JP2008252001A - Method of manufacturing thin-film capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a capacitor capable of maintaining high electrostatic capacity and improving uniformity in the electrostatic capacity simultaneously. <P>SOLUTION: A ground metal layer 11 is formed in a part, where a trench should be formed, on a substrate 10. A coupon metal layer 13 is formed on the part. An electrode metal layer 14 is buried between the coupon metal layers 13 by plating. The surfaces of coupon metal layer 13 and electrode metal layer 14 are polished for exposing the coupon metal layer 13. The coupon metal layer 13 is removed for forming a trench 14a corresponding to the pattern. In the trench 14a, a dielectric film 16 and the electrode metal layer 14 are laminated successively, thus obtaining a thin-film capacitor 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a thin film capacitor, and more particularly to a method for manufacturing a trench type thin film capacitor.

  Various types of electronic components of surface mounting type are mounted on internal circuits of electronic devices such as computers and portable terminals. Recently, in order to meet the demand for higher performance and miniaturization of electronic devices, there is an urgent need for further miniaturization and thinning (thin film) of various electronic components regardless of active elements and passive components. Examples of such thin-film electronic components include thin-film capacitors, thin-film inductors, thin-film LC composite components, thin-film lumped constant devices, thin-film distributed constant devices, and thin-film multilayer composite components that utilize a thin-film formation process. .

Among these, as one of methods for achieving miniaturization and thinning while increasing the capacitance per unit volume (volume) of the thin film capacitor, a trench (underlying step structure) is formed in the base, and the trench is formed in the trench. A method of forming a thin film capacitor has been proposed (see Patent Document 1). According to this method, since the electrode surface area of the thin film capacitor is increased as compared with the case where the thin film capacitor is formed on a smooth substrate, the capacitance can be increased.
JP-A-6-325970

  In such a trench-type thin film capacitor, by increasing the trench aspect ratio (AR: depth / width), the electrode surface area per unit area is further increased, thereby further increasing the capacitance of the capacitor. In principle it is possible. In general, as a method of forming a trench, a method of forming a trench using a dicing saw, an electron beam or the like on a metal base serving as an electrode as described in Patent Document 1 above, a trench pattern is formed on the base serving as an electrode. For example, a method of forming a given resist and forming a trench by dry etching or wet etching using the resist as a mask, and guaranteeing processing accuracy and shape stability in miniaturization to suppress variation in capacitance. From the viewpoint, trench formation by etching is preferable.

  However, when trying to form a trench with a high aspect ratio, it is difficult to form a trench having a uniform width and depth even if anisotropic etching is used in addition to dry and wet. Substrate of thin film capacitor finally formed due to large variation in trench shape between provided trenches or within a substrate or substrate surface such as a wafer (hereinafter collectively referred to as “substrate surface” or “substrate surface”) This results in non-uniform capacitance in the plane.

  In order to eliminate such an inconvenience, a method using a plating technique can be considered as a low-cost method that can form a trench having a high aspect ratio with higher accuracy than a method of etching a metal substrate. In this method, after applying a resist to a portion where a trench is to be formed, a trench pattern is formed in the resist by photolithography, and a non-resist formation region is filled with a metal layer to be a lower electrode by plating, and then the resist is removed. Thus, a lower electrode having a trench is formed.

  As described above, in order to improve the uniformity (in-plane uniformity) of the capacitance of the thin film capacitor in the substrate plane, it is required to make the trench shape (width, depth) uniform in the substrate plane. The resolution of resist patterning by photolithography in recent years is extremely high, and sufficient uniformity can be achieved in the width of the trench and hence the line width of the lower electrode embedded in the trench. On the other hand, since it is difficult to directly form a metal layer having a uniform height on the substrate surface by plating, the surface of the metal layer together with the resist is polished by CMP after the metal layer is formed. Need to be height.

