JP4736032B2 - Ion plating target for manufacturing zinc oxide-based conductive film and its manufacturing method, and manufacturing method of zinc oxide-based conductive film - Google Patents

Description

  The present invention relates to a target used when a zinc oxide-based conductive film is manufactured by an ion plating method, a method for manufacturing the target, and a method for manufacturing a zinc oxide-based conductive film, and in particular, a zinc oxide-based conductive film by an ion plating method. The present invention relates to an improved technique for obtaining a homogeneous and high-performance conductive film free from pinhole defects by preventing or suppressing a splash phenomenon that occurs during heating of a target that is an evaporation material.

  In recent years, the performance improvement of zinc oxide-based conductive films has progressed remarkably, and the specific resistance value, which is one of the main characteristics, is comparable to ITO (indium tin oxide) films at the laboratory level. Low values are starting to be obtained. Therefore, in recent years, when there is concern about the depletion of indium resources, there is an increasing expectation for a zinc oxide-based conductive film as a next-generation conductive film that replaces an ITO film containing expensive indium as an essential component.

  A direct current magnetron sputtering method is known as a representative method for producing a zinc oxide-based conductive film at a mass production level, and this method is excellent in terms of film formation speed and film formation area. However, when a zinc oxide-based conductive film is formed by sputtering, a large resistivity distribution (increase in resistivity at the erosion facing portion) may occur on the substrate.

  On the other hand, the ion plating method described in Patent Documents 1 and 2 irradiates a plasma beam or an electron beam onto an evaporation material (target) with a plasma gun or an electron gun, evaporates the target and ionizes it. This is a method of vapor deposition on a substrate, which does not produce a large resistivity distribution, can produce a zinc oxide-based conductive film with a small specific resistance at a high film-forming speed, and can cope with a large film-forming area. It has the following advantages.

  However, in the method of forming a thin film by ionizing the zinc oxide-based sintered body, which is the evaporation material (target), by evaporation, splashing of the evaporation material occurs during heating, and particles adhere to the deposited film. There was a problem of causing pinhole defects, and a solution was desired.

  The splash refers to the following phenomenon. That is, when the evaporation material (target) is irradiated with a plasma beam or an electron beam and heated in a vacuum, the evaporation material is vaporized when reaching a certain temperature, and uniform evaporation starts in an atomic state. Splash is a phenomenon in which splashes having a visible size of about several μm to 1000 μm are mixed with a uniform evaporation gas and are ejected from the evaporation material and collide with the deposited film. When this phenomenon occurs, it causes pinhole defects in the deposited film due to the collision of the droplets, which not only significantly deteriorates the homogeneity of the deposited film but also significantly deteriorates the performance as the conductive film.

The cause of such a phenomenon is that bubbles contained in the target explode due to thermal shock or static charge charge-up due to high energy such as plasma beam or electron beam, and this causes splash. It is done.
JP 2004-95223 A JP-A-10-18026

  The present invention has been made in view of the above problems. A zinc oxide-based conductive film is formed by evaporating and ionizing a zinc oxide-based sintered body used as an evaporation material (target) by an ion plating method. In addition, the present invention provides a target capable of preventing or suppressing splash generated during heating and evaporation, stably obtaining a defect-free zinc oxide-based thin film, and providing a useful method for producing the target. An object of the present invention is to provide a method for producing a high-quality zinc oxide-based conductive film using the above-mentioned.

  The ion plating target according to the present invention that has solved the above-mentioned problems is made of a sintered body mainly composed of zinc oxide, and has a (100) plane, (002) plane, and (101) plane in X-ray diffraction analysis. It has a diffraction peak, and one or more half-widths of the diffraction peaks are characterized by being 0.110 degrees or less.

  The sintered body is preferably sintered after preforming a zinc oxide-based powder having a zinc oxide content of 80% by mass or more. Among them, at least one selected from 3B group, 4B group, and 7B group is preferable. Zinc oxide-based powders containing 0.003 to 20% by mass of seed elements are preferable because the conductivity is further enhanced by the doping effect of these elements. The brightness of the target according to the present invention is preferably in the range of 65.0 to 99.5 in terms of L value of brightness measured in CIE 1976 space defined by the International Commission on Illumination.

