JP5162271B2 - Glass member with optical multilayer film and method for producing the same - Google Patents

Description

  The present invention relates to a glass member with an optical multilayer film and a method for producing the same.

  For solid-state image sensors such as CCDs and CMOSs used in digital still cameras and video cameras, various kinds of color correction such as visibility correction, infrared cut, antireflection for light quantity attenuation and stray light suppression The optical multilayer film is used. As an optical multilayer film, a film in which a high refractive index film made of titanium oxide, tantalum oxide, niobium oxide or the like and a low refractive index film made of silicon oxide or the like are alternately laminated on a glass substrate is known. The optical multilayer film selectively transmits or blocks light based on the thickness, the number of layers, and the like of the high refractive index film and the low refractive index layer.

  A vapor deposition method is generally used to form an optical multilayer film on a glass substrate. When an optical multilayer film is formed by applying a vapor deposition method, tensile stress is generated in the optical multilayer film based on the substrate temperature at the time of film formation, etc., thereby causing cracks in the optical multilayer film and further causing film breakdown. May occur. For such a point, a silicon oxide film having a compressive stress is interposed between the glass substrate and the optical multilayer film, and the tensile stress of the optical multilayer film is weakened by the compressive stress of the silicon oxide film. It has been proposed to suppress cracks and breakage (see Patent Documents 1 and 2).

The optical multilayer film formed by the vapor deposition method has problems that a change in characteristics such as a film stress change and a spectral change with time is large, and that the hardness is low and the film is easily scratched. On the other hand, an optical multilayer film formed by applying a sputtering method has an advantage that a non-shift film having substantially no spectral change can be realized with very little change in spectral characteristics under high temperature and high humidity. The optical multilayer film formed by sputtering is hard to be scratched due to its high hardness, is easy to handle in the component assembly process, and has a small change in film stress and stable mechanical strength characteristics.
Japanese Patent Laid-Open No. 60-6905 JP 2003-114327 A

  The optical multilayer film formed by sputtering has compressive internal stress (true stress), and since the film quality is hard, the optical properties and mechanical properties are stable, and the handling properties are excellent. On the other hand, there is a problem that film cracking or film peeling is likely to occur in the manufacturing process of an optical component with an optical multilayer film, particularly in the cutting process. Occurrence of film cracks or film peeling in the cutting process or the like becomes a factor of deteriorating the characteristics and quality of the optical component.

  For example, when trying to cut a glass substrate having an optical multilayer film formed by a sputtering method, since the film quality of the optical multilayer film (sputtered film) is dense and hard, fine cracks generated on the cut surface extend, which is the starting point. Film peeling may occur. Furthermore, since the optical multilayer film (sputtered film) has a high film stress, this stress promotes the phenomenon from crack extension to film peeling, and the film stress itself peels off between the glass substrate and the optical multilayer film. There is also a risk of working as a force to generate. As described above, the film stress and film quality of the optical multilayer film (sputtered film) contribute to the improvement of the characteristics, but on the contrary, it causes film cracking and film peeling at the time of cutting.

  An object of the present invention is to suppress the occurrence of film cracking or film peeling at the time of cutting an optical multilayer film having a compressive stress by a sputtering method or the like, and to improve characteristics, quality, reliability, etc. It is providing the glass member with a film | membrane and its manufacturing method.

An optical multilayer film-attached glass member according to an aspect of the present invention is provided with an optical multilayer film comprising a glass substrate and an optical multilayer film that is formed on the main surface of the glass substrate via an adhesion strengthening layer and has a compressive stress. A glass member, wherein the adhesion enhancement layer is a sputtered film formed in a transition state in reactive sputtering, has a film thickness of 50 nm or more, has a compressive stress, and has a stoichiometric bias. It is characterized in that it consists of a silicon oxide film produced.

The method for producing a glass member with an optical multilayer film according to an aspect of the present invention uses a transition state in reactive sputtering on a main surface of a glass substrate having a substrate temperature of less than 80 ° C. at the start of film formation. optical but having at 50nm or more and which has a compressive stress, a step of stoichiometric bias sputter deposited adhesion reinforcing layer formed of silicon oxide film produced, the compressive stress on the adhesion reinforcing layer And a step of forming a multilayer film.

  According to the glass member with an optical multilayer film and the method for producing the same according to the aspect of the present invention, film cracks and film peeling of the optical multilayer film can be suppressed. Therefore, it is possible to provide a glass member with an optical multilayer film excellent in characteristics, quality, reliability and the like with good reproducibility.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of a glass member with an optical multilayer film according to an embodiment of the present invention. A glass member 1 with an optical multilayer film shown in FIG. 1 includes a glass substrate 2 and an optical multilayer film 4 formed on a main surface 2a of the glass substrate 2 with an adhesion strengthening layer 3 interposed therebetween. In such a glass member 1 with an optical multilayer film, the adhesion strengthening layer 3 improves the adhesion between the glass substrate 2 and the optical multilayer film 4 and suppresses the occurrence of film cracks and film peeling.

  The optical multilayer film 4 is appropriately selected according to the application. For example, an antireflection film having an antireflection function (AR film: Anti Reflection film), an infrared cut film (an ultraviolet ray having a cut function also in an ultraviolet wavelength region). -Including an infrared cut film), an infrared transmission film, a dichroic film, and the like. For the optical multilayer film 4 having such a function, for example, a laminated film in which low refractive index films and high refractive index films are alternately arranged is used. A silicon oxide film or the like is used as the low refractive index film. As the high refractive index film, a metal oxide film made of at least one selected from niobium oxide, titanium oxide, and tantalum oxide is used. The film thickness and the number of stacked layers of the low refractive index film and the high refractive index film are appropriately set according to the required optical characteristics.