  However, if a relatively brittle (low mechanical strength) resist and a relatively hard (high mechanical strength) metal layer are polished at the same time, the resist breaks and the metal layer cannot be polished smoothly. The polishing rate of the metal layer in the region where the pattern density of the resist is high is increased as compared with the polishing rate of the metal layer in the region where the pattern density of the resist is low. As a result, the metal layer cannot be polished smoothly. As a result, the metal layer is not flattened, and the trench depth in the substrate surface may not be uniform.

  Therefore, the present invention has been made in view of such circumstances, and an object thereof is to provide a method for manufacturing a thin film capacitor capable of improving the uniformity of the capacitance while maintaining a high capacitance. .

  In order to solve the above problems, a method of manufacturing a thin film capacitor according to the present invention includes a first electrode having a recess, a dielectric layer provided on the first electrode, and a first electrode provided on the dielectric layer. A method of manufacturing a thin film capacitor having two electrodes, wherein (1) a base metal layer made of a first metal constituting a part of the first electrode is formed at least on a portion where a recess is formed on a substrate. A first step; (2) a second step of forming a coupon metal layer made of a second metal different from the first metal at a portion where a recess is formed on the substrate; and (3) a base metal layer and a coupon metal layer. A third step of plating an electrode metal layer made of the first metal constituting the remainder of the first electrode and filling the space between the coupon metal layers with the electrode metal layer; and (4) the coupon metal layer and the electrode metal layer. Polish the surface and remove the coupon metal layer A fourth step of exposing from the pole metal layer; (5) a fifth step of removing the coupon metal layer from the coupon metal layer and the electrode metal layer to form a recess and exposing a part of the base metal layer; (6) A sixth step of forming a dielectric layer on the electrode metal layer and the base metal layer, and (7) a seventh step of forming a second electrode on the dielectric layer.

  In the present invention, the first metal constituting the base metal layer and the first metal constituting the electrode metal layer are referred to as the same “first metal” for convenience, but the former first metal is the electrode metal layer. As long as it functions as a seed (layer) and a first electrode in the plating process at the time of formation, the type and composition of the latter first metal are not necessarily the same.

  In such a manufacturing method, first, a coupon metal layer made of a second metal different from the first metal of the base metal layer is formed on the base on which the base metal layer made of the first metal is formed in the first step. The The coupon metal layer is formed at a portion where the concave portion is formed, so to speak, it constitutes a reverse pattern of the concave portion. Next, an electrode metal layer made of a first metal is formed thereon, and the electrode metal layer is embedded between the coupon metal layers. Thereby, a composite of two different kinds of metals is formed. The surface of the composite is then polished and the coupon metal layer is exposed from the electrode metal layer.

  At this time, since the entire surface of the substrate is covered with the above-mentioned two kinds of metal composites, the mechanical strength of the entire object to be polished is sufficiently high and substantially uniform, whereby the object to be polished is lost due to polishing. In addition, the polishing rate in the plane of the substrate is uniform throughout. As a result, a smooth surface is formed in which the heights of the coupon metal layer and the electrode metal layer are the same in the substrate surface. Therefore, as will be described later, the depth of the recess formed by removing the coupon metal layer is made uniform, and the capacitance in the substrate surface of the finally obtained capacitor becomes uniform.

  Subsequently, only the coupon metal layer which is the reverse pattern of a recessed part is removed among a coupon metal layer and an electrode metal layer, and a recessed part is formed. Moreover, a part (part in a recessed part) of the base metal layer currently formed under the coupon metal layer is exposed to the bottom wall of a recessed part. At this time, the 1st electrode comprised from a base metal layer and an electrode metal layer is formed. Thereafter, a dielectric layer and a second electrode are sequentially laminated on the substrate, whereby a thin film capacitor having an electrode area increased by a recess is obtained.

Specifically, in the second step, a resist is applied on the base metal layer, a resist is removed from a portion of the resist where a recess is formed, an opening is formed, and a coupon metal layer is formed in the opening. Plating is preferred. Usually, the resist opening is formed through patterning exposure and development processes by photolithography, and the patterning accuracy is extremely high. Therefore, a coupon metal layer filled in the opening pattern, and thus an electrode formed between the coupon metal layers. The shape accuracy of the metal layer is increased and uniformized in the substrate surface. Therefore, the capacity uniformity of the thin film capacitor in the substrate surface is further improved, and the reproducibility between the substrates is also improved.

