Film Thickness Measurement Device

Abstract

To measure with good accuracy the composition and film thickness of an oxide thin film, etc. that has occurred to solder and electrode surfaces.SOLUTION: A counter electrode 112 and a reference electrode 111 are formed in a solid electrolyte 171. An adhesion part is disposed around the solid electrolyte 171 and the thin film 123 to be measured, with the inside of the adhesion part filled with an electrically charged liquid 124. The electrically charged liquid 124 is spread to the tip of the solid electrolyte 171. A voltage is applied to the electrode 110, the reference electrode 111 and the counter electrode 112 by a potentiostat 119, and the thin film 123 is electrochemically reduced. The thin film 123 is irradiated with incident light 114a2 coming from a light generator 108, and reflected light 114b is received by a light receiver 117 so as to measure spectral reflectance. The composition and film thickness of the thin film 123 are determined from a plateau potential due to electrochemical reduction and the result of film thickness simulation by spectral reflectance.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a film thickness measuring device and method for quantitatively analyzing surface oxide films formed on the surface of silicon wafers, organic thin films on the copper foil surface of printed circuit boards, surface oxide films, and surface oxide films formed by soldering. It also relates to a film removal device and film removal method for easily removing surface organic thin films and surface oxide films. It also relates to a head for electrodes, etc., used in electrochemical reduction. [Background technology]

[0002] During the IC manufacturing process, semiconductor wafers are manufactured using special heat treatments tailored to the purpose. Oxygen in the atmosphere forms a surface oxide film on the copper foil of printed circuit boards, and inorganic and organic films adhere to the copper foil surface due to oxidation and contamination. Surface oxide films form on the copper foil surface during soldering. Surface oxide films affect corrosion resistance, solder adhesion, and device reliability, and are therefore an issue, so evaluating their composition and film thickness is important in manufacturing.

[0003] To prevent defects such as non-fusion during board mounting or flip-chip connection of BGA packages, it is necessary to quantitatively measure the oxide film on the bump surface during reflow and take appropriate measures. Therefore, it is important to analyze the state of the oxide film on the solder bump surface and evaluate its thickness and material composition.

[0004] The composition of surface oxide films is complex because it is affected by the heat treatment temperature, atmosphere, and chemical components of the metal material. The thickness of surface oxide films ranges from a few nanometers at very thin locations to several tens of micrometers at thick locations.

[0005] Patent Document 1 describes a method for quantitatively analyzing oxide films on metal surfaces, in which a glow discharge is performed to measure the emission intensity ratio between a target element and a matrix element, and the concentration of the target element is determined using a calibration curve.

[0006] The thickness of thin films has been evaluated using so-called surface analysis methods such as secondary ion mass spectrometry (SIMS), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS) to evaluate the composition of oxide films along with the compositional changes in the depth direction from the surface. However, these methods have been rarely used because they are not fast enough and lack the wide analytical range required to obtain average information on the metal surface. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 9-273992 Summary of the Invention [Problem to be solved by the invention]

[0008] Secondary ion mass spectrometry (SIMS), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS) have been rarely used because they lack the required analytical range.

[0009] Glow discharge optical emission spectroscopy (hereinafter referred to as GDS) has the problem that fluctuations in the spectrometer system and vacuum pumping system can cause the emission intensity to become unstable, resulting in a decrease in quantitative accuracy. [Means for solving the problem]

[0010] In the film thickness measurement device of the present invention, a counter electrode 112 and a reference electrode 111 are formed on a solid electrolyte 171. A contact area is arranged around the solid electrolyte 171 and the thin film 123 to be measured. The inside of the contact area is filled with a charged liquid 124. The tip of the solid electrolyte 171 is permeated with or filled with the charged liquid 124.

[0011] A voltage is applied to the electrode 110, the reference electrode 111, and the counter electrode 112 by the potentiostat 119, causing electrochemical reduction of the thin film 123. Incident light 114a2 from the light generator 108 is irradiated onto the thin film 123, and reflected light 114b is received by the light receiver 117 to measure the spectral reflectance. The composition and film thickness of the thin film 123 are determined from the plateau potential due to electrochemical reduction, the time over which the plateau potential changes, and the film thickness simulation results based on the spectral reflectance. [Effects of the Invention]

[0012] By performing spectroscopic film thickness measurement and electrochemical reduction, the composition, structure, and film thickness of the thin film material to be measured can be measured with high accuracy.

[0013] The cleaning solution can easily remove protective films and the like on the thin film, thereby exposing the thin film to be measured, and the film thickness of the oxide thin film material to be measured can be easily measured.

[0014] The head portion that performs electrochemical reduction is made of solid electrolyte 171. This allows the head portion to be small and space-saving. In addition, the electrolyte 124 is permeated into a sponge-like material at the tip of the head. This prevents the electrolyte 124 from leaking out, and allows the electrolyte 124 and thin film 123 to be tightly attached to each other. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram and an explanatory diagram of a film thickness measuring device according to the present invention; [Figure 2] 1A and 1B are diagrams illustrating a configuration of a film thickness measurement device and a film thickness measurement method according to the present invention. [Figure 3] 1A and 1B are diagrams illustrating a configuration of a film thickness measurement device and a film thickness measurement method according to the present invention. [Figure 4] 1A and 1B are diagrams illustrating a configuration of a film thickness measurement device and a film thickness measurement method according to the present invention. [Figure 5] 1A and 1B are diagrams illustrating a configuration of a film thickness measurement device and a film thickness measurement method according to the present invention. [Figure 6]1A and 1B are diagrams illustrating a configuration of a film thickness measurement device and a film thickness measurement method according to the present invention. [Figure 7] 1A and 1B are diagrams illustrating a configuration of a film thickness measurement device and a film thickness measurement method according to the present invention. [Figure 8] 1A and 1B are diagrams illustrating a configuration of a film thickness measurement device and a film thickness measurement method according to the present invention. [Figure 9] FIG. 2 is an explanatory diagram of a film thickness measurement method according to the present invention. [Figure 10] FIG. 2 is an explanatory diagram of a film thickness measurement method according to the present invention. [Figure 11] FIG. 2 is an explanatory diagram of a film thickness measurement method according to the present invention. [Figure 12] FIG. 2 is an explanatory diagram of a film thickness measurement method according to the present invention. [Figure 13] 1 is an explanatory diagram of a film thickness measurement device and a film thickness measurement method according to the present invention. [Figure 14] FIG. 1 is a flowchart of a film thickness measurement method according to the present invention. [Figure 15] 1A and 1B are diagrams illustrating a configuration of a film thickness measurement device and a film thickness measurement method according to the present invention. [Figure 16] 1A and 1B are a configuration diagram and an explanatory diagram of a head portion of a film thickness measuring device according to the present invention; [Figure 17] 1A and 1B are a configuration diagram and an explanatory diagram of a head portion of a film thickness measuring device according to the present invention; [Figure 18] 1A and 1B are a configuration diagram and an explanatory diagram of a head portion of a film thickness measuring device according to the present invention; [Figure 19] 1A and 1B are a configuration diagram and an explanatory diagram of a head portion of a film thickness measuring device according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0016] The following describes a configuration diagram of a film thickness measurement device and a film thickness measurement method according to an embodiment of the present invention with reference to the accompanying drawings. The present invention is not limited to a film thickness measurement device and a film thickness measurement method, but also relates to a surface processing or treatment method for steel materials, solder, plated sheets, bumps such as ICs, copper foil, printed circuit boards, semiconductor-related products such as silicon wafers, steel materials, electronic devices, electrical devices, mechanical devices, precision devices, structures, coating materials, etc.

[0017] In the drawings for explaining the embodiments of the invention, elements having the same function or similarity are given the same reference numerals, and matters not necessary for the explanation are omitted from the drawings. For ease of explanation, drawings may be simplified or schematic. Explanations may also be omitted in the specification.

[0018] The embodiments of the present invention can be combined in part or in whole with the embodiments described in this specification and drawings, and can also be combined or implemented with partial changes or modifications.

[0019] 1 is a block diagram of a film thickness measurement device and an explanatory diagram of a film thickness measurement method according to the present invention. The film thickness measurement device according to the present invention not only measures the film thickness of a target film, but also has the function of removing oxide films, organic films, organic solderability preservatives (OSPs), and the like from the surface.

[0020] The cleaning liquid LA for removing the organic film and the organic protective film (OSP) is filled in the liquid tank 104a. The amount of the cleaning liquid LA filled in the liquid tank 104a is constantly measured or monitored, and a constant amount is filled or allowed to penetrate. The cleaning liquid LA is, for example, a solvent. The cleaning liquid LA is also replaced with a rinse liquid as appropriate.

[0021] If the OSP is water-soluble, the cleaning solution (LA, etc.) should be based on the same water-soluble solvent. For example, HO-(CH2)2-OH (ethylene glycol) is freely miscible with water. HO-(CH2)2-O(CH2)3CH3 (ethylene glycol, monobutyl ether) is soluble in water. HO-(CH2)2-O(CH2)5CH3 (ethylene glycol, monohexyl ether) is slightly soluble in water.

[0022] Regarding the relationship between the cleaning liquid LA and the rinse liquid, when the cleaning liquid LA is methyl alcohol, examples of the rinse liquid include acetone, ethanol base, and isopropyl alcohol (IPA). When the cleaning liquid LA is ethanol, examples of the rinse liquid include acetone, ethanol base, and isopropyl alcohol (IPA). When the cleaning liquid LA is propylene alcohol, examples of the rinse liquid include acetone.

[0023] When the cleaning liquid LA is 1-butanol, examples of the rinse liquid include acetone, an ethanol base, and isopropyl alcohol (IPA).When the cleaning liquid LA is ethylene glycol, examples of the rinse liquid include isopropyl alcohol (IPA). The liquid tank 104b is filled with the electrolyte LB124. The amount of the electrolyte LB124 filled in the liquid tank 104b is constantly measured or grasped, and a constant amount is filled.

