couple the incident light or reflected light with the external waveguide medium, that is, the receiving and feedback end face of the optical signal.

[0084] Sensitive mirror The reflectivity and transmittance can be set as and , which is related to the sensitive mirror Together they form a FP interferometer cavity , the cavity length is .Should The main function of the cavity is to be sensitive to acceleration (vibration) and insensitive to temperature. The change of acceleration Change and change.

[0085] Sensitive mirror The reflectivity and transmittance can be set as and , which is related to the fixed mirror Together they form a FP interferometer cavity , the cavity length is .Should The main function of the cavity is to be sensitive to temperature and insensitive to acceleration, that is, the cavity length The change of the amount of temperature Change and change.

[0086] In the subsequent steps, a laser signal (such as broadband light or a continuously tunable laser) is set to be emitted from the fixed mirror. Entering the double FP interferometer cavity, you can measure the fixed mirror The reflected light from the surface or through the sensitive lens The transmitted light from the FP cavity is used to demodulate and FP cavity The optical superposition signal is used to calculate the acceleration signal and the temperature signal respectively.

[0087] Combined with reference Figure 3 , laser signals (such as broadband light or continuously tunable lasers) have a laser bandwidth .

[0088] After research, it was found that in the laser bandwidth If the wavelength of light For the analysis object, the wavelength of light is used As the horizontal axis, the light intensity I is used as the vertical axis for analysis. The obtained curve does not show a regular period. In other words, based on the wavelength of light The obtained curve has inconsistent peak-to-peak distances and appears to be uneven in size.

[0089] Further research found that in this case, the wavelength of light The change in the amount of change and the change in the physical quantity are not linear, there will be certain errors in the subsequent calculations, and they will continue to accumulate.

[0090] In the laser bandwidth If the spectrum is converted from wavelength domain to frequency domain, the optical frequency For the analysis object, Figure 3 As shown, the optical frequency As the horizontal axis, the light intensity I is used as the vertical axis for analysis, and the obtained curve can show a regular period. In other words, based on the light frequency The obtained curve and adjacent interference peaks have the same peak-to-peak distance, which can also be called the free space range (FSR) is equal.

[0091] When the laser signal enters the FP cavity, the wavelength that satisfies the following formula can form an interference peak, that is, the optical path is an integer multiple of half the wavelength:

[0092] (1);

[0093] Among them, n c is the refractive index coefficient of the FP Fabry-Perot cavity, is the length of the FP Fabry-Perot cavity, it can be inferred that, is the optical path of the Fabry-Perot cavity.

[0094] in, is the cavity modulus; is the interference peak wavelength corresponding to the cavity mode number.

[0095] In addition, the speed of light, light frequency and light wavelength satisfy the following formula:

[0096] (2);

[0097] in, is the speed of light, is the light frequency, is the wavelength of light.

[0098] Combining formula (1) and (2), we can get the following formula:

[0099] (3);

[0100] In the formula (3) derived from the embodiment of the present invention, the absolute cavity length of the FP cavity is demodulated by using the FSR within the optical frequency, and then the corresponding physical quantity (such as acceleration, etc.) is solved, so that the data can be more accurate.

[0101] Further research found that based on the frequency of light The curve obtained and the adjacent interference peaks obtained have the same peak-to-peak distance. This inference can lead to the following formula:

[0102] (4);

[0103] in, For the spectrum Figure 3 The “peak-to-peak distance” between adjacent interference peaks in the frequency domain is shown.

[0104] From formula (4), we can see that when the length of the FP Fabry-Perot cavity is When a certain are equal.

[0105] When the length of the FP Fabry-Perot cavity is Grow to hour, becomes smaller; on the contrary, The value of becomes larger.

[0106] The corresponding The optical frequency of the interference peak of the cavity mode number is also shifted at the same time.

[0107] No need to solve Cavity module and corresponding The frequency shift of the interference peak How much is it? Just ask , the absolute cavity length of the FP Fabry-Perot cavity can be calculated It should be noted that the absolute cavity length of the FP cavity is It can be used to indicate the cavity length of the optical resonant cavity when the mass block is stationary, and is also called the effective cavity length.

[0108] For laser bandwidth , can be expressed using the laser bandwidth wavelength to obtain the following formula:

[0109] (5);

[0110] in, is the minimum wavelength of the laser bandwidth, is the maximum value of the laser bandwidth wavelength.

[0111] After converting the laser bandwidth from the wavelength domain to the frequency domain, the frequency domain bandwidth of the laser can be expressed by the following formula:

[0112] (6);

[0113] in, is the frequency domain bandwidth of the laser, is the speed of light, is the minimum wavelength of the laser bandwidth, is the maximum value of the laser bandwidth wavelength.

[0114] After further research, it was found that in order to determine the absolute cavity length, it is necessary to ensure that at least one , specifically, it can be expressed by the following formula:

[0115] (7);

[0116] Substitution , we can get the following formula:

[0117] (8);

[0118] Then we can derive the following formula:

[0119] (9);

[0120] Continue to refer to Figure 1 , the laser signal forms a comb-shaped spectrum in the first optical resonant cavity, and the cavity length of the first optical resonant cavity is It is determined by a first frequency based on the minimum wavelength of the laser bandwidth and a second frequency based on the maximum wavelength of the laser bandwidth.

[0121] As mentioned above, it has been found that in the laser bandwidth If the wavelength of light For the analysis object, the wavelength of light is used As the horizontal axis, the light intensity I is used as the vertical axis for analysis. The obtained curve does not show a regular period. In other words, based on the wavelength of light The peak-to-peak distances of the obtained curve are not consistent, showing uneven sizes. In this case, the wavelength of light The change in the amount of change and the change in the physical quantity are not linear, there will be certain errors in the subsequent calculations, and they will continue to accumulate.

[0122] In the laser bandwidth If the spectrum is converted from wavelength domain to frequency domain, the optical frequency For the analysis object, Figure 3 As shown, the optical frequency As the horizontal axis, the light intensity I is used as the vertical axis for analysis, and the obtained curve can show a regular period. In other words, based on the light frequency The obtained curve and adjacent interference peaks have the same peak-to-peak distance, which can also be called equal FSR.

[0123] Therefore, using the FSR within the optical frequency to demodulate the absolute cavity length of the FP cavity and then solving the corresponding physical quantities (such as acceleration, etc.) can make the data more accurate.

[0124] In an embodiment of the present invention, a semiconductor structure is designed, which has an optical cavity layer and a resonance layer, and the resonance layer includes a mass block that can vibrate in a direction perpendicular to the first surface of the resonance layer. A first optical resonance cavity can be formed between the second surface of the optical cavity layer and the surface of the mass block facing the second surface of the optical cavity layer, so that the parameters (such as inertial force or displacement) of the mass block can be measured by laser signals, which helps to improve the anti-electromagnetic interference capability and has application advantages in extreme environments. In addition, the cavity length of the first optical resonance cavity is determined by the first frequency based on the minimum wavelength of the laser bandwidth and the second frequency based on the maximum wavelength of the laser bandwidth. Since the spectrum obtained based on the laser bandwidth is in a non-uniform state in the wavelength domain, the peak-to-peak distances of adjacent interference peaks are inconsistent and the difference is large. In contrast, after the spectrum obtained based on the laser bandwidth is converted from the wavelength domain to the frequency domain, the peak-to-peak distances of adjacent interference peaks obtained can be kept consistent. Therefore, the cavity length of the first optical resonance cavity is determined according to the first frequency and the second frequency. Compared with using a preset fixed cavity length, or compared with determining the cavity length of the first optical resonance cavity based on the wavelength of the spectrum, it can be more accurate and effectively improve the precision of subsequent acceleration detection.

