Semiconductor process equipment and etching end point monitoring method

Abstract

The invention provides semiconductor process equipment and an etching end point monitoring method, relates to the technical field of semiconductor processing, and aims to solve the problem that an etching end point without glow discharge is difficult to monitor. The semiconductor process equipment comprises a process cavity, a laser emission device and a laser detection device, the process cavity is provided with a first side cavity wall and a second side cavity wall which are opposite, the first side cavity wall is provided with a first observation window, the second side cavity wall is provided with a second observation window, and the first observation window and the second observation window are correspondingly arranged; the laser emitting device is arranged outside the first observation window and comprises a first laser emitter and a second laser emitter, the emitting direction of the first laser emitter is horizontal, and the direction of the second laser emitter faces the wafer; the laser detection device is arranged outside the second observation window and comprises a first detector and a second detector, the first detector is used for receiving laser emitted by the first laser emitter, and the second detector is used for receiving laser emitted by the second laser emitter and reflected by the wafer. The method can effectively monitor the etching end point without glow discharge.

Description

Technical Field

[0001] This application relates to the field of semiconductor processing technology, and more specifically, to a semiconductor process equipment and an etching endpoint monitoring method. Background Technology

[0002] In advanced semiconductor manufacturing processes, a natural oxide layer (SiO2) with a thickness of approximately 0.5–2 nm inevitably forms on the surface of silicon (Si) wafers. x If this oxide layer is not completely and accurately removed, it will seriously affect the interface quality and device performance of subsequent critical processes such as atomic layer deposition (ALD), epitaxial growth, or metal contact.

[0003] Currently, the most widely used etching endpoint detection technology in industry is optical emission spectroscopy (OES). OES determines the etching endpoint by monitoring the intensity changes of characteristic emission lines of reaction byproducts (such as fluorine-silicon compounds, carbon oxides, etc.) during plasma glow discharge. However, this method is highly dependent on the plasma environment—a sufficiently strong spectral signal can only be generated when the gas is ionized and excited to a high energy state.

[0004] As advanced processes place increasing demands on interface damage control, plasma-free vapor phase etching technologies (such as thermal etch or radical etch) are gradually replacing traditional plasma processes due to their advantages of being gentle, highly selective, and free from charge damage. In these processes, the reaction is driven by neutral radicals generated by thermal energy or remote excitation, without producing glow discharge. Therefore, OES cannot detect effective emission signals and completely loses its endpoint monitoring capability.

[0005] Although attempts have been made to monitor changes in the concentration of gaseous byproducts using mass spectrometry (MS) or residual gas analysis (RGA), these methods only reflect the overall reaction rate and cannot directly characterize the breakage state of Si–O bonds or the integrity of Si terminations on the wafer surface. Furthermore, they are susceptible to interference from factors such as gas flow disturbances and adsorption on the chamber walls, leading to delayed endpoint determination or false triggering. In addition, while offline characterization methods (such as X-ray photoelectron spectroscopy and ellipsometry) offer high precision, they lack real-time capabilities and cannot be used for closed-loop control. Summary of the Invention

[0006] The first aspect of this application aims to provide a semiconductor process apparatus to solve the technical problem of difficulty in monitoring the etching endpoint in existing glow discharge-free processes.

[0007] The semiconductor process equipment provided in the first aspect of this application includes a process chamber, a laser emitting device, and a laser detection device. The process chamber has a first side cavity wall and a second side cavity wall opposite to each other. The first side cavity wall is provided with a first observation window, and the second side cavity wall is provided with a second observation window. The first observation window and the second observation window are correspondingly arranged. The laser emitting device is located outside the first observation window and includes a first laser emitter and a second laser emitter. The first laser emitter is positioned horizontally, and the second laser emitter is positioned towards the wafer in the process chamber. The laser detection device is disposed outside the second observation window and includes a first detector and a second detector. The first detector is used to receive the laser emitted by the first laser emitter, and the second detector is used to receive the laser emitted by the second laser emitter and reflected by the wafer.

[0008] The beneficial effects of the semiconductor process equipment in this application are: By setting corresponding first and second observation windows in the process chamber, lasers can be emitted by a first laser and a second laser outside the first observation window, respectively. The laser from the first laser, emitted horizontally, passes through the reactive gas above the wafer and is received by a first detector. By analyzing the laser received by the first detector, the condition of the reactive gas above the wafer can be obtained. Meanwhile, by emitting laser light onto the wafer using a second laser emitter and having it reflected, the condition of the wafer surface can be directly obtained by analyzing the reflected laser received by the second detector. This significantly improves the reliability, accuracy, and timeliness of monitoring the etching endpoint, which is beneficial for improving etching quality. Therefore, for non-glow etching reactions, this application can effectively monitor the endpoint of vapor phase etching.

