Controllable non-uniform ceramic plate air outlet system and method

Abstract

The invention discloses a controllable non-uniform ceramic plate air outlet system and method for a semiconductor plasma process. The system comprises a double-layer ceramic substrate with a multi-area gas flow channel; the plurality of air outlet hole arrays are arranged on the base body; the detection module is used for monitoring the etching depth of the surface of the wafer in real time; the control unit is used for performing closed-loop feedback control based on the real-time detection data; the air hole opening and closing executing mechanism is driven and controlled by the control unit and executes micro-displacement action according to the control instruction so as to accurately control the opening and closing state and the opening degree of the air outlet holes in the corresponding area. According to the invention, the spatial distribution of the reaction gas in the chamber is dynamically regulated and controlled in a zoned manner, the problem of non-uniform plasma distribution in a traditional scheme is effectively compensated, active control and improvement of wafer processing uniformity are realized, and the method has the advantages of high response speed, high control precision and strong adaptability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing equipment, in particular to a gas distribution system for a process chamber of plasma etching, chemical vapor deposition (CVD) or glue removal, and more particularly to a controllable non-uniform ceramic plate gas outlet system and method capable of actively regulating the spatial distribution of reaction gas above the wafer in real time. BACKGROUND

[0002] In advanced integrated circuit manufacturing, plasma process is a key technology for realizing micro-pattern etching and film deposition. The basic principle is to generate plasma by exciting process gas in a vacuum chamber, and to realize the removal or growth of materials by physical or chemical reaction between active ions, free radicals in the plasma and the wafer surface. After the process is completed, the consistency of etching or deposition thickness at each point on the wafer surface, i.e. uniformity (often measured by U value), is one of the core indicators for evaluating process quality.

[0003] However, the existing solutions are difficult to achieve high uniformity requirements. SUMMARY

[0004] The present application aims to provide a controllable non-uniform ceramic plate gas outlet system and method, which realizes real-time regulation of gas flow field by dynamically adjusting the opening and closing state of the gas outlet hole, thereby improving the processing uniformity.

[0005] The present application provides a controllable non-uniform ceramic plate gas outlet system for a process chamber of a semiconductor manufacturing device, comprising: A ceramic base is internally configured to have a plurality of mutually independent gas flow passage partitions; in a preferred example, the ceramic plate can be made of alumina or aluminum nitride ceramic material, which has good high-temperature resistance and insulation performance; A plurality of gas outlet holes penetrate the lower surface of the ceramic base and are in communication with the gas flow passage partitions for delivering process gas into the process chamber; in implementation, the gas outlet holes can be designed in regions, and in each region, the gas hole structure can be uniform or non-uniform, or the gas hole structure can be the same or different in size; A detection module is used to obtain etching depth data of a plurality of detection points on the wafer surface in real time; in implementation, the detection device can be integrated above the optical window, and the detection principle can be to measure the etching depth in real time by an interferometer principle; A control unit is signal connected with the detection module and the gas hole opening and closing execution mechanism, and is configured to calculate the etching uniformity of the wafer surface according to the etching depth data and generate a control instruction; in implementation, the control unit can be preferably a PLC or an embedded system, and a closed-loop control is realized based on the controller; A gas hole opening and closing execution mechanism corresponding to the gas outlet hole is connected to the control unit and changes the effective flow area of the gas outlet hole according to the control instruction, thereby dynamically adjusting the gas flow of the gas outlet hole in different regions to improve etching uniformity. In implementation, the gas hole opening and closing execution mechanism can preferably be a translatable or rotatable structure (such as a baffle), and the determination mode of the execution action can also preferably be electromagnetic drive or piezoelectric drive and the like, achieving microsecond-level response. In implementation, the driving of the execution mechanism can preferably be motor control, such as a stepper motor or a servo motor and the like.

[0006] Preferably, the ceramic base is a double-layer structure including an upper ceramic plate and a lower ceramic plate joined with the upper ceramic plate, and a groove is formed between the upper ceramic plate and the lower ceramic plate by etching or grinding, and the groove is configured as the mutually independent gas flow channel partitions.

[0007] Preferably, the gas flow channel partitions are radially or fan-shaped symmetrically distributed around the center of the ceramic base, and each partition is connected to an independent gas inlet source or connected to a total gas inlet source through an adjustable valve group arranged upstream of the base.

[0008] Preferably, the gas hole opening and closing execution mechanism includes a gas hole baffle movable relative to the gas outlet hole, and the shape of the gas hole baffle is fan-shaped, rectangular, circular, or a special-shaped structure (such as any polygon) matching the shape of the flow channel partition. In implementation, different shapes and sizes can be selected according to different process requirements; And / or, the gas hole opening and closing execution mechanism includes a micro linear motor, a piezoelectric ceramic driver, or a voice coil motor. In implementation, a servo motor can be selected, which has high-precision position control capability. And / or, the gas hole opening and closing execution mechanism includes a connecting rod to transmit the action within the ceramic base through the connecting rod, and the connecting rod is a rigid link, a flexible hinge, or a bellows structure. In a preferred example, the connecting rod can be made of titanium alloy material, which has high strength and low thermal expansion coefficient.

[0009] Preferably, the gas hole baffle is made of a material matching the thermal expansion coefficient of the ceramic base, and the material is Kovar alloy, titanium alloy, or a metal material coated with a ceramic coating. A flexible sealing layer is arranged between the gas hole baffle and the lower surface of the ceramic base, and the flexible sealing layer is a polyimide film or a metal bellows gasket. And / or, the driving mechanism is a micro linear motor, a piezoelectric ceramic driver, or a voice coil motor, and the driving mechanism is connected to the gas hole baffle through a connecting rod, and the connecting rod is a rigid link, a flexible hinge, or a bellows structure.