[0125] Furthermore, based on the above formula (8), the refractive index coefficient of the first optical resonant cavity can be substituted into , the cavity length of the first optical resonant cavity is obtained as follows:

[0126] (10);

[0127] in, It is used to represent the cavity length of the first optical resonant cavity, The first frequency used to represent the minimum wavelength based on the laser bandwidth, A second frequency used to represent the maximum wavelength based on the laser bandwidth and c is used to represent the speed of light.

[0128] Furthermore, based on the above formula (9), the refractive index coefficient of the first optical resonant cavity can be substituted into , the cavity length of the first optical resonant cavity is obtained as follows:

[0129] (11);

[0130] in, It is used to represent the cavity length of the first optical resonant cavity, Used to represent the refractive index coefficient of the first optical resonant cavity.

[0131] In a specific implementation, the cavity length of the first optical resonant cavity is calculated by formula (10) or (11), and the first frequency and the second frequency of the laser bandwidth can be used to calculate the characteristics of the spectrum obtained based on the laser bandwidth after converting from the wavelength domain to the frequency domain, which helps to obtain a more accurate cavity length.

[0132] In a specific implementation, the first surface of the optical cavity layer may have a certain transmittance, so that more laser signals are transmitted into the semiconductor structure.

[0133] More specifically, in the first implementation, the first surface of the optical cavity layer may have a first anti-reflection film 103 ; the transmittance of the first anti-reflection film 103 is greater than or equal to a first transmittance threshold.

[0134] In a specific example of the first implementation manner, the first transmittance threshold may be greater than or equal to 50%.

[0135] In the embodiment of the present invention, by setting the first surface of the optical cavity layer to have a certain transmittance, more laser signals can be transmitted into the semiconductor structure.

[0136] More specifically, instead of depositing a semi-reflective (SR) coating on the upper surface of the semiconductor structure, an anti-reflective (AR) coating is deposited, and most of the light beam (e.g., close to 100%) enters the silicon wafer, thus fixing the reflector. Disappeared, unable to form FP cavity , so it is impossible to measure temperature. However, a fiber Bragg grating (FBG) can be engraved in the fiber core of the fiber collimator patch cord as a sensor for measuring temperature.

[0137] In a specific implementation, the second surface of the optical cavity layer and the first surface of the resonance layer may have a certain reflectivity, thereby providing a basis for forming the first optical resonance cavity.

[0138] More specifically, in the second embodiment, the reflectivity of the first reflective film 101 may be greater than or equal to a first reflectivity threshold R th_1 ; and / or, the second reflective film 201 is greater than or equal to the first reflectivity threshold R th_1 .

[0139] In the embodiment of the present invention, by setting the second surface of the optical cavity layer and the first surface of the resonance layer to have a relatively large reflectivity, a good foundation can be provided for forming the first optical resonance cavity.

[0140] Specifically, by depositing a dielectric coating having a high reflection (HR) function on the first surface of the mass block 202 of the resonant layer, a Figure 3 The sensitive mirror Mir1 is shown.

[0141] In the specific implementation, in order to obtain a high-precision interference peak, the reflectivity of the sensitive mirror Mir1 can be set and transmittance and the reflectivity of the optical cavity layer sensitive mirror Mir2 and transmittance Equal, for example is 90%, is 10%.

[0142] In a specific example of the second embodiment, the reflectivity of the first surface of the optical cavity layer is selected from [R th_2 , R th_3 ], where R th_2 Used to represent the second reflectivity threshold, R th_3 is used to represent the third reflectivity threshold, and R th_2 ≤R th_3 ≤R th_1 ; Wherein, a second optical resonant cavity is formed in the optical cavity layer material between the first surface of the optical cavity layer and the second surface of the optical cavity layer.

[0143] Specifically, due to R th_2 ≤R th_3 ≤R th_1 Therefore, by setting the reflectivity of the first surface of the optical cavity layer to be smaller and the reflectivity of the second surface of the optical cavity layer to be larger, the laser signal returning to the first surface of the optical cavity layer after being reflected inside the semiconductor structure can be emitted to the outside of the semiconductor structure more, thereby avoiding signal clutter caused by too many reflection rounds.

[0144] In some embodiments, the solution that the reflectivity of the first surface of the optical cavity layer is lower than the reflectivity of the second surface of the optical cavity layer can be achieved by not providing a reflective film on the first surface of the optical cavity layer.

[0145] Specifically, the material of the optical cavity layer may be a silicon-based material, and the first surface of the optical cavity layer may not have a reflective film or an anti-reflective film.

[0146] It should be noted that, unlike the first embodiment in which the first surface of the optical cavity layer has a first anti-reflection film, the first surface of the optical cavity layer may have neither a reflective film nor an anti-reflection film. In other words, the reflective / transmissive properties of the silicon-based material surface may be directly used.

[0147] Specifically, the upper surface of the semiconductor structure does not deposit a semi-reflective (SR) coating, but uses the interface between the polished silicon surface and the air as a fixed mirror. .

[0148] In a silicon-based material, its reflectivity About 30%, transmittance About 70%.

[0149] In the embodiment of the present invention, by not providing a reflective film or an anti-reflective film on the first surface of the optical cavity layer, the reflective / transmittance characteristics of the silicon-based material surface can be used to meet device requirements while reducing process complexity and process cost.

[0150] In other embodiments, the solution that the reflectivity of the first surface of the optical cavity layer is lower than the reflectivity of the second surface of the optical cavity layer can be achieved by providing a reflective film with lower reflectivity on the first surface of the optical cavity layer.

[0151] Specifically, the first surface of the optical cavity layer may have a third reflective film (not shown), and the reflectivity of the third reflective film may be [R th_2 , R th_3 ].

[0152] As mentioned above, R th_2 ≤R th_3 ≤R th_1 Therefore, by setting an appropriate third reflective film, the requirement that the reflectivity of the first surface of the optical cavity layer is relatively small and the reflectivity of the second surface of the optical cavity layer is relatively large can be met.

[0153] It should be noted that, in one embodiment, the third reflective film and the first anti-reflective film 103 can be disposed simultaneously on the first surface of the optical cavity layer; in another embodiment, a single-layer film can also be disposed on the first surface of the optical cavity layer, and the single-layer film can simultaneously satisfy the reflectivity of [R th_2 , R th_3 ] and the transmittance is greater than or equal to the first transmittance threshold. In the embodiment of the present invention, there is no specific restriction on the number of film layers on the first surface of the optical cavity layer.

[0154] In the embodiment of the present invention, the laser signal returning to the first surface of the optical cavity layer after being reflected inside the semiconductor structure can be emitted to the outside of the semiconductor structure more, thereby avoiding signal clutter due to too many reflection rounds.

[0155] Regarding the second optical resonant cavity, the above and Figure 3 The laser signal enters from the first surface of the optical cavity layer, a part of it is emitted from the second surface of the optical cavity layer and enters the first surface of the resonance layer, and a part of it is not emitted from the second surface of the optical cavity layer, forming a comb-shaped spectrum in the second optical resonance cavity.