[0009] In an optional technical solution, the first laser emitter includes a Raman laser emitter for emitting Raman laser signals; the first detector includes a Raman laser detector for detecting Raman laser signals.

[0010] In an optional technical solution, the first detector further includes a notch filter, a stray light filter, and a beam splitter arranged sequentially along the optical path, with the Raman laser detector located downstream of the beam splitter.

[0011] In an optional technical solution, the second laser emitter includes a pulsed laser emitter for emitting pulsed laser signals; the second detector includes a pulsed laser detector for detecting pulsed laser signals.

[0012] In an optional technical solution, the pulsed laser detector includes a PN photodiode or an avalanche photodiode for receiving pulsed laser signals.

[0013] In an optional technical solution, the semiconductor process equipment further includes a passive vibration isolation table, and the laser detection device is installed on the passive vibration isolation table.

[0014] In an optional technical solution, the semiconductor process equipment further includes an industrial control computer, and the first laser emitter, the second laser emitter, the first detector, and the second detector are all connected to the industrial control computer for signal transmission.

[0015] The second aspect of this application aims to provide a method for monitoring the etching endpoint, thereby solving the technical problem of the difficulty in monitoring the etching endpoint without glow discharge.

[0016] The etching endpoint monitoring method provided in the second aspect of this application, applied to the semiconductor process equipment of any of the above claims, includes: Determine that the wafer is located at a predetermined position within the process chamber; The laser intensity value is acquired in real time, and if at least one of the first laser intensity value and the second laser intensity value shows a sudden change in laser intensity signal, the etching endpoint is determined to have been reached. Wherein, the first laser intensity value is the laser intensity received by the first detector, and the second laser intensity value is the laser intensity received by the second detector; The laser intensity signal abrupt change includes: the first laser intensity value changing from a preset intensity range value to outside the preset intensity range value during the process; and / or, the second laser intensity value changing from an unstable fluctuation state to a stable state during the process.

[0017] The beneficial effects of the etching endpoint monitoring method in this application are: By collecting the laser intensity signal abrupt change of at least one of the first and second laser intensity values, the etching endpoint can be determined. This eliminates the need for glow discharge generated by the vapor phase etching reaction itself, allowing for timely monitoring of the etching endpoint even when the vapor phase etching reaction does not produce glow discharge. This enables timely interruption of the etching process, preventing damage to the underlying material and improving the quality of the etching reaction. Different changes in laser intensity values ​​are used as the signals for laser intensity abrupt changes.

[0018] In an optional technical solution, the first laser intensity value is the Raman signal intensity value of the laser received by the first detector: the first laser intensity value changes abruptly, including when the real-time Raman signal intensity is outside the first preset magnification range of the average Raman signal intensity, wherein the average Raman signal intensity is obtained from the real-time Raman signal intensity acquired during the etching step.

[0019] In an optional technical solution, the second laser intensity value is the reflected signal intensity value of the pulsed laser received by the second detector. The second laser intensity value remains stable, including a second preset multiple by which the real-time fluctuation value of the reflected signal is less than the cumulative fluctuation value of the reflected signal. The real-time fluctuation value of the reflected signal and the cumulative fluctuation value of the reflected signal are obtained from the real-time reflected signal intensity acquired during the etching step.

[0020] The third aspect of this application aims to provide a semiconductor process apparatus to solve the technical problem of difficulty in monitoring the etching endpoint without glow discharge.

[0021] The semiconductor process equipment provided in the third aspect of this application further includes an industrial control computer, which includes at least one processor and at least one memory, wherein the memory stores a computer program, and the computer program, when executed by the processor, implements the etching endpoint monitoring method of any of the above claims.

[0022] By installing an industrial control computer in the semiconductor process equipment capable of performing the above-described monitoring method, the semiconductor process equipment will have all the advantages of the above-described etching endpoint monitoring method, which will not be elaborated here. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments or background art of this application, the drawings used in the description of the embodiments or background art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of the semiconductor process equipment provided in Embodiment 1 of this application.

[0025] Figure 2 This is a schematic diagram of the structure of the laser detection device in the semiconductor process equipment provided in Embodiment 1 of this application.

[0026] Figure 3 This is a flowchart illustrating the etching endpoint monitoring method provided in Embodiment 2 of this application.

[0027] Figure 4 This is a schematic diagram of the curve showing the change of the first laser intensity over time in the etching endpoint monitoring method provided in Embodiment 2 of this application.

[0028] Figure 5 This is a schematic diagram of the change in reflected signal in the etching endpoint monitoring method provided in Embodiment 2 of this application.

[0029] Figure 6This is a schematic diagram of the curve showing the change of the second laser intensity over time in the etching endpoint monitoring method provided in Embodiment 2 of this application.

[0030] Figure 7 This is a flowchart illustrating the etching process steps using the etching endpoint monitoring method provided in Embodiment 2 of this application.