[0024] Examples of the electrolyte 124 include potassium chloride (KCl), sodium chloride (NaCl), an aqueous hydrochloric acid solution, sodium hydroxide, a boric acid solution, and a sodium tetraborate solution.

[0025] The electrolytic solution 124 may be a solid electrolyte material or a gel electrolytic solution. The electrolytic solution 124 may be impregnated into a sponge or the like and used. The electrolytic solution 124 may be filled between the container 105 and the permeable membrane 172. When the electrolyte material is a solid electrolyte material or a gel electrolyte solution, the defoamer 103b and the solution reservoir 162b are not necessary, and there is no need to circulate the liquid inside the container 105.

[0026] An example of a solid electrolyte is stabilized zirconia. Stabilized zirconia is zirconia (zirconium dioxide ZrO2) to which a few percent of magnesium oxide MgO, calcium oxide CaO, or rare earth oxide is added. Another example is yttria-stabilized zirconium (ZrO2-Y2O3). The solid electrolyte material will be described as solid electrolyte 171 or solid electrolyte 171 part.

[0027] When oxides such as yttrium oxide (YO), calcium oxide (CaO), cerium oxide (CeO), and magnesium oxide (MgO) are added to zirconia, the cubic crystals can be stable even at room temperature. Zirconia in which the cubic crystals are stable at room temperature is called stabilized zirconia or partially stabilized zirconia, and is used as the solid electrolyte 171 in the present invention.

[0028] There are two main methods for producing the zirconia used in the head of this invention: wet refining and dry refining. Both methods use zirconium ores such as zircon and hadelite as raw materials. In the wet refining method, selected ores are melted with caustic soda, then decomposed and concentrated with hydrochloric acid. After further processes such as washing and filtration, the resulting zirconium hydroxide is fired and pulverized to produce zirconia powder.

[0029] In the dry refining method, pure zirconia is produced by crushing ore to remove impurities and then repeatedly filtering the ore. In the present invention, the counter electrode 112 and reference electrode 110 are formed on zirconia produced by the wet refining method or the dry refining method using plating technology. Alternatively, the counter electrode 112 and reference electrode 110 are formed by sintering.

[0030] In this specification, drawings, etc., it is described that the electrochemical reduction reaction is carried out by filling the container 105 with the electrolyte solution 124, but the electrolyte solution 124 may be a solid electrolyte material or a gel electrolyte solution. The electrolyte solution 124 or the electrolytic material 124 is not limited to liquids. It also includes solid electrolyte materials and gel electrolyte materials.

[0031] In the present invention, the container 105 has the substrate 109 or the like as a lid or the like, and the space between the lid (printed circuit board or the like) and the container 105 is filled with the electrolyte 124, but this is not limited to this. For example, the electrolyte 124 may be used in a state where it is permeated into or mixed with glass wool, fiber, organic matter such as agar, or the like.

[0032] A material containing or permeating the electrolyte 124, such as agar, or a permeable structure (permeable membrane 172) may be disposed or installed at a portion where the electrolyte 124 or the like comes into contact with or is in contact with the thin film 123 or the like. When the agar or other portion containing the electrolyte or the like comes into contact with or is in contact with the thin film 123 or the like, an electrochemical reduction action is realized.

[0033] To prevent leakage of the electrolyte 124, it is preferable to form or arrange a permeation membrane 172 as shown in Figures 2, 15, etc. Examples of the permeation membrane 172 include cellophane, a precipitated membrane of copper ferrocyanide, a collodion membrane, and a bladder membrane. Other examples include porous membranes of regenerated cellulose (cellophane), acetyl cellulose, polyacrylonitrile, Teflon (registered trademark), polyester polymer alloy, or polysulfone.

[0034] Polyacrylate may be contained in or mixed with the electrolyte 124. By impregnating glass wool, rayon, polyester, polypropylene, polyethylene, agar, or the like with the electrolyte 124, leakage or elution of the electrolyte 124 can be suppressed.

[0035] Due to the action of the permeable membrane 172, the electrolyte 124 does not leak out even when it comes into contact with the thin film 123. Furthermore, the electrolyte 124 can come into contact with, be immersed in, or be filled into the thin film 123, etc., via the permeable membrane 172, thereby allowing the thin film 123, etc., to be electrochemically reduced.

[0036] The defoamer 103 is a defoaming device that removes gas from the solution. Examples of defoamers include those that use vacuum (reduced pressure) or centrifugal force. Other defoaming devices that use ultrasonic waves or a gas-permeable membrane may also be used. By removing air bubbles from the liquid, the strength, properties, and surface characteristics of the product can be made uniform, improving yield and quality.

[0037] A vacuum degassing device uses a vacuum pump to reduce the pressure in the solution, causing bubbles contained in the liquid to expand. The expanded bubbles rise to the liquid surface due to buoyancy, and over time, the liquid film on the surface breaks down, causing the bubbles to be expelled into the decompressed air. A centrifugal degassing device uses the principle that liquid and gas, which have different densities, are separated by centrifugal force when a container containing a solution rotates and revolves around its axis.

[0038] The cleaning liquid (rinse liquid) LA defoamed by the defoamer 103a is held in the solution reservoir 162a. The liquid volume in the solution reservoir 162a is detected by a level detector 161a and controlled by a liquid volume control unit 120 so as not to exceed a predetermined liquid volume.

[0039] The electrolyte solution LB degassed by the degasser 103b is stored in the solution reservoir 162b. The liquid volume in the solution reservoir 162b is detected by a level detector 161b and controlled by a liquid volume control unit 120 so that the liquid volume does not exceed a predetermined liquid volume or does not fall below the predetermined liquid volume. The amounts of the cleaning liquid (rinse liquid) LA and the electrolyte LB poured into the liquid tanks are controlled by a liquid amount control unit 120 so that the liquid amounts do not exceed a certain value.

[0040] The solenoid valve 101a controls whether to supply or cut off the cleaning liquid (rinse liquid) LA to the pump 102a, and the solenoid valve 101b controls whether to supply or cut off the electrolyte LB to the pump 102a.

[0041] A flow meter (not shown) is attached to the pump 102. The pump 102a controls the amount of cleaning liquid (rinse liquid) LA or electrolyte LB injected into the container 105 by means of the torque and rotation speed.

[0042] The cleaning liquid (rinse liquid) LA or the electrolyte LB124 is injected into the container 105 through a liquid injection pipe 106 connected to the container 105. The cleaning liquid (rinse liquid) LA or the electrolyte LB124 is discharged from the container 105 through a liquid drain pipe 107.

[0043] A circulation fan 122 that agitates the poured cleaning liquid (rinse liquid) LA or electrolyte LB is disposed inside the container 105. The circulation fan 122 rotates as necessary to agitate or circulate the liquid inside the container 105. When discharging the solution, the fan rotates in a direction that sends the solution to the drain pipe 107.

[0044] The cleaning liquid LA or the electrolyte LB is injected through the liquid injection tube 106 into the area in contact with the thin film 123, etc. The cleaning liquid LA or the electrolyte LB is drained through the liquid drain tube 107 from the area in contact with the thin film 123, etc.

[0045] In the embodiments of the present invention, for ease of understanding or explanation, an electrode 110 is formed on a printed circuit board 109, and an oxide film 123, an organic film 126, etc. are formed on the electrode 110.

[0046] The film thickness measurement device of the present invention is configured so that a solution 124 is filled in a container 105 with a substrate 109 as a lid. The solution 124 is an electrolyte solution LB or a cleaning solution LA. The tip of the container 105 may be sealed with a material such as agar that is permeable to the electrolyte solution LB or the cleaning solution LA. Cleaning and electrochemical reduction are carried out by bringing the agar or the like or the permeable membrane 172 into contact with the thin film 123.

[0047] An electrode 110 is disposed inside the container 105. The electrode 110 is part of a wiring pattern formed on the substrate 109, and functions as a working electrode (WE) by applying a predetermined potential to the wiring pattern. In addition, a counter electrode (CE) and a reference electrode (RE) are disposed in the solid electrolyte 171.

[0048] It functions as a working electrode (WE). In addition, by applying a constant current between the counter electrode (CE) of the solid electrolyte 171 and the working electrode (WE) and controlling the potential with the reference electrode (RE), the forming materials of the thin film 123 of the working electrode (WE) are electrochemically reduced.

[0049] Electrodes are classified into polarizable electrodes and non-polarizable electrodes. A polarizable electrode is an electrode whose potential can be changed without passing a current. This electrode is used as the working electrode 110 or counter electrode 112. A non-polarizable electrode is an electrode 111 through which a current flows when an attempt is made to change the potential, and is usually used as the reference electrode (RE) 111. Examples of polarizable electrodes used as the counter electrode (CE) 112 include platinum, gold, carbon, and mercury. Platinum is preferred because of its high physical and chemical stability.

[0050] When using in aqueous systems, care must be taken because hydrogen molecules are generated in the reduction direction. In the oxidation region, the electrode surface oxidizes and a corresponding reduction current flows. Similar surface redox couples are found on most solid metal electrodes.

[0051] In systems containing high concentrations of chloride ions, increasing the oxidation potential may result in elution as chloroplatinate ions. Gold is often referred to as platinum. Because gold's overvoltage for the generation of hydrogen molecules is greater than that of platinum, the potential window in the reduction region is wide. A large amount of chloride ions is included, deepening the oxidation potential.

[0052] There are many types of carbon electrodes. The most commonly used is glassy carbon. Microscopically, it is graphite, but macroscopically, as the name suggests, it has an amorphous structure. Graphite is a layered structure of two-dimensional planes formed by the condensation of benzene rings. There is anisotropy due to the orientation of the planes (basal planes and edge planes).