[0156] Furthermore, based on the above formula (8), the refractive index coefficient of the second optical resonant cavity can be substituted into , the cavity length of the second optical resonant cavity is obtained as follows:

[0157] (12);

[0158] in, is used to represent the cavity length of the second optical resonant cavity, The first frequency used to represent the minimum wavelength based on the laser bandwidth, A second frequency used to represent the maximum wavelength based on the laser bandwidth and c is used to represent the speed of light.

[0159] Furthermore, based on the above formula (9), the refractive index coefficient of the second optical resonant cavity can be substituted into , the cavity length of the second optical resonant cavity is obtained as follows:

[0160] (13);

[0161] in, is used to represent the cavity length of the second optical resonant cavity, c is used to represent the speed of light, and λ min Minimum wavelength used to express the bandwidth of a laser, λ max Used to express the maximum wavelength of the laser bandwidth, is used to represent the refractive index coefficient of the second optical resonant cavity.

[0162] In a specific implementation, the cavity length of the second optical resonant cavity is calculated by formula (12) or (13), and the first frequency and the second frequency of the laser bandwidth can be used. The calculation is based on the characteristics of the spectrum obtained from the laser bandwidth after being converted from the wavelength domain to the frequency domain, which helps to obtain a more accurate cavity length.

[0163] Reference Figure 4 , Figure 4 is an exploded view of a semiconductor structure in an embodiment of the present invention. Figure 4 and Figure 1 Different contents are explained.

[0164] exist Figure 4 In the semiconductor structure shown, an optical cavity of the semiconductor structure can be formed between the second surface of the optical cavity layer and the first surface of the capping layer. The mass block 202 can vibrate in the optical cavity driven by the elastic connecting component 203 .

[0165] The resonance layer may include: a frame 205; a plurality of elastic connection components 203, wherein the plurality of elastic connection components 203 are symmetrically connected to the inner sides of the frame 205; the mass block 202 is suspended from the frame through the elastic connection components 203 and is surrounded by the frame 205; wherein the mass block 202 can vibrate in a direction perpendicular to the first surface of the resonance layer under the drive of the elastic connection components 203.

[0166] In a specific implementation, by driving the mass block 202 with the elastic connection component 203 to vibrate in a direction perpendicular to the first surface of the resonance layer, the mass block 202 can move back and forth in the optical cavity of the semiconductor structure, thereby realizing the resonance function of the resonance device.

[0167] Furthermore, the plurality of elastic connection components 203 include at least two groups of elastic connection components 203 that are distributed in a mirror image; wherein the mirror image planes of the two groups of elastic connection components 203 are parallel to the plane where the frame 205 is located.

[0168] Specifically, the elastic connection component 203 can also be called a resonance beam according to its function. The mass block and the resonance beam structure of the resonance layer can be obtained by etching on a double-sided polished silicon wafer.

[0169] By making the mirror planes of the two sets of elastic connection components 203 parallel to the plane where the frame 205 is located, it can be achieved that the resonance beam includes two layers, the upper beam pattern structure and the lower beam pattern structure are distributed in mirror symmetry.

[0170] In the embodiment of the present invention, by making the mirror planes of the two sets of elastic connecting components 203 parallel to the plane where the frame 205 is located, a design of an upper and lower double-layer resonant beam can be obtained, which effectively reduces the sensitivity of the lateral displacement (such as the direction parallel to the surface of the mass block 202) of the mass block in the acceleration sensor chip, and ensures that the mass block only performs reciprocating motion (also known as piston motion) in the axial direction perpendicular to the surface of the mass block 202 (that is, the vibration direction of the acceleration sensor chip).

[0171] It should be noted that the elastic connecting component 203 may not adopt a two-layer structure, but a single-layer structure.

[0172] Furthermore, the elastic connecting component 203 is curved or folded, and may include one or more of the following: the elastic connecting component 203 is an I-shaped folded line; the elastic connecting component 203 is a T-shaped folded line; the elastic connecting component 203 is an S-shaped folded line; the elastic connecting component 203 is a W-shaped folded line; the elastic connecting component 203 is an L-shaped folded line; the elastic connecting component 203 is an X-shaped folded line; the elastic connecting component 203 is an M-shaped folded line; the elastic connecting component 203 is a hollow structure.

[0173] Taking the elastic connection component 203 as an S-shaped broken line as an example, the projection pattern of each group of elastic connection components 203 in the two groups of elastic connection components 203 on the parallel surface of the first surface of the resonance layer is "S"-shaped; each group of elastic connection components 203 includes a plurality of first beams arranged in parallel, a second beam connecting adjacent first beams, and a third beam connecting the first beams and the inertial mass block.

[0174] Taking the elastic connection component 203 in the form of an I-shaped broken line as an example, the projection pattern of each group of the two groups of elastic connection components 203 on the plane parallel to the first surface of the resonance layer is a strip.

[0175] The shapes of various elastic connecting components 203 including the "I" shape and "S" shape have better buffering effect in the horizontal direction, and have the characteristics of high sensitivity, high linearity, and strong resistance to lateral interference, thereby improving the sensitive structure's resistance to lateral vibration interference and impact damage; in addition, the elastic connecting component 203 structure of this shape is more suitable for production using semiconductor process technology.

[0176] The high sensitivity means that under the action of a force perpendicular to the surface of the mass block 202, the mass block 202 is prone to displacement and deformation in the vertical direction perpendicular to the surface of the mass block 202; the strong anti-lateral interference ability means that under the action of a force parallel to the surface of the mass block 202, the mass block 202 has a large rigidity and is not prone to displacement and deformation.

[0177] It should be noted that the shape of the elastic connecting member 203 can be more complex, such as Figure 4 As shown, it can be presented as a combination of multiple types of broken lines. The embodiment of the present invention is not limited to a single broken line shape.

[0178] In some embodiments, the frame, the plurality of elastic connection components, and the mass block are an integrally formed structure formed by a semiconductor manufacturing process.

[0179] In some embodiments, the resonant layer is formed based on a semiconductor substrate after double-sided polishing. The semiconductor substrate is a silicon wafer as an example for description below.

[0180] Specifically, the formation process of the resonance layer may include: providing a silicon wafer, performing double-sided polishing on the silicon wafer, and etching on the silicon wafer obtained after the double-sided polishing to obtain the resonance layer. It can be understood that when the resonance layer is obtained, the frame 205, the plurality of elastic connection components 203 and the mass block 202 are also obtained.

[0181] In a specific embodiment, the second surface of the resonance layer may have a second anti-reflection film 204 (see Figure 1 ), wherein the transmittance of the second anti-reflection film 204 may be greater than or equal to a second transmittance threshold.

[0182] In a specific implementation, the second transmittance threshold may be set to 50%, that is, the transmittance of the second anti-reflection film 204 may be greater than or equal to 50%.

[0183] Specifically, a dielectric coating with an anti-reflection (AR) function, i.e., a second anti-reflection film 204, is formed on the lower surface of the resonant layer mass block, so that the light beam transmitted through the sensitive mirror Mir1 can be completely transmitted through the mass block 202 after passing through the mass block 202, thereby not generating obvious interface reflection, thereby avoiding the formation of a third resonant cavity and controlling the complexity of implementation.

[0184] In some embodiments, the second surface of the optical cavity layer may have a first recessed portion, and the bottom surface of the first recessed portion is a plane; wherein the first reflective film may be located on the bottom surface of the recessed portion; and the projection of the mass block 202 on the second surface of the optical cavity layer is within the bottom surface of the first recessed portion.

[0185] In some embodiments, the optical cavity layer is formed based on a semiconductor substrate after double-sided polishing. The semiconductor substrate is a silicon wafer as an example for description below.