  The optical multilayer film 4 has a compressive stress as an internal stress (true stress). The optical multilayer film 4 having a compressive stress is dense and can greatly suppress changes in spectral characteristics. Furthermore, a non-shift film having substantially no spectral change can be used. By these, the weather resistance, reliability, durability, etc. of the optical multilayer film 4 can be improved. Further, the dense optical multilayer film 4 has a high film hardness and can suppress the occurrence of scratches during handling. Also from this point, the reliability and durability of the optical multilayer film 4 can be improved.

  The optical multilayer film 4 having a compressive stress can be obtained, for example, by forming a low refractive index film or a high refractive index film by a sputtering method. According to the sputtering method, the formed film (sputtered film) becomes dense, so that compressive stress is generated inside the film. The optical multilayer film 4 is particularly preferably formed by utilizing a transition state in reactive sputtering. A film forming method using a transition state in reactive sputtering will be described in detail later. Note that the method for forming the optical multilayer film 4 having compressive stress is not limited to the sputtering method, and vapor deposition using ion assist capable of forming a dense film is applied as in the case of sputtering. It is also possible. Also by such a film forming method, the optical multilayer film 4 having a compressive stress can be obtained.

The glass substrate 2 on which the optical multilayer film 4 is formed preferably has a thermal expansion coefficient in the range of 5 to 100 × 10 ⁻⁷ / ° C. (0 to 300 ° C.). Furthermore, it is desirable that the glass substrate 2 has a thermal expansion coefficient larger than that of the adhesion strengthening layer 3. By using the glass substrate 2 having such a thermal expansion coefficient, it is possible to more effectively obtain the effect of suppressing film cracks and film peeling by the adhesion reinforcing layer 3 as will be described in detail later. In order to make the thermal expansion coefficient of the glass substrate 2 in the range of 5 to 100 × 10 ⁻⁷ / ° C., the glass substrate 2 is preferably composed of silicate glass or phosphate glass.

  When the optical multilayer film 4 having a compressive stress is directly formed on the main surface 2a of the glass substrate 2, film cracks, film peeling, etc. are likely to occur in the optical component manufacturing process. In particular, there is a high possibility that fine cracks generated on the cut surface in the cutting process are elongated, and this causes the film to peel off. Therefore, in this embodiment, an adhesion strengthening layer 3 made of a silicon oxide film having a thickness of 50 nm or more and having a compressive stress is interposed between the glass substrate 2 and the optical multilayer film 4. Since the silicon oxide film is made of an oxide of silicon (Si) that can form a glass network, the silicon oxide film has high affinity for the glass substrate 2 and exhibits good adhesion and adhesion. Furthermore, since the silicon oxide film is transparent and has little influence on the optical characteristics, it is effective as the adhesion enhancing layer 3 of the optical multilayer film 4.

  In this embodiment, a silicon oxide film having a compressive stress is used as the adhesion strengthening layer 3. Since the adhesion strengthening layer 3 having compressive stress does not adversely affect the characteristics of the optical multilayer film 4 as a non-shift film or the like, the occurrence of film cracking or film peeling of the optical multilayer film 4 is suppressed, and compression is performed. It is possible to maintain excellent characteristics of the optical multilayer film 4 having stress. When the adhesion strengthening layer 3 has a tensile stress, the original function of the adhesion strengthening layer 3 is impaired, for example, film peeling easily occurs between the glass substrate 2 and the adhesion strengthening layer 3.

As a method for forming the adhesion strengthening layer 3, for example, a sputtering method is used. As described above, a film having a compressive stress can be obtained by the sputtering method. The adhesion strengthening layer 3 is preferably formed using a transition state in reactive sputtering. Reactive sputtering is a material that is made to collide with ions (Ar ⁺ ions, etc.) in a sputtering gas (argon gas, etc.) against a metal target that is a raw material for the compound film, and is ejected from the metal target based on the collision energy. This is a method in which atoms (sputtered particles) are reacted with a reactive gas (oxygen gas or the like) and deposited as a compound film (oxide film or the like) on a deposition target substrate.

  In reactive sputtering, the energy of sputtered particles is high, and the compound film is deposited on the deposition target substrate with high activity. Therefore, by forming a silicon oxide film by reactive sputtering as the adhesion enhancing layer 3, the adhesion enhancing layer 3 having excellent adhesion with the glass substrate 2 can be obtained. Furthermore, in reactive sputtering, there are several states with different film formation rates and film qualities. Generally, there are three states called a metal state, a transition state, and a compound state. The adhesion strengthening layer 3 made of a silicon oxide film is preferably formed using a transition state in reactive sputtering.

  FIG. 2 schematically shows the relationship between the amount of reactive gas introduced in reactive sputtering and the film formation rate. An outline of each of these states will be described. The metal state exists when the amount of reactive gas is relatively small, and the state is stable. Since the deposition rate is very high, the metal target surface is not contaminated by the reactive gas. The formed film is an incomplete compound film and exhibits metallic properties. The compound state exists when the reactive gas is relatively large, and the state is stable. In this state, since there are many reactive gases, the surface of the metal target reacts with the reactive gas and is covered with a compound film, that is, the same as when a metal oxide target is used. Therefore, the film formation rate is very low, but the formed film is completely compounded.

  In the transition state, the reactive gas is approximately between the metal state and the compound state, and the state is very unstable. The film formation rate is relatively fast, and the film quality obtained varies depending on the conditions, from a fully combined film to an incompletely combined film. In addition, regarding these phenomena, model consideration by Berg et al. (S. Berg, H.O. Blom, T. Larsson, C. Nender: J. Vac, Sci. Technol. A, 5, (1987), 202) and Haruhiro Kobayashi “Sputtered Thin Film” (Nikkan Kogyo Shimbun).