[0053] The reference electrode (RE) 111 is non-polarizable. If an attempt is made to change the potential, a surface reaction occurs on the electrode itself, causing a sudden increase in current. It is preferable to use the reference electrode (RE) 111 without passing current in order to maintain a constant potential. The standard is a hydrogen electrode. When hydrogen molecules and hydrogen ions are in equilibrium at the standard state on the platinum surface, the potential shown by the platinum electrode is defined as zero.

[0054] A calomel electrode is one in which Ag is replaced with mercury (Hg). A saturated calomel electrode (SCE) has an internal solution of saturated KCl aqueous solution, which is +0.242 V relative to the hydrogen electrode. For non-aqueous solutions, a silver wire is placed in a solution of silver nitrate or silver perchlorate (which provide silver ions) dissolved in a non-aqueous solvent together with a supporting electrolyte (silver ion electrode).

[0055] 1, 2, 15, etc., the reference electrode (RE) 111 and the counter electrode (CE) 112 are formed on or arranged in contact with the solid electrolyte 171. Alternatively, the reference electrode (RE) 111 and the counter electrode (CE) 112 are formed or arranged inside the solid electrolyte 171. FIG. 4 is a diagram showing the arrangement and configuration of electrodes (working electrode (WE) 110, counter electrode (CE) 112, and reference electrode (RE) 111) according to an embodiment of the present invention. FIG. 4(a) is a diagram showing the arrangement of electrodes with the liquid injection tube 106 at the center, and FIG. 4(b) is a cross-sectional view taken along line AA' in FIG. 4(a).

[0056] A contact part 125 is disposed at the tip of the solid electrolyte 171. The contact part 125 can be easily detached from the solid electrolyte 171. This allows the head part to be replaced. Various sizes of head parts are available, which can be selected according to the size of the electrode to be used for reduction, etc.

[0057] The solid electrolyte 171 is cylindrical or cubic in shape. The reference electrode 111 and the counter electrode 112 are formed or disposed on the side surface or at predetermined locations of the solid electrolyte 171. The solid electrolyte 171 and the electrolytic solution 124 are disposed so as to be in contact with or face each other.

[0058] The contact portion 125 in contact with the solid electrolyte 171 is filled with the electrolyte 124 or the like. The electrolyte 124 or the like is permeated into glass wool, rayon, polyester, polypropylene, polyethylene, agar, or the like as needed. Preferably, a permeation membrane 172 is disposed or formed on the surface (location) in contact with the thin film 123 or the like that undergoes electrochemical reduction. By disposing the permeation membrane 172, the electrolyte 124 will not leak out.

[0059] 4, a counter electrode (CE) 112 and a reference electrode (RE) 111 are formed or arranged around a solid electrolyte 171. The counter electrode (CE) 112 and the reference electrode (RE) 111 are formed by plating nickel, copper, zinc, or the like.

[0060] The working electrode (WE) 110 is, for example, one electrode of the printed circuit board 109. The working electrode (WE) 110 is connected to a wiring pattern. By connecting the WE terminal of the potentiostat 119 to the wiring pattern, the working electrode (WE) 110 functions as a reduction electrode. 15 is an explanatory diagram of the film thickness measurement device and film thickness measurement method of the present invention, particularly showing the electrode arrangement of the solid electrolyte 171.

[0061] The following embodiment is an example of a method for manufacturing the solid electrolyte 171. The solid electrolyte 171 has a reference electrode 111 and a counter electrode 112 formed therein. The reference electrode 111 is formed inside the solid electrolyte 171.

[0062] Zirconia powder is mixed with various solvents and crushed to form a muddy paste. This is then formed into a sheet. A metal paste that will become the reference electrode 111 or counter electrode 112 is applied to the zirconia sheet. It is preferable to use Ni for the electrode. In this case, Ni paste is applied to the sheet.

[0063] A zirconia sheet that has not been coated with metal paste is placed on top of a zirconia sheet that has been coated with metal paste. The stacked pieces are then pressed together to form a single piece. This process is carried out in a clean room to prevent the inclusion of foreign matter. The integrally molded zirconia block is cut to the desired size. After cutting, it is sintered. Sintering allows the zirconia and internal electrodes to be integrated.

[0064] After firing, the zirconia block is coated with a metal paste that will become the electrodes to electrically connect it to the potentiostat 119. In the case of Ni internal electrodes, Cu paste is applied and then baked at a temperature of around 800 degrees.

[0065] After the electrodes are baked, a two-layer plating of Ni and Sn is applied to the surface. Usually, electrolytic plating is used, with Ni plating improving reliability and Sn plating making soldering easier.

[0066] Counter electrode 112 is formed on the side surface of solid electrolyte 171. Since the surface of counter electrode 112 is Sn-plated, a lead terminal is soldered to it and connected to the CE terminal of potentiostat 119.

[0067] The reference electrode 111 is formed on the upper surface of the solid electrolyte 171. The surface of the reference electrode 111 is Sn-plated, and a lead terminal is soldered to the surface, and the reference electrode 111 is connected to the RE terminal of the potentiostat 119. The positions of the counter electrode 112 and the reference electrode 111 may be interchanged.

[0068] The solid electrolyte 171 is in contact with the electrolytic solution 124. If necessary, a permeation membrane 172 is formed or placed at the portion where the electrolytic solution 124 comes into contact with the thin film 123 or the like where electrochemical reduction takes place. The electrolytic solution 124 is used by permeating agar, glass wool, or the like. The portion in contact with the permeation membrane 172 comes into contact with the electrolytic solution 124, and electrochemical reduction takes place.

[0069] 16, 17, 18, and 19 are explanatory diagrams of the configuration or structure of the solid electrolyte 171 of the present invention. However, for ease of understanding, the drawings are schematic. 16, 17, 18, and 19 are schematic views of the solid electrolyte 171 as viewed from direction C in FIG. 4 (the solid electrolyte 171 as viewed from above).

[0070] 16, 17, 18, and 19, the counter electrode 112 and the reference electrode 111 are shown individually formed for each solid electrolyte 171, but this is not limiting. For example, one counter electrode 112 may be formed or disposed for multiple solid electrolytes 171. The same applies to the reference electrode 111.

[0071] In FIG. 18 and other figures, a space (gap) can be maintained around the reference electrode 111. The electrolyte 124 and the cleaning solution LA can be filled in or passed through the space. For example, the space can be used to function as the liquid injection tube 106 and the liquid drainage tube 107. Furthermore, as shown in FIGS. 7 and 8, the space can be used as the optical path for the incident light 114a2 and the reflected light 114b.

[0072] 16, 17, 18, and 19, the solid electrolyte 171 is illustrated as three or four pieces, but the number is not limited to this. For example, the solid electrolyte 171 may be formed into a thin fiber shape and bundled together to be used, formed, or configured as a head.

[0073] 16, 17, 18, and 19 show only the solid electrolyte 171 portion, but the solid electrolyte 171 also includes the components described in FIGS. 1, 2, 4, etc., such as the electrolyte solution 124 portion and the contact portion 125.

[0074] 16 shows a head for electrochemical reduction formed or configured using a plurality of (for example, four) solid electrolytes 171. A reference electrode 111 is formed or disposed around each solid electrolyte 171. The tip of the head is made of a sponge-like material that is permeated with the electrolyte 124. This allows the electrolyte 124 and the thin film 123 to come into close contact with each other.

[0075] The reference electrode 111 is formed (produced) by applying Cu paste to the area where the reference electrode 111 is to be formed, followed by baking at a temperature of around 800°C. After the reference electrode 111 is baked, a two-layer plating of Ni and Sn is applied to its surface. Electrolytic plating is usually used, but electroless plating may also be used. If necessary, a gold plating film may be formed on the surface. The reference electrode 111 is soldered and electrically connected to the RE terminal of the potentiostat 119 .

[0076] A counter electrode 112 is formed or placed on the upper surface of each solid electrolyte 171. To form (produce) the counter electrode 112, Cu paste is applied to the portion where the counter electrode 112 is to be formed, and then the paste is baked at a temperature of around 800°C. After the counter electrode 112 is baked, a two-layer plating of Ni and Sn is applied to the surface. Electrolytic plating is usually used. Electroless plating may also be used. If necessary, a gold plating film is formed on the surface. The counter electrode 112 is soldered to electrically connect it to the CE terminal of the potentiostat 119.

[0077] The reference electrodes 111 (reference electrodes 111a, 111b, 111c, and 111d) of the solid electrolytes 171 (solid electrolyte 171a, 171b, 171c, and 171d) are made of a conductive material. Therefore, by arranging the solid electrolytes 171 in close contact with each other, the reference electrodes 111 (reference electrodes 111a, 111b, 111c, and 111d) are electrically connected.

[0078] Counter electrodes 112 (counter electrodes 112a, 112b, 112c, 112d) are formed on the respective solid electrolytes 171 (solid electrolyte 171a, solid electrolyte 171b, solid electrolyte 171c, solid electrolyte 171d), and the counter electrodes 112 are electrically connected.

[0079] All of the counter electrodes 112 may be electrically connected, or any one or more of the counter electrodes 112 may be connected to the CE terminal of the potentiostat 119. By changing the positions and number of the counter electrodes 112 connected to the CE terminal, it is possible to set or change the electrochemical reduction capacity and the reduction position.

[0080] The example in FIG. 16 is an example in which a reference electrode 111 (reference electrode 111a, reference electrode 111b, reference electrode 111c, reference electrode 111d) is formed on each solid electrolyte 171 (solid electrolyte 171a, solid electrolyte 171b, solid electrolyte 171c, solid electrolyte 171d).

[0081] FIG. 17 shows an example in which a separate reference electrode 111 is used. The reference electrode 111 is fabricated by cutting metal or by processing a metal plate. The reference electrode 111 is disposed or attached in close contact with each solid electrolyte 171 (solid electrolyte 171a, solid electrolyte 171b, solid electrolyte 171c, solid electrolyte 171d). If necessary, an electrolyte solution 124 (not shown) is filled between the solid electrolyte 171 and the reference electrode 111. Other details are the same as or similar to those in FIG. 16, and therefore a description thereof will be omitted.