[0031] Explanation of reference numerals in the attached figures: 100 - Process chamber; 110 - First observation window; 120 - Base; 130 - Wafer; 140 - Oxide layer; 150 - Substrate; 200 - Laser emitting device; 210 - First laser emitter; 220 - Second laser emitter; 300-Laser detection device; 310-First detector; 311-Raman laser detector; 312-Notch filter; 313-Strray light filter; 314-Beam splitter grating; 320-Second detector; 330-Passive vibration isolation table; 410 - Industrial control computer; 420 - Monitor. Detailed Implementation

[0032] One related technology employs optical emission spectroscopy (OES) as a means of detecting the etching endpoint. Its working principle relies on exciting reactive gases and etching byproducts (such as fluorine-silicon compounds and carbon oxides) in a plasma glow discharge environment. By monitoring the intensity changes of characteristic emission lines at specific wavelengths in real time, it determines whether the native oxide layer has been completely removed. This method is typically integrated into capacitively coupled plasma (CCP) or inductively coupled plasma (ICP) etching equipment as part of a closed-loop control system.

[0033] This approach relies on plasma glow discharge: OES can only generate a detectable spectral signal when the gas is ionized and in an excited state, so it is not suitable for plasma-free processes, such as in glow-free, non-plasma environments like thermal etch or radical etch. Due to the lack of an excitation source, OES cannot acquire an effective signal, leading to the failure of the endpoint monitoring function; it cannot directly reflect the surface chemical state—even under plasma conditions, OES can only indirectly reflect changes in the concentration of gaseous byproducts and cannot directly detect Si–O bond breakage or the integrity of Si surface terminations; there is a risk of misjudgment and hysteresis: the signal is easily interfered with by factors such as chamber wall deposition and gas flow field disturbances, affecting the accuracy of endpoint judgment.

[0034] Related technology two employs a dry etching endpoint detection method based on component analysis. This method primarily relies on gas composition monitoring techniques at a single location (usually the entire vacuum chamber) (such as optical emission spectroscopy (OES) or mass spectrometry (MS)). It collects exhaust gases or reaction byproducts (such as SiF4, CO, CF) from the etching process. x By analyzing the concentration or intensity of a product (e.g., a product signal suddenly drops or another product signal suddenly rises) over time, the method identifies abrupt changes in specific signals to determine whether the film has been completely etched and triggers endpoint control. This method typically involves etching a known film structure under fixed process parameters to establish an empirical signal threshold or inflection point model for endpoint determination in subsequent similar processes.

[0035] However, this method is not sensitive to etching of ultrathin natural oxide layers or sub-nanometer films. Because the signal changes are weak and masked by background noise or upper / lower layer products, it is prone to under-etching or over-etching. It lacks spatial resolution of the etching dynamic process and cannot reflect the true chemical state of the etching front. The endpoint judgment is lagging and uncertain. Even if a state transition theory model is introduced for fitting, it still cannot fundamentally solve the problem of gaseous product mixing and is difficult to meet the high-precision endpoint detection requirements of advanced integrated circuit manufacturing.

[0036] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0037] Example 1: Figure 1 This is a schematic diagram of the semiconductor process equipment provided in Embodiment 1 of this application. Figure 1 As shown, the semiconductor process equipment provided in Embodiment 1 of this application includes a process chamber 100, a laser emitting device 200 and a laser detection device 300. The process chamber 100 has a first side cavity wall and a second side cavity wall opposite to each other. The first side cavity wall is provided with a first observation window 110 and the second side cavity wall is provided with a second observation window (not shown in the figure). The first observation window 110 and the second observation window are correspondingly arranged. The laser emitting device 200 is disposed outside the first observation window 110 and includes a first laser emitter 210 and a second laser emitter 220. The emission direction of the first laser emitter 210 is set horizontally, and the direction of the second laser emitter 220 is towards the wafer 130 in the process chamber 100. The laser detection device 300 is located outside the second observation window and includes a first detector 310 and a second detector 320. The first detector 310 is used to receive the laser emitted by the first laser emitter 210, and the second detector 320 is used to receive the laser emitted by the second laser emitter 220 and reflected by the wafer 130.

[0038] By setting corresponding first observation window 110 and second observation window in the process chamber 100, lasers can be emitted by a first laser and a second laser outside the first observation window 110, respectively. The laser from the first laser, which is emitted horizontally, passes through the reactive gas above the wafer 130 and is received by the first detector 310. The condition of the reactive gas above the wafer 130 can be obtained by analyzing the laser received by the first detector 310. Meanwhile, a laser is emitted towards the wafer 130 by the second laser emitter 220 and reflected. The surface condition of the wafer 130 can be directly obtained by analyzing the reflected laser received by the second detector 320. This significantly improves the reliability, accuracy, and timeliness of etching endpoint monitoring, which is beneficial for improving etching quality. Therefore, for non-glow etching reactions, this application can effectively monitor the endpoint of vapor phase etching.