  The transition state in reactive sputtering will be described in detail. As shown in FIG. 2, when the amount of oxygen introduced is increased stepwise from the metal state, the film formation rate rapidly decreases near the inflection point (indicated by a downward arrow), and oxidation hysteresis (history phenomenon) occurs. Arise. This is because, even when the amount of oxygen introduced is gradually reduced from the compound state, the film formation rate increases rapidly in the direction of the upward arrow in the vicinity of the inflection point. However, by precisely controlling the oxygen introduction amount, it is possible to obtain a transition state as shown in the characteristic curve without causing a sudden state change.

  The transition state will be described using a characteristic curve. This is a region where the state changes greatly with respect to the amount of oxygen introduced. Specifically, the inflection point on the compound state side (boundary between the compound state and the transition state) and the inflection point on the metal state side (metal state) in the characteristic curves of film formation rate—oxygen introduction amount and plasma emission intensity—oxygen introduction amount And the boundary between transition states). Note that, depending on the sputtering apparatus and the target material, the bending point may not be clear in the characteristic curve of plasma emission intensity-oxygen gas introduction amount. In this case, it can be said that a transition state is similarly obtained at a bending point appearing in a characteristic curve of the sputtering voltage-oxygen gas introduction amount.

  When forming the adhesion strengthening layer 3 made of a silicon oxide film by reactive sputtering, the film formation state is controlled to a transition state based on the amount of oxygen introduced, etc. As a result, a mixed state with the formed film is obtained. In this way, the state at the time of formation of the adhesion strengthening layer 3 is controlled to a transition state, and the silicon oxide constituting the adhesion strengthening layer 3 is caused to be stoichiometrically biased to be oxidized in a more active state. Silicon can be deposited on the glass substrate 1. Accordingly, it is possible to further improve the adhesion between the adhesion reinforcing layer 3 and the glass substrate 2.

  The transition state in reactive sputtering is unstable, and in FIG. 2, the transition from the inflection point of the inverted S-curve cannot be changed to the transition state, and the compound state is changed to the metal state or the metal state to the compound state (direction indicated by the arrow). As a result, hysteresis is formed in reactive sputtering. In order to stably control such an unstable transition state, the plasma emission intensity of a specific wavelength in the plasma of reactive sputtering is monitored, and the amount of oxygen gas introduced so that the plasma emission intensity becomes a constant value is monitored. It is preferable to use a transition control technique such as so-called plasma emission monitoring.

  FIG. 3 shows an outline of the configuration of the reactive sputtering apparatus when plasma emission monitoring is used. The reactive sputtering apparatus 10 includes a target (Si target) 12 and a deposition target substrate (glass substrate) 13 that are disposed facing each other in a chamber 11. In FIG. 3, P is a plasma sheath. In the reactive sputtering apparatus 10, the light emission of the plasma P is received by the optical fiber 14, guided outside the chamber 11, and received by the photomultiplier 16 via a band pass filter (BPF) 15 for selecting a specific wavelength. The The light intensity received by the photomultiplier 16 is converted into an electric signal, and the data is integrated by the light quantity integrator 17 and averaged in an appropriate form. This data is sent to an arithmetic processing unit 18 such as a personal computer to determine the amount of reactive gas introduced.

  Based on the determined reactive gas introduction amount data, the mass flow controller 19 is driven to control the reactive gas amount introduced into the chamber 11. By using these devices, it is possible to more stably control a transition state that is extremely unstable as a state. And the adhesiveness of the glass substrate 2 and the adhesive reinforcement layer 3 can be improved by forming the adhesive reinforcement layer 3 in a transition state. When using reactive sputtering plasma emission monitoring to form an Si oxide film with Si as the target, the plasma emission intensity during the formation of the adhesion enhancing layer 3 is the plasma emission intensity in the oxidized state (100%). It is preferable to control in the range of 5 to 40%.

  In addition to having a compressive stress, the adhesion strengthening layer 3 made of a silicon oxide film is important to have a thickness of 50 nm or more. Since the adhesion strengthening layer 3 made of a silicon oxide film has a compressive stress and a film thickness of 50 nm or more, it becomes possible to suppress film cracking and film peeling when the optical multilayer film 4 having compressive stress is cut. . When the film thickness of the adhesion strengthening layer 3 is less than 50 nm, it is not possible to sufficiently obtain the effect of suppressing the film peeling or the like based on the relaxation of the compressive stress and the movement of the stress concentration point from the vicinity of the interface described below. The film peeling suppression action of the adhesion strengthening layer 3 having a compressive stress and a film thickness of 50 nm or more will be described in detail below.

  As described above, the silicon oxide film (adhesion-strengthening layer 3) formed by using a reactive sputtering method, particularly a transition state in reactive sputtering, exhibits good adhesion to the glass substrate 2. However, as a result of many studies and tests conducted by the present inventors, it has been found that even when such a sputtering method is applied, film peeling may occur. It has been clarified that this phenomenon occurs in various glass substrates such as silicate glass, phosphate glass, and fluorophosphate glass. As conditions for such film peeling to occur on various glass substrates, it can be considered that the surface of the glass substrate itself is weakened for some reason.

  According to the examinations and tests by the present inventors, it was found that the glass substrate was often found particularly after a cleaning process using an alkali cleaning agent. The alkaline cleaning agent here is a cleaning agent containing an alkaline component such as NaOH or KOH in the cleaning agent, and the cleaning solution using this cleaning agent has a pH of 8 or more, generally 10 or more. It is. Such a cleaning process using an alkali cleaning agent often exhibits excellent cleaning ability for a glass substrate, and is generally used for imaging-related substrate cleaning in which appearance and optical characteristics are particularly important.

