Upstream process monitoring for deposition and etch chambers

Abstract

A semiconductor manufacturing system includes: a mixing bowl, a distribution system for receiving a gas mixture from the mixing bowl, and a process chamber in fluid communication with the distribution system for performing various semiconductor processes, such as deposition and etching processes, on a substrate. A plurality of mixing bowl sensors are disposed within the cavity of the mixing bowl and emit gas signals indicating the type and flow rate of the detected gas. Furthermore, at least one process chamber sensor is provided within the process chamber and disposed proximal to the substrate. The process chamber sensor has resonant properties that change upon exposure to a semiconductor process (i.e., accumulation of deposited material on the surface of the sensor) and emits a material process signal indicating the expected material on the surface of the substrate.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing, and in particular to semiconductor manufacturing systems and methods for monitoring semiconductor processes. Cross-references to related applications This application is a provisional patent application filed pursuant to the relevant parts of 35 USC 111 and 37 CFR 1.53. Prior Technology

[0002] Deposition and etching processes in semiconductor manufacturing plants are widely and universally used during device fabrication in the semiconductor integrated circuit (IC) industry. The semiconductor industry's efforts to reduce size—traditionally limited by the lithographic resolution of two-dimensional structures—are shifting towards controlled deposition and etching processes for three-dimensional structures, such as 3D gates and 3D NAND. Often, gas mixtures containing more than one gas type are used in the sequence of deposition and etching processes, as well as in the preceding and subsequent steps of the main sequence. Furthermore, the critical dimensions of devices are increasingly influenced by the ability to control the deposition and etching processes. Plasma etching processes are commonly used to remove dielectric, semiconductor, or metal layers using ignition gases in a plasma state (which drive the activation energy of chemical reactions). Material removal can also be performed by flowing reactive gases (in a non-plasma state) or by wet etching (in a liquid state) stations. Thin film deposition can be applied to chamber components and treated substrates using various methods, such as plasma-enhanced (PE) chemical vapor deposition (CVD), subatmospheric pressure CVD, thermal CVD, atomic layer deposition (ALD), plasma-enhanced atomic layer deposition, etc. Depending on the process steps, etching and deposition processes can be isotropic or anisotropic (e.g., reactive ion etching - RIE). In substrate deposition processes (such as IC manufacturing), many different layers can be deposited on a wafer (which is the substrate) through different reactions and different process material states. Example technologies include plasma (PECVD and high-density plasma-HDP), gas-sub-atmospheric pressure CVD (SACVD), and liquid (electroplating). Some examples of key parameters used to control the characteristics of deposited layers and device fabrication are: thickness, stress, mass, resistivity, grain size, and refractive index. These parameters are measured and controlled not only for average values ​​(on a wafer or a batch of wafers) but also for wafer variability and inter-wafer variability. Reducing process variability contributes to improved manufacturing yield at end-of-line (EOL) processes. For example, substrate etching uses the following steps: a wafer etching step to apply a pattern (combined with a photolithography step) to the fabricated device; cleaning the wafer to prevent contamination; creating trenches between transistors; achieving separation between contacts and insulators; and reacting the wafer surface before deposition and to remove photoresist. Key parameters used to control the etching process on the wafer include: critical dimensions of the defined features, such as etching rate, thickness, stress, particle and defect control, and other electrical and optical parameters. Substrate etching and deposition may or may not be simultaneous processes in the same process chamber (e.g., in some HDP processes, etching and deposition may occur sequentially or simultaneously), performed continuously in the chamber, or performed non-sequentially in the chamber or in different chambers. Some known methods for process monitoring using integrated sensors include mass spectrometry, optical spectrometry, RF sensors, and vacuum gauges. However, these methods are not localized and fail to provide detailed information about the thin films accumulated or removed at different chamber locations. An example of nonlocalized process control includes plasma cleaning methods such as optical emission spectroscopy, residual gas analyzers, and chamber impedance measurements. However, all of these methods measure cyclotron signals from the entire chamber and do not identify the homogeneity or uniformity of the process material at different chamber locations. Other known sensors, such as temperature sensors, can locate and read measurements along the surfaces of various chamber components, but will not provide detailed information about the condition of the thin films associated with coating these surfaces. Current solutions for monitoring gas mixtures or flow timing problems are located in the process chamber and exhaust line. By the time a process fault ("wrong" gas mixture) reaches the process chamber or exhaust, it is too late, and damage to the materials has already occurred. U.S. Patent Application Publication No. 2012 / 0201954 (Wajid) discloses a QCM that provides information about thin film coating or etching, but uses a single location, which fails to provide information about the uniformity or homogeneity of the process at different chamber locations. Furthermore, the accuracy and values ​​of the process data decrease with increasing chamber size. U.S. Patent Application Publication No. 2014 / 0053779 (Martinson et al.) describes a QCM probe that moves between different chamber locations. However, this solution is limited to research laboratories and is only compatible with production environments where a vacuum is required for production. Furthermore, this solution does not facilitate simultaneous monitoring of QCM sensors at different chamber locations. Therefore, there is a need for: (i) identifying incorrect or disproportionate gas mixtures and (ii) controlling the timing of deposition and etching tools to allow for more stringent process control during the deposition and etching process. Summary of the Invention

