KR20190120993A - Fabrication method of pressure sensors with high sensitivity and reliability - Google Patents

Abstract

According to one aspect of the present invention, provided is a manufacturing method of a high sensitivity and high reliability pressure sensor. The manufacturing method of the high sensitivity and high reliability pressure sensor can comprise: a step of forming a membrane on a front surface of the substrate; a step of exposing the membrane to the outside by removing at least a part of a back surface of the substrate; and a step of forming a carbon thin film on the exposed surface of the membrane. Therefore, the present invention is capable of preventing moisture absorption.

Description

Fabrication method of pressure sensors with high sensitivity and reliability

The present invention relates to a method of manufacturing a pressure sensor, and more particularly, it is applied to the improvement of characteristics of a micromembrane thin film, which is required for detecting an external physical quantity change when manufacturing a micro sensor, and typically, the production of a MEMS (Micro Electro Mechanical Systems) pressure sensor. MEMS-based high sensitivity and high reliability pressure sensor that can be applied to improve the performance of each micro sensor by improving the characteristics of the membrane thin film of various sensors such as process, thermopile, flow sensor, bolometer, chemical sensor, and heater It is about a manufacturing method.

Sensors are becoming smaller, complex, and intelligent, and have emerged as a key element technology for the realization of smart society as a medium of convergence between industries and between humans and devices. In order to meet these requirements, the development of high sensitivity and high performance sensor technology that can extend the measurement range and operating environment range of the conventional sensor technology is required.

Among the sensors, the pressure sensor market accounts for more than 75% of the overall market, and CAGR is expected to grow more than 8%. The main use of the pressure sensor is mounted on a mobile device to accurately measure atmospheric pressure and indoor and outdoor altitudes to calculate momentum and locate locations in buildings.

According to data released by Canalys in 2014, the home appliance and automotive sectors of the Internet of Things market are currently being formed, and the blue ocean market is expected to grow in several years. In particular, the water level pressure sensor, which recognizes the water level and location, is a key part of the future IT core areas such as home appliances (washing machines, dishwashers, etc.) and the IoT.

Recently, advanced countries such as the United States and Europe are tightening energy / environmental regulations. In particular, the government is pursuing legislation by establishing standards such as energy ratings to regulate water and electricity consumption caused by the use of household appliances. The pressure sensors used in products directly related to these environmental regulations are mainly water level pressure sensors and air compressor pressure sensors. There is an urgent need. However, the current pressure sensor is required to develop a precision sensor to improve the precision characteristics to the limit of precision characteristics, and to develop a product that meets energy / environmental regulations.

In addition, a membrane thin film operated by an external pressure is required to fabricate a MEMS-based pressure sensor. This membrane thin film has a problem that the sensor is deteriorated in the environment exposed to moisture or chemicals exposed.

The present invention is to solve the above and technical problems, to protect the electrode of the MEMS-based pressure sensor or to solve the problem of the multi-layer structure, to improve the sensitivity characteristics of the pressure sensor, to prevent moisture absorption, to external chemicals (chemical) It is an object of the present invention to provide a method of manufacturing a highly sensitive and highly reliable pressure sensor which can prevent deterioration of characteristics due to the deterioration and, in particular, minimize the loading effect generated during deep reactive ion etching (DRIE) etching of the back surface of the wafer. However, these problems are exemplary, and the scope of the present invention is not limited thereby.

According to one aspect of the invention, there is provided a method of manufacturing a high sensitivity and high reliability pressure sensor. The method of manufacturing the high sensitivity and high reliability pressure sensor may include forming a membrane on the front surface of the substrate; Exposing the membrane to the outside by removing at least a portion of the back side of the substrate; And forming a carbon thin film on the exposed side of the membrane.

In the method of manufacturing the high sensitivity and high reliability pressure sensor, the carbon thin film is an amorphous carbon film, and may include amorphous graphite.

In the manufacturing method of the high sensitivity and high reliability pressure sensor, forming the carbon thin film, ECR-CVD (Electron Cyclotron Resonance plasma assisted Chemical Vacuum Deposition), PECVD (Plasma Enhanced Chemical Vacuum Deposition), Pulse Laser Ablation and Magnetron Sputtering It may include the step of depositing the amorphous carbon film using any one of.

