JP2010204380A - Light reflecting mirror and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light reflecting mirror for improving durability and maintaining the merit which is the high reflectance of a silver-based light reflecting mirror for a long period of time by preventing corrosion by moisture or the like, and a method of manufacturing the light reflecting mirror. <P>SOLUTION: The silver alloy light reflecting mirror of a multilayer film structure compatibly achieves high reflectance and high durability by using a prescribed silver alloy whose corrosion resistance against moisture is more excellent than silver and increasing adhesiveness and denseness of respective constitution films to be formed further. Also, there is provided the method of manufacturing the light reflecting mirror. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light reflecting mirror suitable for use in imaging and illumination in a projector, a projection television, and the like, and a method for manufacturing the same.

  In various optical apparatuses such as projectors that project images, a light reflecting mirror having silver (Ag) or aluminum (Al) as a reflection film has been conventionally used. Among them, silver has a high reflectance in the visible light region and has excellent reflection characteristics as a light reflecting mirror. However, there is a problem that the silver reflective film has a low reflectance in the visible light region having a wavelength of about 500 nm or less, and is easily corroded by moisture or the like and has poor durability.

To solve these problems, an aluminum oxide (Al ₂ O ₃ ) layer is provided for the purpose of blocking moisture and improving durability, or improving the reflectance in the visible light region of a wavelength of about 500 nm or less. A method of providing a reflectance adjustment layer having a multilayer structure made of aluminum oxide, zirconium dioxide, silicon dioxide or the like is disclosed (Patent Documents 1 and 2).

  However, these methods are effective in improving the reflectance in the visible light region having a wavelength of about 500 nm or less, but are not sufficient in terms of durability such as corrosion resistance. In particular, when the substrate is made of a resin, the resin is moisture permeable, so that the problem that water gradually permeates with time and the reflective film is corroded cannot be sufficiently solved. In addition, the adhesion between the reflective film and a layer (film) called a protective film or a reflectance adjustment layer, and the denseness of the protective film or the reflectance adjustment layer are insufficient. The problem has not been solved sufficiently.

  Therefore, the present applicant developed a light reflecting mirror that prevents protrusion of moisture by providing protrusions on the periphery of the surface of the reflecting film, and filed a patent application (Patent Document 3). However, since the use or application scene of this technology is limited, more essential problem solving has been desired.

JP-A-5-127004 JP 2004-219974 A JP 2006-301232 A

  As described above, the problem of preventing corrosion of the light reflecting mirror due to moisture and improving durability has not been sufficiently solved. Accordingly, an object of the present invention is to solve the problem of improving the durability and to provide a light reflecting mirror that can maintain the advantage of high reflectivity of the silver-based light reflecting mirror for a long period of time and a method for manufacturing the same.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive research, and as a result, a silver alloy is used as the reflection film, and the surface roughness of the reflection film is set to 2 nm or less in terms of Ra value. A highly durable light reflecting mirror that can be solved was developed, and an effective manufacturing method of the light reflecting mirror by establishing a predetermined process was established to complete the present invention.

  That is, according to the first invention of the present invention, the substrate surface has an adhesion improving film, a silver alloy reflective film, and a reflection increasing film, and the reflection on the side in contact with the reflection increasing film is provided. A light reflecting mirror having a Ra value on the film surface of 2 nm or less is provided.

  According to the second invention, the reflective film is preferably a silver alloy having bismuth.

  According to 3rd invention, it is preferable that the said base material is either super steel materials, such as glass, a thermoplastic resin, a thermosetting resin, an infrared rays transparent metal, aluminum, carbon steel, or alloy steel.

  According to the fourth invention, it is preferable that the (111) peak intensity by X-ray diffraction on the side where the Ra value is 2 nm or less is 20 times or more of the total of other peak intensities.

According to the fifth invention, the adhesion improving film is made of Cu, Cr, CrO, Cr ₂ O ₃ , Y ₂ O ₃ , La ₂ Ti ₃ O ₈ , SiO ₂ , TiO ₂ , and Al ₂ O _3. Preferably, the adhesion improving film is a single layer or a multilayer film of four or less layers.

According to the sixth invention, the reflection increasing film is made of a group consisting of ZrO ₂ , Y ₂ O ₃ , MgF ₂ , LaTiO ₃ , La ₂ Ti ₃ O ₈ , SiO ₂ , TiO ₂ , and Al ₂ O _3. It is at least one selected, and the reflection enhancing film is preferably a single layer or a multilayer film of five layers or less.

According to the seventh invention, it is preferable that an intermediate film selected from Y ₂ O ₃ , MgF ₂ , Al ₂ O _3, or SiO ₂ is provided between the silver alloy reflective film and the reflection increasing film. .

  According to the eighth invention, it is preferable that the uppermost layer of each film formed on the surface of the substrate has a water repellent film of 15 to 40 nm.

  According to a ninth aspect of the invention, the method includes the step of forming the adhesion improving film on the surface of the base material, the step of forming the reflective film of the silver alloy, and the step of forming the reflection increasing film. All the steps are performed continuously, and the method of manufacturing the light reflecting mirror is provided in which the temperature of the substrate is maintained at 70 ° C. or lower during all the steps.

  According to a tenth aspect of the present invention, it is preferable that the method for manufacturing the light reflecting mirror further includes a step of forming the intermediate film.

  According to the present invention, since the Ra value on the surface of the silver alloy reflecting film is 2 nm or less, the adhesion with the reflection increasing film is improved, and each film constituting the light reflecting mirror of the present invention is densely formed. By doing so, it is possible to highly prevent moisture from entering the reflective film made of a silver alloy. Furthermore, since the silver alloy according to the present invention has better corrosion resistance to moisture than silver, even if moisture penetrates into the reflective film somewhat, without causing deterioration such as whitening due to corrosion as in the conventional silver reflective film, There is a dramatic effect that the reflectance can be maintained well.

It is a schematic sectional drawing which shows the light reflection mirror which concerns on one Embodiment of this invention. It is a schematic sectional drawing which shows the light reflection mirror which concerns on another embodiment of this invention. It is a conceptual diagram which shows an example of the thin film formation apparatus for manufacturing the light reflection mirror of this invention. It is explanatory drawing which shows the general | schematic process of film | membrane (except water-repellent film | membrane) formation of this invention. It is a perspective view which shows one example of application of the light reflection mirror of this invention.

  Hereinafter, embodiments of the present invention will be described in detail. First, formation of each layer (film | membrane) which comprises the light reflection mirror of this invention with reference to FIG. 1 showing sectional drawing of the light reflection mirror of this invention is demonstrated. First, the adhesion improving film 51, the reflective film 52, and the reflection increasing film 53 are formed on the surface of the base material 50 using the thin film forming apparatus shown in FIG. Preferably, the layers are stacked in this order (FIG. 1). Further, when it is desired to further improve the durability, the intermediate film 54 and the water repellent film 55 are formed as shown in FIG. The material or composition of the substrate and each film, and the method for forming each film will be described below in order.

