JP2007134481A - Method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To use metal fine grains which have a diameter such as nano-scale and are coated with a protection film by an organic molecule without using a large-scale high vacuum evaporator, and to form a thin electrode of a nano-scale thickness at a high conductivity. <P>SOLUTION: A semiconductor device has a conductive path 24 formed with fine grains made of a conductor or a semiconductor and an organic semiconductor molecule bonded to the fine grains on a substrate 11, and an electrode 17 connected to the conductive path 24. In a method for manufacturing the semiconductor device; the step of forming the electrode 17 comprises the steps of forming a mask layer 12 open on a region where the electrode 17 is formed on the substrate 11, arranging metal fine grains 15 on a surface of the substrate 11 in an opening of the mask layer 12 to form the a metal grain layer 16, and melting the metal grain layer 16 to form the metal layer (electrode) 17. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device, in which it is easy to manufacture a thin electrode having a nanoscale thickness used by a semiconductor device.

  Currently, research and development are being actively carried out on next-generation semiconductor devices using basic scale units and materials with nanoscale size. One of its main motivations is to avoid the limitations of semiconductor device scaling that will be encountered in the near future through the use of nanoscale sized materials. In addition, a simple method that does not require a large-scale manufacturing apparatus such as a high-vacuum vapor deposition apparatus is being sought in order to manufacture a cheaper device than the current semiconductor device.

  For example, a field effect transistor in which a semiconductor layer is formed by coating poly (hexylthiophene) (P3HT) or a pentacene precursor chloroform solution is a good example. In addition, a transistor having a conductive layer in which fine particles are networked with organic molecules, such as a method of immersing or casting a fine particle dispersion into a substrate, or a method of transferring a Langmuir film made of fine particles to a substrate, is an easy method. Produced and found promising (for example, see Patent Documents 1 and 2).

  However, if a large-scale manufacturing apparatus is not required at all, this is not actually the case. In particular, the conventional vacuum deposition apparatus is used for the production of the electrode part, and the cost is low. It is a factor that increases. Further, as a problem of electrode part formation, when a single layer film made of fine particles is formed on a substrate, breakage occurs at the contact part between the electrode having a thickness of about 50 nm and the single layer film, and the thickness is further increased. There is also a need to produce an electrode with a reduced size without using a large-scale apparatus.

JP 2004-088090 A International Publication Number WO 2004/006377 A1 Brochure

  The problem to be solved is that the electrode formed by a conventional manufacturing method such as vacuum deposition is thick, and when a single layer film made of fine particles is formed on the electrode part, the contact between the electrode and the single layer film It is that a break occurs in the part.

  The present invention is capable of forming a thin electrode capable of forming a single-layer film made of fine particles on an electrode without using a large-scale manufacturing apparatus such as a high-vacuum evaporation apparatus. The challenge is to make it possible.

  A method of manufacturing a semiconductor device according to the present invention includes a semiconductor device having a conductive path formed by fine particles made of a conductor or a semiconductor and organic semiconductor molecules bonded to the fine particles, and an electrode connected to the conductive path on a substrate. The step of forming the electrode includes a step of forming a mask layer having an opening on a region where the electrode is to be formed on the substrate, and metal fine particles on the surface of the substrate in the opening of the mask layer. It comprises a step of forming a metal particle layer by disposing, and a step of dissolving the metal fine particle layer to form a metal layer.

  This method of manufacturing a semiconductor device includes a step of forming a metal particle layer by disposing metal fine particles on the surface of the substrate in the opening of the mask layer, and a step of dissolving the metal fine particle layer to form a metal layer. For example, an electrode having a film thickness of the order of nm is formed. As a result, when a single-layer film made of fine particles is formed on the electrode, it is formed without causing breakage.

  A method of manufacturing a semiconductor device according to the present invention includes a semiconductor device having a conductive path formed by fine particles made of a conductor or a semiconductor and organic semiconductor molecules bonded to the fine particles, and an electrode connected to the conductive path on a substrate. The method of forming the electrode includes the step of patterning a paste material in which metal fine particles covered with a protective film made of organic molecules are dispersed on the substrate on the electrode forming region, and the organic And forming the electrode by fusing metal fine particles by desorbing molecules.