In the method of manufacturing the high sensitivity and high pressure sensor, the carbon thin film may be formed by depositing a sputtering method using a graphite target, and attaching a shadow-cover mask to a rear surface of the substrate. And then selectively depositing the amorphous carbon film mainly on the membrane only.

In the manufacturing method of the high sensitivity and high pressure sensor, the step of forming the membrane, forming a first insulating film on the substrate; Forming an electrode thin film on the first insulating film; Removing at least a portion of the electrode thin film by using a photolithography method to form an electrode pattern on the first insulating film; Forming a second insulating film on the electrode pattern and the first insulating film; And forming a contact hole by etching and removing at least a portion of the second insulating layer, and forming a metal wire to be connected to the electrode pattern by using the contact hole.

In the manufacturing method of the high sensitivity and high reliability pressure sensor, the step of forming the first insulating film, a SiN thin film on the substrate using a low pressure chemical vapor deposition (LPCVD) method or a plasma enhanced chemical vacuum deposition (PECVD) method Or depositing a SiO ₂ thin film.

In the method of manufacturing the high sensitivity high reliability pressure sensor, the forming of the second insulating film may include forming a SiN thin film and an SiO ₂ thin film on the electrode pattern and the first insulating film by using a plasma enhanced chemical vacuum deposition (PECVD) method. It may include the step of depositing sequentially.

In the method of manufacturing the high sensitivity high reliability pressure sensor, the forming of the metal wire may include forming the contact hole by using a lift-off method, depositing Ti metal or Al metal, and depositing the electrode. And electrically connecting with the pattern. Alternatively, after forming a contact hole and depositing an electrode metal (Ti / Al, Ti / TiN / Al laminated metal film), the electrode metal is connected to the electrode pattern through exposure and etching using conventional techniques. It may include the step of forming a wiring.

In the method of manufacturing the high sensitivity and high reliability pressure sensor, exposing the membrane to the outside by removing at least a portion of the rear surface of the substrate, after etching to remove the oxide film or the metal film of the substrate by using a mask (mask) The method may include exposing the membrane to the outside by removing at least a portion of the substrate using an ICP-RIE method.

In the method of manufacturing the high sensitivity and high reliability pressure sensor, the method may include sequentially performing a dicing process and a packaging process after the forming of the carbon thin film.

In the method of manufacturing the high sensitivity high reliability pressure sensor, the forming of the carbon thin film may include forming the carbon thin film so as to be embedded in a rear surface of the first insulating film.

According to the embodiment of the present invention made as described above, it is possible to improve the sensitivity of the pressure sensor, it is possible to prevent damage from etching chemicals, cleaning chemicals, chemicals used during development during the manufacturing process In addition, it is possible to implement a method of manufacturing a highly sensitive and highly reliable pressure sensor capable of minimizing damage to the membrane underlayer by minimizing damage to the edge of the membrane due to etch undercut and moisture and chemical contact. Of course, the scope of the present invention is not limited by these effects.

1 to 6 are process flowcharts schematically illustrating a method of manufacturing a high sensitivity and high reliability pressure sensor according to an embodiment of the present invention.
7 is a schematic diagram illustrating the structure of a diaphragm and a substrate manufactured by a conventional pressure sensor process technique.
8 is a cross-sectional view schematically illustrating the structure of a conventional silicon piezoresistive MEMS pressure sensor.
FIG. 9 is a schematic diagram illustrating a structure and a circuit diagram of the pressure sensor of FIG. 8.
10 is a cross-sectional view schematically showing the structure of a membrane in a conventional silicon piezoresistive pressure sensor.
FIG. 11 and FIG. 12 are schematic diagrams showing damaged parts of the pressure sensor shown in FIG. 10, and images of profiles of depths are analyzed by optical microscope.
Figure 13 is a photograph of the membrane surface showing the normal and abnormal behavior observed with a shape measurement laser microscope.
14 is a graph showing an example of pressure sensor output characteristics.
15 is a graph comparing Young's modulus values conventionally published in the literature.
FIG. 16 schematically illustrates a shadow mask used in a method of manufacturing a high sensitivity high reliability pressure sensor according to an exemplary embodiment of the present invention.
17 is a photograph of a dicing and packaging process of a pressure sensor implemented by a method of manufacturing a high sensitivity and high pressure sensor according to an embodiment of the present invention.
FIG. 18 is a photograph analyzed by an optical microscope after Si etching of a sample implemented by a method of manufacturing a high-sensitivity, high-reliability pressure sensor according to an embodiment of the present invention.
19 is a graph comparing output values according to an applied pressure of pressure sensor samples according to an experimental example of the present invention.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art, and the following examples can be modified in various other forms, and the scope of the present invention is It is not limited to an Example. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In general, the pressure sensor determines the size of the diaphragm and the thickness of the membrane depending on the pressure sensing range. 7 is a schematic diagram illustrating the structure of a diaphragm and a substrate manufactured by a conventional pressure sensor process technique. 7 (a) is a photograph of a cross-sectional view of a conventional MEMS pressure sensor membrane structure with a scanning electron microscope, and FIG. 7 (b) is a photograph of a surface of the structure by a scanning electron microscope.

