KR20240033001A - Upstream process monitoring of deposition and etch chambers - Google Patents

Abstract

A semiconductor manufacturing system includes a mixing bowl, a distribution system receiving a gas mixture from the mixing bowl, and a process chamber in fluid communication with the distribution system to perform 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 indicative of the type and flow rate of gas being detected. Additionally, at least one process chamber sensor is provided within the process chamber and disposed proximate to the substrate. The process chamber sensor has resonance characteristics that change upon exposure to the semiconductor process, i.e. upon accumulation of material deposited on the surface of the sensor, and produces material process signals indicative of the expected material on the surface of the substrate. issue.

Description

Upstream process monitoring of deposition and etch chambers

Cross-reference to related applications

Pursuant to Section 119 of the U.S. Patent Act and the relevant portions of Detailed Enforcement Rule No. 1.53, this application claims the benefit and priority of U.S. Patent Application No. 63/219,032, filed on July 7, 2021, and the entire contents of said U.S. Patent Application are This is supplemented by quotation.

BACKGROUND Deposition and etch processes in semiconductor manufacturing plants are widely and commonly used during device manufacturing in the semiconductor integrated circuit (IC) industry. The semiconductor industry's efforts to reduce dimensions, traditionally limited by the lithography resolution of two-dimensional structures, are shifting to controlling the deposition and etch processes of three-dimensional structures (e.g., 3D gates and 3D NAND). Gas mixtures containing two or more gas types are often used throughout sequences of deposition and etch processes and in pre- and post-steps of the main sequence. Moreover, the critical dimensions of the device are increasingly influenced by the ability to control deposition and etch processes.

Plasma etch processes are often used to remove dielectrics, semiconductors or metal layers by igniting gas in a plasma state (which drives the activation energy of the chemical reaction). Removal of such material can also be performed by flowing a reactive gas (in a non-plasma state) or through wet etch stations (in a liquid state). Depositing films on chamber components and treated substrates can be performed using plasma enhanced (PE), chemical vapor deposition (CVD), sub-atmospheric CVD, or thermal. It can be applied by various methods such as CVD, atomic layer deposition (ALD), plasma enhanced atomic layer deposition, etc. Etching and deposition processes can be isotropic or anisotropic (such as reactive ion etching - RIE) depending on the process step.

In substrate deposition processes, such as IC manufacturing processes, depositing several different layers on a wafer (substrate) can be achieved through various reactions and various process material states. Representative technologies include plasma (PECVD and high density plasma (HDP)), gas-subatmospheric CVD (SACVD), and liquid (electroplating). Some of the key parameters that control deposited layers and device fabrication characteristics are thickness, stress, mass, resistivity, grain, and refractive index. These parameters are measured and controlled for average values (for a wafer or wafer batch) as well as for wafer variability and interstitial wafer variability. Reducing process variability contributes to improving manufacturing yield in end of line (EOL) processes.

For example, the following steps are used to etch a substrate: a wafer etching step (in conjunction with a lithography step) to apply a pattern to the fabricated device; cleaning the wafer from contamination; creating a trench between the transistors; enabling separation between the contact and the insulator; reacting the wafer surface prior to deposition and removing the photoresist. The key parameters that control the etch process on a wafer are etch rate, thickness, stress, critical dimensions for defined characteristics such as particle and defect control, and other electrical and optical parameters.

Substrate etch and deposition may or may not be simultaneous processes in the same process chamber, sequentially in the chamber, non-sequentially in the chamber, or in different chambers (e.g., in some of the HDP processes). Etching and deposition can occur sequentially or simultaneously).

Some of the known methods for monitoring processes using integrated sensors include mass spectrometers, optical analyzers, RF sensors and vacuum gauges. However, these methods are not localized and do not provide specific information about the film accumulated or removed at different chamber locations. Examples of non-localized process control include plasma cleaning methods such as optical emission spectrometry, residual gas analyzers, and chamber impedance measurements. However, all of these methods fail to identify complex signals from the entire chamber and the uniformity or homogeneity of process materials at different chamber locations. Other known sensors, such as temperature sensors, can localize and read measurements along the surfaces of various chamber components but do not provide specific information about film conditions related to the coating of these surfaces.