  In addition, when using either a negative type or a positive type as a resist, the opening width of the resist tends to be narrower at the bottom than the opening end, and the coupon metal layer filled in such an opening is Inverted taper shape. In this case, since the recess defined by the electrode metal layer filled between the coupon metal layers has a forward (positive) taper shape, the inner wall and the bottom wall of the recess are formed when the dielectric layer is formed thereon. The coverage (coverability) of the film becomes good, and the inside of the recess is reliably covered with the dielectric layer. Therefore, the occurrence of a short circuit or leakage current between the first electrode and the second electrode due to the lack of the dielectric layer is prevented. In addition, since the dielectric layer having a very thin and uniform thickness is formed, the capacitance of the thin film capacitor is further increased, and further thinning is achieved.

  Further, an eighth step of chamfering the open end portion of the electrode metal layer defining the concave portion after performing the fifth step of forming the concave portion and before performing the sixth step of forming the dielectric layer. Is preferably performed. In this way, the coverage of the dielectric layer at the opening end of the electrode metal layer is improved. As a result, in the electrode metal layer, the defect of the dielectric layer at the opening end where the capacitor structure is bent and the short circuit is relatively likely to occur is further prevented, and the occurrence of the short circuit and the leakage current is further suppressed. Furthermore, since an extremely thin and uniform dielectric layer is formed even at such a bent portion, the capacitance of the thin film capacitor is further increased, and further thinning is realized.

  In this case, more specifically, it is preferable to chamfer the open end portion of the electrode metal layer that defines the recess by milling or etching, more preferably milling. In ion milling and etching, the milling rate and etch rate at the corners tend to be significantly higher than the side milling rate and side etch rate of the inner wall of the recess and the milling rate and etch rate of the recess bottom wall. The chamfering of the opening end is easily performed without scraping off the electrode metal layer constituting the inner wall and the base metal layer constituting the bottom wall.

  Furthermore, it is more preferable to use a metal that is soluble in one of acid and alkali as the first metal, and a metal that is insoluble in the solvent of the first metal as the second metal. If it carries out like this, there exists an advantage which can carry out wet removal of a coupon metal layer easily among the coupon metal layer which consists of a 1st metal, and the electrode metal layer which consists of a 2nd metal by using the solvent of a 1st metal.

  More specifically, a metal (Ni, Ni alloy, Ni composite metal) mainly containing nickel (Ni) soluble in alkali is used as the first metal, and copper (Cu) insoluble in alkali is mainly used as the second metal. It is useful to use a metal (Cu, Cu alloy, Cu composite metal).

  According to the method for manufacturing a thin film capacitor of the present invention, the recess is formed by forming the electrode metal layer after forming the reverse pattern of the recess with the coupon metal layer made of the first metal, and removing the coupon metal layer to form the recess. Therefore, a thin film capacitor with improved capacitance uniformity can be manufactured while maintaining a high capacitance.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios. The following embodiments are examples for explaining the present invention, and the present invention is not limited only to the embodiments.

  1 and 2 are a perspective view and a plan view, respectively, showing a schematic configuration of a preferred embodiment of a thin film capacitor manufactured by using the method of manufacturing a thin film capacitor according to the present invention, and FIG. 3 is a cross-sectional view taken along line III-III in FIG.

  The thin film capacitor 1 includes an electrode metal layer 14 having a trench 14a (concave portion) on a base metal layer 11 formed on the entire surface of a substrate (base body) 10, and a dielectric film 16 (covering the electrode metal layer 14). Dielectric layer) and upper electrode 17 (second electrode) are sequentially laminated. Thus, the lower electrode 15 (first electrode) is constituted by the base metal layer 11 and the electrode metal layer 14. In addition, as an upper layer of the upper electrode 17, an insulating protective film 18 (passivation film) in which two openings 18a from which the upper electrode 17 and the lower electrode 15 are exposed is formed. Further, a pad electrode 19 is connected to each of the two openings 18 a of the protective film 18.

