Patent Publication Number: US-2022223782-A1

Title: Semiconductor device

Description:
The present application is a continuation application of International Application No. PCT/JP2020/035085, filed on Sep. 16, 2020, which claims priority to Japanese Patent Application No. 2019-183863, filed on Oct. 4, 2019. The contents of these applications are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates to a semiconductor device having a sensor using a ferroelectric thin film as a piezoelectric element or a pyroelectric element. 
     (2) Description of the Related Art 
     Devices using ferroelectrics as microsensors and microactuators have been developed. Examples of such a device include a pressure sensor, an acceleration sensor, a gyro sensor, and an ink jet thin film head. 
     Among ferroelectrics, lead zirconate titanate (PbZrTiO 3 , hereinafter referred to as PZT) has excellent piezoelectric characteristics. Patent Document 1 describes a structure of a piezoelectric device having PZT which eliminates polarization processing which uses a high voltage, and prevents polarization deterioration due to usage environment, and a method of manufacturing the same. 
     PRIOR ART REFERENCE 
     Patent Document 
     [Patent document 1] WO 2014-045914 
     SUMMARY OF THE INVENTION 
     Rather than using a ferroelectric as a single actuator or a single sensor, there is a demand to use those actuators or sensors incorporating into, for example, a display panel. In an organic EL display device, a liquid crystal display device, or the like, a region where a pixel is formed needs to be flat. However, a sensor using a ferroelectric such as PZT is required to have a certain thickness. When such a sensor and a pixel forming region are stacked, unevenness occurs between a portion where the sensor is present and a portion where the sensor is not present. 
     In addition, there is a case in which the sensor is not formed on the entire surface of the display region but formed only on a portion of the display region. In this case, there is a possibility that uneven luminance or uneven color may occur between the region where the sensor is formed and the other region. The same applies to the case where a ferroelectric actuator is used as well as a sensor. 
     Such uneven luminance and uneven color are not limited to the organic EL display device and the liquid crystal display device, and the same applies to other display devices. Further, there is a possibility that regional uneven performance may occur in the semiconductor device, in addition to the display devices, when a sensor or an actuator is formed in a stacked manner with the functional area. 
     It is an object of the present invention to provide a semiconductor device, such as a display device, in which occurrence of unevenness in the function in each region is suppressed when a sensor or an actuator of ferroelectric is used in stacked with a functional region 
     The present invention solves the above problems, and the main specific means thereof are as follows. 
     (1) A semiconductor device having a PZT (lead zirconate titanate (PbZrTiO 3 ) sensor including: the PZT sensor including a lower electrode formed on a glass substrate, a PZT, an upper electrode, a first inorganic insulating film covering the upper electrode, and an upper wiring formed on the first inorganic insulating film and connected to the upper electrode through a first through-hole formed in the first inorganic insulating film; in which a polyimide film is formed over the PZT sensor; a plurality of TFTs are formed on the polyimide film, and a thickness of the polyimide film is 5 μm or more.
 
(2) A semiconductor device having a PZT (lead zirconate titanate (PbZrTiO 3 ) sensor including: the PZT sensor including a lower electrode formed on a first polyimide substrate, a PZT, an upper electrode, a first inorganic insulating film covering the upper electrode, and an upper wiring formed on the first inorganic insulating film and connected to the upper electrode through a first through-hole formed in the first inorganic insulating film; in which a second polyimide film is formed over the PZT sensor: a plurality of TFTs are formed on the polyimide film, and a thickness of the second polyimide film is 5 μm or more.
 
(3) A semiconductor device having a PZT (lead zirconate titanate (PbZrTiO 3 ) sensor including: the PZT sensor including a lower electrode formed on a first inorganic insulating film, which covers a polyimide film, a PZT, an upper electrode, a second inorganic insulating film covering the upper electrode, an upper wiring, formed on the second inorganic insulating film, contacting with the upper electrode via a first through hole formed in the second inorganic insulating film; in which a second polyimide film is formed on the PZT sensor, a plurality of TFTs are formed on the second polyimide film, and a thickness of the second polyimide film is 5 μm or more.
