JP2006140336A - Fabrication process of thin film semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fabrication technology of a tin film semiconductor device in which a semiconductor film can be made thin while suppressing fabrication cost increase. <P>SOLUTION: A semiconductor material is applied to a substrate 10 by liquid drop ejection method and dried while defining the drying conditions such that the concentration of solid content of the semiconductor material reaches a saturation level substantially simultaneously over the entire liquid drop thus forming a substantially circular semiconductor film 11 (refer to fig. 3(a)). Subsequently, a gate insulating film 12 is formed to cover the entire surface of the semiconductor film 11 (refer to fig. 3(b)) and then a substantially rectangular gate electrode 13 is formed on the gate insulating film 12 (refer to fig. 3(c)). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a thin film semiconductor device.

A thin film transistor (TFT) is composed of a thin film such as a conductive film, an insulating film, and a semiconductor film, and a CVD (Chemical Vapor Deposition) method or a sputtering method is generally used to form such a thin film.
By the way, in order to improve the electrical characteristics of the TFT, it is necessary to form a thin semiconductor film. In order to realize such a thin semiconductor film, a CVD method or the like has been conventionally used (see, for example, Patent Document 1 below).

JP 7-153970 A

  However, an apparatus for forming a thin film using the CVD method is very expensive and has a problem of low throughput. Furthermore, in order to form a thin film by using the CVD method, it is necessary to form a mask pattern or the like using a resist material, and there is a problem that the manufacturing cost increases.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a manufacturing technique of a thin film semiconductor device capable of reducing the thickness of a semiconductor film or the like while suppressing manufacturing costs.

  In order to achieve the above object, a method of manufacturing a thin film semiconductor device according to the present invention comprises placing a liquid material for forming a semiconductor film on a substrate as a droplet, and the solid content concentration of the liquid material is the droplet. A step of forming an island-shaped semiconductor film by drying so as to reach a saturation concentration almost simultaneously as a whole, a step of forming a gate insulating film covering at least a portion of the semiconductor film serving as a channel region, and the gate insulation Forming a gate electrode on the film.

  According to such a configuration, since the semiconductor film constituting the thin film semiconductor device is formed from a liquid material, the manufacturing cost can be suppressed and the throughput can be increased as compared with the case where the thin film is formed using the CVD method. be able to.

  Here, in the step of forming the gate insulating film, a liquid material for forming the gate insulating film is disposed on the semiconductor film as a droplet, and the solid content concentration of the liquid material is the entire droplet. A gate insulating film may be formed so as to cover at least a portion to be a channel region of the semiconductor film by drying so as to reach a saturation concentration substantially at the same time. Thus, the gate insulating film can be made substantially constant by forming the gate insulating film from the liquid material together with the semiconductor film.

  The gate insulating film preferably has a larger diameter than the semiconductor film and covers the entire semiconductor film, and the semiconductor film preferably has a diameter of 4 to 10 μm.

  The thin film semiconductor device according to the present invention includes a substantially circular semiconductor film having a first conductive region, a second conductive region, and a channel region, a gate insulating film covering at least the channel region, and the gate insulation. And a substantially rectangular gate electrode formed on the film.

  In the above configuration, it is preferable that the gate insulating film has a larger diameter than the semiconductor film and is an insulating film that covers the entire semiconductor film, and the diameter of the semiconductor film is 4 to 10 μm. The aspect set to is preferable.

  A thin film semiconductor device having such characteristics may be applied to an electro-optical device or an electronic device. Here, the electro-optical device is, for example, a device including a liquid crystal element, an electrophoretic element having a dispersion medium in which electrophoretic particles are dispersed, an EL element, and the like, and the thin film semiconductor device is applied to a drive circuit or the like. Refers to the device. The electronic device refers to a general device having a certain function provided with the thin film semiconductor device according to the present invention, and includes, for example, an electro-optical device and a memory. The configuration is not particularly limited, but for example, an IC card, a mobile phone, a video camera, a personal computer, a head-mounted display, a rear-type or front-type projector, a fax machine with a display function, a digital camera finder, a portable TV, A DSP device, PDA, electronic notebook, electronic bulletin board, advertising display, etc. are included.