  In the drawing, one unit of the thin film capacitor 1 is shown, and a plurality of such thin film capacitors 1 may be formed on the substrate 10.

Here, the capacitance of the thin film capacitor 1 is expressed by the following formula (1);
C = ε × S / d (1),
It is represented by In the equation, C represents the capacitance, ε represents the dielectric constant of the dielectric film 16, S represents the electrode surface area, and d represents the thickness of the dielectric film 16. The dielectric constant ε is expressed by the following formula (2);
ε = ε _r ε _o (2),
Ε _r represents the relative dielectric constant of the dielectric film 16, and ε _o represents the relative dielectric constant in vacuum.

  Therefore, in order to increase the capacitance C per unit volume of the thin film capacitor 1, when the dielectric constant ε of the dielectric film 16 is constant, the electrode surface area S of the thin film capacitor 1 is increased and / or the dielectric It is necessary to reduce the thickness d of the body film 16. In addition, in order to suppress the variation in the capacitance within the surface of the substrate 10 of the single or plural thin film capacitors 1 formed on one substrate 10, the electrode surface area of each thin film capacitor 1 is made uniform, and the dielectric film 16 It is important to make the thickness d uniform. In particular, in the trench type thin film capacitor 1, in order to ensure the uniformity of the electrode surface area in the surface of the substrate 10, the area of each trench 14a (peripheral length of the trench 14a × It is very important to make the depth + bottom area uniform.

  An example of a method for manufacturing the thin film capacitor 1 configured as described above will be described below. 4 to 20 are cross-sectional views (process flow diagrams) showing a state in which the thin film capacitor 1 is manufactured.

First, as shown in FIG. 4, a substrate 10 on which the thin film capacitor 1 is provided is prepared. The substrate 10 is not particularly limited, and examples thereof include a silicon substrate, a ceramic substrate such as alumina, a glass ceramic substrate, a glass substrate, a single crystal substrate such as sapphire, MgO, and SrTiO ₃ , and a metal substrate such as Fe—Ni alloy. It is preferable to use a material that is chemically and thermally stable, generates less stress, and easily maintains the smoothness of the surface. In addition, when a conductive substrate such as a metal substrate or a silicon substrate is used as the substrate 10, it is preferable to form an insulating film such as an oxide film on the surface of the substrate 10 in order to ensure insulation.

  Next, as shown in FIG. 5, a base metal layer 11 is formed on the substrate 10 (first step). The material (first metal) of the base metal layer 11 is not particularly limited as long as it is a metal layer, but if the same material (first metal) as that of the electrode metal layer 14 constituting the lower electrode 15 is used, a coupon metal described later is used. When the layer 13 is removed, it is preferable because peeling and missing of the base metal layer 11 are easily prevented. Examples of such a metal material include metals mainly containing Au, Pt, Ag, Sn, Cr, Co, Ni, Cu, etc., alloys thereof, or composite metals containing them. Among these, Ni is mainly used. It is particularly preferable to use a material that contains the material. If a material containing mainly Ni is used, the film stress to be formed can be made almost zero, so that the warpage of the base metal layer 11, the electrode metal layer 14, and the lower electrode 15 and the substrate 10 can be effectively prevented. . The base metal layer 11 made of such a metal material can be formed by, for example, a PVD method such as a sputtering method or a CVD method.

  Next, as shown in FIG. 6, a resist layer 12 (resist) is formed on the base metal layer 11. As the resist layer 12, a negative resist or a positive resist may be used. When a negative resist is used, patterning accuracy can be further improved by using a chemically amplified type resist. Therefore, it is preferable.