 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of an organic EL display device having a PZT sensor; 
         FIG. 2  is a cross sectional view of the display area in which a PZT sensor is formed; 
         FIG. 3  is a cross sectional view of the display area in which a PZT sensor is not formed; 
         FIG. 4  is a plan view of HAPTIC sensor (PZT sensor array); 
         FIG. 5  is a cross-sectional view along the B-B line of  FIG. 4 ; 
         FIG. 6  is a cross-sectional view along the C-C line of  FIG. 4 ; 
         FIG. 7  is figures showing a processes to form the PZT sensor; 
         FIG. 8  is a cross-sectional view of embodiment 2; 
         FIG. 9  is a cross-sectional view in the intermedium process in embodiment 3; and 
         FIG. 10  is a cross-sectional view in the intermedium process in embodiment 3 following the process of  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The contents of the present invention are described using an embodiment below. In an embodiment, a sensor using a PZT or an actuator using PZT will be described. Further, in the following embodiments, a configuration in which a PZT sensor is laminated in an organic EL display device is described, but this configuration can be similarly applied to other display devices such as a liquid crystal display device or other semiconductor devices. 
     Embodiment 1 
       FIG. 1  is a plan view showing an example of an organic EL display device to which the present invention is applied. In  FIG. 1 , a peripheral region  30  in which lead lines  21  from a scanning line, a video signal line, a power supply line, or the like are provided is formed around a display region  20  in which a pixel, a video signal line, a scanning line, a power supply line, and the like are formed. In the peripheral region  30 , a scanning line driving circuit or the like may be formed. 
     On the upper and lower sides of the display region  20  in the y direction, a so-called HAPTIC sensor  10  composed of a one dimensional array of PZT sensors is formed in a band shape in the x-direction. HAPTIC sensor  10  in this case can be used to detect a touch position, for example, when a person touches anywhere in the display area  20 . 
     That is, a predetermined vibration is generated from an individual PZT sensor, and this vibration is detected by another PZT sensor. Then, for example, when a person touches a screen, the vibration sent from the PZT sensor is changed, so that this variation is detected by the other PZT sensor and the touch position is determined. In this case, a PZT sensor for generating vibration and a PZT sensor for sensing are separately arranged, or a time sharing system may be employed in which the same PZT sensor is used for vibration generation for a predetermined time, and another time is used as a sensor for detection. 
     While the HAPTIC sensor  10  in  FIG. 1  is located slightly inwardly from the upper and lower ends of the display region  20 , the location is not limited thereto and may be located at any location where the sensor is easy to operate. Further, the HAPTIC sensor  10  may be formed in a belt-like shape extending in the y direction. Further, it may be formed in the peripheral region  30  rather than in the display region  20 . A terminal region  40  is present in the lower side in the y-direction of  FIG. 1 , and a driver IC  50  is mounted in the terminal region  40 . For example, a circuit for driving the PZT sensor is formed on the left side  52  of the driver IC  50 , and a circuit for driving the display region  20  of the organic EL display panel is formed on the right side  51  of the driver IC  50 . Further, a flexible wiring board  60  is connected to the terminal region  40  so as to supply a power source and a signal to the HAPTIC sensor  10  and the organic EL display device. By the way, in order to reduce an area of the terminal region  40 , the driver IC  50  may be mounted on the flexible wiring substrate  60 . 
       FIG. 2  is a cross-sectional view taken along line A-A of  FIG. 1  and is a cross-sectional view of a region in which a PZT sensor is present. The PZT sensor is a sensor utilizing a piezoelectric effect by PZT or a pyroelectric effect (inverse piezoelectric effect). In  FIG. 2 , a lower electrode  101  for forming a sensor is formed on a substrate  100 . The substrate  100  is formed of non-alkali glass, and has a thickness of, for example, 0.5 mm. When heat resistance of 550° C. or higher is required for the substrate  110 , a silicon substrate or the like can be used, but in this case, it is difficult to secure a large substrate area. In other words, in an organic EL display device, a plurality of display panels are formed on a large mother substrate, and therefore, it is desirable to configure the PZT sensor by a process such that a glass substrate can be used. 
     In  FIG. 2 , the lower electrode  101  is formed of a laminated film of titanium (Ti) and platinum (Pt). The titanium film is on the side of the substrate  100 , and the platinum film is on the side in contact with the PZT film  102 . Platinum is used as an upper layer of the lower electrode  101  to facilitate crystallization of the PZT film  102 . A total thickness of the lower electrode  101  is several hundreds of nanometers, but is thinner than 500 nm. 
     A PZT film  102  having piezoelectric characteristics is formed on the lower electrode  101 . The PZT film  102  has a thickness of, for example, about 2 to 3 μm. PZT film  102  may be formed by RF magnetron sputtering, for example. 