[0186] Specifically, the process for forming the optical cavity layer may include: providing a silicon wafer, performing double-side polishing on the silicon wafer, and etching on the silicon wafer obtained after the double-side polishing to obtain the optical cavity layer.

[0187] More specifically, a concave plane may be etched on the lower surface (ie, the second surface) of the double-sided polished silicon wafer.

[0188] Furthermore, the surface of the concave plane may be a smooth surface, thereby improving the direction controllability of the reflected light signal.

[0189] A dielectric coating having a semi-reflective (SR) function, namely a first anti-reflective film 103 (see Figure 1 ), such as the formation of reflectivity is 50%, that is, the transmittance Also 50% of the fixed mirror Mir0.

[0190] A dielectric coating having a high reflection (HR) function, namely, a first reflection film 101 (refer to Figure 1 ), forming a sensitive mirror Mir2, such as reflectivity The transmittance is 90%. is 10%.

[0191] The semi-reflective (SR) dielectric coating on the upper surface of the double-sided polished silicon wafer (fixed mirror Mir0) and the HR high-reflective dielectric coating on the concave plane (sensitive mirror Mir2) form a FP cavity with silicon as the medium. , the cavity length is approximately the difference between the thickness of the double-sided polished silicon wafer and the etching depth, defined as .

[0192] The high-reflection (HR) dielectric coating (sensitive mirror Mir2) on the concave plane of the silicon-based optical cavity layer and the high-reflection (HR) dielectric coating (sensitive mirror Mir1) on the upper surface of the mass block of the silicon-based resonant layer form an FP cavity with air as the medium. , whose cavity length is approximately the etching depth, defined as .

[0193] In the embodiment of the present invention, by forming a first recessed portion on the second surface of the optical cavity layer, and the bottom surface of the first recessed portion is a plane, the first recessed portion can be used to make the formed optical cavity have a larger space to meet the demand for a larger displacement of the mass block 202, and by making the bottom surface of the first recessed portion a plane, the upper half of the formed optical cavity can have better reflection controllability.

[0194] It should be particularly pointed out that in another implementation of the embodiment of the present invention, a frame structure can be formed between the optical cavity layer and the resonance layer, and then an optical cavity with a larger space is formed by bonding the optical cavity layer and the frame structure respectively, and bonding the resonance layer and the frame structure respectively.

[0195] In some embodiments, the concave surface below the optical cavity layer may not be a plane, but a curved arched concave surface, that is, the FP cavity is composed of a spherical mirror and a plane mirror.

[0196] Combined with reference Figure 1 and Figure 4 The semiconductor structure may further include: a capping layer, wherein a first surface of the capping layer faces a second surface of the resonance layer.

[0197] In some embodiments, the surface roughness of the first surface of the capping layer is greater than or equal to a first surface roughness threshold.

[0198] In a specific embodiment, the first surface roughness threshold may be represented by the surface average roughness Ra and / or the surface root mean square roughness Rq.

[0199] For example, the surface roughness of the first surface of the capping layer may include one or more of the following: Ra≥1 nm, Rq≥1 nm.

[0200] Specifically, due to the greater surface roughness of the first surface of the capping layer, more diffuse reflection can be achieved, effectively avoiding the generation of mirror reflection and the interference of return light signals, and effectively improving the problem of excessive noise inside the semiconductor structure.

[0201] In some embodiments, the first surface of the capping layer and the second surface of the capping layer are both coated with a third anti-reflection film, wherein the transmittance of the third anti-reflection film is greater than or equal to a third transmittance threshold, and the first surface of the capping layer is opposite to the second surface of the capping layer.

[0202] The third transmittance threshold may be selected from 50% to 95%, for example, 80%.

[0203] In a specific implementation, by coating the first surface and the second surface of the capping layer with a film with high transmittance, more laser signals can penetrate the capping layer instead of generating mirror reflection and returning signal interference, thereby effectively improving the problem of excessive noise inside the semiconductor structure.

[0204] In some embodiments, the capping layer is formed based on a semiconductor substrate that has been subjected to single-side polishing, and the first surface of the capping layer is a polished surface. The semiconductor substrate is a silicon wafer as an example for description.

[0205] Specifically, the process for forming the capping layer may include: providing a silicon wafer, performing single-side polishing on a first surface of the silicon wafer, and etching on the surface of the silicon wafer obtained after the single-side polishing to obtain a second recessed portion.

[0206] In a specific embodiment, the first surface of the capping layer has a second recessed portion, and the bottom surface of the second recessed portion is a plane; wherein the surface roughness of the bottom surface of the second recessed portion is greater than or equal to the first surface roughness threshold; the projection of the mass block 202 on the first surface of the capping layer is within the bottom surface of the second recessed portion.

[0207] Specifically, a concave plane (i.e., the second concave portion) can be etched on the upper surface of the single-sided polished silicon wafer. The surface of the concave plane should be rough and should not produce mirror reflection.

[0208] Wherein, by forming the second recessed portion, the lower half of the optical cavity can be formed.

[0209] In an embodiment of the present invention, a second recessed portion is formed on the first surface of the capping layer, and the bottom surface of the second recessed portion is a plane. The second recessed portion can be used to allow the formed optical cavity to have a larger space, thereby satisfying the requirement for a larger displacement of the mass block 202. Furthermore, the bottom surface of the second recessed portion is a plane, so that the lower half of the formed optical cavity can have better reflection controllability.

[0210] It should be particularly pointed out that in another implementation of the embodiment of the present invention, a frame structure can also be formed between the cover layer and the resonance layer, and then an optical cavity with a larger space can be formed by bonding the resonance layer and the frame structure separately, and bonding the cover layer and the frame structure separately.

[0211] In some embodiments, the distance between the second surface of the optical cavity layer and the first surface of the resonance layer is greater than or equal to the maximum displacement amplitude of the mass block 202 .

[0212] Specifically, the depth of the depression is greater than the maximum displacement that the mass block 202 withstands during impact vibration, and the maximum displacement is related to the maximum stress under elastic deformation of the material, the mass of the mass block 202 , and the pattern and structure of the elastic connecting component 203 .

[0213] In an embodiment of the present invention, the optical cavity layer, the resonance layer and the capping layer are bonded together in sequence to form a semiconductor structure, also called a sensor chip, for example, a silicon-based micro-optical mechanical temperature-acceleration (Micro Opto-Mechanical Accelerometer, MOMA) integrated sensor chip.

[0214] It should be pointed out that the semiconductor structure obtained in the embodiment of the present invention is essentially a safe passive sensor chip, which can be used in extremely harsh environments. It has the characteristics of being completely immune to electromagnetics and resistant to extreme high and low temperatures.

[0215] In addition, because it uses semiconductor technology and is based on semiconductor substrates (such as single crystal silicon), the material properties of the chip (such as MOMA integrated sensor chip) are the same as those of electrical micro-electro-mechanical system (MEMS) chips, and the production process can be mass-produced, micro-nano-sized, and has good repeatability. Therefore, as an acceleration sensor, MOMA can be comparable to electrical sensors in the test parameters of the acceleration sensor mentioned above, or even better than them.

[0216] In the embodiment of the present invention, the second optical resonant cavity uses silicon as the medium, and the FP cavity The main function of the FP cavity is to measure temperature. The first optical resonant cavity uses air as the medium. The main function is to measure acceleration, i.e. vibration.