  Then, as shown in FIG. 7, the resist layer 12 is exposed and developed using the mask pattern of the trench 14a to form an opening 12a in a portion where the trench 14a is to be formed, and a base metal is formed at the bottom of the opening 12a. Layer 11 is exposed. When a positive resist is used, the region where the opening 12a is to be formed is exposed, and the exposed portion of the resist is dissolved in the developer. When a negative resist is used, a region other than the opening is exposed, and the unexposed portion of the resist is dissolved in the developer. In the case of using either a positive type or a negative type resist, the upper side of the opening 12a has a longer time to be immersed in the developer than the bottom side. Therefore, the width on the bottom side of the opening 12a is equal to or less than the width on the opening end (upper) side.

  Next, as shown in FIG. 8, a coupon metal layer 13 having a reverse pattern (transfer pattern) of the trench 14a is formed in the opening 12a of the resist layer 12 by plating. The “coupon” is a term used formally to clarify the distinction from the electrode metal layer 14, and as described later, it is removed after the electrode metal layer 14 is formed. Since the “no ticket” mode is recalled, it is used for convenience in the present invention.

  Here, as plating, electroplating or electroless plating (chemical plating) may be used. For example, the coupon metal layer 13 is formed by electroplating using the base metal layer 11 as a base. The material (second metal) of the coupon metal layer 13 is a metal mainly containing Au, Pt, Ag, Sn, Cr, Co, Ni, Cu, etc., an alloy thereof, or a composite metal containing these, A material different from the material of the metal layer 11 and the electrode metal layer 14 is used. For example, when the base metal layer 11 and the electrode metal layer 14 mainly containing Ni are used as described above, the coupon metal layer 13 is mainly used. It is preferable to use Cu.

  Thereafter, as shown in FIG. 9, the resist layer 12 is removed. At this time, when the opening 12a has a forward (forward) taper shape, the coupon metal layer 13 has a reverse taper shape. As described above, the procedure shown in FIGS. 6 to 9 corresponds to the second step.

  Next, as shown in FIG. 10, an electrode metal layer 14 that fills the space between the coupon metal layers 13 is formed by plating (third step). Thereby, a composite of two different kinds of metals is formed. As plating, similarly to the coupon metal layer 13, electroplating or electroless plating (chemical plating) may be used. For example, the electrode metal layer 14 is formed by electroplating with the base metal layer 11 as a base. Form. Thereby, the coupon metal layer 13 is covered with the electrode metal layer 14. The electrode metal layer 14 is made of a material different from the coupon metal layer 13 among metals mainly containing Au, Pt, Ag, Sn, Cr, Co, Ni, Cu, alloys thereof, or composite metals containing these metals. For example, when the one containing mainly Cu is used as the coupon metal layer 13 as described above, it is preferable to use one containing mainly Ni as the electrode metal layer 14.

  Then, as shown in FIG. 11, the surface of the composite comprising the coupon metal layer 13 and the electrode metal layer 14 is polished and flattened by CMP (Circular Movement Polishing or Chemical Mechanical Polishing), and the coupon metal layer 13 And the height of the electrode metal layer 14 is made uniform. At this time, first, after the electrode metal layer 14 is polished to expose the coupon metal layer 13, both the coupon metal layer 13 and the electrode metal layer 14 are polished (fourth step). Thereby, the height of the coupon metal layer 13 becomes lower than the initial height shown in FIG.

  Next, as shown in FIG. 12, the coupon metal layer 13 is removed, thereby forming a trench 14 a that is a spatial region corresponding to the shape of the coupon metal layer 13, and a part of the base metal layer 11 is formed at the bottom thereof. Expose (fifth step). When the coupon metal layer 13 is formed in a reverse taper shape, the space shape of the trench 14a becomes a forward (positive) taper shape.

  As a method of removing the coupon metal layer 13, as described above, when the coupon metal layer 13 is mainly made of a metal containing Cu, the substrate 10 in the state shown in FIG. It is preferable to immerse in (alkali), and although the metal material mainly containing Ni which is a metal material of the base metal layer 11 and the electrode metal layer 14 is slightly dissolved, cerium ammonium sulfate, cerium ammonium nitrate, etc. It can also be used. Thereby, the coupon metal layer 13 is selectively removed.