     An upper electrode  103  is formed on the PZT film  102 . The upper electrode  103  is formed of, for example, titanium (Ti), tungsten (W), or molybdenum tungsten alloy (MoW), and has a thickness of several hundreds of nanometers, but is thinner than 500 nm. The upper electrode  103  is formed with an area slightly smaller than that of the PZT film  102  or the lower electrode  101 . 
     An inorganic insulating film  104  formed of silicon oxide (SiO) film, silicon nitride (SiN) film, or the like is formed covering the upper electrode  103 , the PZT film  102 , and the lower electrode  101 . The thickness of the inorganic insulating film  104  is, for example, about 200 nm. A through hole  130  is formed in the inorganic insulating film  104  to enable connection between the upper electrode  103  and the upper wiring  105 . As shown in  FIGS. 4 and 6 , the lower electrode  101  is connected to the lower wiring  140  via the through hole  131 . 
     The upper wiring  105  is formed of any one of titanium (Ti), a stacked film of titanium and aluminum (Ti/Al), tungsten (W), a molybdenum tungsten alloy (MoW), a stacked film of molybdenum and aluminum (Mo/Al), and a stacked film of molybdenum tungsten alloy and aluminum (MoW/Al). The thickness of the upper wiring  105  is, for example, several hundreds of nanometers. A thickness of the upper wiring  105  is larger than a thickness of the lower electrode  101  or the upper electrode  103 . 
     Thus, PZT sensor is formed, but the thickness of the PZT sensor is as thick as 3 to 4 μm when the thickness of the electrode is included. It is difficult to form a display region on a PZT sensor as a result of the PZT sensor forming large irregularities. By forming a polyimide film  106  having a thickness of about 5 to 10 μm over the PZT sensor, it is possible to planarize the surface and laminate it with the PZT sensor to form a display region. The reason why the polyimide film  106  is set to 5 μm or more is to sufficiently planarize the surface of the polyimide film  106 . In order to stably form the flat polyimide film  106 , the thickness is set to 10 μm or less in consideration of process conditions. However, if the polyimide film  106  is divided into a plurality of processes, it may be made of a material having a thickness of 10 μm or more. Note that the thickness here is a maximum thickness at a position where the PZT sensor is not formed, and may be a thickness of 5 μm or less at a position where the PZT sensor is formed. 
     Since polyimide has excellent heat resistance, it can withstand the formation temperature of a semiconductor layer  108  forming a TFT (Thin Film Transistor) formed later. In the case of an organic EL display device, since the polyimide film  106  does not transmit light for image formation, it is also possible to use a non-transparent polyimide which is more excellent in heat resistance. Incidentally, when a polyimide film  106  of about 10 μm cannot be formed by one times, it can be formed in a plurality of times. 
     In  FIG. 2 , a barrier film  107  is formed on the planarized polyimide film  106 . The barrier film  107  has, for example, a three layer structure of a silicon oxide (SiO) film, a silicon nitride (SiN) film, and a silicon oxide (SiO) film. The barrier film  107  serves to prevent moisture and the like from the polyimide film  106  from contaminating the semiconductor layer  108  for the TFT. 
     A semiconductor layer  108  constituting a TFT is formed on the barrier film  107 . It is desirable to use an oxide semiconductor which can be formed at a relatively low temperature, but a low-temperature polysilicon (poly-Si) can also be used by using a heat-resistant polyimide. A channel region  1081  is formed in a portion of the semiconductor layer  108  corresponding to the gate electrode  110 , and a source/drain region  1082  is formed on both sides of the channel region  1081 . 
     A gate insulating film  109  is formed over the semiconductor layer  108 , and a gate electrode  110  is formed thereon. The gate electrode  110  is formed in the same layer with the same material as a scanning line. An interlayer insulating film  111  is formed covering the gate electrode  110 . A contact electrode  112  is formed on the interlayer insulating film  111 . The contact electrode  112  is formed in the same layer as the video signal line. The contact electrode  112  is connected to one of the source/drain regions  1082  of the TFT via the through hole  133  formed in the interlayer insulating film  111  and the gate insulating film  109 . The other of the source/drain regions  1082  of the TFT is connected to a video signal line formed on the interlayer insulating film  111  in a portion not shown. 