Current solutions for monitoring problems related to gas mixing or flow timing are in the process chamber and exhaust lines. Once a process defect (the “wrong” gas mixture) reaches the process chamber or chamber exhaust, it is already too late and damage to the material has already occurred.

U.S. Patent Application Publication No. 2012/0201954 (Wajid) discloses a QCM that employs a single location that provides information about film coating or etching but does not provide information about uniformity or homogeneity of the process at different chamber locations. there is. Here, as the size of the chamber increases, the accuracy and value of the process data decreases.

US Patent Application Publication No. 2014/0053779 (Martinson et al.) describes a QCM probe that moves between different chamber positions. However, this solution is limited to research labs and is only compatible with manufacturing environments that require vacuum for manufacturing. Additionally, this solution does not facilitate simultaneous monitoring of QCM sensors at different chamber locations.

Therefore, there is a need to (i) identify incorrect or unbalanced gas mixtures and (ii) control the timing of deposition and etch tools to allow for tighter process control during deposition and etch processes.

A semiconductor manufacturing system includes a mixing bowl, a distribution system receiving a gas mixture from the mixing bowl, and a process chamber in fluid communication with the distribution system to perform several semiconductor processes, such as deposition and etching processes, on a substrate. Includes. A plurality of mixing bowl sensors are disposed within a cavity of the mixing bowl and emit gas signals indicative of the type and flow-rate of the gas being detected. Additionally, at least one process chamber sensor is provided within the process chamber and disposed proximate to the substrate. The process chamber sensor has resonance characteristics that change upon exposure to a semiconductor process, i.e. upon accumulation of material deposited on the surface of the sensor, and issues material process signals indicative of the expected material on the surface of the substrate. do. A controller is responsive to gas and material process signals to control the gas mixing in the mixing bowl and the material projected onto the substrate surface.

In another embodiment, a method for monitoring a semiconductor process is provided. The method includes the steps of (i) disposing a plurality of mixing bowl sensors within a cavity of the mixing bowl to detect at least one gas of a gaseous material and issuing a gas signal indicative of the gas being detected; (ii) distributing the flow of gaseous material into the semiconductor process chamber by a distribution system; (iii) supporting a substrate in the semiconductor process chamber and a process chamber sensor proximate the substrate, the process chamber sensor comprising depositing on a detection surface of the process chamber sensor to correlate deposition and etch processes on the surface of the substrate. and detecting etch processes, and (iv) controlling the flow of gases entering the mixing bowl and semiconductor processes performed in the process chamber to optimize fabrication of a semiconductor circuit.

The above embodiments are merely examples. Other embodiments as described herein are within the scope of the disclosed subject matter.

In order that the features of the present disclosure may be understood, some embodiments may be described in detail with reference to specific embodiments shown in the accompanying drawings. However, it should be noted that the accompanying drawings only illustrate specific embodiments and should not be considered to limit the scope of the present disclosure since the scope of the disclosed subject matter includes other embodiments as well. The accompanying drawings are not necessarily to scale and are generally focused on showing features of specific embodiments. In the accompanying drawings, similar symbols are used to indicate similar parts throughout the various drawings.

1 is a perspective view of a semiconductor manufacturing system including a mixing bowl, dispensing system, and process chamber.
FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1.
FIG. 3 is a cross-sectional view substantially taken along line 3-3 of FIG. 2 along a plane perpendicular to the vertical axis defined by the mixing bowl and the process chamber.
4 is a perspective view of another embodiment of a semiconductor manufacturing system where the distribution system includes a plurality of conduits where at least one conduit distributes gas directly to a process chamber.
5 shows another embodiment of a semiconductor manufacturing system where mixing bowl sensors include a plurality of Quartz Crystal Microbalance (QCM) sensors and a plurality of optical/mass spectrometers and a distribution system guides the gas mixture to a plurality of process chambers. It is a perspective view.
These reference characters represent the corresponding parts throughout the various drawings. The examples presented herein illustrate various embodiments but should not be construed as limiting the scope in any way.