[0217] During bonding, there is no real "vacuum", so there will be some rarefied air in the enclosed area. The measured temperature value can be compensated by the FP cavity The measured acceleration value makes the final demodulated acceleration value more accurate.

[0218] The mass block 202 performs piston-like reciprocating motion within the concave range of the optical cavity layer and the cover layer, so that the air cavity length Change has occurred.

[0219] Reference Figure 5 , Figure 5 1 is a flow chart of an acceleration detection method in an embodiment of the present invention. The acceleration detection method may include steps S51 to S52:

[0220] Step S51: determining a displacement amplitude of the mass block at time t, wherein the mass block vibrates in a direction perpendicular to the first surface of the resonant layer, and the displacement amplitude is used to represent a difference between a position of the mass block at time t and a position when the mass block is in a stationary state;

[0221] Step S52: determining the acceleration of the mass block in a direction perpendicular to the first surface of the resonance layer.

[0222] In the specific implementation of steps S51 to S52, the mass block may vibrate in a direction perpendicular to the first surface of the resonant layer, and determine the displacement amplitude of the mass block at time t. , wherein the mass block vibrates in a direction perpendicular to the first surface of the resonant layer, and the displacement amplitude is It is used to represent the difference between the position of the mass block at time t and the position when it is in a static state; the following formula is used to determine the acceleration of the mass block in the direction perpendicular to the first surface of the resonant layer:

[0223] (14);

[0224] in, For expressing the acceleration, Used to represent the spring constant of the mass, Used to indicate the mass of the mass block, Used to represent the displacement amplitude of the mass block at time t.

[0225] Specifically, when the mass block performs piston-like reciprocating motion in the vibration direction, it can be equivalent to a "mass block-spring" system. Therefore, without considering the temperature factor, the following equation can be expressed:

[0226] (15);

[0227] in, is the mass of the mass block; is the damping coefficient; is the spring constant; For FP cavity The change of cavity length with time, that is, the displacement amplitude of the mass block; is the acceleration value of the MOMA sensor chip changing with time.

[0228] If the (excited) acceleration in the vibration direction tends to be stable, expression (15) can be expressed as:

[0229] (16);

[0230] In some embodiments, the following formula may be used to determine the acceleration of the mass block in a direction perpendicular to the first surface of the resonance layer:

[0231] (17);

[0232] in, For expressing the acceleration, Used to represent the spring constant of the mass, Used to indicate the mass of the mass block, Used to represent the displacement amplitude of the mass block at time t.

[0233] In the semiconductor structure, the FP cavity The value of cavity length over time for:

[0234] (18);

[0235] in, When it is in the static state after bonding (that is, when there is no excitation vibration, ), the effective air cavity length between the optical cavity layer sensitive mirror Mir2 and the resonance layer sensitive mirror Mir1.

[0236] From formula (18), we can see that the displacement amplitude It is used to express the difference between the position of the mass block at time t and the position when it is in a stationary state, which can be expressed as follows:

[0237] (19);

[0238] From formulas (16) to (19), it can be seen that when the mass of the mass block is constant, if the same acceleration value is to be obtained, the spring constant The smaller the value, the more displacement of the semiconductor structure The larger it is, the more sensitive the sensor chip formed by the semiconductor structure will be, and it can be designed into a small-range sensor chip, such as On the contrary, it can be designed into a sensor chip with a large range, such as ± .

[0239] in, is the value of gravity acceleration, .

[0240] In other embodiments, the acceleration value may be determined after temperature compensation to further improve the accuracy of acceleration measurement.

[0241] Specifically, the following formula may be used to determine the acceleration of the mass block in a direction perpendicular to the first surface of the resonance layer:

[0242] (20);

[0243] in, is used to represent the acceleration of the mass block in a direction perpendicular to the first surface of the resonant layer and at the current temperature Temp, It is used to represent the spring constant of the mass block at the current temperature Temp. Used to indicate the mass of the mass block, It is used to represent the displacement amplitude of the mass block at the current temperature Temp at time t. Used to represent FP cavity Absolute cavity length at current temperature Temp.

[0244] It should be noted that the FP cavity The absolute cavity length at the current temperature Temp can be used to represent the cavity length of the first optical resonant cavity when the mass block is stationary, and can also be called the effective cavity length.

[0245] In some specific embodiments, the displacement amplitude of the mass block at time t is determined The steps may include:

[0246] Determine the distance between the first surface of the mass block and the second surface of the optical cavity layer when the mass block is in a stationary state ;

[0247] The displacement amplitude of the mass block at time t is determined using the following formula: :

[0248] (twenty one);

[0249] (twenty two);

[0250] in, It is used to represent the real-time cavity length of the first optical resonant cavity at time t, It is used to represent the peak-to-peak distance of adjacent interference peaks obtained after converting the spectrum obtained by the first optical resonator based on the laser bandwidth from the wavelength domain to the frequency domain, c is used to represent the speed of light, and n c1 Used to represent the refractive index coefficient of the first optical resonant cavity.

[0251] Reference Figure 6 , Figure 6 FIG. 1 is a partial flow chart of another acceleration detection method in an embodiment of the present invention. The another acceleration detection method may include Figure 5 The steps S51 to S52 shown may further include steps S61 to S63:

[0252] Step S61: determining the distance between the first surface of the optical cavity layer and the second surface of the optical cavity layer at the initial temperature;

[0253] Step S62: determining the distance between the first surface of the optical cavity layer and the second surface of the optical cavity layer at the time to be detected;

[0254] Step S63: Determine the temperature at the time to be detected.

[0255] In the specific implementation of steps S61 to S63, the material can be used to change the FP cavity by taking advantage of the "thermal expansion and contraction" response of the material to temperature. Silicon cavity length:

[0256] (twenty three);

[0257] in, is the linear expansion coefficient of single crystal silicon.

[0258] (twenty four);

[0259] After bonding, the optical cavity layer fixed mirror With sensitive mirror At the initial temperature Combining formulas (23) and (24), we finally get the FP cavity The value of cavity length over time , which is the time to be detected The distance between the first surface of the optical cavity layer and the second surface of the optical cavity layer:

[0260] (25);

[0261] is the actual temperature at time t, and from (25) we can get:

[0262] (26);

[0263] in, It is used to represent the linear expansion coefficient of the optical cavity layer material, T0 is the initial temperature, is the initial temperature When the distance between the first surface of the optical cavity layer and the second surface of the optical cavity layer, To be detected The distance between the first surface of the optical cavity layer and the second surface of the optical cavity layer, is the actual temperature at time t.

[0264] In other words, by using optical detection method to demodulate The value of can decouple the The temperature value can further improve accuracy and environmental adaptability compared to the solutions in the prior art.

[0265] Reference Figure 7 , Figure 7 7 is an exploded view of an optical coupling package combination in an embodiment of the present invention. The optical coupling package combination may include: a semiconductor structure 710, a base 714, an optical fiber 701, an optical collimator 703 and a pluggable structure.

[0266] The semiconductor structure 710 may be the above-mentioned Figures 1 to 4 The semiconductor structure 710 is, for example, a MOMA chip.

[0267] The semiconductor structure 710 may be mounted on the base 714 .

[0268] In some embodiments, the base 714 may be provided with a chip platform 712, a limit frame 711, and multiple (eg Figure 7 6) screw holes 716, washers 713 (as shown Figure 7 1 shown), fixing holes ( Figure 7 not shown), and two fastening surfaces 715.

[0269] Specifically, the chip platform 712 may be used to place the semiconductor structure 710 .