  According to the tests by the present inventors, alkali cleaning alters the surface state of a glass substrate containing an alkali metal component or a phosphoric acid-based glass substrate at the composition level, and this is extremely likely to cause film peeling. It is considered to be in a state. The alteration phenomenon at the composition level of the glass substrate surface is considered to be caused directly by the elution of the glass components into the cleaning liquid. A phenomenon may occur. In other words, the deterioration and weakness of the surface condition of the glass substrate is essentially a problem, and the same applies when the surface of the glass substrate is deteriorated or weakened even for causes other than the alkali cleaning process. The phenomenon is thought to occur.

  It is conceivable that the surface layer (fragile layer) is removed by physical etching (reverse sputtering or the like) for alteration or weakening of the glass substrate surface. However, the physical etching process is not only complicated in apparatus, but also difficult to introduce in a carousel type sputtering apparatus or the like, and in some cases, the process itself may become a source of foreign matter. For this reason, there is a problem that must be solved for general use. That is, in applications that dislike dirt on the surface of the glass substrate and appearance foreign matter, that is, imaging-related applications, etc., it is required to suppress film peeling based on a glass substrate cleaning process or the like by a general-purpose method.

  With respect to such a point, it is possible to obtain excellent film peeling resistance by forming a silicon oxide film as the adhesion strengthening layer 3 on the glass substrate 2 with a physical film thickness greater than or equal to a predetermined thickness. Become. This is clear from the test results of the present inventors, but the theoretical consideration is not necessarily sufficient. However, from various test results, it is considered that film peeling of the adhesion strengthening layer 3 and thus the optical multilayer film 4 is suppressed based on the following actions.

  The greatest feature of the glass member 1 with an optical multilayer film of this embodiment is that the silicon oxide film which is the adhesion strengthening layer 3 has a thickness greater than or equal to a predetermined thickness. In general, a compressive stress is generated in a dense film formed by sputtering. The thicker the film is formed on the glass substrate, the more the compressive stress is integrated. Therefore, it is considered that the technique of simply increasing the film thickness is likely to promote film peeling. In addition, it is almost meaningless from the viewpoint of optical design to form a film having a refractive index close to 50 nm or more on a glass substrate. That is, it is considered that a completely different mechanism from the conventional concept contributes to the improvement of the film peeling resistance. Considering this mechanism, the following three points can be cited as interesting phenomena among the test results conducted by the present inventors.

(1) When the adhesion strengthening layer is extremely thick (50 nm or more, further 100 nm or more, or even 200 nm or more), film peeling resistance is improved. This is a film thickness of several times to ten times, considering that the film thickness of a general optical film is several nm to 30 nm per layer.
(2) A case where an optical multilayer film having a thickness of 5 μm is formed after forming the adhesive strength-enhancing layer with a thickness of 200 nm, and an optical multilayer film having a thickness of 5 μm after the adhesive strength-enhancing layer is formed with a thickness of 10 nm. Compared to the case of manufacturing, the former has a smaller amount of warpage of the glass substrate.
(3) In the steps from the formation of the adhesion enhancing layer to the formation of the optical multilayer film, the initial substrate temperature is set to 80 ° C. or higher compared to the case where the initial substrate temperature is less than 80 ° C. When film formation is performed (deposition temperature change is small), the effect of improving film peeling resistance is limited.

  From these test results, the suppression mechanism such as film peeling based on the adhesion strengthening layer 3 having a compressive stress and a film thickness of 50 nm or more is considered as follows. When film peeling occurs between the substrate and the film (in fact, this was almost the case in our tests), at least stress concentration that promotes film peeling exists in the vicinity of the interface between the substrate and the film. This is considered to occupy a large part of the cause of film peeling. For this reason, the stress concentration may be shifted from the substrate-film interface. It is very important to consider the vicinity of this interface when considering the occurrence of the fragile layer on the glass substrate surface and the film peeling caused by the above-described weakness. Further, since a compressive stress is generated in a dense film formed by sputtering film formation or the like, it is important to reduce the compressive stress.

Therefore, in the case where the adhesion strengthening layer 3 is formed near normal temperature from the above three phenomena and the optical multilayer film 4 is formed from this state as the film forming temperature rises, as schematically shown in FIG. It is considered to show behavior. The thermal expansion coefficient α of the silicon oxide film formed by sputtering is about 5.5 × 10 ⁻⁷ / ° C. When the thermal expansion coefficient of the glass substrate 2 to be used is larger than that of the silicon oxide film, as shown in FIG. The glass substrate 2 expands more greatly with respect to the adhesion strengthening layer 3 as shown in FIG. 4 (b) due to the temperature rise accompanying the progress (the substrate temperature rises), and the tensile stress effect due to the so-called thermal stress is the adhesion force. It begins to occur in the reinforcing layer 3.

  Since the deposition temperature further increases as the lamination of the optical multilayer film 4 proceeds, the lamination of the optical multilayer film 4 gradually proceeds at a high temperature as shown in FIG. The internal stress of the dense optical multilayer film 4 formed by the sputtering method is a compressive stress, and no thermal stress is generated at the time of film formation. Begins to occur. As the film forming temperature rises, the influence of tensile stress increases as the substrate is closer.

  When the thus formed glass member 1 with an optical multilayer film is taken out from the chamber of the sputtering apparatus and returned to room temperature, the adhesion strengthening layer 3 is formed near room temperature as shown in FIG. Therefore, only the internal stress (compressive stress) of the adhesion strengthening layer 3 acts during this period. On the other hand, in the film portion formed in a high temperature state (the second half portion of the optical multilayer film 4), thermal stress in the compression direction is generated due to the difference in the thermal expansion coefficient between the substrate and the film.

