To provide a thin film capacitor in which warpage is less likely to occur. A thin film capacitor includes: a metal foil having roughened upper and lower surfaces; a dielectric film covering the upper surface of the metal foil and having an opening through which the metal foil is partly exposed; a dielectric film covering the lower surface of the metal foil and made of a dielectric material having a thermal expansion coefficient smaller than that of the metal foil; a first electrode layer contacting the metal foil through the opening; and a second electrode layer contacting the first dielectric film without contacting the metal foil. The lower surface of the metal foil is thus covered with the dielectric film having a small thermal expansion coefficient, thereby making it possible to prevent the occurrence of warpage.

To provide a thin film capacitor having high adhesion performance with respect to a circuit substrate. A thin film capacitor includes: a metal foil having a roughened upper surface; a dielectric film covering the upper surface of the metal foil and having an opening through which the metal foil is partly exposed; a first electrode layer contacting the metal foil through the opening; and a second electrode layer contacting the dielectric film without contacting the metal foil. The first and second electrode layers are formed in an area surrounded by an outer peripheral area of the upper surface of the metal foil so as not to cover the outer peripheral area. The outer peripheral area of the roughened upper surface of the metal foil is thus exposed, so that adhesion performance with respect to a circuit substrate can be enhanced.

To provide a thin film capacitor having high adhesion performance with respect to a circuit substrate. A thin film capacitor includes: a metal foil having a roughened upper surface; a dielectric film covering the upper surface of the metal foil and having an opening through which the metal foil is partly exposed; a first electrode layer contacting the metal foil through the opening; and a second electrode layer contacting the dielectric film without contacting the metal foil. The first and second electrode layers are formed in an area surrounded by an outer peripheral area of the upper surface of the metal foil so as not to cover the outer peripheral area. The outer peripheral area of the roughened upper surface of the metal foil is thus exposed, so that adhesion performance with respect to a circuit substrate can be enhanced.

To provide a thin film capacitor in which a pair of terminal electrodes can be disposed on the same plane. A thin film capacitor includes a metal foil having a roughened upper surface, a dielectric film covering the upper surface of the metal foil and having an opening for partly exposing the metal foil therethrough, a first electrode layer contacting the metal foil through the opening, and a second electrode layer contacting the dielectric film without contacting the metal foil. With this configuration, both the first and second electrode layers can be disposed on the upper surface of the metal foil. In addition, since the metal foil is surface-roughened, a larger capacitance can be obtained.

To provide a thin film capacitor in which a pair of terminal electrodes can be disposed on the same plane. A thin film capacitor includes a metal foil having a roughened upper surface, a dielectric film covering the upper surface of the metal foil and having an opening for partly exposing the metal foil therethrough, a first electrode layer contacting the metal foil through the opening, and a second electrode layer contacting the dielectric film without contacting the metal foil. With this configuration, both the first and second electrode layers can be disposed on the upper surface of the metal foil. In addition, since the metal foil is surface-roughened, a larger capacitance can be obtained.

To provide a thin film capacitor having high flexibility. A thin film capacitor includes: a metal foil having a roughened upper surface; a dielectric film covering the upper surface of the metal foil and having an opening through which the metal foil is partly exposed; a first electrode layer contacting the metal foil through the opening; and a second electrode layer contacting the dielectric film without contacting the metal foil. The particle diameter of crystal at a non-roughened center part of the metal foil is less than 15 μm in the planar direction and less than 5 μm in the thickness direction. This can not only enhance the flexibility of the metal foil to reduce a short-circuit failure in a state where the thin film capacitor is incorporated in a multilayer substrate but also enhance positional accuracy.

To provide a thin film capacitor having high flexibility. A thin film capacitor includes: a metal foil having a roughened upper surface; a dielectric film covering the upper surface of the metal foil and having an opening through which the metal foil is partly exposed; a first electrode layer contacting the metal foil through the opening; and a second electrode layer contacting the dielectric film without contacting the metal foil. The particle diameter of crystal at a non-roughened center part of the metal foil is less than 15 μm in the planar direction and less than 5 μm in the thickness direction. This can not only enhance the flexibility of the metal foil to reduce a short-circuit failure in a state where the thin film capacitor is incorporated in a multilayer substrate but also enhance positional accuracy.

A unit trench capacitor in a substrate includes one or more trenches in the substrate, a dielectric layer, a first electrode and a second electrode. Walls of the one or more trenches are covered by the dielectric layer which separates the first electrode from the second electrode. Each trench follows a closed curve. The closed curve of each trench has one or more elongated parts in directions in which the substrate has a maximum elastic modulus, or the closed curve of each trench has a circular shape if the substrate has an isotropic elastic modulus.

A unit trench capacitor in a substrate includes one or more trenches in the substrate, a dielectric layer, a first electrode and a second electrode. Walls of the one or more trenches are covered by the dielectric layer which separates the first electrode from the second electrode. Each trench follows a closed curve. The closed curve of each trench has one or more elongated parts in directions in which the substrate has a maximum elastic modulus, or the closed curve of each trench has a circular shape if the substrate has an isotropic elastic modulus.

A trench capacitor includes a plurality of unit trench capacitors arranged in a 2D repetitive pattern in a substrate. The unit trench capacitors are separated by elongated trenches or elongated walls between the unit trench capacitors. The trench capacitor includes a plurality of stress compensation elements. Each unit trench capacitor has one or more closed trenches, with each trench further having a bottom electrode, a top electrode, and a dielectric between the bottom electrode and the top electrode. The unit trench capacitors are connected in parallel and the stress compensation elements are arranged between the unit trench capacitors such that they interrupt the elongated walls or trenches.