In the case of the piezoresistive pressure sensor, the pressure sensor method is configured in the form of a Wheatstone bridge and operates by a piezoresistive effect. An electrode having a piezoresistive effect is formed on the diaphragm, and externally acting pressure deforms the diaphragm. For this reason, the principle that a gauge changes length and a resistance changes is used. That is, L mainly changes at R = ρL / A (ρ: specific resistance, L: length, A: cross-sectional area).

8 is a cross-sectional view schematically illustrating the structure of a conventional silicon piezoresistive MEMS pressure sensor, and FIG. 9 is a diagram schematically illustrating a structure and a circuit diagram of the pressure sensor of FIG. 8.

8 and 9, the silicon pressure sensor is disposed on the silicon diaphragm in the form of a Wheatstone bridge, which is a kind of piezoresistor indicating sensitivity to shear stress. In the case of the square diaphragm, as shown in the following equation (1), the maximum shear stress generation point is the edge of the diaframe, and the shear stress is zero at the center of the diaframe.

Equation (1): σ _max = constant * P * (a / h) ²

Where a is the diameter of the membrane and h is the thickness of the membrane

Conventional pressure sensors detect motion with electronic sensing circuits fabricated on top of the membrane. The membrane forms a closed chamber at room temperature and atmospheric pressure (1 atmosphere), with the sealed chamber being the reference pressure. When the external pressure on the membrane is applied, the sensing circuit detects the pressure change and measures the pressure.

Meanwhile, in order to detect a change in pressure, the pressure sensor forms a piezoresistive thin film and a metal layer on which a membrane is formed to manufacture a Wheatstone bridge. 9 shows an electronic sensing circuit of a pressure sensor. In this case, the sensor measurement measures the voltage change according to the reference current (the state that no pressure is applied) and the external pressure when a constant voltage is applied to the bridge circuit. In general, each characteristic value must be converted into a voltage signal that can be transmitted to an ECU (Electric Control Unit) by a separate circuit, and an application specific integrated circuit (ASIC) is applied as a main component of the circuit. At this time, the thin film used as the electrode must satisfy all the operating pressure range, temperature range, humidity range and pressure resistance range.

10 is a cross-sectional view schematically showing the structure of a membrane in a conventional silicon piezoresistive pressure sensor. Where a is the radius of the membrane and h is the thickness of the membrane.

FIG. 11 and FIG. 12 are schematic diagrams showing damaged parts of the pressure sensor shown in FIG. 10, and images of profiles according to depths are analyzed by a shape measuring laser optical microscope.

In the structure shown in FIG. 10, the sensitivity of the shear stress type pressure sensor may be expressed by Equation (1). As can be seen from the equation (1) it can be seen that the detection range of the desired pressure sensor is determined by the type of material, membrane size and thickness to determine the constant value.

On the other hand, the technology for forming the membrane structure has been etched using the wet etching method until now. However, this technique is difficult to manufacture a large amount of sensors per unit area. In particular, it is difficult to apply to new materials such as SiC, GaN, etc. Recently, a technique of applying a substrate by a dry etching method is increasing.

A method of forming a membrane structure using a dry etching method is typically to produce a pressure sensor based on Si or SiC. For example, when forming a membrane, which is a pressure sensitive film by dry etching, on the back side of a wafer, as shown in FIGS. 11 and 12, in an SOI substrate structure generated in a wafer or in a Si, SiC bulk substrate. Damage to the underlying oxide film and etch undercut due to the difference in etching uniformity causes damage to the edge of the membrane (the area indicated by the arrow in FIG. 11).