     At the same time as forming the through-hole  133 , the through hole  132  is formed through the interlayer insulating film  111 , the gate insulating film  109 , the barrier film  107 , and the polyimide film  106 . Through this through hole  132 , the upper wiring  105  of the PZT sensor is connected to the lead line  11 . As a result, since the video signal line and the lead line  11  can be formed on the same layer, it is possible to form the sensor driving circuit and the display device driving circuit in the common driver IC  50 . Further, the flexible wiring board  60  can be commonly formed and connected for the sensor and the display device. 
     In  FIG. 2 , an organic passivation film  113  is formed covering the interlayer insulating film  111 , the contact electrode  112 , and the like, and a reflective electrode  114  and an anode  115  for the organic EL film  117  are stacked thereon. Since the organic passivation film  113  serves as a planarization film, it is formed as thick as 2 to 3 μm. A through hole  134  is formed in an organic passivation film  113 , and a contact electrode  112 , a reflection electrode  114 , and an anode  115  are connected. The reflective electrode  114  is made of an aluminum (Al) alloy, for example, and the anode  115  is made of ITO (Indium Tin Oxide), which is a transparent metal oxide conductive film. 
     An organic film for forming a bank  116  is formed covering the anode  115  and the organic passivation film  113 . Holes are formed in the organic film at the portion where the pixel is formed, i.e., at the portion where the anode  115  is formed. A portion of the organic film other than holes becomes a bank  116 . 
     An organic EL film  117  which is a light emitting layer is formed in a hole portion of an organic film. The organic EL film  117  is formed of a plurality of organic films. Since the organic EL film  117  is very thin, so-called step disconnection tends to occur, but the bank  116  prevents disconnection of the step. 
     The cathode  118  is formed of a transparent conductive film made of metal oxide or a metal thin film covering the organic EL film  117 . A cathode  118  is formed on the entire display region in common to each pixel. Since the characteristics of the organic EL film  117  deteriorate due to impurities, particularly moisture, the protective film  119  prevents the influence of moisture from the outside. Typically, the protective film  119  has a stacked structure of an organic film and an inorganic film. 
       FIG. 3  is a cross-sectional view of the display region  20  of the portion where the HAPTIC sensor  10  is not present in  FIG. 1 . In  FIG. 3 , an inorganic insulating film  104  is formed on a substrate  100 , and a polyimide film  106  as a planarizing film is formed on the inorganic insulating film  104  to a thickness of 5 to 10 μm. The insulating film  104  and the polyimide film  106  are the same as those described in  FIG. 2 . 
     As shown in  FIG. 2  and  FIG. 3 , since the polyimide film  106  is formed thick, no irregularities exist between the portion where the PZT sensor is present and the portion where the PZT sensor is not present. Accordingly, it is possible to form a flat configuration in all of the display areas  20  and to form a uniform image. 
       FIG. 4  is a top view of the PZT sensor array in the HAPTIC sensor  10  of  FIG. 1 . In  FIG. 4 , the PZT film  102  extends in the x direction in common with each sensor common to the width y  2 . The width of the PZT film  102  in the x direction is equal to the width of the display region  20  shown in  FIG. 1 . A portion where the lower electrode  101  and the upper electrode  103  are formed becomes an individual sensor element. The size of each sensor in the planar direction is defined by an area of the upper electrode  103  and x  1 ×y  1 . 
     In  FIG. 4 , x 1  is, for example, 10 mm, and yl is, for example 10 mm. The lower electrode  101  is formed to be larger than the upper electrode  103  by about 10 μm in one side. In other words, d 1  and d 2  in  FIG. 4  are 10 μm. A width of the PZT in y direction, which is formed slightly larger than the width of the upper electrode  103 , is approximately 10.03 mm. In  FIG. 4 , d 3  and d 4  are, for example, 10 μm. An interval s 1  between the lower electrodes  101  of each sensor is 100 μm. Thus, each sensor is aligned in the x-direction at a pitch of 1.14 mm. 
     The width x 2  of the upper wiring  105  connected to the upper electrode  103  in the x direction is 100 to 500 μm, and the width x 3  of the lower wiring  140  connected to the lower electrode  101  is 100 to 500 μm. The upper wiring  105  is connected to the upper electrode  103  by a through hole  130 , and the lower wiring  140  is connected to the lower electrode  101  by a through hole  131 . 
       FIG. 5  is a cross-sectional view taken along line B-B of  FIG. 4  and is a cross-sectional view showing a relationship between the PZT sensor and the upper wiring  105 . The configuration of  FIG. 5  is similar to that described in  FIG. 2 . As shown in  FIG. 5 , the PZT sensor is covered by a thick polyimide film  106  of 5 to 10 μm, so that the upper surface of the polyimide film  106  becomes flat. 