  The production method of the present invention is an invention that is positioned as a useful production method for the ion plating target, which is fired at 600 to 1600 ° C., has a maximum particle size of 150 μm or less, and an average particle size of 2 to 30 μm. A uniform mixture containing 5 to 99% by mass of a certain zinc oxide-based calcined powder and 1 to 95% by mass of a zinc oxide-based calcined powder having a maximum particle size of 20 μm or less and an average particle size of 0.1 to 2 μm was preformed. Later, there is a point where sintering is performed at 600 to 1600 ° C.

  Moreover, the method of forming a zinc oxide type electrically conductive film by the ion plating method using the said target is also included by the technical scope of this invention.

  According to the present invention, as an ion plating target composed of a sintered body mainly composed of zinc oxide, X-ray diffraction analysis has diffraction peaks on the (100) plane, the (002) plane, and the (101) plane. By using a zinc oxide-based sintered body having a half-value width of 0.110 degrees or less of any of the peaks, a zinc oxide-based conductive film with no splashing and a stable performance can be obtained. .

  The target of the present invention is a zinc oxide-based sintered body used as an evaporation material for ion plating as described above, and is a (100) plane, (002) plane, and (101) plane in X-ray diffraction analysis. It has a feature in that it has a diffraction peak, and one of these diffraction peaks has a half width of 0.110 degrees or less.

  First, regarding the X-ray diffraction intensity of the zinc oxide-based sintered body, zinc oxide has main diffraction peaks on the (100) plane, (002) plane and (101) plane as X-ray diffraction characteristics. These peaks are known and are unique to zinc oxide. However, the full width at half maximum varies significantly depending on the crystal state of the zinc oxide-based sintered body, and crystallization has not progressed sufficiently, and in the case of fine crystals or aggregates of crystals of various sizes, The diffraction peak is broad and the full width at half maximum is increased. On the other hand, as the crystallization progresses and the crystal size increases, the diffraction peaks on each surface become sharp and the half-value width decreases.

  The present inventors have recognized through preliminary experiments that "the splash phenomenon seen when using a zinc oxide-based sintered body as an ion plating target is influenced by the crystallinity of the zinc oxide-based sintered body used. Based on the knowledge that it is strongly received, research was conducted to quantitatively understand the effect of the half-width of each surface on the splash phenomenon.

  As a result, the peak of at least one of the (100) plane, (002) plane, and (101) plane has a half-value width of 0.110 degrees or less, and a sharp diffraction peak is high energy. It was found that the splash generated when receiving the beam was remarkably suppressed, and as a result, a homogeneous and defect-free zinc oxide-based conductive film was obtained. A more preferable half width is 0.105 degrees or less. Further, only one of the three surface peaks may be shown as such a small half-value width, but preferably two surface peaks, more preferably all the half-value widths of the three surface peaks are 0.110. Those that are less than or equal to the degree are confirmed to have even less splash.

  The reason why the splash can be suppressed by reducing the half-value width of the X-ray diffraction peaks on the three surfaces has not been fully elucidated yet, but the following may be considered. That is, the fact that the half width of the X-ray diffraction peak is small means that the crystal particle diameter is uniform, and it seems that the sintered body evaporates uniformly when receiving a high energy beam. In any case, it is clear from the examples described later that the progress state of the zinc oxide crystal reflected in the half width of the diffraction peak has some influence on the splash.

  The zinc oxide-based sintered body used as a target in the present invention may be one obtained by doping zinc oxide with a conductivity-imparting component and imparting conductivity, or an element selected from 3B group, 4B group and 7B group Specifically, a material doped with one or more of B, Al, Ga, In, Si, Ge, Sn, Pb, F, Cl, Br, and I is used. The doping amount of these elements varies depending on the kind of element and the required degree of conductivity and cannot be determined uniformly. However, the standard amount is about 0.003 to 20% by mass, and more preferably about 0.000. It is about 01-10 mass%.

