JP2007042723A - Silicon film manufacturing method, thin-film semiconductor device manufacturing method, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing technique for reducing the number of steps required for forming a semiconductor film. <P>SOLUTION: The silicon film manufacturing method utilizing a liquid process includes a first step for applying a liquid material (12) containing a silicon atom on a substrate (10), a second step for forming a silicon film (14) to a part irradiated with a laser beam by locally emitting the laser beam to the liquid material applied in the first step, and a third step for removing the liquid material at the part not irradiated with the laser beam in the second step. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a silicon film, a method of manufacturing a thin film semiconductor element including the manufacturing method, and an electronic apparatus including the thin film semiconductor element.

  Conventionally, a method for manufacturing a semiconductor film using a liquid material has been proposed in order to achieve a reduction in manufacturing cost (see, for example, Patent Documents 1 and 2). In the manufacturing methods described in these documents, after applying a liquid material containing silicon atoms on a substrate, the semiconductor film is patterned through steps of baking, crystallization, photolithography, etching, and resist peeling.

  In the above-mentioned known technique, although the effect of reducing the manufacturing cost can be obtained for the film forming process of the semiconductor film on the substrate, the other processes are the same as the conventional manufacturing method. For this reason, the semiconductor film is formed, baked, and crystallized over a wide range even though most of the film is finally removed by etching, so that productivity, material cost, energy consumption, etc. There is room for further improvement.

  In response to such a demand, a method of directly drawing a liquid material containing silicon atoms by a droplet discharge method has been studied. According to such a method, each step (photolithography, etching, resist stripping) required for patterning the semiconductor film can be omitted, so that the number of steps can be reduced. However, since the size of the pattern drawn by the droplet discharge method is on the order of several tens of μm, it is not suitable for forming a finer pattern, for example, when forming a semiconductor film constituting a thin film transistor.

International Publication No. 00/59040 Pamphlet International Publication No. 00/59041 Pamphlet

  Therefore, an object of the present invention is to provide a manufacturing technique that can reduce the number of steps required for forming a semiconductor film.

  The first aspect of the present invention is a method of manufacturing a silicon film using a liquid process, the first step of applying a liquid material containing silicon atoms on a substrate, and the liquid applied in the first step. A second step of forming a silicon film on the portion irradiated with the laser beam by locally irradiating the material with the laser beam, and the portion of the portion not irradiated with the laser beam in the second step And a third step of removing the liquid material.

  According to such a manufacturing method, only a portion irradiated with laser light is solidified and converted into a silicon film, and the other portions are not solidified (liquid or semi-solid state). ). Therefore, it is possible to collectively perform a process of baking the liquid material to convert it into a silicon film and a process of patterning the silicon film into a desired shape at a desired position. As a result, the number of steps required for forming the semiconductor film can be reduced. Further, according to local pattern drawing using laser light, it is possible to form a fine pattern with a low order even when direct drawing using a droplet discharge method is performed.

  In the first step described above, various film forming methods such as a spin coating method can be adopted, but it is particularly preferable to apply the liquid material by a droplet discharge method.

  As a result, the liquid material can be selectively applied only to the minimum necessary range including the region where the silicon film is to be formed, so that the amount of liquid material used can be further reduced. Moreover, the usage-amount of the solvent etc. which are required for the removal of the liquid material in a 3rd process can also be reduced.

  Preferably, in the second step, the laser beam is irradiated to the same portion in a plurality of times.

  Thereby, since the irradiation energy of the laser beam at each time can be reduced, the film can be formed more satisfactorily.

  Preferably, in the second step, the laser beam is irradiated a plurality of times by increasing the energy density of the laser beam each time. That is, first, the liquid material is gradually solidified by irradiating a laser beam having a relatively low energy density, and thereafter, a laser beam having a higher energy density is irradiated.

  Thereby, it is possible to reliably avoid the divergence of the liquid material and perform good film formation.

  Preferably, in the second step, the laser light is set to a first energy density having a size required for solidification of the liquid material and irradiated at least once, and then the laser light is applied to the first energy density. Irradiation is performed one or more times at a second energy density that is higher than the energy density and that is necessary for crystallization of the silicon film.

  Thereby, a polycrystalline silicon film is obtained. When the energy density of the laser beam is set so as not to reach the second energy density, an amorphous silicon film can be obtained.

  The second aspect of the present invention is a method for manufacturing a thin film semiconductor device comprising the manufacturing method according to the first aspect of the present invention. Here, the “thin film semiconductor element” refers to a general element configured using a semiconductor film, and examples thereof include active elements such as thin film transistors and thin film diodes, and passive elements such as resistors and capacitors.

