JP2017120349A - Photosensitive resin composition and method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive resin composition that has high-temperature heat resistance and conductivity, eliminates a problem of imparting a metal impurity to a semiconductor substrate, allows pattern formation, and is inexpensive and applicable to a high-temperature ion implantation process, and a method for manufacturing a semiconductor device using the above composition.SOLUTION: The photosensitive resin composition of the present invention comprises a photosensitive resin and particles of a conductive material and/or a semiconductor material. The method for manufacturing a semiconductor device of the present invention includes: a step of forming a film pattern (11) of the photosensitive resin composition of the present invention on a semiconductor layer or a substrate (2); a step of calcining the film pattern of the photosensitive resin composition to form a mask (13) for ion implantation; a step of implanting ions in the semiconductor layer or the substrate (2) through a pattern opening (12) of the mask for ion implantation; and a step of removing the mask (13) for ion implantation.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a photosensitive resin composition, and a semiconductor device manufacturing method using the photosensitive resin composition.

  Most current power semiconductor devices are manufactured using semiconductor Si. In power semiconductor devices using Si, the limit of performance due to the material properties of Si is approaching. When semiconductor SiC is used as a semiconductor material, it has a withstand voltage characteristic, high saturation electron mobility, and high thermal conductivity that greatly exceed that of semiconductor Si, thus improving performance of power semiconductor devices, reducing loss, and device cooling mechanism. Therefore, it is promising as a next-generation power semiconductor material.

  In order to manufacture a SiC power device, it is necessary to implant ions into a desired portion in SiC and dope carriers. In ion doping of SiC, since the diffusion coefficient of SiC dopant is small and it is difficult to apply a thermal diffusion method, a doping method by ion implantation is widely used.

  In the step of reducing the resistance of SiC by ion implantation, high dose ion implantation is required. However, when high-concentration ion implantation is performed at room temperature, SiC becomes amorphous, so that expected device performance cannot be obtained. Further, once amorphous SiC is obtained, it is difficult to restore the polymorphic structure having the same crystallinity as that before ion implantation, even by thermal firing.

  Therefore, by maintaining the substrate at a high temperature of 200 ° C. or higher in the ion implantation process to SiC, the crystallinity of the substrate is restored at the same time as the ion implantation, thereby preventing the deterioration of the electrical characteristics of the device. The law is known.

  In the above high-temperature ion implantation method, since ion implantation is performed at a high temperature of 200 ° C. or higher, a photoresist material used for ion implantation at room temperature such as ion implantation into silicon, for example, chemically amplified photo, is used as an ion implantation mask layer. The resist cannot be used.

Therefore, in the above high-temperature ion implantation method, as an ion implantation mask, an inorganic film such as SiO ₂ having sufficient heat resistance at the substrate temperature in the ion implantation step, for example, chemical vapor deposition (CVD) (Chemical Vapor Transport ( It has been proposed to use an inorganic film such as SiO ₂ deposited by CVD)) (for example, Patent Document 1). By previously patterning such a heat-resistant ion implantation mask on the semiconductor SiC, carrier doping can be performed in a desired region in the semiconductor SiC through the opening of the ion implantation mask.

  For the patterning of such a heat-resistant ion implantation mask, a dry process such as a wet etching method or a reactive ion etching method (RIE) using a photoresist as a mask is used.

  An example of the ion implantation mask forming step and the ion implantation step will be described with reference to FIG.

First, an SiC substrate (2) having an SiC epitaxial film (1) is provided (FIG. 2 (a)), and an SiO ₂ film (3) is deposited on the SiC epitaxial film (1) by a CVD method or the like. (FIG. 2 (b)). Next, a photosensitive resist (4) is formed on the SiO ₂ film (3) (FIG. 2C). Thereafter, patterning exposure and development, which are normal photolithography processes, are performed to form a photosensitive resist pattern (FIG. 2D). Thereafter, the SiO ₂ film is removed by hydrofluoric acid or the like to obtain a desired SiO ₂ film pattern having a mask pattern opening (12) (FIG. 2E). Next, the photosensitive resist is removed by O ₂ ashing (FIG. 2F). Thereafter, ion implantation is performed at a high temperature of 200 ° C. or higher by using a dopant ion beam (7) to form an ion implantation region (6) (FIG. 2 (g)), and hydrofluoric acid or the like is used. The SiO ₂ film is peeled off by a wet process (FIG. 2 (h)).

  Since this ion implantation process has many steps, is complicated, and is a high-cost process, simplification of the process is required.

  In order to simplify the process, a method of performing ion implantation at room temperature using a chemically amplified photoresist as an ion implantation mask has been proposed (for example, Patent Document 2).

As in Patent Documents 1 and 2, when performing high-density ion implantation into a semiconductor covered with an insulator film such as an ion implantation mask, charging (charge-up) generated in the base material and the ion implantation mask is a problem. Become. When the substrate and the ion implantation mask are charged during the ion implantation process, a potential difference occurs between the region in the semiconductor where the ion implantation is performed, the insulator such as the ion implantation mask, and the semiconductor substrate, and a discharge phenomenon may occur. is there. Further, the density of implanted ions may be uneven due to the space electric field generated by charging. For these reasons, it is known that when high-density ion implantation is performed on a semiconductor covered with an insulator film, the performance and yield of the semiconductor device are reduced. This charging phenomenon is particularly remarkable when the semiconductor surface is covered with an insulator film such as SiO ₂ .