[0270] Limiting frame 711 : used to limit the position of the semiconductor structure 710 to ensure that the light beam enters and exits within the working area of ​​the semiconductor structure 710 .

[0271] The screw hole 716 can pass through the base 714. After the screw hole 716 of the sensor housing is aligned, the sensor base 714 is connected to the top shell 709 with a bolt 717 to form an integrated, sealed sensor housing to meet dust and water resistance requirements (for example, reaching the dust and water resistance level of IP68).

[0272] The sensor base 714 and the top shell 709 are squeezed against each other when fastened by the bolts 717 , which may cause the gasket 713 to deform, thereby filling the air gap between the base 714 and the top shell 709 , preventing dust and water from entering the sensor housing and contaminating the semiconductor structure 710 .

[0273] The fixing hole can be located at the center (axially) below the sensor base 714, and surrounded by multiple (such as Figure 7The semiconductor structure 710 is directly and rigidly connected to the object to be measured (or connected through an adapter plate) and fastened with bolts 717 so that the semiconductor structure 710 and the object to be measured are integrated. The purpose of the rigid connection is that the calculated sensor data can truly restore the vibration state of the object to be measured.

[0274] The bolt 717 corresponding to the screw hole 716 is as shown in FIG. Figure 7 The six bolts 717 shown are inserted through the screw holes 716 below the sensor base 714 and screwed to the bottom to close the sensor housing.

[0275] The fastening surface 715 can facilitate the use of tools such as a wrench or pliers to clamp, fix and / or screw the housing of the semiconductor structure 710 when installing the sensor.

[0276] The optical fiber 701 can be used to input a laser signal of a laser.

[0277] Specifically, the optical fiber 701 can be used as a carrier for transmitting the detection light and the feedback light. The optical fiber 701 can also be wrapped with an optical cable 702. In other words, the optical cable 702 can be wrapped outside the optical fiber 701.

[0278] The optical cable 702 can be used to protect the optical fiber 701 and prevent the optical fiber 701 from being stretched or / and squeezed by external forces, thereby preventing abnormal loss or even breakage.

[0279] The first end of the optical collimator 703 is coupled to the optical fiber 701 for collimating the received laser signal and transmitting it to the second end of the optical collimator 703 .

[0280] In some embodiments, the optical collimator 703 can be used for optical coupling between the optical fiber 701 and the semiconductor structure 710 , that is, the incident light beam enters the semiconductor structure 710 with as low light loss as possible, and the feedback light beam also enters the optical fiber 701 with low loss.

[0281] The end face of the optical collimator 703 has an anti-reflection (AR) film, so that the gap between the optical collimator 703 and the semiconductor structure 710 will not form an FP interference cavity, which is beneficial to the demodulation of the signal. The types of optical collimators 703 include focusing lenses, fiber lenses, self-focusing gradient-index lenses (G-lens), and spherical lenses (Conventional-lens, C-lens). Figure 7 The optical collimator 703 shown may also include a ferrule-type device, such as a fiber optic ceramic ferrule or a fiber optic metal ferrule.

[0282] If the coupling efficiency is not considered, the cut section of the optical fiber 701 can also achieve a certain coupling effect within a certain distance (the distance between the end face of the optical fiber 701 section and the semiconductor structure 710) because the cut surface is perpendicular to the axial direction of the fiber core.

[0283] It should be noted that, in another specific embodiment, an optical collimation jumper including the above-mentioned optical collimator 703 may also be used. Figure 7 It can be regarded that the complete jumper is not shown, and only one end of the jumper with the optical collimator 703 is shown. One end of the (optical fiber 701 ) jumper is a pluggable optical collimator connector, which is coupled to the semiconductor structure 710 .

[0284] The first component of the pluggable structure is pluggably coupled to the second end of the optical collimator 703, and the second component of the pluggable structure is coupled to the semiconductor structure 710, so that the laser signal output by the second end of the optical collimator 703 vertically enters the first surface of the optical cavity layer; the first component and the second component of the pluggable structure are pluggably connected.

[0285] In the embodiment of the present invention, by adopting a pluggable structure, the optical coupling packaging structure can be conveniently assembled to realize the collimated input of the laser signal input by the optical fiber 701 to the semiconductor structure 710 installed on the base 714. Compared with other assembly methods (such as direct coupling of the optical fiber 701 and the semiconductor structure 710 by welding), the solution of the embodiment of the present invention can reduce the difficulty of assembly while ensuring accuracy, and effectively control the assembly cost and manpower.

[0286] In such Figure 7 In the pluggable structure shown, the pluggable structure includes: a coaxial nut 706 and a top shell 709 .

[0287] Specifically, the first component of the pluggable structure may be one of the coaxial nut 706 and the top shell 709 , and the second component of the pluggable structure may be the other of the coaxial nut 706 and the top shell 709 .

[0288] The first end of the coaxial nut 706 is coupled to the second end of the optical collimator 703 .

[0289] The optical collimator 703 can be placed in the coaxial nut 706 and can be fixed with glue. The end face of the optical collimator 703 can be flush with the end of the coaxial nut 706 close to the semiconductor structure 710 (i.e., the end with threads) to ensure that the end face of the optical collimator 703 is not damaged.

[0290] Furthermore, the optical coupling package assembly may further include a crimping ring 704 , a first end of which is coupled to the optical cable 702 , and a second end of which is connected to a first end of the optical collimator 703 .

[0291] Specifically, the other end of the coaxial nut 706 may be an embossed end, which may be crimped with the crimping clamp 704 to the optical cable 702, so that the optical cable 702 is not pulled off by external force.

[0292] The crimping clamp 704 can cooperate with the embossed end of the coaxial nut 706 to crimp and tighten the optical cable 702.

[0293] Furthermore, the optical coupling package combination may further include a protective tail sleeve 705 .

[0294] The first end of the protective tail sleeve 705 is sleeved on the outside of the optical cable 702, which can be regarded as the optical cable 702 inserted into the hollow protective tail sleeve 705; the second end of the protective tail sleeve 705 is connected to the coaxial nut 706 or the first end of the FC / PC connector.

[0295] Specifically, a circle of raised steps in the middle of the coaxial nut 706 can be used to clamp the protective tail sleeve 705 .

[0296] The inner cross section of the protective tail sleeve 705 may have a circle of concave annular grooves, which are interlocked with a circle of raised steps of the coaxial nut 706, and are coated with glue to finally clamp the optical collimator 703.

[0297] The top shell 709 can be installed on the base 714, and has a hollow chamber for accommodating the semiconductor structure 710 between the top shell 709 and the base 714, and has a coaxial screw hole 707 adapted to the coaxial nut 706; wherein, the central axis direction of the connected coaxial nut 706 and the coaxial screw hole 707 is consistent with the direction of the laser signal output by the optical collimator 703.

[0298] Specifically, the coaxial screw hole 707 can be interconnected with the coaxial nut 706 of the optical collimation jumper, where a fine-pitch screw hole can be used so that the detection beam emitted from the optical fiber 701 can be better vertically emitted to the semiconductor structure 710, and the feedback beam can be vertically emitted from the semiconductor structure 710 and enter the interior of the optical fiber 701 through the optical collimator 703.

[0299] The axial center of the bottom of the sensor top shell 709 is recessed, so that the sensor base 714 chip platform 712 carrying the semiconductor structure 710 can be easily embedded into the top shell 709 and close to the coaxial screw hole 707; the bottom edge of the top shell 709 has screw holes 716 corresponding to the base 714, so as to facilitate the closing of the sensor housing.