[0010] Preferably, the detection module is an interference endpoint detection device (i.e. IEP module) comprising a broadband light source, a beamsplitter, a reference mirror and a spectrometer, which measures the wafer surface through an optical window arranged on the top of the process chamber and calculates the etching depth by analyzing the interference spectrum of the reflected light and the reference light; in implementation, the IEP detection device is integrated with optical sensors, phase difference calculation algorithm and other units, so as to timely output detection data through the interference detection principle; Preferably, the gas outlet holes are unevenly distributed on the lower surface of the ceramic substrate, and a higher density of gas outlet holes and / or a larger diameter of gas outlet holes are arranged in the area where the etching rate is expected to be slower. Preferably, the controllable non-uniform ceramic plate gas outlet system further comprises a pressure sensor array arranged in each gas flow channel partition for monitoring the real-time pressure of each partition, and the control unit is further configured to adjust the gas hole opening and closing actuator and / or the gas inlet valve according to the monitored pressure data to realize the coordinated control of flow and pressure.

[0011] Preferably, the control unit is configured to execute one or more of the following control processes: S1: receiving real-time etching depth data D(x, y, t) from the detection module, where (x, y) is the coordinate of the detection point and t is the time; S2: calculating the etching uniformity index U value of the wafer surface at the current time, the index U value being the standard deviation or range value of all detection point depth values; S3: comparing the index U value with a preset threshold U0, if U>U0, it is determined that the uniformity is not up to standard, and step S4 is executed; S4: analyzing the spatial distribution of the depth data D to identify areas where the etching rate is too slow and areas where the etching rate is too fast; S5: generating control instructions according to the identification results: increasing the opening of the gas outlet holes above the areas where the etching is too slow, and / or reducing the opening of the gas outlet holes above the areas where the etching is too fast; S6: sending the control instructions to the gas hole opening and closing actuator to execute the fine tuning action of changing the effective flow area of the gas outlet holes.

[0012] Preferably, a process model is pre-stored in the control unit, the process model pre-setting a mapping relationship between the etching depth distribution and the opening and closing state of the gas outlet holes, and the generation of the control instructions is based on the combination of feedforward control and closed-loop feedback control of the process model.

[0013] Preferably, the process model is a neural network model trained based on a machine learning algorithm, the input of which includes historical etching depth data, current process parameters and gas outlet hole state, and the output is the optimized gas outlet hole control instruction.

[0014] The application also provides a gas flow control method based on any of the systems, comprising the steps of: Real-time monitoring of the etching depth distribution of the wafer surface by the detection module; According to the etching depth distribution, determining whether the etching uniformity deviates from the expectation; If it deviates from the expectation, controlling the action of the gas hole opening and closing actuator to adjust the gas hole opening and closing degree execution state to change the gas flux of the corresponding area gas hole, thereby correcting the spatial distribution of the reaction gas in the chamber and improving the plasma density uniformity.

[0015] Compared with the prior art, the application has the following beneficial effects: The application solves the long-standing uniformity problem in plasma process in semiconductor manufacturing by adopting the innovative "perception-decision-execution" closed-loop control system. The technical effects brought about in solving the problem can be embodied in one or more of the following aspects: On the one hand, the closed-loop control architecture of "perception-decision-execution" is creatively adopted to realize real-time dynamic regulation and control of the wafer processing process; On the other hand, the detection (such as the IEP module) and the gas hole actuator are integrated and designed as a closed loop, so that the response speed is faster than that of the traditional gas path control mode, for example, the response speed is 10-100 times that of the traditional gas path; Thirdly, the modular design and the gas hole partition control design facilitate flexible adjustment of the control strategy of the process gas according to different process requirements, thereby improving the flexibility of uniformity control; Fourthly, CTE matching materials and flexible sealing design are adopted to solve the reliability problem of the actuator in a high-temperature vacuum environment; Fifthly, the system can collect and generate a large amount of process data, so that these process books can construct an intelligent process model based on machine learning algorithms in later process optimization, thereby facilitating the realization of the process route from passive response optimization to active prediction after the model is embedded into the control system. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a closed-loop control schematic diagram of the ceramic plate of the application forming a controllable non-uniform gas flow field; Figure 2 is a vertical cross-sectional schematic diagram of the controllable non-uniform ceramic plate gas outlet system in the application; Figure 3 is a horizontal cross-sectional schematic diagram of the controllable non-uniform ceramic plate gas outlet system in the application; Figure 4 is a control unit workflow schematic diagram of the controllable non-uniform ceramic plate gas outlet system in the application; Figure 5It is a controllable non-uniform ceramic plate gas outlet system gas flow control method flow chart. DETAILED DESCRIPTION

[0017] The embodiments of the present application will be described in detail below with reference to the drawings.

[0018] The above embodiments of the present application are described with reference to the drawings, and all other embodiments obtained by those of ordinary skill in the art based on the description, as well as modifications or changes thereto, are within the scope of the present application.

[0019] It should be noted that various aspects of the embodiments described below are within the scope of the appended claims. It should be apparent that the aspects described herein can be implemented in a wide variety of forms and that any specific structure and / or function described herein is merely illustrative. Based on the teachings herein one skilled in the art should appreciate that an aspect described herein can be implemented independently of any other aspects and that an aspect described herein can be implemented both as any number of software and / or hardware structures.

[0020] It should also be noted that the graphical illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present application, and the figures only show the components related to the present application, not the number, shape and size of the components when actually implemented, and the shapes, numbers and proportions of the components when actually implemented can be arbitrarily changed, and the layout of the components can also be more complex.

[0021] In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, one skilled in the art will understand that the application can be practiced without these specific details.

[0022] In semiconductor plasma processes, achieving high uniformity (U value) of wafer processing is a long-term goal of the industry, and is also an extremely complex technical problem.

[0023] In the prior art, a fixed gas distribution plate, also known as a showerhead, is usually used. The size and distribution of the gas outlet holes on the plate are fixed and unchangeable after pre-simulation and design, aiming to provide an initial and static uniform gas flow.

[0024] Through long-term research and a large number of experiments, the present application has a deep understanding that the root cause of uniformity is the spatial asymmetry of the distribution of the reaction gas and the plasma in the process chamber. This asymmetry is inherent and dynamic.