  The zinc oxide-based sintered body is manufactured by mixing at least two types of zinc oxide-based powders, preforming and firing as described in detail later. The L value measured in the CIE 1976 space defined by the Lighting Committee is preferably within a range of 65.0 to 99.5. Incidentally, when the L value is less than 65.0, the doping amount is excessive, and when the L value exceeds 99.5, the doping amount is insufficient, and all of them are slightly insufficient in performance. The L value is considered to affect the crystal size in which the half width of the diffraction peak of the three surfaces defined above is reflected, and as a result, the L value is also considered to affect the splash.

  Next, a useful manufacturing method for obtaining an ion plating target having the above characteristics will be described.

  In the production method of the present invention, as a method for obtaining a target having the above characteristics, a zinc oxide-based fired powder (A) whose firing temperature and particle size are specified and a particle size are specified as described in detail below. A method is used in which the zinc oxide-based green powder (B) is used, and these are uniformly mixed at a predetermined ratio and then sintered at a predetermined temperature.

  Specifically, the zinc oxide-based fired powder (A) is a fired powder that has been fired at 600 to 1600 ° C. and has undergone crystallization, and has a maximum particle diameter of 150 μm or less and an average particle diameter of 2 to 30 μm. While using a baked powder, as a zinc oxide type unbaked powder (B), the unbaked powder whose maximum particle diameter is 20 micrometers or less and whose average particle diameter is 0.1-2 micrometers is used. Then, these zinc oxide-based fired powder (A) and zinc oxide-based unfired powder (B) are blended so as to be in the range of 5 to 99% by mass of the former and 1 to 95% by mass of the latter, and mixed uniformly. Is preformed by an arbitrary method such as a mechanical press or an isostatic press, and then sintered at 600 to 1600 ° C.

  The greatest aim in the above production method is to advance the growth of crystals by firing at a high temperature in advance, and target the zinc oxide-based fired powder (A) that does not cause volume shrinkage in the subsequent sintering step. Zinc oxide green powder (B) used as a skeletal component of (sintered body) and mixed therewith has a relatively small maximum particle size and average particle size, and so-called binder component that is diffusion bonded in the sintering process. These are mixed, preformed and then fired, so that the crystallized zinc oxide-based fired powder (A) is used as a skeletal component, so that at least one of the three surfaces by X-ray diffraction analysis can be obtained. The diffraction peak half-width is to be kept small.

  In order to realize such aim, the production method of the present invention defines the specifications, content ratio and sintering temperature of the zinc oxide-based fired powder (A) and the zinc oxide-based unfired powder (B). The reason is as follows.

  First, the zinc oxide-based fired powder (A) must be fired in advance at 600 to 1600 ° C. This zinc oxide-based fired powder (A) is a skeletal component of the sintered body as described above, and itself needs to be sufficiently crystallized. For that purpose, at least 600 ° C. or higher, Preferably, it must be fired at a temperature of 800 ° C. or higher, and more preferably it is pre-fired at a sintering temperature or higher when obtaining a sintered body.

  The preferable particle size constitution of the zinc oxide-based fired powder (A) is a maximum particle size of 150 μm or less and an average particle size of 2 to 30 μm. This particle size configuration is important for effectively exhibiting the action as the skeletal component of the calcined powder (A). When the maximum particle size exceeds 150 μm or the average particle size exceeds 30 μm, the skeletal component is coarse. Since it is too large in size, the target becomes insufficient in homogeneity, and the strength is insufficient, and the quality stability is insufficient. On the other hand, if the average particle size is too small, the target becomes too dense because it is too fine as a skeleton component. In order to obtain a homogeneous sintered body, the particle size constitution of the skeleton component is more preferably a maximum particle size of 130 μm or less, more preferably 110 μm or less, and an average particle size of 2 to 25 μm, more preferably 2 to 20 μm.

  On the other hand, as the zinc oxide-based unfired powder (B), a powder having a maximum particle size of 20 μm or less and an average particle size of 0.1 to 2 μm is used. This unfired powder (B) is a component that functions as a binder for the fired powder (A) and is sintered in the sintering process after being mixed with the fired powder (A). Is essential. Here, the unsintered state means a state in which a room for sintering is left in the sintering step after mixing with the fired powder (A) and is not fired at all or is completely sintered in a partially fired state. The state that has not reached.

