A precursor quality monitoring system and method based on non-contact acoustic viscosity sensing

Abstract

This invention discloses a precursor degradation monitoring system and method based on non-contact acoustic viscosity sensing. The system includes a gas cylinder body, an external acoustic sensor assembly, an acoustic impedance matching layer, a temperature sensor, and a control and calculation unit. The acoustic impedance matching layer is located between the sensor and the cylinder wall. The external acoustic sensor assembly emits high-frequency ultrasound and receives acoustic response signals. The control and calculation unit obtains the viscosity change of the liquid precursor inside the cylinder by performing inversion calculations on the acoustic response signals, and determines whether the precursor has deteriorated based on a closed-loop viscosity change analysis. This invention achieves fully external, non-destructive, and high-precision precursor viscosity inversion and degradation determination. Without requiring any openings or slots in the gas cylinder, the viscosity inversion error rate is controlled within ±2.0%, and a physical interlock is triggered upon confirmation of degradation. It is suitable for online quality monitoring of highly reactive liquid metal-organic precursors in semiconductor ALD / CVD processes.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing equipment and precursor delivery monitoring technology. Specifically, it relates to a precursor degradation monitoring system and method based on non-contact acoustic viscosity sensing. Background Technology

[0002] In advanced semiconductor manufacturing processes such as atomic layer deposition (ALD) and chemical vapor deposition (CVD), the deposition quality of metal thin films is highly dependent on the quality of the liquid precursor source. Precursors are often highly reactive organometallic compounds, which are prone to polymerization, decomposition, and other deterioration reactions under prolonged high-temperature baking or the intrusion of trace amounts of water and oxygen. This leads to an abnormally high viscosity, which in turn affects the uniformity, purity, and electrical properties of the deposited thin film.

[0003] In existing technologies, the main methods for monitoring precursor quality include the following: First, invasive electrical or mechanical probe detection, which requires the installation of sensors inside the cylinder. However, as high-pressure, high-purity containers, semiconductor special steel cylinders are susceptible to leakage and cross-contamination risks from any drilling, slotting, or introduction of foreign objects, compromising the inherent safety of the cylinder. Second, indirect estimation of precursor quality through pipeline flow rate is problematic due to its slow response and low accuracy, failing to reflect the true deterioration state of the precursor within the cylinder in real time and accurately. Third, existing non-contact ultrasonic measurement technologies often only perform simple "liquid level measurement," failing to detect the fundamental rheological changes within the liquid and thus unable to effectively determine precursor deterioration.

[0004] Therefore, existing technologies in the field of in-situ monitoring of precursor deterioration have the following core shortcomings: they cannot achieve accurate measurement of the viscosity of the liquid inside the cylinder without compromising the safety of the cylinder structure, nor can they promptly trigger physical interlock protection after deterioration is detected. There is an urgent need for a fully external, non-destructive, and high-precision in-situ monitoring solution for precursor deterioration. Summary of the Invention

[0005] To address the problems in related technologies, this invention proposes a precursor degradation monitoring system and method based on non-contact acoustic viscosity sensing. Without compromising the structural safety of special high-pressure or negative-pressure steel cylinders, it enables online degradation determination of liquid precursors containing a wide range of metal elements through externally attached acoustic viscosity inversion.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: A precursor degradation monitoring system based on non-contact acoustic viscosity sensing includes: A stainless steel cylinder body, wherein the cylinder body contains a liquid precursor. An external acoustic sensor assembly is attached to the smooth outer wall surface of the lower middle section of the cylinder body, and is used to emit high-frequency ultrasonic excitation signals and receive acoustic response signals after passing through the boundary between the cylinder wall and the precursor liquid. An acoustic impedance matching layer, located between the external acoustic sensor assembly and the outer surface of the cylinder body, is used to smoothly transition the acoustic impedance step between the transducer and the stainless steel cylinder wall. A temperature sensor is attached to the outer wall of the cylinder to acquire real-time temperature signals; The control and calculation unit is electrically connected to the external acoustic sensor assembly and the temperature sensor. It is used to obtain the viscosity change of the liquid precursor in the bottle by performing inversion calculation on the acoustic response signal, and to determine whether the liquid precursor has deteriorated based on the viscosity change closed loop.

[0007] As a preferred technical solution, the acoustic impedance of the acoustic impedance matching layer ranges from 10 MNayl to 25 MNayl, and its thickness is an odd multiple of one-quarter of the wavelength of ultrasonic waves propagating in the acoustic impedance matching layer.