  In this method of manufacturing a semiconductor device, a process of patterning a paste material in which metal fine particles covered with a protective film made of organic molecules are dispersed on an electrode forming region and metal fine particles are fused by detaching organic molecules. Thus, an electrode having a film thickness of, for example, nm order is formed. As a result, when a single-layer film made of fine particles is formed on the electrode, it is formed without causing breakage.

  The semiconductor device manufacturing method of the present invention uses nanoscale metal fine particles covered with a protective film of organic molecules, for example, so that the nanoscale thickness can be reduced without using a large-scale high-vacuum deposition apparatus or the like. There is an advantage that a thin electrode can be formed. Thereby, a single layer film can be formed on the electrode without causing breakage. Further, since a high-temperature process is not used, there is an advantage that it is possible to perform electrode formation on a plastic substrate that is likely to be deformed by heat without deforming the substrate.

  A first example of an embodiment of a method for manufacturing a semiconductor device according to the present invention will be described with reference to manufacturing process cross-sectional views schematically shown in FIGS.

As shown in FIG. 1 (1), a mask layer 12 is formed on the substrate 11. For example, the base 11 is formed by forming an insulating film 22 on a silicon substrate 21. The insulating film 22 is, for example, a silicon oxide (SiO ₂ ) film, and has a thickness of, for example, 150 nm.

  The mask layer 12 is formed by applying a resist by, for example, a spin coating method. As this resist, either a positive resist or a negative resist may be used. Here, a positive resist is used as an example. Next, the resist is irradiated with ultraviolet rays by a lithography technique using a mask (not shown) suitable for the electrode structure to be finally produced, and a portion exposed to the ultraviolet rays is removed by a developer to form an electrode. A mask layer 12 having an upper opening is formed.

Next, as shown in FIG. 1B, the surface of the base 11 in the opening of the mask layer 12 is used to improve the adhesion between the underlying insulating film 22 made of silicon oxide and the metal electrode to be formed later. The metal fine particles 13 for improving the adhesion are disposed. The metal fine particles 13 are arranged, for example, by applying a 1 mM concentration solution in which nickel fine particles (for example, about 5 nm in diameter) are dispersed in an organic solvent such as toluene to the substrate surface, rinsing the surface several times with the same organic solvent, Excess nickel fine particles placed on the substrate surface are removed, and the particles are naturally dried until the organic solvent is sufficiently evaporated (1 hour or more). In this way, the adhesion layer 14 is formed. The metal fine particles 13 for improving the adhesion may be fine particles of nickel, chromium, titanium, copper, or alloys thereof. Wherein the metal particles 13 of average particle diameter r _AVE, when the standard deviation of the particle size of the fine metal particles 13 was sigma, it is preferable to satisfy the σ / r _AVE ≦ 0.5. The range of r _AVE is 5.0 × 10 ⁻¹⁰ m ≦ r _AVE ≦ 1.0 × 10 ⁻⁶ m, preferably 5.0 × 10 ⁻¹⁰ m ≦ r _AVE ≦ 1.0 × 10 ⁻⁸ m. It is desirable that

Next, as shown in FIG. 1 (3), using the mask layer 12, the metal fine particles 15 are arranged on the surface of the adhesion layer 14 in the opening to form the metal particle layer 16. The metal fine particles 15 can be metal fine particles such as chromium, titanium, nickel, copper, or fine particles made of an alloy of these metal fine particles. Wherein the metal particles 15 of average particle diameter r _AVE, when the standard deviation of the particle size of the fine metal particles 15 was sigma, it is preferable to satisfy the σ / r _AVE ≦ 0.5. The range of r _AVE is 5.0 × 10 ⁻¹⁰ m ≦ r _AVE ≦ 1.0 × 10 ⁻⁶ m, preferably 5.0 × 10 ⁻¹⁰ m ≦ r _AVE ≦ 1.0 × 10 ⁻⁸ m. It is desirable that

