JP2008300630A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress variations in characteristics of a semiconductor element by stabilizing the potential of a light shielding layer arranged on the substrate side of the semiconductor element, relating to a semiconductor device equipped with a plurality of semiconductor elements formed on a substrate. <P>SOLUTION: The semiconductor device comprises a light-transmitting substrate 101, a plurality of semiconductor elements 125 supported by the substrate 101, a plurality of conductive light shielding layers 103 which are of island shape arranged between the substrate 101 and the plurality of semiconductor elements 125, and a light-transmitting conductive film 102 arranged between the substrate 101 and the plurality of semiconductor elements 125. The plurality of island-like light shielding layers 103 are related to at least two semiconductor elements of the plurality of semiconductor elements 125, and are electrically connected to the conductive film 102. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor device including a semiconductor element, a method for manufacturing the same, and a display device including the semiconductor device.

  In recent years, development of semiconductor devices including semiconductor elements such as thin film diodes (TFDs) and thin film transistors (TFTs), and electronic devices having such semiconductor devices has been underway.

  Patent Document 1 discloses an image sensor including an optical sensor unit using TFD and a drive circuit using TFT on the same substrate. Patent Document 2 discloses a liquid crystal display device including an active matrix substrate having a plurality of TFTs as switching elements. Further, Patent Document 3 describes using TFD instead of TFT as a switching element used for an active matrix substrate of a liquid crystal display device. These TFDs and TFTs are usually manufactured using a semiconductor layer formed on a light-transmitting insulating substrate such as a glass substrate.

  In a semiconductor device using a semiconductor element such as a TFD or a TFT, depending on the application or use environment, a semiconductor layer serving as an active region of these semiconductor elements may be provided on the back side of a light-transmitting substrate (a surface on which a semiconductor layer is formed). It is necessary to shield the back side of the semiconductor layer so that light does not enter from the opposite side. For example, when a TFD or TFT is used in a transmissive display device, light from the backlight may pass through the light-transmitting substrate and enter the TFD or TFT semiconductor layer, causing deterioration in element characteristics. There is sex. In particular, if these semiconductor elements are applied to a liquid crystal projector or the like, the intensity of light incident from the back side of the substrate is high, and the element characteristics may be significantly degraded. Therefore, in order to suppress such deterioration of element characteristics, the back side of the semiconductor layer of TFD or TFT is shielded as necessary. Also, when using the TFD as an optical sensor, it is necessary to shield the side opposite to the surface on which light is to be incident on the TFD.

  In order to shield the TFD and TFT semiconductor layers, Patent Document 2 and Patent Document 3 described above disclose a configuration in which a light shielding layer is provided on the back side of the semiconductor layer. In the liquid crystal display device disclosed in Patent Document 2, a plurality of island-shaped conductive light shielding layers are provided on a glass substrate, and a TFT semiconductor layer is formed on each conductive light shielding layer via an insulating film. Has been. As the conductive light shielding layer, a laminated film of a polycrystalline Si film and a WSi film is used. With this configuration, it is possible to prevent light incident on the liquid crystal display device from the back side of the glass substrate from entering the TFT semiconductor layer. Patent Document 3 proposes forming an island-shaped light-shielding layer between a light-transmitting substrate and a TFD semiconductor layer formed on the substrate. A chromium film is used as the light-shielding layer. An example using is shown.

Since the light shielding layer in Patent Document 2 and Patent Document 3 is arranged so that light from the backlight does not enter the semiconductor layer of the semiconductor element, the light shielding layer has a pattern large enough to shield the corresponding semiconductor layer. Yes. Each of these light shielding layers is formed by patterning a conductive film made of a metal material having high light shielding properties.
Japanese Patent Laid-Open No. 6-275808 JP 2003-307749 A JP 2002-303879 A

  However, as a result of studies by the inventors of the present application, a plurality of conductive light shielding layers are provided below a plurality of semiconductor elements such as TFDs and TFTs as in the configurations disclosed in Patent Document 2 and Patent Document 3 described above. And found the following problems.

  According to the configurations disclosed in Patent Document 2 and Patent Document 3, the plurality of light-shielding layers having conductivity are arranged on the substrate with a space therebetween, and thus are in a floating state in terms of potential. For this reason, the potential of each light shielding layer becomes unstable, and as a result, the characteristics of the corresponding semiconductor element may be affected, resulting in variations in element characteristics.

  In particular, when TFD is used as an optical sensor, a reverse bias is applied to TFD and a leak current due to light is captured as a signal. However, if the potential of the light shielding layer of TFD is unstable, the leakage at the time of reverse bias with respect to light The value of current (hereinafter referred to as “photocurrent”) varies greatly, making accurate sensing difficult.

  In addition, in the unpublished patent application (Japanese Patent Application No. 2007-116098), the inventors of the present application formed a pixel switching TFT, a peripheral drive circuit TFT, and a photosensor TFD on the same substrate. It has been proposed to add a sensor function to a conventional display device. In such a display device, it is desirable to provide a light shielding layer below the semiconductor layer serving as the active region of the TFD so that at least the TFD used as the optical sensor reacts only to external light. In particular, in a transmissive liquid crystal display device, a backlight is disposed on the back side of the substrate, so that the TFD does not detect light from the backlight but detects only external light. It is necessary to provide a light shielding layer. Since these light shielding layers are also in a floating state with respect to the potential as described above, there is a possibility of causing variations in the photocurrent characteristics of the TFD.

  The present invention has been made in view of the above problems, and an object of the present invention is to stabilize the potential of the light shielding layer disposed on the substrate side of the semiconductor element in a semiconductor device including a plurality of semiconductor elements formed on the substrate. This is to suppress variation in characteristics of semiconductor elements.

  A semiconductor device according to the present invention includes a light-transmitting substrate, a plurality of semiconductor elements supported by the substrate, and a plurality of conductive islands disposed between the substrate and the plurality of semiconductor elements. A light-shielding layer, and a light-transmitting conductive film disposed between the substrate and the plurality of semiconductor elements, wherein the plurality of island-shaped light-shielding layers include at least two of the plurality of semiconductor elements. It is associated with a semiconductor element and is electrically connected to the conductive film.

  In a preferred embodiment, the at least two semiconductor elements include a plurality of thin film diodes, and each thin film diode includes a semiconductor layer including an n-type region and a p-type region.

  The semiconductor layer of each thin film diode preferably further includes an intrinsic region formed between the n-type region and the p-type region.

  When viewed from the substrate side, each island-shaped light shielding layer is preferably arranged so as to shield at least the intrinsic region of the semiconductor layer of the associated thin film diode.

  In a preferred embodiment, the plurality of semiconductor elements include a plurality of thin film transistors, and each thin film transistor includes a semiconductor layer including a channel region, a source region, and a drain region, and the semiconductor layer of each of the thin film transistors, the substrate, A light shielding layer is not provided between them.

  In one preferred embodiment, the at least two semiconductor elements further include a plurality of thin film transistors, each of the plurality of thin film transistors having a semiconductor layer including a channel region, a source region, and a drain region, and the plurality of islands. A part of the light shielding layer may be disposed between the semiconductor layers of the plurality of thin film transistors and the substrate.

  The semiconductor layers of the plurality of thin film transistors and the semiconductor layers of the plurality of thin film diodes may be crystalline semiconductor layers.

  The plurality of thin film transistors may include an n-channel thin film transistor and a p-channel thin film transistor.

  In a preferred embodiment, the at least two semiconductor elements include a plurality of thin film transistors, and each thin film transistor includes a semiconductor layer including a channel region, a source region, and a drain region, a gate insulating film provided on the semiconductor layer, A gate electrode for controlling the conductivity of the channel region, and when viewed from the substrate side, each island-shaped light shielding layer shields at least the channel region of the semiconductor layer of the associated thin film transistor. Has been placed.

  In a preferred embodiment, each of the plurality of semiconductor elements has an island-shaped semiconductor layer, and when viewed from the substrate side, each island-shaped light-shielding layer is a semiconductor layer of an associated semiconductor element. It arrange | positions so that at least one part may be light-shielded.

  When viewed from the substrate side, each island-shaped light shielding layer may be arranged to shield the semiconductor layer of the associated semiconductor element.

  It is preferable that the plurality of island-shaped light shielding layers have the same potential.

  The conductive film may be formed over the entire surface of the substrate.

  The plurality of island-shaped light shielding layers may be disposed on the conductive film so as to be in contact with the conductive film. Alternatively, the conductive film may be disposed on the plurality of island-shaped light shielding layers so as to be in contact with the plurality of island-shaped light shielding layers.

  The method for manufacturing a semiconductor device according to the present invention includes: (a) a step of forming a light-transmitting conductive film on a light-transmitting substrate; and (b) a plurality of conductive layers on the conductive film. Providing an island-shaped light shielding layer; (c) forming a light-transmitting insulating film on the conductive film and the plurality of island-shaped light shielding layers; and (d) a semiconductor on the insulating film. A step of forming a film, and (e) patterning the semiconductor film to form a plurality of island-like semiconductor layers to be active regions of a semiconductor element, wherein at least two of the plurality of island-like semiconductor layers are formed. Forming one on the plurality of island-shaped light shielding layers.

  In another method of manufacturing a semiconductor device of the present invention, (a) a step of providing a plurality of island-shaped light-shielding layers having conductivity on a light-transmitting substrate; and (b) the substrate and the plurality of light-shielding layers. Forming a light-transmitting conductive film so as to cover the layers; (c) forming a light-transmitting insulating film on the conductive film; and (d) a semiconductor on the insulating film. A step of forming a film, and (e) patterning the semiconductor film to form a plurality of island-shaped semiconductor layers to be active regions of a semiconductor element, wherein at least two of the plurality of island-shaped semiconductor layers are formed On the plurality of island-shaped light shielding layers.

  In a preferred embodiment, the plurality of island-shaped semiconductor layers include a plurality of island-shaped semiconductor layers that become active regions of the thin film diode.

  In a preferred embodiment, the plurality of island-shaped semiconductor layers include a plurality of island-shaped semiconductor layers that become active regions of thin film transistors.

  In a preferred embodiment, the plurality of island-shaped semiconductor layers include a plurality of island-shaped semiconductor layers that serve as active regions of thin film diodes, and a plurality of island-shaped semiconductor layers that serve as active regions of thin film transistors. ) Forming a plurality of island-shaped semiconductor layers serving as active regions of the thin-film diodes on the plurality of island-shaped light-shielding layers, and a plurality of island-shaped semiconductor layers serving as active regions of the thin film transistors, Forming on a region of the surface of the substrate where the plurality of island-shaped light shielding layers are not formed.

  After the step (e), a step (f1) of doping an n-type impurity element into a region that later becomes an n-type region of each island-like semiconductor layer that becomes an active region of the thin-film diode; A step (f2) of doping a p-type impurity element into a region to be a later p-type region out of each island-like semiconductor layer to be an active region may be included.

  In the steps (f1) and (f2), an n-type impurity element is doped between a region doped with an n-type impurity element and a region doped with a p-type impurity element in each island-like semiconductor layer serving as an active region of the thin film diode. The step may be performed so that a region where both the p-type impurity element and the p-type impurity element are not doped remains.

  The n-type impurity element and the p-type impurity element formed between the region doped with the n-type impurity element and the region doped with the p-type impurity element in each island-like semiconductor layer serving as an active region of the thin-film diode. The region where both are not doped is preferably disposed so as to be shielded from light by the corresponding island-shaped light shielding layer as viewed from the substrate side.

  In a preferred embodiment, the plurality of island-shaped semiconductor layers further include a plurality of island-shaped semiconductor layers that become active regions of thin film transistors, and after the step (e), (g1) a semiconductor that becomes active regions of the thin film transistors Forming a gate insulating film on the layer; (g2) forming a gate electrode on the gate insulating film; and (g3) forming a source region and a drain region later in the semiconductor layer of the thin film transistor. A step of doping the region with an n-type impurity element, and the step (g3) is performed simultaneously with the step (f1).

  In a preferred embodiment, after the step (e), (g1) a step of forming a gate insulating film on a semiconductor layer which becomes an active region of the thin film transistor; and (g2) a gate electrode on the gate insulating film. And (g4) a step of doping a p-type impurity element into a region to be a source region and a drain region later in the semiconductor layer to be an active region of the thin film transistor, and the step (g4) includes , Simultaneously with the step (f2).

  In a preferred embodiment, the plurality of island-like semiconductor layers further include a semiconductor layer that becomes an active region of an n-type thin film transistor and a semiconductor layer that becomes an active region of a p-type thin film transistor, and after the step (e), (g1 ) A step of forming a gate insulating film on the semiconductor layer which becomes an active region of the n-type thin film transistor and the p-type thin film transistor; (g2) a step of forming a gate electrode on the gate insulating film; and (g5) the n A step of doping an n-type impurity element into a region to be a later source region and a drain region among semiconductor layers to be an active region of the p-type thin film transistor, and (g6) of a semiconductor layer to be an active region of the p-type thin film transistor, A step of doping a p-type impurity element into a region to be a source region and a drain region later, and the step (g5 The said step (f1) at the same time carried out, the step (g6) is the step (f2) at the same time is carried out.

  The semiconductor device of the present invention is a semiconductor device manufactured by any one of the manufacturing methods described above.