This disclosure relates to the field of semiconductor manufacturing, including semiconductor manufacturing control. More specifically, in one example, a semiconductor manufacturing system monitors semiconductor manufacturing processes using sensors located at strategic upstream and downstream locations, namely the upstream mixing bowl and the downstream process chamber to ensure accuracy and homogeneity of deposition and etch processes. Increase. For example, a unique method is disclosed herein for monitoring a gas mixture at an upstream location within the mixing bowl prior to distribution by sprinkler heads and upstream of a process chamber. Placing sensors in both upstream and downstream locations facilitates measurement of several material properties (mass density and stress) due to the non-homogeneity of the process within the upstream mixing bowl and downstream process chamber.

1, 2, and 3, a schematic perspective and cross-sectional view of the manufacturing system 10 includes a mixing bowl 12, a dispensing system 16 in fluid communication with the mixing bowl 12, and the dispensing system 16. and a process chamber 20 in fluid communication with system 16. The mixing bowl (16) receives a gas mixture from several external gas sources (18) and includes a plurality of gas sensors (22) disposed within the cavity (24) defined by the mixing bowl (16). . The gas sensors 22 will be described in more detail below, but at this point it will only be assumed that the gas sensors 22 detect at least one gas of the gas mixture and issue gas signals along lines 26. Suffice it to say. The gas sensors 22 may be distributed uniformly within the mixing bowl cavity 24, but preferably in close proximity to each opening of the mixing bowl cavity, i.e. through the side or cylindrical cavity wall 28. is located (best shown in Figure 3). The openings are in fluid communication with a plurality of radiating pipes or conduits 30 of the distribution system 16 , which in turn distribute the gas mixture to several sprinkler heads 34 located above the process chamber 20 . The distribution system 16 may include a plurality of conduits 30 in fluid communication with the mixing bowl 12 at one end and one or more sprinkler heads 34 at the other end. Alternatively, the distribution system 16 may include one or more conduits 30 with each conduit leading directly to a dedicated process chamber 20. This embodiment is shown in Figure 4 of this disclosure.

Many different types of sensors may be employed with the present disclosure. For example, Quartz Crystal Microbalance (QCM) sensors or Microelectromechanical (MEM) sensors may be deployed. Quartz Crystal Microbalance (QCM) sensors 22 within the mixing bowl 16 augment the deposition and etch processes performed in the process chamber 20 . A QCM sensor 22 placed near the zone or area to be monitored can assume that changes to the surface of the QCM can be correlated to the same process performed on the surface of the substrate 36 and thus to the semiconductor process. Provides information about In one embodiment, the QCM sensor 22 has resonance characteristics that change upon exposure to the semiconductor processes. Changes in mass change the resonance response of the QCM crystal, which is indicative of the expected changes occurring on the substrate 36. Although the process chamber 20 and the process chamber sensors 42 will be discussed in the following paragraphs, the same or similar indications may be assumed for the semiconductor manufacturing process within the process chamber 20. In one embodiment of the present disclosure, the QCM sensors 22, 42 monitor local process conditions by monitoring process conditions such as temperature, flow, pressure, etc. at known thickness and stress accumulation. Instead of QCM sensors, MEM sensors can be used in the same way.

One example of a MEM sensor for use in the present disclosure is a surface acoustic wave sensor. Those skilled in the art will easily understand how QCM and MEM sensors are made and used. The present disclosure uses a variety of such sensors placed at various locations within the mixing bowl 16 to identify the type, temperature, flow rate, concentration, etc. of the gas detected.

