Wafer sensor using quartz resonator capable of monitoring plasma process

Abstract

One embodiment of the present invention provides a wafer sensor using a quartz resonator and capable of monitoring a plasma process. A wafer-shaped sensor using a quartz resonator according to one embodiment of the present invention can be used to simultaneously measure frequency changes at various positions by attaching the quartz resonator on a wafer, and thus can improve production yield by diagnosing the degree of etching in real time during a plasma process. In addition, a wafer-shaped sensor using a quartz resonator according to one embodiment of the present invention can remove noise due to having a conductive layer formed on the surface of the quartz resonator, can be used for a long period of time, thus having an increased lifespan, and can reduce process costs through preventive maintenance (PM) cycle optimization.

Description

Wafer sensor utilizing a quartz crystal capable of monitoring plasma processes

[0001] The present invention relates to a wafer-type sensor utilizing a crystal oscillator capable of monitoring a plasma process, and more specifically, to a technology in which a wafer-type sensor (Sensor-on-Wafer) is positioned inside a chamber and changes in the process are measured in real time by measuring thickness changes and the degree of contamination during a plasma etching process.

[0002] Conventional wafer-type sensors (Sensor-on-Wafer, SoW) are used to diagnose various processes and have a shape similar to an actual wafer. While these wafer-type sensors can measure temperature, plasma density, and store data, they primarily measure various process variables (temperature, potential, current, thickness change, etc.), which presents a problem in that it is difficult to detect minute changes in the actual process.

[0003] Therefore, there are still many challenges remaining in developing SoW-type sensors capable of measuring minute thickness variations and contamination levels of deposited films as physical changes during the plasma process.

[0004] The technical problem to be solved by the present invention is to provide a wafer-shaped sensor using a crystal oscillator, and to provide a technology for measuring the degree of plasma etching and contamination through changes in the frequency of the crystal oscillator during a plasma process.

[0005] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0006] To achieve the above technical objectives, one embodiment of the present invention provides a wafer sensor utilizing a quartz crystal oscillator.

[0007] A wafer sensor utilizing a crystal oscillator according to one embodiment of the present invention may include: a wafer; a PCB module formed on the wafer; a crystal oscillator installed spaced apart on the PCB module; a silicon wafer formed on the upper portion of the crystal oscillator; and a conductive protective layer formed on the upper portion of the silicon wafer, the protective layer having pores formed on its surface.

[0008] In addition, according to one embodiment of the present invention, the wafer may include silicon or a conductive metal.

[0009] In addition, according to one embodiment of the present invention, the PCB module may include a CPU (central processing unit), a semiconductor device, or a battery power source.

[0010] In addition, according to one embodiment of the present invention, the crystal oscillator may include a crystal that is made of quartz and is a disk-shaped piezoelectric material; and an electrode layer made of metal and deposited on the upper and lower surfaces of the crystal.

[0011] In addition, according to one embodiment of the present invention, the diameter of the pores formed on the surface of the conductive protective layer may be 0.1 mm to 5 mm.

[0012] In addition, according to one embodiment of the present invention, the conductive protective layer may be a group of materials having conductivity, such as a metal or a metal compound.

[0013] In addition, according to one embodiment of the present invention, the total thickness of the wafer sensor utilizing the crystal oscillator may be 1 mm to 10 mm.

[0014] In addition, according to one embodiment of the present invention, the total mass of the wafer sensor utilizing the crystal oscillator may be 150g to 500g.

[0015] In addition, according to one embodiment of the present invention, the wafer sensor utilizing the crystal oscillator may be capable of wireless communication.

[0016]

[0017] To achieve the above technical objectives, another embodiment of the present invention provides a real-time monitoring system for a plasma etching process.