[0025] On the one hand, the inherent cause is that it is usually caused by the congenital limitation of the physical structure of the equipment. For example, the static design cannot cope with the above-mentioned dynamic and random interference factors, and cannot adapt to different gas flow and pressure requirements under different process formulations. In particular, when the process conditions change or the state of the parts drifts after long-term operation of the equipment, the original optimal design may fail, resulting in poor uniformity. For example, it is difficult to achieve absolute symmetry in the physical structure of the process chamber. In order to maintain a vacuum, the chamber is usually connected with a pump port, and the existence of the pump port destroys the symmetry of the chamber, resulting in inherent differences in the gas flow field and the distribution of the plasma in the area at different distances from the pump port, forming the so-called "pumping effect". For another example, the Lorentz force of the geomagnetic field on the motion trajectory of charged particles (electrons, ions) is weak, but at the nanoscale processing scale, the systematic east-west or north-south deviation caused by it cannot be ignored. In addition, the feed-in point of the radio frequency power, the uneven loss of the inner wall surface of the chamber, etc. all introduce inherent asymmetry sources that cannot be completely eliminated by mechanical design.

[0026] On the other hand, the dynamic cause is that the process is not static. Different process formulations (such as gas types, flow, pressure, and radio frequency power) of different products will cause changes in plasma impedance and distribution. In addition, after years of operation of the equipment, the state of the chamber inner wall cleanliness and part aging will drift, which is called "process drift", so that the static gas distribution plate that is adjusted to be optimal at the time of equipment acceptance will start to deteriorate in process uniformity after a few months or even weeks.

[0027] Therefore, the core defect of the prior art is its "static" and "passive" nature. Neither the uniformly distributed gas distribution plate nor the gas system that can only be manually pre-adjusted in zones can cope with the above-mentioned inherent and dynamic non-uniformity challenges.

[0028] Therefore, the industry urgently needs a technical solution that can dynamically and real-time adjust the gas distribution to actively compensate for the non-uniformity caused by various factors and stabilize the U value of the process within the optimal range.

[0029] In other words, the inventive motivation of the present application stems from a strong technical demand: whether to create a "smart" gas distribution system that can not only "see" (i.e., perceive) the real-time non-uniformity of the wafer surface processing state, but also "think" (i.e., decide) the reason, and immediately "act" (i.e., execute) the dynamic adjustment of the spatial distribution of the gas, so as to actively and in real time compensate for the non-uniformity caused by various factors. Therefore, if "sensing", "decision", and "actuation" can be integrated into one, and then form a closed-loop control concept, it will help to solve the aforementioned problems.

[0030] Based on the above analysis, the present application proposes a revolutionary technical concept: referring to Figure 1 In summary, the traditional "static gas distribution" concept is transformed into the "dynamic airflow field regulation" concept. The concept of the present application includes the following core ideas that are closely linked and mutually supported: On the one hand, global real-time sensing ("eyes"): using monitoring means, it can "see" like "eyes" that the etching or deposition depth of each point on the wafer surface is occurring in real time, rather than only knowing the result through sampling inspection after the process is completed.

[0031] In implementation, optical detection technology can be used as a sensing means, such as interference endpoint detection (IEP), which can calculate the real-time change and spatial distribution of etching depth with nanometer-level precision by continuously measuring the optical path difference between the wafer surface reflected light and the reference light during the process. This provides unprecedented, high-precision, and full-field data input for closed-loop control.

[0032] On the other hand, intelligent decision and control ("brain"): taking appropriate decision mechanisms, just like a "brain" can quickly process the information seen by the "eyes", judge the pattern and degree of non-uniformity, and calculate the best correction strategy.

[0033] In implementation, a high-speed control unit can be designed, and the control algorithm built-in the high-speed control unit first converts the IEP data into real-time uniformity indicators, such as within-wafer non-uniformity (WIWNU), and compares it with the set threshold. Once the error is exceeded, the process model is called. The model can be a simple mapping based on physical principles (such as "A area is thin, give A area more point gas"), or a more advanced neural network model based on machine learning training. The latter can learn the complex nonlinear relationship in historical process data, realize intelligent mapping from "current depth distribution" to "optimal gas hole adjustment instruction", and even perform feedforward prediction to take action in advance.

[0034] Three aspects, fast and accurate execution ("hand"): according to the decision and instruction given by the foregoing "brain", the corresponding dynamic control can be executed in time and accurately, just like a pair of "dexterous hands", which can faithfully execute the instructions issued by the "brain", and dynamically adjust the gas distribution with micron level and millisecond level precision.

[0035] In implementation, the execution function can be implemented through the creative physical implementation. For example, the slow scheme of traditionally adjusting the upstream gas path valve is abandoned, and the micro actuator (such as a motor / piezoelectric driver) is creatively integrated on the ceramic gas distribution plate. By designing the gas hole baffle mechanism, the actuator drives it to make a small displacement, directly controlling the effective opening of each or each group of gas outlet holes. This "terminal regulation" method saves the long gas delivery pipeline delay, so that the response speed is improved from "tens of seconds" in the traditional scheme to "millisecond-second level", which matches the dynamic change speed of the plasma process.

[0036] It should be noted that the above three core concepts are interdependent and indispensable: for example, without IEP real-time perception, decision and execution control are useless; without intelligent decision, complex data cannot be processed and the optimal solution cannot be given; without a fast execution mechanism, a good decision cannot be implemented, and a closed loop cannot be formed.

[0037] The closed-loop cooperative process of "perception-decision-execution" described above is the fundamental difference between the present application and all existing technologies.

[0038] It should be noted that in the process of converting the above technical concept into an implementable technical solution, the present application also innovatively proposes a series of carefully designed.

[0039] For example, the integration of high-temperature-resistant and high-precision execution mechanisms in the vacuum chamber. The plasma process chamber is in a high-vacuum, high-temperature environment, and there is a strong electromagnetic field. Conventional motors are difficult to work stably in this environment, and the particle contaminants and magnetic field interference they may produce are unacceptable. The present application proposes a feasible solution: preferably a non-magnetic, high-temperature-resistant micro voice coil motor or piezoelectric ceramic driver, and through a vacuum feedthrough installation method, the drive mechanism can be installed outside the reaction environment chamber, and the motion is transmitted to the execution mechanism (such as a gas hole baffle) inside the chamber through a rigid connecting rod or a flexible bellows transmission mechanism, thereby isolating the drive components that are prone to problems from the harsh reaction environment in the chamber, perfectly solving the compatibility problem.