  An electronic device of the present invention is an electronic device formed by any of the manufacturing methods described above, includes any of the semiconductor devices described above, and includes a display unit.

  Another electronic device of the present invention includes any one of the semiconductor devices described above and includes an optical sensor unit.

  The semiconductor device according to any of the above may be included, and a display unit and a photosensor unit may be provided.

  The plurality of semiconductor elements may include a thin film transistor and a thin film diode, the display unit may include the thin film transistor, and the optical sensor unit may include the thin film diode.

  The optical sensor unit may be an ambient sensor for adjusting the luminance of the display unit. Alternatively, the optical sensor unit may be a touch panel sensor of the display unit.

  The display device of the present invention is a display device comprising a display region having a plurality of display units and a frame region located around the display region, further comprising an optical sensor unit including a plurality of thin film diodes, Each display unit includes an electrode and a thin film transistor connected to the electrode, and the thin film transistor and the plurality of thin film diodes are formed over the same substrate having translucency, and each of the plurality of thin film diodes is , An n-type region, a p-type region, and an intrinsic region provided between the n-type region and the p-type region, and disposed between the plurality of thin film diodes and the substrate. A plurality of light-shielding layers having electrical conductivity, and a light-transmissive conductive film disposed between the plurality of thin-film diodes and the substrate, wherein the plurality of light-shielding layers are formed from the substrate side. When in the at least the one of the semiconductor layers of a plurality of thin-film diode are arranged so as to shield the intrinsic region, and is electrically connected to the conductive film.

  The display device may further include a backlight.

  In a preferred embodiment, the optical sensor unit includes a plurality of photosensor units, and the plurality of photosensor units are arranged in the display area corresponding to each display unit or a set of two or more display units, respectively. Yes.

  In a preferred embodiment, the backlight has a backlight control circuit that adjusts the luminance of light emitted from the backlight, and the light sensor unit is disposed in the frame area, and the illuminance of external light Is generated and output to the backlight control circuit.

  According to the present invention, in a semiconductor device having a plurality of semiconductor elements formed on a light-transmitting substrate, the light shielding layer is provided between the semiconductor element and the substrate. It is possible to suppress deterioration of element characteristics due to the incidence of. Moreover, since each light shielding layer is electrically connected to the light-transmitting conductive film, the potential of the light shielding layer between the semiconductor elements can be stabilized, and as a result, variations in characteristics of the semiconductor elements can be reduced.

  In particular, when a semiconductor element is used as an optical sensor, more accurate sensing is possible by stabilizing the potential of the light shielding layer, and thus a semiconductor device having favorable characteristics as an optical sensor can be obtained.

  The present invention is suitably used for a transmissive display device with a sensor function, for example. For example, when the present invention is applied to a transmissive liquid crystal display device including a TFT used for a driving circuit and a TFT for switching a pixel electrode and a TFD used as an optical sensor, the aperture ratio is not reduced. This is advantageous because the photocurrent characteristics of the photosensor can be enhanced. At this time, if the pixel switching TFT, the peripheral drive circuit TFT, and the optical sensor TFD are simultaneously formed on the same substrate, there are significant cost advantages such as a reduction in the number of parts, and the manufacturing process is complicated. Therefore, the manufacturing cost can be reduced and the yield can be improved.

  Hereinafter, a preferred embodiment of a semiconductor device according to the present invention will be described.

  A semiconductor device according to an embodiment of the present invention includes a plurality of semiconductor elements formed on a substrate having optical transparency. Between the substrate and the plurality of semiconductor elements, a plurality of island-shaped light-shielding layers having conductivity and a light-transmitting conductive film are provided, and the plurality of island-shaped light-shielding layers are formed of a conductive film. They are electrically connected to each other. The plurality of island-shaped light shielding layers are associated with at least two of the semiconductor elements. More specifically, each of the semiconductor elements has a semiconductor layer serving as an active region, and the island-shaped light shielding layer is disposed so as to shield at least a part of the associated semiconductor layer.

  The plurality of semiconductor elements may include a TFD having a semiconductor layer including at least an n-type region and a p-type region. Or a semiconductor layer formed over a light-transmitting substrate and including a channel region, a source region, and a drain region; a gate insulating film provided over the semiconductor layer; and a gate electrode that controls conductivity of the channel region; A TFT having the following may be included. Alternatively, both TFD and TFT may be included. Further, the light shielding layer may be provided below all the semiconductor elements, or may be provided only below some of the semiconductor elements depending on the type and application of the semiconductor elements.

  According to the present embodiment, the island-shaped light shielding layers that have been floating in the prior art are formed of a conductive material and are electrically connected by a light-transmitting conductive film. Thereby, since the electric potential of each light shielding layer is made constant, variation in characteristics of semiconductor elements can be reduced, and stabilization of element characteristics can be realized.

  Hereinafter, the results of comparing the characteristics of the semiconductor element of the present embodiment and the conventional semiconductor element will be described using TFD as an example with reference to the drawings.

  11A and 11B are diagrams showing the photocurrent characteristics of a conventional TFD. FIG. 11A shows data on the TFD application voltage dependence of the leak current value (photocurrent value) that flows when a reverse bias is applied to the TFD under an illuminance of 10000 lx. It was obtained by point measurement. The negative voltage range corresponds to the reverse bias. FIG. 11B shows the voltage dependence with the standard deviation obtained from the variation and the 3σ / average value as the variation index. Table 1 shows the values of leakage current values (average value, maximum value and minimum value), standard deviation, and variation index when the applied voltage is -5V.

  The reason why the value when the applied voltage is −5 V is selected is as follows. When TFD is actually used as an optical sensor, about −2V to −8V is appropriate as a voltage applied to TFD. Therefore, the inventors of the present application have studied for the purpose of reducing the variation when the applied voltage is -5V.

  On the other hand, the photocurrent characteristics of the TFD obtained by this embodiment are shown in FIGS. Similar to FIGS. 11A and 11B, FIG. 12A shows a TFD applied voltage of a leak current value (photocurrent value) that flows when a reverse bias is applied to the TFD under an illuminance of 10000 lx. It is a figure which shows the measurement result of dependence, and FIG.12 (B) is a figure which shows the applied voltage dependence with respect to variation parameter | index 3σ / average. Table 2 shows values of leakage current values (average value, maximum value and minimum value), standard deviation, and variation index when the applied voltage is -5V.

  The number of data measurement points is 50, which is the same as in FIG. Here, comparing the results shown in FIG. 11 and Table 1 with the results shown in FIG. 12 and Table 2, the results shown in FIG. 12 and Table 2 remarkably improve the variation in photocurrent during reverse bias. You can see that In particular, the 3σ / average variation index when the applied voltage is −5 V is reduced from 61.1% to 16.7%, which is 1/3 or less.

  Therefore, it can be confirmed that the variation of the TFD characteristics can be significantly reduced by the configuration of this embodiment.

  In addition, the semiconductor device of this embodiment may include a plurality of TFDs and a plurality of TFTs formed on a light-transmitting substrate. That is, not only the TFD but also the TFT can be formed on the same substrate. As an example of the semiconductor device having such a configuration, a transmissive liquid crystal display device having an optical sensing function in the screen can be considered. For example, an active matrix display device including a pixel switching TFT and a driving circuit TFT can be provided with a photosensor portion using TFD. In this case, it is preferable to form a light shielding layer at least between the TFD and the substrate.

  When this embodiment is applied to a transmissive display device, there are the following advantages. When a TFD having an electrically independent light-shielding layer as in the past is applied to a transmissive display device, the TFD potential is unstable as described above, and it is difficult to perform accurate sensing by TFD. . Therefore, in order to electrically connect and stabilize the light shielding layers of each TFD, it is conceivable to connect the light shielding layers by wiring. However, the light shielding layers are connected by wiring within the display area of the transmissive liquid crystal display device. When the light shielding layer is provided, the aperture ratio is reduced by the wiring, and the luminance of display is reduced. In addition, wiring that is not necessary in the conventional display device is newly formed, which complicates the manufacturing process, increases the manufacturing cost, and decreases the yield of non-defective products.

  On the other hand, in the present embodiment, a plurality of light shielding layers formed on the back side of the TFD can be electrically connected without newly providing a light shielding metal wiring, so that the TFD is secured while ensuring a high aperture ratio. The variation in the photocurrent characteristics can be reduced. In addition, a light-transmitting conductive film may be formed over the entire substrate surface, and it is not necessary to add a patterning process. Therefore, the potential of the light shielding layer can be stabilized without complicating the manufacturing process. In addition to the pixel switching TFT and the peripheral drive circuit TFT, an optical sensor TFD can be formed simultaneously on an active matrix substrate used in a liquid crystal display device having a transmissive structure, which greatly reduces the number of components. There is cost merit. Further, in manufacturing these two types of semiconductor elements, a semiconductor including TFTs and TFDs having optimum characteristics for each semiconductor element in a low-cost and high-yield manufacturing process without complicating the manufacturing process. A device is obtained.

  In the present embodiment, it is preferable that the semiconductor layer of the semiconductor element is disposed inside the outline of the island-shaped light shielding layer as viewed from above the substrate. In other words, when viewed from the substrate side, the semiconductor layer of the semiconductor element is preferably disposed in a region shielded by the light shielding layer. With such an arrangement, light irradiated from the back surface of the substrate can be sufficiently prevented from entering the semiconductor layer of the thin film diode.

When a TFD is provided as a semiconductor element, the semiconductor layer of each TFD preferably has a structure including at least an n-type region, a p-type region, and an intrinsic (i-type) region sandwiched between them. With such a structure, it is possible to generate a photo-induced current not only in the junction but also in the intrinsic region, and greatly enhance the function as an optical sensor. In this case, it is desirable that at least an intrinsic (i-type) region of the TFD semiconductor layer is disposed inside the outline of the island-shaped light shielding layer as viewed from above the substrate. In other words, when viewed from the substrate side, it is preferable that at least the intrinsic region of the TFD semiconductor layer is disposed in a region shielded by the light shielding layer. As a result, the junction between the intrinsic region, which is a source for generating a photocurrent, and the n ⁺ region and the p ⁺ region is shielded from light, so that it functions as a light shielding layer at a necessary level.

  In this embodiment, all the light shielding layers formed on the substrate have the same potential. In addition, since the light-transmitting conductive film is formed over the entire surface of the substrate, the potential is stabilized in all semiconductor elements (eg, TFD) on the substrate, and variations in element characteristics are reduced. Further, since the light-transmitting conductive film is left on the entire surface of the substrate without patterning, a semiconductor device having a high-performance semiconductor element can be obtained by a simple manufacturing process without adding a patterning process or the like. .

  The light-transmitting conductive film formed on the entire surface of the substrate prevents invasion against electrostatic breakdown (ESD) such as peeling charging from the back side of the substrate in the manufacturing process of semiconductor elements such as TFD and TFT. It also plays a role as an electric field shield layer and has a great effect in suppressing ESD. As a result, the yield of good products in the manufacturing process can be greatly improved.

  In JP-A-7-146490, a light-transmitting conductive film is used as an antistatic layer so as to wrap a glass substrate for the purpose of preventing ESD in the TFT manufacturing process due to the thinning of the gate insulating film. It has been proposed to form. However, this document does not describe any formation of an island-shaped light shielding layer between the TFT and the glass substrate. Furthermore, the surface of the antistatic layer is completely covered with an insulating film and is not electrically connected to other conductive layers. Therefore, it does not teach or suggest that a conductive light shielding layer is formed so as to be in contact with the antistatic layer, and that the island-shaped light shielding layer is electrically connected by the antistatic layer.

  Here, the light-transmitting conductive film only needs to be electrically connected to the light shielding layer of each semiconductor element, and may be formed immediately below the light shielding layer (between the light shielding layer and the substrate). Alternatively, it may be formed immediately above the light shielding layer (between the light shielding layer and the semiconductor layer). Thus, it is advantageous to form the light shielding layer and the light-transmitting conductive film so as to directly overlap each other because the conductive film and the light shielding layer of each semiconductor element can be connected more simply and reliably.

  When the TFD and the TFT are formed on the same substrate, it is preferable to provide a light shielding layer at least below the TFD semiconductor layer, and the light shielding layer may or may not be provided below the TFT semiconductor layer. Good. However, when applied to a projector, it is preferable to provide a light shielding layer below the semiconductor layer of the TFT. In that case, the light shielding layer is arranged so as to shield at least the channel region, preferably the channel region and the LDD region, of the semiconductor layer of the TFT.

  The TFD semiconductor layer and the TFT semiconductor layer are preferably formed using semiconductor films having the same crystallinity. In particular, a TFT requires a high driving capability, that is, a high field-effect mobility. Therefore, the TFT semiconductor layer is preferably a high-quality crystalline semiconductor layer.

  However, in the ELA crystallization method generally used, that is, in the method of crystallization by irradiating a semiconductor layer with laser light and melting and solidifying, solidification starts from the lower surface side of the crystal due to the escape of heat toward the substrate, Crystallization takes place. The heat escape at this time varies greatly depending on the structure of the lower layer of the semiconductor layer, and the resulting crystal state also varies greatly. The smaller the escape of latent heat, the more slowly it solidifies and a crystalline semiconductor film having high crystallinity is obtained. On the contrary, if the escape of latent heat is large, it becomes solid at a high speed, resulting in a low crystalline crystalline semiconductor film with small individual crystal grains and many crystal defects.