[0008] As a preferred technical solution, the acoustic impedance matching layer is a flexible polymer composite material, the matrix of which is a heat-resistant epoxy resin or silicone rubber, and one or more of alumina, tungsten carbide, titanium dioxide or tungsten powder are doped into the matrix.

[0009] As a preferred technical solution, the acoustic impedance matching layer is a plastic soft metal material selected from indium foil, aluminum foil or lead foil, and its thickness is 0.05mm to 0.3mm.

[0010] As a preferred technical solution, the acoustic impedance matching layer is a rigid transition block structure, and its material is aluminum, magnesium or their alloy, and its thickness is an odd multiple of one-quarter of the wavelength of ultrasonic waves propagating in the transition block.

[0011] As a preferred technical solution, the liquid precursor is a liquid metal-organic precursor source or its organic solution containing one or more metal elements selected from cobalt (Co), ruthenium (Ru), aluminum (Al), molybdenum (Mo), copper (Cu), titanium (Ti), zirconium (Zr), hafnium (Hf), niobium (Nb) or tantalum (Ta).

[0012] As a preferred technical solution, the control calculation unit includes a temperature compensation unit, which is used to correct the temperature drift of the wall density, shear velocity, and precursor liquid density of the gas cylinder body based on the real-time temperature signal obtained by the temperature sensor.

[0013] As a preferred technical solution, the control calculation unit includes a boundary liquid level correction module, which is used to calculate the real-time liquid level based on the transit time of the liquid surface echo, and to compensate or remove the reflected signal when the liquid level is lower than the preset safety detection lower limit.

[0014] As a preferred technical solution, the control calculation unit includes a quality factor extraction and viscosity inversion module. The quality factor extraction and viscosity inversion module is used to extract the quality factor value of the acoustic resonance spectral line and its half-power bandwidth change, and substitute it into the acoustic-viscosity coupling dynamic equation to invert and calculate the real-time dynamic viscosity of the liquid precursor.

[0015] As a preferred technical solution, a pneumatic isolation valve is also included. The pneumatic isolation valve is installed on the precursor delivery pipeline of the gas cylinder and is electrically connected to the control and calculation unit. When the control and calculation unit determines that the precursor has deteriorated multiple times in a row, the control and calculation unit cuts off the control air source of the pneumatic isolation valve to achieve physical interlocking and locking of the pipeline.

[0016] This invention also provides a precursor degradation monitoring method based on non-contact acoustic viscosity sensing, comprising the following steps: Step 1: Use an external acoustic sensor assembly to emit sweeping sound waves onto the side wall of the gas cylinder to obtain the acoustic characteristic impedance and the velocimetric resonance line; Step 2: Use a temperature sensor to obtain the current temperature and call the temperature compensation unit to correct temperature drift; Step 3: Using the boundary liquid level correction algorithm, calculate the real-time liquid level based on the transit time of the liquid surface echo and the interface reflection coefficient. If the liquid level is lower than the safe detection limit, compensate or remove the reflected signal to eliminate the interference of gas-liquid interface changes on viscosity inversion. Step 4: By extracting the quality factor of the resonance spectral lines and the wall tangential shear attenuation coefficient, and substituting them into the acoustic-viscosity coupling dynamic equation, the real-time dynamic viscosity η of the liquid precursor is obtained. Step 5: Compare the obtained real-time dynamic viscosity η with the reference viscosity η0 at the same temperature. If the viscosity deviation exceeds the set threshold multiple times in a row, it is determined that the liquid precursor has deteriorated and an alarm is triggered to lock the closed loop.

[0017] As a preferred technical solution, the temperature drift correction in step two includes: correcting the wall density, shear velocity, and precursor liquid density of the cylinder body based on the real-time temperature.

[0018] As a preferred technical solution, the acoustic-viscosity coupling dynamic equation in step four is: ; Where, ρ wall c is the density of the stainless steel bottle wall.shear Let be the shear velocity of sound in stainless steel, n be the resonant harmonic order, ω be the angular frequency of the sound wave, and ρ be the real-time density of the liquid. This is the change in the reciprocal of the quality factor.

[0019] As a preferred technical solution, the change in the reciprocal of the quality factor Obtained through the following formula: ; Among them, Q loaded Q is the quality factor in the liquid state. empty R is the quality factor in the empty bottle state. L This represents the real part of the liquid shear acoustic impedance.

[0020] As a preferred technical solution, the "multiple times" in step five refers to three consecutive times; the set threshold is a viscosity deviation rate greater than or equal to 20%.