  In order to solve the above-mentioned charging problem, a method has been proposed in which a low-energy secondary ion shower having a polarity opposite to that of implanted ions is supplied to the surface of the substrate to neutralize the charging of the substrate (for example, Patent Document 3).

  In addition to the technique using an ion shower, as a technique for solving the above-mentioned charging problem, when performing ion implantation, an insulating ion implantation mask is made of a conductive antistatic film such as a metal film or a doped semiconductor film. A technique using a method of covering in advance has been proposed (for example, Patent Document 4).

  Also, for the purpose of improving the ion implantation mask as an ion blocking layer, a method of using a metal thin film such as titanium or molybdenum having a high density and high ion shielding performance as an ion implantation mask has been proposed (for example, Patent Document 5). ).

  As a method for omitting the process of forming the ion implantation mask layer, a process using a photoresist containing siloxane is known (for example, Patent Document 6).

JP 2006-324585 A JP 2008-108869 A JP-A-6-295700 JP 7-58053 A JP 2007-42803 A International Publication No. 2013/099785

The technique described in Patent Document 1 that uses a SiO ₂ film grown by CVD as an ion implantation mask is excellent in heat resistance and enables ion implantation at a high temperature, but is complicated in patterning the SiO ₂ film. A process is necessary and expensive. Further, as described above, since the SiO ₂ film that is an ion implantation mask does not have conductivity, there is a problem that causes a charging problem in a high-density ion implantation process.

  The method of using a chemically amplified photoresist as an ion implantation mask described in Patent Document 2 is low in cost because the process is simple, but has a problem that a high temperature ion implantation process cannot be applied because of low heat resistance. is there. In addition, as described above, since the chemically amplified photoresist does not have conductivity, there is a problem that causes a charging problem in a high-density ion implantation process.

  The technique for solving the charging problem using an ion shower described in Patent Document 3 has a problem of high cost because it is necessary to install the ion shower device in the semiconductor device manufacturing apparatus. In addition, it is difficult to control the amount of ion shower supplied, and it is difficult to neutralize the charge generated on the surface of the base material without excess and deficiency and completely solve the problem of charging.

  The technique of covering an insulating ion implantation mask with a conductive antistatic film such as a metal film or a doped semiconductor film in advance when performing ion implantation described in Patent Document 4 is performed by patterning a conductive antistatic film. This requires a complicated process and is expensive. Further, when a metal is used as an ion implantation mask or when a metal is used as a conductive film, there is a possibility that the performance and yield of the semiconductor device may be reduced due to the mixing of metal impurities into the semiconductor substrate.

  The method of using a metal thin film such as titanium or molybdenum described in Patent Document 5 as an ion implantation mask has excellent heat resistance and conductivity, so that ion implantation is possible at a high temperature without causing a charging problem. However, in order to pattern a metal thin film such as titanium or molybdenum, a complicated process is required and the cost is high. Further, when a metal is used as an ion implantation mask, there is a possibility that the performance and yield of the semiconductor device are reduced due to the mixing of metal impurities into the semiconductor substrate.

  The method of obtaining a polysiloxane fired product pattern on a base material by patterning the photosensitive resin composition containing polysiloxane on the base material and thermally firing it described in Patent Document 6 is up to 1000 ° C. It is possible to form an ion implantation mask pattern having the above heat resistance on a substrate, but since the polysiloxane fired product does not have electrical conductivity, the problem of charging during ion implantation cannot be solved.

  The present invention has been made in view of the background as described above, has high-temperature heat resistance and conductivity, has no fear of causing metal impurities to the semiconductor substrate, allows pattern formation, and is low. Provided is a photosensitive resin composition that can be applied to a high-temperature ion implantation process at low cost.

  In response to the above problems, the inventors of the present invention have arrived at the present invention described below.

<1> A photosensitive resin composition containing a photosensitive resin and particles of a conductive material and / or a semiconductor material.
<2> The composition according to <1>, wherein the particles are metal, metalloid, or a combination thereof.
<3> The composition according to <2>, wherein the particles are silicon particles.
<4> The composition according to <3>, wherein the silicon particles contain at least one element selected from group 13 and group 15 elements as a dopant.
<5> The composition according to <4>, wherein the silicon particles contain boron or phosphorus as a dopant.
<6> The composition according to <4> or <5>, wherein the concentration of the dopant in the silicon particles is 10 ¹⁸ atoms / cm ³ or more.
<7> The composition according to any one of <3> to <6>, wherein the metal impurity content is 100 ppb or less for each metal element.
<8> The composition according to any one of <1> to <7>, wherein the average particle diameter of the particles is 1 to 500 nm.
<9> The composition according to <8>, wherein the particles have an average particle size of 1 to 100 nm.
<10> When the film of the photosensitive resin composition is baked at 800 ° C. for 1 hour in the air to obtain a mask layer having a thickness of 0.5 μm, the sheet resistance of the mask layer is 10 ^12. The composition according to any one of <1> to <9>, which is Ω / □ or less.
<11> The composition according to any one of <1> to <10>, further containing a siloxane compound.
<12> forming a film pattern of the photosensitive resin composition according to any one of <1> to <11> above on a semiconductor layer or a substrate;
Baking the pattern of the film of the photosensitive resin composition to form a mask for ion implantation;
A step of implanting ions into the semiconductor layer or substrate through a pattern opening of the ion implantation mask;
A method for manufacturing a semiconductor device, comprising a step of removing the ion implantation mask.
<13> The photosensitive resin composition film according to any one of the items <1> to <11>, wherein the step of forming a pattern of the photosensitive resin composition film on the semiconductor layer or the substrate is performed. Is formed on a semiconductor substrate, and is subjected to patterning exposure and development on the film of the photosensitive resin composition.
<14> The method according to <12> or <13> above, wherein the semiconductor layer or the substrate is a SiC layer or a substrate.
<15> The method according to any one of <12> to <14> above, wherein the temperature of the semiconductor layer or the substrate in the ion implantation step is 200 ° C. or higher.