  According to such a manufacturing method, it is possible to reduce the number of steps required for manufacturing a thin film semiconductor element.

  The third aspect of the present invention is an electronic device including the thin film semiconductor element according to the second aspect of the present invention. Here, “electronic device” means a general device including an electric circuit, a display unit, etc., for example, an IC card, a mobile phone, a video camera, a personal computer, a head mounted display, a television device, a facsimile, a digital still camera. PDA, electronic notebook, etc.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a process cross-sectional view illustrating a silicon film manufacturing method and a thin film transistor manufacturing method using the silicon film according to an embodiment. FIG. 2 is a partial process cross-sectional view illustrating another aspect of the silicon film manufacturing method.

(Liquid material application process)
First, a liquid material 12 containing silicon atoms is applied over a substrate 10 such as a glass substrate (FIG. 1A). As a method for applying the liquid material 12, various methods such as a spin coat method, a roll coat method, a curtain coat method, a dip coat method, a spray method, and a droplet discharge method can be employed. In particular, when the droplet discharge method is adopted, in addition to the case where the liquid material 12 is applied to the entire surface of the substrate 10 as shown in FIG. 1A, the minimum necessary amount as shown in FIG. The liquid material 12 can be applied only to a limited area. Here, the “minimum necessary region” refers to a region substantially equivalent to a region where a silicon film 14 to be described later is to be formed.

Here, as the liquid material 12 used in this step, the general formula Si _n X _m (n is an integer of 5 or more, m is an integer of n, 2n-2, or 2n, X is a hydrogen atom and / or a halogen atom). What dissolved the silicon compound which has a ring system represented by this in the solvent is used suitably. In particular, as the silicon compound of Si _n X _m , those in which n is 5 or more and 20 or less are preferable, and those in which n is 5 or 6 are more preferable. Examples of such silicon compounds include cyclopentasilane and silylcyclopentasilane. Further, as the solvent, those having a vapor pressure of 0.001 to 200 mmHg at room temperature are usually used. Such a solvent is not particularly limited as long as it dissolves a silicon compound and does not react with the solvent, but n-hexane, n-heptane and the like are preferably used. Note that suitable examples of the silicon compound and the solvent other than those described above are described in Patent Document 1 described above, and description thereof is omitted here.

(Laser irradiation process)
Next, by irradiating laser light locally on the liquid material 12 applied on the substrate 10 in the above-described process, a silicon film 14 is formed in a portion irradiated with the laser light (FIG. 1B ), FIG. 2 (B)). At this time, the portion of the liquid material 12 that is not irradiated with the laser light is not solidified and is kept in a liquid state.

  Here, as a laser beam used in this process, for example, a pulsed laser having a wavelength of about several hundreds of nanometers can be cited. More specifically, various lasers such as an excimer laser such as a YAG laser, an argon laser, a carbon dioxide laser, XeF, XeCl, XeBr, KrF, KrCl, ArF, and ArCl can be used as a light source. The laser light output from these light sources is condensed so that the beam diameter is about 10 μm, and the region where the silicon film 14 is to be formed is irradiated. Moreover, you may use each branch beam obtained by branching the laser beam output from a light source into about 100 with a diffractive optical element. At this time, it is preferable to irradiate the laser beam in multiple times to the same location. This is because the irradiation energy of the laser beam at each time can be reduced, so that the film can be formed more satisfactorily.

Furthermore, it is also preferable that the laser beam irradiation in this step is performed by increasing the energy density of the laser beam each time. For example, the liquid material 12 is gradually solidified by irradiating a laser beam having a relatively low energy density (for example, about 50 mJ / cm ² ) at first, and then a laser beam having a higher energy density (for example, 150 mJ / cm ² ). ² or more). Thereby, the divergence of the liquid material 12 can be avoided reliably and good film formation can be performed.

More specifically, first, the laser beam is set to the first energy density of a size required for solidification of the liquid material 12 and irradiated at least once, and then the laser beam is larger than the first energy density, Further, it is preferable to irradiate at least once with the second energy density set to a size required for crystallization of the silicon film. Thereby, a polycrystalline silicon film 14 is obtained. When the energy density of the laser beam is set so as not to reach the second energy density, an amorphous silicon film 14 is obtained. Here, specific numerical values of the first energy density and the second energy density vary depending on the wavelength of the laser beam. For example, when a pulsed laser beam having a wavelength of 532 nm is used, In general, the first energy density is 50 mJ / cm ² and the second energy density is 150 to 200 mJ / cm ² or more.