[0021] The present invention has the following beneficial effects: (1) The present invention uses an external acoustic sensor assembly to be non-destructively bonded to the outer wall of the cylinder through an acoustic impedance matching layer, without any opening, grooving or thinning of the cylinder wall, thus ensuring the inherent safety and zero pollution risk of the special high pressure and high purity container.

[0022] (2) By embedding an accurate theoretical model of acoustic-fluid shear boundary dynamics in the control calculation unit, the quality factor (Q value) attenuation change of the resonance spectrum of stainless steel bottle wall is extracted and substituted into the acoustic-viscosity coupling dynamic equation for closed-loop inversion solution. Experiments verify that the viscosity inversion error rate is strictly controlled within ±2.0%.

[0023] (3) By introducing an acoustic impedance matching layer with an acoustic impedance of 10MRayl to 25MRayl between the external acoustic sensor assembly and the cylinder wall, the overall energy transmittance is increased by more than 180% compared with the structure without matching layer, which effectively solves the problem of significant energy attenuation of ultrasound at the metal-liquid interface due to impedance mismatch.

[0024] (4) The temperature compensation unit corrects the material sound velocity and density in real time, and the boundary liquid level correction module eliminates the interference of gas-liquid interface changes on viscosity inversion, ensuring the robustness of inversion accuracy under complex working conditions.

[0025] (5) By setting the judgment logic of multiple consecutive exceeding the standard (such as three consecutive times), the misjudgment caused by single electrical test interference is prevented, and the pneumatic isolation valve is immediately cut off after the deterioration is confirmed to achieve physical interlocking and locking, thus realizing zero-delay hardware-level safety protection. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the precursor degradation monitoring system based on non-contact acoustic viscosity sensing according to the present invention.

[0028] Figure 2 This is a flowchart illustrating a method for monitoring precursor degradation based on non-contact acoustic viscosity sensing according to the present invention.

[0029] Among them: 101-Cylinder body, 102-External acoustic sensor assembly, 103-Acoustic impedance matching layer, 104-Temperature sensor, 105-Control and calculation unit, 1050-Central processing unit, 1051-Temperature compensation unit, 1052-Boundary liquid level correction module, 1053-Quality factor extraction and viscosity inversion module, 106-Pneumatic isolation valve, 107-Precursor liquid. Detailed Implementation

[0030] The technical solutions of the embodiments of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the invention, and not all embodiments. Based on the embodiments of the invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0031] In the description of this invention, it should be understood that the terms "opening", "upper", "lower", "top", "middle", "inner", etc., which indicate orientation or positional relationship, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the invention.

[0032] This invention provides a method and system for online degradation assessment and closed-loop interlocking control of liquid precursors containing a wide range of metallic elements (such as Co, Ru, Al, Mo, Cu, Ti, Zr, Hf, Nb, Ta, etc.) through externally bonded acoustic viscosity inversion, without compromising the structural safety of special high-pressure / negative-pressure steel cylinders. This system is particularly suitable for quality monitoring of highly reactive precursor sources in semiconductor atomic layer deposition (ALD) and chemical vapor deposition (CVD) processes.

[0033] Working principle (I) Overall working principle of the system The core working principle of this invention is as follows: An external acoustic sensor assembly is seamlessly attached to the outer wall of a straight-bottomed steel cylinder through an acoustic impedance matching layer, emitting high-frequency tangential shear sound waves towards the cylinder wall. When the sound waves penetrate the cylinder wall and reach the interface between the inner wall of the cylinder and the precursor liquid, the viscous damping of the liquid will consume some of the sound wave energy, causing the quality factor (Q value) of the shear resonance spectrum of the cylinder wall to decay. The control and calculation unit extracts the decay change of the Q value, performs temperature drift compensation by combining it with the real-time temperature collected by the temperature sensor, and then substitutes it into the acoustic-viscosity coupling dynamic equation to calculate the real-time dynamic viscosity η of the liquid precursor. η is compared with the reference viscosity η0. If the viscosity exceeds the set threshold multiple times consecutively, it is determined that the precursor has deteriorated, and the pneumatic isolation valve is triggered to achieve physical interlocking and locking. The entire process of this invention is external, non-contact, and does not damage any structural integrity of the steel cylinder.

[0034] (II) Principle of transmission optimization of acoustic impedance matching layer Sound waves are emitted from the transducer of an external acoustic sensor assembly into the stainless steel bottle wall and ultimately penetrate into the liquid precursor. Let the acoustic impedances of the transducer, matching layer, bottle wall, and precursor liquid be Z1, Z2, Z3, Z4, Z5, Z6, Z7, Z8, Z9, Z1, Z10, Z11, Z20, Z11, Z20, Z12, Z13, Z14, Z15, Z16, Z17, Z18, Z19, Z10, Z11, Z12, Z13, Z14, Z15, Z16, Z17, Z18, Z19, Z10 ... m When sound waves Z1, Z2, and Z3 are incident perpendicularly, the energy transmission coefficient T through the matching layer (whose thickness is designed to be an odd multiple of a quarter wavelength) can be expressed as: ; Where, k m Let d be the wave number. m To match the layer thickness.