  The degree of thermal stress in the compression direction becomes smaller because the film forming temperature is lower as the film is closer to the substrate. Further, it can be considered that the tensile stress effect generated during the film formation remains due to the holding effect by the dense film farther from the substrate. In this way, the thicker the adhesion-strengthening layer 3 and the larger the thermal expansion coefficient of the glass substrate 2 (the larger the difference in thermal expansion from the adhesion-strengthening layer 3), the more the thermal stress tension. The stress effect is increased.

  Although the tensile stress effect generated in the vicinity of the substrate based on the thermal stress at the time of film formation is not so large as to offset the compressive stress (internal stress) of the optical multilayer film 4 and the adhesion strengthening layer 3, the adhesion strengthening layer 3 It works to reduce the inherent compressive stress. Such a compressive stress reduction effect remains even when the temperature returns to room temperature, and even if the stress of the adhesion-strengthening layer 3 remains as a compressive stress as a whole, the degree can be reduced. Therefore, the compressive stress concentration in the vicinity of the substrate-film interface is relaxed, and the stress concentration point is shifted to the inside of the adhesion strengthening layer 3. By these, it becomes possible to suppress film peeling from the interface between the glass substrate 2 and the adhesion reinforcing layer 3.

  In FIG. 4, the glass substrate 2 and the like are expressed flat, but in reality, a convex shape is formed according to the direction and magnitude of the stress. In FIG. 4A, a convex shape is formed due to the compressive stress of the adhesion reinforcing layer 3. In FIG. 4B, the degree of the convex shape is alleviated as a whole due to the expansion of the glass substrate 2 due to the temperature rise. In FIG. 4C, although the compressive stress of the optical multilayer film 4 acts, since the glass substrate 2 also expands, the degree of the convex shape as a whole slightly increases. In FIG. 4D, since the compressive stress due to thermal stress acts due to the shrinkage of the glass substrate 2, the convex shape increases as a whole, but the degree of the convex shape decreases as the film thickness of the adhesion strengthening layer 3 increases. .

  Thus, the physical film thickness of the adhesion strengthening layer 3 is an important factor for suppressing film peeling. That is, when the thickness of the adhesion strengthening layer 3 is increased to 50 nm or more, the tensile stress effect generated in the vicinity of the glass substrate 2 is increased, so that the compressive stress in the vicinity of the interface between the glass substrate 2 and the adhesion enhancing layer 3 is increased. It is possible to obtain a concentration relaxation effect and a stress concentration point movement effect. Therefore, it is possible to suppress film peeling from the interface between the glass substrate 2 and the adhesion enhancing layer 3 by applying the thick adhesion enhancing layer 3 having a thickness of 50 nm or more.

  In order to more effectively obtain the above-described compressive stress relaxation effect and stress concentration point moving effect, the thickness of the adhesion strengthening layer 3 is preferably 100 nm or more, and more preferably 200 nm or more. However, if the film thickness of the adhesion strengthening layer 3 becomes too thick, the film forming temperature increases greatly, so that the above-described effect becomes insufficient. For this reason, it is preferable that the film thickness of the adhesion strengthening layer 3 be 1 μm or less. Further, by applying the adhesion strengthening layer 3 and the optical multilayer film 4 having essentially compressive stress, it is possible to obtain the effect of suppressing the film peeling based on the relaxation of the compressive stress and the movement of the stress concentration point described above. It becomes.

The reason why the silicon oxide film is used as the adhesion-strengthening layer 3 is that the thermal expansion coefficient is 5.5 × 10 ⁻⁷ in addition to the adhesion and adhesion due to affinity with the glass substrate 2 as described above. Due to the low value of around / ° C. Actually, when the adhesion strengthening layer 3 is composed of a niobium oxide film having a thermal expansion coefficient of about 58 × 10 ⁻⁷ / ° C., a titanium oxide film having a thermal expansion coefficient of about 75 × 10 ⁻⁷ / ° C., or the like. The effect of suppressing the film peeling due to the relaxation of the compressive stress based on the difference in thermal expansion from the glass substrate 2 and the movement of the stress concentration point is not recognized.

Furthermore, it is preferable that the glass substrate 2 has a thermal expansion coefficient larger than that of the adhesion strengthening layer 3 in order to obtain an effect based on a difference in thermal expansion with the adhesion strengthening layer 3. However, when the thermal expansion coefficient of the glass substrate 2 is extremely large, the tensile stress effect due to the thermal stress generated in the vicinity of the glass substrate 2 becomes too large. On the contrary, when the tensile stress due to the thermal stress is remarkably increased, the film breaks easily. Therefore, the thermal expansion coefficient of the glass substrate 2 is preferably larger than that of the adhesion strengthening layer 3 and not more than 100 × 10 ⁻⁷ / ° C.

In the glass substrate 2 having a thermal expansion coefficient of less than 5.5 × 10 ⁻⁷ / ° C., the above-described relaxation effect of compressive stress due to thermal stress cannot be expected, but the thermal expansion coefficients of the glass substrate 2 and the adhesion strengthening layer 3 are close. Therefore, by increasing the thickness of such an adhesion strengthening layer 3, a high refractive index film such as a niobium oxide film or a titanium oxide film having a large thermal expansion coefficient can be separated from the interface with the glass substrate 2. . However, since such an effect becomes insufficient if the thermal expansion coefficient of the glass substrate 2 is too small, the thermal expansion coefficient of the glass substrate 2 is preferably 5 × 10 ⁻⁷ / ° C. or more. Furthermore, since the glass substrate 2 having a low thermal expansion coefficient is less likely to be weakened by cleaning, that is, has high weather resistance, the film peeling resistance is improved only by the effect of improving the adhesive strength of the adhesive strength reinforcing layer 3.