  The base material 50 is a substrate that is formed by laminating a thin film such as an intermediate film or a water-repellent film on the surface thereof, such as an adhesion improving film, a reflective film, and a reflection increasing film, and if necessary, The material is not particularly limited as long as these thin films can be formed, and examples thereof include glass, a thermoplastic resin, a thermosetting resin, an infrared transmitting metal, aluminum, and a super steel material such as carbon steel or alloy steel. Examples of these alloy steels include stainless steels such as chrome steel, nickel chrome steel, nickel chrome molybdenum steel, and manganese molybdenum steel. These cast steels can also be mentioned. In order to increase the adhesion to the thin film, the surface of the base material is preferably smooth. For example, a surface-polished product is suitable for a glass material. As the infrared transmitting metal, silicon, germanium, chalcogenite glass, and the like are preferable in terms of surface smoothness and adhesion to the thin film.

  As the thermoplastic resin, acrylic resin such as polyacrylic acid ester or polymethacrylic acid ester, ABS resin, engineering plastic such as polycarbonate or nylon, super engineering plastic such as polyphenylene sulfide, or the like can be used.

  As the thermosetting resin, phenol resin, epoxy resin, polyurethane, or the like can be used. Alternatively, the thermosetting resin includes these thermosetting resins and at least one selected from unsaturated polyester resins and curing agents that cure the resins, thermoplastic resins, inorganic fillers, and reinforcing fibers. It may be a resin composition.

The adhesion improving film 51 of the present invention is formed on the surface of the substrate. The adhesion improving film is at least one selected from the group consisting of Cu, Cr, CrO, Cr ₂ O ₃ , Y ₂ O ₃ , La ₂ Ti ₃ O ₈ , SiO ₂ , TiO ₂ , and Al ₂ O _3. It is preferable that it is one or more layers. Two or more layers are more preferable in terms of preventing moisture penetration. On the other hand, it is preferable that the number of layers is not more than four layers in view of the point that the effect cannot be expected even if it is more than that and the economical point.

In terms of high adhesion, Cu (copper), Cr (chromium), and Y ₂ O ₃ (yttrium oxide) are preferable. In the case of Cu, the film thickness is preferably 50 nm or more and 80 nm or less from the viewpoint of the moisture blocking effect. In the case of Cr or Y ₂ O ₃ , it is preferably 18 nm or more and 70 nm or less from the viewpoint of film formation. It is more preferable in terms of corrosion resistance to form two or more layers of adhesion improving films each having a suitable thickness with these elements, oxides, or both. The total thickness of the adhesion improving film is preferably 200 nm or less from the viewpoint of reducing the weight of the light reflecting mirror and the economical efficiency.

  The adhesion improving film 51 has a function of improving the adhesion between the reflective film 52 and the base material 50 as described above, and effectively preventing moisture from passing through the base material 50 and penetrating into the reflective film 52. .

  The reflective film 52 of the silver alloy of the present invention is formed on the surface of the adhesion improving film 51. As the silver alloy, an alloy containing one or more of bismuth (Bi), gold, copper, palladium, or platinum is preferable. A bismuth-containing silver alloy is preferred in terms of corrosion resistance to moisture and high spectral reflectance. An Ag—Bi (bismuth) alloy is more preferable, and a Bi content is more preferably 0.5 to 5% in that a reflectivity of 97% or more can be obtained in the visible light region.

  The thickness of the silver alloy reflective film 52 is preferably 70 nm or more, and more preferably 100 nm or more in that light transmittance is low and high reflectance can be obtained. On the other hand, even if it exceeds 200 nm, the reflectance is not improved, and also in terms of material cost, it is preferably 200 nm or less, and more preferably 150 nm or less.

  It improves the adhesion between the silver alloy reflective film 52 and the reflection increasing film formed on the surface of the reflective film 52, prevents the permeation of moisture from the peripheral edge of the light reflecting mirror, and has a high reflectance. In terms of ensuring, the surface of the reflection film 52 on the reflection increasing film forming side preferably has a surface roughness of 2 nm or less in terms of Ra value. Here, Ra value means the arithmetic mean roughness prescribed | regulated by JISB0601-2001. If the surface is completely smooth and can be measured, the Ra value is 0 nm. Therefore, although it is practically impossible, the ideal value of the Ra value is 0 nm. That is, the Ra value is preferably closer to 0 nm if it is 2 nm or less. In the present invention, the Ra value is measured by observation with an atomic force microscope (AFM). An atomic force microscope uses the fact that when a cantilever with a probe is brought close to the sample surface, the cantilever bends due to the atomic force, and the displacement is detected by laser reflected light. A microscope that can be imaged with. That the surface roughness measured with such an atomic force microscope is 2 nm or less means that the reflective film 52 of the silver alloy is close to an ideal smooth surface.

  The (111) peak intensity by X-ray diffraction of the surface of the reflective film 52 on the side where the Ra value is 2 nm or less is 20 times or more the total of other peak intensities. This means that the orientation of the silver alloy crystal is high, the crystal density is high and dense, and the properties of the reflective film of the silver alloy are homogeneous. As a result, absorption and scattering of light into the film, which is a major cause of a decrease in reflectance, are suppressed. Light absorption means that light energy is converted into heat in the film and lost, and the more defects such as impurities in the film, the more light is absorbed. Therefore, the definition of the peak intensity defines the small number of defects such as impurities.

The reflection increasing film 53 of the present invention is formed on the surface of the reflecting film 52 on the side opposite to the adhesion improving film 51. The reflection increasing film is at least one selected from the group consisting of ZrO ₂ , Y ₂ O ₃ , MgF ₂ , LaTiO ₃ , La ₂ Ti ₃ O ₈ , SiO ₂ , TiO ₂ , and Al ₂ O ₃ . One or more layers are preferable. In order to complement the reflectance of the silver alloy reflective film and improve the reflectance in the visible light region, it is more preferable to use a compound having a different refractive index to form a multilayer film of two or more layers. On the other hand, it is preferably 5 layers or less from the viewpoint that the effect cannot be expected even if it is more than that, and economical efficiency. The thickness of the reflection increasing film 53 is appropriately determined depending on the refractive index and the wavelength of light, but is preferably 10 to 70 nm for each layer forming the reflection increasing film from the viewpoint of improving the reflectance.

  The reflection increasing film 53 also has an effect as a protective film for protecting the reflective film 52, prevents moisture contained in the atmosphere from penetrating into the reflective film 52, and causes corrosion or the like in the reflective film 52. Can be effectively prevented. Therefore, when three or more reflection increasing films are formed, the film thickness per layer is preferably 10 nm or more and 20 nm or less, and more preferably 18 nm or less, in terms of the balance between reflectance and moisture penetration prevention.

Furthermore, if necessary, an intermediate film 54 selected from Y ₂ O ₃ , MgF _2, or SiO ₂ can be formed between the reflective film 52 and the reflection increasing film 53 as shown in FIG. The intermediate film has high adhesion to both the reflection film and the reflection enhancement film, and functions to prevent moisture penetration to a higher degree. In order to effectively exhibit the function, the film thickness is 20 nm or more, preferably 50 nm or more, more preferably 65 nm or more. Moreover, since the performance improvement is not recognized even if it is more than that, it is preferable that it is 100 nm or less.