[0039] In this embodiment, the first side cavity wall and the second side cavity wall are opposite each other. It is not strictly limited that the horizontal cross-section of the process chamber 100 is rectangular or square. The first side cavity wall and the second side cavity wall are cavity walls located at two parallel edges of a rectangle or square. Even if the process chamber 100 is circular, as long as the two cavity walls at both ends of the diameter direction are the opposite first side cavity wall and second side cavity wall, they can be the opposite first side cavity wall and second side cavity wall.

[0040] The corresponding arrangement of the first observation window 110 and the second observation window does not imply that they must be strictly aligned along the diameter of the process chamber 100 or the length of a certain side of the process chamber 100, without any difference whatsoever. The only requirement is that the laser light emitted by the first laser emitter 210 and the second laser emitter 220 through the first observation window 110 is ultimately received by the first and second observers. The first and second observation windows can be circular, with a diameter of 3cm to 6cm.

[0041] Figure 2 This is a schematic diagram of the structure of a laser detection device in a semiconductor process apparatus provided in Embodiment 1 of this application. Figure 2 As shown, optionally, the first laser emitter 210 includes a Raman laser emitter for emitting Raman laser signals; the first detector 310 includes a Raman laser detector 311 for detecting Raman laser signals.

[0042] Raman laser signals are emitted by the Raman laser emitter of the first laser emitter 210 and received by the Raman laser detector 311 of the first detector 310. During the etching process, the Raman laser signals will exhibit a Raman frequency shift after passing through the molecular clusters above the wafer 130. The Raman laser signals with the Raman frequency shift are received by the first detector 310 and then the signal is analyzed to obtain the Raman signal intensity.

[0043] Specifically, in this embodiment, the Raman laser emitter can be a conventional continuous wave laser placed horizontally, with a wavelength of 532nm or 980nm. Alternatively, an infrared laser with a wavelength ≥1μm can be selected. The power of the Raman laser emitter is 0.5mW~10mW, and the spot size is 50μm~200μm.

[0044] like Figure 2 As shown, optionally, the first detector 310 further includes a notch filter 312, a stray light filter 313 and a beam splitter 314 arranged sequentially along the optical path direction, and the Raman laser detector 311 is located downstream of the beam splitter 314.

[0045] The notch filter 312 can block the main laser peak and Rayleigh scattering signal; the stray light filter 313 can eliminate residual stray light; and the beam splitter grating 314 can separate the mixed optical signal according to wavelength in the transmission Raman circuit.

[0046] like Figure 1 and Figure 2 As shown, optionally, the second laser emitter 220 includes a pulsed laser emitter for emitting pulsed laser signals; and the second detector 320 includes a pulsed laser detector for detecting pulsed laser signals.

[0047] By emitting pulsed laser signals using a pulsed laser emitter, changes in the intensity of the reflected laser signal can occur when the material film at the laser spot location changes. This change in reflected light intensity can be used as the etching endpoint signal. Furthermore, pulsed lasers can be used to activate molecules, amplifying their vibrational states. When the concentration of the process gas is low, pulsed laser excitation can enhance the Raman laser signal, which is beneficial for obtaining the endpoint signal.

[0048] Specifically, if the surface layer to be etched is an oxide layer 140, the pulsed laser beam is reflected on the surface of the oxide layer 140 thin film, resulting in strong reflected light and a strong signal. However, once the oxide layer 140 thin film etching is complete, the silicon-based substrate 150 strongly absorbs the laser beam, significantly reducing or even eliminating the reflected light.

[0049] The pulsed laser emitter is tilted towards the wafer 130. The specific type of laser can be a nanolaser, picosecond laser, or femtosecond laser, with a wavelength of 350nm~460nm, a power of 2mW~20mW, and a spot size of 30μm~100μm. Because different materials have different reflectivities and absorptivities for laser light, the intensity of the reflected light signal from the pulsed laser varies significantly; nanoscale pulses are sufficient to meet the temporal resolution requirements of this signal variation.

[0050] Optionally, the pulsed laser detector includes a PN photodiode or an avalanche photodiode for receiving pulsed laser signals.

[0051] Because the intensity of the reflected signal of the pulsed laser varies due to the different types of materials, there is no need for filtering. The above types of diodes can be used to receive the pulsed laser and monitor the changes in light intensity.

[0052] like Figure 1 As shown, optionally, the semiconductor process equipment also includes a passive vibration isolation stage 330, on which the laser detection device 300 is mounted.

[0053] By setting up a passive vibration isolation table 330 to install the laser detection device 300, the vibration of the laser detection device 300 can be reduced to ensure the accuracy of signal reception.