[0040] For example, in terms of ensuring long-term reliable airtightness. Since the movable orifice shutter must maintain extremely high airtightness with the fixed ceramic plate to prevent gas leakage to the wrong area, while being resistant to plasma corrosion, high temperature, and having a low friction coefficient. The present application proposes a feasible solution: a flexible sealing scheme is adopted. A layer of ultra-thin flexible sealing film, such as polyimide (PI) or Teflon (PTFE), is added between the metal shutter and the ceramic plate, so that the film has good elasticity, heat resistance, and chemical inertness, etc. It can not only effectively realize sealing, but also reduce the resistance influence of the slight movement of the shutter (i.e. almost no resistance or very small resistance). In the preferred mode, a metal bellows can be used as a dynamic seal to achieve completely frictionless sealing.

[0041] For example, in terms of thermal matching and thermal management. Because the temperature of the ceramic plate will rise during the process, the mismatch of the coefficient of thermal expansion (CTE) between the ceramic plate and the metal shutter and connecting rod will generate thermal stress, causing jamming or positioning accuracy error. The present application proposes a feasible solution: the key structural parts are designed with CTE matching. For example, Kovar or Invar is used to make the orifice shutter and connecting rod, because its CTE is very close to that of alumina ceramic, which can greatly inhibit thermal stress.

[0042] For example, in terms of the practicality of the control algorithm. Generally speaking, the plasma process control system is a very complex nonlinear system, and it is extremely difficult to establish an accurate physical model for the control process. The present application proposes a feasible solution: a data-driven machine learning method is adopted. By collecting a large amount of IEP data, orifice state and final uniformity results under different process conditions, a convolutional neural network (CNN) or recurrent neural network (RNN) model is trained. This model can automatically learn the complex relationship between them, without the need for accurate physical equations to achieve high-quality control. The model is embedded into a real-time industrial controller (such as an industrial computer, PLC, etc.) to realize intelligent closed-loop control.

[0043] In summary, the successful implementation of the technical concept brings unexpected technical effects: First, from "static preset" to "dynamic self-adaptive": the existing technology can at most perform static, preset flow regulation for different partitions, and cannot respond to random dynamic disturbances in the process.

[0044] Second, from "open loop" to "closed loop" paradigm shift: the semiconductor manufacturing process is first changed from an "open loop mode of preset formula and expected results" to an "intelligent closed loop process of real-time sensing, dynamic adjustment, and ensuring results" in this application scenario, bringing a quantitative improvement in uniformity and realizing a qualitative leap.

[0045] Thirdly, the core engineering problem of "time lag" is solved: the traditional scheme cannot realize effective closed-loop control due to slow response of the actuator (such as a regulating valve) and long control cycle, even if there is detection. The present application realizes millisecond to second level response speed by directly integrating the execution structure on the gas distribution plate, which matches the time constant of the process and improves the response speed by one to two orders of magnitude, making real-time closed-loop control truly possible. This is a new function that the prior art has not suggested or realized.

[0046] Fourthly, it has strong anti-interference and self-adaptive ability: whether it is chamber pressure fluctuation, RF power jump, or device state drift, the system can automatically compensate through closed-loop feedback, significantly improving the robustness and repeatability of the process.

[0047] Fifthly, it opens up a new way for process optimization: the system can collect and generate a large amount of process data, providing a data basis for future process optimization, such as deep analysis and machine learning iteration, so that the process model can be continuously optimized, and even better process windows that cannot be found by artificial means can be found, making the equipment more intelligent.

[0048] Therefore, the technical concept of the present application is not a simple improvement or combination of the prior art, but a new and systematic solution to the long-standing fundamental problem in the industry. It creatively integrates real-time detection, intelligent decision-making, and terminal execution into one, forming an organic and dynamic intelligent control system, and ultimately realizing the fundamental improvement of process uniformity.

[0049] The various embodiments will be illustrated below with examples.

[0050] Embodiment one: basic controllable non-uniform ceramic plate gas outlet system Referring to Figure 2 and Figure 3 , the present application provides a controllable non-uniform ceramic plate gas outlet system arranged in the process cavity, which can include: a ceramic base 10, a gas hole opening and closing execution mechanism 20, a detection module (not shown in the figure) and a control unit (not shown in the figure).

[0051] In some examples, the ceramic base 10 is located above the wafer 1 and wafer carrier 2, and is made of high-purity Al2O3 or AlN ceramic material through a sintering process, and has good insulation, corrosion resistance and mechanical strength. Among them, the ceramic base 10 can be made of high-purity (such as 99.6%) aluminum oxide (Al2O3) ceramic material, and is formed by isostatic pressing and high-temperature sintering (such as at 1650°C, holding for 4 hours), so that the excellent insulation performance, high mechanical strength (such as bending strength > 300MPa) and good plasma etching resistance of Al2O3 can be utilized. When using aluminum nitride (AlN) ceramic, its higher thermal conductivity can be utilized, which can better adapt to high-power occasions.

[0052] In some examples, the ceramic base 10 is preferably a double-layer structure, including an upper ceramic plate and a lower ceramic plate bonded to the upper ceramic plate, and a groove is formed between the upper ceramic plate and the lower ceramic plate, which is configured as a gas flow channel partition independent of each other. For example, a series of radially distributed grooves are machined on the upper surface of the lower ceramic plate and / or on the lower surface of the upper ceramic plate through etching (photolithography and reactive ion etching, etc.) or grinding process. These grooves form a plurality of mutually isolated fan-shaped gas flow channel partitions after the upper and lower ceramic plates are bonded. One end of each flow channel partition is connected to an independent gas inlet, and the other end is connected to a series of precisely machined gas outlet holes 110. For example, the ceramic base is a precisely designed double-layer structure, the upper ceramic plate has a thickness of 3.0mm, a flatness tolerance of <0.05mm, and a surface roughness Ra of <0.4μm; the lower ceramic plate has a thickness of 2.5mm and is processed with precise flow channels through photolithography and reactive ion etching (RIE) process.