[0035] When d m When = (2n+1)λ / 4, the resonant transmission coefficient simplifies to: .

[0036] To achieve perfect impedance matching (T) max If =1), then the ideal acoustic impedance value of the matching layer should satisfy... Since the transducer piezoelectric ceramic impedance Z1≈30 to 35 MNayl and the liquid precursor impedance Z3≈1.5 to 2.5 MNayl, the ideal matching impedance Z is calculated. m The impedance is approximately 6.7 to 9.3 MRayl. Considering the actual attenuation effect of the stainless steel bottle wall (Z2 ≈ 45 MRayl) sandwiched in the middle on sound velocity dispersion and standing wave, this invention uses multi-layer boundary condition analysis to lock the actual transition impedance of the matching layer between 10 MRayl and 25 MRayl. Within this range, the overall energy transmittance is improved by more than 180% compared to the structure without a matching layer.

[0037] (III) Acoustic shear wave attenuation and viscosity inversion principle When an external acoustic sensor generates a high-frequency shear wave and it is reflected at the interface between the inner wall of the cylinder and the precursor liquid, the viscous damping generated by the liquid causes the shear wave energy to dissipate into the liquid.

[0038] The dynamic viscosity η of the liquid precursor and the real part R of the shear acoustic impedance L The following relationship exists: ; Where ω = 2πf is the angular frequency of the sound wave. This represents the real-time density of the liquid.

[0039] The half-power bandwidth Δf (i.e., the bandwidth of the resonance spectral line) of the stainless steel bottle wall in shear mode is related to the total quality factor Q of the system, and the value of Q is defined as: ; Where f r This is the resonant center frequency.

[0040] The decrease in Q value due to viscous dissipation of the precursor (i.e., the change in the reciprocal of the quality factor Δ(1 / Q)) of the interfacial acoustic energy is expressed as: ; Where, ρ wall c is the density of the stainless steel bottle wall. shear denoted as the shear velocity in stainless steel, and n as the resonant harmonic order.

[0041] R L Substituting the formula into the above equation, we can derive the direct inversion closed-loop physical equation for the dynamic viscosity η: .

[0042] The above formula will now be further elaborated and explained: Define the quality factor of the resonant cavity

[0043] For an acoustic resonant cavity (here, mainly referring to a thickness of...), The quality factor of the steel cylinder container wall) Defined as:

[0044] in: This is the resonant angular frequency of the system; The maximum acoustic elastic kinetic energy stored within the resonant cavity of the gas cylinder wall; This refers to the sound power lost or consumed per unit time.

[0045] Written in reciprocal form, that is:

[0046] Calculate stored sound energy

[0047] Assuming the cylinder wall thickness is Its material density is The shear velocity is .exist Half-wave resonance (i.e.) Under the condition of ), the amplitude distribution of the shear wave inside the cylinder wall is a standing wave.

[0048] After integration, the total acoustic energy stored in a resonant cavity per unit area is:

[0049] in: This represents the vibration amplitude at the bottle wall interface.

[0050] Because resonance satisfies the relation Substituting it into the above formula, we get: ; Calculate the power loss of sound wave energy

[0051] When the system is not loaded with precursor liquid (no load), the sound wave energy is lost only through internal friction loss within the steel cylinder itself and a small amount of radiation loss to the outside air. We denote the lost sound power under no-load conditions as... .

[0052] When the cylinder is filled with precursor liquid (full load), sound wave energy will be transmitted through the interface between the cylinder inner wall and the precursor liquid.

[0053] Because the precursor fluid has viscous damping, it absorbs the energy of shear sound waves. The acoustic power (transmission loss) flowing per unit area into the fluid is determined by the following formula: in: The acoustic shear impedance of the liquid; It is the real part of its impedance; Therefore, the total power loss at full load is:

[0054] Calculate the difference term

[0055] Write the reciprocal formulas for internal friction under no-load and full-load conditions respectively: ; ; The difference between the two successfully eliminated the loss item of the empty bottle itself. : ; Substitution Complete the derivation The calculation in the second step Substitute the expression into the above formula: ; The simplified final expression is: .