  Before describing embodiments according to the present invention, the basic principle of the present invention will be described first.

<Basic principle>
FIG. 1 is a diagram schematically showing a characteristic drying process of droplets according to the present invention.
In the film forming method shown in FIG. 1, a liquid film is applied (arranged) as droplets L on a substrate and dried under predetermined drying conditions (described later) to form a dry film (thin film). Here, FIG. 2 is a diagram schematically showing a general drying process of droplets. In general, the droplet L arranged on the substrate is rapidly dried at the edge (see the dotted line portion in FIG. 2). For this reason, in the initial stage of drying, the liquid rapidly evaporates at the edge of the droplet, and the solid concentration tends to increase. At this time, when the solid content concentration at the edge of the droplet reaches the saturation concentration, the solid content locally precipitates at the edge. Then, a state in which the edge portion of the droplet is pinned by the precipitated solid content is generated (hereinafter, “pinning”). As a result, a dry film M2 in which the contraction of the droplets (contraction of the outer shape) accompanying the subsequent drying is suppressed is formed (see FIG. 2).

On the other hand, in the present invention, drying conditions (such as substrate heating conditions) for the droplets are determined so that the solid content concentration of the liquid material reaches the saturated concentration almost simultaneously throughout the droplets, so that pinning does not occur during drying. The droplet is contracted (hereinafter “depinning”).
Specifically, by defining the above drying conditions, a convection including a flow from the center to the edge and a flow from the edge to the center is continuously formed in the droplet as shown in FIG. The solid content concentration in the droplet is made uniform by suppressing the local solid content concentration increase at the edge. Thereafter, when the solid content concentration of the entire droplet reaches the saturation concentration almost simultaneously, precipitation starts almost simultaneously in the entire droplet, and a substantially circular dry film M1 is formed (see FIG. 1). Hereinafter, embodiments using the depinning phenomenon will be described with reference to the drawings.

A. First Embodiment FIGS. 3 to 5 are views showing a manufacturing process of a TFT (thin film semiconductor device) according to the first embodiment. FIGS. 4 (a) to 4 (c) are respectively the same as FIG. ) To FIG. 3C are sectional views taken along line AA ′.

A-1. Formation of Semiconductor Film First, a liquid material such as liquid silicon containing cyclopentasilane (hereinafter referred to as a semiconductor material) is applied to a substrate 10 such as a glass substrate by a droplet discharge method (inkjet method), and then the semiconductor material is formed. The island-shaped (substantially circular shape in this case) semiconductor film 11 is dried by setting the drying conditions so that the solid concentration reaches the saturation concentration almost simultaneously in the entire droplet (in other words, the depinning phenomenon occurs). (See FIGS. 3A and 4A). More specifically, the drying conditions and the like are determined so that the thickness of the semiconductor film 11 is about 40 to 100 nm and the diameter R1 of the semiconductor film 11 is about 4 to 10 μm. In general, the electrical characteristics of a TFT are improved as the semiconductor film 11 is thinner. However, when the thickness is more than a certain level, there is a problem that the crystallinity is lowered and the resistance of the source / drain regions is increased. In order to prevent such a problem, in this embodiment, the drying conditions are set so that the film thickness of the semiconductor film 11 is about 40 to 100 nm and the diameter R1 of the semiconductor film 11 is about 4 to 10 μm. It has established. Specific drying conditions may be determined based on the material of the semiconductor material, the solid content concentration, the drying speed of the droplets, and the like. Before forming the semiconductor film 11, a base insulating film made of a silicon oxide film having a thickness of about 200 to 500 nm using TEOS (tetraethoxylane) or oxygen gas as a raw material may be formed on the substrate 10.