  After that, as shown in FIG. 13, the ridgeline of the opening end portion 14b (the portion surrounded by a circle in the drawing) of the electrode metal layer 14 (the portion surrounded by a circle in the drawing) is chamfered to further improve the coverage of the dielectric film. (In other words, a rounding process is performed to form a curved surface by rounding the electrode metal layer 14 (eighth step)). The chamfering process of the trench 14a of the electrode metal layer 14 is not particularly limited as long as it is a method capable of removing a part of the opening end 14b of the electrode metal layer 14, and an entire surface ion milling process or a wet or dry etching process is used. be able to.

  In ion milling and etching, the milling rate and etch rate at the corners such as the open end 14b are significantly higher than the side milling rate and side etch rate of the inner wall of the trench 14a and the milling rate and etch rate of the bottom wall. Since it tends to be large, the opening end 14b is selectively chamfered without scraping off the electrode metal layer 14 constituting the inner wall of the trench 14a or the base metal layer 11 constituting the bottom wall. In particular, according to milling, the difference in the milling rate between the corner portion such as the opening end portion 14b and the flat end portion such as the inner wall and the bottom wall of the trench 14a is larger than the difference in etching etch rate (see FIG. That is, the selective removal property is high), which is more preferable. Thereby, the formation of the lower electrode 15 composed of the base metal layer 11 and the electrode metal layer 14 is completed.

Next, as shown in FIG. 14, a dielectric film 16 is formed on the entire top surface of the substrate 10 in the state shown in FIG. 13 (sixth step). As a result, the inner wall of the trench 14 a and the electrode metal layer 14 are covered with the dielectric film 16. The material of the dielectric film 16 is not particularly limited. For example, a dielectric material such as Al ₂ O ₃ , PZT, or BaTiO ₃ can be used. From the viewpoint of increasing the capacitance C, the relative dielectric constant ε It is preferable to use a ferroelectric material such as PZT or BaTiO ₃ having a large _r . In the case of using such a ferroelectric material, after the dielectric film 16 is formed, heat treatment for exciting the dielectric polarization is performed as necessary. As a method for forming the dielectric film 16, a CVD method, a PVD method, or the like can be used. In particular, the dielectric film 16 is excellent in step coverage, and the thickness d of the dielectric film 16 is made thin and uniform. From the viewpoint of easily increasing and uniforming the capacitance C, it is preferable to use the CVD method.

  Further, as shown in FIG. 15, a resist pattern having an opening (through hole, via hole) is formed in the connection region between the lower electrode 15 and the pad electrode 19, and the dielectric film 16 in the opening is removed by RIE or the like. To do.

  Next, as shown in FIG. 16, an electrode film 17a for forming the upper electrode 17 is formed on the entire upper surface of the substrate 10 in the state shown in FIG. The material of the upper electrode 17 is not particularly limited, and examples thereof include Cu, Ni, and Al. For example, a PVD method such as a sputtering method can be used to form the electrode film 17a.

  Thereafter, as shown in FIG. 17, a resist pattern is formed on the electrode film 17a by a photolithography process, and patterning is performed by etching a part of the electrode film 17a using the resist pattern, thereby forming the upper electrode 17 (see FIG. 17). (7th process). At this time, the upper electrode 17 is patterned to the inside of the planar outer periphery of the dielectric film 16 so as not to contact the lower electrode 15 at the end thereof.

Then, as shown in FIG. 18, a protective film 18 is formed on the entire upper surface of the substrate 10 in the state shown in FIG. The protective film 18 is not particularly limited as long as it is an insulating material. For example, inorganic materials such as SiO ₂ and Al ₂ O ₃ , and organic materials such as polyimide and epoxy can be used. Further, the thickness of the protective film 18 is not particularly limited and is, for example, 2 μm or more.

  Next, as shown in FIG. 19, the protective film 18 in the region where the pad electrode 19 is to be formed is removed by patterning using photolithography, and two openings 18 a are formed in the protective film 18. As a result, the electrode metal layer 14 constituting a part of the lower electrode 15 is exposed on one end side (right side in the drawing) of the protective film 18, and the upper electrode 17 is placed on the other end side (left side in the drawing). Expose.