[0053] In some examples, the radially distributed grooves are made only on the upper surface of the lower ceramic plate through a photolithography process. For example, the groove depth is 0.8mm±0.05mm, the groove width is 1.2mm±0.1mm, the number of partitions is 12 fan-shaped regions (each with a 30° central angle), and each fan-shaped region is completely isolated to prevent gas crosstalk.

[0054] In some examples, the gas flow channel partitions are radially or fan-shaped symmetrically distributed around the center of the ceramic base, and each partition is connected to an independent gas source or connected to a total gas source through an adjustable valve group arranged upstream of the base, so as to realize flexible control of different gas flow channels and partitions.

[0055] In some examples, the diameter of the gas outlet holes 110 is between 0.1 mm and 0.5 mm, and is distributed in different sectors, which can have the same or different distribution density. For example, in the area close to the pump port, the density is set to be higher to pre-compensate for the asymmetry of the gas flow. For example, the gas outlet holes 110 in the central area have a smaller spacing, while the gas outlet holes 110 in the peripheral area of the central area have a larger spacing. For example, the hole spacing is 1.5 mm in the area close to the pump port to form a high-density gas hole area, and 3.0 mm in the area away from the pump port to form a low-density gas hole area. For example, the gas outlet holes are non-uniformly distributed on the lower surface of the ceramic substrate, which facilitates the setting of higher gas hole density and / or larger gas hole diameter in the area where the etching rate is expected to be slower.

[0056] In some examples, the shape (i.e. hole type) of the gas outlet holes 110 can be set as a tapered hole, which has a slightly larger diameter at the inlet side than at the outlet side, thereby reducing the gas flow resistance.

[0057] In some examples, the gas hole baffle 230 has a shape of a sector, a rectangle, a circle, or a special-shaped structure matching the shape of the flow channel partition.

[0058] In some examples, the gas hole baffle is made of a material matching the thermal expansion coefficient of the ceramic substrate, wherein the material is Kovar alloy, titanium alloy, or a metal material coated with a ceramic coating.

[0059] For example, the gas hole baffle 230 is made of 4J29 Kovar alloy, which has a thermal expansion coefficient close to that of Al2O3 ceramic, thereby reducing the influence of thermal stress. In addition, the thickness of the baffle is preferably 0.8 mm, and the surface is treated with chemical nickel plating (such as a thickness of 8 μm), thereby improving corrosion resistance and surface hardness.

[0060] In some examples, a flexible sealing layer is provided between the gas hole baffle 230 and the lower surface of the ceramic substrate, and the flexible sealing layer is preferably a polyimide film or a metal corrugated gasket material layer. For example, the sealing layer is a 25 μm thick polyimide film, which is pasted to the surface of the baffle with high-temperature resistant adhesive.

[0061] In some examples, the gas hole opening and closing actuator can include a driving motor 210, wherein the motor can be preferably a micro linear motor, a piezoelectric ceramic driver, or a voice coil motor. For example, a voice coil motor is used for direct driving, which can avoid the backlash problem existing in traditional lead screw or gear transmission, and can achieve a millisecond-level dynamic response, which can follow the rapid fluctuations that can occur in the plasma process (such as instantaneous non-uniformity caused by RF power jump).

[0062] In some examples, the gas hole opening and closing actuator can include a connecting rod 220 to perform action transmission in the ceramic base through the connecting rod 220. In examples, the connecting rod 220 can be a rigid connecting rod, a flexible hinge or a bellows structure. For example, the connecting rod 220 is preferably a rigid rod of 316L stainless steel material (such as a rigid rod with a diameter of 6mm), which is connected with the baffle by a self-centering ball hinge (such as a ball head with a radius of 3mm), which compensates for the displacement caused by installation centering error (up to ±0.5mm) and thermal deformation, and realizes higher precision control of the small displacement of the baffle.

[0063] In some examples, the control unit is configured to acquire data and process the data. Referring to Figure 4 For example, the control unit can perform one or more of the following control processes.

[0064] For example, the control unit receives real-time etching depth data D(x,y,t) from the interference endpoint detection device (i.e. IEP module), where (x,y) is the detection point coordinate and t is the time. Among them, IEP can provide high-precision, full-field depth data, providing unprecedented data support for zoned fine-tuning, and the ability of zoned fine-tuning maximizes the value of IEP data.

[0065] For example, the control unit calculates the etching uniformity index U value of the wafer surface at the current time, and the index U value is the standard deviation or range value of all detection point depth values.

[0066] For example, the control unit compares the index U value with a preset threshold U0, and if U>U0, it is determined that the uniformity is not up to standard.

[0067] For example, the control unit analyzes the spatial distribution of the depth data D to identify areas where the etching rate is too slow and areas where the etching rate is too fast.

[0068] For example, the control unit generates control instructions according to the identified spatial distribution results: increase the opening degree of the upper gas hole corresponding to the area where the etching is too slow, and / or reduce the opening degree of the upper gas hole corresponding to the area where the etching is too fast.

[0069] For example, the control unit sends the control instructions to the driving mechanism to drive the gas hole opening and closing actuator to act.

[0070] In some examples, the detection module is preferably an IEP module (i.e. interference endpoint detection device), which includes a broadband light source, a beam splitter, a reference mirror and a spectrometer, and the interference endpoint detection device passes through an optical window (see the foregoing Figure 2The wafer surface is measured, and the etching depth is calculated by analyzing the interference spectrum of the reflected light and the reference light. It should be noted that the IEP module can be a mature commercial product or a product improved for different applications, and is not limited here.