  According to the photosensitive resin composition of the present invention, the process can be saved in the high-temperature ion implantation process as compared with the conventional process, and a low-cost manufacturing process can be provided. In addition, according to the photosensitive resin composition of the present invention, an antistatic device or an antistatic process on a semiconductor device, which has been necessary for antistatic in the conventional ion implantation process, can be omitted. Process can be provided. Therefore, according to the manufacturing method of the present invention, it is possible to provide a low-cost power semiconductor manufacturing process with higher productivity and yield than the conventional method.

FIG. 1 is a schematic diagram of an ion implantation process in the present invention. FIG. 2 is a schematic view of a conventional ion implantation process. FIG. 3 is a diagram showing the Al concentration distribution in the depth direction obtained by SIMS measurement in FIG.

<< Photoreceptor resin composition >>
The photoreceptor resin composition of the present invention contains a photosensitive resin and particles of a conductive material and / or a semiconductor material.

  As the photosensitive resin used in the photosensitive resin composition of the present invention, those having negative or positive photosensitivity can be arbitrarily selected, and in particular, the photosensitive resin used in the formation of an ion implantation mask. Can be used. The photosensitive resin composition of this invention can be used in order to obtain the mask used in an ion implantation process.

<Particles of conductive material and / or semiconductor material>
The conductive material and / or the semiconductor material constituting the particles used in the present invention are formed by forming a mask for ion implantation using the photosensitive resin composition of the present invention, and when performing ion implantation, the semiconductor layer or The mask can be selected such that the mask has sufficient conductivity to suppress charging (charge-up) that occurs in the substrate and the ion implantation mask.

  As the particles used in the present invention, a single type of particle may be used, or two or more types of particles may be used in combination.

Specifically, as the conductive material and / or semiconductor material, for example, 1 × 10 ¹² Ωm or less, 1 × 10 ⁹ Ωm or less, 1 × 10 ⁶ Ωm or less, 1 × 10 ³ Ωm or less, 1 × 10 ³ Ωm or less, 1 Ωm or less, 1 A material having a resistivity of × 10 ⁻³ Ωm or less or 1 × 10 ⁻⁶ Ωm or less can be selected.

Among these, from the viewpoint of preventing charging even in a high-throughput ion implantation process performed at a high beam density of 100 mA class, this conductive material and / or semiconductor material is preferably 1 × 10 ³ Ωm or less, more preferably A material having a resistivity of preferably 1 Ωm or less, more preferably 1 × 10 ⁻³ Ωm or less, and particularly preferably 1 × 10 ⁻⁶ Ωm or less can be selected.

Further, the conductive material and / or the semiconductor material can be obtained when the photosensitive resin composition film is baked at 800 ° C. for 1 hour in the atmosphere to obtain a mask layer having a thickness of 0.5 μm. The sheet resistance of the layer can also be selected to be 10 ¹² Ω / □ or less, 10 ¹¹ Ω / □ or less, or 10 ¹⁰ Ω / □ or less.

  From the viewpoint of stabilizing the pattern shape in the ion implantation step, the particles used in the present invention are preferably particles of a material having a melting point exceeding the temperature of the semiconductor layer or the substrate in the ion implantation step.

  Therefore, for example, as particles used in the present invention, particles of a material having a melting point of, for example, 400 ° C. or higher, 600 ° C. or higher, 800 ° C. or higher, 1000 ° C. or higher, 1200 ° C. or higher, and 1500 ° C. or higher can be used.

  The average primary particle size of the particles used in the present invention can be 500 nm or less, 200 nm or less, 100 nm or less, 50 nm or less, 20 nm or less, or 5 nm or less. The average primary particle size of the particles used in the present invention can be 1 nm or more.

  The average primary particle size of the particles used in the present invention is set to 200 nm or less, 100 nm or less, 50 nm or less, 20 nm or less, or 5 nm or less in order to suppress light scattering during patterning exposure and reduce pattern bleeding. It is preferable.

  Here, in the present invention, the average primary particle diameter of the particles is a projected area circle equivalent diameter directly based on a photographed image by observation with a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like. The number average primary particle diameter can be obtained by measuring and analyzing a particle group consisting of 100 or more aggregates.

  As the particles used in the present invention, particles of metal, metalloid, or a combination thereof may be used. Here, examples of the semimetal include silicon and germanium.

  In the step of performing ion implantation by heating the semiconductor layer or the substrate to a high temperature, in order to prevent contamination of the semiconductor layer or the substrate by metal impurities, particles of the semiconductor material, particularly particles of the same semiconductor material as the semiconductor layer or the substrate are added. It is preferable to use it.

  Thus, for example, the particles used in the present invention are silicon (Si), germanium (Ge), diamond (C), silicon carbide (SiC), silicon germanium (SiGe), gallium nitride (GaN), indium phosphide (InP). , Particles of a semiconductor material such as gallium arsenide (GaAs), cadmium sulfide (CdS), zinc selenide (ZnSe), or zinc oxide (ZnO).

  The particles of semiconductor material, in particular silicon particles, may be pre-doped with impurity dopants and thereby have favorable conductivity.