  Specifically, the method of forming the metal fine particle layer 16 is, for example, from gold fine particles (for example, about 5 nm in diameter) as metal fine particles in which the substrate 11 is submerged in water and molecules having amino groups on the water surface are bonded to the surface. A Langmuir film (gold fine particle layer) is formed, and the Langmuir film is transferred to the substrate 11. Then, it is naturally dried until moisture on the substrate 11 is sufficiently evaporated (for example, for 1 hour or more). As a result, the metal fine particles 15 are arranged on the adhesion layer 14 in the opening of the mask layer 12 to form a metal fine particle layer 16 made of gold fine particles. As the metal fine particles, platinum (Pt), silver (Ag), or the like can be used in addition to gold (Au).

  The method for forming the metal fine particle layer 16 includes the above-described transfer of the Langmuir film (single layer film) (single layer film method) or the dropping of a solution in which the metal fine particles are dispersed in an organic solvent onto the substrate. (Drip method) or by immersing the substrate in a solution in which metal fine particles are dispersed in an organic solvent (immersion method).

  Next, as shown in FIG. 2 (4), the adhesion layer 14 and the metal fine particle layer 16 are dissolved to form an electrode 17 made of a metal layer. The electrode 17 is formed, for example, by heating the substrate 11 from the lower surface with a hot plate at a temperature of 120 ° C. for 30 minutes or more to dissolve nickel fine particles and gold fine particles, thereby forming a metal electrode having a thickness of several nm. The metal fine particle layer 16 can be heated and dissolved by, for example, energy beam irradiation such as electron beam irradiation or laser beam irradiation.

  Thereafter, the mask layer 12 made of resist is selectively removed. As this removal method, the resist is removed by a remover. As a result, as shown in FIG. 2 (5), the electrode 17 is formed at the intended position. Further, on the electrode 17 and on the insulating film 22 therebetween, a conductive path 24 composed of a semiconductor molecule layer in which metal fine particles are crosslinked by organic molecules to form a network is formed. In this method of forming a semiconductor molecular layer, for example, one layer of fine particles is formed. Next, an organic semiconductor molecule is brought into contact with the fine particle layer to form a combined layer of the fine particle and the organic semiconductor molecule. Thereby, one combined body layer can be formed. Then, by repeating the above steps, a conductive path 24 composed of a combined body layer having a desired thickness is formed.

  For example, the conductive path invented by the present inventors can be used as a specific method for producing the conductive path 24. This conductive path is, for example, an organic semiconductor molecule such as 4,4′-biphenyldithiol. By means of functional groups at both ends, fine particles made of a conductor such as gold (Au) or semiconductor and the organic semiconductor molecule are alternately bonded, and the conductive path in the fine particle and the conductive path in the organic semiconductor molecule are two-dimensional or tertiary. It is formed by forming a network-type conductive path that is originally connected (see Japanese Patent Application Laid-Open No. 2004-88090).

  In this method for manufacturing a semiconductor device, a metal particle layer 16 is formed on the surface of the substrate 11 in the opening of the mask layer 12 to form a metal particle layer 16, and an electrode 17 made of a metal layer by dissolving the metal particle layer 16. Therefore, it is possible to form the electrode 17 having a film thickness of, for example, nm order, so that a single layer film made of fine particles can be formed on the electrode 17 without causing breakage. Can do.

  Next, a transistor manufacturing method to which the manufacturing method of the first example is applied will be described with reference to the manufacturing process sectional views schematically shown in FIGS.

As shown in FIG. 3A, a mask layer 12 having an opening on a region where an electrode is to be formed is formed on a substrate 11. The base 11 is obtained by forming a gate electrode 32 on a substrate 31 such as a resin substrate, a glass substrate, a quartz substrate, or a ceramic substrate, and further forming a gate insulating film 33 that covers the gate electrode 32. The gate electrode 32 is made of, for example, a conductive material such as gold (Au), platinum (Pt), aluminum (Al), nickel (Ni), titanium (Ti), conductive polymer, or a combination of these conductive materials. It is formed using things. The gate insulating film 33 is, for example, polymethyl methacrylate (PMMA), SOG (Spin on glass), silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), metal oxide high dielectric insulating film, or the like. Or a combination of these.