[0082] FIG. 18 shows an embodiment in which a head is configured to perform electrochemical reduction using a cylindrical solid electrolyte 171 (solid electrolyte 171a, solid electrolyte 171b, solid electrolyte 171c, solid electrolyte 171d).

[0083] Although the solid electrolyte 171 is illustrated as three or four pieces, the number is not limited to this. For example, the solid electrolyte 171 may be formed into a thin fiber shape and used, formed, or configured by bundling ten or more of these. It may also be in the shape of a thin horn. Around each solid electrolyte 171, a reference electrode 111 (reference electrode 111a, reference electrode 111b, reference electrode 111c, reference electrode 111d) is formed or placed.

[0084] The reference electrodes 111 (reference electrode 111a, reference electrode 111b, reference electrode 111c, and reference electrode 111d) are formed (produced) by applying Cu paste to the area where the reference electrodes 111 are to be formed, and then baking the paste at a temperature of around 800° C. Alternatively, the reference electrodes 111 may be formed by electroless plating.

[0085] After the reference electrodes 111 (reference electrode 111a, reference electrode 111b, reference electrode 111c, and reference electrode 111d) are baked, the surfaces of the reference electrodes 111 are plated with two layers of Ni and Sn. Zn plating may also be formed. If necessary, a gold plating film is formed on the surfaces.

[0086] Reference electrodes 111a, 111b, 111c, and 111d are arranged in close contact with each other, and each reference electrode 111 is electrically connected. A terminal is attached to at least one of the reference electrodes 111 by soldering or pressure welding. The terminal is electrically connected to the RE terminal of the potentiostat 119.

[0087] Counter electrodes 112 are formed or placed on the upper surface of each solid electrolyte 171. The counter electrodes 112 are formed (produced) by applying Cu paste to the area where the counter electrodes 112 are to be formed, and then baking at a temperature of around 800 degrees.

[0088] After the counter electrode 112 is baked, its surface is plated with two layers of Ni and Sn. Electrolytic plating is usually used. If necessary, a gold plating film is also formed on the surface. The counter electrode 112 may also be formed by applying a conductive paste.

[0089] The same applies to the reference electrode 111. The same applies to the other embodiments. A terminal is connected to the counter electrode 112 by soldering or pressure welding, and the terminal is electrically connected to the CE terminal of the potentiostat 119.

[0090] The reference electrodes 111 (reference electrodes 111a, 111b, 111c, and 111d) of the solid electrolytes 171 (solid electrolyte 171a, 171b, 171c, and 171d) are made of a conductive material. Therefore, by arranging the solid electrolytes 171 in close contact with each other, the reference electrodes 111 (reference electrodes 111a, 111b, 111c, and 111d) are electrically connected.

[0091] A plurality of solid electrolytes 171 are stored in a container 105. At the tip of the container, an electrolyte solution 124 and a permeable membrane 172 are attached, as shown in Figures 2, 3, and 4. The above points can also be applied to other embodiments of the present invention.

[0092] Counter electrodes 112 (counter electrodes 112a, 112b, 112c, 112d) are formed on the solid electrolytes 171 (solid electrolyte 171a, solid electrolyte 171b, solid electrolyte 171c, solid electrolyte 171d), respectively, and the counter electrodes 112 are electrically connected. However, all of the counter electrodes 112 may be electrically connected, or any one or more of the counter electrodes 112 may be connected to the CE terminal of the potentiostat 119.

[0093] By changing the position and number of counter electrodes 112 connected to the CE terminal, it is possible to set or change the electrochemical reduction capacity and the reduction position. For example, if counter electrodes 112a and 112c are connected to the CE terminal, electrochemical reduction is achieved in an oblique position. For example, if counter electrodes 112a and 112b are connected to the CE terminal, electrochemical reduction is achieved in an upward position.

[0094] A gap (space) is formed between the container 105 and the solid electrolyte 171. The electrolyte solution 124 and the cleaning solution LA can be filled in or pass through the space. For example, the space can be used to function as the liquid injection tube 106 and the liquid drainage tube 107. Furthermore, as shown in FIGS. 7 and 8, the space can be used as the optical path for the incident light 114a2 and the reflected light 114b.

[0095] The embodiment of FIG. 18 has a head configuration using a cylindrical solid electrolyte 171. However, the present invention is not limited to this. For example, as shown in FIG. 19, the head may be configured using a plate-shaped or planar solid electrolyte 171. Other configurations are the same as or similar to those in FIG. 18, so a description thereof will be omitted.

[0096] FIG. 5 is an explanatory diagram of a potentiostat that drives a working electrode (WE) 110, a reference electrode (RE) 111, and a counter electrode (CE) 112 in the film thickness measurement device of the present invention. In Figure 5, the potentiostat consists of three operational amplifiers 135 and associated resistors 136. The potentiostat has three basic functions. (1) The potential of the working electrode (WE) 110 is regulated relative to the reference electrode. (2) The current flowing through the working electrode (WE) 110 is measured. (3) No current is passed through the reference electrode (RE) 111.

[0097] A current flows between the working electrode (WE) 110 and the counter electrode (CE) 112, and the portion of the potential drop due to the solution resistance caused by the resistance between the counter electrode (CE) 112 and the reference electrode (RE) can be controlled by a potentiostat. However, the resistance between the reference electrode (RE) 111 and the working electrode (WE) 110 cannot be controlled.

[0098] The potentiostat controls the potential by taking into account the potential drop due to the solution resistance between the reference electrode (RE) 111 and the working electrode (WE) 110, so the potential is always lower than the intended value by this drop. This shows that unless an extra potential is applied to compensate for the voltage drop due to the resistance, the potential at which the peak current is obtained cannot be reached.

[0099] In a potentiostat, the potential is controlled by subtracting the potential drop caused by the solution resistance component between the working electrode (WE) 110 and the reference electrode (RE) 111. Therefore, a convenient method called positive feedback is used to add and compensate for this drop.

[0100] The solution resistance between the reference electrode (RE) 111 and the working electrode (WE) 110 is measured in some way and applied to a set potential. The best way to measure the solution resistance is by direct impedance measurement, but this is somewhat complicated, so a simpler method is used.

[0101] The positive feedback of iR compensation is achieved by multiplying the measured current by a certain percentage and adding it to the set voltage. A variable resistor Rpf (137) shown in FIG. 5 is used to add a voltage proportional to the current flowing through the working electrode (WE) 110 to the set voltage Eset.

[0102] The potentiostat circuit described in Fig. 5 corresponds to the potentiostat 119 shown in Fig. 3. The container 105 is filled with a cleaning solution (rinse solution) LA124 or an electrolyte solution LB124, and a circulation fan 122 rotates as necessary to circulate the solution 124, etc.

[0103] For example, a solder, a terminal electrode, or a BGA pad serves as the working electrode (WE) 110. The surfaces of the working electrode (WE) 110, thin film 123, protective film 126, etc. are permeated with an electrolyte 124. A reference electrode 111 and a counter electrode 112 are formed on the solid electrolyte 171. The protective film 126 is removed with a cleaning solution LA before electrochemical reduction.

[0104] The solid electrolyte 171 and the electrolytic solution 124 are in contact with each other. Therefore, when a voltage is applied between the working electrode 110 and the counter electrode 112, the thin film 123 of the working electrode 110 and the like are electrochemically reduced. The amount of electrochemical reduction is controlled by the voltage of the reference electrode 111. The electrolytic solution 124 is agitated by a circulation fan 122.

[0105] A liquid injection tube 106 and a liquid drainage tube 107 are arranged in the container 105. The cleaning liquid LA or the electrolyte solution LB is injected through the liquid injection tube 106. The cleaning liquid LA or the electrolyte solution LB is discharged through the liquid drainage tube 107. Valves (not shown) are formed or arranged in the liquid injection tube 106 and the liquid drainage tube 107 to prevent the liquid from flowing back.

[0106] The surfaces of the working electrode (WE) 110, thin film 123, etc. are filled with an electrolyte 124, and a reduction reaction occurs when a current is passed through the electrode. Since the target substance has a specific reduction potential, the film thickness can be calculated by measuring the time required for reduction.

[0107] In Fig. 3, the reference electrode (RE) 111 and the counter electrode (CE) 112 may be interchanged. The same applies to Figs. 4, 15, 16, 17, 18, and 19. In Fig. 4 and other figures, the counter electrode 112, the reference electrode 111, and the like are shown formed on the surface of the solid electrolyte 171, but this is not limitative. For example, it goes without saying that the counter electrode 112, the reference electrode 111, and the like may be formed inside the solid electrolyte 171, as shown in Fig. 15 and other figures.

[0108] 4, 15, 16, 17, 18, 19, etc., the reference electrode 111 is illustrated as being formed or arranged so as to surround the periphery of the solid electrolyte 171, but the present invention is not limited to this. For example, the counter electrode 112 and the reference electrode 111 may be formed as multiple electrodes and arranged discretely or individually around the solid electrolyte 171. Needless to say, the above points are also applicable to the case where the counter electrode 112 and the reference electrode 111 are formed inside the solid electrolyte 171, as shown in FIG. 15.

[0109] It goes without saying that a portion of solid electrolyte 171 may be cut or polished to form a recess or the like, and counter electrode 112, reference electrode 111, etc. may be formed in the recess or the like. Alternatively, counter electrode 112 and reference electrode 111 may be formed or configured by forming a paste material on solid electrolyte 171, and then drying or sintering the material. The above items, contents, and configurations can be applied to other embodiments of the present invention, and some or all of them can be combined.

[0110] 2 and 4 are explanatory views of a portion of FIG. 1 and are schematic diagrams of a film thickness measurement device of the present invention. As shown in FIG. 2, a ring-shaped contact part 125 is attached to the tip of container 105. Contact part 125 is made of silicone rubber, butyl rubber, polypropylene, nitro rubber, or the like. Contact part 125 is flexible and brings the tip of container 105 into close contact with substrate 109. Electrolyte 124 or the like is filled inside contact part 125. Furthermore, a permeation membrane 172 is disposed as necessary.