  Furthermore, when the intermediate film is a metal oxide, the filling density is preferably 0.98 or more in order to exhibit the function. The packing density will be described in detail in examples described later.

  If necessary, a water repellent film 55 having a thickness of 15 to 40 nm can be formed on the uppermost layer of each film formed on the surface of the substrate. If the film thickness is within this range, it is possible to effectively prevent moisture penetration and further improve the corrosion resistance and durability of the light reflecting mirror. The water repellent film is preferably formed of a fluorine-containing compound or a compound containing fluorine and silicon.

  A method of forming each of the above films (thin films) on the substrate 50 and creating a light reflecting mirror will be described in detail below. FIG. 3 shows an outline of a thin film forming apparatus used for producing the light reflecting mirror of the present invention. In addition, about the chamber 11 of FIG. 3, the inside is schematically shown with the sectional drawing. In the following thin film forming method, the evaporation material 9 and, if necessary, the film forming conditions are changed so that the film can be continuously formed on the substrate 50 by one thin film forming apparatus.

First, the case where the thin film of the adhesion improving film 51 is formed on the surface of the substrate 50 will be described. In the lower part of the chamber 11 in the thin film forming apparatus shown in FIG. In addition, a crucible 26 is also provided that irradiates an electron beam with an electron gun 27 instead of heating with the boat 1 to evaporate the evaporation material 9. The boat 1 holding the evaporating material 9 or the crucible 26 holding the evaporating material 9 is referred to as an evaporation source 20. A base material holding part 2 for holding the base material 50 is provided in the upper part of the chamber 11 so as to face the evaporation source 20. The evaporation material 9 for forming the adhesion enhancing film _{51, Cu, Cr, CrO,} Cr 2 O 3, Y 2 O 3, La 2 Ti 3 O 8, SiO 2, TiO 2, or _Al 2 _{O 3} Can be used. When the adhesion improving film 51 is a multilayer having different film components, these metal or metal oxide thin films are sequentially formed on the substrate 50 by the method described below.

  The base material holder 2 is made of a conductive material so that high frequency power from a high frequency power supply source (RF) 5 is applied via a matching device (MN) 4 and a capacitor 7 as a DC shielding filter. It has become. The capacitor 7 may function as a part of the matching circuit using a variable capacitor. Furthermore, the cathode side of the direct-current voltage application power source (DC) 6 is connected to the base material holding part 2 via a coil 8 as a high-frequency shielding filter. The terminal on the opposite side of the base material holding part 2 of the high-frequency power supply source 5 is connected to the anode side of the DC voltage application power source 6, and these are grounded.

  The boat 1 is made of, for example, a material having a high electrical resistance, and generates heat for evaporating the evaporating material 9 upon receiving power supply from a heating power source 3 including, for example, an AC power source. The boat 1 is further connected to the anode side of the DC voltage application power source 6. As another method, as described above, the evaporation material 9 can be evaporated by irradiating the evaporation material 9 accommodated and held in the crucible 26 from the electron gun 27. In FIG. 3, a dotted arrow from the electron gun 27 to the evaporating material 9 held in the crucible 26 represents the state of electron beam irradiation.

The space in the chamber 11 is evacuated by the vacuum pump 14 through the exhaust duct 12 and the exhaust valve 13 and is in a predetermined vacuum state during the thin film formation period. In order to supply an inert gas (for example, argon gas) and a reactive gas (for example, oxygen gas) into the chamber 11, the chamber 11 is supplied with an inert gas via a flow rate control device (MFC) 24 and a gas supply pipe 25. An active gas supply source 21 and a reactive gas supply source 23 are connected. Supply / stop from the inert gas supply source 21 is performed by opening and closing the valve 21a. Supply / stop from the reactive gas supply source 23 is performed by opening and closing the valve 23a. The reactive gas is supplied only when forming an adhesion improving film of a metal oxide such as CrO, Y ₂ O ₃ , SiO ₂ , TiO ₂ , and Al ₂ O ₃ , and improving the adhesion of Cu and Cr. When the film is formed, only the inert gas is supplied without supplying the reactive gas.

The degree of vacuum in the chamber 11 is measured by a vacuum gauge 15, and based on the output of the vacuum gauge 15, the flow rate control device 24 is controlled by a control device 30 composed of a microcomputer or the like. Thus, the gas supply amounts from the inert gas supply source 21 and the reactive gas supply source 23 are controlled so that the degree of vacuum in the chamber 11 is maintained at a predetermined value. In order to obtain the dense adhesion improving film 51, the degree of vacuum when forming the film (layer) in the chamber 11 is 1.0 × 10 ^{−3 to} 5.0 × 10 ⁻² Pa, preferably 5.0 ×. It is good that it is 10 ^{< -3} > -3.0 * 10 ^<-2 > Pa. The oxygen gas concentration is adjusted within a range of about 1.0 × 10 ^{−2 to} 3.0 × 10 ⁻² Pa.

  In order to measure the thin film formation speed on the surface of the substrate 50, a film thickness monitor 17 is provided in association with the substrate holder 2. The output signal of the film thickness monitor 17 is input to the control device 30, and the control device 30 controls the output of the heating power source 3 based on the output of the film thickness monitor 17. Thus, the evaporation amount of the evaporation material 9 is controlled by controlling the amount of current supplied to the boat 1 or adjusting the current value of the electron gun 27 so that the thin film formation speed becomes a desired value. Adjusted. In order to obtain the dense adhesion improving film 51, the formation rate of the thin film is 1 to 20 Å / second, preferably 2 to 15 Å / second. Hereinafter, taking the evaporation of the evaporation material 9 by heating the boat 1 as an example, the film formation procedure and the state in the chamber 11 at that time will be described in more detail.

The high-frequency power supply source 5 may be a high-frequency power source having a frequency of 10 to 50 MHz, for example, but may be set to 13.56 MHz, for example, and an output of 20 to 20 per unit area (cm ² ) of the substrate holding unit 2 as a discharge electrode. A high frequency power of 200 mW, preferably 25 to 150 mW, is applied to the substrate holding unit 2. The preferable output range varies depending on the type of the evaporating material 9 and the size of the base material holding unit 2, and is thus set appropriately within the above range. When a high-frequency electric field corresponding to this is formed in the chamber 11, plasma composed of the gas supplied from the gas supply pipe 25 and the evaporated material evaporated from the evaporation material 9 is generated in the chamber 11. Among the ionized particles in the plasma, positively charged particles are attracted to the surface of the substrate 50 by the DC bias applied to the substrate holding unit 2 from the DC voltage application power source 6. The applied voltage from the DC voltage applying power source 6 is 100 to 400V, preferably 180 to 230V.

  On the other hand, the dissociated electrons in the plasma are attracted to the boat 1 connected to the anode side of the DC voltage application power source 6. At this time, since the evaporation material 9 continuously evaporates from the evaporation source 20, a light emitter having a shape in which a plasma foot falls to the evaporation source 20 due to the collision between the evaporated particles and the electrons is the evaporation source 20. Can be seen in the vicinity of The electrons collected near the evaporation source 20 are sucked into the boat 1 that is grounded and connected to the anode side, and collide with the evaporation material 9 on the boat 1. As a result, evaporation of the evaporation material 9 is promoted by heating by the boat 1 and collision of electrons. That is, an effect of promoting evaporation at a low temperature (deposition assist effect) by concentrated electron collision with the evaporation material 9 can be obtained.