  The unfired powder (B) has a maximum particle size of 20 μm or less and an average particle size of 0.1 to 2 μm because, if the maximum particle size and the average particle size are too large, the baked powder ( In contrast to A), if the sintered body (target) becomes insufficient in strength or loses its shape-retaining property because the function as a binder is difficult to be exhibited, and if the average particle size is too small, excessive particle growth occurs and the particle size Cause non-uniformity. From this viewpoint, the more preferable maximum particle size of the unfired powder (B) is 15 μm or less, more preferably 10 μm or less, and the average particle size is in the range of 0.3 to 2 μm, more preferably 0.5 to 1.5 μm. It is.

  The blending ratio of the zinc oxide-based fired powder (A) and the zinc oxide-based unfired powder (B) is 95 to 1 part by weight, more preferably 10 to 90 parts by weight of the latter with respect to 5 to 99 parts by weight of the former. On the other hand, it is in the range of 90 to 10 parts by mass of the latter, and when the former is too much (that is, when the latter is insufficient), the sintered body (target) is insufficient in strength, and conversely, the former is too little (that is, the latter). In the case where there is too much), excessive grain growth occurs and the crystal grain size becomes non-uniform, and none of them is suitable for the purpose of the present invention. There is no limitation on the mixing method, and a known mixing method using a ball mill, a homogenizer, a Henschel mixer or the like may be employed.

  There is no restriction on the mixing method when mixing elements selected from Group 3B, Group 4B, and Group 7B, and one or more selected from the above elements are blended in an appropriate amount with respect to the zinc oxide powder. Then, they may be mixed using a known mixing device such as a ball mill, a homogenizer, a Henschel mixer. The above-mentioned selective elements are mixed in order to increase the conductivity of the zinc oxide sintered body by adding appropriate amounts of these elements and to improve the properties as a conductive material. In order to exhibit, it is preferably 0.003 mass% or more, more preferably 0.01 mass% or more with respect to the zinc oxide powder. However, if the content of these elements is too large, an increase in the effect according to the added amount is not recognized, and conversely, obstacles such as acting as impurities and inhibiting conductivity appear, so at most 20% by mass. In the following, it is preferable to keep the content to 15% by mass or less.

  The zinc oxide-based calcined powder (A) and the zinc oxide-based calcined powder (B) are blended within the above-mentioned preferred range, or further blended with the above selected elements and mixed uniformly, and then preformed at a predetermined temperature. If heat-sintered, the target which consists of complex oxide which has moderate intensity | strength and has the predetermined diffraction peak half value width mentioned above by X-ray diffraction analysis can be obtained.

  The sintering temperature is preferably 600 ° C to 1600 ° C. If the sintering temperature is less than 600 ° C., sufficient sintering does not occur, and the sintered body itself tends to collapse. However, if the sintering temperature exceeds 1600 ° C. and becomes too high, evaporation of zinc oxide occurs in the firing furnace and contaminates the firing furnace. From such a viewpoint, a more preferable sintering temperature is 700 ° C. or higher and 1500 ° C. or lower, more preferably 800 ° C. or higher and 1400 ° C. or lower. The sintering time is not particularly limited, but usually about 2 hours or more is sufficient, and typically about 3 hours or more. Although there is no upper limit to the time, it is totally useless to extend the time to 5 hours or more, so normally about 5 hours or less is adopted. The sintering atmosphere may be an air atmosphere, a reducing atmosphere, or an inert gas atmosphere.

  The target of the present invention thus obtained does not crack or collapse due to thermal shock even when heated by a high energy beam such as a plasma beam or an electron beam as described above, and may cause a splash phenomenon. Therefore, the obtained zinc oxide-based conductive film will be homogeneous and high-performance without pinhole defects, and in the near future, it can be expected to be put into practical use as an inexpensive conductive film material that can be replaced with an ITO film.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention.

Example 1
65 parts by mass of zinc oxide-based calcined powder having a maximum particle size of 75 μm or less and an average particle size of 10 μm and heated and calcined at about 1400 ° C. for 3 hours; 35 parts by mass (average particle diameter: about 1 μm, unfired powder) was used, and sufficiently mixed using a ball mill.

  Then, after press-molding using a mechanical press at a press pressure of 20 MPa, a zinc oxide sintered body having a diameter of 30.7 mm and a thickness of 20 mm was manufactured by sintering at 1200 ° C. for 5 hours in an air atmosphere.