[0018] A real-time monitoring system for a plasma etching process according to one embodiment of the present invention may include: a plasma generating chamber that generates plasma light to etch a wafer or deposit a thin film on a wafer; a measuring unit that detects the thickness of the etched thin film and the degree of contamination of the plasma when the plasma process is operated by a wafer sensor utilizing a crystal oscillator of claim 1, installed on the upper part of an electrostatic chuck inside the plasma generating chamber; and a control unit located outside the plasma generating chamber that monitors the plasma process state by determining it as an abnormal process when the thickness of the etched thin film and the degree of contamination measured by the measuring unit differ from a preset reference value.

[0019] In addition, according to one embodiment of the present invention, the control unit can determine that the process is normal if the thickness and contamination level of the etched thin film measured by the measuring unit are the same as a preset reference value.

[0020] A wafer-shaped sensor utilizing a quartz crystal oscillator according to one embodiment of the present invention can simultaneously measure frequency changes at various locations by attaching a quartz crystal oscillator to a wafer, thereby enabling real-time diagnosis of the degree of etching during a plasma process and improving production yield.

[0021] In addition, a wafer-shaped sensor utilizing a quartz crystal oscillator according to one embodiment of the present invention can eliminate noise by forming a conductive layer on the surface of the quartz crystal oscillator, and the sensor can be used for a long period of time, thereby increasing the lifespan of the sensor and reducing process costs through the optimization of the preventive maintenance (PM) cycle.

[0022] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the invention or the claims.

[0023] FIG. 1 is a plan view of a wafer-shaped sensor utilizing a crystal oscillator of the present invention.

[0024] FIG. 2 is a front view of a wafer-shaped sensor utilizing a crystal oscillator of the present invention.

[0025] FIG. 3 is a front view showing the movement of ions during the plasma process of a wafer-shaped sensor utilizing a quartz crystal oscillator of the present invention.

[0026] The present invention will be described below with reference to the attached drawings. However, the present invention may be implemented in various different forms and is therefore not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0027] Throughout the specification, when it is stated that a part is "connected (connected, in contact, combined)" with another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members interposed between them. Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0028] The terms used herein are merely for describing specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0029]

[0030] Hereinafter, the present invention will be described with reference to the drawings presented in this specification. For reference, the drawings may be partially exaggerated to illustrate the features of the present invention. In such cases, it is preferable to interpret them in light of the entire intent of this specification.

[0031]

[0032] Referring to FIGS. 1 to 3, a wafer sensor utilizing a crystal oscillator according to one embodiment of the present invention will be described.

[0033] Referring to FIGS. 1 to 3, a wafer sensor utilizing a crystal oscillator according to one embodiment of the present invention is,

[0034] It may include a wafer (100); a PCB module (200) formed on the wafer; a crystal oscillator (300) installed on the PCB module at a predetermined interval; a silicon wafer formed on the upper part of the crystal oscillator; and a conductive layer (500) formed on the upper part of the crystal oscillator, having pores formed on its surface.

[0035] First, the present invention may include a wafer (100).

[0036] The present invention is characterized by a wafer-shaped sensor positioned inside a plasma chamber to measure thickness changes or the degree of contamination in real time during an etching process.

[0037] At this time, the wafer sensor of the present invention is not in an electrically separated state on the electrostatic chuck installed inside the plasma chamber, but exists in an electrically connected state, so that a potential difference can be intentionally applied.

[0038] At this time, the present invention can apply a specific voltage to a sensor or form a potential difference between the sensor and the plasma through an electrostatic chuck. This enables effects such as ion energy control and process optimization in the plasma process.

[0039] In addition, the wafer of the present invention may have a width of 300 mm and a length of 300 mm, and is not limited to the above-mentioned figures; it can be used without limitation in the case of a wafer in which etching is performed by performing a plasma etching process.

[0040]

[0041] In addition, the present invention may include a PCB module (200).

[0042] In this case, the PCB module of the present invention does not refer to a simple circuit board, but rather means a system designed as an independent electronic system.

[0043] At this time, the PCB module of the present invention is characterized by including a CPU (Central Processing Unit), a semiconductor device, or a battery power source, and the PCB module of the present invention is characterized by not only performing simple signal transmission but additionally including various devices to implement a functional electronic system in application fields such as data transmission and smartphones.