  The mask layer 12 is formed by applying a resist by, for example, a spin coating method. As this resist, either a positive resist or a negative resist may be used. Here, a positive resist is used as an example. Next, the resist is irradiated with ultraviolet rays by a lithography technique using a mask (not shown) suitable for the electrode structure to be finally produced, and a portion exposed to the ultraviolet rays is removed by a developer to form an electrode. A mask layer 12 having an upper opening is formed.

  Next, as shown in FIG. 3B, the base 11 in the opening of the mask layer 12 is formed in order to improve the adhesion between the gate insulating film 33 made of underlying silicon oxide and the metal electrode to be formed later. Metal fine particles 13 for enhancing adhesion are disposed on the surface. The metal fine particles 13 are arranged, for example, by applying a 1 mM concentration solution in which nickel fine particles (for example, about 5 nm in diameter) are dispersed in an organic solvent such as toluene to the substrate surface, rinsing the surface several times with the same organic solvent, Excessive nickel fine particles placed on the substrate surface were removed, and the particles were naturally dried until the organic solvent was sufficiently evaporated (1 hour or more). In addition to nickel, fine particles of chromium, titanium, or an alloy thereof may be used. Thereby, the adhesion layer 14 is formed.

  Next, as shown in FIG. 3 (3), using the mask layer 12, metal fine particles 15 are arranged on the surface of the adhesion layer 14 in the opening to form a metal particle layer 16. Specifically, as the metal fine particles in which the substrate 11 is submerged in water and molecules having amino groups on the water surface are bonded to the surface, for example, a Langmuir film (gold fine particle layer) made of gold fine particles (for example, a diameter of about 5 nm). ) And the Langmuir film is transferred to the substrate 11. Then, it is naturally dried until moisture on the substrate 11 is sufficiently evaporated (for example, for 1 hour or more). As a result, the metal fine particles 15 are arranged on the adhesion layer 14 in the opening of the mask layer 12 to form a metal fine particle layer 16 made of gold fine particles. As the metal fine particles, platinum (Pt), silver (Ag), or the like can be used in addition to gold (Au).

  Next, as shown in FIG. 4 (4), the adhesion layer 14 and the metal fine particle layer 16 are dissolved to form an electrode (source electrode) 17 (17S) made of a metal layer, and an electrode (drain electrode) made of a metal layer. 17 (17D) is formed. In this electrode formation, for example, the substrate 11 is heated from the lower surface with a hot plate at a temperature of 120 ° C. for 30 minutes or more to dissolve nickel fine particles and gold fine particles, thereby forming the source electrode 17S and drain electrode 17D having a thickness of several nm. Form.

  Thereafter, the mask layer 12 made of resist is selectively removed. As this removal method, the resist is removed by a remover. As a result, as shown in FIG. 4 (5), the source electrode 17S and the drain electrode 17D are formed at the intended positions. Further, a channel layer 34 is formed on the source electrode 17S, the drain electrode 17D, and the gate insulating film 33 therebetween. As a method for forming the channel layer 34, for example, one layer of fine particles is formed. Next, an organic semiconductor molecule is brought into contact with the fine particle layer to form a combined layer of the fine particle and the organic semiconductor molecule. Thereby, one combined body layer can be formed. Then, by repeating the above steps, a channel layer 34 composed of a combined body layer having a desired thickness is formed.

  The specific manufacturing method of the channel layer 34 is the same as the manufacturing method of the semiconductor molecular layer.

  According to the manufacturing method, the source electrode 17S and the drain electrode 17D can be formed by using the electrode having enhanced conductivity. Therefore, the thickness of the source electrode 17S and the drain electrode 17D is thin, for example, 10 nm or more and 25 nm or less. Can be formed. As a result, the channel layer 34 is continuously disconnected without breaking at the contact portion between the channel layer 34 formed of a semiconductor molecule layer in which metal fine particles are crosslinked by organic molecules and networked, and the source electrode 17S and the drain electrode 17D. It can be formed in a close contact state. Therefore, the characteristics of the semiconductor device can be improved.