Combinations of any of the following sensor types may be used as a sensor in one or more embodiments: capacitor sensors, photocathodes, photodetector sensors, micromachined ultrasonic transducers, energy or Oscillator devices configured to measure mass changes, resonant electrical/optical devices, sensors for measuring resistance, sensors having a dielectric waveguide in contact with a metal layer or metal pattern suitable for generating a plasmonic reaction, light emission. Devices, electron beam sources, ultrasonic sources, optical resonators, micro-ring resonators, photonic crystal structure resonators, temperature sensors.

By using QCM sensors both at an upstream location within the mixing bowl 16 and at a downstream location within the process chamber 20, critical information can be obtained that reflects real-time process homogeneity within the chamber and occurs on the substrate 36. You can.

A measure of process homogeneity can be made by measuring the QCM frequency values starting from the beginning of the deposition sequence (for a given manufacturing recipe) and ending with the plasma clean sequence. Additionally, the difference in frequency, or delta, of start and end between different runs provides important information about process stability at a particular location.

Another example of a process homogeneity measurement relates to the difference in frequency of wafer deposition start and end between multiple wafers (for the same recipe). At this time, specific correlation parameters or equations (based on QCM location) can be calculated to predict wafer thickness and thickness variability. This may help avoid using test wafers for thickness measurements, and can be used as feedforward or backward information to control several 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 taking the peak frequency during the plasma clean at several QCM locations, which allows the user to know whether the film is accumulating as under-etched or over-etched at a particular location. The algorithm for determining the process end point can use frequency information from multiple QCM sensors distributed at multiple locations and can be used to optimize the process end point (EP) of cleaning. For example, you can monitor the moving average of the frequency derivative until it reaches a threshold, which means the frequency derivative becomes much lower when the end point of cleaning is reached. For example, over-etching or under-etching of several components may be intentionally achieved, or over-etching or under-etching of several components may be intentionally achieved. The same or similar techniques can be applied to other time-based processes using addition or removal of materials such as undercoating, precoating, etc.

Endpoint detection of wafer-based processes such as deposition, etch, densification and decontamination using plasma or heat (pretreatment or bake out) can also be accomplished using multiple QCM sensors distributed at multiple locations. It can be realized using signal inputs from (22, 42). QCM sensors 22, 42 distributed at various locations within the mixing bowl 16 and process chamber 20 can measure various deposition and etch rates to provide information regarding process uniformity.

Additionally, at least two QCM sensors (with respect to the plane of the substrate 36) each having a different angular orientation (with respect to the plane of the substrate 36) at each location, that is, at each location within the mixing bowl 16 and the process chamber 20. By implementing 22, 42), the process speed can be measured and/or calculated at different angles across the substrate 36 to provide three-dimensional information about the process and process speed in the substrate plane.

The gas mixture is distributed at various locations within the process chamber 20, and in the embodiment shown in FIGS. 1, 2, and 3, the gas mixture enters the process chamber 20 at four locations or enters the process chamber 20. It enters each of my four quadrants. As mentioned above, process chamber sensors 42 are located at various locations within the process chamber 20 and emit material process signals indicative of semiconductor processing occurring at these locations.

In other embodiments shown in FIGS. 4 and 5, the mixing bowl 12 may supply a plurality of process chambers 20. Instead of a single mixing bowl 12 being dedicated to a process chamber 20 , the mixing bowl 16 may be fed directly to multiple process chambers 20 . 5, the mixing bowl 16 includes a combination of QCM sensors 22 and optical/mass spectrometers 52 to provide additional information at a location upstream of the process chamber 20. The QCM sensors are placed on the internal periphery of the mixing bowl 16 while the optical/mass spectrometers are placed along the top surface or surface of the mixing bowl 16.