[0003] A semiconductor manufacturing system includes: a mixing bowl, a distribution system for receiving a gas mixture from the mixing bowl, and a process chamber in fluid communication with the distribution system for performing various semiconductor processes, such as deposition and etching processes, on a substrate. A plurality of mixing bowl sensors are disposed within the cavity of the mixing bowl and emit gas signals indicating the type and flow rate of the detected gas. Furthermore, at least one process chamber sensor is provided within the process chamber and disposed proximal to the substrate. The process chamber sensor has resonant properties that change upon exposure to a semiconductor process (i.e., accumulation of deposited material on the surface of the sensor) and emits a material process signal indicating the desired material on the surface of the substrate. A controller responds to the gas and material process signals to control the mixing of the gas in the mixing bowl and the desired material on the surface of the substrate. In another embodiment, a method for monitoring a semiconductor process is provided. The method includes the steps of: (i) placing a plurality of mixing bowl sensors within the cavity of a mixing bowl to detect at least one gas of a gaseous material and emitting a gas signal indicating the detected gas; (ii) distributing a flow of gaseous material into a semiconductor process chamber by a dispensing system; (iii) supporting a substrate within the semiconductor process chamber and a process chamber sensor proximal to the substrate, the process chamber sensor detecting deposition and etching processes on its detection surface to correlate the deposition and etching processes on the surface of the substrate; and (iv) controlling the gas flow into the mixing bowl and the semiconductor processes performed within the process chamber to optimize the fabrication of the semiconductor circuit. The above embodiments are merely exemplary. Other embodiments described herein are within the scope of the disclosed subject matter. Simple Explanation of the Diagram

[0004] To enable the understanding of the features of this disclosure, reference can be made to certain embodiments for detailed description, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only certain embodiments and should not be construed as limiting their scope, as the scope of the disclosed subject matter also covers other embodiments. The drawings are not necessarily to scale, and the emphasis is generally placed on illustrating the features of certain embodiments. In the drawings, similar numerals are used throughout the various views to indicate similar portions, wherein: [Figure 1] is a perspective view of a semiconductor manufacturing system including a mixing bowl, a dispensing system, and process chambers; [Figure 2] is a cross-sectional view taken essentially along line 2-2 of Figure 1; and [Figure 3] is a cross-sectional view taken substantially along line 3-3 of Figure 2, along a plane orthogonal to the vertical axis defined by the mixing bowl and the process chamber. [Figure 4] is a perspective view of another embodiment of a semiconductor manufacturing system, wherein the distribution system includes a plurality of conduits, wherein at least one of the conduits directly distributes gas to a process chamber. [Figure 5] is a perspective view of another embodiment of a semiconductor manufacturing system, wherein the mixing bowl sensor includes multiple quartz crystal microbalance (QCM) sensors and multiple optical spectrometers / mass spectrometers, and wherein a dispensing system guides the gas mixture into multiple process chambers. The corresponding reference characters pertain to several view indicators of the corresponding portions. The examples described herein illustrate several embodiments, but should not be construed as limiting the scope in any way. Implementation