  As shown in FIG. 3, the chamber 11 is not connected to any of the DC voltage application power source 6 and the high frequency power supply source 5 and is not grounded. That is, the chamber 11 is in an electrically floating state. For this reason, high frequency discharge does not occur between the base material holder 2 and the chamber 11, and charged particles in the plasma in the chamber 11 are not attracted to the inner wall of the chamber 11. Accordingly, positively-charged particles or positively-charged particles in the plasma are efficiently guided to the surface of the substrate 50, and electrons that are negatively charged particles in the plasma are transferred to the evaporation material 9 on the boat 1. It will be guided intensively. Thereby, while being able to implement | achieve favorable thin film formation, the evaporation promotion of the evaporation material 9 by an electron beam can be performed efficiently. Furthermore, it is possible to suppress the evaporation material from adhering to the inner wall of the chamber 11.

  When the plasma is stabilized in the chamber 11, the evaporation material 9 evaporates so as to be sucked up by the plasma by irradiation of the electron beam from the plasma onto the evaporation material 9. Therefore, the control device 30 reduces the output of the heating power source 3 based on the output of the film thickness monitor 17 in order to keep the deposition speed of the evaporation material 9 that adheres to the substrate 50 constant. That is, the energization current or energization voltage to the boat 1 is lowered. Thereby, the evaporation rate is adjusted.

  Since the evaporation of the evaporation material 9 is promoted by the electron beam supplied from the plasma, the heating current value of the boat 1 can be kept low, so that the evaporation of the evaporation material 9 is continuously maintained at a relatively low heating temperature. It is possible to form a thin film by vapor deposition utilizing the action of plasma.

  A feature of thin film formation in this apparatus is a method for supplying an inert gas to the chamber 11. That is, in the initial stage of thin film formation, when the gas is supplied from the gas supply pipe 25 to the chamber 11 at a relatively large flow rate and the evaporation from the evaporating material 9 becomes active, the gas supply amount from the gas supply pipe 25 decreases. As a result, in the initial stage of thin film formation in which evaporation from the evaporation material 9 is not active, an inert gas plasma supplied from the gas supply pipe 25 is formed in the chamber 11. When evaporation from the evaporating material 9 becomes active, the amount of gas supplied from the gas supply pipe 25 decreases, and plasma having a composition in which the evaporated particles from the evaporating material 9 become dominant is formed in the chamber 11. .

  In this manner, by introducing the inert gas into the chamber 11 at the initial stage of thin film formation, stable plasma can be rapidly formed in the chamber 11. Thereby, since the thin film formation using the action of plasma can be performed from the initial stage, the thin film of the adhesion improving film 51 having good adhesion can be formed on the surface of the substrate 50.

  FIG. 4 is a diagram for explaining a more specific process for forming a thin film. This figure describes an example of a process for forming a thin film while supplying an inert gas from the inert gas supply source 21 into the chamber 11 when the thin film is formed on the surface of the substrate 50. Specifically, FIG. 4A shows the change over time of the supply amount of argon gas or oxygen gas, FIG. 4B shows the change over time in the degree of vacuum in the chamber 11, and FIG. ) Shows the time change of the heating current value of the boat 1 or the electron gun 27. Further, T1 is a period in which the gas (air) in the chamber is exhausted and decompressed prior to evaporation of the evaporating material 9, and T2 is a period in which the boat is heated or an electron gun is used to evaporate the evaporating material 9. The period during which the evaporation material 9 is irradiated, and T3 indicates the period during which film formation proceeds by the evaporated evaporation material 9.

In the period T1 before the start of the thin film formation process, the control device 30 opens the exhaust valve 13, the pressure in the chamber 11 is reduced by the vacuum pump 14, and the degree of vacuum in the chamber 11 is, for example, about 10 ⁻³ Pa. Retained. From this state, the control device 30 opens the valves 21 a and 23 a at time t <b> 10 and starts supplying gas from the inert gas supply source 21 and the reactive gas supply source 23. After this gas supply is started, the control device 30 monitors the output signal of the vacuum gauge 15 so as to maintain the degree of vacuum in the chamber 11 at, for example, 1.5 × 10 ⁻² Pa. The flow controller 24 is controlled.

  Thus, plasma is generated in the chamber 11 by the high-frequency electric field applied from the high-frequency power supply source 5 during the period T2 when the energization of the boat 1 is started and the evaporation material 9 is heated. The ionized inert gas atoms and molecules in the plasma are guided to the substrate 50 by the DC bias applied to the substrate holding unit 2 from the DC voltage application power source 6. If the inert gas atoms or molecules collide with the base material 50 and an undesired temperature rise of the base material 50 occurs during the period T2, the shutter 18 is provided below the base material 50, What is necessary is just to block the inert gas which goes to 50.

  In the period T2, the control device 30 controls the heating power source 3 and starts energizing the boat 1. Along with this, the heating current value to the boat 1 rises and, for example, the current value reaches a maximum at the end of the period T2. At time t11 when the plasma in the chamber 11 is stabilized, the shutter 18 is opened by a driving device (not shown) under the control of the control device 30, thereby starting the formation of a thin film. Since the evaporated particles are led into the plasma by the evaporation of the evaporation material 9, if the gas is supplied into the chamber 11 from the gas supply pipe 25 at a constant flow rate, the degree of vacuum in the chamber 11 is lowered.

However, the control device 30 controls the flow rate control device 24 so that the degree of vacuum in the chamber 11 is maintained at a constant value (for example, 1.5 × 10 ⁻² Pa), and supplies gas via the gas supply pipe 25. Adjust the amount. As a result, as the amount of evaporation from the evaporation material 9 increases, the amount of inert gas introduced into the chamber 11 decreases as indicated by reference symbol A. Therefore, at the beginning of the period T3 during which the thin film is formed, the composition of the plasma is governed by the inert gas, but the composition of this plasma is a composition governed by the evaporant of the evaporating material 9 quickly. It will change to. Note that when a reactive gas is used, the amount of reactive gas introduced into the chamber 11 increases as the amount of evaporation from the evaporation material 9 increases. Therefore, when the adhesion improving film 51 is an oxide film such as a metal oxide, the gas supply amount is controlled so as to show a time change as indicated by the reference symbol C.

  On the other hand, since the evaporation from the evaporating material 9 is promoted by the supply of electrons from the plasma, the current supplied to the boat 1 from the heating power source 3 by the feedback control based on the output of the film thickness monitor 17 is denoted by reference symbol B. Will decrease as shown. For this reason, the evaporation material 9 evaporates at a lower temperature than in normal vapor deposition or ion plating, and thus the substrate 50 may be excessively heated by the radiant heat from the evaporation source 20. Absent.