  In this case, the particles of the semiconductor material, particularly silicon particles, may contain at least one element of Group 13 and Group 15 elements as a dopant. That is, the dopant may be p-type or n-type. For example, boron (B), aluminum (Al), gallium (Ga), indium (In), titanium (Ti), iron (Fe), The dopant may contain a dopant selected from the group consisting of phosphorus (P), arsenic (As), antimony (Sb), or combinations thereof, such as boron or phosphorus.

  In particular, when silicon particles contain boron as a dopant, boron provides preferable conductivity to silicon particles, while boron is difficult to move from silicon particles to a semiconductor substrate in an ion implantation process. preferable.

The concentration of the dopant in the semiconductor particles, particularly silicon particles, may be 10 ¹⁸ atoms / cm ³ or more, 10 ¹⁹ atoms / cm ³ or more, or 10 ²⁰ atoms / cm ³ or more.

  In the step of performing ion implantation by heating the semiconductor layer or the substrate to a high temperature, the concentration of the metal impurity contained in the semiconductor particles is 100 ppb for each metal element in order to prevent the semiconductor layer or the substrate from being contaminated by metal impurities. Hereinafter, semiconductor particles of 50 ppb or less, 20 ppb, or 10 ppb or less can be used. Here, when the semiconductor is a compound semiconductor containing a metal as a constituent element, the “metal impurity” means a metal other than the metal constituting the semiconductor.

  The particles used in the present invention can be used at any concentration as long as an ion implantation mask can be formed. For example, the particles used in the present invention are preferably used in a proportion of 1% by weight to 90% by weight with respect to the photosensitive resin composition. By setting the concentration of the particles to 90% by weight or less, the photosensitive resin composition film can be patterned without a significant decrease in the photosensitivity of the photosensitive resin composition. Further, by setting the concentration of the conductive particles to 1% by weight or more, an ion implantation mask having a film thickness sufficient to exhibit performance as an ion implantation mask layer is obtained by baking the photosensitive resin composition film. Can be formed.

<solvent>
The photosensitive resin composition of the present invention may further contain a solvent. Although there is no restriction | limiting in particular in the kind of solvent, It is preferable to select the solvent which can dissolve the component contained in the photosensitive resin composition and can disperse | distribute the particle | grains used by this invention uniformly.

  The boiling point under atmospheric pressure of the solvent contained in the photosensitive resin composition of the present invention is preferably 110 ° C to 250 ° C. By selecting a solvent having a boiling point of 110 ° C. or higher, the solvent evaporates at an appropriate rate when the photosensitive resin composition film is formed, and a uniform film is obtained. In addition, by selecting a solvent having a boiling point of 250 ° C. or less, it is possible to reduce the amount of solvent remaining in the photosensitive resin composition film after the formation of the photosensitive resin composition film. It is possible to suppress cracks and surface flatness due to the above.

<Binder>
The photosensitive resin composition of the present invention may contain a binder for the purpose of binding particles in the baking step of the photosensitive resin composition to form a stable ion implantation mask. Examples of the binder used in the photosensitive resin composition of the present invention include a polysiloxane compound.

<< Semiconductor Device Manufacturing Method >>
The inventive method for manufacturing a semiconductor device comprises the following steps:
Forming a film pattern of the photosensitive resin composition of the present invention on a semiconductor layer or substrate;
Baking the pattern of the film of the photosensitive resin composition to form a mask for ion implantation;
A step of implanting ions into the semiconductor layer or the substrate through a pattern opening of the mask for ion implantation, and a step of removing the mask for ion implantation.

  Here, the step of forming the pattern of the photosensitive resin composition film on the semiconductor layer or the substrate includes forming the photosensitive resin composition film of the present invention on the semiconductor substrate, and this photosensitive resin composition. Patterning exposure and development may be included on the object film.

  An example of the method of the present invention for manufacturing a semiconductor device is described below with reference to FIG.

  First, as shown in FIG. 1 (a), an SiC substrate (2) having an SiC epitaxial film (1) is provided, and as shown in FIG. 1 (b), a photosensitive resin composition film (11) is provided. ) Is formed on the SiC substrate by any method.

  Then, patterning exposure is performed by patterning exposure of the photosensitive resin composition having light or the like having sensitivity to the photosensitive resin composition film, and immersing the SiC substrate having the photosensitive resin composition film in a developer. The soluble part in the film | membrane of the photosensitive resin composition which passed through the process is removed. According to this, as shown in FIG.1 (c), the pattern of the film | membrane of the photosensitive resin composition which has a mask pattern opening part (12) is formed on a SiC base material (2).

  Thereafter, as shown in FIG. 1 (d), the SiC base material on which the film of the photosensitive resin composition is formed is baked at a temperature at which the organic component contained in the photosensitive resin composition is decomposed, whereby ion implantation is performed. A mask (13) can be obtained.

  Thereafter, as shown in FIG. 1 (e), an ion implantation apparatus is used to pass through the mask pattern opening (12) of the ion implantation mask (13) with the beam (7) of dopant ions of the SiC substrate (2). By performing ion implantation on the surface, an ion implantation region (6) is formed. At this time, the ion implantation process can be performed by heating the semiconductor layer or the substrate to be ion-implanted to a temperature of 200 ° C. or higher.

  Thereafter, as shown in FIG. 1 (f), the ion implantation mask (13) can be removed by means such as immersion in a dissolvable chemical solution.

<Semiconductor layer or substrate>
As the semiconductor layer or substrate, any semiconductor layer or substrate intended to diffuse the dopant can be used.