  Here, as the light shielding layer, a film made of a metal material having a light shielding property is preferably used, but since the heat capacity and thermal conductivity of such a light shielding layer are high, in the semiconductor layer on the light shielding layer, During melting and solidification by laser irradiation, the escape of latent heat in the direction of the substrate is large, and a semiconductor layer having high crystallinity cannot be obtained as compared with a semiconductor layer on a region without a light shielding layer. Therefore, a TFT that requires a crystalline semiconductor layer having high crystallinity has a configuration in which there is no light-shielding layer below the semiconductor layer, and a TFD that requires a crystalline semiconductor layer with high photosensitivity is a semiconductor layer. It is preferable to have a structure in which a light shielding layer is provided below. Thus, a TFT and a TFD formed on the same substrate both have a crystalline semiconductor film having an optimal crystal state for each semiconductor element, and a semiconductor device including a TFT and a TFD having good characteristics. realizable.

  Further, the semiconductor device of this embodiment may include an n-channel thin film transistor and a p-channel thin film transistor in addition to the TFD. In this case, since the doping step and the like can be shared among the processes for manufacturing the TFD and the TFT, it is possible to manufacture a plurality of types of semiconductor elements on the same substrate by an efficient and simple process.

  As a method for manufacturing a semiconductor device according to an embodiment of the present invention, a step of forming a light-transmitting conductive film on a light-transmitting substrate and a plurality of conductive properties on the light-transmitting conductive film A step of providing an island-shaped light-shielding layer including: a step of forming a light-transmitting conductive film and a plurality of light-shielding layers; a step of forming a light-transmitting insulating film; and a step of forming a semiconductor film on the insulating film And a step of patterning the semiconductor film and forming a plurality of island-like semiconductor layers serving as active regions of the semiconductor element over a region at least partially overlapping the plurality of light-shielding layers. Alternatively, a step of providing a plurality of conductive island-shaped light shielding layers over a light transmissive substrate, and a step of forming a light transmissive conductive film so as to cover the substrate and the plurality of light shielding layers A step of forming a light-transmitting insulating film on the light-transmitting conductive film, a step of forming a semiconductor film on the insulating film, and patterning the semiconductor film, at least a part of which is a plurality of light-shielding layers And a step of forming a plurality of island-like semiconductor layers on a region overlapping with the substrate. The plurality of island-shaped semiconductor layers may include an island-shaped semiconductor layer serving as an active region of the thin film diode, or may include an island-shaped semiconductor layer serving as an active region of the thin film transistor. Further, it may include both an island-shaped semiconductor layer serving as an active region of a thin film diode and an island-shaped semiconductor layer serving as an active region of a thin film transistor.

  Thereby, since the light shielding layer and the light transmissive conductive film can be directly overlapped, the respective island-shaped light shielding layers and the light transmissive conductive film can be electrically connected most easily. Therefore, the potential of each light shielding layer in all the semiconductor elements on the substrate is the same potential. In addition, since the light-transmitting conductive film is formed over the entire surface of the substrate, the potential of the light-shielding layer in all the semiconductor elements on the substrate is stabilized, and as a result, variation in characteristics of the semiconductor elements is reduced. Furthermore, since the light-transmitting conductive film is left on the entire surface of the substrate without patterning, the number of patterning steps and the like is not increased, and the semiconductor device of the present invention can be manufactured through a simple manufacturing process.

  In addition, as a method for manufacturing a semiconductor device according to an embodiment of the present invention, a step of forming a light-transmitting conductive film on a light-transmitting substrate, and a plurality of light-transmitting conductive films on the light-transmitting conductive film A step of providing an island-shaped light-shielding layer having conductivity, a step of forming a light-transmitting conductive film and a plurality of light-shielding layers on the light-transmitting conductive film, and forming a semiconductor film on the insulating film And a step of patterning the semiconductor film, forming a plurality of island-shaped semiconductor layers serving as active regions of the thin-film diode on a region at least partially overlapping the plurality of light-shielding layers, and on a region where the light-shielding layer does not exist, Forming a plurality of island-like semiconductor layers to be active regions of the thin film transistor. Alternatively, a step of providing a plurality of conductive island-shaped light shielding layers over a light transmissive substrate, and a step of forming a light transmissive conductive film so as to cover the substrate and the plurality of light shielding layers A step of forming a light-transmitting insulating film on the light-transmitting conductive film, a step of forming a semiconductor film on the insulating film, and patterning the semiconductor film, at least a part of which is a plurality of light-shielding layers Forming a plurality of island-shaped semiconductor layers serving as active regions of the thin-film diode over a region overlapping with the light-emitting layer, and forming a plurality of island-shaped semiconductor layers serving as active regions of the thin film transistor over a region where the light-shielding layer does not exist. Include.

  As a result, the light shielding layer and the light transmissive conductive film can be directly overlapped with each other, so that each island-shaped light shielding layer and the light transmissive conductive film are electrically connected most easily. The potentials of the respective light shielding layers in all the thin film diodes formed on the substrate are the same, and the light-transmitting conductive film is formed over the entire surface of the substrate. Therefore, the potential is stabilized by the TFD of the entire substrate, and variations in photocurrent characteristics are reduced. Furthermore, since the light-transmitting conductive film is left on the entire surface of the substrate without patterning, the number of patterning steps and the like is not increased, and the semiconductor device of this embodiment can be manufactured through a simple manufacturing process.

  Further, by using this embodiment, a TFD for a photosensor can be formed simultaneously with a pixel switching TFT and a peripheral drive circuit TFT in an active matrix substrate or the like used for a liquid crystal display device. Since it can be simultaneously formed on the same substrate, there are significant cost advantages such as a reduction in the number of components. Further, the light-transmitting conductive film on the entire surface of the substrate also serves as an electric field shielding layer for preventing the penetration of ESD such as peeling charging from the back side of the substrate in the manufacturing process of the TFD and TFT. It has a great effect on suppression. As a result, the yield of good products in the manufacturing process can be greatly improved.

  Further, in the above manufacturing method, the step of forming the semiconductor film over the insulating film includes a step of forming an amorphous semiconductor film and a step of crystallizing the amorphous semiconductor film by irradiating the amorphous semiconductor film with laser light. It is preferable to do. In addition, the step of forming the semiconductor film over the insulating film includes the steps of forming an amorphous semiconductor film, adding a catalyst element that promotes crystallization to the amorphous semiconductor film, and performing heat treatment. And a step of crystallizing at least a part thereof. A thin film transistor requires high driving capability, that is, high field-effect mobility, and thus a high-quality crystalline semiconductor layer is required as the semiconductor layer. By using the method as described above, a high-quality crystalline semiconductor layer can be obtained.

  One of the simplest methods for obtaining a good crystalline semiconductor layer on a glass substrate is a method of crystallizing an amorphous semiconductor layer by irradiating it with laser light. As another method, a method in which a metal element having an action of promoting crystallization is added to the amorphous semiconductor layer and then subjected to heat treatment for crystallization can be used. In this case, a good crystalline semiconductor film with uniform crystal orientation can be obtained as compared with a crystalline semiconductor film crystallized only by general laser irradiation. In the case of this method, laser light may be irradiated to further increase the crystallinity. As the catalyst element at this time, one or more elements selected from Ni, Co, Sn, Pb, Pd, Fe, and Cu can be used. One or more kinds of elements selected from these have the effect of promoting the crystallization of the amorphous semiconductor film in a small amount. Among them, the most remarkable effect can be obtained particularly when Ni is used. In this way, the optimum element characteristics required for each of the TFT and the TFD can be realized simultaneously using the same semiconductor layer.

  Furthermore, in the present embodiment, after the step of forming a plurality of island-shaped semiconductor layers serving as active regions of the thin-film diodes by the above-described method, A step of doping an n-type impurity element into a region to be a p-type region, and a step of doping a p-type impurity element into a region to be a p-type region later of a plurality of island-like semiconductor layers to be active regions of a thin film diode Including. In this manner, the n-type impurity region and the p-type impurity region are formed in the semiconductor layer that becomes the active region of the thin film diode, thereby completing the TFD.

  At this time, a step of doping an n-type impurity element into a region to be a later n-type region of a plurality of island-shaped semiconductor layers to be an active region of the thin-film diode and a plurality of island-shaped semiconductors to be an active region of the thin-film diode A step of doping a p-type impurity element into a region to be a later p-type region of the layer means that a region doped with an n-type impurity element and a p-type impurity in a plurality of island-like semiconductor layers to be active regions of a thin film transistor It is desirable that the step be performed so that a region not doped with both the n-type impurity element and the p-type impurity element remains between the region doped with the element. As a result, the semiconductor layer serving as the active region of these thin film diodes has a structure including at least an n-type region, a p-type region, and an intrinsic (i-type) region sandwiched between them. Such a TFD structure can generate a photo-induced current not only in the junction between the n-type region and the p-type region but also in the intrinsic region, so that the function as an optical sensor can be enhanced.

Here, a region formed between the region doped with the n-type impurity element and the region doped with the p-type impurity element and not doped with both the n-type impurity element and the p-type impurity element is seen from above the substrate. Thus, it is preferably formed at least inside the region where the island-shaped light shielding layer exists. As a result, the intrinsic (i-type) region of the semiconductor layer of the thin film diode is arranged in the region shielded by the island-shaped light shielding layer with respect to the light incident on the semiconductor device from the back side of the substrate. Thus, it is possible to reliably shield the intrinsic region, which is a source of generation of light, and the junction between the n ⁺ region and the p ⁺ region.

  In addition to the above embodiment, at least after the step of forming a plurality of island-shaped semiconductor layers to be active regions of the thin-film diode and forming the plurality of island-shaped semiconductor layers to be active regions of the thin-film transistors, the active regions of the thin-film transistors Forming a gate insulating film on the plurality of island-shaped semiconductor layers to be, forming a gate electrode on the gate insulating film on the plurality of island-shaped semiconductor layers serving as an active region of the thin film transistor, and activating the thin film transistor A step of doping an n-type impurity element into a region to be a later source region and a drain region of a plurality of island-like semiconductor layers to be a region, and a plurality of island-like semiconductor layers to be an active region of a thin film transistor, The step of doping an n-type impurity element into a region to be a source region and a drain region later includes a plurality of steps to be an active region of a thin film diode. Of the island-like semiconductor layer, a step of doping the n-type impurity element in the region to be the n-type region after may be performed simultaneously.

  Thus, an n-type or p-type impurity region to be a source region and a drain region is formed in the semiconductor layer that is an active region of the thin film transistor, and an n-type impurity region is to be formed in the semiconductor layer that is an active region of the thin film diode. A p-type impurity region can be formed, and the TFD and the TFT can be manufactured on the same substrate. At this time, if the doping process for forming the source region and the drain region of the n-channel TFT and the doping process for forming the n-type impurity region of the TFD are performed as the same process, the manufacturing process can be simplified.

  Alternatively, after forming the plurality of island-shaped semiconductor layers serving as the active region of the thin film diode and forming the plurality of island-shaped semiconductor layers serving as the active region of the thin film transistor, at least a plurality of island-shaped semiconductor layers serving as the active region of the thin film transistor Forming a gate insulating film on the semiconductor layer; forming a gate electrode on the gate insulating film on the plurality of island-shaped semiconductor layers to be active regions of the thin film transistor; and a plurality of islands to be the active region of the thin film transistor A step of doping a p-type impurity element into a region to be a later source region and a drain region of the thin semiconductor layer, and a later source region of the plurality of island-like semiconductor layers to be active regions of the thin film transistor The step of doping the region that becomes the drain region with the p-type impurity element includes the steps of: A step of doping a p-type impurity element in a region to be a p-type region after may be performed simultaneously.

  As a result, the doping process for forming the source region and the drain region of the p-channel TFT and the doping process for forming the p-type impurity region of the TFD can be performed as the same process, thereby simplifying the manufacturing process. it can.

  Furthermore, after forming the plurality of island-shaped semiconductor layers serving as the active region of the thin film transistor and forming the plurality of island-shaped semiconductor layers serving as the active region of the thin film transistor, at least a plurality of islands serving as the active region of the thin film transistor are formed. A step of forming a gate insulating film on the thin semiconductor layer, a step of forming a gate electrode on the gate insulating film on the plurality of island-shaped semiconductor layers to be active regions of the thin film transistor, and an n-channel type later in the thin film transistor A step of doping an n-type impurity element into a region to be a later source region and a drain region of a plurality of island-shaped semiconductor layers to be an active region of the thin film transistor, and a plurality of later to be an active region of a p-channel thin film transistor among the thin film transistors In the island-shaped semiconductor layer, a p-type impurity element is doped in a region to be a source region and a drain region later. A step of doping an n-type impurity element into a region to be a later source region and a drain region of a plurality of island-like semiconductor layers to be active regions of the n-channel thin film transistor. A plurality of island-shaped semiconductor layers which are simultaneously formed in the step of doping an n-type impurity element into a region to be a subsequent n-type region of the plurality of island-shaped semiconductor layers to be an active region and serve as an active region of the p-channel thin film transistor The step of doping p-type impurity elements into the regions that will later become the source region and the drain region is performed by the step of doping p-type impurities into the regions that become the later p-type regions of the plurality of island-like semiconductor layers that become the active regions of the thin film diode It may be performed simultaneously with the element doping step.