[0054] Specifically, the laser detection device 300 is connected to the passive vibration isolation platform 330 at the bottom via a bracket.

[0055] like Figure 1 As shown, optionally, the semiconductor process equipment also includes an industrial control computer 410. The first laser emitter 210, the second laser emitter 220, the first detector 310 and the second detector 320 are all connected to the industrial control computer 410 for signal transmission.

[0056] An industrial control computer 410 controls the first laser emitter 210 and the second laser emitter 220, and receives signals from the first detector 310 and the second detector 320. It can accurately and timely process relevant signals and finally provide feedback on the endpoint of vapor phase etching.

[0057] In addition, in this embodiment, the industrial control computer 410 is also connected to the display 420, which can display the signal in real time on the display 420 to facilitate monitoring by the operator.

[0058] Example 2: Figure 3 This is a schematic flowchart of the etching endpoint monitoring method provided in Embodiment 2 of this application. Figure 3As shown, the etching endpoint monitoring method provided in Embodiment 2 of this application is applied to the semiconductor process equipment described above. The method includes the following steps: S302, confirm that the wafer 130 is located at a preset position in the process chamber 100; S304, real-time acquisition of at least one of the first laser intensity value and the second laser intensity value; if a sudden change in the laser intensity signal occurs in at least one of the first laser intensity value and the second laser intensity value, then the etching endpoint is determined to have been reached. The laser intensity signal abrupt change includes: the first laser intensity value changing from a preset intensity range value to outside the preset intensity range value during the process; and / or, the second laser intensity value changing from an unstable fluctuation state to a stable state during the process.

[0059] By collecting the laser intensity signal abrupt change of at least one of the first and second laser intensity values, the etching endpoint can be determined. This eliminates the need for glow discharge generated by the vapor phase etching reaction itself, allowing for timely monitoring of the etching endpoint even when the vapor phase etching reaction does not produce glow discharge. This enables timely interruption of the etching process, preventing damage to the underlying material and improving the quality of the etching reaction. Different changes in laser intensity values ​​are used as the signals for laser intensity abrupt changes.

[0060] In this embodiment, both the first and second laser intensity values ​​undergo abrupt changes to determine the etching endpoint. However, those skilled in the art should understand that determining a change in laser intensity signal and achieving the purpose of this invention can also be achieved by judging a change in either the first or second laser intensity value. Using a combination of both is simply more advantageous.

[0061] Figure 4 This is a schematic diagram showing the change of the first laser intensity over time in the etching endpoint monitoring method provided in Embodiment 2 of this application. Figure 4 As shown, optionally, the first laser intensity value is the Raman signal intensity value of the laser received by the first detector 310: the first laser intensity value has a sudden change, including the real-time Raman signal intensity being outside the first preset magnification range of the average Raman signal intensity, the average Raman signal intensity being obtained from the real-time Raman signal intensity obtained during the etching step.

[0062] During the etching reaction, the etching gas continuously reacts with the wafer 130, while simultaneously being continuously replenished into the process chamber 100, and the etching gas products are continuously removed. Therefore, the gas above the wafer 130 reaches a dynamic equilibrium. When the etching reaches its endpoint, the etching gas continues to be replenished, while the etching gas products have been removed, resulting in a new equilibrium of gas composition above the wafer 130, dominated by the introduced process gas. In other words, the gas composition above the wafer 130 changes compared to the etching process. Consequently, the intensity of the Raman active peak of the Raman signal changes. Therefore, by monitoring the Raman signal intensity value received by the first detector 310, the change in gas composition above the wafer 130 can be obtained, thus determining whether the etching has reached its endpoint.

[0063] In this embodiment, before the process gas is introduced, the first laser emitter 210 and the first detector 310 are turned on. The optical path of the first laser emitter 210 is located 0.5mm to 20mm above the wafer 130, and the first detector 310 collects the background signal. After the process begins, the reactive gas is introduced, and then the real-time Raman signal intensity is collected. The average Raman signal intensity is obtained based on the real-time Raman signal intensity. For example, if the process gas is introduced into the process chamber 100 starting from the 10th second after the start of timing, the average Raman signal intensity up to the 20th second is the average of the Raman signal intensity over a 10-second period from the 10th to the 20th second. The average Raman signal intensity at the 40th second is the average of the Raman signal intensity over a 30-second period from the 10th to the 40th second, and so on.

[0064] In this embodiment, the first preset magnification range can be 0.8 to 1.2 times. That is, when the real-time Raman signal intensity is greater than 1.2 times the average Raman signal intensity, or less than 0.8 times the average Raman signal intensity, a sudden change in the first laser intensity value is considered to have occurred. Figure 4 Taking the curve shown as an example, although the real-time Raman signal intensity began to rise from the 120s, and the average Raman signal intensity also rose accordingly, the rate of increase of the average Raman signal intensity was slow because it was the average value after the reaction gas was introduced. When the time reached the 130s, the real-time Raman signal intensity was greater than 1.2 times the average Raman signal intensity, which was considered to be the end of the etching process.