[0044] At this time, the PCB module of the present invention may be formed on a wafer and may be formed to cover the entire wafer, and a PCB module of the same or smaller size as the wafer used in the present invention may be used.

[0045]

[0046] In addition, the present invention may include a crystal oscillator (300).

[0047] At this time, the real-time monitoring sensor for the plasma etching process of the present invention is characterized by using the crystal oscillator, and the crystal oscillator is a device using quartz, which is a piezoelectric material that vibrates at a constant frequency, and since it can measure changes in the mass of a material adsorbed or deposited on a surface with great precision, it can be utilized to measure changes in the thickness of the etched layer in real time, especially in the plasma etching process.

[0048] At this time, the crystal oscillator of the present invention is characterized by comprising: a crystal, which is a disk-shaped piezoelectric material made of quartz; and an electrode layer made of metal, which is deposited on the upper and lower surfaces of the crystal.

[0049] At this time, the quartz crystal of the present invention is a disc-shaped piezoelectric material made of quartz, which can vibrate at a specific frequency depending on its thickness and surface characteristics, and is characterized by having a natural frequency of 5 MHz to 10 MHz in the present invention.

[0050] At this time, the reason the natural frequency is set to the aforementioned range is that the thickness of the material to be measured is in the range of several nm to several hundred μm, and this is a region where the frequency induced when the material is deposited on the surface of the quartz crystal is expected to change.

[0051] At this time, the wafer sensor utilizing the crystal oscillator of the present invention is manufactured to monitor a plasma etching process in real time, and is characterized by observing and measuring the state of the etched thin film or determining the degree of contamination during the etching process by monitoring the frequency of the crystal oscillator changing from 0.1 Hz to 1 kHz when the plasma process is performed.

[0052] Specifically, when the plasma process is performed, the thin film formed on the crystal oscillator in the wafer sensor utilizing the crystal oscillator of the present invention is etched and removed, thereby increasing the frequency.

[0053] At this time, the thickness of the thin film measured through the etching process in the above-mentioned measuring unit may fluctuate significantly due to contamination caused by plasma, and additionally, if the etching process is not performed and instead a polymer is deposited causing a decrease in the measured frequency, it can be determined as an abnormal process.

[0054]

[0055] In this case, the present invention installs a crystal oscillator on the PCB module, and multiple crystal oscillators may be installed, each spaced apart. The location where the crystal oscillators are installed is not separately determined and is not limited to any location suitable for measuring frequency changes on the PCB module.

[0056] Thus, the wafer sensor utilizing a quartz crystal oscillator of the present invention can secure production yield by diagnosing the overall etching pattern of the wafer in real time and reduce process costs through the optimization of the preventive maintenance (PM) cycle.

[0057]

[0058] In addition, the present invention may include a silicon wafer (400).

[0059] At this time, the silicon wafer of the present invention is formed on the upper part of the crystal oscillator, and the silicon wafer is positioned between the receiving oscillator and the conductive protective layer and can perform the role of conducting electricity by contacting the crystal oscillator.

[0060]

[0061] In addition, the present invention may include a conductive protective layer (500).

[0062] At this time, the present invention is characterized in that the conductive protective layer of the present invention is formed on a surface and includes pores penetrating the protective layer, and since the conductive protective layer with the formed pores is conductive, it has the effect of blocking electrical noise introduced by plasma and may have the effect of minimizing the direct influence of plasma on the sensor surface.

[0063] In addition, the diameter of the pores formed in the conductive protective layer of the present invention may be 0.1 mm to 5 mm.

[0064] At this time, the reason the diameter of the pores of the conductive protective layer of the present invention is 0.1 mm to 5 mm is that the size of the holes formed in the protective film is such that it has the effect of preventing or minimizing direct collision of ions by plasma or the inflow of electrical noise.