[0071] In some examples, in the gas flow control, the real-time pressure can also be sensed by the pressure sensor array for fine control. In implementation, the pressure sensor array is arranged in each gas flow channel partition for monitoring the real-time pressure of each partition, and the control unit is further configured to adjust the gas hole opening and closing actuator and / or the gas inlet valve (such as the valve arranged on the pipeline) according to the monitored pressure data, to realize the coordinated control of the flow and the pressure. For example, when the gas pressure deviates from the target value, the gas inlet valve can be adjusted to quickly reach the required gas pressure range, and when the gas pressure deviates from the target value, the gas hole opening and closing actuator can be adjusted to perform fine movement to achieve high-precision adjustment.

[0072] Embodiment two: concentric ring partition and rotary driving scheme This embodiment provides an alternative implementation, which adopts a concentric ring-shaped gas flow channel partition design suitable for applications where the wafer edge effect is significant.

[0073] In some examples, the ceramic substrate 10 adopts a multi-layer composite structure: the base layer is 2.0 mm thick AlN ceramic, which provides good thermal conductivity; the flow channel layer is 1.5 mm thick Al2O3 ceramic, which is processed with a concentric ring-shaped flow channel; and the gas outlet surface is 1.0 mm thick Al2O3 ceramic, which is processed with a micro-hole array.

[0074] In some examples, the concentric ring-shaped flow channel design parameters: the number of rings adopts 5 independently controlled ring areas; the ring width: from the center to the edge, it is 15 mm, 20 mm, 25 mm, 30 mm, and 40 mm; the isolation method: each ring area is isolated by a 0.5 mm wide sealing wall.

[0075] In some examples, the rotary gas hole opening and closing mechanism: the gas hole baffle 230 is designed as a disc-shaped structure with the same diameter as the ceramic substrate, a thickness of 1.2 mm, and a material of Invar 36, which has a very low thermal expansion coefficient to ensure dimensional stability at high temperatures; the baffle is processed with an arc-shaped hole array corresponding to the gas outlet hole 110, and the opening degree is controlled by accurate rotation, wherein the hole type is a sector hole with an angle of 10°, and the radial length is adjusted according to the ring area; the opening degree control is the rotation angle of 0-30°, corresponding to the opening degree of 0-100%; the resolution: the rotation angle resolution is 0.1°, corresponding to a change of about 0.3% in opening degree.

[0076] In some examples, the driving motor 210 adopts a combination of a servo motor + precision reducer (reduction ratio 50:1), with a rated torque of 2.5 N·m, a maximum speed of 6000 rpm, a positioning accuracy of ±5 angular seconds, a repeat positioning accuracy of ±1 angular second, and an absolute encoder (23-bit resolution) directly installed on the motor shaft to provide real-time position feedback.

[0077] In some examples, the detection module adopts a white light interferometer to replace the standard IEP system to provide full-field three-dimensional topography measurement and simultaneously obtain etching depth and surface roughness information.

[0078] In summary, the concentric ring partitioning example can generally have one or more of the following characteristics: better match the process characteristics of wafer rotational symmetry; although the control accuracy of the central region is relatively low, it can more effectively handle the non-uniformity problem of the edge region; the number of ring partitions is relatively small (usually 5-7 rings), and the control system is relatively simple; the rotating drive mode structure is compact and saves space. Therefore, the applicable scenarios can be: post-CMP (chemical mechanical polishing) cleaning; plasma enhanced chemical vapor deposition (PECVD) with strong rotational symmetry; advanced packaging processes with extremely high edge uniformity requirements, etc.

[0079] Embodiment three: controllable non-uniform ceramic plate gas outlet system with certain intelligence and prediction In some examples, a process model is pre-stored in the control unit, wherein the process model can be pre-set with a mapping relationship between etching depth distribution and gas outlet hole opening and closing state, such as a "mapping relationship between etching depth distribution and gas outlet hole opening degree data located in different regions" obtained from production experience, so as to form a control instruction in real time according to the mapping relationship, so that the generation of the control instruction can be based on the process model to combine feedforward control and closed-loop feedback control. The closed-loop control here refers to the closed-loop control process between the detection unit, the control unit and the actuator in the foregoing examples.

[0080] Based on the process model, a real-time control strategy can be implemented, in which the system adopts a composite control strategy of predictive feedforward + feedback correction. For example, the feedforward control (main role) adjusts the opening degree of the gas outlet hole 10-30 seconds in advance, and timely responds to common disturbances: RF power change, process recipe switching, chamber temperature drift, etc. For example, the feedback correction control (auxiliary role) is based on real-time IEP measurement data to make small corrections and flexibly respond to unpredictable disturbances: gas purity fluctuation, equipment random noise.

[0081] In some examples, a large amount of real-time process data can be obtained by the system, and thus a new process model can be trained by artificial intelligence in the later stage to achieve a certain intelligence and prediction capability of the process model. In implementation, a neural network model trained based on a machine learning algorithm is used as the process model, wherein the input of the neural network model includes historical etching depth data, current process parameters, and gas outlet hole state, and the output is an optimized gas outlet hole control instruction.

[0082] In the intelligent process model, an adaptive learning mechanism can also be used, for example, the system automatically performs model updating every week, for example, collects new process data (about 500 data points), incrementally trains, retains the old model version, and can be rolled back if necessary.

[0083] By introducing the machine learning model, the system can not only perform passive feedback compensation, but also perform active feedforward prediction. For example, the model learns that when the RF power of a certain mode jumps, it usually causes non-uniformity at a specific orientation of the wafer edge, and thus the opening degree of the gas hole in the corresponding area can be adjusted in advance before the non-uniformity is actually detected by the IEP, achieving more advanced and more accurate control, and significantly improving the control quality and process stability.

[0084] Embodiment Four: Piezoelectric Drive and Micro-hole Array Structure On the basis of the above embodiments, the present application can also achieve precise control of the opening and closing degree of the gas outlet hole in another way.