[0300] In addition, the top of the top shell 709 may also be provided with a coaxial screw hole 707 and a recessed platform 708. The recessed platform 708 allows the protective tail sleeve 705 of the optical alignment jumper with the optical collimator 703 to sink into the housing of the sensor, thereby preventing dust and water from entering the interior of the sensor through the connection.

[0301] Reference Figure 8 , Figure 8 is a partial exploded view of another optical coupling package assembly in an embodiment of the present invention. Specifically, Figure 8 Another pluggable structure is shown.

[0302] The pluggable structure may include: a top shell 804 and an FC / PC connector 801 .

[0303] Specifically, the first component of the pluggable structure may be one of the FC / PC connector 801 and the top shell 804 , and the second component of the pluggable structure may be the other of the FC / PC connector 801 and the top shell 804 .

[0304] The first end of the FC / PC connector 801 is pluggably coupled to the second end of the optical collimator (not shown). Figure 7 An optical collimator 703 is shown.

[0305] The top shell 804 is mounted on the base (not shown) and has a hollow chamber for accommodating the semiconductor structure between the top shell 804 and the base. The top shell 804 has an FC / PC connector interface 802 adapted to the FC / PC connector 801. Figure 7 Base 714 is shown.

[0306] After the FC / PC connector 801 is connected to the FC / PC connector interface 802 through the through hole 803 , the transmission direction of the laser signal is consistent with the direction of the laser signal output by the optical collimator.

[0307] In some embodiments, the end face of the optical collimator has an anti-reflection (AR) film, so that the gap between the optical collimator and the semiconductor structure will not form an FP interference cavity, which is beneficial to the demodulation of the signal. The types of optical collimators include focusing lenses, fiber lenses, self-focusing gradient-index lenses (G-lens), and spherical lenses (Conventional-lens, C-lens). Figure 8 The optical collimator shown may also include a ferrule-type device, such as a fiber optic ceramic ferrule or a fiber optic metal ferrule.

[0308] It should be pointed out that although Figure 8 FC / PC is used as an example of an optical plug connector. In a specific implementation, other appropriate optical plug connectors, such as FC / angled physical contact (APC), Lucent connector (LC), Stab & Twist (ST), square connector (SC), etc., can also be used to connect to the demodulation device.

[0309] It should be noted that an FC / PC connector (the ceramic ferrule head of the modified universal connector is flat) can also be used to connect to the housing, so that the end face of the optical fiber section inserted into the ceramic ferrule of the FC / PC connector can be optically coupled with the semiconductor result.

[0310] The connection portion between the upper surface of the top shell of the semiconductor structure-based sensor (such as MOMA sensor) and the optical collimator can also be replaced by an optical interface of a universal optical connector such as FC / PC or FC / Ultra Physical Contact (UPC).

[0311] The base and top shell of the sensor based on semiconductor structure (such as MOMA sensor) are not fastened by bolts, but by threads. For example, the outer circle threads of the base and the inner circle threads of the top shell are screwed together to tighten and close.

[0312] It should be understood that the term "and / or" herein is merely an association relationship describing associated objects, indicating that three relationships may exist, for example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " herein indicates that the associated objects before and after are in an "or" relationship. As used herein, unless otherwise expressly stated, the term "or" covers all possible combinations unless not feasible. For example, if a component is stated to include A or B, then unless otherwise expressly stated or not feasible, the component may include A, or B, or A and B. As a second example, if a component is stated to include A, B, or C, then unless otherwise expressly stated or not feasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0313] The "plurality" appearing in the embodiments of the present application refers to two or more.

[0314] Relational terms appearing in the embodiments of the present application, such as first, second, etc., are only used to distinguish an entity or operation from another entity or operation, and do not require or imply any actual relationship or order between these entities or operations. In addition, the words "include", "have", "include" and other similar forms are intended to be equivalent in meaning and are open-ended, and one or more items following any of these words are not meant to be an exhaustive list of such one or more items, or to be limited to the listed one or more items.

[0315] It should be pointed out that the serial numbers of the steps in this embodiment do not limit the execution order of the steps.

[0316] In the foregoing description, embodiments have been described with reference to many specific details, which may vary depending on the implementation. Certain changes and modifications may be made to the described embodiments. In view of the description and practice of the present application disclosed herein, other embodiments will be clear to those skilled in the art. The description and examples are intended to be considered as merely exemplary, and the true scope and spirit of the present application are indicated by the following claims. The order of steps shown in the accompanying drawings is also intended to be used for illustrative purposes only and is not intended to be limited to any particular order of steps. Therefore, it will be appreciated by those skilled in the art that these steps may be performed in different orders while implementing the same method.

[0317] In the drawings and the specification, exemplary embodiments have been disclosed. However, many variations and modifications may be made to these embodiments. Therefore, although specific terms are employed, they are used only in a general and descriptive sense and not for the purpose of limitation.

[0318] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A semiconductor structure, characterized in that: include: An optical cavity layer, a laser signal enters from a first surface of the optical cavity layer, wherein a second surface of the optical cavity layer has a first reflective film; A resonance layer, wherein the first surface of the resonance layer faces the second surface of the optical cavity layer, wherein the resonance layer comprises: A mass block, wherein the mass block can vibrate in a direction perpendicular to the first surface of the resonance layer, and a second reflective film is provided on a surface of the mass block facing the second surface of the optical cavity layer, so that a first optical resonance cavity is formed between the first surface of the resonance layer and a surface of the mass block facing the second surface of the optical cavity layer; The laser signal forms a comb-shaped spectrum in the first optical resonant cavity, and the cavity length of the first optical resonant cavity is determined by a first frequency based on a minimum wavelength of the laser bandwidth and a second frequency based on a maximum wavelength of the laser bandwidth; The reflectivity of the first surface of the optical cavity layer is less than the reflectivity of the second surface of the optical cavity layer; a second optical resonant cavity is formed in the optical cavity layer material between the first surface of the optical cavity layer and the second surface of the optical cavity layer, the first optical resonant cavity is an air or vacuum resonant cavity, and the second optical resonant cavity is a silicon-based resonant cavity; the reflectivity of the first surface of the optical cavity layer is selected from [R th_2 , R th_3 ], where R th_2 Used to represent the second reflectivity threshold, R th_3 is used to represent the third reflectivity threshold, and R th_2 ≤R th_3 ≤R th_1 ; R th_1 is the first reflectivity threshold, the reflectivity of the first reflective film is greater than or equal to R th_1 , and / or, the second reflective film is greater than or equal to R th_1 .

2. The semiconductor structure according to claim 1, characterized in that: The cavity length of the first optical resonant cavity satisfies the following formula: ； in, It is used to represent the cavity length of the first optical resonant cavity, The first frequency used to represent the minimum wavelength based on the laser bandwidth, a second frequency for representing a maximum wavelength based on the bandwidth of the laser; c is used to represent the speed of light, λ min Minimum wavelength used to express the bandwidth of a laser, λ max Used to express the maximum wavelength of the laser bandwidth, Used to represent the refractive index coefficient of the first optical resonant cavity.

3. The semiconductor structure according to claim 1, characterized in that: The first surface of the optical cavity layer has a first anti-reflection film; The transmittance of the first anti-reflection film is greater than or equal to a first transmittance threshold.