  Next, a second example of one embodiment of the method for manufacturing a semiconductor device of the present invention will be described with reference to FIG.

As shown in FIG. 5 (1), a paste material in which metal fine particles (for example, gold (Au) fine particles) covered with a protective film made of organic molecules are dispersed by a printing method, a transfer method using a mold, a lithography technique, or the like. The pattern 41 is formed on the substrate 11 by using it. For example, the base 11 is formed by forming an insulating film 22 on a silicon substrate 21. The insulating film 22 is, for example, a silicon oxide (SiO ₂ ) film, and has a thickness of, for example, 150 nm.

  Thereafter, the substrate is immersed in an organic solvent having an action of desorbing organic molecules from the metal fine particles. The organic solvent is removed from the metal fine particles by rinsing the substrate 11 with the organic solvent as necessary several times. For rinsing or the like, the substrate 11 is immersed and rinsed a number of times for a sufficiently long time as necessary until organic molecules are sufficiently removed.

  By removing the organic molecules that enabled the dispersion of the metal fine particles, the metal fine particles can be fused as shown in the photograph of FIG. 5 (2), and thereafter, as shown in FIG. 5 (3). In addition, an electrode 42 having an intended pattern shape is formed, and a conductive layer (or a semiconductor layer) 43 in which metal fine particles are cross-linked by organic molecules to form a network is formed to form a semiconductor device. Moreover, in the said manufacturing method, it becomes possible to perform wiring, without using a vacuum evaporation system, and can produce fine electronics easily. The heat treatment for fusing the metal fine particles can be performed by, for example, energy beam irradiation such as electron beam irradiation or laser beam irradiation.

  In addition, when the adhesion between the surface of the substrate 11 (the surface of the insulating film 22) and the electrode 42 is low, chromium, titanium, nickel covered with a protective film made of organic molecules as a material having good adhesion with the surface of the substrate 11 , Copper, or a fine particle of these alloys is used to form a pattern on the surface of the substrate 11 using a printing method, a transfer method using a mold, a lithography technique, etc., and then the organic molecules are desorbed to be melted. It is preferable to form an adhesion layer for improving the adhesion between the electrode 11 and the electrode 42.

  The second example described with reference to FIG. 5 can be applied to the method for forming the source electrode and the drain electrode in the method for manufacturing the semiconductor device described with reference to FIGS.

  In this method of manufacturing a semiconductor device, a step of forming a paste material pattern 41 in which metal fine particles covered with a protective film made of organic molecules are dispersed on an electrode forming region, and metal molecules are released by desorbing the organic molecules. Since the process includes the step of forming the electrode 42 such as the source electrode and the drain electrode by fusing the fine particles, the conductivity of the electrode 42 can be increased. This makes it possible to form an electrode having a thickness of, for example, nm order, so that a single layer film made of fine particles can be formed on the electrode.

  In both the first and second examples, the same fine particles are used for both electrodes (for example, a source electrode and a drain electrode) and a semiconductor layer (for example, a channel layer) by coating in the transistor manufacturing process. This makes it possible to reduce the complexity in the manufacturing process. In addition, when forming an electrode on a soft plastic substrate or the like that undergoes deformation due to heat, the electrode is formed by removing a protective film made of organic molecules bonded to fine metal particles arranged in advance at an intended location. By doing so, deformation of the substrate can be prevented.

  As described above, the method for manufacturing a semiconductor device of the present invention uses, for example, nano-sized metal fine particles covered with a protective film made of organic molecules, so that a large-scale high vacuum deposition apparatus or the like is not used. Further, there is an advantage that a thin electrode having a nano-scale thickness can be formed. Further, since a high-temperature process is not used, there is an advantage that it is possible to perform electrode formation on a plastic substrate that is likely to be deformed by heat without deforming the substrate.

