Thin film capacitor and circuit board incorporating the same

A circuit board in which a thin film capacitor is embedded,

• wherein the thin film capacitor comprises:
• a capacitive insulating film;
• a first metal film formed on one surface of the capacitive insulating film;
• and
• a second metal film formed on another surface of the capacitive insulating film and made of a metal material different from that of the first metal film,
• wherein the thin film capacitor has an opening penetrating the capacitive insulating film, first metal film, and second metal film,
• wherein the second metal film is thicker than the first metal film,
• wherein a first size of a part of the opening that penetrates the first metal film is larger than a second size of a part of the opening that penetrates the second metal film, and
• wherein the circuit board includes a via conductor that passes through the opening without contacting the first and second metal films
• wherein a third size of a part of the opening that penetrates the capacitive insulating film is smaller than the first size, and
• wherein the third size is smaller than a fourth size of a part of the opening that penetrates the second metal film at a boundary of the capacitive insulating film.

A thin film capacitor comprising:

• a first metal film having a first opening having a first size;
• a second metal film having a second opening having a second size, the second metal film being thicker than the first metal film;
• and
• a capacitive insulating film having a third opening having a third size,
• wherein the capacitive insulating film is disposed between the first metal film and the second metal film, and that the first, second, and third openings overlap one another,
• wherein the third size is smaller than the first size and larger than the second size,
• wherein the second opening includes a first section adjacent to the capacitive insulating film and a second section farther from the capacitive insulating film than the first section, and
• wherein a size of the second opening in the second section is the second size.

A thin film capacitor comprising:

• a first metal film having a first opening having a first size;
• a second metal film having a second opening having a second size, the second metal film being thicker than the first metal film;
• and
• a capacitive insulating film having a third opening having a third size,
• wherein the capacitive insulating film is disposed between the first metal film and the second metal film, and that the first, second, and third openings overlap one another,
• wherein the third size is smaller than the first size and larger than the second size,
• wherein an inner wall of the second opening is tapered such that the second opening is smaller as approaching the capacitive insulating film, and
• wherein an inner wall of the third opening is tapered such that the third opening is smaller as approaching the second metal film.