[0005] This disclosure relates to the field of semiconductor manufacturing, including semiconductor manufacturing control. More specifically, in one example, the semiconductor manufacturing system employs sensors located at upstream and downstream positions in the strategy (i.e., in the upstream mixing bowl and the downstream process chamber) to monitor the semiconductor manufacturing process to enhance the accuracy and homogeneity of the deposition and etching processes. For example, a unique method is disclosed herein for monitoring the gas mixture at an upstream position within the mixing bowl, prior to dispensing through the sprayer head and upstream of the process chamber. Advantageously, due to the heterogeneity of the process within both the upstream mixing bowl and the downstream process chamber, deploying sensors at both upstream and downstream positions facilitates the measurement of different material properties (mass density and stress). In Figures 1, 2, and 3, schematic perspective and cross-sectional views of the manufacturing system 10 include a mixing bowl 12, a distribution system 16 in fluid communication with the mixing bowl 12, and a process chamber 20 in fluid communication with the distribution system 16. The mixing bowl 16 receives a gas mixture from several external gas supply sources 18 and includes a plurality of gas sensors 22 disposed within a cavity 24 defined by the mixing bowl 16. The gas sensors 22 are described more fully below, but for this particular moment it will be said that the gas sensors 22 detect at least one gas in the gaseous mixture and emit a gas signal along line 26. The gas sensors 22 may be uniformly distributed within the mixing bowl cavity 24; however, they are preferably located near each opening of the mixing bowl cavity, i.e., through the transverse or cylindrical cavity wall 28 (best seen in Figure 3). The openings are in fluid communication with a plurality of radial tubes or conduits 30 of the distribution system 16, which in turn distributes the gaseous mixture to a plurality of sprayer heads 34 located above the process chamber 20. The dispensing system 16 may include a plurality of conduits 30 in fluid communication at one end with a mixing bowl 12 and at the other end with one or more sprayer heads 34. Alternatively, the dispensing system 16 may include one or more conduits 30, each leading directly to a dedicated process chamber 20. This embodiment is illustrated in Figure 4 of this disclosure. Many different types of sensors can be employed in this disclosure. For example, a quartz crystal microbalance (QCM) sensor or a microelectromechanical (MEMS) sensor can be deployed. The quartz crystal microbalance (QCM) sensor 22 in the mixing bowl 16 enhances the deposition and etching processes performed in the process chamber 20. The QCM sensor 22, placed near the area to be monitored, provides information about the semiconductor process because it can be assumed that changes to the QCM surface can be associated with the same processes performed on the surface of the substrate 36. In one embodiment, the QCM sensor 22 has resonant properties that change upon exposure to the semiconductor process. Changes in mass alter the resonant response of the QCM crystal, indicating the expected changes occurring on the substrate 36. As will be discussed in subsequent paragraphs regarding the process chamber 20 and the process chamber sensor 42, the same or similar indications can be assumed regarding the semiconductor fabrication process within the process chamber 20. In one embodiment of this disclosure, QCM sensors 22 and 42 monitor process conditions such as temperature, flow rate, pressure, etc., with known accumulations of thickness and stress to monitor localized process conditions. Instead of QCM sensors, MEM sensors can be used in the same way. An example of a MEM sensor used in this disclosure is a surface acoustic wave sensor. Those skilled in the art will readily understand how QCM and MEM sensors are manufactured and used. This disclosure utilizes a variety of such sensors positioned at different locations within the mixing bowl 16 to identify the type, temperature, flow rate, concentration, etc., of the detected gas. In one or more embodiments, any combination of the following sensor types can be used as a sensor: capacitor sensor, photocathode, photodetector sensor, microfabricated ultrasonic transducer, oscillator device configured to measure energy or mass changes, resonant electro / optical device, resistance measurement sensor, sensor having a dielectric waveguide in contact with a metal layer or metal pattern suitable for generating plasma reactions, light-emitting device, electron beam source, ultrasonic source, optical resonator, microring resonator, photonic crystal structure resonator, and temperature sensor. By using QCM sensors located both upstream within the mixing bowl 16 and downstream within the process chamber 20, important information reflecting the real-time process homogeneity within the chamber and what is occurring on the substrate 36 can be obtained. The results of process homogeneity measurements can be obtained by measuring the QCM frequency values ​​(for a given production formulation) that begin at the start of the deposition sequence and end with the plasma cleanup sequence. Furthermore, the differences or increments in the end-to-start frequencies between different runs provide crucial information about process stability at specific locations. Another example of process homogeneity measurement involves the frequency difference between the start and end of wafer deposition between different wafers (for the same recipe). Specific correlation parameters or equations (based on QCM location) can then be calculated to predict wafer thickness and thickness variability. This can help avoid using test wafers for thickness measurements, or can be used as feedforward or feedback information to control different process operations before or after substrate deposition. Instead of QCM sensors, MEM sensors can be used in the same way. Process homogeneity can also be measured by obtaining the maximum frequency during plasma cleaning from different QCM locations. This allows users to know