  The formation of the adhesion enhancing layer 3 and the optical multilayer film 4 is preferably carried out continuously. When forming the adhesion strengthening layer 3 using the transition state in reactive sputtering, it is preferable to form the optical multilayer film 4 by applying the same reactive sputtering in consideration of the continuity of the film formation. . Regarding the conditions at the time of film formation at that time, it is preferable that the temperature of the glass substrate 2 at the start of film formation is less than 80 ° C. as described above. When the film formation start temperature exceeds 80 ° C., it is not possible to sufficiently obtain the effect due to the film formation temperature increasing as the film formation proceeds. The film formation start temperature of the adhesion enhancing layer 3 is more preferably 40 ° C. or lower. It should be noted that the formation of the adhesion-strengthening layer 3 and the optical multilayer film 4 exhibits the same effect even when carried out in separate steps.

  In addition, if the film formation in the reactive state in the reactive sputtering is frequently used in the vicinity of the glass substrate 2 in the film formation of the optical multilayer film 4, the above-described effect is limited or disappears. Regarding this phenomenon, the glass substrate 2 has an extremely large coefficient of thermal expansion because the film formation rate is probably low and the amount of oxygen plasma generated as a heat source is large, so that the temperature rise during film formation becomes significant near the substrate. It is thought that it becomes the same using. That is, it is considered that this is an example of a significant deviation from the action of avoiding the concentration of stress concentration points in the vicinity of the substrate-film interface.

  The effect of reducing the compressive stress and the effect of separating the stress concentration point from the substrate interface in the process of forming the adhesion strengthening layer 3 and the optical multilayer film 4 described above are limited to the film formation using the transition state in reactive sputtering. Instead, it can also be obtained by a normal reactive sputtering method or the like. Furthermore, considering that the above-mentioned effect can be obtained when both the adhesion strengthening layer 3 and the optical multilayer film 4 have compressive stress, a film forming method that can obtain a film having compressive stress other than sputtering is applied. Is also possible. For example, the present invention can also be applied to vapor deposition film formation using ion assist that can form a dense film similar to sputtering film formation.

  In addition, although the suppression mechanism of the film peeling based on the adhesion strengthening layer 3 is not necessarily fully elucidated, a silicon oxide film having a compressive stress and a film thickness of 50 nm or more is used for the adhesion enhancing layer 3. When the case is compared with the case where a silicon oxide film having a film thickness of less than 50 nm is used for the adhesion strengthening layer 3, the former is less effective in suppressing film peeling than the latter from the evaluation result of film peeling of the optical multilayer film 4. These are clearly phenomenologically confirmed. Therefore, the configuration of the glass member 1 with an optical multilayer film of this embodiment is still effective.

  Next, specific examples of the present invention and evaluation results thereof will be described. In addition, the following description does not limit this invention, The modification | change in the form along the meaning of this invention is possible.

  In the following examples, a batch type carousel type reactive sputtering apparatus was used. The sputtering apparatus has a function for maintaining a transition state in reactive sputtering. In addition, unless otherwise specified, the cleaning process including alkali cleaning applies a cleaning process using an alkaline cleaner containing a surfactant and an aqueous sodium hydroxide solution, and also includes a water cleaning process and a cleaning process using isopropyl alcohol, etc. Is used in combination. When stronger substrate cleaning is required, immersion cleaning with a strong alkali cleaner CS-718 (containing 30% by mass of KOH) manufactured by Nippon Surface Science Co., Ltd. was performed immediately before the normal alkali cleaning step described above. . For strong alkaline cleaning, it will be described each time.

  Moreover, the evaluation of the film peeling resistance of the optical multilayer film formed on the glass substrate was carried out as follows. First, using a general glass cutting or the like on the surface of the optical multilayer film formed on the glass substrate, several scratches reaching the glass substrate with a distance of about 2 mm and a length of about 10 mm are linearly formed. Are formed in a lattice shape. Further, an adhesive tape (width: 12 to 19 mm) defined in JIS Z1522 is attached onto a lattice-shaped scratch, and this adhesive tape is quickly pulled in a direction perpendicular to the film surface of the optical multilayer film to form a film of the optical multilayer film. The state of occurrence of peeling was confirmed.

  Evaluation criteria are as follows: ◎ when there is no film peeling, ◯ when there is a slight occurrence of linear peeling starting from part of the lattice-like scratch, and surface starting from part of the lattice-like scratch △ indicates that the film-like film peeling has occurred partially, x indicates that the film-like film peeling has occurred on the majority of the tape surface, and surface film peeling occurs on most of the tape surface. A portion where the film is not peeled off remains, and a portion that can be judged as an intermediate state between Δ and × is indicated as Δ ×.

Example 1
First, borosilicate glass D263T (thermal expansion coefficient: 72 × 10 ⁻⁷ / ° C.) manufactured by Shot Corp. was prepared as a glass substrate, and this was cut into a shape of 95 × 95 × 0.3 mm. After such a glass substrate was immersed and washed in the above-described strong alkali cleaning agent for 30 minutes, a cleaning process including the above-described normal alkali cleaning was performed. Next, an adhesion strengthening layer made of a silicon oxide film having a thickness of 200 nm is formed on the glass substrate after the alkali cleaning by utilizing a transition state in reactive sputtering, and a niobium oxide / silicon oxide alternately laminated film is formed thereon. An IR cut film consisting of The film thickness of the IR cut film was about 5 μm.

  The substrate temperature at the start of film formation was about the same as room temperature (25 to 30 ° C.). As a result of the actual measurement of the film formation temperature, the substrate temperature at the end of film formation was about 160 ° C. It was confirmed that both the adhesion strengthening layer made of the silicon oxide film and the IR cut film made of the alternately laminated film of niobium oxide / silicon oxide had compressive stress. The glass member with an optical multilayer film produced in this way was allowed to stand on a flat measurement table with the film surface facing up, and the amount of warpage (having a convex shape) at the center was measured using a factory microscope. As a result, the amount of warpage was 1.042 mm. Furthermore, when the film peeling resistance of the glass member with an optical multilayer film was evaluated according to the method described above, the evaluation result of the film peeling resistance was ◎.