[0056] The microprocessor in the control computing unit collects the half-power bandwidth variation of the resonance spectral line in real time, substitutes it into the physical equation, and eliminates the ρ and c caused by temperature changes. shear After drifting, the dynamic viscosity η is calculated directly by inversion.

[0057] Finally, η is compared with the reference viscosity η0. If the viscosity exceeds the set threshold multiple times, it is determined that the precursor has deteriorated, and the pneumatic isolation valve is triggered to achieve physical interlocking and locking. The entire process of this invention is external, non-contact, and does not damage any structural integrity of the cylinder.

[0058] Example 1 As attached Figure 1 As shown, the precursor degradation in-situ monitoring system in this embodiment includes the following core physical and signal circuit components: Cylinder body 101: Made of ultra-high purity 316L double-melted stainless steel, it contains precursor liquid 107 and is specifically designed for pressurized and vacuum environments. The cylinder body 101 has a straight cylindrical flat-bottom structure (i.e., flat bottom without a skirt / base design), which avoids acoustic interference and installation dead angles caused by welded skirts at the bottom of traditional stainless steel cylinders. The thickness of the bottom and walls is highly uniform to facilitate unobstructed attachment of acoustic components.

[0059] External acoustic sensor assembly 102: includes a piezoelectric transducer, which is closely attached to the outer wall of the cylinder body 101, for emitting high-frequency tangential shear sound waves to the cylinder wall and the precursor liquid inside the cylinder, and receiving acoustic response signals after passing through the boundary between the cylinder wall and the precursor liquid 107.

[0060] Acoustic impedance matching layer 103: It is tightly and physically bonded to the smooth outer wall surface of the lower middle section of the cylinder body 101, without intrusion or embedding into the cylinder wall, thus ensuring the inherent safety and zero contamination of this special high-purity pressure vessel. Its thickness, material, and acoustic impedance characteristics are optimized, with the acoustic impedance value locked between 10 MRayl and 25 MRayl, used to smoothly transition the acoustic impedance step between the transducer and the stainless steel cylinder wall. The thickness of the acoustic impedance matching layer 103 of this invention is designed to be an odd multiple of one-quarter of the wavelength of ultrasonic waves propagating in the matching layer material, so as to achieve maximum sound energy transmission by utilizing the quarter-wavelength impedance transformation effect.

[0061] To ensure that the acoustic impedance matching layer 103 maintains stable acoustic and physical properties under harsh semiconductor baking temperatures ranging from room temperature to 150°C, this invention provides the following three specific material implementation schemes: Option 1 employs a flexible polymer composite material, specifically using a heat-resistant epoxy resin (such as bisphenol A type high-temperature resistant epoxy resin) as the matrix, with a high proportion of submicron-sized heavy metal tungsten powder (W) and high-purity tungsten carbide (WC) powder uniformly doped into it. The epoxy resin accounts for 25% of the mass, while the tungsten powder and tungsten carbide powder account for 75%. After curing, this composite material is not prone to aging or deformation within a temperature range of 25℃ to 150℃. The measured sound velocity is 1980 m / s, the density is 7.6 g / cm³, and the calculated characteristic acoustic impedance is 15.0 MRayl, perfectly within the design range of 10 MRayl to 25 MRayl. In use, the 0.5 mm thick flexible polymer composite material is sandwiched between the piezoelectric transducer and the outer wall of the cylinder, with ultra-high temperature acoustic coupling silicone grease applied to both sides, and externally locked using stainless steel clamps.

[0062] Option 2 employs a plastic soft metal matching layer, specifically using high-purity indium foil (purity ≥99.99%) as an example. Indium possesses extremely low yield strength and excellent ductility. Under mechanical extrusion, the indium foil undergoes plastic rheology, completely filling the micron-level micro-unevenness between the piezoelectric transducer and the rough stainless steel bottle wall, thus eliminating the ultrasonic total reflection barrier caused by micro-air layers. The acoustic characteristic impedance of indium is 19.5 MNayl, within the design range. Generally, the thickness of the indium foil is selected as 0.1 mm. In use, the 0.1 mm pure indium foil is directly cut to the size of the piezoelectric transducer and placed between the piezoelectric transducer and the flat-bottomed steel bottle wall. A preload of greater than or equal to 5 MPa is applied through an external precision threaded clamp, causing the indium foil to undergo plastic adaptive deformation, forming a pure metal metallurgical-grade dry acoustic coupling interface free of microbubbles, with no risk of melting or aging at 150℃.