  This zinc oxide sintered body was subjected to an X-ray diffraction analysis by ATX-G manufactured by Rigaku Corporation and X'Pert PRO MRD manufactured by PANalytical, and the half-value width of each diffraction peak on the (100), (002), and (101) planes was determined. When determined, they were 0.106, 0.108, and 0.099, respectively. Moreover, L value measured in CIE 1976 space of this zinc oxide sintered compact was 98.7.

  When this zinc oxide sintered body is loaded into an ion plating apparatus and evaporated by irradiating with a 6 kV electron beam, it is observed for 2 minutes from a viewing window on the side of the chamber, and no splash is observed. It was.

Example 2
A maximum particle size of 106 μm or less and an average particle size of 15 μm, and 65 parts by mass of zinc oxide-based calcined powder heated and calcined at about 1300 ° C. for 3 hours, and one type of zinc oxide manufactured by Hakusui Tech Co., Ltd. 35 parts by mass (average particle size: about 1 μm, unfired powder) was used, and sufficiently mixed using a Henschel mixer.

  Then, after pre-molding with a mechanical press at a press pressure of 20 MPa, sintering was performed at 1200 ° C. for 5 hours in an air atmosphere to produce a zinc oxide sintered body having a diameter of 30.7 mm and a thickness of 20 mm.

  When the X-ray diffraction characteristics of the obtained zinc oxide sintered body were measured in the same manner as described above, the half-value widths of the diffraction peaks on the (100), (002), and (101) planes were 0.116 and 0, respectively. 104, 0.109. Moreover, L value measured in CIE 1976 space of this zinc oxide sintered compact was 98.5.

  When this zinc oxide sintered body is loaded into an ion plating apparatus and evaporated by irradiating with a 6 kV electron beam, it is observed for 2 minutes from a viewing window on the side of the chamber, and no splash is observed. It was.

Example 3
A maximum particle size of 75 μm or less and an average particle size of 10 μm, 63 parts by mass of zinc oxide-based calcined powder fired and calcined at about 1400 ° C. for 3 hours, and 1 type of zinc oxide manufactured by Hakusui Tech Co., Ltd. 34 parts by mass of an average particle size: about 1 μm, unfired powder) and 3 parts by mass of gallium oxide powder (manufactured by Kishida Chemical Co., Ltd.) were used and sufficiently mixed using a ball mill.

  Then, after pre-molding with a mechanical press at a press pressure of 20 MPa, a zinc oxide sintered body having a diameter of 32.0 mm and a thickness of 20 mm was manufactured by sintering at 1200 ° C. for 5 hours in an air atmosphere.

  When the X-ray diffraction characteristics of the obtained zinc oxide sintered body were measured in the same manner as described above, the half-value widths of the diffraction peaks on the (100), (002), and (101) planes were 0.104 and 0, respectively. .101, 0.102. Moreover, L value measured in CIE 1976 space of this zinc oxide sintered compact was 87.5.

  When this zinc oxide sintered body is loaded into an ion plating apparatus and evaporated by irradiating with a 6 kV electron beam, it is observed for 2 minutes from a viewing window on the side of the chamber, and no splash is observed. It was.

Comparative Example 1
The maximum particle size is 250 μm or less and the average particle size is 35 μm, and 65 parts by mass of zinc oxide-based calcined powder that is heated and calcined at about 1400 ° C. for 3 hours; 35 parts by mass (average particle diameter: about 1 μm, unfired powder) was used, and sufficiently mixed using a ball mill.

  Then, after pre-molding at a press pressure of 20 MPa by a mechanical press, sintering was performed at 1200 ° C. for 5 hours in an air atmosphere to produce a zinc oxide sintered body having a diameter of 31.9 mm and a thickness of 20 mm.

  When the X-ray diffraction characteristics of the obtained zinc oxide sintered body were measured in the same manner as described above, the half-value widths of the diffraction peaks on the (100), (002), and (101) planes were 0.118 and 0, respectively. 125, 0.116. Moreover, L value measured in CIE 1976 space of this zinc oxide sintered compact was 98.4.