(Example 2)
A glass substrate in which borosilicate glass FP-1 (thermal expansion coefficient: 52 × 10 ⁻⁷ / ° C.) manufactured by AGC Techno Glass Co., Ltd. was molded into a shape of 95 × 95 × 0.3 mm and the surface was polished was described above. After immersing and washing in a strong alkaline detergent for 30 minutes, a washing process including the above-described ordinary alkali washing was performed. On such a glass substrate, an adhesion enhancing layer composed of a silicon oxide film having a thickness of 200 nm and an IR cut film having a thickness of about 5 μm were formed in the same manner as in Example 1. When the film peeling resistance of the glass member with an optical multilayer film thus obtained was evaluated according to the method described above, the evaluation result of the film peeling resistance was ◎.

(Example 3)
A glass glass C-52B (coefficient of thermal expansion: 81 × 10 ⁻⁷ / ° C.) manufactured by AGC Techno Glass Co., Ltd. was molded into a shape of 50 × 50 × 0.5 mm and the surface was polished as described above. A cleaning process including normal alkali cleaning was performed. On such a glass substrate, an adhesion enhancing layer composed of a silicon oxide film having a thickness of 200 nm and an IR cut film having a thickness of about 5 μm were formed in the same manner as in Example 1. When the film peeling resistance of the glass member with an optical multilayer film thus obtained was evaluated according to the method described above, the evaluation result of the film peeling resistance was ◎.

Example 4
As a glass substrate, borosilicate glass D263T (thermal expansion coefficient: 72 × 10 ⁻⁷ / ° C.) manufactured by Schott was prepared and cut into a shape of 95 × 95 × 0.3 mm. After such a glass substrate was immersed and washed in the above-described strong alkali cleaning agent for 30 minutes, a cleaning process including the above-described normal alkali cleaning was performed. By applying the same method as in Example 1 on this glass substrate, an adhesion enhancing layer made of a 50 nm thick silicon oxide film and an IR cut film having a thickness of about 5 μm were formed. When the film peeling resistance of the glass member with an optical multilayer film thus obtained was evaluated according to the above-described method, the evaluation result of the film peeling resistance was ◯.

(Example 5)
In Example 4 described above, a glass member with an optical multilayer film was produced in the same manner as in Example 4 except that the film thickness of the adhesion enhancing layer made of the silicon oxide film was set to 70 nm. When the film peeling resistance of the glass member with an optical multilayer film was evaluated according to the method described above, the evaluation result of the film peeling resistance was “good”.

(Examples 6 to 8)
Corning borosilicate glass Eagle 2000 (coefficient of thermal expansion: 32 × 10 ⁻⁷ / ° C.) as the glass substrate of Example 6, and Schott silicate glass B270 (thermal expansion coefficient) as the glass substrate of Example 7 : 94 × 10 ⁻⁷ / ° C.), quartz glass (thermal expansion coefficient: 5 × 10 ⁻⁷ / ° C.) manufactured by Murakami Kaimeidou Co., Ltd. was prepared as the glass substrate of Example 8. After these glass substrates were cut into a shape of 95 × 95 × 0.3 mm, a cleaning process including the above-described normal alkali cleaning was performed. In addition, the glass substrate of Example 6 was immersed and washed in the above-described strong alkaline detergent for 30 minutes, and then subjected to a washing step including the above-described ordinary alkali washing.

  By applying the same method as in Example 1 on these glass substrates, an adhesion strengthening layer made of a silicon oxide film having a thickness of 200 nm and an IR cut film having a thickness of about 5 μm were formed. When the film peeling resistance of the glass member with an optical multilayer film thus obtained was evaluated according to the method described above, the evaluation result of the film peeling resistance of Example 6 was ◎, and the film peeling resistance of Example 7 was The evaluation result was ◎, and the evaluation result of the film peeling resistance of Example 8 was ◎.

(Comparative Example 1)
In Example 1 mentioned above, the glass member with an optical multilayer film was produced like Example 1 except the film thickness of the adhesion strengthening layer which consists of a silicon oxide film having been 20 nm. The amount of warpage of the central portion of the glass member with an optical multilayer film was measured in the same manner as in Example 1. As a result, the amount of warpage was 1.161 mm. Furthermore, when the film peeling resistance of the glass member with an optical multilayer film was evaluated according to the method described above, the evaluation result of the film peeling resistance was Δ.

(Comparative Example 2)
In Example 2 described above, a glass member with an optical multilayer film was produced in the same manner as Example 2 except that the film thickness of the adhesion enhancing layer made of the silicon oxide film was 20 nm. When the film peeling resistance of the glass member with an optical multilayer film was evaluated according to the method described above, the evaluation result of the film peeling resistance was x.

(Comparative Examples 3-5)
Using the same glass substrate (Comparative Examples 3 to 5) as in Examples 6 to 8 described above, an adhesion strengthening layer made of a silicon oxide film having a thickness of 20 nm and an IR cut film having a thickness of about 5 μm were respectively formed. Formed. When the film peeling resistance of the glass member with an optical multilayer film thus obtained was evaluated according to the method described above, the evaluation result of the film peeling resistance of Comparative Example 3 was x, and the film peeling resistance of Comparative Example 4 was The evaluation result was Δ, and the evaluation result of the film peeling resistance of Comparative Example 5 was x.