[0111] The film thickness measurement device of the present invention deforms the contact portion 125 by pressing it against an area including a sample for which film thickness measurement is to be performed. The deformation of the contact portion 125 prevents leakage of the electrolyte 124 and the like. Furthermore, the permeation membrane 172 is in close contact with the sample (thin film 123, etc.), allowing the electrolyte 124 to be in good contact with the surface of the sample. Therefore, electrochemical reduction can be effectively achieved.

[0112] 2, the contact part 125 is configured to be movable in direction A (upward) and direction B (downward). The size (diameter, etc.) of the contact part 125 is configured to be detachable so that it can be changed according to the sample to be measured. In addition, the solid electrolyte 171 is also configured to be detachable from the main body (not shown) of the film thickness measurement device of the present invention and can be replaced.

[0113] The incident light 114a needs to be focused on the object (electrode 110). By moving in direction A (upward) and direction B (downward), the incident light 114a can be focused on the object (electrode 110).

[0114] 4, a reference electrode 111 is disposed in the solid electrolyte 171. A counter electrode 112 is attached to the upper surface of the solid electrolyte 171 at a position facing the working electrode 110.

[0115] Incident light 114a and reflected light 114b pass through the area filled with electrolyte solution 124. Incident light 114a is irradiated onto thin film 123 and organic film 126. Incident light 114a is reflected by the surface of electrode 110 and becomes reflected light 114b.

[0116] 1 is formed or placed in the container 105. Incident light 114a from a light generator 108 placed outside the container 105 is made to enter the container 105 through the optical window 127. Reflected light 114b passes through the optical window 127 formed or placed in the container 105 and enters a light receiver 117 placed outside the container 105.

[0117] The optical window 127 is preferably made of quartz glass, but may also be made of light lime glass, alkali-free glass, or sodium glass. In particular, when the incident light 114 or the like does not require much spectral transmittance (spectral reflectance) in the ultraviolet wavelength region, the optical window 127 may also be made of a resin material such as polyester, acrylic resin, or polycarbonate resin.

[0118] The working electrode (WE) 110 is, for example, one electrode of the printed circuit board 109. Examples include a bump of a BGA, a connection land with an IC, and a through-hole. However, it is not limited to an electrode. For example, it can be any electrically conductive material, such as a silicon wafer, a steel plate, a plated plate, or a carbon substrate. For example, it can be an oxide. When the solid electrolyte 171 and the electrolytic solution 124 come into contact with each other, ions flow in and out.

[0119] The working electrode (WE) 110 is connected to a wiring pattern. By connecting the WE terminal of a potentiostat 119 to the wiring pattern, it functions as a reduction electrode. A current is applied between the working electrode (WE) 110 and the counter electrode 112, and the working electrode (WE) 110, the thin film 123, or the thin film on the surface, etc., are continuously electrochemically reduced.

[0120] In the container 105, a cleaning liquid (rinse liquid) LA is replaced with an electrolyte solution LB. First, the cleaning liquid (rinse liquid) LA is poured into the container 105 to remove an organic film, an organic solderability preservative (OSP), and the like on the electrode 110. The cleaning liquid (rinse liquid) LA is discharged by turning on and off the electromagnetic valve 101c, and the liquid is discharged as a liquid LC by the pump 102. Thereafter, the cleaning liquid (rinse liquid) LA is discharged from inside the container 105 through the drain pipe 107, and the electrolyte LB 124 is injected into the container 105 through the injection pipe .

[0121] The injection and discharge of the cleaning liquid (rinse liquid) LA and the electrolyte LB is controlled by a liquid volume control unit 120. The electrodes (working electrode (WE), reference electrode (RE), and counter electrode (CE)) are controlled by a potentiostat 119.

[0122] The film thickness measuring device of the present invention has a light controller 118 that measures the film thickness or state of the thin film 123 by irradiating the thin film 123 with light 114a and receiving reflected light 114b.

[0123] This is achieved by measuring the spectral reflectance of the reflected light 114b. Spectral reflectance is the ratio of the spectral density of the reflected radiant or luminous flux to the spectral density of the incident radiation. It is the reflectance for monochromatic radiation and is a function of wavelength.

[0124] The optical structure, such as the film thickness and refractive index of the thin film, is calculated backward (simulated) from the change in the polarization state of light irradiated onto the thin film 123 on the substrate 109. The optical controller 118 models the dielectric function of the thin film from the measurement results of the polarization state of light, etc., and uses the dielectric function to perform theoretical optical calculations (such as simulations) on the change in the polarization state of light.

[0125] The dielectric function of the thin film is determined by numerically optimizing the fitting parameters in the dielectric function model so that the difference between the calculated and experimental results for the polarization state is as small as possible.

[0126] The optical constants (refractive index and extinction coefficient) of the film thickness are calculated from the obtained dielectric function, and by using a model with optical anisotropy, the anisotropy of the optical constants and orientation parameters can be evaluated.

[0127] The dielectric function modeling of the thin film 123 is easy because the constituent materials of the thin film 123 are known or have a similar known composition. Also, the change in the thin film 123 can be continuously monitored by the electrochemical reduction method using a potentiostat 119 or the like.

[0128] Assume that an electrode 110 made of copper (Cu) is formed on a substrate 109, and a thin film 123 (oxide film) is formed on the electrode 110. The light generator 108 has a deuterium lamp and a halogen lamp.

[0129] Deuterium lamps are used in spectroscopy when a continuous spectrum in the ultraviolet region is required. Hydrogen-based plasma "arc" or discharge lamps have high output in the ultraviolet and relatively low output in the visible and infrared. At the same temperature, deuterium-based lamps have a longer life and three to five times the emissivity (intensity) at the far end of the UV range of a typical hydrogen arc lamp.

[0130] Halogen lamps are very small compared to silica bulbs, clear bulbs, and compact fluorescent lamps. Because the lamps are small, the light generator 108 can be made small. They have very high brightness and light properties that make them suitable for use as a point light source. For wavelengths in the ultraviolet region, light emitted from a deuterium lamp is used, and for light in the visible and infrared regions, light emitted from a halogen lamp is used.

[0131] As shown in Figure 6 etc., incident light 114a1 generated by light generator 108 is incident on diffraction grating 116. Diffraction grating 116 is an optical element that separates (disperses) light (white light) containing a mixture of various wavelengths into individual wavelengths. Diffraction grating 116 has a structure in which many parallel slits are arranged at equal intervals. The diffraction grating 116 is not limited to a parallel slit type, but may be a diffraction grating (spectroscope) using a prism.

[0132] The diffraction grating 116 is moved to extract the incident light 114a2 having a wavelength at a predetermined wavelength interval. The incident light 114a2 is focused by the lens 115a, or the direction of the light is adjusted so that it is irradiated onto the electrode 110 surface.

[0133] Incident light 114a2 is irradiated onto thin film 123. Thin film 123 or the material of electrode 110 reflects or absorbs incident light 114a2, and the reflected light 114b is collected by lens 115b and photodetector 117 converts the light into electricity. The reflected light 114b for each wavelength of light has an intensity relative to the incident light 114a2 for each wavelength. From this intensity for each wavelength, the spectral reflectance can be measured or obtained.

[0134] From the spectral reflectance, the optical structure, such as the film thickness and refractive index, of the thin film 123 on the substrate 109 is calculated inversely. The optical controller 118 models the dielectric function of the thin film from the measurement results of the polarization state of light, etc., and uses the dielectric function to perform theoretical optical calculations on changes in the polarization state of light to determine the film thickness of the thin film 123, etc.

[0135] In the spectroscopic film thickness measurement method, it is necessary to eliminate the influence of reflected light from the back surface of the object to be measured. However, in the film thickness measurement device of the present invention, the object to be measured is composed of copper electrode 110, etc., and all of the incident light 114a is reflected or absorbed by copper electrode 110, etc., so there is little influence from reflected light.

[0136] 12 shows an example in which the spectral reflectance of electrode 110 was measured using the spectral film thickness measurement method. Electrode 110 is made of copper (Cu). This is an example in which the spectral reflectance of Cu in electrode 110 was measured using the spectral film thickness measurement method. As shown by the dotted line, Cu has high reflectance in the long wavelength region and good reflectance in the near infrared region of 700 nm.

[0137] The solid line shows the spectral reflectance when copper oxide (CuO) is formed as thin film 123 on electrode 110. Copper oxide (CuO) has low reflectance in the visible light range and high transmittance in the long wavelength range.

[0138] The thickness of copper oxide (CuO) can be calculated by simulation using an optical model and spectral reflectance of copper oxide (CuO). Therefore, by measuring the spectral reflectance (spectral transmittance) using the spectral film thickness measurement method, it is possible to estimate or determine the presence or absence of the material being measured and its film thickness.

[0139] The thin film 123 is an oxide film or an organic film and is optically transparent. The electrode 110 is a metal film such as copper, and therefore reflects the incident light 114a2. The thin film 123 exhibits a spectral transmittance (spectral reflectance) according to the refractive index and attenuation coefficient of the material that constitutes the thin film 123.

[0140] The refractive index of the cleaning solution (or rinse solution) LA or the electrolyte LB is close to 1.33, which is the refractive index of water. If the oxide of the thin film 123 is copper dioxide (CuO2), the refractive index is 2.17. The optical model of copper dioxide is known, and simulation fitting for film thickness calculations is easy.

[0141] If the oxide of the thin film 123 is copper oxide (CuO), the refractive index is 2.63. The optical model of copper oxide is known, and simulation fitting in film thickness calculation is easy.

[0142] The film thickness of the thin film 123 can be calculated by defining an optical model assuming that the components of the thin film 123 are copper dioxide and copper oxide, and performing a simulation for film thickness calculation.