As described above, according to this embodiment, good plasma can be generated in the chamber 11 from the initial stage of the thin film formation by starting the thin film formation with the inert gas introduced into the chamber 11. . Thereby, the evaporation material is efficiently guided to the substrate 50 while receiving the action of plasma from the initial stage. As a result, it is selected from the group consisting of Cu, Cr, CrO, Cr ₂ O ₃ , Y ₂ O ₃ , La ₂ Ti ₃ O ₈ , SiO ₂ , TiO ₂ , and Al ₂ O ₃ with good adhesion. The thin film of the adhesion improving film 51 having at least one kind can be formed efficiently. When the adhesion improving film 51 is a multilayer film, a multilayer film having a desired number of layers is formed by repeating the above-described thin film forming operation.

After the formation of the adhesion improving film 51, the boat 1 or the crucible 26 of the evaporation source 20 accommodates and holds the silver alloy material as the evaporation material 9, and the adhesion on the substrate 50 is formed in the same manner as the formation of the adhesion improving film 51. A silver alloy layer is formed on the surface of the improvement film 51 to obtain the reflection film 52. At this time, an inert gas is supplied, but a reactive gas such as oxygen gas is not supplied. When obtaining a reflective film 52 of a dense silver alloy, the degree of vacuum in the chamber 11 is 1.0 × 10 ^{−3 to} 5.0 × 10 ⁻² Pa, preferably 5.0 × 10 ^{−3 to} 3.0 ×. 10 ⁻² Pa is preferable, and the formation rate of the reflective film 52 is 3 to 20 ３〜 / second, preferably 5 to 15 Å / second.

After the silver alloy reflective film 52 is formed, the reflection increasing film 53 is formed on the surface of the reflective film 52 in the same manner as the adhesion improving film 51 is formed. As the evaporation material 9 for forming the reflection increasing film 53, ZrO ₂ , Y ₂ O ₃ , MgF ₂ , LaTiO ₃ , La ₂ Ti ₃ O ₈ , SiO ₂ , TiO ₂ , or Al ₂ O ₃ is used. Can do. When the reflection increasing film 53 is formed into a multilayer having different film components, a thin film of these compounds is sequentially formed on the silver alloy reflecting film 52.

  When the intermediate film 54, the water repellent film 55, or both are formed as necessary, the boat 1 or the crucible 26 of the evaporation source 20 accommodates and holds the above compound as the evaporation material 9, and the adhesion improving film 51 is formed. The film is formed by an operation based on the formation of When these films are not metal oxides, oxygen gas which is a reactive gas is not supplied.

  For supplying each of the evaporating materials 9 to the boat 1 or the crucible 26, for example, the materials of the adhesion improving film 51, the reflecting film 52, and the reflection increasing film 53 are applied to the boat 1 from a coat material supplier (not shown). Alternatively, the films may be sequentially supplied, and evaporation may be sequentially performed under predetermined film forming conditions, so that the film is continuously formed on the surface of the substrate 50. When the intermediate film 54, the water repellent film 55, or both are formed, the films may be formed continuously in the order of formation.

  During the formation of these thin films, the substrate 50 is held at 70 ° C. or lower. Therefore, even if it is a resinous base material, the above-mentioned each film | membrane (layer) 51-55 can be favorably formed in the surface of a resinous base material, without receiving the influence of a deformation | transformation of the base material by a heat | fever. For example, the heat resistance temperature of polycarbonate is 120 to 130 ° C., and the heat resistance temperature of polymethyl methacrylate is about 80 ° C. Therefore, the respective films (layers) 51 to 55 are sequentially applied to the resin base material of these materials. It is possible to form a laminated layer satisfactorily.

  Thus, according to this thin film forming method, the gas for forming plasma is supplied into the chamber 11, so that plasma can be quickly generated in the chamber 11 at the initial stage of thin film formation. Thereby, it is possible to produce the respective films (layers) 51 to 55 using the action of plasma from the initial stage of thin film formation, and it is possible to obtain a reflecting mirror excellent in adhesion and durability. In addition, the amount of gas supplied into the chamber 11 is large at the initial stage of thin film formation and then reduced, so that the base material 50 is produced by the collision of the atoms and molecules of the inert gas supplied into the chamber 11 with the base material 50. Temperature rise can be suppressed.

  Further, positively charged particles or positively-charged particles in the plasma are accelerated toward the base material 50 by the direct current electric field applied from the direct current applied voltage power source 6, and collide with the base material 50. Deposited on the surface of the material 50. As a result, a film is formed. On the other hand, electrons having a negative charge are accelerated to the boat 1 on the anode side, intensively collide with the evaporation material 9 on the boat 1, and give the evaporation material 9 energy for evaporation. Thus, the evaporating material 9 that has obtained high energy instead of thermal energy easily evaporates even at a low temperature and evaporates into the plasma formation region in the chamber 11. That is, electrons in the plasma formed in the chamber 11 are guided to the evaporating material 9, thereby obtaining a so-called deposition assist effect that promotes evaporation of the material, so that the evaporating material 9 is heated by resistance heating or the like. Energy can be significantly reduced. As a result, since the temperature rise of the base material 50 can be suppressed, a thin film can be formed at a lower temperature.

  The amount of evaporation from the evaporating material 9 is adjusted by controlling the energy applied to the heating means and the output of the DC voltage application power source 6 within the above range. Moreover, the collision energy of the particles of the evaporation material 9 to the base material 50 is adjusted by controlling the output of the DC voltage application power source 6 within the above range. Thereby, the vapor deposition material is not simply deposited on the surface of the substrate 50 or the like, but has sufficient energy to rearrange the atomic or molecular arrangement of the vapor deposition material layer formed on the surface of the substrate 50 or the like in a stable state. Can be given. Furthermore, it is possible to give energy sufficient for the particles of the vapor deposition material to penetrate into the base material 50 or the like to be adapted.

  For this reason, in the present invention, the films 51 to 55 which are smooth and have almost no defects in the film, and which are dense and have excellent adhesion can be obtained. That is, in the silver alloy reflective film 52, a dense crystal structure is obtained, and the Ra value of the surface thereof is 2 nm or less, so that the adhesion with the reflection increasing film 53 or the intermediate film 54 is improved, and the periphery of the light reflector is improved. It is possible to highly prevent moisture from entering from the section. In addition, with respect to other films, since a film having a dense crystal structure is obtained, it is possible to highly prevent the penetration of moisture from the base material side and the reflection increasing film side.

  In the present invention, the shape of the substrate is not particularly limited. Therefore, for example, by using a resin base material 56 having a complicated shape as shown in FIG. 5, the multilayer films 57 including the above-described films 51 to 53 and 54 and 55 as necessary are directly formed on the surface. be able to. Further, the present invention is suitable for producing an aspherical mirror or the like.

Since the silver alloy reflective film in the present invention has good crystal orientation (aligned in one direction), it has the following advantages.
(1) The reflectance of light in a wide wavelength band (substantially visible light region) at a wavelength of 420 to 700 nm is as high as 97% or more.
(2) In the range where the incident angle of light is 10 to 50 °, the change in reflectance is as small as 0.5% or less.
(3) Excellent adhesion to resinous substrates and other films.
(4) Because of its excellent adhesiveness, coupled with the high corrosion resistance to moisture of the silver alloy itself, a leap of excellent durability that can maintain good reflectivity for a long time without causing deterioration such as whitening due to corrosion. The effect is effective.