[0065] In addition, the conductive protective layer used in the present invention is composed of a group of conductive materials, such as metals or metal compounds, and the reason for being composed of the aforementioned materials is that they must possess electrical conductivity in order to eliminate electrical noise.

[0066] At this time, the reason the thickness of the conductive protective layer of the present invention is 0.1 (mm) to 5.0 (mm) is that if the thickness of the protective layer is thinner than 0.1 (mm), there may be a problem in that the effect of blocking direct collisions of particles entering from the plasma or electrical noise signals is significantly reduced, and if it is thicker than 5.0 (mm), there may be a problem in that the amount of contaminants entering from the external environment is limited, which may cause too large an error in measuring and monitoring the velocity of the material or environmental contamination inside the chamber, which is the original purpose.

[0067] At this time, the wafer sensor utilizing the crystal oscillator of the present invention is characterized in that the total thickness is 1 mm to 10 mm.

[0068] In addition, the total mass of the wafer sensor utilizing the above-mentioned crystal oscillator may be 150g to 500g.

[0069] At this time, the wafer sensor utilizing the crystal oscillator of the present invention is capable of wireless communication by the principles of Bluetooth or NFC and can transmit data of the crystal oscillator in real time.

[0070] At this time, referring to FIG. 3, the conductive protective layer of the present invention can change the movement path of ions generated during the plasma process based on the substrate.

[0071] At this time, by changing the movement path of ions generated during the plasma process of the present invention of FIG. 3, the amount of ions or substances reaching the surface of the sensor can be limited, and electrical noise entering the sensor can be minimized by blocking direct contact between the sensor and the plasma.

[0072] Thus, the wafer-shaped sensor utilizing a quartz crystal oscillator according to one embodiment of the present invention can eliminate noise by forming a conductive layer on the surface of the quartz crystal oscillator, and the sensor can be used for a long period of time, thereby increasing the lifespan of the sensor and reducing process costs through the optimization of the preventive maintenance (PM) cycle.

[0073]

[0074] A method for real-time monitoring of a plasma etching process according to another embodiment of the present invention is described.

[0075] A real-time monitoring method for a plasma etching process according to another embodiment of the present invention may include: a plasma generating chamber that generates plasma light to etch a wafer or deposit a thin film on a wafer; a measuring unit that detects the thickness of the etched thin film and the degree of contamination of the plasma when the plasma process is operated by a wafer sensor utilizing a crystal oscillator of claim 1, installed on the upper part of an electrostatic chuck inside the plasma generating chamber; and a control unit located outside the plasma generating chamber that monitors the plasma process state by determining it as an abnormal process when the thickness of the etched thin film and the degree of contamination measured by the measuring unit differ from a preset reference value.

[0076] First, the present invention may include a plasma generation chamber.

[0077] If the above plasma generation chamber is a chamber that generates plasma light to etch a wafer, it can be used without restriction on type.

[0078]

[0079] In addition, the present invention may include a measuring unit.

[0080] At this time, the measuring unit is installed inside the plasma generation chamber, and the thickness of the etched thin film and the degree of plasma contamination can be detected by a wafer sensor utilizing the crystal oscillator when the plasma process is operated.

[0081] At this time, the wafer sensor utilizing the above-mentioned crystal oscillator is not in an electrically separated state on the electrostatic chuck installed inside the plasma chamber, but exists in an electrically connected state, so that a potential difference can be intentionally applied.

[0082]

[0083] In addition, the present invention may include a control unit.

[0084] At this time, the control unit is located outside the plasma generation chamber, and can monitor the plasma process state by determining it as an abnormal process if the thickness of the thin film etched by the measurement unit and the measured contamination level differ from preset reference values.

[0085] In addition, the control unit can determine that it is a normal process if the thickness of the thin film etched by the measurement unit and the measured contamination level are the same as the preset reference values.

[0086] At this time, the thickness of the etched thin film and the contamination level of the plasma light measured by the above-mentioned measuring unit may vary depending on the etching process, and if drift is induced by the frequency increasing as the thin film layer on the wafer is etched at the measuring unit, it can be determined as an abnormal process.