[0143] Copper dioxide (CuO2) and copper oxide (CuO) have a large difference in refractive index from the cleaning solution (rinse solution) LA or the electrolyte solution LB 124, and the reflectance of the copper of the electrode 110 is also relatively high, so the intensity of the reflected light 114 is also large, enabling stable measurements. This optical film thickness measurement method is called spectroscopic film thickness measurement.

[0144] When the thin film 123 is not filled with cleaning liquid (rinse liquid) LA or electrolyte LB (air, nitrogen), the difference between the refractive index of 1.0 and the refractive index of copper dioxide (CuO2) is 2.17, and the refractive index of copper oxide (CuO) is 2.63, so the refractive index difference is large and stable measurement can be achieved.

[0145] When the thin film 123 is an oxide of silicon (Si) used in semiconductor elements, etc., the refractive index of silicon dioxide (SiO2) is 1.46, and the refractive index of silicon monoxide (SiO) is 1.90. Although the difference in refractive index with the cleaning liquid (rinse liquid) LA or the electrolyte LB is small, the optical models for silicon dioxide (SiO2) and silicon monoxide (SiO) have been established, so the film thickness can be calculated with high accuracy.

[0146] The spectroscopic film thickness measurement method using the reflected light 114b and the electrochemical reduction method using a potentiostat can be performed simultaneously. The film thickness of the thin film 123 can be measured or obtained from the reflected light 114b, and the film thickness can also be measured or obtained by the electrochemical reduction method. By combining the two methods, the film thickness and material of the thin film 123 can be measured or determined with high accuracy.

[0147] The spectroscopic film thickness measurement method can achieve high film thickness accuracy if an optical model of the thin film 123 can be constructed with high accuracy. However, if the thin film 123 is composed of two layers of copper dioxide (CuO) and copper oxide (CuO), for example, or is composed or formed of a mixture of copper dioxide (CuO) and copper oxide (CuO), it cannot be modeled with a high-accuracy optical model. Therefore, the film thickness accuracy obtained by calculation or simulation decreases.

[0148] The electrochemical reduction method is controlled by a potentiostat, a constant current is applied to cause a reduction reaction at the electrode (WE), and the change in potential E (V) over time is recorded or measured. The amount of material forming the thin film 123 can be quantitatively measured or understood from the recorded or measured plateau. However, it is difficult to quantitatively measure or understand the film thickness.

[0149] The present invention can quantitatively measure the film thickness of the thin film 123 etc. by using a spectroscopic film thickness measurement method. Also, the forming material and the amount of forming material of the thin film 123 etc. can be quantitatively measured by using an electrochemical reduction method.

[0150] Therefore, the spectroscopic film thickness measurement method can quantitatively measure the film thickness of the thin film 123, etc. The synergistic effect of the spectroscopic film thickness measurement method and the electrochemical reduction method allows the film thickness, amount of forming material, and forming material of the thin film material 123, etc. to be measured quantitatively and accurately.

[0151] Since the spectroscopic film thickness measurement method and the electrochemical reduction method can be performed simultaneously, it is possible to measure the film thickness of the thin film 123 while measuring the potential (V) of the thin film 123, etc., and therefore it is possible to accurately grasp the material being reduced and the change points of that material. By constantly or at appropriate times feeding back the determined change points to the optical model of the spectroscopic film thickness measurement method, it is possible to realize highly accurate film thickness calculations (film thickness simulations).

[0152] Before the spectroscopic film thickness measurement method, the cleaning liquid LA is filled into the container 105, and the organic film 126 is removed. This allows the electrochemical reduction method to be performed satisfactorily. Furthermore, since the film thickness of the organic film 126 can be measured by the spectroscopic film thickness measurement method, the time required to fill the container 105 with the cleaning liquid LA can be accurately estimated.

[0153] Fig. 6 is a diagram illustrating the configuration and explanation of a spectroscopic film thickness measurement method for measuring the film thickness of an object (such as a thin film 123). In Fig. 6, the lenses 115 (lenses 115a and 115b) are shown as concave mirrors, but this is not limited to this and they may be configured as convex lenses, etc. The focusing optical system may also be configured by combining concave lenses and convex lenses, etc. Concave mirrors may also be used.

[0154] As an example, as shown in FIG. 13, an electrode 110 made of copper (Cu) is formed on a substrate 109, and a thin film 123 (such as an oxide film, thin film 123a, thin film 123b) and an organic film 126 are formed on the electrode 110.

[0155] The light generator 108 includes a deuterium lamp and a halogen lamp. The deuterium lamp is mainly responsible for generating light in the ultraviolet wavelength range, while the halogen lamp is mainly responsible for generating visible light and infrared light.

[0156] The incident light 114a1 generated by the light generator 108 is incident on a diffraction grating (including a prism, etc.) 116. The diffraction grating (including a prism, etc.) 116 is an optical element that separates light (white light) that is a mixture of various wavelengths into individual wavelengths. The diffraction grating 116 has a structure in which many parallel slits are arranged at equal intervals.

[0157] Light 114a1 incident on diffraction grating 116 is split into wavelengths by diffraction grating 116. The split light 114a2 has its direction changed by lens or reflecting mirror 115a and illuminates thin film 123 or the like. By moving the diffraction grating 116 or by moving the position at which light is incident on the diffraction grating 116, incident light 114a2 having wavelengths spaced apart by a predetermined wavelength is extracted.

[0158] The incident light 114a2 does not have to be light that is continuously changed within a predetermined wavelength range. For example, the wavelength may be fixed at 630 nm, and the intensity of the reflected light 114b may be continuously monitored. The intensity of the reflected light 114b can be used to determine changes in film thickness. Therefore, the spectral reflectance of the film thickness measuring device of the present invention may be measured or acquired at a constant wavelength. The position of the lens 115 or the position of the substrate 109 is changed to adjust the position so that the incident light 114a2 is focused on the target (electrode 110).

[0159] Incident light 114a2 is irradiated onto thin film 123. Thin film 123 or the material of electrode 110 reflects or absorbs incident light 114a2, and the reflected light 114b is collected by lens 115b and converted into electricity by photodetector 117.

[0160] In the spectral film thickness measurement method, a reference base reflectance must be measured in advance. The reflectance is measured as a percentage of the base reflectance (100%).

[0161] To measure the base reflectance, a reflector with a highly reflective film made of silver, aluminum, or the like is placed at the position of electrode 110 (placed at the focal position of incident light 114a), and the reference spectral reflectance is measured. The reflectance of reflected light 114b is measured relative to the measured reference spectral reflectance. The film thickness of thin film 123, etc. is calculated using the measured spectral reflectance characteristics and an optical model of the thin film 123, etc. being measured. In FIG. 6, the incident light 114a is incident on the thin film 123 etc. from an oblique direction, but the film thickness measuring device of the present invention is not limited to this. 7 and 8 show an optical system in which incident light 114a is incident on a plane of a thin film 123 or the like in a perpendicular direction and reflected light 114b is extracted in a perpendicular direction.

[0162] 7, incident light 114a1 from light generator 108 has its direction changed by mirror 128, passes through half mirror 151, and is incident perpendicularly on thin film 123. Incident light 114a2 passes through the center of injection tube 106.

[0163] The incident light 114a2 is reflected by the thin film 123, and the reflected light passes through the center of the liquid inlet tube 106 (or the liquid outlet tube 107, etc.) again. The reflected light 114b is reflected by the reflecting surface of the half mirror 151 and enters the light receiver 117. FIG. 8 shows an embodiment in which a polarizing beam splitter 152 is used in place of the half mirror 151 in FIG.

[0164] The incident light 114a1 from the light generator 108 is changed in direction by the mirror 128 and passes through the light separation surface (polarization surface) 153 of the polarizing beam splitter 152, whereby the incident light 114a2 becomes polarized light and is incident perpendicularly on the thin film 123. The incident light 114a2 passes through the center of the injection tube 106.

[0165] Incident light 114a2 is reflected by thin film 123, and the reflected light 114b, whose polarization has been disturbed, passes again through the center of infusion tube 106. Reflected light 114b is reflected by light separation surface (polarization surface) 153 of polarizing beam splitter 152 and enters photodetector 117. Use of polarizing beam splitter 152 allows the light irradiation section of the device to be configured compactly.

[0166] 7 and 8, the incident light 114a2 and the reflected light 114b pass through the liquid injection tube 106, but this is not limiting. The incident light 114a2 may be incident from above the thin film 123, and the reflected light 114b may pass through a location other than the drain tube 107 and the liquid injection tube 106.

[0167] 9 is an explanatory diagram of a film thickness measurement method using electrochemical reduction. As an example, a case is shown in which tin-containing solder is formed on an electrode or the like, and a thin film 123 made of tin oxide (tin oxide SnO, tin dioxide SnO2) is formed (generated) on the solder surface. The solder corresponds to the electrode 110. The solder 110 is used as the working electrode 110, and a current is supplied between the working electrode 110 and the counter electrode 112.

[0168] In Figure 9, the horizontal axis represents time. For ease of explanation and understanding, the time is expressed in minutes (min). The vertical axis represents potential (V). The reduction time varies depending on the magnitude of the constant current applied.

[0169] A reduction reaction occurs when the surface of the solder 110 is filled with electrolyte 124 and a small current is passed through the solder using the solder as the electrode 110. Since each substance has or changes its own reduction potential (V), the film thickness can be calculated (estimated) by measuring the time required for reduction.

[0170] The electrochemical reduction method is controlled by a potentiostat 119, a constant current is applied to the electrode (WE) to cause a reduction reaction, and the time change of the potential E (V) is recorded. The amount of material forming the thin film 123 can be quantitatively measured from the recorded plateau potential.