A-2. Formation of Gate Insulating Film Next, a gate insulating film 12 is formed so as to cover the entire surface of the semiconductor film 11 formed as described above (see FIGS. 3B and 4B). Specifically, after applying (disposing) a liquid material in which perhydropolysilazane is dissolved in an organic solvent (for example, a 10% xylene solution) so as to cover the entire surface of the semiconductor film 11 by a droplet discharge method (inkjet method), Similarly to the above, the island-shaped (substantially circular shape) gate insulating film 12 is formed by determining and drying the drying conditions so that the depinning phenomenon occurs. More specifically, a gate insulating film 12 having a diameter R2 larger than the diameter R1 of the substantially circular semiconductor film 11 and covering the entire surface of the semiconductor film 11 is formed (FIG. 3B). (Refer FIG.4 (b)). Instead of (or in addition to) appropriately setting the drying conditions, the material and application amount of the liquid material may be set as appropriate.

A-3. Formation of Gate Electrode Next, a substantially rectangular gate electrode 13 is formed on the gate insulating film 12 covering the semiconductor film 11 (see FIGS. 3C and 4C). Specifically, the gate electrode 13 is formed by forming a metal thin film such as gate tantalum, chromium, aluminum or the like by sputtering and then patterning it into a desired shape (substantially rectangular in this embodiment). In forming the gate electrode 13, a droplet discharge method, a CVD method, or the like may be used instead of the sputtering method.

A-4. Formation of Source / Drain Region After that, impurity ions (such as phosphorus ions) I are implanted using the gate electrode 13 as a mask, thereby introducing the impurity ions into the semiconductor film 11 (see FIG. 5D). Thereby, a source region (first conductive region) 11s and a drain region (second conductive region) 11d having a high impurity concentration are formed in a self-aligned manner, and a channel region is formed between the source region 11s and the drain region 11d. 11c is formed.

A-5. Formation of Interlayer Insulating Film After an interlayer insulating film 14 containing silicon such as a silicon oxynitride film or a silicon oxide film is formed on the substrate 10 on which the gate electrode 13 is formed (see FIG. 5E), photo Contact holes are formed at predetermined source electrode positions and drain electrode positions by patterning by lithography or the like. Note that the interlayer insulating film 14 may be formed using a spin coating method or the like.

A-6. Formation of Electrode Subsequently, after forming a conductive film such as an aluminum film, a chromium film, or a tantalum film on the interlayer insulating film 14 (for example, a thickness of 200 nm to 800 nm), patterning is performed at the formation position of the source electrode and the drain electrode. A source electrode 15s and a drain electrode 15d are formed by forming a mask (not shown) and performing patterning (see FIG. 5F). By executing the series of steps described above, a TFT having good electrical characteristics is formed.

As described above, according to this embodiment, since the semiconductor film constituting the TFT is formed from a liquid material, the manufacturing cost can be reduced compared to the case where a thin film is formed using the CVD method. , Throughput can be increased.
Further, by forming both the semiconductor film and the gate insulating film from a liquid material, the thickness of the gate insulating film can be made substantially constant.

  In the embodiment described above, the gate insulating film 12 having the diameter R2 larger than the diameter R1 of the substantially circular semiconductor film 11 and covering the entire surface of the semiconductor film 11 is formed (FIG. 3, FIG. 3). As shown in FIG. 4 and FIG. 6, a gate insulating film 12 ′ may be formed so as to cover the channel region of the semiconductor film 11 (the region facing the gate electrode 13 in the semiconductor film 11).

  In the above-described embodiment, the case where the substantially circular semiconductor film 11 is formed is illustrated. However, for example, the semiconductor material 11 is substantially elliptically formed by continuously applying the semiconductor material while being moved by a droplet discharge method. Alternatively, a substantially linear semiconductor film 11 may be formed. In short, the semiconductor film 11 may be formed using the depinning phenomenon, and how the shape of the semiconductor film 11 is set is arbitrary. Of course, this is not limited to the semiconductor film 11, and a substantially elliptical gate insulating film 12 or a substantially linear gate insulating film 12 may be formed.