[0087]

[0088] The present invention will be explained in more detail below through examples. These examples are solely for illustrating the present invention, and the scope of the present invention is not limited by these examples.

[0089]

[0090] Example: Real-time monitoring method for plasma etching process

[0091] Referring to Fig. 4, a method for real-time monitoring of the plasma etching process using a wafer sensor utilizing a crystal oscillator is described.

[0092] First, the thickness of the thin film etched during the plasma etching process and the contamination level of the plasma light were measured in the measurement unit.

[0093] At this time, the crystal oscillator has a natural frequency of 6 MHz, and utilizes the principle that the thin film layer formed on the wafer on the surface of the crystal oscillator is etched, thereby increasing the frequency to a certain level.

[0094] Next, the thickness of the thin film measured through the etching process in the above-mentioned measuring unit may fluctuate significantly due to contamination caused by plasma, and additionally, if the frequency decreases because the polymer is deposited instead of the etching process, it can be determined as an abnormal process.

[0095]

[0096] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0097] The scope of the present invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

[0098]

[0099] 100: Silicon or conductive wafer

[0100] 200: PCB Module

[0101] 300: Crystal oscillator

[0102] 400: Silicon wafer

[0103] 500: Conductive protective layer

Claims

1. Wafer; A PCB module formed on the wafer above; A crystal oscillator spaced apart and installed on the above PCB module; A silicon wafer formed on the upper part of the above-mentioned crystal oscillator; and A wafer sensor utilizing a quartz crystal, characterized by including a conductive protective layer formed on the upper surface of the silicon wafer and having pores formed on its surface.

2. In Paragraph 1, A wafer sensor utilizing a quartz crystal, characterized in that the wafer comprises silicon or a conductive metal.

3. In Paragraph 1, The above PCB module is, A wafer sensor utilizing a crystal oscillator, characterized by including a CPU (central processing unit), a semiconductor device, or a battery power source.

4. In Paragraph 1, The above crystal oscillator is, A crystal that is composed of quartz and is a disc-shaped piezoelectric material; and A wafer sensor utilizing a quartz crystal, characterized by being made of metal and including electrode layers deposited on the upper and lower surfaces of the quartz crystal.

5. In Paragraph 1, A wafer sensor utilizing a crystal oscillator, characterized in that the diameter of the pores formed on the surface of the conductive protective layer is 0.1 mm to 5 mm.

6. In Paragraph 1, A wafer sensor utilizing a crystal oscillator, characterized in that the conductive protective layer is a conductive material made of a metal or a metal compound.

7. In Paragraph 1, A wafer sensor utilizing a quartz crystal, characterized in that the total thickness of the wafer sensor utilizing the quartz crystal is 1 mm to 10 mm.

8. In Paragraph 1, A wafer sensor utilizing a quartz crystal, characterized in that the total mass of the wafer sensor utilizing the quartz crystal is 150g to 500g.

9. In Paragraph 1, A wafer sensor utilizing a quartz crystal oscillator, characterized by being capable of wireless communication.

10. A plasma generating chamber that generates plasma light to etch a wafer or deposit a thin film on a wafer; A measuring unit that detects the thickness of the etched thin film and the degree of plasma contamination when the plasma process is operated by a wafer sensor utilizing the crystal oscillator of claim 1, installed on the upper part of the electrostatic chuck inside the plasma generation chamber; and A real-time monitoring system for a plasma etching process, characterized by including a control unit located outside the plasma generation chamber, which monitors the plasma process state by determining it as an abnormal process when the thickness and contamination level of the etched thin film measured by the measurement unit differ from preset reference values.

11. In Paragraph 10, A real-time monitoring system for a plasma etching process, characterized in that the control unit determines the process to be normal when the thickness and contamination level of the etched thin film measured by the measurement unit are the same as preset reference values.

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