4. The semiconductor structure according to claim 1, characterized in that: The material of the optical cavity layer is a silicon-based material, and the first surface of the optical cavity layer has no reflective film or anti-reflective film; Alternatively, the first surface of the optical cavity layer has a third reflective film, and the reflectivity of the third reflective film is [R th_2 , R th_3 ].

5. The semiconductor structure according to claim 1, characterized in that: The cavity length of the second optical resonant cavity satisfies the following formula: ； in, is used to represent the cavity length of the second optical resonant cavity, The first frequency used to represent the minimum wavelength based on the laser bandwidth, a second frequency for representing a maximum wavelength based on the bandwidth of the laser; c is used to represent the speed of light, λ min Minimum wavelength used to express the bandwidth of a laser, λ max Used to express the maximum wavelength of the laser bandwidth, is used to represent the refractive index coefficient of the second optical resonant cavity.

6. The semiconductor structure according to claim 1, characterized in that The resonance layer comprises: frame; A plurality of elastic connection components, wherein the plurality of elastic connection components are symmetrically connected to two inner sides of the frame; The mass block is suspended on the frame through the elastic connecting component and is surrounded by the frame; Wherein, the mass block can vibrate along a direction perpendicular to the first surface of the resonance layer under the drive of the elastic connection component.

7. The semiconductor structure according to claim 6, characterized in that: The plurality of elastic connecting components include at least two groups of elastic connecting components distributed in a mirror image; The mirror planes of the two groups of elastic connecting components are parallel to the plane where the frame is located.

8. The semiconductor structure according to claim 6 or 7, characterized in that: The elastic connecting component is in a curved or folded line shape and includes one or more of the following: The elastic connecting component is an I-shaped fold line; The elastic connecting component is in the form of a T-shaped fold line; The elastic connecting component is an S-shaped fold line; The elastic connecting component is a W-shaped fold line; The elastic connecting component is an L-shaped fold line; The elastic connecting component is an X-shaped fold line; The elastic connecting component is an M-shaped fold line; The elastic connecting component is a second structural block with a hollow structure.

9. The semiconductor structure according to claim 6, characterized in that: The frame, the plurality of elastic connection components and the mass block are an integrally formed structure formed by a semiconductor manufacturing process.

10. The semiconductor structure according to claim 1, characterized in that The second surface of the resonance layer has a second anti-reflection film; Wherein, the transmittance of the second anti-reflection film is greater than or equal to a second transmittance threshold.

11. The semiconductor structure according to claim 1, characterized in that: The second surface of the optical cavity layer has a first recessed portion, and the bottom surface of the first recessed portion is a plane; Wherein, the first reflective film is located on the bottom surface of the recessed portion; The projection of the mass block on the second surface of the optical cavity layer is within the bottom surface of the first recessed portion.

12. The semiconductor structure according to claim 1, characterized in that The semiconductor structure further comprises: A capping layer, wherein a first surface of the capping layer faces a second surface of the resonance layer; Wherein, the surface roughness of the first surface of the capping layer is greater than or equal to a first surface roughness threshold; or, The first surface and the second surface of the capping layer are both coated with a third anti-reflection film, wherein the transmittance of the third anti-reflection film is greater than or equal to a third transmittance threshold, and the first surface and the second surface of the capping layer are opposite to each other.

13. The semiconductor structure according to claim 12, characterized in that: The first surface of the capping layer has a second recessed portion, and the bottom surface of the second recessed portion is a plane; Wherein, the surface roughness of the bottom surface of the second recessed portion is greater than or equal to the first surface roughness threshold; The projection of the proof mass on the first surface of the capping layer is within the bottom surface of the second recessed portion.

14. The semiconductor structure according to claim 12, characterized in that: The semiconductor structure includes one or more of the following: The optical cavity layer and the resonance layer are connected by bonding; The distance between the second surface of the optical cavity layer and the first surface of the resonance layer is greater than or equal to the maximum displacement amplitude of the mass block; The resonance layer and the cover layer are connected by bonding; The optical cavity layer is formed based on a semiconductor substrate after double-sided polishing; The resonance layer is formed based on a semiconductor substrate after double-sided polishing; The capping layer is formed based on a semiconductor substrate that has been subjected to a single-side polishing process, and the first surface of the capping layer is a polishing surface.

15. An acceleration detection method of a semiconductor structure according to any one of claims 1 to 14, characterized in that: The mass block vibrates in a direction perpendicular to the first surface of the resonance layer; The method comprises: Determine the displacement amplitude of the mass block at time t , wherein the mass block vibrates in a direction perpendicular to the first surface of the resonant layer, and the displacement amplitude is It is used to express the difference between the position of the mass at time t and the position when it is in a stationary state; The acceleration of the mass block in a direction perpendicular to the first surface of the resonance layer is determined as: ;in, It is used to indicate the acceleration at the current temperature Temp. It is used to represent the spring constant of the mass block at the current temperature Temp. Used to indicate the mass of the mass block, It is used to represent the displacement amplitude of the mass block at the current temperature Temp at time t. Used to represent FP cavity The absolute cavity length at the current temperature Temp; And, determine the temperature at the time t : ;in, It is used to represent the linear expansion coefficient of the optical cavity layer material, is the initial temperature, is the distance between the first surface and the second surface of the optical cavity layer at the initial temperature T0, is the distance between the first surface and the second surface of the optical cavity layer at time t.

16. The method according to claim 15, characterized in that Determine the displacement amplitude of the mass block at time t ,include: Determine the distance between the first surface of the mass block and the second surface of the optical cavity layer when the mass block is in a stationary state ; The displacement amplitude of the mass block at time t is determined using the following formula: : ； ； in, It is used to represent the real-time cavity length of the first optical resonant cavity at time t, It is used to represent the peak-to-peak distance of adjacent interference peaks obtained after converting the spectrum obtained by the first optical resonator based on the laser bandwidth from the wavelength domain to the frequency domain, c is used to represent the speed of light, and n c1 Used to represent the refractive index coefficient of the first optical resonant cavity.

17. An optical coupling package assembly, characterized in that: include: The semiconductor structure according to any one of claims 1 to 14; a base, on which the semiconductor structure is mounted; An optical fiber, used for inputting a laser signal of a laser; the outer side of the optical fiber is wrapped with an optical cable; An optical collimator, a first end of which is coupled to the optical fiber and is used to collimate the received laser signal and output it to the second end of the optical collimator; A pluggable structure, wherein a first component of the pluggable structure is pluggably coupled to the second end of the optical collimator, and a second component of the pluggable structure is coupled to the semiconductor structure, so that a laser signal outputted from the second end of the optical collimator vertically enters the first surface of the optical cavity layer; The pluggable structure comprises: a coaxial nut, a first end of which is coupled to a second end of the optical collimator; a top shell, which is mounted on the base and has a hollow chamber for accommodating the semiconductor structure between the top shell and the base, and a coaxial screw hole adapted to the coaxial nut is provided on the top shell; wherein the central axis direction of the connected coaxial nut and the coaxial screw hole is consistent with the direction of the laser signal output by the optical collimator; A crimping clamp, a first end of which is coupled to the optical cable, and a second end of which is connected to the first end of the optical fiber collimator; The other end of the coaxial nut is an embossed end, which is crimped with the crimping clamp to the optical cable.

18. The optical coupling package assembly according to claim 16, wherein: Also includes: A protective tail sleeve, wherein a first end of the protective tail sleeve is sleeved on the outside of the optical cable, and a second end of the protective tail sleeve is connected to a first end of a coaxial nut or an FC / PC connector.

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