[0085] In this embodiment, the gas hole opening and closing execution mechanism 20 is not in the form of a translational baffle, but is composed of a piezoelectric actuator array. A micro piezoelectric ceramic unit (not shown in the figure) is arranged above each gas outlet hole 110 of the ceramic base 10. When each piezoelectric ceramic unit is not powered, its length is slightly larger than the height of the flow channel, and the sealing plug (which can be made of polyether ether ketone PEEK or rubber material) at its lower end is pressed against the upper end of the gas outlet hole under the action of the pre-tightening force, achieving closing. When a voltage is applied to the piezoelectric ceramic unit, it will produce a reverse piezoelectric effect, causing axial contraction, driving the sealing plug to displace upward, thereby opening the gas outlet hole. The opening and closing degree can be accurately controlled by the applied voltage value.

[0086] Through independent and digital control of each gas outlet hole, the highest level of control accuracy is achieved. It omits the complex mechanical transmission mechanism and has extremely fast response speed (up to microseconds). It is particularly suitable for advanced processes that require extremely high uniformity control.

[0087] Embodiment Five: Application of Thermal Expansion Drive and Shape Memory Alloy This embodiment provides another example of realizing the opening and closing of the gas hole, which uses the principle of thermal drive.

[0088] The air hole baffle 230 is made of bimetallic sheet or shape memory alloy (SMA, such as Nitinol). One end of the baffle is fixed, and the other end is a free end corresponding to covering a group of air outlet holes. The driving mechanism is a micro-heating resistor integrated near the baffle, and the control unit accurately controls the temperature of the baffle by controlling the current flowing into the heating resistor. When the temperature changes, the bimetallic sheet will bend due to the difference in thermal expansion coefficient of the two sides of the material; or the shape memory alloy will undergo a phase change and restore its memory shape, thereby generating displacement and realizing control of the opening degree of the air outlet holes below.

[0089] The example structure is simple, does not require motor and other moving parts, has high reliability, and is very suitable for ultra-clean environments with extremely high cleanliness requirements. The shape memory alloy has the advantages of large driving force and high displacement accuracy.

[0090] Example seven: control unit control strategy optimization This example provides further optimization of the control unit. For example, in the initial stage, rule-based control (such as PID control) can be used to quickly suppress major non-uniformity. When the process enters the stable stage, it can be switched to a high-precision control or adaptive control mode to further optimize the control effect and reduce overshoot.

[0091] More preferably, the system can have a self-learning function. After each process is completed, the system stores the full-process data of this process (sensor data, control instructions, and final uniformity results) into a database. Periodically, these data are used to incrementally train and fine-tune the internal process model (such as the neural network model of the aforementioned example), so that the model can continuously adapt to changes in device state (such as changes in chamber cleanliness), thereby achieving the effect of becoming more intelligent over time. By having continuous learning ability, the system has better flexibility and precision compared to any fixed parameter control scheme.

[0092] Example six: method for forming controllable non-uniform gas flow by ceramic plate This example is based on the controllable non-uniform ceramic plate air outlet system provided in any of the preceding examples, and realizes accurate control of the opening degree of the air outlet holes in the ceramic plate through a closed-loop control method, so as to form a controllable non-uniform gas flow to actively and in real time improve the spatial distribution of the reaction gas above the wafer.

[0093] Reference Figure 5 In summary, the gas flow control method provided by the present application can include: S202, Real-time monitoring of etching depth distribution on wafer surface by detection module. In implementation, wafer surface etching depth data can be acquired in real time by IEP module, for example, data acquisition parameters: sampling frequency is 10 Hz (acquire full field data once every 0.1 second), measurement point number is 49 points (7x7 array, covering the full surface of 300 mm wafer), measurement accuracy is ±0.5 nm (3σ value), data format uses two-dimensional matrix D(x, y, t), where x, y are coordinate indexes, and t is time stamp. In collection, multiple averaging (usually 5 times averaging) can also be used to reduce random noise, reference standard piece real-time calibration can also be performed every 30 minutes to eliminate system drift, and data integrity check can also be performed by detecting data loss, triggering alarm when loss exceeds 10%, which is beneficial to improve data accuracy.

[0094] S204, According to the etching depth distribution, whether the etching uniformity deviates from the expectation is judged. In implementation, the uniformity index can take the within-wafer non-uniformity (WIWNU) as the main discriminant index, and the range / mean, 3σ value, etc. as auxiliary judgment index.

[0095] S206, If it deviates from the expectation, the action of the gas hole opening and closing execution mechanism is controlled, the opening and closing degree of the gas hole is adjusted, the state of execution is adjusted, the gas flux of the corresponding area gas hole is changed, the spatial distribution of the reaction gas in the chamber is corrected, and the plasma density uniformity is improved. In implementation, the threshold setting can be a target value U0 (usually 1.5-2.0%) set according to process requirements. In some examples, simple linear regression analysis can also be used to predict the WIWNU trend in the last 30 seconds, and if the WIWNU is predicted to exceed the threshold in the next 60 seconds, the control action can be triggered in advance.

[0096] In some examples, the control process can be one or each of the following examples. For example, the control resolution can be 0.1% opening degree (corresponding to gas hole baffle displacement accuracy ±1 μm); for example, the response time: from instruction issuance to execution completion <100 ms; for example, using sequential control: to avoid gas flow mutation, using ramp adjustment method; for example, adjustment rate: 5% / s (i.e. from full close to full open about 20 seconds); for example, region sequence: execute according to problem severity priority, etc.

[0097] In some examples, the control process can increase some safety protection mechanism. For example, limit position protection: physical limit + software limit (opening degree 0-100%); for example, mutation protection: single adjustment amount limit (<20%); for example, interlock protection: interlocked with plasma power, keep current state when abnormal, etc.

[0098] In some examples, the control process can employ multi-parameter coordinated control. For example, gas flow and pressure coordination: adjusting the orifice opening while coordinating the upstream pressure control valve; for example, temperature compensation control: adjusting the gas temperature or flow according to the wafer temperature distribution; for example, RF power matching: adjusting the RF matching network parameters in coordination according to the plasma impedance changes, etc.