  The light reflecting mirror of the present invention can be suitably used for various applications by utilizing its excellent characteristics. For example, it is suitable for mirror applications requiring high reflectivity such as a spherical or aspherical mirror such as a projector.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to a following example.

<Manufacture of light reflector>
1. Production Example 1
Using a polymethyl methacrylate resin (PMMA) plate having a thickness of 5 mm as a base material, each film (in order of the following (1) to (5) on the base material using the thin film forming apparatus shown in FIG. Layer) was directly laminated to produce a light reflector.
(1) Adhesion improving film 51: Two layers of chromium (Cr) (thickness 20 nm) and copper (Cu) (thickness 60 nm) were laminated in this order.
(2) Reflective film 52: Silver-bismuth (Ag-Bi) alloy (“Ag-1.0 at% Bi alloy (bismuth: 1.9 wt%)” manufactured by Kobelco Research Institute, Inc.) (thickness 120 nm) on the Cu film Laminated.
(3) Intermediate film 54: Aluminum oxide (Al ₂ O ₃ ) (thickness 54 nm) was laminated on the Ag—Bi film.
(4) Reflection increasing film 53: 4 of zirconium dioxide (ZrO ₂ ) (thickness 15 nm), silicon dioxide (SiO ₂ ) (thickness 15 nm), ZrO ₂ (thickness 20 nm), and SiO ₂ (thickness 15 nm) The layers were laminated on the Al ₂ O ₃ film in this order.
(5) Water-repellent film: A MERCK Substance WR1 Pattern (trademark) (fluorine silicon compound) (thickness 20 nm) was laminated on the SiO ₂ film.
The conditions for forming each layer are as follows.

(1) Adhesion improving film 51
Evaporating material 9: Cr, Cu (First, after forming the Cr film by the following operation, the Cu film was formed on the Cr film by the same operation)
Gas introduced into the chamber 11: Argon gas High frequency power supply power applied from the power supply 5 to the base material holding unit 2: 31.6 mW / cm ² at a frequency of 13.56 MHz (application per unit area of the base material holding unit 2 Power)
DC application power source 6: The cathode side is connected to the base material holding part 2, and the anode side is connected to the boat 1. Applied voltage from the DC application power source 6 to the base material holding part 2: 200V
Chamber 11: Electrically floating state adhesion improving film not grounded Rate of formation: 3 Å / sec (Cr), 6 Å / sec (Cu)
(A) Initial stage of adhesion improving film formation (t10 to T2 in FIG. 4)
Degree of vacuum in the chamber 11: 1.5 × 10 ⁻³ Pa or less (at t10)
Energizing current from the heating power source 3 to the boat 1: 280 A (T2 end)
(B) Adhesion improving film forming stage (T3 in FIG. 4)
Degree of vacuum in the chamber 11: 1.5 × 10 ⁻² Pa or less Current flowing from the heating power source 3 to the boat 1: 210 A (T3 end)
In this way, a two-layer adhesion improving film composed of a 20 nm thick Cr film and a 60 nm thick Cu film was formed on the substrate 50. The temperature of the base material 50 was kept at about 40 to 45 ° C. throughout the entire period of the adhesion improving film formation because the thermo seal that reacted at 40 ° C. reacted slightly.

(2) Reflective film 52
Evaporating material 9: Ag-Bi
Gas introduced into the chamber 11: Argon gas High frequency power supply power applied from the power supply 5 to the base material holding unit 2: 31.6 mW / cm ² at a frequency of 13.56 MHz (application per unit area of the base material holding unit 2 Power)
DC application power source 6: The cathode side is connected to the base material holding part 2, and the anode side is connected to the boat 1. Applied voltage from the DC application power source 6 to the base material holding part 2: 200V
Chamber 11: Formation rate of electrically floating reflective film not grounded: 10 Å / sec (a) Initial stage of reflective film formation (t10 to T2 in FIG. 4)
Degree of vacuum in the chamber 11: 1.5 × 10 ⁻³ Pa or less (at t10)
Energizing current from the heating power source 3 to the boat 1: 280 A (T2 end)
(B) Reflective film formation stage (T3 in FIG. 4)
Degree of vacuum in the chamber 11: 1.5 × 10 ⁻² Pa or less Current flowing from the heating power source 3 to the boat 1: 210 A (T3 end)
In this way, an Ag—Bi alloy film having a thickness of 120 nm was formed on the Cu film. The temperature of the base material 50 was maintained at about 40 to 45 ° C. throughout the entire period of the formation of the reflective film because the thermo seal that reacted at 40 ° C. reacted slightly.

(3) Intermediate film 54
Evaporating material 9: Al ₂ O ₃
Gas introduced into the chamber 11: Oxygen gas RF power supply power supply 5 applied to the base material holding unit 2: 52.6 mW / cm ² at a frequency of 13.56 MHz (applied per unit area of the base material holding unit 2 Power)
DC application power source 6: The cathode side is connected to the base material holding part 2, and the anode side is connected to the boat 1. Applied voltage from the DC application power source 6 to the base material holding part 2: 200V
Chamber 11: Formation rate of electrically floating intermediate film that is not grounded: 4 Å / sec (a) Initial stage of intermediate film formation (t10 to T2 in FIG. 4)
Degree of vacuum in the chamber 11: 1.5 × 10 ⁻³ Pa or less (at t10)
Energizing current from the heating power source 3 to the boat 1: 350 A (T2 end)
(B) Intermediate film formation stage (T3 in FIG. 4)
Degree of vacuum in the chamber 11: 1.5 × 10 ⁻² Pa or less Current flowing from the heating power source 3 to the boat 1: 230 A (T3 end)
In this way, an Al ₂ O ₃ film having a thickness of 54 nm was formed on the Ag—Bi alloy film. The temperature of the substrate 50 was kept below 40 ° C. throughout the entire period of forming the intermediate film.

(4) Reflection increasing film 53
Evaporating material 9: ZrO ₂ , SiO ₂ , ZrO ₂ , SiO ₂ (formed in this order)
Gas introduced into the chamber 11: Applied power from the oxygen gas high-frequency power supply 5 to the base material holder 2: 52.6 (at the time of SiO ₂ film formation) or 79 (ZrO ₂ film formation at a frequency of 13.56 MHz) Hour) mW / cm ² (applied electric power per unit area of the substrate holder 2)
DC application power source 6: The cathode side is connected to the substrate holding unit 2 and the anode side is connected to the boat 1. Applied voltages from the DC application power source 6 to the substrate holding unit 2: 200V (SiO ₂ ), 300V (ZrO ₂ )
Chamber 11: Formation rate of an electrically floating reflection increasing film that is not grounded: 7 Å / sec (SiO ₂ ), 2 Å / sec (ZrO ₂ )
(A) Initial stage of reflection increasing film formation (t10 to T2 in FIG. 4)
Degree of vacuum in the chamber 11: 1.5 × 10 ⁻³ Pa or less (at t10)
Energizing current from the heating power source 3 to the boat 1: 350 A (T2 end)
(B) Reflection increasing film formation stage (T3 in FIG. 4)
Degree of vacuum in the chamber 11: 1.5 × 10 ⁻² Pa or less Current flowing from the heating power source 3 to the boat 1: 230 A (T3 end)
In this way, a four-layer reflection increasing film composed of a ZrO ₂ film (thickness 15 nm), a SiO ₂ film (thickness 15 nm), a ZrO ₂ film (thickness 20 nm), and a SiO ₂ film (thickness 15 nm) is formed. And formed on an Al ₂ O ₃ film. The temperature of the base material 50 was kept below 40 ° C. throughout the entire period of forming the reflection increasing film.