  In addition, although irradiation of the laser beam in this process may perform pattern exposure through a photomask, the method of direct irradiation (direct drawing) is more preferable. Examples of the direct drawing method include a method using a DMD (Digital Micromirror Device) and a method using a laser beam branched into a large number with a diffractive optical element as described above. Through these methods, throughput can be improved.

(Liquid material removal process)
Next, the portion of the liquid material 12 that has not been irradiated with the laser light in the above process is removed (FIG. 1C). As described above, since the liquid material 12 in the portion is kept in a non-solidified state (liquid or semi-solid), it can be easily removed by washing with an organic solvent and pure water.

  As described above, the silicon film 14 patterned in a desired shape at a desired position on the substrate 10 is obtained. Using this silicon film 14, a thin film semiconductor element such as a thin film transistor can be manufactured. Hereinafter, a method for manufacturing the thin film transistor will be specifically described. Here, a coplanar thin film transistor is illustrated.

(Insulating film formation process)
Next, an insulating film 16 that covers the silicon film 14 is formed over the substrate 10 (FIG. 1D). For example, the insulating film 16 made of a silicon oxide film can be formed by PECVD. Specifically, tetraethoxysilane (TEOS) and oxygen (O ₂ ) are used as source gases, the flow rates are 50 sccm, 5 slm, the ambient temperature is 350 ° C., the RF power is 1.3 kW, and the pressure is 200 Pa. Then, a silicon oxide film is formed. In this case, the deposition rate is about 30 nm / min, and a good silicon oxide film having a breakdown voltage characteristic suitable for an insulating film can be obtained.

(Gate electrode formation process, ion implantation process)
Next, after forming a metal thin film such as tantalum or aluminum by sputtering, patterning is performed to form a gate electrode 18 at a predetermined position on the insulating film 16 (FIG. 1E). Next, impurity ions serving as donors or acceptors are implanted into the silicon film 14 using the gate electrode 18 as a mask. As a result, a channel formation region is formed below the gate electrode 18, and a source / drain region is formed in other portions (portions where ions have been implanted). When manufacturing an NMOS transistor, for example, phosphorus (P) as an impurity element is implanted into the source / drain region at a concentration of 1 × 10 ¹⁶ cm ⁻² . Thereafter, the XeCl excimer laser is irradiated at an irradiation energy density of about 200 to 400 mJ / cm ² or heat treatment is performed at a temperature of about 250 ° C. to 450 ° C. to activate the impurity element.

(Insulating film forming process, source / drain electrode forming process)
Next, an insulating film 20 is formed over the insulating film 16 and the gate electrode 18 (FIG. 1F). For example, the insulating film 20 made of a silicon oxide film of about 500 nm can be formed by PECVD. Thereafter, contact holes that penetrate the insulating films 16 and 20 and reach the source / drain regions of the silicon film 14 are formed, and source / drain electrodes 22 are formed in the contact holes and on the insulating film 20. The source / drain electrode 22 can be formed, for example, by depositing aluminum by sputtering and patterning.

  Through the above steps, a thin film transistor is formed. In the present embodiment, a thin film transistor is illustrated as an example of the thin film semiconductor element, but other thin film semiconductor elements can be formed.

  Next, an organic EL device will be described as a specific example of a device including the thin film transistor according to the above-described embodiment.

  FIG. 3 is a schematic plan view of the wiring structure of the organic EL device. The organic EL device 100 shown in FIG. 3 includes a plurality of scanning lines 101, a plurality of signal lines 102 arranged orthogonal to the scanning lines, a plurality of power supply lines 103 extending in parallel to the signal lines 102, and each scanning line. 101 and a pixel region A provided in the vicinity of the intersection of each signal line 102. That is, the organic EL device 100 of this example is an active matrix display device in which a plurality of pixels are arranged in a matrix.

  Each scanning line 101 is connected to a scanning line driving circuit 105 including a shift register and a level shifter. Each signal line is connected to a data line driving circuit 104 including a shift register, a level shifter, a video line, and an analog switch. In each pixel region A, a switching transistor 112 to which a scanning signal is supplied to the gate via the scanning line 101, a holding capacitor 111 for holding a pixel signal supplied from the signal line 102 via the switching transistor 112, A driving transistor 113 to which the pixel signal held by the holding capacitor 111 is supplied to the gate and a driving current from the power source line 103 when electrically connected to the power source line 103 via the driving transistor 113 are supplied. A flowing-in pixel electrode (cathode) and a functional layer 110 sandwiched between the pixel electrode and a counter electrode (anode) are provided. The pixel electrode, the counter electrode, and the functional layer 110 constitute a light emitting element (organic EL element). The functional layer 110 includes a hole transport layer, a light emitting layer, an electron injection layer, and the like.