whether the film accumulation at a particular location is due to under-etching or over-etching. Algorithms for determining the process endpoint can use frequency information from multiple QCM sensors distributed across different locations and can be used to optimize the process endpoint (EP) of cleaning. For example, a moving average of the frequency derivative can be monitored until a threshold is reached—that is, when the cleaning endpoint is reached, the frequency derivative becomes significantly lower. This over-etching or under-etching can be intentionally achieved or implemented for different sections, for example. The same or similar methods can be applied to other time-based processes using material addition or removal, such as primers, pre-coats, etc. Endpoint detection for wafer-based processes (such as deposition, etching, densification, and contaminant removal) using plasma or heating (pretreatment or baking) can also be achieved using signal inputs from multiple QCM sensors 22, 42 dispersed at different locations. The QCM sensors 22, 42 at different locations within the mixing bowl 16 and process chamber 20 can measure different deposition and etching rates to provide information about process uniformity. Furthermore, by implementing at least two QCM sensors 22, 42 at each location (i.e., in the mixing bowl 16 and the process chamber 20) with different angular orientations (relative to the plane of the substrate 36), the processing rate at different angles on the substrate 36 can be measured and / or calculated to provide three-dimensional information about the process and process rate in the substrate plane. The gaseous mixture is dispersed at multiple locations within the process chamber 20, and in the embodiments shown in Figures 1, 2, and 3, the gaseous mixture enters the process chamber at four (4) locations or in each of the four quadrants within the process chamber 20. As mentioned above, the process chamber sensor 42 is located at several locations within the process chamber 20 and emits material process signals indicating the semiconductor process occurring at these locations. In other embodiments depicted in Figures 4 and 5, the mixing bowl 12 can supply multiple process chambers 20. Instead of a single mixing bowl 12 dedicated to process chambers 20, the mixing bowl 16 can directly feed several process chambers 20. In Figure 5, the mixing bowl 16 includes a combination of a QCM sensor 22 and an optical spectrometer / mass spectrometer 52 to provide additional information about its location upstream of the process chambers 20. The QCM sensor is positioned relative to the inner periphery of the mixing bowl 16, while the optical spectrometer / mass spectrometer is positioned along its upper surface or surface. The controller 50 responds to (i) a gas signal 26 emitted by the gas sensor 22 within the mixing bowl 16, and (ii) a material process signal 46 emitted by the process chamber sensor 42 within the process chamber 20, to control the mixture of gaseous materials in both the mixing bowl 16 and the process chamber 20. A closed-loop feedback loop can be used to control the mixing, flow rate, and concentration of the gaseous mixture entering the process chamber 20, thereby controlling the amount of material to be deposited on or removed from the surface of the substrate 36. In summary, the semiconductor manufacturing system 10 of this disclosure provides information about gas mixtures that may be present long before the process chamber 20 or in the exhaust line (not shown), where it may be too late to correct defects. Furthermore, this disclosure provides a semiconductor manufacturing system and method thereof that facilitates the detection of incorrect gas mixtures in the process chamber of a semiconductor manufacturing apparatus and / or associated timing problems (e.g., due to gas valve malfunction). A mixing bowl sensor (i.e., a QCM or mass spectrometer sensor) may be located at the inlet of the mixing bowl 12, inside the mixing bowl 12, or in the exhaust conduit 30 leading from the mixing bowl 12 to the sprayer head 34 or directly to the process chamber 20. Therefore, the semiconductor manufacturing system 10 of this disclosure provides information about gas mixtures that are present long before the process chamber 20 or in the exhaust line (not shown), where it may be too late to correct defects. In addition to the gas mixture, this semiconductor manufacturing system and method also facilitates the identification of atmospheric or internal leaks in the gas supply line. For example, O2 and SiH4 can produce an exothermic reaction, which can lead to particulate contamination. The semiconductor manufacturing system 10 of this disclosure can detect this reaction upstream in the mixing bowl 12 to avoid damage to the system. In the same manner, the QCM sensor 22 is capable of detecting solid or particulate contamination of the production wafer. Other embodiments include any of the embodiments described above, wherein one or more of its components, functions, or structures are interchanged, replaced, or expanded with one or more of the components, functions, or structures of the different embodiments described above. It should be understood that various changes and modifications to the embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of this disclosure and without diminishing its intended advantages. Therefore, it is intended that such changes and modifications be covered by the appended claims. While several embodiments of this disclosure have been disclosed in the foregoing specification, those skilled in the art will understand that many modifications and other embodiments of this disclosure will arise from the teachings presented in the foregoing description and the associated drawings. Therefore, it is to be understood that this disclosure is not limited to the specific embodiments disclosed herein, and many modifications and other embodiments are intended to be included within the scope of the appended claims. Furthermore, while specific terms are used herein and in the following claims, they are used in a general and descriptive sense only and are not intended to limit this disclosure or the scope of the following claims.