[0065] Figure 5 This is a schematic diagram of the change in reflected signal in the etching endpoint monitoring method provided in Embodiment 2 of this application. Figure 6 This is a schematic diagram showing the change in the intensity of the second laser over time in the etching endpoint monitoring method provided in Embodiment 2 of this application. Figure 5 and Figure 6As shown, optionally, the second laser intensity value is the reflected signal intensity value of the pulsed laser received by the second detector 320. The second laser intensity value remains stable, including a second preset multiple of the real-time fluctuation value of the reflected signal being less than the cumulative fluctuation value of the reflected signal. The real-time fluctuation value of the reflected signal and the cumulative fluctuation value of the reflected signal are obtained from the real-time reflected signal intensity acquired during the etching step.

[0066] As the etching reaction continues, the thickness of the etched material on the surface gradually decreases until it disappears completely. Therefore, the intensity of the reflected pulsed laser changes with the variation in the reflective material and its thickness. After the etched material is completely etched, the pulsed laser is reflected from the silicon substrate 150 into the second detector 320. The intensity value of the reflected pulsed laser signal received by the second detector 320 tends to stabilize. Therefore, the stability of the pulse signal intensity value can be used to confirm whether the etching endpoint has been reached.

[0067] Furthermore, especially in the mode of monitoring Raman signal intensity, since the Raman signal is relatively weak, it can be activated by pulsed laser to increase lattice vibration, which may introduce signal drift. Pulsed laser is emitted to monitor the reflectivity of the surface film during etching by monitoring a second laser intensity value. However, the accuracy of the pulsed laser signal is slightly lacking, so it can be used as an auxiliary to Raman signal intensity monitoring to determine the etching endpoint.

[0068] Among them, with Figure 6 For example, in the graph, the horizontal axis represents time, while the vertical axis represents the difference between the intensity of the reflected signal and the intensity of the emitted signal of the pulsed laser. The higher the vertical axis, the greater the difference between the reflected and emitted signal intensities, meaning the weaker the reflection of the pulsed laser. As can be seen from the graph, the signal fluctuates significantly starting from the 34th second of the timing, stabilizing after the 100th second. Therefore, the etching termination time can be determined as the 100th second.

[0069] The real-time fluctuation value of the reflected signal can be the mean square error of the real-time reflected signal intensity fluctuation over a period of time. Further, this period can be 5 seconds. For example, the real-time reflected signal fluctuation value at 40 seconds can be the mean square error from 35 seconds to 40 seconds; similarly, the real-time reflected signal fluctuation value at 90 seconds can be the mean square error from 85 seconds to 90 seconds, and so on. The cumulative fluctuation value of the reflected signal is the mean square error of the real-time reflected signal intensity from the start of the process gas introduction to the current moment. For example, if the process gas is introduced from 30 seconds, then the cumulative fluctuation value of the reflected signal at 50 seconds is the mean square error of the real-time reflected signal intensity from 30 seconds to 50 seconds, and the cumulative fluctuation value of the reflected signal at 90 seconds is the mean square error of the real-time reflected signal intensity from 40 seconds to 90 seconds.

[0070] The second preset magnification, for example, can be 0.3 times. This means that if the mean square error over a past period at a certain moment is less than 0.3 times the mean square error of the accumulated fluctuations, the intensity of the reflected pulsed laser signal received by the second detector 320 can be considered stable. This is because absolute stability is impossible due to limitations in measurement accuracy and equipment; fluctuations are inevitable. However, when the fluctuation range is small, the reflected signal intensity value can be considered stable, meaning the second laser intensity value remains stable.

[0071] The specific process using the monitoring method provided in this embodiment is as follows: The etching process can employ either thermally driven etching or free radical etching. In thermally driven etching, the process gases are NH3 + HF + He, with NH3 flow rates of 20 sccm ~ 100 sccm, HF flow rates of 5 sccm ~ 20 sccm, and He flow rates of 100 sccm ~ 1000 sccm. The ratio of these three gases must satisfy a ratio of 1:1:10 to 5:1:50. The process temperature is 25℃ ~ 200 °C, and the process pressure is 1 Torr ~ 10 Torr. Under the catalytic drive of temperature and NH3, HF reacts with SiO to generate SiF4 volatile products. He mainly serves as a heat conductor and diluent, resulting in good thermal uniformity while preventing excessively rapid etching.