Controller 50 controls (i) gas signals 26 issued by the gas sensors 22 in the mixing bowl 16, and (ii) the process chamber sensors in the process chamber 20. Controls the mixture of gaseous materials in both the mixing bowl 20 and the process chamber 20 in response to material process signals 46 issued by 42. A closed-loop feedback loop determines the mix, flow, and concentration of the gas mixture entering the process chamber 20 in an effort to predict material deposited on or removed from the surface of the substrate 36. Can be used to control.

In summary, the semiconductor manufacturing system 10 of the present disclosure provides information about the gas mixture well ahead of the process chamber 20 or in the exhaust line (not shown). In some cases, it may already be too late to correct the defect. Additionally, the present disclosure provides a semiconductor manufacturing system and method that facilitates detection of incorrect gas mixtures and/or timing problems associated therewith (e.g., due to malfunctioning gas valves) in a process chamber of a semiconductor manufacturing apparatus. Mixing bowl sensors (i.e., QCM or mass spectrometer sensors) are positioned at the inlet of the mixing bowl 12, inside the mixing bowl 12, or from the mixing bowl 12 to the sprinkler heads 34. ) or may be located in the exhaust conduit 30 leading to the process chamber 20.

Accordingly, the semiconductor manufacturing system 10 of the present disclosure provides information about the gas mixture well in advance of the process chamber 20 or in the exhaust line (not shown). It may already be too late to correct the defect. In addition to gas mixtures, the semiconductor manufacturing system and method facilitates identification of atmospheric or internal leaks in gas supply lines. For example, O2 and SiH4 can react exothermically, and these exothermic reactions can result in particulate contamination. The semiconductor manufacturing system 10 of the present disclosure can detect this reaction upstream of the mixing bowl 12 to prevent damage to the system. In the same way, the QCM sensors 22 can detect solid state or particulate contamination of fabricated wafers.

Additional embodiments include any one of the embodiments described above, wherein one or more of the components, functions, or structures of the embodiment are equivalent to components, functions, or structures of a different embodiment described above. Interchangeable with, substituted for, or augmented with one or more of the following:

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 the disclosure and without diminishing the intended advantages of the disclosure. Accordingly, such changes and modifications are intended to be encompassed by the appended claims.

Although several embodiments of the present disclosure have been disclosed in the foregoing specification, those skilled in the art will be able to make many modifications to the present disclosure in connection with the present disclosure while having the benefit of the teachings presented in the foregoing description and associated drawings. and other embodiments that come to mind. Accordingly, it is to be understood herein that the present disclosure is not limited to the specific embodiments disclosed above, but that many modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although specific terms are employed herein as well as in the claims below, such specific terms are used in a general and descriptive sense only and are not used for the purpose of limiting the disclosure or the scope of the claims below. no.

Claims (14)