  When a TFT circuit having a CMOS structure or the like is formed by the above method, a doping process for forming a source region and a drain region of the n-channel TFT and a doping process for forming an n-type impurity region of the TFD are performed. In addition to performing the same process, the doping process for forming the source and drain regions of the p-channel TFT and the doping process for forming the p-type impurity region of the TFD can be performed as the same process. The manufacturing process can be greatly simplified.

  By using the above embodiments, a TFT and a TFD formed on the same substrate, both of which have TFTs and TFDs having optimum characteristics for each semiconductor element, can be manufactured without increasing the manufacturing process. It can be provided in a low-cost and high-yield manufacturing process.

(First embodiment)
The first embodiment of the present invention will be described below with reference to FIG. Here, a method for manufacturing a plurality of TFDs on an insulating substrate such as a glass substrate will be described. FIG. 1 is a cross-sectional view showing a manufacturing process of the thin film diode 125, and the manufacturing process sequentially proceeds in the order of (A) → (H).

  First, as illustrated in FIG. 1A, a light-transmitting conductive film 102 and a plurality of island-shaped light-shielding layers 103 are formed on the surface of an insulating substrate 101.

  As the substrate 101, a low alkali glass substrate or a quartz substrate can be used. In this embodiment, a low alkali glass substrate is used. In this case, heat treatment may be performed in advance at a temperature lower by about 10 to 20 ° C. than the glass strain point.

  As the light-transmitting conductive film 102, an ITO (indium tin oxide) film, an IZO (indium zinc oxide) film, or the like can be used. In this embodiment, an ITO film having a thickness of 70 nm is used. Note that when the thickness of the conductive film 102 is 10 nm or more, a plurality of light-blocking layers formed so as to be in contact with the conductive film 102 can be more reliably electrically connected. On the other hand, since the transmittance decreases when the conductive film 102 is too thick, the thickness of the conductive film 102 is preferably 200 nm or less. More preferably, it is 20 nm or more and 150 nm or less.

  The light shielding layer 103 is disposed so as to function as a light shielding layer for shielding light from the back surface direction of the TFD in the subsequent final product. As the light shielding layer 103, a metal film, a silicon film, or the like can be used, but it is desirable to use a metal film in consideration of light shielding properties. The material of the metal film is preferably tantalum (Ta), tungsten (W), molybdenum (Mo) or the like, which is a refractory metal, in consideration of heat treatment in a later manufacturing process. In the present embodiment, the Mo film is formed by sputtering and patterned to form the light shielding layer 103 having a thickness of, for example, 100 nm. Note that the thickness of the light shielding layer 103 is preferably 30 nm or more in order to more reliably shield the semiconductor layer, while the thickness of the light shielding layer 103 is 300 nm in order to suppress the disconnection of wiring caused by the step caused by the light shielding layer 103. The following is preferable. More preferably, it is 50 nm or more and 200 nm or less.

  Next, as shown in FIG. 1B, in order to prevent diffusion of impurities from the substrate 101, base films 104 and 105 such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film are formed and non-coated thereon. A silicon film (amorphous silicon film) 106 having a crystalline structure is formed.

In the present embodiment, for example, a silicon oxynitride film made from a material gas of SiH ₄ , NH ₃ , and N ₂ O is formed as a lower first base film 104 by a plasma CVD method. As the underlying film 105, a silicon oxide film was formed by a plasma CVD method using SiH ₄ and N ₂ O as material gases. The thickness of the silicon oxynitride film that is the first base film 104 is 30 to 200 nm, for example, 100 nm, and the thickness of the silicon oxide film that is the second base film 105 is 30 to 200 nm, for example, 100 nm. In this embodiment, a two-layer base film is used. However, for example, a single layer of a silicon oxide film is not a problem.

  The amorphous silicon film 106 is formed by a known method such as a plasma CVD method or a sputtering method. The thickness of the amorphous silicon film 106 is preferably 20 to 150 nm, more preferably 30 to 80 nm. In the present embodiment, the amorphous silicon film 106 having a thickness of 50 nm is formed by plasma CVD. In addition, since the base films 104 and 105 and the amorphous silicon film 106 can be formed by the same film formation method, they may be formed continuously. In this case, after the base film is formed, it is possible to prevent contamination of the surface by not exposing it to the air atmosphere, and it is possible to reduce variation in characteristics and threshold voltage of the TFT to be manufactured.

Subsequently, as shown in FIG. 1C, the amorphous silicon film 106 is irradiated with laser light 107 to crystallize the amorphous silicon film 106 to obtain a crystalline silicon film 106a. As the laser light, a XeCl excimer laser (wavelength 308 nm, pulse width 40 nsec) or a KrF excimer laser (wavelength 248 nm) can be applied. The beam size of the laser light is formed to be a long shape on the surface of the substrate 101, and the entire surface of the substrate is crystallized by sequentially scanning in a direction perpendicular to the long direction. At this time, by scanning so that a part of the beams overlap, laser irradiation is performed a plurality of times at any one point of the amorphous silicon film 106, and the uniformity can be improved. In the present embodiment, conditions are set so that irradiation is performed about 10 to 30 times at an arbitrary point of the amorphous silicon film 106. The energy density was set to be 200~450mJ / cm ^2, for example, 350 mJ / cm ^2.

  Thereby, the amorphous silicon film 106 is instantaneously melted and crystallized in the process of solidifying. At this time, a region of the amorphous silicon 106 located on the light shielding layer 103 has a faster heat escape and a higher solidification rate than a region not located on the light shielding layer 103. Accordingly, the region located on the light shielding layer 103 has lower crystallinity than the region not located on the light shielding layer 103.

Thereafter, as shown in FIG. 1D, an unnecessary region of the crystalline silicon film 106a is removed and element isolation is performed to form an island that becomes an active region (n ⁺ / p ⁺ region, intrinsic region) of the thin film diode. A semiconductor layer 108d is formed.

  Subsequently, as illustrated in FIG. 1E, an insulating film 109 is formed to cover the island-shaped semiconductor layers 108d. As the insulating film 109, a silicon oxide film having a thickness of 20 to 150 nm is preferably formed. Here, a silicon oxide film having a thickness of 100 nm is formed.

Next, as shown in FIG. 1F, a mask 111 made of a resist is formed over the insulating film 109 so as to cover a part of the island-shaped semiconductor layer 108d to be an active region of the TFD later. In this state, the entire surface of the substrate 101 is ion-doped with an n-type impurity (phosphorus) 112. At this time, ion doping of the phosphorus 112 is performed so as to pass through the insulating film 109 and be implanted into the semiconductor layer 108d. Through this step, phosphorus 112 is implanted into a region exposed from the resist mask 111 in the TFD semiconductor layer 108d. The region covered by the mask 111 is not doped with phosphorus 112. As a result, the region in which the phosphorus 112 is implanted in the TFD semiconductor layer 108d becomes the later TFD n ⁺ region 114.

Next, after removing the resist 111 used as a mask in the previous step, as shown in FIG. 1G, an insulating film is formed so as to cover a part of the island-shaped semiconductor layer 108d to be an active region of the thin film diode later. A mask 116 made of resist is formed on 109. In this state, the entire surface of the substrate 101 is ion-doped with p-type impurities (boron) 117. At this time, ion doping of boron 117 is performed through the insulating film 109 and implanted into the semiconductor layer 108d. By this step, boron 117 is implanted into a region exposed from the resist mask 116 in the semiconductor layer 108d which becomes an active region of the thin film diode. The region covered by the mask 116 is not doped with boron 117. As a result, the region into which boron 117 is implanted in the semiconductor layer 108d that becomes the active region of the thin film diode becomes the p ⁺ region 118 of the later TFD. In addition, a region of the semiconductor layer 108d where boron 117 is not implanted in this step and phosphorus 112 is not implanted in the previous step is a later intrinsic region 119.

Thereafter, after removing the resist 116 used as a mask in the previous step, this is heat-treated in an inert atmosphere, for example, in a nitrogen atmosphere. By this heat treatment, in the n ⁺ region 114 and the p ⁺ region 118 of the TFD, doping damage such as crystal defects generated at the time of doping is recovered, and phosphorus and boron doped therein are activated. Thereby, the resistance of the n ⁺ region 114 and the p ⁺ region 118 of the TFD can be reduced. As the heat treatment at this time, a general heating furnace may be used, but it is preferable to use RTA (Rapid Thermal Annealing). In particular, a system in which high temperature inert gas is blown onto the substrate surface and the temperature is raised and lowered instantaneously is suitable.

  Subsequently, as shown in FIG. 1H, a silicon oxide film or a silicon nitride film is formed as an interlayer insulating film. In this embodiment, an interlayer insulating film having a two-layer structure of a silicon nitride film 120 and a silicon oxide film 121 is formed. Thereafter, contact holes are formed in these films 120 and 121, and TFD electrodes / wirings 123 are formed of a metal material.

  Finally, annealing is performed at 350 to 450 ° C. in a nitrogen atmosphere or a hydrogen mixed atmosphere at 1 atm to complete the thin film diode 125. If necessary, a protective film made of a silicon nitride film or the like may be provided on the thin film diode 125 for the purpose of protecting the thin film diode 125.

  According to the above embodiment, a high-performance optical sensor TFD with small variations in photocurrent characteristics can be obtained on a substrate having optical transparency such as glass. Note that although FIG. 1 illustrates a method of manufacturing two TFDs for simplicity, three or more TFDs can be manufactured by a similar method. In addition to the TFD, another semiconductor element such as a TFT may be formed over the substrate 101.

(Second Embodiment)
Hereinafter, a second embodiment according to the present invention will be described with reference to FIGS. This embodiment can be applied to a semiconductor device provided with a TFT and a TFD on the same glass substrate, for example, an active matrix type liquid crystal display device with a built-in optical sensor. Here, a method for simultaneously producing a display pixel TFT (pixel electrode driving TFT), a TFT constituting a driving CMOS circuit (driver circuit TFT), and an optical sensor TFD on a glass substrate. This will be specifically described. 2 to 4 are cross-sectional views illustrating manufacturing steps of the driver circuit n-channel TFT 228 and the p-channel TFT 229, the pixel electrode driving n-channel TFT 230, and the optical sensor TFD 231 described here. A) The manufacturing process proceeds sequentially in the order of FIG. 4 (J).

  First, as shown in FIG. 2A, a light-transmitting conductive film 202 is formed on a surface of a glass substrate 201 on which TFTs and TFDs are formed, and a TFD semiconductor layer is shielded from light on the conductive film 202. A light shielding layer 203 is formed.

  As the light transmissive conductive film 202, an ITO (indium tin oxide) film, an IZO (indium zinc oxide) film, or the like can be used. If the thickness of the conductive film 202 is 10 nm or more, the effect of the present invention can be obtained. However, if the thickness is too large, the transmittance is reduced, and thus the thickness is preferably 10 nm to 200 nm. More preferably, it is 20 nm to 150 nm. In this embodiment, an ITO film having a thickness of 100 nm is used.

  In a later TFD, the light shielding layer 203 for shielding light from the back surface direction of the substrate 201 can be formed using a metal film, a silicon film, or the like. In this embodiment, a molybdenum (Mo) film is formed by sputtering and patterned to form the light shielding layer 203 shown in FIG. In this case, the thickness of the light shielding layer 203 is preferably 30 nm to 300 nm, and more preferably 50 nm to 200 nm. In the present embodiment, the thickness of the light shielding layer 203 is set to 100 nm, for example.

  Next, as shown in FIG. 2B, base films 204 and 205 such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film are formed on the conductive film 202 and the light shielding layer 203 by, for example, a plasma CVD method. did. The base film is provided to prevent diffusion of impurities from the glass substrate. In the present embodiment, a silicon nitride film having a thickness of about 50 nm is formed as the lower first base film 204, and a silicon oxide film having a thickness of about 100 nm is formed thereon as the second base film 205. .

  Thereafter, an intrinsic (i-type) amorphous silicon film 206 having a thickness of about 20 to 80 nm, for example, 50 nm is formed on the second base film 205 by a plasma CVD method or the like.

Subsequently, a catalytic element is added to the surface of the amorphous silicon film 206. Specifically, an aqueous solution (nickel acetate aqueous solution) containing, for example, 5 ppm of a catalytic element (nickel in the present embodiment) in terms of weight is applied to the amorphous silicon film 206 by a spin coating method to contain the catalytic element. Layer 207 is formed. The usable catalytic element is one or more selected from iron (Fe), cobalt (Co), tin (Sn), lead (Pb), palladium (Pd), and copper (Cu) in addition to nickel (Ni). It is a seed element. Although the catalytic effect is smaller than these elements, ruthenium (Ru), rhodium (Rh), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), etc. also function as catalytic elements. At this time, the amount of the catalytic element to be doped is extremely small, and the concentration of the catalytic element on the surface of the amorphous silicon film 206 is managed by a total reflection X-ray fluorescence analysis (TRXRF) method. In this embodiment, it is about 5 × 10 ¹² atoms / cm ² . Prior to this step, the surface of the amorphous silicon film 206 may be slightly oxidized with ozone water or the like in order to improve the wettability of the surface of the amorphous silicon film 206 during spin coating.