In addition, Figure 13 is a photograph of the membrane surface showing the normal and abnormal behavior observed with a shape measuring laser microscope, Figure 14 is a graph showing an example of the pressure sensor output characteristics.

Referring to FIGS. 13 and 14, when the sensor is exposed to harsh environments such as high humidity, high temperature, high pressure, and chemical exposure environments, and when the sensor is used for a long time, the Si substrate under the membrane exposed by external moisture or chemicals, Deterioration of the SiO ₂ thin film layer occurs, resulting in deterioration of reliability.

In order to solve this problem, in the present invention, by preventing the damage caused by chemicals during long-term use in harsh environments, by depositing a carbon thin film on the lower portion of the pressure-sensitive membrane to improve the reliability to improve the edge characteristics by etching In addition, the present invention provides a method of manufacturing a highly sensitive and reliable pressure sensor capable of withstanding the external environment caused by chemicals.

Hereinafter, with reference to the accompanying drawings will be described in detail a method of manufacturing a high sensitivity high reliability pressure sensor of the present invention.

1 to 6 are process flowcharts schematically illustrating a method of manufacturing a high sensitivity and high reliability pressure sensor according to an embodiment of the present invention.

1 to 6, a method of manufacturing a highly sensitive and highly reliable pressure sensor 100 according to an embodiment of the present invention may include forming a membrane 60 on a front surface of a substrate 10. Exposing the membrane 60 to the outside by removing at least a portion of the backside of 10) and forming the carbon thin film 70 on the exposed side of the membrane 60. Here, the carbon thin film 70 is an amorphous carbon film, for example, may include amorphous graphite (graphite). In addition, the membrane 60 refers to a structure in which the first insulating film 20, the electrode pattern 35, the second insulating film 40, and the metal wiring 50 are stacked in this order, and the underlying film of the membrane 60 is outside. It can be exposed to change the pressure.

In addition, the substrate 10 may include, for example, a semiconductor substrate such as Si, SiC, and GaN. For example, on the substrate 10 is a buried oxide for fabricating an SOI wafer. In this case, the SOI substrate 10 may include Si or SiC.

15 is a graph comparing Young's modulus values conventionally published in the literature.

Referring to FIG. 15, in general, the modulus of elasticity of carbon is smaller than that of Si, and thus the sensitivity of the membrane 60 may be improved. When a portion of the Si film is converted to the carbon thin film 70, the effective Young's modulus value of the film decreases, which is more deformed at the external pressure. For this reason, since a strain value becomes large compared with single crystal silicon, a sensitivity increases.

In the process of manufacturing the pressure sensor 100, after the backside etching of the Si substrate 10, the front piezoresistive electrode pattern 30 and the metal wiring 50 are processed, and the subsequent piezoresistive electrode (not shown) and the metal wiring (not shown) are performed. ), Damage to the pressure sensor 100 may be prevented from etching chemicals, cleaning chemicals, and developer chemicals during the exposure process.

When the pressure sensor 100 is manufactured based on Si or SiC, the edge of the membrane 60 is damaged due to the undercut due to the etching generated when the membrane 60, which is a pressure sensing film by the dry etching, is formed on the back side of the wafer substrate 10. In order to minimize contact due to moisture and chemicals, the amorphous carbon thin film 70 was deposited to minimize damage to the underlying film of the membrane 60.

More specifically, the first insulating film 20 may be formed on the substrate 10. The first insulating layer 20 deposits a SiN thin film, a SiO ₂ thin film, or a SiN / SiO ₂ stacked thin film on the substrate 10 by using a low pressure chemical vapor deposition (LPCVD) method or a plasma enhanced chemical vacuum deposition (PECVD) method. can do.

Thereafter, the electrode thin film 30 may be formed on the first insulating layer 20. The electrode thin film 30 is a conventionally known electrode thin film 30 such as a Si epi thin film, a doped poly electrode, a NiCr (80% Nr: 20% Cr, hereinafter NiCr alloy) alloy which is a piezoresistive metal film. ) Is deposited to a thickness of about 0.1 μm to 1 μm depending on the product application thickness.