[0171] Figure 9 shows an example of measuring the Sn surface of solder. The vertical axis is potential (E (V)) and the horizontal axis is time (min). The potential on the vertical axis differs depending on whether it is in relation to a calomel electrode or a silver (Ag) electrode. It also differs depending on the electrolyte (for example, AgCl). The potential E (V) can be corrected depending on the type of electrolyte and electrode. The first plateau of A is at a potential of −0.85 to −1.06 V and is estimated to be SnO. When the reduction time is 30 sec (0.5 min), the film thickness is 11 Å.

[0172] The second plateau at B has a potential of -1.06 to -1.18 V and is presumed to be SnO2. When the reduction time is 100 seconds, the film thickness is 15 Å. The potential at C is -1.2 V, which is presumed to be the hydrogen evolution potential of Sn. It is estimated that in the first plateau at A, SnO is converted to Sn, and in the first plateau at B, SnO2 is converted to Sn.

[0173] The electrochemical reduction method used in the film thickness measurement device of the present invention has a short measurement time and low cost. It is also possible to distinguish or discriminate between oxide films with different valences. Examples of metal oxide films to be measured include oxides of Cu, Ag, Sn, Si, and solder. Examples of metal film thicknesses include oxides of Si, Ni, Cu, Ag, Sn, Au, and Ag.

[0174] 11 is an explanatory diagram showing the state of electrochemical reduction when the thin film 123 of the present invention is covered with an organic film 126. The organic film 126 may be an organic film caused by contamination, or an organic solderability preservative (OSP) may be formed on the electrode.

[0175] For example, there is the heat-resistant water-soluble preflux (OSP) used in the manufacturing process of printed wiring boards (PWB). It has excellent solder wettability for high temperatures and multiple mounting with lead-free solder. Many types of OSP are sold by manufacturers.

[0176] As an example, two types of OSPs (OSP1 and OSP2) are shown in Figure 11. In Figure 11, Cu1 indicates the potential change of an electrode made of Cu when there is no OSP1 (when OSP1 is removed). Cu2 indicates the potential change of an electrode made of Cu when there is no OSP2 (when OSP2 is removed).

[0177] In Figure 11, OSP1 has almost no plateau. OSP2 has a first plateau, but the redox potential remains constant for 70 seconds or more. In the case of Cu alone, there is no plateau with large changes, and the change is gradual. The solid line (Cu2) has a plateau step. The short dotted line (Cu1) also has a plateau step. The solid line (Cu2) and the short dotted line (Cu1) have different times at which the plateau flattens.

[0178] The first plateau is presumed to be Cu2O, and the second plateau is presumed to be CuO. For Cu2, it becomes constant over 40 seconds, presumed to be the reduction potential of Cu2. For Cu1, it becomes constant over 60 seconds, presumed to be the reduction potential of Cu1.

[0179] As shown in Figure 11, if OSPs (OSP1, OSP2) are formed, it is highly likely that the Cu oxide film below the OSPs cannot be measured. Removing OSP1 exposes the thin film 123, allowing for accurate measurement of the redox potential. Similarly, removing OSP2 exposes the thin film 123, allowing for accurate measurement of the redox potential. Therefore, in order to measure the thickness of the thin film 123, which is made of an oxide film, it is necessary to remove the OSPs.

[0180] The film thickness measurement device of the present invention can remove an organic film 126 such as OSP by pouring a cleaning liquid LA into a container 105. Furthermore, the presence or absence of an organic film (organic protective film OSP) 126 and the film thickness thereof can be measured by a spectroscopic film thickness measurement method.

[0181] In the present invention, before the cleaning liquid LA is poured into the container 105, the presence or absence of the organic film 126 and the estimated film thickness of the organic film are measured or obtained by a spectroscopic film thickness measurement method. The estimated film thickness is used when the optical model of the organic film 126 is unclear. When the optical model is known, the film thickness can be determined with high accuracy.

[0182] If the organic film 126 is not observed by the spectroscopic film thickness measurement method, the cleaning solution LA is not poured into the container 105, but the electrolyte solution LB is poured instead. Before pouring the electrolyte solution LB, the presence or absence of the thin film 123 and the estimated film thickness of the thin film 123 are measured or obtained.

[0183] If an organic film 126 is present (organic film 126 is present), cleaning liquid LA is poured in. The change in film thickness (spectral reflectance) of the organic film 126 is monitored or acquired by a spectroscopic film thickness measurement method. When pouring the cleaning liquid LA, the circulation fan 122 is operated as needed to circulate the cleaning liquid LA inside the container 105. In addition, the cleaning liquid LA is poured and drained.

[0184] The change in the film thickness (spectral reflectance) of the organic film 126 is monitored or acquired. In the spectral film thickness measurement method, the presence or absence of the organic film 126 and the change in film thickness can be determined from the change in the spectral reflectance. The cleaning liquid LA does not remove the thin film 123 made of an inorganic material, but can remove the organic film 126 made of an organic material.

[0185] In the film thickness measurement device and film thickness measurement method of the present invention, if necessary, the OSP is removed with cleaning solution LA, and then electrochemical reduction is performed. Simultaneously or sequentially, spectroscopic film thickness measurement is also performed.

[0186] Note that cleaning performance can be improved by applying ultrasonic waves (cleaning and stirring by ultrasonic vibration) during cleaning with the cleaning solution LA and during electrolysis with the electrolytic solution 124. Ultrasonic waves may be applied to the container 105, but applying them to the substrate 109 is more effective.

[0187] If the OSP is applied thickly, it may cause problems in measuring the film thickness of the thin film 123, but stable measurements can be made by using cleaning solution LA and implementing spectroscopic film thickness measurement.

[0188] FIG. 10 shows an example of an electrochemical reduction method using an electrolytic solution (boric acid, sodium tetraborate, potassium chloride) at a constant current (30 μA / cm 2 ) or in this example, a reduction reaction was caused on the surface of the electrode 110 at a predetermined current, and the change in potential over time was recorded.

[0189] A silicone rubber pad with a diameter of 3.5 mm is used for the contact part 125. The contact part 125 is moved in the direction A or B as shown in Figure 2 to adjust the state of contact with the substrate 109 and the focal position in the spectroscopic film thickness measurement method.

[0190] The times indicated in Fig. 10 indicate the time left in the reflow. It is assumed that the longer the time left in the reflow, the thicker the oxide film (thickness of the thin film 123) formed on the electrode 110. As shown in the graph in Fig. 10, the plateau time is longest at 30 minutes and shortest at 1 minute.

[0191] The film thickness measurement device of the present invention performs spectroscopic film thickness measurement simultaneously with or sequentially after the electrochemical reduction method. The spectroscopic film thickness measurement method can measure the film thickness of the thin film 123. When the thin film 123 is composed or formed of a mixture or stack of CuO, CuO, and Cu portions, the state of the stack or mixture can be determined as a difference in spectral transmittance using the spectroscopic film thickness measurement method. However, it is difficult to determine the film thickness of each layer (e.g., CuO, CuO).

[0192] With the electrochemical reduction method, the first and second plateaus can be observed and the time for each plateau can be measured, making it possible to determine the composition of the constituent materials of each layer, as shown in the graphs in Figures 9 and 11. Knowing the composition of the constituent materials allows us to improve or determine the accuracy of the optical model for each layer in the spectroscopic film thickness measurement method, making it possible to separate each layer and form film thicknesses.

[0193] For example, if the thin film 123 is composed of an Sn-related layer, in the electrochemical reduction method, the thickness of SnO is determined from the time required for the potential range of -0.85 V to -1.05 V (first plateau), and the thickness of SnO2 is determined from the time required for the potential range of -1.05 V to -1.15 V (second plateau). When all the oxide film is removed, the final hydrogen evolution potential of Sn is approximately -1.30 V.

[0194] The first plateau can be understood to be amorphous SnO, and the second plateau to be crystalline SnO2 or a mixed layer of SnO and SnO2, etc. The thickness of each layer can be determined by spectroscopic film thickness measurement using an optical model of each constituent material.

[0195] 13 and 14 are explanatory diagrams of the film thickness measurement method of the present invention. Fig. 13 is a structural diagram of a thin film 123, etc. for explanation. Fig. 14 is a flowchart of the film thickness measurement method of the present invention.

[0196] As shown in FIG. 13, thin films 123a and 123b made of, for example, oxide films are formed on electrode 110 on substrate 109, and an organic film 126 is formed on thin film 123a.

[0197] In the spectral film thickness measurement method, a reference base reflectance must be measured in advance. The reflectance is measured as a percentage of the base reflectance (100%).

[0198] In order to measure the reflectance that serves as the base for the reflectance by the spectroscopic film thickness measurement method, a reflector having a highly reflective film made of silver (Ag), aluminum (Al), etc. is measured. The reflectance of the reflected light 114b of the thin film 123, etc. is measured using the reflectance of the reflector as a baseline (S01).

[0199] To measure the reflectance of the reflector, the position of the contact portion 125 is adjusted so that the focal position of the incident light 114a is adjusted to be on the measurement target (thin film 123, etc.) (S02).

[0200] Next, incident light 114a is irradiated onto organic film 126, and reflected light 114b is measured. At this time, cleaning liquid LA is not poured into container 105. However, this does not apply if reflected light 114b can be measured by the spectroscopic film thickness measurement method after pouring cleaning liquid LA and before organic film 126 peels off or the like. In the spectroscopic film thickness measurement method of the present invention, incident light 114a is irradiated onto the organic film 126, etc., and reflected light 114b from the organic film 126, etc. is measured (S03).

[0201] The reflectance of the reflected light 114b is measured relative to the measured reference spectral reflectance. The film thicknesses of the organic film 126, thin film 123, etc. are calculated using the spectral reflectance characteristics of the reflected light 114b measured and optical models of the organic film 126, thin film 123, etc. to be measured (S04). Step S04 and the like are not necessary if the organic film 126 is not formed. Also, if it is only necessary to determine whether or not the organic film 126 is present, calculation of the film thickness of the organic film 126 is not necessary.