  In the organic EL device 100, when the scanning line 101 is driven and the switching transistor 112 is turned on, the potential of the signal line 102 at that time is held in the holding capacitor 111, and the driving is performed according to the state of the holding capacitor 111. The on / off state of the transistor 113 is determined. Then, current flows from the power supply line 103 to the pixel electrode through the channel of the driving transistor 113, and further current flows to the anode through the functional layer 110. The functional layer 110 emits light according to the amount of current that flows. By controlling the light emission state of each functional layer 110, desired image display can be performed.

  The thin film transistor according to this embodiment can be used as the switching transistor 112 and the driving transistor 113 described above, or as a circuit element for configuring the scanning line driving circuit 105 and the data line driving circuit 104. The organic EL device is merely an example, and the thin film transistor according to the present embodiment can be used to configure a liquid crystal device, an electrophoresis device, and various other devices.

  Next, a specific example of an electronic apparatus including the organic EL device 100 described above will be described.

  FIG. 4 is a perspective view illustrating a specific example of an electronic apparatus provided with the organic EL device 100. FIG. 4A is a perspective view illustrating a mobile phone which is an example of an electronic device. The cellular phone 1000 includes a display unit 1001 configured using the organic EL device 100 according to the present embodiment. FIG. 4B is a perspective view illustrating a wrist watch which is an example of an electronic apparatus. The wristwatch 1100 includes a display unit 1101 configured using the organic EL device 100 according to the present embodiment. FIG. 4C is a perspective view illustrating a portable information processing device 1200 which is an example of an electronic device. The portable information processing device 1200 includes an input unit 1201 such as a keyboard, a main body unit 1202 in which a calculation unit, a storage unit, and the like are stored, and a display unit 1203 configured using the organic EL device 100 according to the present embodiment. I have.

  As described above, according to the present embodiment, of the liquid material applied on the substrate, only the portion irradiated with the laser light is converted into the silicon film, and the other portions are not solidified (liquid or semi-solid state). ). Therefore, it is possible to collectively perform a process of baking the liquid material to convert it into a silicon film and a process of patterning the silicon film into a desired shape at a desired position. As a result, the number of steps required for forming the semiconductor film can be reduced. Further, according to local pattern drawing using laser light, it is possible to form a fine pattern with a low order even when direct drawing using a droplet discharge method is performed.

  In addition, this invention is not limited to the content of the said embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention.

It is process sectional drawing explaining the manufacturing method of a silicon film, and the manufacturing method of the thin-film transistor using this silicon film. It is a partial process sectional view explaining other modes of a manufacturing method of a silicon film. It is a plane schematic diagram of the wiring structure of an organic EL device. It is a perspective view which shows the specific example of the electronic device provided with the organic EL apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Substrate, 12 ... Liquid material, 14 ... Silicon film, 16 ... Insulating film, 18 ... Gate electrode, 20 ... Insulating film, 22 ... Source / drain electrode

Claims (7)

A first step of applying a liquid material containing silicon atoms on a substrate;
A second step of forming a silicon film on the portion irradiated with the laser beam by locally irradiating the liquid material applied in the first step with a laser beam;
A third step of removing the liquid material in a portion not irradiated with the laser beam in the second step;
A method for manufacturing a silicon film.   2. The method of manufacturing a silicon film according to claim 1, wherein in the first step, the liquid material is applied by a droplet discharge method.   2. The method of manufacturing a silicon film according to claim 1, wherein in the second step, the laser beam is irradiated to the same portion in a plurality of times.   4. The method of manufacturing a silicon film according to claim 3, wherein in the second step, the energy density of the laser beam is increased each time and the laser beam is irradiated a plurality of times.   In the second step, the laser beam is set to a first energy density having a size required for solidification of the liquid material and irradiated at least once, and then the laser beam is irradiated from the first energy density. 5. The method of manufacturing a silicon film according to claim 3, wherein the second energy density is set to a second energy density that is large and required for crystallization of the silicon film and is irradiated at least once.   A method for manufacturing a thin film semiconductor element, comprising the method for manufacturing a silicon film according to claim 1. An electronic apparatus comprising the thin film semiconductor element manufactured by the manufacturing method according to claim 6.

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