[0099] The above method realizes precise control of wafer surface etching uniformity through real-time monitoring, intelligent decision-making and precise execution of closed-loop control, and also realizes simultaneous improvement of uniformity and response speed. For example, in terms of uniformity improvement, WIWNU is stably controlled at 1.2-1.8% from 5-8% of the traditional method; in terms of response speed improvement, the response time to process disturbance is only tens of seconds (for example, less than 15 seconds), and the method is suitable for various process recipes without the need for excessive debugging.

[0100] Therefore, based on closed-loop control, precise control of the wafer etching process is realized, and the stability of the semiconductor manufacturing process and the product yield are significantly improved.

[0101] In the specification, the same or similar parts among various embodiments can be referred to each other, and each embodiment focuses on the difference from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the part of the foregoing embodiments.

[0102] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A controllable non-uniform ceramic plate gas outlet system for use in the process chamber of semiconductor manufacturing equipment, characterized in that, include: The ceramic matrix is ​​internally structured with multiple independent gas flow channel zones. Multiple vent holes penetrate the lower surface of the ceramic substrate and are connected to the gas flow channel partition for conveying process gas into the process chamber. The detection module is used to acquire etching depth data of multiple detection points on the wafer surface in real time; The control unit, which is signal-connected to the detection module and the pore opening / closing actuator, is configured to calculate the etching uniformity of the wafer surface based on the etching depth data and generate control commands. An air vent opening and closing actuator is provided corresponding to the air vent, is connected to the control unit, and changes the effective flow area of ​​the air vent according to the control command, thereby dynamically adjusting the gas flow rate of the air vent in different areas to improve etching uniformity.

2. The controllable non-uniform ceramic plate gas outlet system according to claim 1, characterized in that, The ceramic substrate has a double-layer structure, including an upper ceramic plate and a lower ceramic plate joined to the upper ceramic plate. Grooves are formed between the upper ceramic plate and the lower ceramic plate by etching or grinding, and the grooves are configured as independent gas flow channel partitions.

3. The controllable non-uniform ceramic plate gas outlet system according to claim 2, characterized in that, The gas flow channel partitions are symmetrically distributed radially or in a fan shape around the center of the ceramic substrate. Each partition is connected to an independent air intake source or connected to the main air intake source through an adjustable valve group located upstream of the substrate.

4. The controllable non-uniform ceramic plate gas outlet system according to claim 1, characterized in that, The vent opening and closing actuator includes a vent baffle that can move relative to the vent, and the vent baffle is fan-shaped, rectangular, circular, or an irregular structure that matches the shape of the flow channel partition. And / or, the vent opening and closing actuator includes a miniature linear motor, a piezoelectric ceramic driver, or a voice coil motor; And / or, the pore opening and closing actuator includes a connecting rod to transmit the action within the ceramic matrix, the connecting rod being a rigid connecting rod, a flexible hinge, or a bellows structure.

5. The controllable non-uniform ceramic plate gas outlet system according to claim 4, characterized in that, The pore baffle is made of a material whose coefficient of thermal expansion matches that of the ceramic matrix, such as Kovar alloy, titanium alloy, or a metal material with a ceramic coating on its surface. And / or, a flexible sealing layer is provided between the pore baffle and the lower surface of the ceramic substrate, wherein the flexible sealing layer is a polyimide film or a metal corrugated gasket.

6. The controllable non-uniform ceramic plate gas outlet system according to claim 1, characterized in that, The control unit is configured to execute one or more of the following control procedures: S1: Receive real-time erosion depth data D(x,y,t) from the detection module, where (x,y) are the coordinates of the detection point and t is the time. S2: Calculate the etching uniformity index U value of the wafer surface at the current moment, where the index U value is the standard deviation or range value of the depth values ​​of all detection points; S3: Compare the index U value with a preset threshold U0. If U>U0, it is determined that the uniformity does not meet the standard, and step S4 is executed. S4: Analyze the spatial distribution of depth data D to identify areas with excessively slow and excessively fast etching rates; S5: Based on the recognition results, generate control instructions: increase the opening of the vent above the area with slow etching, and / or decrease the opening of the vent above the area with fast etching. S6: Send a control command to the vent opening / closing actuator to perform a fine-tuning action that changes the effective flow area of ​​the vent.

7. The controllable non-uniform ceramic plate gas outlet system according to claim 1, characterized in that, The control unit has a pre-stored process model, which has a preset mapping relationship between the etching depth distribution and the opening and closing state of the vent. The generation of the control command is based on the process model and combines feedforward control and closed-loop feedback control.

8. The controllable non-uniform ceramic plate gas outlet system according to claim 7, characterized in that, The process model is a neural network model trained based on machine learning algorithms. Its inputs include historical etching depth data, current process parameters, and vent status, and its output is optimized vent control commands.

9. The controllable non-uniform ceramic plate gas outlet system according to any one of claims 1-8, characterized in that, The detection module is an interference endpoint detection device, which includes a broadband light source, a beam splitter, a reference mirror and a spectrometer. The interference endpoint detection device measures the wafer surface through an optical window set at the top of the process chamber and calculates the etching depth by analyzing the interference spectrum of the reflected light and the reference light. And / or, the vent holes are non-uniformly distributed on the lower surface of the ceramic substrate, with a higher vent hole density and / or a larger vent hole diameter in areas where the expected etching rate is slower; And / or, the controllable non-uniform ceramic plate gas outlet system further includes a pressure sensor array, which is disposed in each of the gas flow channel partitions to monitor the real-time pressure of each partition. The control unit is also configured to adjust the vent opening and closing actuator and / or the intake valve according to the monitored pressure data to achieve coordinated control of flow rate and pressure.

10. A gas flow control method based on the system described in any one of claims 1-9, characterized in that, include: The etching depth distribution on the wafer surface is monitored in real time using a detection module. Based on the etching depth distribution, determine whether the etching uniformity deviates from expectations; If the deviation from the expected behavior is detected, the vent opening and closing actuator is controlled to adjust the vent opening and closing status, thereby changing the gas flow rate of the vent in the corresponding area, thus correcting the spatial distribution of the reacting gas in the chamber and improving the uniformity of plasma density.

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