[0072] In free radical etching, a remote plasma source with a power of 10 W to 50 W can be used to filter out charged particles such as electrons and ions through a filter grid to obtain free radicals. In this scheme, the proportion of He is higher than that in thermally driven etching, and the three gases meet the ratio of 1:2:10 to 3:1:100. This is because free radicals are more chemically active and have higher initial energy, so more He is needed to dilute the free radical concentration, reduce the free radical energy through inelastic collisions, and avoid excessively fast etching rate or plasma damage.

[0073] Both etching schemes have etching rates of 0.2 nm / s to 1 nm / s. During the etching process, there is no glow discharge in the reaction chamber, making it difficult to collect the endpoint signal using conventional OES.

[0074] Before the gas is introduced, the first laser emitter 210 and the second laser emitter 220 emit light. The continuous wave laser of the first laser emitter 210 forms a penetrating Raman optical path. The laser optical path is located 0.5 mm to 20 mm above the wafer 130. At this time, the background signal is collected.

[0075] Then, a reactive gas is introduced. At this point, the laser can be used to selectively excite the vibrational states of HF, NH3, or NF3 molecules, monitoring changes in the gas composition within the chamber. When the silicon oxide layer is etched and the dielectric layer is reached, the molecular weights of HF, NH3, or NF3 decrease or increase, resulting in changes in the Raman signal intensity, thus achieving endpoint detection. For example, the 905 cm⁻¹ of SiF₄... -1 Peak intensity change, NH4F at 1430cm -1 The changes in peak intensity are all characteristic changes in the intensity of Raman active peaks. When a change in Raman peak intensity occurs... Figure 4 When the signal strength increases significantly, the etching endpoint can be considered reached. The industrial control computer 410 outputs an endpoint signal to terminate the etching process.

[0076] Furthermore, short-wavelength pulsed lasers with wavelengths between 200 nm and 440 nm can be used to activate molecules and amplify their vibrational states. When the process gas concentration is low, pulsed laser excitation can enhance the transmitted Raman signal, which is beneficial for capturing the endpoint signal. The pulsed laser emitted by the second laser emitter 220 can also form a reflected light path. When the material film at the laser spot position changes, the intensity of the reflected laser signal changes, i.e., the intensity value of the second laser changes abruptly, which can be used as the etching endpoint signal. No filtering is required for the reflected signal; only the intensity change of the main optical path needs to be monitored. Figure 5 As shown, the short-wavelength light beam is reflected on the surface of the oxide layer 140 thin film. The reflected light is strong and the reflected signal is strong. When the oxide layer 140 thin film is completely etched, the Si-based substrate 150 absorbs more short-wavelength photons, and the reflected light is significantly weakened or even disappears. Therefore, the intensity of the reflected light signal, i.e., the intensity value of the second laser, is significantly reduced.

[0077] After wafer 130 enters the process chamber 100, two laser beams are emitted: a Raman laser from the first laser emitter 210 and a pulsed laser from the second laser emitter 220. The substrate 120 holds wafer 130 and introduces etching gas or free radicals. During etching, the etching endpoint is monitored by tracking both the Raman laser signal and the reflected pulsed laser signal. Since the Raman laser signal may be weak, pulsed laser activation is needed to increase lattice vibration, which may cause Raman laser signal drift. Therefore, pulsed laser emission and reception are used to monitor the surface film reflectivity. However, the emission signal has low accuracy and is affected by the aperture ratio, serving as an auxiliary indicator for Raman signal endpoint determination. Based on the two laser signals, the final etching endpoint is output, primarily using the Raman signal, with the reflected signal assisting in endpoint determination. The signal is then processed and archived by the logic storage section of the industrial control computer 410, and can also be used for learning and training.

[0078] The following process is based on an etching endpoint monitoring method that monitors both the first laser intensity value and the second laser intensity value. However, those skilled in the art should understand that the etching endpoint monitoring method provided in this application can also monitor only the first laser intensity value, i.e., the Raman signal, or only the second laser intensity value, i.e., the reflection signal.

[0079] Figure 7 This is a schematic flowchart illustrating the etching process steps using the etching endpoint monitoring method provided in Embodiment 2 of this application. Figure 7 As shown, in summary, the process steps using this etching endpoint monitoring method include: S402, transfer wafer 130 into process chamber 100.

[0080] S404, the first laser emitter 210 emits Raman laser, and the second laser emitter 220 emits pulsed laser.

[0081] S406. Introduce process gas into process chamber 100 to perform thermally driven etching or free radical etching.

[0082] S408, monitor the Raman signal received by the first detector 310 and the reflected signal received by the second detector 320.

[0083] S410. If the first laser intensity value changes abruptly, i.e. the Raman signal exceeds the preset intensity range, and the second laser intensity value changes from a fluctuating state to a stable state, i.e. the reflected signal is stable.

[0084] S412, outputs the etching endpoint signal.

[0085] S414, Etching terminated.