  Then, as shown in FIG. 20, an electrode film is formed on the entire upper surface of the substrate 10 in the state shown in FIG. 19, and the electrode film is patterned using photolithography, whereby the openings 18a and 18a are padded. Electrodes 19 are formed. Alternatively, a resist is formed in a region other than the openings 18a and 18a, and after the pad electrode 19 is formed in the opening 18a by plating, the resist is removed. The material of the pad electrode 19 is not particularly limited, and for example, Au can be used.

  According to such a method of manufacturing a thin film capacitor according to the present embodiment, after the pattern of the coupon metal layer 13 is once formed in the portion where the trench 14a is formed, the region between the coupon metal layers 13 is included. The electrode metal layer 14 is formed so as to cover the entire upper surface of the substrate 10, and the composite composed of the coupon metal layer 13 and the electrode metal layer 14 is polished by CMP, so that the surface to be polished is formed of only the metal layer. As a result, the mechanical strength (hardness) of the surface to be polished is sufficiently increased and substantially uniform within the surface of the substrate 10. Therefore, it is possible to prevent the object to be polished from being lost during the CMP, and to make the polishing rate within the surface of the substrate 10 uniform throughout. This makes it possible to form a smooth surface in which the coupon metal layer 13 and the electrode metal layer 14 have the same height in the surface of the substrate 10, even if the aspect ratio of the trench 14 a in the surface of the substrate 10 is high. Since the depth can be surely made uniform, variations in capacitance among a plurality of thin film capacitors in the substrate surface can be sufficiently suppressed while increasing the capacitance of the capacitor.

  Further, since patterning by photolithography using a resist is used to form the coupon metal layer 13 that determines the shape of the trench 14a, the patterning accuracy of the trench 14a is sufficiently increased, and the coupon metal filled in the pattern is used. The shape accuracy of the electrode metal layer 14 formed between the layer 13 and the coupon metal layer 13 can be remarkably increased and can be made uniform within the surface of the substrate 10. Therefore, the capacity uniformity of the thin film capacitor within the surface of the substrate 10 can be further improved, and the reproducibility between different substrates 10 can also be improved.

Furthermore, when providing the coupon metal layer 13 which is the reverse pattern of the trench 14a, the sidewall of the opening 12a of the resist layer 12 tends to be forward (positive) tapered. In this case, the coupon metal layer 13 As a result of the reverse taper shape, the spatial shape of the trench 14a becomes a forward (positive) taper shape, so that the coverage (coverability) in the trench 14a by the dielectric film 16 is improved, and the trench 14a is surely covered by the dielectric film 16. Can be coated. As a result, the short-circuit between the lower electrode 15 and the upper electrode 17 and the occurrence of a leakage current due to the lack of the dielectric film 16 are prevented, so that the breakdown voltage between the lower electrode 15 and the upper electrode 17 (dielectric breakdown limit value: V _BD ) can be sufficiently increased, and the device characteristics of the thin film capacitor 1 and the reliability of the product can be improved. Furthermore, since the coverage in the trench 14a by the dielectric film 16 can be increased, the dielectric film 16 having a very thin and uniform film thickness can be formed, thereby further increasing the capacitance of the thin film capacitor 1. In addition, further thinning can be realized.

  Furthermore, since the trench 14a has a positive taper shape, the coverage of the electrode film 17a can be improved. However, since the thickness of the upper electrode 17 and variations thereof hardly affect the capacitance of the thin film capacitor 1, there is no problem even if the film thickness of the electrode film 17a is reduced on the side surface of the trench 14a.