B. Second Embodiment In the above-described embodiments, the semiconductor film 11 and the like are formed using a droplet discharge method (inkjet method), but other methods using a liquid material (for example, a spinless method, a dip coating method, a spin coating method, etc.) Method). Alternatively, a combination of a film forming method using a liquid material, a CVD method, a sputtering method, or the like may be used. FIG. 7 is a diagram for explaining a method of forming the semiconductor film 11 using the spinless method.

  The nozzle head 500 discharges a semiconductor material and is fixedly supported by a holding member (not shown). The protrusions 510 of the nozzle head 500 are arranged so as to be parallel to the surface of the substrate 610 while maintaining a gap G. The protrusion 510 is provided with a discharge port (not shown) set to a length slightly smaller than the length (width) of the substrate 610 in the Y direction, and in the X direction according to an instruction from a controller (not shown). A semiconductor material is discharged (applied) onto the surface of the substrate 610 to be conveyed, thereby forming a semiconductor film. 7 illustrates the case where the discharge port of the nozzle head 500 faces downward, the discharge port is directed upward according to the physical properties and flow characteristics of the semiconductor material, and in this state, the semiconductor is formed on the surface of the substrate 610. The material may be discharged.

  Although the method for forming a semiconductor film using the spinless method has been described above, the semiconductor film may be formed by a dip coating method or a droplet discharge method. When a semiconductor film is formed using a semiconductor material including a dip coating method, it is desirable to perform a treatment for making a region where the semiconductor film is to be formed lyophilic as a pretreatment. Examples of such processing include processing such as oxygen plasma and UV irradiation. The substrate that has been subjected to such pretreatment may be immersed in a semiconductor material, and then pulled up and dried to apply the semiconductor material onto the substrate. In forming the semiconductor film, the same type of coating method may be used, but different types of coating methods may be used in appropriate combination. For example, when the semiconductor material is applied to the substrate a plurality of times, it is applied at least once by the droplet discharge method, at least the first time by the spinless method, or at least the first time by the spin coating method. May be applied.

C. Third Embodiment FIG. 8 is a connection diagram of an organic EL display device 100 which is a kind of electro-optical device according to a third embodiment.
A pixel circuit formed in each pixel region includes a light emitting layer OELD that can emit light by an electroluminescence effect, a storage capacitor that stores a current for driving the light emitting layer OELD, and TFTs 111 to 114 according to the present invention. On the other hand, each of the drive circuits 101 and 102 formed in the drive circuit region includes a plurality of TFTs according to the present invention. From the drive circuit 101, the scanning line Vsel and the light emission control line Vgp are supplied to the corresponding pixel circuits, and from the drive circuit 102, the data line Idata and the power supply line Vdd are supplied to the corresponding pixel circuits. By controlling the scanning line Vsel and the data line Idata, light emission by the corresponding light emitting units OELD can be controlled. The drive circuit is an example of a circuit in the case where an electroluminescent element is used as a light emitting element, and other circuit configurations are possible.

D. Fourth Embodiment FIG. 9 is a diagram illustrating an electronic device according to a fourth embodiment.
FIG. 9A shows a mobile phone manufactured by the manufacturing method of the present invention. The mobile phone 330 includes an electro-optical device (display panel) 100, an antenna unit 331, an audio output unit 332, an audio input unit 333, and An operation unit 334 is provided. The present invention is applied to, for example, the manufacture of a substrate on which a pixel circuit and a driving circuit in the display panel 100 are arranged. FIG. 9B shows a video camera manufactured by the manufacturing method of the present invention. The video camera 340 includes an electro-optical device (display panel) 100, an image receiving unit 341, an operation unit 342, and an audio input unit 343. ing. The present invention is applied to, for example, the manufacture of a substrate on which a pixel circuit and a driving circuit in the display panel 100 are arranged.