  Therefore, as a semiconductor layer or substrate, silicon (Si), germanium (Ge), diamond (C), silicon carbide (SiC), silicon germanium (SiGe), gallium nitride (GaN), indium phosphide (InP), Examples include, but are not limited to, gallium arsenide (GaAs), cadmium sulfide (CdS), zinc selenide (ZnSe), zinc oxide (ZnO), and particularly silicon carbide (SiC).

  Moreover, the semiconductor layer or the substrate may be composed of a single layer or a laminate composed of two or more types of layers including one or more semiconductor layers. Such a laminate is a semiconductor laminate having an epitaxial film such as an SiC epitaxial film grown on a semiconductor single crystal substrate such as an SiC single crystal substrate for the purpose of obtaining desired semiconductor device characteristics. It may be.

The semiconductor layer or substrate may be a semiconductor layer or substrate having an impurity dopant of 10 ¹⁶ atoms / cm ³ or less, and may be pre-doped to a concentration exceeding 10 ¹⁶ atoms / cm ³ with an impurity dopant.

  A metal film or a metal wiring pattern may be formed in advance on the semiconductor layer or the substrate.

<Process for forming pattern of photosensitive resin composition film>
In the method of the present invention for producing a semiconductor device, a film pattern of the photosensitive resin composition of the present invention is formed on a semiconductor layer or a substrate.

  This step can include forming a film of the photosensitive resin composition of the present invention on a semiconductor substrate, and patterning exposure and development on the film of the photosensitive resin composition.

  The film of the photosensitive resin composition of the present invention can be formed on the semiconductor substrate by any means capable of forming the film of the photosensitive resin composition on the semiconductor layer or the substrate. . Examples of such means include a spin coating method, a slit coating method, a spray coating method, or a laminating method in which a photosensitive resin composition film prepared on another substrate in advance is transferred onto a semiconductor substrate. However, any method that is not limited to these can be selected.

  When the photosensitive resin composition contains a solvent, it can be baked and the solvent removed after formation of the film of the photosensitive resin composition. As a method for removing the solvent by heating, a method capable of arbitrary heating such as an oven, a hot plate, and infrared rays can be used.

(Thickness of photosensitive resin composition film)
Arbitrary thickness can be selected as the film thickness of the photosensitive resin composition film. The film thickness varies depending on the composition of the photosensitive resin composition, the coating conditions, the coating method, and the like. For example, the coating can be performed so that the film thickness of the photosensitive resin composition is 0.1 μm to 100 μm.

  From the viewpoint of performing baking after patterning the film of the photosensitive resin composition and using it as a mask layer for ion implantation, it is preferable that the film thickness is sufficient for the mask layer for ion implantation. Therefore, for example, in consideration of factors that affect the ion implantation penetration depth, such as the temperature of the semiconductor substrate, the ion acceleration voltage, and the dopant ion species during ion implantation, the resulting ion implantation mask has sufficient ions. The film thickness of the photosensitive resin composition film can be selected so that the film thickness has a stopping power.

(Patterning exposure)
The photosensitive resin composition film can be subjected to patterning exposure by any method suitable for the resist.

  The exposure is to irradiate the photosensitive resin composition with active actinic radiation having photosensitivity, and examples thereof include irradiation with visible light, ultraviolet rays, electron beams, and X-rays. From the viewpoint of being a commonly used light source, for example, it is preferable to use an ultra-high pressure mercury lamp light source capable of irradiating visible light or ultraviolet light. J-line (wavelength 313 nm), i-line (wavelength 365 nm) H-line (wavelength 405 nm) or g-line (wavelength 436 nm).

  Next, if necessary, the following pre-development baking may be performed. By performing pre-development baking, it is possible to expect effects such as improvement in resolution during development and increase in the allowable range of development conditions. As baking temperature in this case, 50-180 degreeC is preferable and 60-150 degreeC is more preferable. The baking time is preferably 10 seconds to several hours. Within the above range, there are advantages that the reaction proceeds satisfactorily and the development time can be shortened.

(developing)
Next, the pattern of the photosensitive resin composition can be obtained by development after patterning exposure. For example, when a film of a photosensitive resin composition after patterning exposure is immersed in a developing solution, if the photosensitive resin composition has negative photosensitivity, the non-exposed portion is removed, and the photosensitive resin composition In the case of having positive-type photosensitivity, the exposed portion is removed, and the film of the photosensitive resin composition can be patterned.

  As the developer, any developer can be selected according to the composition of the photosensitive resin composition. A developer exhibiting alkaline liquidity can be preferably used. For example, tetramethylammonium hydroxide, potassium hydroxide, and sodium hydroxide can be preferably used.

  From an environmental viewpoint, it is desirable to develop with an alkaline aqueous solution rather than an organic alkaline developer.

  Further, the developer may contain a solvent in order to improve the dissolution of the patterning site and the dispersibility of the conductive particles. As examples of the solvent at this time, isopropyl alcohol, acetone, propylene glycol 1-monomethyl ether 2-acetate and the like can be preferably used.

  Further, the developer may contain a surfactant in order to improve the dissolution of the patterning site and the dispersibility of the conductive particles.

  In the development process, the above-described developer is directly applied to the exposed film, the developer is sprayed and emitted, the exposed film is immersed in the developer, and the exposed film is exposed. It can be performed by a method such as applying ultrasonic waves while being immersed in the developer.