[0063] Option 3 employs a rigid transition block structure matching layer, specifically using a rigid acoustic transition block made of high-purity rust-resistant aluminum alloy (5A06 aluminum alloy) as an example. A high-frequency shear wave sensor with an operating frequency of f=2.5MHz is selected. The sound velocity of 5A06 aluminum alloy in shear wave mode is 3130m / s, and the shear wavelength at 2.5MHz is λ=1.252mm. The design thickness d of this matching layer is... m It is a quarter wavelength, i.e., d m=0.313mm. The acoustic impedance of 5A06 aluminum alloy is 14.5MRayl, its temperature resistance exceeds 300℃, and its physical and chemical properties are extremely stable. In use, the stainless steel side of the transition block is welded to the outer wall of the bottle using high-temperature lead-free eutectic solder or mechanically clamped under high pressure. The piezoelectric transducer is attached to the other side of the aluminum alloy transition block, achieving non-destructive external coupling with extremely high mechanical strength and sound transmission efficiency.

[0064] Temperature sensor 104: It is attached to the outer wall of the cylinder body 101 and is used to obtain the temperature of the outer wall of the cylinder body 101 in real time so that the control calculation unit 105 can perform real-time sound velocity and density temperature drift compensation.

[0065] Control and calculation unit 105: Electrically connected to the external acoustic sensor assembly 102 and temperature sensor 104 via a coaxial shielded cable. Control and calculation unit 105 includes a central processing unit 1050, a temperature compensation unit 1051, a boundary liquid level correction module 1052, and a quality factor extraction and viscosity inversion module 1053. The temperature compensation unit 1051 corrects the wall density, shear velocity, and precursor liquid density of the cylinder body 101 for temperature drift based on the real-time temperature signal acquired by the temperature sensor 104. The boundary liquid level correction module 1052 calculates the real-time liquid level based on the transit time of the liquid surface echo and compensates for or removes the reflected signal when the liquid level is below a preset safety detection limit. The quality factor extraction and viscosity inversion module 1053 extracts the quality factor value and half-power bandwidth change of the acoustic resonance spectral lines and substitutes them into the acoustic-viscosity coupling dynamics equation to invert and calculate the real-time dynamic viscosity of the liquid precursor.

[0066] Pneumatic isolation valve 106: Installed on the precursor delivery pipeline of the cylinder body 101 and electrically connected to the control calculation unit 105; When the control calculation unit 105 determines that the precursor has deteriorated multiple times in a row, the control calculation unit 105 cuts off the control air source of the pneumatic isolation valve 106 to realize the physical interlocking of the pipeline and prevent the deteriorated precursor from flowing to the wafer reaction chamber.

[0067] Example 2 Reference Figure 2 As shown, the specific steps of the monitoring algorithm executed by the control computing unit in this embodiment are as follows: Step 201: System initialization. Power on the system, read the classification of the precursor medium currently loaded in the stainless steel cylinder (e.g., TEMAH), and load the reference dynamic viscosity database η0(T) and the degradation deviation threshold coefficient (set to ±20% in this embodiment) for this type of cylinder.

[0068] Step 202: Signal Acquisition and Frequency Sweep. The control and computing unit controls the high-frequency pulse source to emit an ultrasonic frequency sweep excitation signal of 1MHz to 5MHz to the external acoustic sensor assembly. At the same time, the high-speed ADC acquires the reflected acoustic response signal at a sampling rate of not less than 100MSPS.

[0069] Step 203: Temperature Acquisition and Temperature Drift Compensation. The temperature sensor acquires the cylinder wall temperature T in real time. real The control calculation unit is based on T real Correcting the stainless steel wall density ρ in the formula wall (T), Stainless steel shear sound velocity c shear (T) and the real-time density ρ(T) of the precursor liquid.

[0070] Step 204: Interface level correction. To eliminate false interference caused by gas-liquid interface fluctuations or when the liquid in the cylinder is about to run out, the control calculation unit first reads the reflected sound wave from the bottom or side wall of the liquid surface and calculates its transit time (TOF) to obtain the current real-time liquid level H.

[0071] Step 205: Liquid Level Safety Assessment. Determine if H is greater than the set minimum safe liquid level height H. limit (e.g., 15mm). If the liquid level is below this level, proceed to step 206 for liquid level compensation or to issue a low liquid level warning; if the level is within the safe range, proceed directly to step 207 for viscosity inversion.

[0072] Step 207: Q-value and bandwidth extraction. Extract the shear resonance center frequency f of the cylinder sidewall from the reflected shear acoustic wave resonance spectrum. r And the corresponding -3dB half-power bandwidth Δf.