Thereafter, at least a portion of the electrode thin film 30 may be removed using a photolithography method to form the electrode pattern 35 on the first insulating layer 20. The electrode pattern 30 may be understood as a piezoresistive electrode. The deposited electrode thin film 30 is formed into an electrode pattern 35 through an exposure and etching process.

After the electrode pattern 35 is formed, the second insulating layer 40 may be formed on the electrode pattern 35 and the first insulating layer 20. The second insulating film 40 is sequentially deposited on the electrode pattern 35 and the first insulating film 20 and the SiO ₂ thin film by using a plasma enhanced chemical vacuum deposition (PPECVD) method, or in reverse order. . Here, the second insulating film 40 may be understood as a protective film for protecting the electrode pattern 35.

After forming the second insulating film 40, a contact hole (not shown) is formed by etching and removing at least a portion of the second insulating film 40, and using the contact hole, the electrode pattern 35. The metal wire 50 may be formed to be connected to the metal wire 50.

For example, in order to connect the electrode pattern 35 and the metal wiring 50, contact holes are formed by an exposure and etching process, and Ti and Al metals are formed in a lift-off manner. In this case, the metal wire 50 may use a Ti / TiN thin film or a Ta thin film to improve reliability at high temperature. In addition, the Al wiring may be formed by etching the Al metal after the exposure process after Al thin film deposition.

Thereafter, the rear surface of the substrate 10 is etched by a Si deep etch method to remove the oxide film or the metal film formed on the rear surface of the substrate 10. At this time, the mask oxide film (SiO ₂ ) on the back surface of the substrate 10 is about 1 ㎛ thickness in consideration of the etching selectivity of the substrate 10 and the mask oxide film. In the case of the SiC thin film, the Ni thin film is etched using a thickness of about 1 μm to 4 μm on the Ti or Cr seed layer.

After etching the back surface of the substrate 10 using a mask oxide film or a Ni metal film, at least a portion of the substrate 10, ie, a Si or SiC substrate, is etched by using an inductive coupled plasma-reactive ion etching (ICP-RIE) method. By removing the membrane 60, the membrane 60 may be exposed to the outside. Here, only the membrane 60 having a size of about 5 μm to 20 μm is left according to the application range of the pressure sensor 100.

Subsequently, in order to improve the characteristics of the membrane 60 and possibly reduce residual stress during the manufacturing process of the pressure sensor 100, an amorphous carbon thin film 70 is deposited on the back surface of the membrane 60. In this case, the carbon thin film 70 may be formed using any one of ECR-CVD (Electron Cyclotron Resonance plasma assisted Chemical Vacuum Deposition), PECVD (Plasma Enhanced Chemical Vacuum Deposition), Pulse Laser Ablation, and Magnetron Sputtering. The carbon film may be deposited, but various deposition methods may be applied in consideration of the type and process time of the substrate and the membrane. The properties of the carbon thin film 70 is not only a deposition method, but also changes the characteristics of the thin film according to the process conditions during deposition.

For example, in order to obtain a thin film having soft graphite shape characteristics with sp2 bonds, the amorphous carbon thin film 70 is a graphite (C, graphite) target using a graphite (C, graphite) at a sputter reactor at a frequency of 13.56 MHz, a power of about 50 W to 300 W Was applied, and amorphous graphite was deposited by sputtering at a pressure range of about 3 x 10 ^-3 torr to 3 torr and room temperature.

When depositing the carbon thin film 70, as shown in FIG. 16 to selectively deposit the carbon thin film 70 as much as possible only on the back side of the substrate 10, ie, only on the membrane 60 of the pressure sensor, as shown in FIG. 16. deposit using a shadow-cover mask. After etching the substrate Si or SiC to a thickness of about 100㎛ to 400㎛ and manufacturing a shadow mask in consideration of design rules about 10㎛ to 200㎛ larger than the membrane 60 when depositing the carbon thin film 70 By depositing the carbon thin film 70 in a state attached to the back of the substrate 10. As such, the deposited carbon thin film 70 has a low coefficient of friction, high hardness, and durability to improve pressure sensor characteristics.