  FIG. 9C shows an example of a portable personal computer manufactured by the manufacturing method of the present invention. The computer 250 includes an electro-optical device (display panel) 100, a camera unit 351, and an operation unit 352. . The present invention is applied to, for example, the manufacture of a substrate on which a pixel circuit and a driving circuit in the display panel 100 are arranged.

  FIG. 9D shows an example of a head mounted display manufactured by the manufacturing method of the present invention. The head mounted display 360 includes an electro-optical device (display panel) 100, a band unit 361, and an optical system storage unit 362. I have. The present invention is applied to, for example, the manufacture of a substrate on which a pixel circuit and a driving circuit in the display panel 100 are arranged. FIG. 9E shows an example of a rear projector manufactured by the manufacturing method of the present invention. The projector 370 includes an electro-optical device (light modulator) 100, a light source 372, a combining optical system 373, a mirror 374, 375 is provided in the housing 371. The present invention is applied to, for example, manufacturing a substrate on which a pixel circuit and a drive circuit in the optical modulator 100 are arranged. FIG. 9F shows an example of a front type projector manufactured by the manufacturing method of the present invention. The projector 380 includes an electro-optical device (image display source) 100 and an optical system 381 in a housing 382, and an image is displayed. Can be displayed on the screen 383. The present invention is applied to, for example, manufacturing a substrate on which a pixel circuit and a drive circuit in the image display source 100 are arranged.

  The present invention is not limited to the above example and can be applied to the manufacture of all electronic devices. For example, the present invention can also be applied to a fax machine with a display function, a finder for a digital camera, a portable TV, a DSP device, a PDA, an electronic notebook, an electric bulletin board, a display for advertisement announcement, an IC card, and the like. The present invention is not limited to the above-described embodiments, and various modifications and changes can be made within the scope of the gist of the present invention.

It is the figure which showed typically the drying process characteristic of the droplet concerning this invention. It is the figure which showed typically the drying process of the general droplet. It is a figure which shows the manufacturing process of TFT which concerns on 1st Embodiment. It is a figure which shows the manufacturing process of TFT concerning the embodiment. It is a figure which shows the manufacturing process of TFT concerning the embodiment. It is the figure which illustrated the shape of other gate insulating films concerning the embodiment. It is a figure for demonstrating the formation method of the semiconductor film using the spinless method which concerns on 2nd Embodiment. FIG. 10 is a diagram illustrating a configuration of an electro-optical device according to a third embodiment. It is the figure which illustrated the composition of each electronic device concerning a 4th embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Substrate, 11 ... Semiconductor film, 12, 12 '... Gate insulating film, 13 ... Gate electrode, 14 ... Interlayer insulating film, 11s ... Source region, 11d ... Drain region, 11c ... channel region, 15s ... source electrode, 15d ... drain electrode.

Claims (4)

The liquid material for forming the semiconductor film is placed on the substrate as droplets, and dried so that the solid content concentration of the liquid material reaches the saturation concentration almost simultaneously in the entire droplet, thereby forming an island-shaped semiconductor film. Forming, and
Forming a gate insulating film covering at least a portion to be a channel region of the semiconductor film;
Forming a gate electrode on the gate insulating film. A method for manufacturing a thin film semiconductor device, comprising:   2. The method of manufacturing a thin film semiconductor device according to claim 1, wherein in the step of forming the gate insulating film, a liquid material for forming the gate insulating film is disposed on the semiconductor film as droplets, and the liquid is formed. A thin film characterized by forming a gate insulating film covering at least a portion to be a channel region of the semiconductor film by drying so that a solid content concentration of the material reaches a saturated concentration almost simultaneously in the entire droplet A method for manufacturing a semiconductor device.   3. The method of manufacturing a thin film semiconductor device according to claim 2, wherein the gate insulating film is an insulating film having a larger diameter than the semiconductor film and covering the entire semiconductor film. Device manufacturing method. 4. The method of manufacturing a thin film semiconductor device according to claim 1, wherein a diameter of the semiconductor film is set to 4 to 10 [mu] m.

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