  After the development processing, it is preferable to wash the relief pattern formed by development with a rinse solution. As the rinse solution, water can be preferably used when an alkaline aqueous solution is used as the developer. Further, rinsing may be performed by adding alcohols such as ethanol and isopropyl alcohol, esters such as propylene glycol monomethyl ether acetate, acids such as carbon dioxide, hydrochloric acid, and acetic acid to water.

  When rinsing with an organic solvent, methanol, ethanol, isopropyl alcohol, ethyl lactate, ethyl pyruvate, propylene glycol monomethyl ether acetate, methyl-3-methoxypropionate, ethyl-3- Ethoxypropionate, 2-heptanone, ethyl acetate and the like are preferably used.

  When the photosensitive resin composition has positive photosensitivity, bleaching exposure may be performed without using a mask, if necessary. By performing bleaching exposure, effects such as improvement in resolution after baking, control of the pattern shape after baking, and improvement in transparency after baking can be expected. Active actinic rays used for bleaching exposure include ultraviolet rays, visible rays, electron beams, X-rays, etc. In the present invention, mercury lamp j-ray (wavelength 313 nm), i-ray (wavelength 365 nm), h-ray (wavelength) 405 nm) or g-line (wavelength 436 nm) is preferably used.

  Next, middle baking may be performed as necessary. By performing middle baking, effects such as improvement in resolution after baking and control of the pattern shape after baking can be expected. As baking temperature in this case, 60-250 degreeC is preferable and 70-220 degreeC is more preferable. The baking time is preferably 10 seconds to several hours.

<Ion implantation mask formation process>
Next, in the method of the present invention, the pattern of the film of the photosensitive resin composition is baked to form an ion implantation mask.

  This can be done by heating the developed film at a temperature of 200-1000 ° C. This heat treatment can be performed in an air atmosphere or an inert gas atmosphere such as nitrogen. In addition, it is preferable that this heat treatment be performed stepwise or continuously, and performed for 5 minutes to 5 hours. For example, heat treatment is performed at 130 ° C., 200 ° C., and 350 ° C. for 30 minutes each, or the temperature is increased linearly from room temperature to 400 ° C. over 2 hours.

<Ion implantation process>
Next, in the method of the present invention, ions are implanted into the semiconductor layer or the substrate through the pattern opening of the ion implantation mask.

  The mask for ion implantation is preferably applied to a semiconductor device manufacturing process including ion implantation into a SiC layer or a substrate having an ion implantation temperature of 200 to 1000 ° C. The ion implantation temperature is preferably 200 to 1000 ° C, more preferably 200 to 800 ° C, and further preferably 250 to 700 ° C.

  When the semiconductor layer or base material is a SiC layer or base material, if the ion implantation temperature is lower than 200 ° C., the injection layer becomes a continuous amorphous state, and good recrystallization proceeds even if high-temperature annealing is performed. Therefore, there is a concern that a low resistance layer cannot be formed. In this case, if the ion implantation temperature is higher than 1000 ° C., thermal oxidation or step bunching of SiC occurs, and it is necessary to remove those portions after ion implantation.

  When the photosensitive resin composition of the present invention is applied to an ion implantation mask, the resolution is preferably 7 μm or less, more preferably 5 μm or less, and further preferably 3 μm or less.

<Ion implantation mask removal process>
The ion implantation mask is removed after the ion implantation process. Examples of the removal method include, but are not limited to, a wet process using hydrofluoric acid, buffered hydrofluoric acid, hydrofluoric acid, or TMAH, a dry process such as plasma treatment, and the like. A wet process is preferable from the viewpoint of low cost.

<< Examples 1-2 and Comparative Examples 1-3 >>
In the following Examples 1-2 and Comparative Examples 1-3, after preparing a photosensitive resin composition and forming a coating film on a SiC substrate, patterning exposure of ultraviolet light, development, and baking are performed, thereby The resulting ion implantation mask was patterned. In addition, these Examples and Comparative Examples were evaluated for the possibility of patterning, the presence or absence of a pattern after thermal baking, and the presence or absence of problems due to charging during ion implantation.

<Example 1>
(Preparation of boron (B) doped silicon particles)
Silicon nanoparticles were produced by a laser pyrolysis (LP) method using a carbon dioxide laser using monosilane gas as a raw material. At this time, diborane (B ₂ H ₆ ) gas was introduced together with monosilane gas to obtain boron-doped silicon particles. The particle diameter of this particle was 20 nm.

The doping concentration of the obtained boron-doped silicon particles was 1 × 10 ²¹ atoms / cm ³ . Moreover, when the metal impurity content of the obtained boron-doped silicon particles was measured with an inductively coupled plasma mass spectrometer (ICP-MS), the Fe content was 15 ppb, the Cu content was 18 ppb, and the Ni content was 10 ppb, the Cr content was 21 ppb, the Co content was 13 ppb, the Na content was 20 ppb, and the Ca content was 10 ppb.

(Preparation of boron-doped silicon particle-containing solution)
A boron-doped silicon particle-containing solution was prepared by mixing 95% by weight of isopropyl alcohol and 5% by weight of silicon nanoparticles prepared by the above method.

(Preparation of photosensitive resin composition containing silicon nanoparticles and negative photosensitive resin)
A negative photoresist (CTP-100T, manufactured by Merck & Co., Inc.) and the boron-doped silicon particle-containing solution were mixed to prepare a photosensitive resin composition containing silicon nanoparticles and a negative photosensitive resin. At this time, a photosensitive resin composition was prepared so that boron-doped silicon nanoparticles accounted for 20% by weight of the solid content of the photosensitive resin composition after mixing.