[0073] Step 208: Substitute into the formula to calculate the dynamic viscosity η. Calculate the current quality factor Q of the system based on the extracted Δf. loaded Compare the quality factor Q of the pre-stored empty bottle state. empty The change in quality factor Δ(1 / Q) is calculated. The temperature-compensated parameters are then substituted into the viscosity inversion formula. The real-time dynamic viscosity η of the current liquid precursor is calculated.

[0074] Step 209: Deviation Verification. Compare the real-time dynamic viscosity η with the temperature T. real The initial baseline healthy viscosity η0 is compared, and the deviation rate δ=|η-η0| / η0 is calculated.

[0075] Step 210: Closed-loop verification of three consecutive exceedances. Determine if δ is greater than the degradation deviation threshold (e.g., 20%). To prevent single-time misjudgment due to sudden electromagnetic interference, a continuous counter is set up internally. If the deviation is not exceeded, the counter is reset to zero, and the system returns to step 202 to continue loop monitoring; if the deviation exceeds the threshold, the counter N = N + 1.

[0076] Step 211: Trigger alarm and physical interlock. When counter N≥3 (i.e., three consecutive measurements exceed the limit), the control calculation unit completely determines that the precursor in the cylinder has undergone chemical deterioration. Immediately, the control air supply to the pneumatic isolation valve of the field delivery circuit is cut off via the I / O bus. The valve relies on its internal spring to reset, achieving forced physical locking, and sends an equipment lockout alarm to the ALD / CVD host, realizing hardware-level zero-delay physical interlock protection.

[0077] This invention addresses the long-term temperature compensation correction and the calibration of the classification reference viscosity η0 for ten representative liquid precursor sources containing different metal elements used in semiconductor manufacturing, as shown in Table 1 below: Table 1. Metamorphic characteristics and viscosity properties of typical precursors ; Comparison and verification To verify the monitoring accuracy of this invention, a straight-sided flat-bottomed steel cylinder with a low-yield-strength indium foil matching layer (0.1 mm thick) was used to load the CCTBA precursor in a simulated ALD reaction system, and an accelerated aging test was conducted at 75°C for 200 hours. The inverted viscosity measured by the system of this invention was compared with the actual viscosity measured by an invasive precision rheometer (sampling test, once every 24 hours), and the results are shown in Table 2 below: ; As can be seen from the above comparative data, the system of the present invention, with its non-invasive, fully externally integrated, non-destructive architecture, strictly controls the viscosity inversion error rate of liquid precursors within ±2.0%, which is highly consistent with the measured results of an invasive precision rheometer. The system can achieve precise physical interlocking cutoff within 3 hours (in this example, at the 147th hour, after three consecutive successful verifications) when the precursor deteriorates to the point of jeopardizing process safety (20% deviation), completely preventing unqualified precursors from entering the semiconductor reaction chamber.

[0078] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0079] The preferred embodiments of the invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A precursor degradation monitoring system based on non-contact acoustic viscosity sensing, characterized in that, include: A stainless steel cylinder body, wherein the cylinder body contains a liquid precursor. An external acoustic sensor assembly is attached to the smooth outer wall surface of the lower middle section of the cylinder body, and is used to emit high-frequency ultrasonic excitation signals and receive acoustic response signals after passing through the boundary between the cylinder wall and the precursor liquid. An acoustic impedance matching layer, located between the external acoustic sensor assembly and the outer surface of the cylinder body, is used to smoothly transition the acoustic impedance step between the transducer and the stainless steel cylinder wall. A temperature sensor is attached to the outer wall of the cylinder to acquire real-time temperature signals; The control and calculation unit is electrically connected to the external acoustic sensor assembly and the temperature sensor. It is used to obtain the viscosity change of the liquid precursor in the bottle by performing inversion calculation on the acoustic response signal, and to determine whether the liquid precursor has deteriorated based on the viscosity change closed loop.

2. The precursor degradation monitoring system based on non-contact acoustic viscosity sensing according to claim 1, characterized in that, The acoustic impedance of the acoustic impedance matching layer ranges from 10 MNayl to 25 MNayl, and its thickness is an odd multiple of one-quarter of the wavelength in which the ultrasonic wave propagates in the acoustic impedance matching layer.

3. The precursor degradation monitoring system based on non-contact acoustic viscosity sensing according to claim 2, characterized in that, The acoustic impedance matching layer is a flexible polymer composite material, the matrix of which is a heat-resistant epoxy resin or silicone rubber, and one or more of alumina, tungsten carbide, titanium dioxide or tungsten powder are doped into the matrix.