(5) Water repellent film 55
Evaporating material 9: MERCK Substance WR1 Patinal (trademark)
Gas introduced into the chamber 11: Formation speed of the non-water-repellent film: 7 Å / sec Since the introduced gas is not used when forming the water-repellent film, the gas supply amount corresponding to FIG. Yes, the degree of vacuum in the chamber 11 corresponding to FIG. 4B is 5.0 × 10 ⁻² Pa or less for the entire period.
(A) Initial stage of water repellent film formation (corresponding to t10 to T2 in FIG. 4)
Energizing current from the heating power source 3 to the boat 1: 350 A (T2 end)
(B) Water repellent film formation stage (corresponding to T3 in FIG. 4)
Energizing current from the heating power source 3 to the boat 1: 230 A (T3 end)
In this way, the water repellent film having a thickness of 20 nm was formed on the outermost SiO ₂ film of the reflection increasing film. The temperature of the base material 50 was kept below 40 ° C. throughout the entire period of forming the water repellent film.

2. Production Example 2
A polycarbonate (PC) plate having a thickness of 5 mm is used as a base material, and each film (layer) is directly applied on the base material in the order of (1) to (4) below using the thin film forming apparatus shown in FIG. Laminated to produce a light reflector.
(1) Adhesion improving film 51: Two layers of chromium (Cr) (thickness 20 nm) and copper (Cu) (thickness 60 nm) were laminated in this order.
(2) Reflective film 52: A silver-bismuth (Ag-Bi) alloy (same as in Production Example 1) (thickness 120 nm) was laminated on the Cu film.
(3) Intermediate film 54: Magnesium fluoride (MgF ₂ ) (thickness 74 nm) was laminated on the Ag—Bi film.
(4) Reflection increasing film 53: 4 of zirconium dioxide (ZrO ₂ ) (thickness 15 nm), silicon dioxide (SiO ₂ ) (thickness 15 nm), ZrO ₂ (thickness 20 nm), and SiO ₂ (thickness 15 nm) The layers were laminated on the MgF ₂ film in this order.

The (1) adhesion improving film 51, (2) the reflecting film 52, and (4) the reflection increasing film 53 were formed in the same manner as in Production Example 1.

(3) Intermediate film 54
Evaporation material 9: MgF ₂
Gas introduced into the chamber 11: Argon gas High frequency power supply power applied to the base material holder 2 from the power supply 5: 52.6 mW / cm ² at a frequency of 13.56 MHz (applied per unit area of the base material holder 2 Power)
DC application power source 6: The cathode side is connected to the base material holding part 2, and the anode side is connected to the boat 1. Applied voltage from the DC application power source 6 to the base material holding part 2: 250V
Chamber 11: Formation speed of electrically floating intermediate film not grounded: 8 Å / sec (a) Initial stage of intermediate film formation (t10 to T2 in FIG. 4)
Degree of vacuum in the chamber 11: 1.5 × 10 ⁻³ Pa or less (at t10)
Energizing current from the heating power source 3 to the boat 1: 350 A (T2 end)
(B) Intermediate film formation stage (T3 in FIG. 4)
Degree of vacuum in the chamber 11: 1.5 × 10 ⁻² Pa or less Current flowing from the heating power source 3 to the boat 1: 230 A (T3 end)
In this manner, MgF ₂ having a thickness of 74 nm was formed on the Ag—Bi alloy film. The temperature of the substrate 50 was kept below 40 ° C. throughout the entire period of forming the intermediate film.

3. Comparative production example 1
In order to obtain a silver reflective film, each film was formed under the same conditions as in Production Example 1 except that the evaporation material 9 was silver (Ag) in the formation of the reflective film 52 to produce a light reflecting mirror.

  The following evaluation tests were performed on the light reflecting mirrors manufactured in Manufacturing Examples 1 and 2 and Comparative Manufacturing Example 1. In addition, the surface roughness and the (111) peak intensity by X-ray diffraction of the reflective film 52 are the same until the reflective film 52 is formed in each production example, and a film whose film formation is completed at that stage is prepared. And measured. Further, the filling density of the intermediate film 54 was measured by preparing a film in which only the intermediate film was formed on the glass plate under the same conditions as the intermediate film forming conditions of Production Example 1.

<Evaluation test>
1. Surface roughness of the reflective film 52 The surface states of the Ag-Bi alloy film formed in Production Examples 1 and 2 and the Ag film formed in Comparative Production Example 1 were measured using an atomic force microscope (AFM, Nano Scope manufactured by Digital Instruments). II), the irregularities on the film surface were imaged on the nanometer order, and the arithmetic average roughness (Ra) was examined from this.

2. X-ray diffractometer (RINT1400V manufactured by Rigaku Corporation ) for the Ag-Bi alloy film formed in (111) peak intensity production examples 1 and 2 and the Ag film formed in comparative production example 1 by X-ray diffraction of the reflective film 52 Type), X-ray output 50 kV-200 mA, measurement range 2θ = 10 ° -100 °, light emitting slit-scattering slit-light receiving slit: 1 ° -1 ° -0.3 mm.

3. Filling density of the intermediate film 54 Under the same conditions as the intermediate film forming conditions of Production Example 1, only the intermediate film was formed on the glass plate, and the packing density of the Al ₂ O ₃ intermediate film was measured by a moisture resistance test. That is, in this measurement method, a metal oxide film is left for 24 hours in an environment of a temperature of 60 ° C. and a humidity of 90%, the change in reflectance is measured before and after being left, and the refractive index is calculated from the change in reflectance. It seeks change. The smaller the change in refractive index, the greater the packing density. For example, when a glass plate having a refractive index ns is coated, the reflectance R is expressed by the following equation.

ただし、ｎｆ:金属酸化膜の屈折率、
δ＝（２π／λ）ｎｆ・ｄｃｏｓθ、
λ：光波長、
ｄ：金属酸化膜の厚さ、
θ：光の入射角
このＲの測定ピーク値から式：ｎｆ^２＝ｎｓ（１＋Ｒ^１／２）／（１−Ｒ^１／２）によってｎｆの測定値が求められる。一方、充填密度Ｐに関する金属酸化膜の屈折率は次式で表される。

Where nf: refractive index of the metal oxide film,
δ = (2π / λ) nf · d cos θ,
λ: optical wavelength,
d: thickness of the metal oxide film,
θ: incident angle of light From this measured peak value of R, the measured value of nf is obtained by the formula: nf ² = ns (1 + R ^1/2 ) / (1−R ^1/2 ). On the other hand, the refractive index of the metal oxide film with respect to the packing density P is expressed by the following equation.