(Formation of photosensitive resin composition film)
On the SiC base material, the photosensitive resin composition containing the silicon nanoparticles and the negative photosensitive resin is spin-coated at a rotation speed such that the film thickness is about 2 μm, and is heated on a hot plate at 100 ° C. to 90 ° C. By drying for 2 seconds, a photosensitive resin composition film was obtained.

(Patterning)
The photosensitive resin composition film was exposed to patterning by irradiating ultraviolet light through a photomask pattern using a patterning exposure machine. Patterning exposure was performed using a photomask having a 10 μm line and space as a photomask. The photosensitive resin composition film after patterning exposure was heated on a hot plate at 100 ° C. for 90 seconds, and then immersed in a developing solution (manufactured by Merck & Co., AZ-300MIF) for 60 seconds to perform pattern development. After the development, the substrate with the photosensitive resin composition film was washed with flowing pure water, and then the substrate was dried to form a pattern of the photosensitive resin composition film on the SiC substrate.

(Observation with an optical microscope)
The photosensitive resin composition film after forming the pattern was observed using an optical microscope, and whether or not a 10 μm line and space pattern could be formed was confirmed.

(Baking)
The pattern of the photosensitive resin composition film was baked at 800 ° C. for 1 hour in the atmosphere in an oven to form an ion implantation mask on the SiC substrate. The film thickness of the mask layer for ion implantation after baking was 0.5 μm.

(Observation with an optical microscope)
The presence or absence of the pattern formation in the mask for ion implantation after baking was confirmed using the optical microscope.

(Ion implantation)
Ions were implanted into the SiC substrate through the mask pattern opening of the fired ion implantation mask under the following conditions:
Ion species: Al,
Energy amount: 40 keV,
Injection temperature: 400 ° C
Dose amount: 1 × 10 ¹⁴ Ions / cm ²

  After the Al ion implantation, the ion implantation mask was removed by immersing the substrate in a mixed solution of buffered hydrofluoric acid and concentrated sulfuric acid. Then, the depth dependence from the SiC base material surface of Al concentration was measured using the secondary ion mass spectrometry (SIMS) apparatus.

  In the SIMS measurement, the SiC base material in the region that was the opening of the ion implantation mask at the time of Al ion implantation and the region that was covered by the mask layer for ion implantation at the time of Al ion implantation was used. Performed on the surface. FIG. 3 shows the Al concentration distribution in the depth direction obtained by SIMS measurement.

As shown in FIG. 3, in the Al concentration distribution (21) in the region which was the opening of the ion implantation mask at the time of Al ion implantation, a peak of 1.5 × 10 ¹⁹ atoms / cm ³ is observed at a depth of about 50 nm. A profile with was observed. On the other hand, no significant Al ions were detected in the Al concentration distribution (22) in the region covered with the ion implantation mask layer at the time of Al ion implantation. In the depth dependence measurement of the Al concentration in the region covered with the ion implantation mask layer at the time of Al ion implantation (22), 10 ¹⁴ to 10 ¹⁷ atoms / cm ³ detected in the vicinity of 100 nm from the surface. The Al ions are due to the influence of the surface adsorbate in the SIMS measurement and do not reflect the Al ions implanted into the SiC.

  According to the above SIMS measurement results, Al ions are implanted into the surface of the SiC base material in the region that was the opening of the ion implantation mask at the time of Al ion implantation. Al ions are not implanted into the surface of the SiC base material in the region covered by the mask, and the mask layer for ion implantation in this example has an effect of shielding the implanted ions during ion implantation. Understood.

<Example 2>
As a photosensitive resin composition, instead of mixing a negative photoresist (CTP-100T, manufactured by Merck) and the boron-doped silicon particle-containing solution, a negative photoresist (CTP-100T, manufactured by Merck), the boron A mask layer was formed on the SiC substrate in the same manner as in Example 1 except that the doped silicon particle-containing solution and spin-on glass (12000-T, manufactured by Tokyo Ohka Kogyo Co., Ltd.) were mixed. At this time, of the solid content of the photosensitive resin composition after mixing, the photosensitive resin composition is such that 10% by weight is occupied by boron-doped silicon nanoparticles and 10% by weight is solid content contained in the spin-on-glass solution. A product was prepared.

<Comparative example 1>
As a photosensitive resin composition, instead of mixing a negative photoresist (CTP-100T, manufactured by Merck) and the boron-doped silicon particle-containing solution, a negative photoresist (CTP-100T, manufactured by Merck), SiO ₂ A mask layer was formed on the SiC substrate in the same manner as in Example 1 except that the nanoparticle dispersion solution SIRPMA30WT% -E9 (manufactured by CIK Nanotech Co., Ltd.) was mixed. In this case, among the solid content of the photosensitive resin composition after mixing, as occupied by a 20 wt% solids contained in the SiO ₂ nanoparticle dispersion solution SIRPMA30WT% -E9, to prepare a photosensitive resin composition.

<Comparative example 2>
As a photosensitive resin composition, instead of mixing a negative photoresist (CTP-100T, manufactured by Merck) and the boron-doped silicon particle-containing solution, a negative photoresist (CTP-100T, manufactured by Merck), spin-on glass A mask layer was formed on the SiC substrate in the same manner as in Example 1 except that (12000-T, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was mixed. Under the present circumstances, the photosensitive resin composition was prepared so that solid content contained in spin-on glass might occupy 20 weight% among solid content of the photosensitive resin composition after mixing.