  In this embodiment, a method of doping nickel by spin coating is used. However, a thin film made of a catalytic element (in this embodiment, nickel film) is deposited on the amorphous silicon film 206 by vapor deposition or sputtering. You may take the means to form.

  Thereafter, as shown in FIG. 2C, the amorphous silicon film 206 is crystallized by heat treatment in an inert atmosphere, for example, in a nitrogen atmosphere to obtain a crystalline silicon film 206a. This heat treatment is preferably performed at 550 to 620 ° C. for 30 minutes to 4 hours. In this embodiment, the heat processing for 1 hour were performed at 590 degreeC as an example. In this heat treatment, nickel added to the surface of the amorphous silicon film 106 diffuses into the amorphous silicon film 206 and silicidation occurs, and the crystallization of the amorphous silicon film 206 proceeds using this as a nucleus. . As a result, the amorphous silicon film 206 is crystallized to become a crystalline silicon film 206a. Note that although crystallization is performed here by heat treatment using a furnace, crystallization may be performed by an RTA (Rapid Thermal Annealing) apparatus using a lamp or the like as a heat source.

  Subsequently, as shown in FIG. 2D, the crystalline silicon film 206a obtained by the heat treatment is irradiated with a laser beam 208, whereby the crystalline silicon film 206a is further recrystallized to improve crystallinity. A crystalline silicon film 206b is formed. As the laser light at this time, an XeCl excimer laser (wavelength 308 nm) or a KrF excimer laser (wavelength 248 nm) can be applied. The beam size of the laser light at this time is shaped to be a long shape on the surface of the substrate 201, and the entire surface of the substrate is recrystallized by sequentially scanning in the direction perpendicular to the long direction. Do. At this time, scanning is performed so that parts of the beams overlap each other, so that laser irradiation is performed a plurality of times at any one point of the crystalline silicon film 206a, and uniformity can be improved. In this embodiment, the beam size is formed to be a long shape of 300 mm × 0.4 mm on the surface of the substrate 201, and scanning is sequentially performed at a step width of 0.02 mm in the direction perpendicular to the long direction. went. That is, a total of 20 laser irradiations are performed at any one point of the crystalline silicon film 206a.

As a laser that can be used in this step, a YAG laser, a YVO4 laser, or the like can be used in addition to the above-described pulse oscillation type or continuous emission type KrF excimer laser and XeCl excimer laser. Moreover, the irradiation energy density at this time is set to ²⁰⁰ to 450 mJ / cm ² , for example, 330 mJ / cm ² . The reason why the upper limit value of energy density (450 mJ / cm ² ) is lower than the upper limit value of energy density in the first embodiment is different from that of the first embodiment in this embodiment. This is because if the energy density of the laser beam is too high, the crystalline state of the crystalline silicon film 206a obtained in the previous step is reset.

  In this way, the crystalline silicon film 206a obtained by solid-phase crystallization is reduced in crystal defects by a melting and solidifying process by laser irradiation, and becomes a higher quality crystalline silicon film 206b. The crystal plane orientation of the crystalline silicon film 206b thus obtained is almost determined by the solid phase crystallization process using the catalytic element, and is mainly composed of the <111> crystal zone plane. ) Plane orientation and (211) plane orientation occupy 50% or more of the entire region. The domain diameter of the crystal domain (substantially the same plane orientation region) was 2 to 5 μm.

Thereafter, unnecessary regions of the crystalline silicon film 206b are removed, and element isolation is performed. As a result, as shown in FIG. 2E, the island-shaped semiconductor layer 209n, which later becomes the active region (source / drain region, channel region) of the n-channel TFT that will form the driver circuit portion, and the activity of the p-channel TFT An island-shaped semiconductor layer 209p to be a region (source / drain region, channel region) and an island-shaped semiconductor layer 209g to be an active region (source / drain region, channel region) of an n-channel TFT for driving a pixel electrode; Then, an island-shaped semiconductor layer 209d that will be an active region (n + / p ⁺ region, intrinsic region) of the photosensor TFD later is formed.

Here, p-type is applied to all of these semiconductor layers or a part of the semiconductor layers at a concentration of about 1 × 10 ^{16 to} 5 × 10 ¹⁷ / cm ³ for the purpose of controlling the threshold voltage. Boron (B) may be doped as an impurity element. Boron (B) may be added by an ion doping method, or may be doped at the same time when an amorphous silicon film is formed.

  Next, as shown in FIG. 3F, a gate insulating film 210 having a thickness of 20 to 150 nm is formed so as to cover the semiconductor layers 209n, 209p, 209g, and 209d to be the active regions, and then the semiconductor Gate electrodes 211n, 211p, and 211g are provided on the layers 209n, 209p, and 209g with a gate insulating film 210 interposed therebetween.

  In this embodiment, a silicon oxide film having a thickness of 100 nm is formed as the gate insulating film 210. The silicon oxide film was formed by using TEOS (Tetra Ethoxy Ortho Silicate) as a raw material and decomposing and depositing with oxygen at a substrate temperature of 150 to 600 ° C., preferably 300 to 450 ° C., by an RF plasma CVD method. Alternatively, the substrate temperature may be 350 to 600 ° C., preferably 400 to 550 ° C., by TEOS as a raw material and ozone gas and by low pressure CVD or normal pressure CVD. In addition, after the formation of the gate insulating film 210, in order to improve the bulk characteristics of the gate insulating film 210 and the interface characteristics of the crystalline silicon film / gate insulating film, it is performed at 500 to 600 ° C. for 1 to 4 hours in an inert gas atmosphere. Annealing may be performed. For the gate insulating film 210, an insulating film containing other silicon may be used as a single layer or a stacked structure.

  The gate electrodes 211n, 211p, and 211g are formed by depositing a refractory metal by sputtering and patterning it. Here, the gate electrode 211g of the subsequent pixel TFT is divided into two for the purpose of reducing the leakage current when the pixel TFT is turned off. This is a so-called dual gate structure in series. In addition, as the refractory metal at this time, an element selected from tantalum (Ta), tungsten (W), molybdenum (Mo) titanium (Ti), an alloy containing the element as a main component, or an alloy in which elements are combined A film (typically, a Mo—W alloy film or a Mo—Ta alloy film) can be used. As another alternative material, tungsten silicide, titanium silicide, or molybdenum silicide may be applied. In this embodiment, tungsten (W) is used, and the gate electrodes 211n, 211p, and 211g having a thickness of 300 to 600 nm, for example, 400 nm are formed. At this time, it is preferable to reduce the concentration of impurities contained in order to reduce the resistance, and by setting the oxygen concentration to 30 ppm or less, a specific resistance value of 20 μΩcm or less could be realized.

Next, a photoresist doping mask 212 is provided so as to cover the semiconductor layer 209d of the subsequent photosensor TFD so as to be slightly covered, and an active region of the TFT is formed by ion doping using the gate electrodes 211n, 211p, and 211g as a mask. Low-concentration impurities (phosphorus) 213 are implanted into the semiconductor layers 209n, 209p, and 209g. As the doping gas, phosphine (PH ₃ ) is used, the acceleration voltage is set to 60 to 90 kV, for example, 70 kV, and the dose amount is set to 1 × 10 ¹² to 1 × 10 ¹⁴ cm ⁻² , for example, 2 × 10 ¹³ cm ⁻² . By this step, in the island-shaped semiconductor layers 209n, 209p, and 209g, low concentration phosphorus 213 is implanted into the regions not covered with the gate electrodes 211n, 211p, and 211g, and the low concentration n-type impurity regions 214n and 214p, respectively. , 214 g. The impurity 213 is not implanted into the region masked by the gate electrodes 211n, 211p, 211g and the resist mask 212.

After removing the resist mask 212, as shown in FIG. 3G, a photoresist doping mask 215n is provided so as to cover the gate electrode 211n of the later n-channel TFT, and the subsequent p-channel TFT. In FIG. 3, a doping mask 215p made of a photoresist is provided so as to cover the gate electrode 211p further and to expose the outer edge portion of the semiconductor layer 209p. Also, a doping mask 215g made of a photoresist is provided for the subsequent pixel TFT so as to cover the gate electrode 211g so as to be slightly larger, and a part of the semiconductor layer 209d is exposed in the subsequent photosensor TFD. Is provided with a doping mask 215d made of photoresist. Thereafter, an impurity (phosphorus) 216 is implanted into each semiconductor layer at a high concentration by ion doping using the resist masks 215n, 215p, 215g, and 215d as masks. As the doping gas, phosphine (PH ₃ ) is used, the acceleration voltage is set to 60 to 90 kV, for example, 70 kV, and the dose amount is set to 1 × 10 ¹⁵ to 1 × 10 ¹⁶ cm ⁻² , for example, 5 × 10 ¹⁵ cm ⁻² .

  By this step, in the semiconductor layer 209n of the n-channel TFT, the impurity (phosphorus) 216 is implanted at a high concentration into the region exposed from the resist mask 215n, and the source / drain region 217n of the later n-channel TFT is formed. It is formed. In the semiconductor layer 209n, among regions that are covered with the resist mask 215n and are not doped with phosphorus 216 at a high concentration, a region where phosphorus is implanted at a low concentration in the previous step is an LDD (Lightly Doped Drain) region 218n. Thus, the region under the gate electrode 211n where phosphorus was not implanted in the previous step becomes a channel region 223n. The same applies to the pixel TFT. In the semiconductor layer 209g, an impurity (phosphorus) 216 is implanted at a high concentration in a region exposed from the resist mask 215g, and a source / drain region 217g of the subsequent pixel TFT (n-channel type) is formed. It is formed. Of the regions that are covered with the resist mask 215g and are not doped with the high concentration phosphorus 216, the region where the low concentration phosphorus is implanted in the previous step becomes the LDD region 218g, and the low concentration phosphorus is also implanted. A region under the non-existing gate electrode 211g becomes a channel region 223g. In the semiconductor layer 209p of the p-channel TFT, the impurity (phosphorus) 216 is implanted at a high concentration in the region exposed from the resist mask 215p to form the high-concentration n-type region 217p, and the phosphorus 216 is not implanted. Of the regions, the region below the gate electrode 211p is a channel region 223p. Also in the semiconductor layer 209d of the photosensor TFD, the impurity (phosphorus) 216 is implanted at a high concentration into the region exposed from the resist mask 215d, and high-concentration n-type regions 217d and 217d ′ are formed. Of these, the region 217d is an n-type region of TFD.

At this time, the concentration of the n-type impurity element (phosphorus) 216 in the film in the regions 217n, 217p, 217g, and 217d is 1 × 10 ¹⁹ to 1 × 10 ²¹ / cm ³ . Further, the n-type impurity element (phosphorus) 213 concentration in the n-channel TFT and the LDD regions 218n and 218g of the pixel TFT is 1 × 10 ¹⁷ to 1 × 10 ¹⁹ / cm ^3. When it is within the range, it functions as an LDD region. The LDD region is provided to alleviate electric field concentration at the junction between the channel region and the source / drain region, to reduce the leakage current during the TFT off operation, and to suppress deterioration due to hot carriers.

After removing the resist masks 215n, 215p, 215g, and 215d, as shown in FIG. 3H, the n-channel TFT semiconductor layer 209n and the pixel TFT semiconductor layer 209g are newly covered over the entire surface. In addition, photoresist doping masks 219n, 219g, and 219d are provided so as to cover part of the TFD semiconductor layer 209d. In this state, an impurity imparting p-type to the p-channel TFT semiconductor layer 209p and the TFD semiconductor layer 209d by ion doping, using the resist masks 219n, 219g, and 219d and the gate electrode 211p of the p-channel TFT as a mask. (Boron) 220 is injected. Diborane (B ₂ H ₆ ) is used as a doping gas, the acceleration voltage is 40 kV to 90 kV, for example, 75 kV, and the dose amount is 1 × 10 ¹⁵ to 1 × 10 ¹⁶ cm ⁻² , for example, 3 × 10 ¹⁵ cm ⁻² . To do.

  Through this process, boron 220 is implanted at a high concentration in the semiconductor layer 209p of the p-channel TFT in addition to the channel region 223p below the gate electrode 211p. By this step, the region 218p becomes p-type by inverting the n-type impurity phosphorus 213 implanted at a low concentration in the previous step, and becomes the source / drain region 221p of the later TFT. In addition, the region 217p is implanted with high-concentration boron 220 in addition to the high-concentration phosphorus 216 implanted in the previous step, and functions as a gettering region 222p. In addition, in the semiconductor layer 209d of the optical sensor TFD, boron 220 is implanted at a high concentration in a region exposed from the resist mask 219d, and a p-type region 221d of the later TFD is formed. In addition, the region 217d 'functions as the gettering region 222d by being implanted with high-concentration boron 220 in addition to the high-concentration phosphorus 216 implanted in the previous step. The region masked with the resist mask 219d and the resist mask 215d in the previous step and into which neither high-concentration phosphorus nor boron is implanted becomes an intrinsic region 223d of the later TFD.