[0006] 10: Manufacturing System 12: Mixing bowl 16: Distribution System 18: Gas supply source 20: Process Chamber 22: QCM sensor 24: Cavity 26: Gas Signal 28: Cavity wall 30: Catheter 34: Sprayer head 36: Substrate 42: Process Chamber Sensor 46: Material process signals 50: Controller 52: Optical Spectrometer / Mass Spectrometer

Claims

1. A semiconductor manufacturing system, comprising: A mixing bowl is defined as a cavity for receiving a gaseous mixture of materials used to perform semiconductor processes on a substrate; A plurality of mixing bowl sensors disposed within the cavity of the mixing bowl to detect at least one gas in the gaseous mixture of the material, the plurality of mixing bowl sensors emitting a gas signal indicating the detected gas; a material dispensing system for receiving gaseous material from the mixing bowl and dispensing the gaseous material within the process chamber; A process chamber for housing a substrate and at least one process chamber sensor proximal to the surface of the substrate, the process chamber being in fluid communication with the material dispensing system to receive a gaseous mixture of material from the mixing bowl, and performing a semiconductor process on the surface of the substrate in the presence of the at least one process chamber sensor, the process chamber sensor having resonant characteristics that change upon exposure to the semiconductor process, the process chamber sensor emitting a material process signal indicating a desired material on the surface of the substrate; And a controller that, in response to the gas and material process signals, controls the mixture of gaseous material in the mixing bowl and the desired material on the substrate.

2. The semiconductor manufacturing system of claim 1, wherein the material dispensing system includes a plurality of sprayer heads for dispensing a flow of the gaseous mixture into a process chamber.