  When this zinc oxide sintered body is loaded into an ion plating apparatus and evaporated by irradiating it with a 6 kV electron beam, it is observed from the observation window on the side of the chamber for 2 minutes, and the occurrence of splash is observed 26 times. It was done.

Comparative Example 2
80 parts by mass of zinc oxide-based calcined powder having a maximum particle size of 250 μm or less and an average particle size of 35 μm and heated and calcined at about 1400 ° C. for 3 hours, and 1 type of zinc oxide manufactured by Hakusui Tech Co., Ltd. 20 parts by mass (average particle size: about 1 μm, unfired powder) was used, and sufficiently mixed using a ball mill.

  Then, after preforming with a mechanical press at a press pressure of 20 MPa, sintering was performed at 1200 ° C. for 5 hours in an air atmosphere to produce a zinc oxide sintered body having a diameter of 32.3 mm and a thickness of 20 mm.

  The X-ray diffraction characteristics of the obtained zinc oxide sintered body were measured in the same manner as described above, and the half-value widths of the diffraction peaks on the (100), (002), and (101) planes were determined. 0.118 and 0.116. Moreover, L value measured in CIE 1976 space of this zinc oxide sintered compact was 98.3.

  When this zinc oxide sintered body is loaded into an ion plating apparatus and evaporated by irradiating a 6 kV electron beam, it is observed for 2 minutes from the observation window on the side of the chamber, and the occurrence of splash is observed 30 times. It was done.

Comparative Example 3
The maximum particle size is 250 μm or less, the average particle size is 35 μm, 63 parts by mass of zinc oxide-based calcined powder heated and calcined at about 1400 ° C. for 3 hours, and 1 type of zinc oxide (maximum particle size: 20 μm or less, 34 parts by mass of an average particle size: about 1 μm, unfired powder) and 3 parts by mass of gallium oxide powder (manufactured by Kishida Chemical Co., Ltd.) were used and sufficiently mixed using a ball mill.

  Then, after preforming with a mechanical press at a press pressure of 20 MPa, sintering was performed at 1200 ° C. for 5 hours in an air atmosphere to produce a zinc oxide sintered body having a diameter of 32.5 mm and a thickness of 20 mm.

  When the X-ray diffraction characteristics of the obtained zinc oxide sintered body were measured in the same manner as described above, the half-value widths of the diffraction peaks on the (100), (002), and (101) planes were determined. 116, 0.120, and 0.114. Moreover, L value measured in CIE 1976 space of this zinc oxide sintered compact was 86.0.

  When this zinc oxide sintered body is loaded into an ion plating apparatus and evaporated by irradiating a 6 kV electron beam, it is observed for 2 minutes from the observation window on the side of the chamber, and the occurrence of splash is observed 22 times. It was done.

Claims (6)

  It consists of a sintered body mainly composed of zinc oxide and has diffraction peaks on the (100) plane, (002) plane and (101) plane in X-ray diffraction analysis, and any one or more half-value widths of the diffraction peaks are 0 A target for ion plating for producing a zinc oxide-based conductive film characterized by being 110 ° or less.   The target according to claim 1, wherein the sintered body is obtained by preforming and sintering a zinc oxide-based powder having a zinc oxide content of 80% by mass or more.   The target according to claim 1 or 2, wherein the zinc oxide-based powder contains 0.003 to 20 mass% of at least one element selected from Group 3B, 4B, and 7B.   The target according to any one of claims 1 to 3, wherein an L value of brightness measured in a CIE 1976 space defined by the International Commission on Illumination is 65.0 to 99.5. A method for producing the target for ion plating according to any one of claims 1 to 4, wherein the target is fired at 1300 to 1600 ° C, the maximum particle size is 150 µm or less, and the average particle size is 2 to 30 µm. A uniform mixture containing 5 to 99% by mass of a certain zinc oxide-based calcined powder and 1 to 95% by mass of a zinc oxide-based calcined powder having a maximum particle size of 20 μm or less and an average particle size of 0.1 to 2 μm is preformed. , Sintering at 600 to 1600 ° C., a method for producing a target for producing a zinc oxide-based conductive film.   A method for producing a zinc oxide-based conductive film, wherein the target according to any one of claims 1 to 4 is used to form a zinc oxide-based conductive film by an ion plating method.