       FIG. 6  is a cross-sectional view taken along line C-C of  FIG. 4  and is a cross-sectional view showing the relationship between the PZT sensor and the lower wiring  101 . In  FIG. 6 , a lower electrode  101  formed on a substrate  100  and a lower wiring  140  are connected to each other by a through hole  131  formed in an insulating film  104 . Since the lower electrode  101  and the lower wiring  140  are covered with a thick polyimide film  106 , the upper surface of the polyimide film  106  is flat, the same as sown in  FIG. 5 . 
       FIG. 7  shows a process for forming a PZT sensor portion. In  FIG. 7 , the left side is a process chart, and the right side is a cross-sectional view of a corresponding PZT sensor. The cross-sectional view of  FIG. 7  is the same as that of  FIG. 5 , but for convenience, the lower electrode  101  is denoted by M 1 , the upper electrode  103  is denoted by M 2 , and the upper wiring  105  is denoted by M 3 . In a chart on the left side of  FIG. 7 , a lower electrode M 1  is formed by sputtering. The lower electrode M 1  is a stacked film of titanium (Ti) and platinum (Pt), but is formed continuously by sputtering. Thereafter, photolithography (PEP: photo engraving process) is performed on the lower electrode M 1 , and then the lower electrode M 1  is patterned by dry etching. 
     Thereafter, PZT is formed, for example, by RF magnetron sputtering. Thereafter, PZT is subjected to photolithography (PZT/PEP), followed by patterning of PZT by dry etching or wet etching. 
     An upper electrode M 2  is formed by sputtering, and then a photolithography (M 2 /PEP) is performed on the upper electrode M 2 . Thereafter, the upper electrode M 2  is patterned by dry etching or wet etching. 
     An interlayer insulating film  104  which is an inorganic film is formed covering the lower electrode M 1 , the PZT, and the upper electrode M 2 . The interlayer insulating film  104  can be formed by CVD (Chemical Vapor deposition). Thereafter, photolithography (Contact/PEP) for forming a through hole  130  is performed in the interlayer insulating film  104  corresponding to the upper electrode M 2 , and thereafter, through hole  130  is formed by dry etching. 
     Thereafter, an upper wiring M 3  is formed by sputtering, and photolithography is performed on the upper wiring M 3  (M 3 /PEP). Thereafter, the upper wiring M 3  is patterned by dry etching or wet etching. 
     A polyimide film PI is formed covering PZT sensor, to a thickness of 5 to 10 μm to planarize the surface. For example, the polyimide film PI is formed as follows. A raw material of polyimide containing a polyamic acid is applied by a slit coater or the like. As the material for the polyimide, for example, “Photoneece DL-1001-C” manufactured by Toray Industries, Ltd. can be used; and the specific component of the material is 40% of gamma butyrolactone (GBL), 40% of ethyl lactate (EL), and 12% of polyamic acid. Among them, polyamic acid is imidized to form polyimide. This material is applied, for example, in a thickness of 12.5 μm. 
     After this material is applied, prebaking is performed at 105° C. for 3 minutes, and then solidified and dried. At this time, the solvent scatters, and the thickness becomes about 6.5 μm. Thereafter, the polyimide is baked. The firing procedure is broadly divided into 4 steps. In the first step, the atmosphere in the furnace is replaced with nitrogen at room temperature so that oxygen becomes 10 ppm or less. The second step heats the substrate by a temperature gradient of 4° C./min. In a second step, a reaction of imidizing polyamic acid proceeds. Thereafter, in a third step, the polyimide molecules are oriented by keeping them at high temperature for about 30 minutes. Thereafter, in a fourth step, natural cooling is performed in a nitrogen atmosphere. The thickness of the polyimide after firing is about 5 μm. 
     As described above, since the thickness of the polyimide decreases during the drying and baking period, the thickness of the polyimide material coated with the polyimide material is much larger than the final thickness. Therefore, for example, when it is desired to set the polyimide film to a thickness of about 10 μm, it is also possible to form the polyimide film two times in overlapping. Thereafter, a barrier film (Barrier) is formed of a silicon oxide (SiO) film, a silicon nitride (SiN) film, or the like over the polyimide. A large amount of water is released from the polyimide. Further, even if moisture is released from the polyimide by baking or the like, if there is a time before the display region is formed, the polyimide absorbs moisture during this time, and then this moisture is released. By forming the barrier film  107  immediately after forming the polyimide film  106 , it is possible to prevent the polyimide layer  106  from absorbing moisture from the outside. 