In addition, by adding a chamfering process to the opening end portion 14b of the electrode metal layer 14 before forming the dielectric film 16, the capacitor structure is bent and the opening end portion 14b that is relatively short-circuited is likely to occur. The coverage, that is, the step coverage of the trench 14a by the dielectric film 16 can be improved. As a result, the loss of the dielectric film 16 at the opening end 14b of the electrode metal layer 14 can be prevented, the occurrence of short circuits and leakage currents can be further suppressed, and the yield of the thin film capacitor 1 can be improved. Furthermore, the V _BD between the lower electrode 15 and the upper electrode 17 can be further increased, and the device characteristics and product reliability of the thin film capacitor 1 can be further improved. In addition, since the step coverage by the dielectric film 16 can be improved, the dielectric film 16 having a very thin and uniform thickness can be formed, and the capacitance of the thin film capacitor 1 can be further increased. Further thinning can be achieved.

  In addition, as above-mentioned, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary. For example, the trench 14a may have a rectangular or circular hole shape or a groove structure extending straight or curved in a predetermined direction, and a pattern in the substrate 10 can be appropriately set.

  As described above, according to the method of manufacturing a thin film capacitor of the present invention, a thin film capacitor with improved capacitance uniformity can be manufactured while maintaining a high capacitance. It can be widely and effectively used for manufacturing applications of devices, apparatuses, systems, various devices, etc. that contain components, especially those that require miniaturization and high performance.

It is a perspective view which shows schematic structure of one suitable embodiment of the thin film capacitor manufactured using the manufacturing method of the thin film capacitor by this invention. It is a top view which shows schematic structure of suitable one Embodiment of the thin film capacitor manufactured using the manufacturing method of the thin film capacitor by this invention. It is sectional drawing which follows the III-III line in FIG. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor. It is sectional drawing which shows the state which manufactures the thin film capacitor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Thin film capacitor, 10 ... Board | substrate (base | substrate), 11 ... Base metal layer, 12 ... Resist layer (resist), 12a ... Opening part, 13 ... Coupon metal layer, 14 ... Electrode metal layer, 14a ... Trench (recessed part), 14b ... Opening edge, 15 ... Lower electrode (first electrode), 16 ... Dielectric film (dielectric layer), 17 ... Upper electrode (second electrode), 17a ... Electrode film, 18 ... Protective film, 18a ... Opening Part, 19 ... pad electrode.

Claims (6)

A method of manufacturing a thin film capacitor comprising a first electrode having a recess provided on a substrate, a dielectric layer provided on the first electrode, and a second electrode provided on the dielectric layer. There,
A first step of forming a base metal layer made of a first metal constituting a part of the first electrode in at least a portion where the recess is formed on the substrate;
A second step of forming a coupon metal layer made of a second metal different from the first metal at a portion where the recess is formed on the substrate;
A third step of plating an electrode metal layer made of a first metal constituting the remaining portion of the first electrode on the base metal layer and the coupon metal layer, and filling the space between the coupon metal layers with the electrode metal layer; ,
Polishing a surface of the coupon metal layer and the electrode metal layer to expose the coupon metal layer from the electrode metal layer;
A fifth step of removing the coupon metal layer from the coupon metal layer and the electrode metal layer to form the recess and exposing a part of the base metal layer;
A sixth step of forming the dielectric layer on the electrode metal layer and the base metal layer;
A seventh step of forming the second electrode on the dielectric layer;
The manufacturing method of the thin film capacitor which has this. In the second step,
Apply a resist on the base metal layer,
The resist is removed from the resist where the recess is to be formed to form an opening,
Plating the coupon metal layer into the opening;
A method for manufacturing the thin film capacitor according to claim 1. Comprising an eighth step of chamfering the open end of the electrode metal layer defining the recess,
A method for manufacturing the thin film capacitor according to claim 1. In the eighth step, the open end of the electrode metal layer defining the recess is chamfered by milling or etching.
A method of manufacturing a thin film capacitor according to claim 3. Using a metal soluble in one of acid and alkali as the first metal, and using a metal insoluble in one of the acid and alkali as the second metal,
A method for manufacturing the thin film capacitor according to claim 1. A metal mainly containing nickel is used as the first metal, and a metal mainly containing copper is used as the second metal.
A method for manufacturing a thin film capacitor according to claim 5.

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