<Comparative Example 3>
As a photosensitive resin composition, instead of using a negative photoresist (CTP-100T, manufactured by Merck) and a solution obtained by mixing the boron-doped silicon particle-containing solution, a negative photoresist (CTP-100T, manufactured by Merck) A step of forming a mask layer on the SiC substrate was carried out in the same manner as in Example 1 except that was used.

  The experimental conditions and results for Examples 1-2 and Comparative Examples 1-3 are summarized in Table 1 below.

<Evaluation results>
From the results of Examples 1 and 2 and Comparative Examples 1 to 3, when silicon (Si) particles were used as the additive, the conductive residue was obtained by thermal firing after patterning of the photosensitive resin composition. While the pattern was able to be formed on the substrate, when conductive non-conductive silica (SiO ₂ ) particles and spin-on glass were added, the conductive residue pattern was formed on the substrate. It is understood that it could not be formed.

  Moreover, from the result of Examples 1-2, in addition to the silicon nanoparticle which has electroconductivity as an additive, also by mixing the spin-on glass which is a binder, by the heat baking after the patterning of the photosensitive resin composition It is understood that a conductive residue pattern could be formed on the substrate.

<< Example 3 and Comparative Example 4 >>
In Example 3 and Comparative Example 4 below, a photosensitive resin composition was prepared, a coating film was formed on a substrate with a thermal silicon oxide film of 1000 nm, and thereafter patterning exposure to ultraviolet light, development, and baking were performed. Then, the mask layer was patterned. In these examples and comparative examples, the sheet resistance of the mask layer was measured.

<Example 3>
Instead of using the SiC substrate as the substrate, a silicon wafer with a thermally oxidized silicon film of 1000 nm was used, and except that the entire surface of the substrate was exposed to ultraviolet light during patterning exposure, the same as in Example 1, Pattern formation of the mask layer was performed. After pattern formation of the mask layer, an aluminum electrode for the purpose of measuring the resistivity of the mask layer pattern was formed on the mask layer pattern using a vacuum evaporation method through a shadow mask.

  As an aluminum electrode pattern for the purpose of resistivity measurement, an electrode pattern in which 1000 μm sides of a pair of rectangular electrodes having a size of 1000 μm × 200 μm are opposed to each other at an interval of 200 μm is used. It was.

  Then, when the sheet resistance of the mask layer was determined by measuring the potential drop between the aluminum electrodes when a constant current of 1 μA was applied between the deposited aluminum electrodes, it was 90 GΩ / □.

<Comparative example 4>
A mask for ion implantation having a pattern was formed on a silicon substrate in the same manner as in Example 3 except that spin-on glass (12000-T, manufactured by Tokyo Ohka) was used instead of the boron-doped silicon particle-containing solution. Later, the sheet resistance of the ion implantation mask was measured. According to this, a current exceeding the measurement limit of the apparatus was not measured, and the sheet resistance of the mask layer was estimated to be 2.0 × 10 ⁸ GΩ / □ or more.

1 SiC epitaxial film 2 SiC substrate 3 SiO ₂ film 4 photosensitive resist 6 ion implantation region 7 dopant ions of the beam 11 the photosensitive resin composition film 12 mask pattern openings 13 mask layer pattern 21 Al ion implantation mask for ion implantation at Al concentration distribution in the region which was the opening of the layer 22 Al concentration distribution in the region covered with the mask layer for ion implantation at the time of Al ion implantation

Claims (15)

  A photosensitive resin composition containing a photosensitive resin and particles of a conductive material and / or a semiconductor material.   The composition of claim 1, wherein the particles are metal, metalloid, or a combination thereof.   The composition according to claim 2, wherein the particles are silicon particles.   The composition according to claim 3, wherein the silicon particles contain at least one element selected from group 13 and group 15 elements as a dopant.   The composition according to claim 4, wherein the silicon particles contain boron or phosphorus as a dopant. The composition of Claim 4 or 5 whose density | concentration of the said dopant in the said silicon particle is 10 < ¹⁸ > atoms / cm < ³ > or more.   The composition according to any one of claims 3 to 6, wherein the metal impurity content is 100 ppb or less for each metal element.   The composition as described in any one of Claims 1-7 whose average particle diameter of the said particle | grain is 1-500 nm.   The composition according to claim 8, wherein the average particle diameter of the particles is 1 to 100 nm. When the film of the photosensitive resin composition was baked at 800 ° C. for 1 hour in the air to obtain a mask layer having a thickness of 0.5 μm, the sheet resistance of the mask layer was 10 ¹² Ω / □. The composition as described in any one of Claims 1-9 which is the following.   The composition according to any one of claims 1 to 10, further comprising a siloxane compound. A step of forming a film pattern of the photosensitive resin composition according to any one of claims 1 to 11 on a semiconductor layer or a substrate,
Baking the pattern of the film of the photosensitive resin composition to form a mask for ion implantation;
A step of implanting ions into the semiconductor layer or substrate through a pattern opening of the ion implantation mask;
A method for manufacturing a semiconductor device, comprising a step of removing the ion implantation mask.   The process of forming the pattern of the film of the said photosensitive resin composition on a semiconductor layer or a base material forms the film | membrane of the photosensitive resin composition as described in any one of Claims 1-11 on a semiconductor base material. And patterning exposure and development to the film of the photosensitive resin composition.   The method according to claim 12 or 13, wherein the semiconductor layer or substrate is a SiC layer or substrate.   The method as described in any one of Claims 12-14 whose temperature of the said semiconductor layer or base material in an ion implantation process is 200 degreeC or more.

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