At this time, the concentration in the film of the p-type impurity element (boron) 220 in the regions 221p, 221d, 222p, and 222d is 1.5 × 10 ^{19 to} 3 × 10 ²¹ / cm ³ . In the above process, since the active regions 209n and 209g of the n-channel TFT and the pixel TFT are entirely covered with the masks 219n and 219g, the boron 220 is not doped.

  Next, after removing the resist masks 219n, 219g, and 219d, the resist masks 219n, 219g, and 219d are subjected to heat treatment in an inert atmosphere, for example, a nitrogen atmosphere, so that getters for the channel regions 223n, 223g, LDD regions 218n, 218g, and intrinsic regions 223d are obtained. Do the ring.

In the present embodiment, the RTA process is used in which the substrate is moved to a high temperature atmosphere one by one and high temperature nitrogen gas is blown to raise and lower the temperature rapidly. As processing conditions, temperature raising / lowering was performed at a temperature raising / lowering rate exceeding 200 ° C./min, for example, heat treatment was performed at 650 ° C. for 10 minutes. As the heat treatment at this time, other methods can be used, and the conditions may be set by the practitioner for convenience. Of course, a general diffusion furnace (furnace furnace) or a lamp heating type RTA may be used. In this heat treatment step, as shown in FIG. 4I, in the semiconductor layer 209n and the pixel TFT 209g of the later n-channel TFT, phosphorus doped in the source / drain regions 217n and 217g The solid solubility of nickel is increased, and nickel existing in the channel regions 223n, 223g and LDD regions 218n, 218g is moved in the direction indicated by the arrow 224 from the channel region to the LDD region and then to the source / drain regions. . Further, also in the semiconductor layer 209p of the later p-channel TFT, phosphorus and boron doped in a high concentration in the gettering region 222p formed outside the source / drain regions, and lattice defects generated at the time of boron doping And the like move nickel existing in the channel region 223p and the source / drain region 221p from the channel region to the source / drain region and the gettering region in the direction indicated by the arrow 224 as well. Also in the semiconductor layer 209d of the later optical sensor TFD, phosphorus doped in the n-type region 217d and phosphorus and boron doped in the gettering region 222d formed outside the p-type region 221d are Similarly, nickel existing in the intrinsic region 223d and the p-type region 221d is moved in the direction indicated by the arrow 224. This heat treatment process moves nickel into the source / drain regions 217n and 217g of the n-channel TFT and the pixel TFT, the n-type region 217d of the TFD, and the gettering regions 222p and 222d of the p-channel TFT and the TFD. Therefore, the nickel concentration in these regions is 1 × 10 ¹⁸ / cm ³ or more.

  In this heat treatment step, n-type impurities (phosphorus) doped in the source / drain regions 217n and 217g and the LDD regions 218n and 218g of the n-channel TFT and the pixel TFT, and the n-type region 217d of the TFD, and p The activation of the p-type impurity (boron) doped in the source / drain region 221p of the channel TFT and the p-type region 221d of the TFD is simultaneously performed. As a result, the sheet resistance values of the n-channel TFT, the source / drain regions 217n and 217g of the pixel TFT, and the n-type region 217d of the TFD are about 0.5 to 1 kΩ / □, and the sheet resistance of the LDD regions 218n and 218g. The value was 30-60 kΩ / □. The sheet resistance values of the source / drain region 211p of the p-channel TFT and the p-type region 221p of the TFD were about 1 to 1.5 kΩ / □. In the gettering region, the doped n-type impurity element phosphorus and the p-type impurity element boron cancel the carriers (electrons and holes), and the sheet resistance value is several tens of kΩ / □, as the source / drain regions. However, in the p-channel TFT and TFD semiconductor layers 209p and 209d, the gettering region is arranged so as not to hinder the movement of carriers, which does not cause a problem in operation.

  Next, as shown in FIG. 4J, after an interlayer insulating film 226 is formed, TFT and TFD electrodes / wirings 227n, 227p, 227g, and 227d are formed.

As the interlayer insulating film 226, for example, a silicon nitride film, a silicon oxide film, or a silicon nitride oxide film is formed with a thickness of 400 to 1500 nm (typically 600 to 1000 nm). In this embodiment, a silicon nitride film 225 having a thickness of 200 nm and a silicon oxide film 226 having a thickness of 700 nm are continuously formed in this order to form a two-layer structure. Specifically, using a plasma CVD method, a silicon nitride film 225 was formed using SiH ₄ and NH ₃ as raw material gases, and then a silicon oxide film 226 was formed using TEOS and O ₂ as raw materials. The interlayer insulating film is not limited to this, and another insulating film containing silicon may have a single layer or a laminated structure, and an organic insulating film such as acrylic may be provided as an upper layer.

  Thereafter, a heat treatment is performed at 300 to 500 ° C. for about 30 minutes to 4 hours to perform a step of hydrogenating the semiconductor layer. In this step, hydrogen atoms are supplied to the active region / gate insulating film interface to terminate and inactivate dangling bonds that degrade TFT characteristics. In this embodiment, heat treatment was performed at 400 ° C. for 1 hour in a nitrogen atmosphere containing about 3% hydrogen. When the amount of hydrogen contained in the interlayer insulating films 225 and 226 (especially the silicon nitride film 225) is sufficient, the effect can be obtained even if heat treatment is performed in a nitrogen atmosphere. As another means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) may be performed.

  The electrodes and wirings 227n, 227p, 227g, and 227d of the TFT and TFD are formed using a two-layer film of a metal material, for example, titanium nitride and aluminum, after forming contact holes in the interlayer insulating films 225 and 226. . The titanium nitride film is provided as a barrier film for the purpose of preventing aluminum from diffusing into the semiconductor layer. Finally, annealing is performed at 350 ° C. for 1 hour.

  In this manner, an n-channel thin film transistor 228 and a p-channel thin film transistor 229 as driver circuit TFTs, a thin film transistor 230 for driving a pixel electrode, and a thin film diode 231 used as an optical sensor are completed. In the thin film transistor 230 for driving the pixel electrode, a transparent conductive film such as ITO is connected to one side of the electrode / wiring 227g to form a pixel electrode. Further, if necessary, contact holes are also provided on the gate electrodes 211n and 211p of the driver circuit TFT, and necessary electrodes are connected by the wiring 227. For the purpose of protecting the TFT, a protective film made of a silicon nitride film or the like may be provided on each TFT.

The field effect mobility of the TFT for driver circuit manufactured according to the above embodiment is as high as 250 to 300 cm ² / Vs for the n-channel thin film transistor 228 and 120 to 150 cm ² / Vs for the p-channel thin film transistor 229, and the threshold voltage is The n-type thin film transistor 228 has a very good characteristic of about 1 V, and the p-type thin film transistor 229 has a value of about −1.5 V. In addition, when a circuit such as an inverter chain or a ring oscillator is formed using a CMOS structure circuit in which the n-channel thin film transistor 228 and the p-channel thin film transistor 229 which are manufactured in this embodiment are complementarily formed, compared with a conventional circuit. High reliability and stable circuit characteristics. Further, the thin film transistor 230 for driving the pixel electrode also stably showed a very low value of 0.3 pA or less per unit W when the TFT was turned off, and showed excellent switching characteristics. Furthermore, the variation in the photocurrent characteristics of the thin film diode 231 can be reduced to 1/3 or less of the conventional method, and stable optical sensing characteristics can be obtained.

  According to this embodiment, an active matrix substrate with a built-in driver with an optical sensor function can be realized. This active matrix substrate is suitably used for a liquid crystal display device having a structure having a transmission region. When used in such a display device, it is possible to prevent the light shielding layer from being in a potential floating state without reducing the aperture ratio, so that variations in TFD photocurrent characteristics can be reduced.

  Further, according to the present embodiment, since the pixel electrode driving TFT, the driver circuit TFT, and the optical sensor TFD can be simultaneously formed on the same substrate, a great cost merit such as reduction in the number of components can be obtained. Furthermore, in this embodiment, it was confirmed that the ESD defect generated in the manufacturing process is zero, and the conductive film formed on the entire substrate surface has an effect of significantly suppressing ESD. Therefore, not only the yield of good products could be improved, but also the quality and reliability of the product could be improved.

  As described above, according to the present embodiment, when manufacturing two types of semiconductor elements, TFT and TFD, the manufacturing process is not complicated, and the manufacturing process is low cost and high yield. In this way, a semiconductor device including a semiconductor element having optimum characteristics can be realized.

(Third embodiment)
A third embodiment using the present invention will be described. Here, the pixel structure is different from that of the second embodiment in a layer structure, a pixel electrode driving TFT for display on a glass substrate, a TFT (driver circuit TFT) constituting a driver circuit CMOS, and an optical sensor. A method for simultaneously manufacturing TFD will be described. FIG. 5 is a cross-sectional view showing a manufacturing process of a TFT and a TFD described in this embodiment, and the processes sequentially proceed in the order of FIGS. 5A to 5E.

  First, in FIG. 5A, a light-blocking layer 302 is formed on the surface of the glass substrate 301 where TFTs and TFDs are to be formed to block light from the substrate back surface direction in the subsequent TFD. In the present embodiment, for example, a 100 nm Mo film was used. Subsequently, a light-transmitting conductive film 303 is formed over the glass substrate 301 and the light-blocking layer 302. As the light-transmitting conductive film 303, an ITO (indium tin oxide) film, an IZO (indium zinc oxide) film, or the like can be used. If the thickness of the conductive film 303 is 10 nm or more, the effect of the present invention can be obtained. However, if the thickness is too large, the transmittance decreases, and therefore, the thickness is preferably 10 nm to 200 nm, and more preferably 20 nm to 150 nm. . In this embodiment, an IZO film having a thickness of 100 nm is used.

  Next, as shown in FIG. 5B, a silicon nitride film is formed on the IZO film 303 as a lower first base film 304 by a method similar to the second embodiment, and the second base film is formed thereon. A silicon oxide film was formed as the underlying film 305. Next, an intrinsic (i-type) amorphous silicon film 306 having a thickness of 50 nm was formed by a plasma CVD method or the like. Subsequently, a catalyst element is added to the surface of the amorphous silicon film 306 by a method similar to that of the second embodiment to form the catalyst element-containing layer 307. Nickel can be used as the catalyst element.

  Thereafter, as shown in FIG. 5C, heat treatment is performed in an inert atmosphere, for example, in a nitrogen atmosphere, and the amorphous silicon film 306 is formed using nickel added to the surface of the amorphous silicon film 306 as a nucleus. Is crystallized to obtain a crystalline silicon film 306a.

  Next, as shown in FIG. 5D, the crystalline silicon film 306a is further recrystallized by irradiating the crystalline silicon film 306a with a laser beam 308 in the same manner as in the second embodiment. Thus, a crystalline silicon film 306b with improved crystallinity is formed.

Thereafter, unnecessary regions of the crystalline silicon film 306b are removed, and element isolation is performed. In this manner, as shown in FIG. 5E, an island-shaped semiconductor layer 309n that will become an active region (source / drain region, channel region) of an n-channel TFT that will later constitute a driver circuit portion, and a p-channel TFT Island-like semiconductor layer 309p that becomes an active region (source / drain region, channel region) of the semiconductor device and an island-like semiconductor layer that becomes an active region (source / drain region, channel region) of an n-channel TFT for driving a pixel electrode 309 g and an island-shaped semiconductor layer 309 d that will later become an active region (n ⁺ / p ⁺ region, intrinsic region) of the photosensor TFD are formed.

  In the following, although not shown, the TFTs and the TFDs are completed by using the island-like semiconductor layers 309n, 309p, 309g, and 309d as the active regions of the TFTs and the TFDs by a method similar to the second embodiment. In the present embodiment, similarly to the second embodiment, an n-channel TFT and a p-channel TFT for a driver circuit having a high current driving capability can be obtained, and a leakage current at the time of TFT off operation is small. A pixel electrode driving TFT having good switching characteristics was obtained. Furthermore, the variation in TFD photocurrent characteristics could be reduced to 1/3 or less of the conventional one, and stable optical sensing characteristics were obtained. Also in the manufacturing process of the present embodiment, the number of ESD defects generated in the manufacturing process is zero, which has a great effect on ESD suppression.

  As in the second embodiment, this embodiment can be applied to an active matrix substrate with a built-in driver with a photosensor function that can be used in a liquid crystal display device having a structure having a transmission region.

(Fourth embodiment)
Hereinafter, a fourth embodiment of a semiconductor device according to the present invention will be described with reference to the drawings. This embodiment is different from the above-described embodiment in that a light shielding layer is provided on the back side of the TFT. Here, an active matrix substrate provided with a plurality of pixel electrode driving TFTs will be described as an example. However, a driver circuit TFT and an optical sensor TFD may be provided in addition to the pixel electrode driving TFT. The present embodiment can be suitably used for a display device such as a projector in which the intensity of light incident from the back side of the TFT is extremely large.

  FIG. 6 is a schematic cross-sectional view showing the semiconductor device of this embodiment. For simplicity, the same components as those in FIGS. 2 to 4 are denoted by the same reference numerals, and description thereof is omitted.