[0202] If an organic film 126 has been formed, or if there is a contaminant film corresponding to the organic film 126, the organic film 126 or the like is removed. In order to remove the organic film 126, a cleaning liquid LA is poured into the container 105. When the cleaning liquid LA is poured (S05), the film thickness calculation in the spectroscopic film thickness measurement method is performed by corresponding the refractive index of air (atmospheric refractive index 1.0) to the refractive index of the cleaning liquid LA and correcting the calculation. By pouring in the cleaning liquid LA (S05), the organic film 126 is dissolved by the cleaning liquid LA or peeled off and removed from the thin film 123. The state of dissolution or peeling of the organic film 126 can be detected by the spectroscopic film thickness measurement method of the present invention.

[0203] The film thickness measurement method of the present invention is not limited to film thickness measurement; the method of removing thin film 123 and organic film 126 (method of removing thin film, etc., thin film, etc. removal device) also falls within the scope of the technical concept of the present invention. Since the organic film 126 is not detected by the spectroscopic film thickness measurement method, it can be confirmed that the organic film 126 has been removed from the thin film 123 .

[0204] Next, or continuously, incident light 114a is irradiated and reflected light 114b is measured (S06). Since the structure or composition of thin film 123 is estimated by an optical model, it is difficult to accurately simulate it using the spectroscopic film thickness measurement method. Furthermore, it is often unclear how many thin film layers thin film 123 is made up of. Furthermore, thin film 123 may be made up of a mixture of materials with multiple compositions.

[0205] 13, the thin film 123 is described as being formed or configured of a thin film 123a and a thin film 123b. Film thickness data of the thin film 123a and the thin film 123b obtained by calculation or simulation are calculated (S07). In addition, the film thickness data of the thin film 123a and the thin film 123b are recorded.

[0206] In the electrochemical reduction method of the present invention, the type, composition, and chemical symbol of the material constituting the thin film 123 can be determined from the plateau potential, the number of plateaus, and the plateau time. An optical model can be determined from the type, composition, and chemical symbol of the material constituting the thin film 123. The optical model and the film thickness calculated by the spectroscopic film thickness measurement method are taken into consideration. Furthermore, by performing correction, the film thickness, composition, etc. of the thin films 123a and 123b can be determined with high accuracy.

[0207] Next, the cleaning liquid LA is discharged from the drain pipe 107, and the electrolyte LB is injected into the container 105 from the liquid injection pipe 106 (S08). At this time, the circulation fan 122 rotates so as to discharge the cleaning liquid LA from the drain pipe 107. In the steps from S08 onwards, both or either of the electrochemical reduction method of the present invention and the spectroscopic film thickness measurement method of the present invention are carried out alternately or simultaneously. The spectroscopic film thickness measurement method of the present invention is Sa1 to Sa3. The electrochemical reduction method of the present invention is Sb1 to Sb3.

[0208] In the spectroscopic film thickness measurement method of the present invention, incident light 114a is irradiated and reflected light 114b is measured (Sa1). The incident light 114a is focused on the thin film 123. The light reflected by the thin film 123 is incident on the photodetector 117 as reflected light 114b (Sa1). The incident light 114a and reflected light 114b travel through the solution 124 as shown in FIGS. 2 and 13. In addition, the electrochemical reduction method of the present invention is carried out simultaneously with or at an appropriate time to the spectroscopic film thickness measurement method (Sb1).

[0209] The film thicknesses of thin films 123a and 123b are calculated using the spectroscopic film thickness measurement method (Sa2). Using the electrochemical reduction method, thin film 123b is detected or obtained from the potential and time of the first plateau (sb2). Next, thin film 123a is detected or obtained from the potential and time of the second plateau (Sb3).

[0210] The end of the first plateau in the electrochemical reduction method means that the thin film 123b has been removed. Therefore, the film thickness measured by the spectroscopic film thickness measurement method of the present invention corresponds to the film thickness of the thin film 123a.

[0211] When thin film 123b and thin film 123a remain, the spectral reflectance of reflected light 114b due to thin film 123b and thin film 123a is measured (Sa2).When thin film 123b is removed and thin film 123a remains, the spectral reflectance of reflected light 114b due to thin film 123b is measured (sa3).

[0212] Therefore, the plateau potential and time state in the electrochemical reduction method can be used to determine the material composition of the thin films 123a and 123b and the remaining state of the thin film 123. If the material composition of the thin films 123a and 123b is known, an optical model can be constructed, and accurate film thickness calculations can be performed using the spectroscopic film thickness measurement method (sa2, Sa3).

[0213] Simply irradiating the thin film 123 with incident light 114a and measuring the reflected light 114b results in an estimation of the optical model of the structure or composition of the thin film 123. With the electrochemical reduction method, the composition, structure, and chemical model of each thin film can be determined from the number of plateaus, potential, and time, such as the potential and time of the first plateau and the potential and time of the second plateau. By alternately or simultaneously using both the electrochemical reduction method and the spectroscopic film thickness measurement method of the present invention, or one of them, the film thickness, composition, etc. of each thin film 123 can be determined or obtained with high accuracy. The spectroscopic film thickness measurement method and the spectroscopic film thickness measurement method exhibit a synergistic effect.

[0214] The above-described embodiments and the accompanying drawings are examples of preferred embodiments, and the embodiments described in this specification, the drawings, etc. can be combined with each other in part or in whole. Furthermore, the present invention can be substituted, modified, and changed in various forms within the scope of the technical idea of ​​the present invention described in the claims. [Industrial Applicability]

[0215] The present invention can quantitatively measure oxide films on solder and copper foil of printed circuit boards. Surface oxide films are factors that govern corrosion resistance, solder adhesion, element reliability, etc., so their composition and film thickness can be evaluated. The present invention contributes to industrial development. [Explanation of symbols]

[0216] 101 Solenoid valve 102 Pump 103 Defoamer 104 Liquid Tank 105 Container 106 Liquid injection tube 107 Drainage tube 108 Light Generator 109 PCB 110 electrode (working electrode (WE)) 111 Reference electrode (RE) 112 Counter electrode (CE) 114a Incident light 114b Reflected light 115 Lens 116 Diffraction Grating 117 Receiver 118 Optical Controller 119 Potentiostat 120 Liquid volume control section 121 Controller 122 Circulation Fan 123 Thin films (organic films, oxide films) 124 Solutions (electrolytes, cleaning solutions) 125 Close contact area 126 Organic film 127 Light Window 128 Mirror 135 operational amplifiers 136 Resistor 151 Half Mirror 152 Polarizing Beam Splitter 153 Light separation plane 161 Level detector 162 Solution reservoir 171 Solid electrolyte 172 Osmotic membrane

Claims

1. A film thickness measuring device for determining the film thickness of a thin film on a conductor, comprising: a counter electrode (CE) and a reference electrode (RE) disposed or formed in the solid electrolyte; an electrolytic material disposed between the thin film and the solid electrolyte; A film thickness measuring device characterized in that the conductor is used as a working electrode (WE) and electrochemical reduction is carried out to determine the film thickness of the thin film.

2. A film thickness measuring device for determining the film thickness of a thin film on a conductor, comprising: a counter electrode (CE) and a reference electrode (RE) disposed or formed in the solid electrolyte; an electrolytic material disposed between the thin film and the solid electrolyte; a current circuit that applies a constant current between the conductor as a working electrode (WE) and the counter electrode (CE); A film thickness measuring device comprising a measuring circuit for measuring a reduction potential resulting from electrochemical reduction.

3. A film thickness measuring device for determining the film thickness of a thin film on a conductor, comprising: a counter electrode (CE) and a reference electrode (RE) disposed or formed in the solid electrolyte; a cleaning device for filling a cleaning liquid between the thin film and the solid electrolyte; a filler for filling an electrolytic solution between the thin film and the solid electrolyte; A film thickness measuring device characterized in that the conductor is used as a working electrode (WE) and electrochemical reduction is carried out to determine the film thickness of the thin film.

4. A film thickness measuring device for determining the film thickness of a thin film on a conductor, comprising: a counter electrode (CE) and a reference electrode (RE) disposed or formed in the solid electrolyte; The solid electrolyte is disposed in contact with a material or a permeable membrane impregnated with an electrolytic solution, A film thickness measuring device characterized in that the conductor is used as a working electrode (WE), a material or a permeated membrane permeated with the electrolyte is placed in contact with the thin film, and the film thickness of the thin film is determined by performing electrochemical reduction.

5. A film thickness measuring device for determining the film thickness of a thin film on a conductor, comprising: a counter electrode (CE) and a reference electrode (RE) disposed or formed in the solid electrolyte; an electrolytic material disposed between the thin film and the solid electrolyte; a light generator that generates incident light to irradiate the thin film; a light receiver that receives light reflected by the thin film; A film thickness measuring device characterized in that the conductor is used as a working electrode (WE) and electrochemical reduction is carried out to determine the film thickness of the thin film.

6. A film thickness measuring device as described in claim 1, claim 2, claim 3, claim 4 or claim 5, characterized in that the solid electrolyte is stabilized zirconia.

7. A film thickness measuring device as described in claim 1, claim 2, claim 3, claim 4 or claim 5, characterized in that the reference electrode (RE) is formed within the solid electrolyte.

8. Further comprising an adhesive portion disposed between the periphery of the thin film and the solid electrolyte, 5. The film thickness measuring device according to claim 3, wherein the electrolyte is disposed or filled in the contact portion.

9. Further comprising an adhesive portion disposed between the periphery of the thin film and the solid electrolyte, 5. The film thickness measuring device according to claim 3, further comprising: an injection pipe for injecting the electrolytic solution into the contact portion; and a drain pipe for discharging the electrolytic solution from the contact portion.

10. A film thickness measuring device as described in claim 1, claim 2, claim 3, claim 4 or claim 5, characterized in that the solid electrolyte is composed of a plurality of solid electrolyte parts, and the counter electrode (CE) and the reference electrode (RE) are arranged or formed in the solid electrolyte parts.

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