4. The precursor degradation monitoring system based on non-contact acoustic viscosity sensing according to claim 2, characterized in that, The acoustic impedance matching layer is a plastic soft metal material selected from indium foil, aluminum foil or lead foil, with a thickness of 0.05 mm to 0.3 mm.

5. The precursor degradation monitoring system based on non-contact acoustic viscosity sensing according to claim 2, characterized in that, The acoustic impedance matching layer is a rigid transition block structure, and its material is aluminum, magnesium or their alloy, with a thickness that is an odd multiple of one-quarter of the wavelength of ultrasonic waves propagating in the rigid transition block structure.

6. The precursor degradation monitoring system based on non-contact acoustic viscosity sensing according to claim 1, characterized in that, The liquid precursor is a liquid metal-organic precursor source or its organic solution containing one or more metallic elements selected from cobalt (Co), ruthenium (Ru), aluminum (Al), molybdenum (Mo), copper (Cu), titanium (Ti), zirconium (Zr), hafnium (Hf), niobium (Nb), or tantalum (Ta).

7. The precursor degradation monitoring system based on non-contact acoustic viscosity sensing according to claim 1, characterized in that, The control calculation unit includes a temperature compensation unit, which is used to correct the temperature drift of the wall density, shear velocity, and precursor liquid density of the gas cylinder body based on the real-time temperature signal obtained by the temperature sensor.

8. The precursor degradation monitoring system based on non-contact acoustic viscosity sensing according to claim 1, characterized in that, The control calculation unit includes a boundary liquid level correction module, which is used to calculate the real-time liquid level based on the transit time of the liquid surface echo, and to compensate or remove the reflected signal when the liquid level is lower than the preset safety detection lower limit.

9. The precursor degradation monitoring system based on non-contact acoustic viscosity sensing according to claim 1, characterized in that, The control calculation unit includes a quality factor extraction and viscosity inversion module. The quality factor extraction and viscosity inversion module is used to extract the quality factor value of the acoustic resonance spectral line and its half-power bandwidth change, and substitute it into the acoustic-viscosity coupling dynamic equation to invert and calculate the real-time dynamic viscosity of the liquid precursor.

10. The precursor degradation monitoring system based on non-contact acoustic viscosity sensing according to claim 1, characterized in that, It also includes a pneumatic isolation valve, which is installed on the precursor delivery pipeline of the gas cylinder and electrically connected to the control and calculation unit. When the control and calculation unit determines that the precursor has deteriorated multiple times in a row, the control and calculation unit cuts off the control air source of the pneumatic isolation valve to achieve physical interlocking and locking of the pipeline.

11. A method for monitoring precursor degradation based on non-contact acoustic viscosity sensing, characterized in that, Includes the following steps: Step 1: Use an external acoustic sensor assembly to emit sweeping sound waves onto the side wall of the gas cylinder to obtain the acoustic characteristic impedance and the velocimetric resonance line; Step 2: Use a temperature sensor to obtain the current temperature and call the temperature compensation unit to correct temperature drift; Step 3: Using the boundary liquid level correction algorithm, calculate the real-time liquid level based on the transit time of the liquid surface echo and the interface reflection coefficient. If the liquid level is lower than the safe detection limit, compensate or remove the reflected signal to eliminate the interference of gas-liquid interface changes on viscosity inversion. Step 4: By extracting the quality factor of the resonance spectral lines and the wall tangential shear attenuation coefficient, and substituting them into the acoustic-viscosity coupling dynamic equation, the real-time dynamic viscosity η of the liquid precursor is obtained. Step 5: Compare the obtained real-time dynamic viscosity η with the reference viscosity η0 at the same temperature. If the viscosity deviation exceeds the set threshold multiple times in a row, it is determined that the liquid precursor has deteriorated and an alarm is triggered to lock the closed loop.

12. The method according to claim 11, characterized in that, The temperature drift correction in step two includes: correcting the wall density, shear velocity, and precursor liquid density of the cylinder body based on the real-time temperature.

13. The method according to claim 11, characterized in that, The acoustic-viscosity coupling dynamic equation mentioned in step four is: ； Where, ρ wall c is the density of the stainless steel bottle wall. shear Let be the shear velocity of sound in stainless steel, n be the resonant harmonic order, ω be the angular frequency of the sound wave, and ρ be the real-time density of the liquid. This is the change in the reciprocal of the quality factor.

14. The method according to claim 13, characterized in that, The change in the reciprocal of the quality factor Obtained through the following formula: ； Among them, Q loaded Q is the quality factor in the liquid state. empty R is the quality factor in the empty bottle state. L This represents the real part of the liquid shear acoustic impedance.

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