[0086] Example 3: The semiconductor process equipment provided in Embodiment 3 of this application further includes an industrial control computer, which includes at least one processor and at least one memory. The memory stores a computer program, and when the computer program is executed by the processor, it implements the etching endpoint monitoring method described above.

[0087] By installing an industrial control computer in the semiconductor process equipment capable of performing the above-described monitoring method, the semiconductor process equipment will have all the advantages of the above-described etching endpoint monitoring method, which will not be elaborated here.

[0088] While this application discloses the above information, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of this application; therefore, the scope of protection of this application shall be determined by the scope defined in the claims.

[0089] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the term "comprising" or any other variations thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0090] In the above embodiments, descriptions of directions such as "up" and "down" are based on the accompanying drawings.

[0091] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application.

[0092] Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A semiconductor process apparatus, characterized in that, It includes a process chamber (100), a laser emitting device (200) and a laser detection device (300). The process chamber (100) has a first side cavity wall and a second side cavity wall opposite to each other. The first side cavity wall is provided with a first observation window (110) and the second side cavity wall is provided with a second observation window. The first observation window (110) and the second observation window are provided correspondingly. The laser emitting device (200) is disposed outside the first observation window (110) and includes a first laser emitter (210) and a second laser emitter (220). The emission direction of the first laser emitter (210) is set horizontally, and the direction of the second laser emitter (220) is toward the wafer (130) in the process chamber (100). The laser detection device (300) is disposed outside the second observation window and includes a first detector (310) and a second detector (320). The first detector (310) is used to receive the laser emitted by the first laser emitter (210), and the second detector (320) is used to receive the laser emitted by the second laser emitter (220) and reflected by the wafer (130).

2. The semiconductor process equipment according to claim 1, characterized in that, The first laser emitter (210) includes a Raman laser emitter for emitting Raman laser signals; the first detector (310) includes a Raman laser detector (311) for detecting Raman laser signals.

3. The semiconductor process equipment according to claim 2, characterized in that, The first detector (310) further includes a notch filter (312), a stray light filter (313) and a beam splitter (314) arranged sequentially along the optical path direction, and the Raman laser detector (311) is located downstream of the beam splitter (314).

4. The semiconductor process equipment according to any one of claims 1-3, characterized in that, The second laser emitter (220) includes a pulsed laser emitter for emitting pulsed laser signals; the second detector (320) includes a pulsed laser detector for detecting pulsed laser signals.

5. The semiconductor process equipment according to claim 4, characterized in that, The pulsed laser detector includes a PN photodiode or an avalanche photodiode for receiving pulsed laser signals.

6. The semiconductor process equipment according to claim 4, characterized in that, The semiconductor process equipment also includes a passive vibration isolation table (330), and the laser detection device (300) is installed on the passive vibration isolation table (330).

7. The semiconductor process equipment according to claim 4, characterized in that, The semiconductor process equipment also includes an industrial control computer (410), and the first laser emitter (210), the second laser emitter (220), the first detector (310) and the second detector (320) are all connected to the industrial control computer (410) for signal transmission.

8. A method for monitoring the etching endpoint, characterized in that, Applied to the semiconductor process equipment according to any one of claims 1-7, the method comprises: Determine that the wafer (130) is located at a preset position in the process chamber (100); The laser intensity value is acquired in real time, and if at least one of the first laser intensity value and the second laser intensity value shows a sudden change in laser intensity signal, the etching endpoint is determined to have been reached. Wherein, the first laser intensity value is the laser intensity received by the first detector (310), and the second laser intensity value is the laser intensity received by the second detector (320); The laser intensity signal abrupt change includes: the first laser intensity value changing from a preset intensity range value to outside the preset intensity range value during the process; and / or, the second laser intensity value changing from an unstable fluctuation state to a stable state during the process.

9. The method according to claim 8, characterized in that, The first laser intensity value is the Raman signal intensity value of the laser received by the first detector (310): the first laser intensity value changes abruptly, including when the real-time Raman signal intensity is outside the first preset magnification range of the average Raman signal intensity, wherein the average Raman signal intensity is obtained from the real-time Raman signal intensity obtained during the etching step.

10. The method according to claim 8 or 9, characterized in that, The second laser intensity value is the reflected signal intensity value of the pulsed laser received by the second detector (320). The second laser intensity value remains stable, including a second preset multiple of the real-time fluctuation value of the reflected signal being less than the cumulative fluctuation value of the reflected signal. The real-time fluctuation value of the reflected signal and the cumulative fluctuation value of the reflected signal are obtained from the real-time reflected signal intensity acquired during the etching step.

11. A semiconductor process apparatus, characterized in that, It also includes an industrial control computer, which includes at least one processor and at least one memory, wherein the memory stores a computer program, and the computer program, when executed by the processor, implements the etching endpoint monitoring method according to any one of claims 8-10.

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