ただし、ｎｍ：金属酸化膜の実体部分の屈折率、
ｎｖ：気孔内の水蒸気の屈折率で１．３３
このｎｆの測定値と充填密度Ｐに関する屈折率（理論値）の差からＰを求める。
例えば、Ｐを１.００、０．９９、０．９８等と変化させて、式：ｎｆ＝Ｐｎｍ＋（１−Ｐ ）ｎｖに代入していき、この理論値と測定値が一致したときのＰを金属酸化膜の充填密度として特定することによって求められる。測定の結果、反射率の変化が０．２％以内であったため、充填密度は０．９８以上、より正確には０．９９以上と判断される。

Where nm is the refractive index of the substantial part of the metal oxide film,
nv: 1.33 in refractive index of water vapor in the pores
P is obtained from the difference between the measured value of nf and the refractive index (theoretical value) regarding the packing density P.
For example, P is changed to 1.00, 0.99, 0.98, etc., and is substituted into the formula: nf = Pnm + (1-P) nv, and P when the theoretical value and the measured value coincide with each other is calculated. Is determined as the packing density of the metal oxide film. As a result of the measurement, since the change in reflectance was within 0.2%, it is determined that the packing density is 0.98 or more, more precisely 0.99 or more.

4). Reflectivity in the visible light region (420 to 690 nm) before the durability test described below for the light reflecting mirrors manufactured in the reflectance manufacturing examples 1 and 2 and comparative manufacturing example 1 in the visible light region. Measured with a spectrophotometer U-4000 manufactured by Hitachi, Ltd. Moreover, it measured about the light reflection mirror in the state which can be measured after a durability test.

5. Durability test 1 (salt spray test)
Only the installation angles of the test pieces (light reflecting mirrors according to the respective production examples) were as follows, and the others were subjected to a salt spray test in accordance with JIS Z2371. After spraying salt water for 24 hours under the following conditions, the appearance of each test piece was observed and evaluated.
(1) Test temperature: 35 ° C ± 2 ° C
(2) Spray solution: 5% neutral saline (pH 6.5 to 7.2)
(3) Spray amount: 1 to ² mL / 80 cm ² / h
(4) Salt: Special grade sodium chloride specified in JIS K8150 (5) Angle of test piece: 45 ° with respect to vertical surface, membrane coating surface facing downward

6). Durability test 2 (salt water immersion test)
For the light reflectors produced in Production Examples 1 and 2 and Comparative Production Example 1, a commercially available 3% aqueous solution of industrial salt was prepared, and an immersion test in the 3% aqueous salt solution was performed. The room temperature of the test room was 25 ° C. and the humidity was 27%. Each light reflecting mirror was immersed in the salt water and taken out every hour to observe the appearance. Further, for the light reflecting mirrors of Production Examples 1 and 2, the reflectance in the visible light region after 48 hours of immersion was measured in the same manner as described above.

<Evaluation results>
Table 1 shows the results of the above evaluation tests for the light reflecting mirrors manufactured in the respective manufacturing examples. As is apparent from the table, the light reflecting mirrors according to Production Examples 1 and 2 are significantly superior in durability compared to those according to Comparative Production Example 1.

The light reflecting mirror of the present invention can be suitably used for various applications as exemplified below by utilizing its excellent characteristics.
A. Reflector for projector equipment.
B. A light tunnel for a DLP projector (an optical component in which a silver film and a transparent dielectric layer are formed on the inner surface of a rectangular tube-shaped substrate).
C. Reflectors such as astronomical telescopes and binoculars.
D. An alternative to reflectors that use aluminum reflective layers in various optical devices.
E. Since a resin base material can be used, a highly reflective deformed mirror in which a deformed resin base material with predetermined irregularities formed on the surface by coating with a reflective film is used.

1: boat, 2: base material holding unit, 3: heating power source, 4: matching device, 5: high-frequency power supply power source, 6: DC voltage application power source, 7: capacitor, 8: coil, 9: evaporation material, 10: Substrate, 11: chamber, 12: exhaust duct, 13: exhaust valve, 14: vacuum pump, 15: vacuum gauge, 17: film thickness monitor, 18: shutter, 20: evaporation source, 21: inert gas supply source , 23: reactive gas supply source, 24: flow rate control device, 25: gas supply piping, 26: crucible, 27: electron gun, 50: substrate, 51: adhesion improving film, 52: reflection film, 53: reflection Increase film, 54: intermediate film, 55: water repellent film, 56: resin base material, 57: multilayer film

Claims (10)

  Light reflection, having an adhesion improving film, a silver alloy reflective film, and a reflection increasing film on the surface of the substrate, and the Ra value of the surface of the reflective film on the side in contact with the reflection increasing film being 2 nm or less mirror.   The light reflecting mirror according to claim 1, wherein the reflective film is a silver alloy having bismuth.   The light reflecting mirror according to claim 1 or 2, wherein the base material is one of glass, a thermoplastic resin, a thermosetting resin, an infrared transmitting metal, aluminum, carbon steel, or alloy steel.   4. The reflective film according to claim 1, wherein the (111) peak intensity by X-ray diffraction of the surface on the side where the Ra value is 2 nm or less is 20 times or more of the total of other peak intensities. Light reflector. The adhesion improving film is at least one selected from the group consisting of Cu, Cr, CrO, Cr ₂ O ₃ , Y ₂ O ₃ , La ₂ Ti ₃ O ₈ , SiO ₂ , TiO ₂ , and Al ₂ O _3. The light-reflecting mirror according to claim 1, wherein the adhesion improving film is a single layer or a multilayer film of four layers or less. The reflection increasing film is at least one selected from the group consisting of ZrO ₂ , Y ₂ O ₃ , MgF ₂ , LaTiO ₃ , La ₂ Ti ₃ O ₈ , SiO ₂ , TiO ₂ , and Al ₂ O ₃ . The light reflection mirror according to claim 1, wherein the reflection increasing film is a single layer or a multilayer film of five layers or less. The intermediate film selected from Y ₂ O ₃ , MgF ₂ , Al ₂ O _3, or SiO ₂ is provided between the silver alloy reflective film and the reflection increasing film according to claim 1. The light reflector described.   The light reflecting mirror according to any one of claims 1 to 7, wherein a water repellent film having a thickness of 15 to 40 nm is provided on an uppermost layer of each of the films formed on the surface of the base material. Forming the adhesion improving film on the substrate surface;
Forming a reflective film of the silver alloy;
Forming the reflection enhancing film,
All these steps are performed in succession,
During all the steps, the temperature of the substrate is kept below 70 ° C.
The method to manufacture the light reflection mirror as described in any one of Claims 1-8. Forming the adhesion improving film on the substrate surface;
Forming a reflective film of the silver alloy;
Forming the intermediate film;
Forming the reflection enhancing film,
All these steps are performed in succession,
During all the steps, the temperature of the substrate is kept below 70 ° C.
The method to manufacture the light reflection mirror as described in any one of Claims 1-8.

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