As a semiconductor manufacturing system,
The semiconductor manufacturing system is,
a mixing bowl defining a cavity for receiving the gaseous material mixture used to perform semiconductor processes on the substrate;
a plurality of mixing bowl sensors disposed within the cavity of the mixing bowl for detecting at least one gas of the gaseous material mixture, each of the plurality of mixing bowl sensors emitting a gas signal indicative of the gas being detected;
a material distribution system for receiving gaseous material from the mixing bowl and distributing the gaseous material within the process chamber;
A process chamber for receiving a substrate and at least one process chamber sensor proximate the surface of the substrate, wherein the process chamber receives the gaseous material mixture from the mixing bowl and is positioned at the surface of the substrate while the at least one process chamber sensor is present. in fluid communication with the material distribution system to perform semiconductor processes thereon, wherein the process chamber sensor has resonant characteristics that change upon exposure to the semiconductor processes, wherein the process chamber sensor detects the material expected on the surface of the substrate. Issues a material process signal indicating -; and
a controller to control the gaseous material mixture in the mixing bowl and the material expected on the substrate in response to the gas and material process signals;
A semiconductor manufacturing system including. According to paragraph 1,
and the distribution system includes a plurality of sprinkler heads for distributing the flow of gaseous material mixture to the process chamber. According to paragraph 1,
and the distribution system includes at least one conduit for delivering a flow of the gaseous material mixture directly to the process chamber. According to paragraph 1,
wherein the distribution system includes a plurality of conduits, each of the plurality of conduits distributing a flow of the gaseous material mixture to the process chamber. According to paragraph 1,
The mixing bowl sensor includes a group of sensors consisting of a quartz crystal microbalance (QCM), an optical, and a mass spectrometer sensor. According to paragraph 1,
The semiconductor manufacturing system of claim 1, wherein the material process chamber sensors include a group of sensors consisting of Quartz Crystal Microbalance (QCM) and MicroElectroMechanical (MEM) sensors. According to paragraph 2,
The mixing bowl defines a circular planform having a plurality of cavity wall openings, and a mixing bowl sensor is disposed proximate to each cavity wall opening to detect gaseous material flowing from the mixing bowl to a selected one of the sprinkler heads. A semiconductor manufacturing system that detects. According to clause 5,
The mixing bowl defines an opening in the cavity wall to facilitate flow of gaseous material to each conduit, and at least one mixing bowl of the plurality of mixing bowl sensors is disposed proximate to the cavity wall opening to detect the mixing bowl. A semiconductor manufacturing system for detecting gaseous material flowing from to a selected one of the sprinkler heads. According to clause 5,
The mixing bowl defines a cavity for receiving the gaseous material mixture, wherein at least one mixing bowl sensor of the plurality of mixing bowl sensors is disposed along an upper surface of the cavity to detect gaseous material flowing from the mixing bowl. semiconductor manufacturing system. According to paragraph 1,
The mixing bowl defines a cavity for receiving the gas material mixture, at least one mixing bowl sensor of the plurality of mixing bowl sensors is a quartz crystal microbalance (QCM) disposed along an inner peripheral surface of the cavity, and the plurality of mixing bowl sensors At least one other of the mixing bowl sensors is a mass spectrometer sensor and is disposed along an upper surface of the cavity to detect gaseous material flowing from the mixing bowl. According to paragraph 1,
The semiconductor manufacturing system is,
a plurality of process chamber sensors;
wherein each process chamber sensor is proximate to a surface of the substrate, and material process signals are adjusted to the distance and orientation of the process chamber sensors relative to the substrate to enhance correlation data between the substrate and the process chamber sensor. Depending on the semiconductor manufacturing system. A method of monitoring a semiconductor manufacturing process in a semiconductor process chamber receiving a gas mixture from a gas distribution system, the gas distribution system comprising a plurality of sprinkler heads in fluid communication with the semiconductor process chamber at a downstream end and a mixing bowl at an upstream end. A method for monitoring a semiconductor manufacturing process having a plurality of conduits in fluid communication with
disposing a plurality of mixing bowl sensors within a cavity of the mixing bowl to detect at least one gas of a gaseous material and issuing a gas signal indicative of the gas being detected;
distributing a flow of gaseous material into the semiconductor process chamber through sprinkler heads of the gas distribution system;
supporting a substrate in the semiconductor process chamber and a process chamber sensor proximate the substrate, the process chamber sensor detecting deposition and etch processes on a detection surface of the process chamber sensor;
Including, a method for monitoring a semiconductor manufacturing process. According to clause 8,
The resonance characteristics of the process chamber sensor change upon exposure to the semiconductor process and upon accumulation of deposited material on the detection surface of the process chamber sensor, the method comprising:
issuing a material process signal indicative of expected material on the surface of the substrate;
A method for monitoring a semiconductor manufacturing process, further comprising: According to clause 8,
The monitoring method of the semiconductor manufacturing process is,
Disposing a plurality of sensors in a process chamber to measure material process data occurring in proximity to each of the plurality of sensors;
It further includes,
A first sensor defines a first spatial position within the process chamber and a second sensor defines a second spatial position within the process chamber, the first spatial position having a different angular orientation than the second spatial position. Monitoring method of semiconductor manufacturing process.