The carbon thin film 70 may be formed in the recess provided in the rear surface of the substrate 10, but may be formed only on the bottom surface of the membrane 60. Alternatively, when the rear surface of the substrate 10 is etched and removed, at least a portion of the first insulating film 20 constituting the membrane 60 may be removed together. In this case, in order to prevent edge damage of the membrane 60, the carbon thin film 70 may be formed to be buried in the rear surface of the first insulating film 20.

In summary, the carbon thin film 70 is deposited on the lower surface of the membrane 60 and the sidewalls of the recesses provided in the substrate 10 to protect the membrane 60 from the harsh external environment. 70 is not deposited on the substrate 10 according to the structure of the membrane 60, but is formed in a form embedded in the lower portion of the membrane 60, the deposition thickness using the deposition principle on the side wall of the recess provided in the substrate 10 Minimize That is, the formation of the carbon thin film 70 is minimized on the sidewall of the substrate 10 and the lower surface of the substrate 10 at the portion where the membrane 60 is opened. This is to use a conventional bonding process in subsequent packaging processes.

17 is a photograph of a dicing and packaging process of a pressure sensor implemented by a method of manufacturing a high sensitivity and high pressure sensor according to an embodiment of the present invention.

Referring to FIG. 17, after the carbon thin film 70 is formed on the bottom surface of the membrane 60, a dicing process and a packaging process may be sequentially performed. Specifically, as shown in (a) of FIG. 17, after the pressure sensor is disposed on the PCB substrate and the ROIC element is wire bonded, as shown in (b) of FIG. 17, the plastic after the capping is shown. It can be packaged into moldings and applied to the product.

Hereinafter, embodiments to help understanding of the present invention will be described. However, the following experimental examples are only for helping understanding of the present invention, and the present invention is not limited only to the following examples.

As an experimental example of the present invention, an SOI substrate was used, and an in-situ P-doped poly Si thin film was deposited to a thickness of 0.2 um-1 um by the LPCVD method. At this time, P doping was deposited at a concentration of about 10 ²⁰ (atom / cm 3) at 700 ° C. at a pressure and temperature of 50 torr using PH ₃ gas. The deposited thin film was intended to reduce the activation of the doping element and the TCR value through RTA (metal heat treatment) treatment. Thereafter, a poly Si thin film is formed through exposure and etching, and then a resistor is formed, followed by deposition of a SiN thin film and a 300 nm thick SiO ₂ thin film using a 100 nm thick PECVD method as a second insulating film as a protective film. It was.

After the formation of the second insulating layer, contact holes were formed by exposure and etching processes, and 20 nm thick Ti and 300 nm thick Al metal wires were formed by a lift-off method. Thereafter, the wafer backside is Si deep etched by a conventional method. Thereafter, the Si substrate was etched by the ICP-RIE process, leaving only a membrane of about 5-20 μm. Afterwards, the amorphous carbon film is supplied with a power of about 50 W to 300 W at a 13.56 MHz frequency in a sputter reactor using a graphite (C) graphite target, and a pressure range of about 3 x 10 ^-3 torr to 3 torr and a room temperature Amorphous graphite was deposited by sputtering at to prepare a pressure sensor sample.

In order to compare the characteristics of the prepared pressure sensor sample, a comparative sample without a carbon thin film was prepared in the same manner.

FIG. 18 is a photograph analyzed by an optical microscope and a shape measuring laser microscope of a sample implemented by a method of manufacturing a high sensitivity and high pressure sensor according to an embodiment of the present invention.

FIG. 18 (a) is a photograph obtained by analyzing an optical microscope on the back side after etching the Si, FIG. 18 (b) is a photograph analyzed by an optical microscope the back surface on which the carbon thin film is deposited, and FIG. It is a photograph observed with a microscope, Figure 18 (d) is a photograph analyzing the profile according to the depth.

In addition, Figure 19 is a graph comparing the output value according to the applied pressure of the pressure sensor samples according to the experimental example of the present invention.

Referring to FIGS. 18 and 19, the output value according to the increase in the pressure of the water (H ₂ O) was confirmed that the sample of the present invention is higher than that of the comparative sample. In addition, it is determined that the damage to the membrane underlayer is minimized by depositing an amorphous carbon thin film on the underlayer of the membrane in the sample implemented by the method of manufacturing a high sensitivity and high pressure sensor according to an embodiment of the present invention.