  The semiconductor device of this embodiment includes an insulating substrate 201, a light transmissive conductive film 202 formed on the surface of the substrate 201, and a plurality of thin film transistors 350 provided on the substrate 201. Each thin film transistor 350 includes a semiconductor layer 209 n serving as an active region, and an island-shaped light shielding layer 203 disposed between the semiconductor layer 209 n and the substrate 201. Each light shielding layer 203 is electrically connected by a conductive film 202. The light shielding layer 203 is disposed so as to shield at least a part of the semiconductor layer 209 n when viewed from the back surface side of the substrate 201 for the purpose of blocking light incident on the semiconductor layer 209 n from the back surface side of the substrate 201. In FIG. 6, the light shielding layer 203 is disposed so as to shield the entire corresponding semiconductor layer 209n, but it is sufficient that the light shielding layer 203 is disposed so as to shield at least the channel region 223n of the semiconductor layer 209n. The channel region 223n and the LDD region 218n are arranged to be shielded from light.

  In the illustrated example, the configuration of each thin film transistor 350 is the same as that of the n-channel thin film transistor 228 described above with reference to FIG. The structure of the thin film transistor is not limited to the structure illustrated. For example, a double gate structure such as a thin film transistor 230 in FIG.

  In the present embodiment, the conductive film 202 and the light shielding layer 203 are formed using the same material by the same method as described above with reference to FIG. In this embodiment, the light shielding layer 203 is disposed in a region of the substrate 201 where TFTs are to be formed. Thereafter, a semiconductor layer 209n serving as an active region of the TFT is provided on the light shielding layer 203 by a method similar to the method described above with reference to FIGS. 2B to 4J, and then gate insulation is performed. Formation of the film 210n and the gate electrode 211n, ion implantation into the semiconductor layer 209n, and formation of the electrode 227n are performed, whereby the thin film transistor 350 is obtained.

  When this embodiment is applied to a display device such as a projector, the light shielding layer 203 is electrically connected to the island-shaped light shielding layer 203 by a light-transmitting conductive film 202 without reducing the aperture ratio. Therefore, the variation in characteristics of the thin film transistor 350 can be reduced. Further, since the conductive film 202 also serves as an electric field shield against ESD, ESD in the manufacturing process can be suppressed.

(Fifth embodiment)
In the present embodiment, a display device having a sensor function will be described. These display devices are configured using a substrate on which TFTs and TFDs are formed using any of the embodiments described above.

  The display device having the sensor function of the present embodiment is, for example, a liquid crystal display device with a touch sensor, and has a display region and a frame region located around the display region. The display area has a plurality of display units (pixels) and a plurality of photosensor units. Each display unit includes a pixel electrode and a pixel switching TFT, and each photosensor unit includes a TFD. A display drive circuit for driving each display unit is provided in the frame region, and a drive circuit TFT is used as the drive circuit. The pixel switching TFT, the driving circuit TFT, and the TFD of the optical sensor unit are formed on the same substrate. Note that in the display device of the present invention, at least two of the TFDs in the photosensor portion may have a light shielding layer, and the TFT may or may not have a light shielding layer.

  In the present embodiment, the optical sensor unit is disposed adjacent to a corresponding display unit (for example, primary color pixels). One photosensor unit may be arranged for one display unit, or a plurality of photosensor units may be arranged. Or you may arrange | position one photosensor part at a time with respect to the set of a some display part. For example, one optical sensor unit can be provided for a color display pixel composed of three primary color (RGB) pixels. As described above, the number (density) of the optical sensor units with respect to the number of display units can be appropriately selected according to the resolution.

  If a color filter is provided on the observer side of the optical sensor unit, the sensitivity of the TFD constituting the optical sensor unit may be reduced. Therefore, no color filter is provided on the observer side of the optical sensor unit. It is preferable.

  Note that the configuration of the display device of the present embodiment is not limited to the above. For example, a display device to which an ambient sensor that controls the display brightness in accordance with the illuminance of external light can be configured by arranging a TFD for an optical sensor in the frame region. In addition, by arranging a color filter on the observer side of the optical sensor unit and receiving light through the color filter by the optical sensor unit, the optical sensor unit can also function as a color image sensor.

  Hereinafter, the configuration of the display device of this embodiment will be described with reference to the drawings, taking a touch panel liquid crystal display device including a touch panel sensor as an example.

  FIG. 7 is a circuit diagram showing an example of the configuration of the optical sensor unit arranged in the display area. The photosensor section includes a photosensor thin film diode 401, a signal storage capacitor 402, and a thin film transistor 403 for extracting a signal stored in the capacitor 402. After the RST signal is input and the RST potential is written into the node 404, when the potential of the node 404 is decreased due to light leakage, the gate potential of the thin film transistor 403 is changed to open and close the TFT gate. Thereby, the signal VDD can be taken out.

  FIG. 8 is a schematic cross-sectional view showing an example of an active matrix type touch panel liquid crystal display device. In this example, one photosensor unit is arranged for each pixel.

  The liquid crystal display device shown in the figure includes a liquid crystal module 502 and a backlight 501 disposed on the back side of the liquid crystal module 502. Although not shown here, the liquid crystal module 502 includes, for example, a light-transmitting rear substrate, a front substrate disposed so as to face the rear substrate, and a liquid crystal layer provided between these substrates. Composed. The liquid crystal module 502 includes a plurality of display portions (primary color pixels), and each display portion includes a pixel electrode (not shown) and a pixel switching thin film transistor 505 connected to the pixel electrode. Yes. An optical sensor unit including a thin film diode 506 is disposed adjacent to each display unit. Although not shown, a color filter is disposed on the viewer side of each display unit, but no color filter is provided on the viewer side of the optical sensor unit. A light blocking layer 507 is disposed between the thin film diode 506 and the backlight 501, and light from the backlight 501 is blocked by the light blocking layer 507 and does not enter the thin film diode 506, but only the external light 504 is thin film diode 506. Is incident on. The incident of the external light 504 is sensed by the thin film diode 506, and a light sensing touch panel is realized.

  Note that the light shielding layer 507 may be arranged so that at least light from the backlight 501 does not enter the intrinsic region of the thin film diode 506.

  FIG. 9 is a schematic plan view showing an example of a rear substrate in an active matrix type touch panel liquid crystal display device. The liquid crystal display device of the present embodiment is composed of a large number of pixels (R, G, B pixels), but only two pixels are shown here for the sake of simplicity.

  Each of the rear substrates 1000 is disposed adjacent to each of the plurality of display portions (pixels) each including the pixel electrode 22 and the pixel switching thin film transistor 24, and includes a photosensor photodiode 26 and a signal storage capacitor 28. And an optical sensor unit including an optical sensor follower thin film transistor 29.

  The thin film transistor 24 has, for example, the same configuration as the pixel electrode driving thin film TFT described in the second embodiment, that is, a dual gate LDD structure having two gate electrodes and an LDD region. The source region of the thin film transistor 24 is connected to the pixel source bus line 34, and the drain region is connected to the pixel electrode 22. The thin film transistor 24 is turned on / off by a signal from the pixel gate bus line 32. Thus, display is performed by applying a voltage to the liquid crystal layer by the pixel electrode 22 and the counter electrode formed on the front substrate disposed to face the back substrate 1000 and changing the alignment state of the liquid crystal layer.

On the other hand, the photosensor photodiode 26 has the same configuration as the TFD described in the second embodiment, for example, and is an intrinsic region located between the p ⁺ region 26p, the n ⁺ region 26n, and the regions 26p and 26n. 26i. The signal storage capacitor 28 has a gate electrode layer and a Si layer as electrodes, and a capacitance is formed by a gate insulating film. The p ⁺ region 26p in the photosensor photodiode 26 is connected to the photosensor RST signal line 36, and the n ⁺ region 26n is connected to the lower electrode (Si layer) of the signal storage capacitor 28. Then, it is connected to the optical sensor RWS signal line 38. Further, the n ⁺ region 26 n is connected to the gate electrode layer in the photosensor follower thin film transistor 29. The source and drain regions of the photosensor follower thin film transistor 29 are connected to the photosensor VDD signal line 40 and the photosensor COL signal line 42, respectively.

  As described above, the photosensor photodiode 26, the signal storage capacitor 28, and the photosensor follower thin film transistor 29 correspond to the thin film diode 401, the capacitor 402, and the thin film transistor 403 of the drive circuit shown in FIG. It constitutes the drive circuit for the optical sensor. The operation at the time of optical sensing by this drive circuit will be described below.

(1) First, the RWS signal is written into the signal storage capacitor 28 by the RWS signal line 38. As a result, a positive electric field is generated on the n ⁺ region 26 n side of the photosensor photodiode 26, and the photosensor photodiode 26 is in a reverse bias state. (2) In the photosensor photodiode 26 present in the region of the substrate surface where light is irradiated, light leaks and the charge is released to the RST signal line 36 side. (3) As a result, the potential on the n ⁺ region 26n side is lowered, and the gate voltage applied to the photosensor follower thin film transistor 29 is changed by the potential change. (4) The VDD signal is applied from the VDD signal line 40 to the source side of the photosensor follower thin film transistor 29. When the gate voltage fluctuates as described above, the value of the current flowing to the COL signal line 42 connected to the drain side changes, so that the electrical signal can be extracted from the COL signal line 42. (5) The RST signal is written from the COL signal line 42 to the photosensor photodiode 26, and the potential of the signal storage capacitor 28 is reset. Optical sensing is possible by repeating the operations (1) to (5) while scanning.

  The configuration of the back substrate in the touch panel liquid crystal display device of the present embodiment is not limited to the configuration shown in FIG. For example, an auxiliary capacitor (Cs) may be provided in each pixel switching TFT. In the example shown in the figure, a photosensor unit is provided adjacent to each of the RGB pixels. However, as described above, one photosensor is provided for three pixel sets (color display pixels) composed of RGB pixels. The part may be arranged.

  Here, FIG. 8 will be referred to again. In the example described above, as can be seen from the cross-sectional view shown in FIG. 8, the thin film diode 506 is disposed in the display region and used as a touch sensor. However, the thin film diode 506 is formed outside the display region and back It can also be used as an ambient sensor for controlling the brightness of the light 501 in accordance with the illuminance of the external light 504.

  FIG. 10 is a perspective view illustrating a liquid crystal display device with an ambient light sensor. The liquid crystal display device 2000 includes an LCD substrate 50 having a display area 52, a gate driver 56, a source driver 58 and an optical sensor unit 54, and a backlight 60 disposed on the back side of the LCD substrate 50. An area of the LCD substrate 50 that is located around the display area 52 and in which the drivers 56 and 58 and the optical sensor unit 54 are provided may be referred to as a “frame area”.

  The luminance of the backlight 60 is controlled by a backlight control circuit (not shown). Although not shown, TFTs are used for the display area 52 and the drivers 56 and 58, and TFDs are used for the optical sensor unit 54. The optical sensor unit 54 generates an illuminance signal based on the illuminance of external light, and inputs the illuminance signal to the backlight control circuit using a connection using a flexible substrate. The backlight control circuit generates a backlight control signal based on the illuminance signal and outputs it to the backlight 60.

  When the present invention is applied, an organic EL display device with an ambient light sensor can also be configured. Such an organic EL display device can have a configuration in which a display unit and a photosensor unit are arranged on the same substrate, like the liquid crystal display device shown in FIG. There is no need to provide the light 60. In this case, the optical sensor unit 54 is connected to the source driver 58 by wiring provided on the substrate 50, and an illuminance signal from the optical sensor unit 54 is input to the source driver 58. The source driver 58 changes the luminance of the display unit 52 based on the illuminance signal.

  Although specific embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible. Using the TFT of the present invention, a circuit for performing analog driving and a circuit for performing digital driving can be simultaneously formed on a glass substrate. For example, in the case of a circuit that performs analog driving, a source side driving circuit, a pixel portion, and a gate side driving circuit are included. The source side driving circuit includes a shift register, a buffer, a sampling circuit (transfer gate), and a gate side driving circuit. Are provided with a shift register, a level shifter, and a buffer. Further, if necessary, a level shifter circuit may be provided between the sampling circuit and the shift register. Further, according to the manufacturing process of the present invention, a memory and a microprocessor can be formed.

  Furthermore, the present invention can be applied not only to a transmissive liquid crystal display device having a photosensor function but also to a transflective liquid crystal display device including a reflective portion. That is, the present invention can be implemented in all electronic devices in which these liquid crystal display devices are incorporated in a display unit. As described above, the application range of the present invention is extremely wide and can be applied to electronic devices in various fields.

  According to the present invention, it is possible to realize a semiconductor device including a plurality of semiconductor elements having stable element characteristics. In particular, when applied to a semiconductor device having a plurality of TFDs used as an optical sensor, variation in leakage current (photocurrent) at the time of reverse bias with respect to TFD light can be greatly reduced, and stable optical sensing characteristics are obtained. An optical sensor TFD can be realized. In addition, by combining such a photosensor TFD with a screen portion of a transmissive or transflective liquid crystal display device, it is possible to suppress a decrease in aperture ratio and a stable characteristic while suppressing a decrease in display luminance. A liquid crystal display device including the optical sensor can be realized. When a TFD for an optical sensor is simultaneously formed on an active matrix substrate used for such a transmissive or transflective liquid crystal display device in addition to a pixel switching TFT and a peripheral drive circuit TFT, the TFT and the TFD are formed. Can be simultaneously formed on the same substrate, so that there is a large cost advantage such as a reduction in the number of parts. Furthermore, in manufacturing these two types of semiconductor elements, the ESD in the manufacturing process is suppressed, and the manufacturing process is not complicated, and the manufacturing process is low-cost and high yield. A semiconductor device including a TFT and a TFD having optimum characteristics can be manufactured. As a result, the target product can be made compact, high performance, low cost, high quality, and high reliability.