(Comparative Example 6)
A cleaning step including the above-described normal alkali cleaning was performed on a glass substrate made of AGC Techno Glass Co., Ltd. made of fluorophosphate glass / NF-50 (thermal expansion coefficient: 129 × 10 ⁻⁷ / ° C.). By applying the same method as in Example 1 on such a glass substrate, an adhesion strengthening layer made of a silicon oxide film having a thickness of 200 nm and an IR cut film having a thickness of about 5 μm were formed. When the film peeling resistance of the glass member with an optical multilayer film thus obtained was evaluated according to the method described above, the evaluation result of the film peeling resistance was x.

(Reference Example 1)
As a glass substrate, borosilicate glass D263T (thermal expansion coefficient: 72 × 10 ⁻⁷ / ° C.) manufactured by Schott was prepared and cut into a shape of 95 × 95 × 0.3 mm. After such a glass substrate was immersed and washed in the above-described strong alkali cleaning agent for 30 minutes, a cleaning process including the above-described normal alkali cleaning was performed. Next, an adhesion strengthening layer made of a silicon oxide film having a thickness of 200 nm and an IR cut film having a thickness of about 5 μm were formed on the glass substrate by reactive sputtering similar to Example 1. However, here, the substrate was heated to form an adhesion strengthening layer and an IR cut film. The substrate temperature was such that the substrate temperature at the start of film formation was 160 ° C. When the film peeling resistance of the glass member with an optical multilayer film thus obtained was evaluated according to the method described above, the evaluation result of the film peeling resistance was Δ.

(Reference Example 2)
A glass member with an optical multilayer film was produced in the same manner as in Reference Example 1 except that in Example 1 described above, the substrate was heated so that the substrate temperature at the start of deposition of the adhesion-strengthening layer was 80 ° C. When the film peeling resistance of the glass member with an optical multilayer film was evaluated according to the method described above, the evaluation result of the film peeling resistance was Δ.

  Tables 1 and 2 collectively show the configurations and evaluation results of the glass members with optical multilayer films according to the above-described examples, comparative examples, and reference examples. As is apparent from Tables 1 and 2, by applying a silicon oxide film having a film thickness of 50 nm or more as the adhesion-strengthening layer, it is possible to increase the film resistance of the optical multilayer film. In addition, the substrate temperature at the start of film formation of the adhesion-enhancing layer is less than 80 ° C. (more preferably 40 ° C. or less) so that the temperature change due to the film formation process can be sufficiently obtained. It can be seen that the film peeling property is improved.

It is a schematic diagram which shows the structure of the glass member with an optical multilayer film of this invention. It is a schematic diagram for demonstrating the three states and hysteresis in reactive sputtering. It is a schematic diagram which shows the structure of the plasma emission monitoring system in a reactive sputtering apparatus. It is a figure which shows typically the behavior of each component at the time of film-forming of an adhesive force reinforcement layer and an optical multilayer film.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Glass member with an optical multilayer film, 2 ... Glass substrate, 3 ... Adhesion-strengthening layer, 4 ... Optical multilayer film, 10 ... Reactive sputtering apparatus.

Claims (13)

A glass member with an optical multilayer film comprising a glass substrate and an optical multilayer film formed on the main surface of the glass substrate via an adhesion strengthening layer and having a compressive stress,
The adhesion enhancing layer is a sputtered film formed in a transition state in reactive sputtering , and has a film thickness of 50 nm or more, a compressive stress, and a stoichiometrically biased silicon oxide film A glass member with an optical multilayer film, comprising: The glass member with an optical multilayer film according to claim 1, wherein the optical multilayer film is a sputtered film. The glass substrate according to claim 1 or claim 2 the optical multilayer film-coated glass member according characterized by having a thermal expansion coefficient in the range of 5~100 × 10 ^-7 / ℃. 4. The glass member with an optical multilayer film according to claim 3, wherein the glass substrate has a thermal expansion coefficient larger than that of the adhesion-strengthening layer. The glass member with an optical multilayer film according to any one of claims 1 to 4 , wherein the glass substrate is made of silicate glass or phosphate glass. The glass member with an optical multilayer film according to any one of claims 1 to 5 , wherein the adhesion enhancing layer is formed on a surface of the glass substrate that has been cleaned with an alkaline cleaner. . The optical multilayer film includes a laminated film in which a low refractive index film made of silicon oxide and a high refractive index film made of at least one selected from niobium oxide, titanium oxide, and tantalum oxide are alternately arranged. The glass member with an optical multilayer film according to any one of claims 1 to 6 . The main surface of the glass substrate with the substrate temperature at the start of film formation being less than 80 ° C. is utilized with the transition state in reactive sputtering, has a film thickness of 50 nm or more, has compressive stress , and is stoichiometric. A step of sputter-depositing an adhesion enhancing layer made of a biased silicon oxide film;
Forming an optical multilayer film having a compressive stress on the adhesion strengthening layer. A method for producing a glass member with an optical multilayer film. The method for producing a glass member with an optical multilayer film according to claim 8, wherein the optical multilayer film is formed by a sputtering method. Further, the surface of the glass substrate comprises a step of washing with an alkaline cleaner, claim 8 or claim 9 wherein the adhesion reinforcing layer and forming on the cleaned surface of the glass substrate The manufacturing method of the glass member with an optical multilayer film of this. Process for producing an optical multilayer film glass member of any one of claims 8 through claim 10, wherein the glass substrate having a thermal expansion coefficient in the range of 5~100 × 10 ^-7 / ℃. The method for producing a glass member with an optical multilayer film according to any one of claims 8 to 11 , wherein the step of forming the adhesion reinforcing layer and the process of forming the optical multilayer film are continuously performed. Method. The step of forming the optical multilayer film includes a step of alternately forming a low refractive index film made of silicon oxide and a high refractive index film made of at least one selected from niobium oxide, titanium oxide, and tantalum oxide. The method for producing a glass member with an optical multilayer film according to any one of claims 8 to 12 .

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