     Incidentally, since the adhesion between the polyimide film  106  and the glass substrate  100  is small, when the polyimide film  106  is directly formed on the glass substrate  100 , the polyimide film  106  is easily peeled off. In the constitution of the present invention, a glass substrate  100  is covered by an inorganic film  104  as a silicon oxide (SiO) film, a silicon nitride (SiN) film or a stacked film of a silicon oxide (SiO) film and a silicon nitride (SiN) film, therefore, the adhesion between the polyimide film  106  and the glass substrate  100  is stable, and it is possible to realize a highly reliable display device having HAPTIC sensor. 
     Embodiment 2 
     In the configuration shown in  FIG. 1 , the upper electrode  103  or the lower electrode  101  of the PZT sensor is connected to the sensor lead line  11  or the like by forming the through hole  132  in the polyimide film  106  having a very large thickness. However, it may be difficult to form the through hole  132  in the polyimide film  106  having a thickness of 10 μm. 
     In this case, it is also possible to pull out the lead line  11  for the PZT sensor and the lead line  21  for the display region  20  from different layers.  FIG. 8  is a sectional view showing this state. In  FIG. 8 , a polyimide film  106  covering the upper wiring  105  of the PZT sensor is not formed in the terminal region  40 . In other words, the through hole  132  in  FIG. 2  is unnecessary. An upper wiring  105  of the PZT sensor is connected to a flexible wiring board  61  for a PZT sensor in a terminal region  40 . 
     In  FIG. 8 , a lead line  21  for a display region is formed on a polyimide film  106 . Therefore, the flexible wiring board  60  for the display area and the flexible wiring board  61  for the PZD sensor are individually connected to the terminal region  40 . In the meantime, in  FIG. 8 , the driver IC  52  for the PZD sensor and the driver IC  51  for the display area are individually installed to a corresponding flexible wiring board. 
     Embodiment 3 
     There is a need for flexible display devices that do not use rigid substrates, such as glass. The present invention can also cope with such a configuration. That is, by forming a PZT sensor on a polyimide film, a flexible display device with an HAPTIC sensor can be realized. 
       FIGS. 9 and 10  are cross-sectional views showing a process for realizing such a display device. In  FIG. 9 , a second polyimide film  200  is formed on a glass substrate  100 . The second polyimide film  200  substitutes a glass substrate and serves as a flexible substrate. The second polyimide film  200  can be formed on a glass substrate  100 , which is to be removed later, by a method similar to the formation of the polyimide film  106  described in Embodiment 1. Thereafter, a second barrier film  201  is formed of a silicon oxide (SiO) film and a silicon nitride (SiN) film. The second barrier film  201  can have the same structure as that of the barrier film  107  described in Embodiment 1. The layer above the second barrier film  201  is the same as that described in Embodiment 1. 
       FIG. 10  is a cross-sectional view showing a state in which the glass substrate  100  is peeled off from the configuration of  FIG. 9 . The glass substrate  100  can be peeled off by laser ablation, for example, by irradiating with a laser beam a boundary between the glass substrate  100  and the second polyimide film  200 . Since adhesion between the polyimide film  200  and the glass substrate  100  is inherently weak, the glass substrate  100  can be relatively easily peeled off from the polyimide film  200 . 
     In the configuration shown in  FIG. 10 , since two polyimide films are formed, there is no need to extremely increase the thickness of each polyimide film, so that a process load is small. In addition, since a barrier film formed of a silicon oxide (SiO) film and a silicon nitride (SiN) film is formed in two layers, it is possible to reduce the influence of moisture or the like on the organic EL film  117  and the like from the outside. Accordingly, it is possible to realize a highly reliable flexible display device having a HAPTIC sensor. If there is no problem in terms of reliability, the second barrier film  201  may be omitted, and a PZT sensor may be directly formed on the second polyimide film  200 . 
     While the above description has been made of an organic EL display device as a display device, the configuration of the present invention can be used in other display devices such as a liquid crystal display device and a micro LED display device. Further, the present invention is applicable to other semiconductor devices used in combination with PZT sensors. In this case, the display areas in Embodiments 1 to 3 can be referred to as active areas. 
     Further, a material of a ferroelectric material other than PZT is also present as a piezoelectric element or a pyroelectric element; the present invention can be similarly applied to a sensor using these materials.