3. The semiconductor manufacturing system of claim 1, wherein the material dispensing system includes at least one conduit for directly delivering a flow of the gaseous mixture to the process chamber.

4. The semiconductor manufacturing system of claim 1, wherein the material dispensing system includes a plurality of the conduits, each of the conduits dispensing a flow of the gaseous mixture to the process chamber.

5. The semiconductor manufacturing system of claim 1, wherein the plurality of mixing bowl sensors comprises sensors from the group consisting of: quartz crystal microbalance (QCM), optical and mass spectrometer sensors.

6. The semiconductor manufacturing system of claim 1, wherein the at least one process chamber sensor comprises sensors from the group consisting of quartz crystal microbalances (QCM) and microelectromechanical (MEM) sensors.

7. The semiconductor manufacturing system of claim 2, wherein the mixing bowl defines a circular planar shape having a plurality of cavity wall openings, and wherein a mixing bowl sensor is disposed near each cavity wall opening to detect gaseous material flowing out of the mixing bowl toward a selected one of the plurality of sprayer heads.

8. The semiconductor manufacturing system of claim 5, wherein the mixing bowl defines an opening in the cavity wall to facilitate the flow of gaseous material into each conduit, and wherein at least one of the plurality of mixing bowl sensors is disposed near the opening in the cavity wall to detect gaseous material flowing out of the mixing bowl toward a selected one of the plurality of sprayer heads.

9. The semiconductor manufacturing system of claim 5, wherein the mixing bowl defines a cavity for containing the gaseous mixture, and wherein at least one of the plurality of mixing bowl sensors is disposed along the upper surface of the cavity to detect gaseous material flowing out of the mixing bowl.

10. The semiconductor manufacturing system of claim 1, wherein the mixing bowl defines a cavity for containing the gaseous mixture, wherein at least one of the plurality of mixing bowl sensors is a quartz crystal microbalance (QCM) disposed along the inner peripheral surface of the cavity, and wherein at least another of the plurality of mixing bowl sensors is a mass spectrometer sensor disposed along the upper surface of the cavity to detect gaseous material flowing out of the mixing bowl.

11. The semiconductor manufacturing system of claim 1, further comprising a plurality of process chamber sensors, each process chamber sensor being proximal to the surface of the substrate, and wherein the material process signal is correlated according to the distance and orientation of the process chamber sensor relative to the substrate to enhance the correlation data between the substrate and the process chamber sensor.

12. A method for monitoring a semiconductor manufacturing process in a semiconductor process chamber receiving a mixture of gases from a gas distribution system, the gas distribution system having a plurality of spray heads in fluid communication with the semiconductor process chamber at a downstream end and a plurality of conduits in fluid communication with a mixing bowl at an upstream end, the method comprising the steps of: placing a plurality of mixing bowl sensors within a cavity of the mixing bowl to detect at least one gas of a gaseous material and emitting a gas signal indicating the detected gas; distributing a flow of gaseous material into the semiconductor process chamber through the plurality of spray heads of the gas distribution system; supporting a substrate within the semiconductor process chamber and a process chamber sensor proximal to the substrate, the process chamber sensor detecting deposition and etching processes on its detection surface to correlate the deposition and etching processes on the surface of the substrate.

13. The method of claim 12, wherein the resonant properties of the at least one process chamber sensor are altered upon exposure to the semiconductor process and accumulation of deposited material on the detection surface of the at least one process chamber sensor, and further comprises the step of: issuing a material process signal indicating a desired material on the surface of the substrate.

14. The method of claim 12, further comprising the steps of: placing a plurality of process chamber sensors within a process chamber to measure material process data occurring proximal to each of the plurality of process chamber sensors, a first process chamber sensor defining a first spatial position within the process chamber, and a second process chamber sensor defining a second spatial position within the process chamber, the first spatial position having an angular orientation different from the second spatial position.

15. The semiconductor manufacturing system of claim 1, wherein the process in the mixing bowl and the process chamber is heterogeneous.

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