  The present invention can be widely applied to semiconductor devices provided with a plurality of semiconductor elements. In particular, when applied to a semiconductor device such as an image sensor or an optical sensor having a plurality of thin film diodes as a semiconductor element, it is advantageous because the sensing characteristics of the thin film diode can be stabilized. Further, the present invention can be applied to a display device such as a projector including a plurality of thin film transistors. Furthermore, the present invention can be suitably used for an active matrix substrate including a thin film diode and a thin film transistor, a transmissive or transflective liquid crystal display device using the active matrix substrate, and an electronic device including such a display device.

FIGS. 3A to 3H are schematic process cross-sectional views for explaining a method for manufacturing a semiconductor device according to a first embodiment of the present invention. FIGS. FIGS. 4A to 4E are schematic process cross-sectional views for explaining a method for manufacturing a semiconductor device according to a second embodiment of the present invention. (F) to (H) are schematic process cross-sectional views for explaining a method for manufacturing a semiconductor device according to a second embodiment of the present invention. (I) And (J) is typical process sectional drawing for demonstrating the manufacturing method of the semiconductor device by the 2nd Embodiment by this invention. FIGS. 9A to 9E are schematic process cross-sectional views for explaining a method for manufacturing a semiconductor device according to a third embodiment of the present invention. FIGS. It is typical sectional drawing which shows the semiconductor device of 4th Embodiment by this invention. It is a circuit diagram of optical sensor TFD. It is a block diagram of an optical sensor type touch panel. FIG. 10 is a schematic plan view illustrating a back substrate in a touch panel liquid crystal display device according to a fifth embodiment of the invention. It is a perspective view which illustrates the liquid crystal display device with an ambient light sensor of 5th Embodiment by this invention. (A) And (B) is a figure which shows the photocurrent characteristic of the conventional TFD, (A) is a measurement result which shows the TFD application voltage dependence of a leakage current value, (B) is (A) It is a graph which shows the TFD application voltage dependence of the variation of the leakage current value calculated | required from the measurement result of this. (A) And (B) is a figure which shows the photocurrent characteristic of TFD of embodiment by this invention, (A) is a measurement result which shows the TFD application voltage dependence of a leakage current value, (B) is It is a graph which shows the TFD application voltage dependence of the variation in the leakage current value calculated | required from the measurement result of (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Substrate 102 Light-transmitting conductive film 103 Light-shielding layer 104, 105 Base film 106 Amorphous silicon film 106a, 106b Crystalline silicon region 107 Laser light 108d Insular semiconductor layer 109 Insulating film 111, 116 Mask 112 N-type impurity 114 n ⁺ region 117 p-type impurity 118 p ⁺ region 119 intrinsic region 120 silicon nitride film 121 silicon oxide film 123 electrode / wiring 125 thin film diode

Claims (37)

A substrate having optical transparency;
A plurality of semiconductor elements supported by the substrate;
A plurality of island-shaped light shielding layers having conductivity disposed between the substrate and the plurality of semiconductor elements;
A light-transmitting conductive film disposed between the substrate and the plurality of semiconductor elements,
The plurality of island-shaped light shielding layers are associated with at least two semiconductor elements of the plurality of semiconductor elements, and are electrically connected to the conductive film.   The semiconductor element according to claim 1, wherein the at least two semiconductor elements include a plurality of thin film diodes, and each thin film diode includes a semiconductor layer including an n-type region and a p-type region.   The semiconductor device according to claim 2, wherein the semiconductor layer of each thin film diode further includes an intrinsic region formed between the n-type region and the p-type region.   4. The semiconductor device according to claim 3, wherein when viewed from the substrate side, each island-shaped light shielding layer is arranged so as to shield at least an intrinsic region of the semiconductor layer of the associated thin film diode. The plurality of semiconductor elements include a plurality of thin film transistors,
Each thin film transistor has a semiconductor layer including a channel region, a source region, and a drain region,
5. The semiconductor device according to claim 2, wherein a light shielding layer is not provided between the semiconductor layer of each thin film transistor and the substrate. The at least two semiconductor elements further include a plurality of thin film transistors;
Each of the plurality of thin film transistors has a semiconductor layer including a channel region, a source region, and a drain region,
5. The semiconductor device according to claim 2, wherein a part of the plurality of island-shaped light shielding layers is disposed between a semiconductor layer of the plurality of thin film transistors and the substrate.   7. The semiconductor device according to claim 5, wherein the semiconductor layers of the plurality of thin film transistors and the semiconductor layers of the plurality of thin film diodes are crystalline semiconductor layers.   The semiconductor device according to claim 5, wherein the plurality of thin film transistors include an n-channel thin film transistor and a p-channel thin film transistor. The at least two semiconductor elements include a plurality of thin film transistors;
Each thin film transistor includes a semiconductor layer including a channel region, a source region, and a drain region, a gate insulating film provided on the semiconductor layer, and a gate electrode that controls conductivity of the channel region.
2. The semiconductor device according to claim 1, wherein each island-shaped light shielding layer is disposed so as to shield at least a channel region of a semiconductor layer of an associated thin film transistor when viewed from the substrate side. Each of the plurality of semiconductor elements has an island-shaped semiconductor layer,
10. The semiconductor device according to claim 1, wherein each island-shaped light shielding layer is disposed so as to shield at least a part of a semiconductor layer of an associated semiconductor element when viewed from the substrate side. .   The semiconductor device according to claim 10, wherein each island-shaped light shielding layer is disposed so as to shield the semiconductor layer of the associated semiconductor element when viewed from the substrate side.   The semiconductor device according to claim 1, wherein the plurality of island-shaped light shielding layers have the same potential.   The semiconductor device according to claim 1, wherein the conductive film is formed over the entire surface of the substrate.   The semiconductor device according to claim 1, wherein the plurality of island-shaped light shielding layers are disposed on the conductive film so as to be in contact with the conductive film.   The semiconductor device according to claim 1, wherein the conductive film is disposed on the plurality of island-shaped light shielding layers so as to be in contact with the plurality of island-shaped light shielding layers. (A) forming a light transmissive conductive film on a light transmissive substrate;
(B) providing a plurality of conductive island-shaped light shielding layers on the conductive film;
(C) forming an optically transparent insulating film on the conductive film and the plurality of island-shaped light shielding layers;
(D) forming a semiconductor film on the insulating film;
(E) A step of patterning the semiconductor film to form a plurality of island-shaped semiconductor layers to be active regions of a semiconductor element, wherein at least two of the plurality of island-shaped semiconductor layers are formed into the plurality of island-shaped semiconductor layers. Forming on the light shielding layer of the semiconductor device. (A) providing a plurality of island-shaped light shielding layers having conductivity on a substrate having optical transparency;
(B) forming a light transmissive conductive film so as to cover the substrate and the plurality of light shielding layers;
(C) forming a light-transmitting insulating film on the conductive film;
(D) forming a semiconductor film on the insulating film;
(E) a step of patterning the semiconductor film to form a plurality of island-like semiconductor layers to be active regions of a semiconductor element, wherein at least two of the plurality of island-like semiconductor layers are formed into the plurality of island-like semiconductor layers. A method of manufacturing a semiconductor device including a step of forming on a light shielding layer.   18. The method of manufacturing a semiconductor device according to claim 16, wherein the plurality of island-shaped semiconductor layers include a plurality of island-shaped semiconductor layers serving as an active region of a thin film diode.   The method for manufacturing a semiconductor device according to claim 16, wherein the plurality of island-shaped semiconductor layers include a plurality of island-shaped semiconductor layers serving as active regions of thin film transistors. The plurality of island-shaped semiconductor layers include a plurality of island-shaped semiconductor layers that become active regions of thin film diodes, and a plurality of island-shaped semiconductor layers that become active regions of thin film transistors,
The step (e)
Forming a plurality of island-shaped semiconductor layers to be active regions of the thin-film diode on the plurality of island-shaped light shielding layers;
And forming a plurality of island-shaped semiconductor layers to be active regions of the thin film transistors on a region of the surface of the substrate where the plurality of island-shaped light shielding layers are not formed. Semiconductor device manufacturing method. After step (e)
A step (f1) of doping an n-type impurity element into a region to be a later n-type region of each island-shaped semiconductor layer to be an active region of the thin-film diode;
19. The method of manufacturing a semiconductor device according to claim 18, further comprising a step (f2) of doping a p-type impurity element into a region to be a subsequent p-type region among the island-shaped semiconductor layers to be an active region of the thin-film diode. Method.   In the steps (f1) and (f2), an n-type impurity element is doped between a region doped with an n-type impurity element and a region doped with a p-type impurity element. The method of manufacturing a semiconductor device according to claim 21, wherein the method is performed so that a region to which both of the p-type impurity element and the p-type impurity element are not doped remains.   The n-type impurity element and the p-type impurity element formed between the region doped with the n-type impurity element and the region doped with the p-type impurity element in each island-like semiconductor layer serving as an active region of the thin-film diode. 23. The method of manufacturing a semiconductor device according to claim 22, wherein the region where both are not doped is arranged so as to be shielded from light by a corresponding island-shaped light shielding layer when viewed from the substrate side. The plurality of island-shaped semiconductor layers further includes a plurality of island-shaped semiconductor layers to be active regions of the thin film transistor,
After step (e)
(G1) forming a gate insulating film on the semiconductor layer serving as an active region of the thin film transistor;
(G2) forming a gate electrode on the gate insulating film;
(G3) further comprising a step of doping an n-type impurity element into a region to be a source region and a drain region later in the semiconductor layer of the thin film transistor,
24. The method of manufacturing a semiconductor device according to claim 21, wherein the step (g3) is performed simultaneously with the step (f1). After the step (e),
(G1) forming a gate insulating film on the semiconductor layer serving as an active region of the thin film transistor;
(G2) forming a gate electrode on the gate insulating film;
(G4) further comprising a step of doping a p-type impurity element into a region to be a source region and a drain region later in the semiconductor layer to be an active region of the thin film transistor,
24. The method of manufacturing a semiconductor device according to claim 21, wherein the step (g4) is performed simultaneously with the step (f2). The plurality of island-shaped semiconductor layers further includes a semiconductor layer that becomes an active region of an n-type thin film transistor and a semiconductor layer that becomes an active region of a p-type thin film transistor,
After the step (e),
(G1) forming a gate insulating film on a semiconductor layer serving as an active region of the n-type thin film transistor and the p-type thin film transistor;
(G2) forming a gate electrode on the gate insulating film;
(G5) a step of doping an n-type impurity element into a region that will later become a source region and a drain region of the semiconductor layer that becomes an active region of the n-type thin film transistor;
(G6) doping a p-type impurity element into a region that later becomes a source region and a drain region of the semiconductor layer that becomes an active region of the p-type thin film transistor,
24. The method of manufacturing a semiconductor device according to claim 21, wherein the step (g5) is performed simultaneously with the step (f1), and the step (g6) is performed simultaneously with the step (f2).   27. A semiconductor device manufactured by the manufacturing method according to claim 16.   An electronic apparatus comprising the semiconductor device according to claim 1.   An electronic apparatus comprising an optical sensor unit having the semiconductor device according to claim 1.   An electronic apparatus comprising both the display unit and the optical sensor unit, comprising the semiconductor device according to claim 1.   The electronic device according to claim 30, wherein the plurality of semiconductor elements include a thin film transistor and a thin film diode, the display unit includes the thin film transistor, and the optical sensor unit includes the thin film diode.   32. The electronic apparatus according to claim 30, wherein the optical sensor unit is an ambient sensor for adjusting luminance of the display unit.   The electronic device according to claim 30 or 31, wherein the optical sensor unit is a touch panel sensor of the display unit. A display area having a plurality of display portions;
A display device including a frame region located around the display region,
It further includes an optical sensor unit including a plurality of thin film diodes,
Each display unit includes an electrode and a thin film transistor connected to the electrode,
The thin film transistor and the plurality of thin film diodes are formed on the same substrate having translucency,
Each of the plurality of thin film diodes includes a semiconductor layer including an n-type region, a p-type region, and an intrinsic region provided between the n-type region and the p-type region,
A plurality of conductive light-shielding layers disposed between the plurality of thin-film diodes and the substrate;
A light-transmitting conductive film disposed between the plurality of thin film diodes and the substrate;
The plurality of light shielding layers are disposed so as to shield at least the intrinsic region among the semiconductor layers of the plurality of thin film diodes when viewed from the substrate side, and are electrically connected to the conductive film. Display device.   The display device according to claim 34, further comprising a backlight.   36. The apparatus according to claim 35, comprising a plurality of the optical sensor units, wherein each of the plurality of optical sensor units is arranged in the display area corresponding to each display unit or a set of two or more display units. Display device. The backlight has a backlight control circuit that adjusts the luminance of light emitted from the backlight,
The display device according to claim 35, wherein the light sensor unit is arranged in the frame region, generates an illuminance signal based on an illuminance of external light, and outputs the illuminance signal to the backlight control circuit.

Images