  In the above description, a bottom gate type semiconductor device has been described as an example. However, the present invention can also be applied to a top gate type semiconductor device. That is, a source electrode and a drain electrode are formed on a substrate having an insulating film formed on the surface by the manufacturing method of the present invention. Next, a channel layer is formed over the source electrode, the drain electrode, and the insulating film between the source electrode and the drain electrode. A gate insulating film may be formed on the channel layer, and a gate electrode may be formed on the gate insulating film at a desired position between the source electrode and the drain electrode.

It is manufacturing process sectional drawing which showed typically the 1st example of one Embodiment which concerns on the manufacturing method of the semiconductor device of this invention. It is manufacturing process sectional drawing which showed typically the 1st example of one Embodiment which concerns on the manufacturing method of the semiconductor device of this invention. It is manufacturing process sectional drawing which showed typically the manufacturing method of the transistor to which the manufacturing method of the 1st example was applied. It is manufacturing process sectional drawing which showed typically the manufacturing method of the transistor to which the manufacturing method of the 1st example was applied. It is manufacturing process sectional drawing and the photograph which showed typically the 2nd example of one Embodiment which concerns on the manufacturing method of the semiconductor device of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Base | substrate, 12 ... Mask layer, 15 ... Metal fine particle, 16 ... Metal fine particle layer, 17 ... Electrode, 24 ... Conductive path

Claims (10)

A method for manufacturing a semiconductor device, comprising: a conductive path formed by fine particles made of a conductor or a semiconductor and organic semiconductor molecules bonded to the fine particles on a substrate; and an electrode connected to the conductive path.
The step of forming the electrode includes:
Forming a mask layer having an opening on a region for forming an electrode on the substrate;
Forming a metal particle layer by disposing metal fine particles on the substrate surface in the opening of the mask layer;
A step of dissolving the metal fine particle layer to form a metal layer. The method for manufacturing a semiconductor device according to claim 1, further comprising a step of forming an adhesion layer on a substrate in the opening before forming the metal fine particle layer. The step of forming the adhesion layer includes
After the step of forming a mask layer having an opening on a region for forming an electrode on the substrate,
Disposing metal fine particles forming an adhesion layer on the surface of the substrate in the opening of the mask layer;
The method for manufacturing a semiconductor device according to claim 2, further comprising: dissolving the metal fine particle layer to form an adhesion layer. Forming the metal fine particle layer;
The method for manufacturing a semiconductor device according to claim 1, wherein the step of dissolving the metal fine particle layer and forming the metal layer is repeated. The method for manufacturing a semiconductor device according to claim 1, wherein the electrodes are a source electrode and a drain electrode of a transistor. A method for manufacturing a semiconductor device, comprising: a conductive path formed by fine particles made of a conductor or a semiconductor and organic semiconductor molecules bonded to the fine particles on a substrate; and an electrode connected to the conductive path.
The step of forming the electrode includes:
Patterning a paste material in which fine metal particles covered with a protective film made of organic molecules are dispersed on the substrate on the electrode forming region;
And a step of fusing metal fine particles to form the electrode by desorbing the organic molecules. The method for manufacturing a semiconductor device according to claim 6, further comprising a step of forming an adhesion layer on a substrate in the opening before forming the metal fine particle layer. The step of forming the adhesion layer includes
Patterning a paste material in which metal fine particles forming an adhesion layer covered with a protective film made of organic molecules on the substrate are dispersed on the electrode forming region;
The method for manufacturing a semiconductor device according to claim 7, further comprising: fusing metal fine particles forming an adhesion layer by desorbing the organic molecules to form the adhesion layer. Patterning a paste material in which fine metal particles covered with a protective film made of organic molecules are dispersed on the substrate on the electrode forming region;
The method of manufacturing a semiconductor device according to claim 6, wherein the step of fusing metal fine particles to form the electrode by desorbing the organic molecules is repeated. The method of manufacturing a semiconductor device according to claim 6, wherein the electrodes are a source electrode and a drain electrode of a transistor.

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