As described above, the present invention improves the sensitivity of the pressure sensor by depositing amorphous carbon on the back side of the wafer, and when the front piezoresistive electrode and the metal wiring process are performed after etching the Si backside during the pressure sensor manufacturing process, subsequent piezoresistive electrodes, It is possible to prevent damage from etching chemicals or cleaning chemicals generated during the formation of metal wirings, and the developer during the exposure process.

On the other hand, the present invention is applied to the improvement of the characteristics of the micro-membrane thin film, which is required for sensing the external physical quantity change when manufacturing a micro sensor. Typically, the MEMS-based pressure sensor manufacturing process, thermopile, flow sensor, bolometer, chemical sensor and heater, such as to improve the characteristics of the membrane thin film of various sensors can be applied to each micro sensor performance improvement.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

10: substrate
20: first insulating layer
30: electrode thin film
35 electrode pattern
40: second insulating layer
50: metal wiring
60: membrane
70: carbon thin film
80: shadow mask
100: pressure sensor

Claims (11)

Forming a membrane on the front side of the substrate;
Exposing the membrane to the outside by removing at least a portion of the back side of the substrate; And
Forming a carbon thin film on the exposed side of the membrane;
Including,
Manufacturing method of high sensitivity and high reliability pressure sensor. The method of claim 1,
The carbon thin film is an amorphous carbon film, and includes amorphous graphite (graphite),
Manufacturing method of high sensitivity and high reliability pressure sensor. The method of claim 2,
Forming the carbon thin film,
Depositing the amorphous carbon film using any one of Electron Cyclotron Resonance plasma assisted Chemical Vacuum Deposition (ECR-CVD), Plasma Enhanced Chemical Vacuum Deposition (PECVD), Pulse Laser Ablation, and Magnetron Sputtering,
Manufacturing method of high sensitivity and high reliability pressure sensor. The method of claim 2,
Forming the carbon thin film,
Depositing by a sputtering method using a graphite target, and attaching a shadow-cover mask to the backside of the substrate and selectively depositing the amorphous carbon film only on the membrane,
Manufacturing method of high sensitivity and high reliability pressure sensor. The method of claim 1,
Forming the membrane,
Forming a first insulating film on the substrate;
Forming an electrode thin film on the first insulating film;
Removing at least a portion of the electrode thin film by using a photolithography method to form an electrode pattern on the first insulating film;
Forming a second insulating film on the electrode pattern and the first insulating film; And
Forming a contact hole by etching and removing at least a portion of the second insulating layer, and forming a metal wire to be connected to the electrode pattern by using the contact hole;
Including,
Manufacturing method of high sensitivity and high reliability pressure sensor. The method of claim 5,
Forming the first insulating film,
Depositing a SiN thin film or a SiO ₂ thin film on the substrate using a low pressure chemical vapor deposition (LPCVD) method or a plasma enhanced chemical vacuum deposition (PECVD) method;
Manufacturing method of high sensitivity and high reliability pressure sensor. The method of claim 5,
Forming the second insulating film,
Sequentially depositing a SiN thin film and a SiO ₂ thin film on the electrode pattern and the first insulating film by using a plasma enhanced chemical vacuum deposition (PECVD) method.
Manufacturing method of high sensitivity and high reliability pressure sensor. The method of claim 5,
Forming the metal wires,
Forming the contact hole using a lift-off method and depositing Ti metal or Al metal to electrically connect the electrode pattern;
Manufacturing method of high sensitivity and high reliability pressure sensor. The method of claim 1,
Exposing the membrane to the outside by removing at least a portion of the back side of the substrate,
Etching away the oxide or metal layer of the substrate using a mask, and then exposing the membrane to the outside by removing at least a portion of the substrate using an inductive coupled plasma-reactive ion etching (ICP-RIE) method. Including,
Manufacturing method of high sensitivity and high reliability pressure sensor. The method of claim 1,
After the forming of the carbon thin film comprising the step of sequentially performing a dicing (dicing) process and a packaging (packaging) process,
Manufacturing method of high sensitivity and high reliability pressure sensor. The method of claim 5,
Forming the carbon thin film,
Forming a carbon thin film so as to be buried in a rear surface of the first insulating film;
Manufacturing method of high sensitivity and high reliability pressure sensor.

Images