Contact structures in RC-network components
RC-network components that include a substrate and capacitor having a thin-film top electrode portion at a surface on one side of the substrate. The low ohmic semiconductor substrate is doped to contribute 5% or less to the resistance of the RC-network component. The resistance provided in series with the capacitor is controlled by providing a contact plate, spaced from the thin-film top electrode portion by an insulating layer, and a set of one or more bridging contacts passing through openings in the insulating layer. The bridging contacts electrically interconnect the thin-film top electrode portion and the contact plate. Different resistance values can be set by appropriate selection of the number of bridging contacts. The openings are elongated thereby reducing temperature concentration at their periphery. Correspondingly, the bridging contacts have an elongated cross-sectional shape.
1. An integrated RC-network component comprising:
a substrate;
a capacitor having a thin-film top electrode portion at a surface on a first side of the substrate;
an insulating layer on the thin-film top electrode portion of the capacitor;
a contact plate on the insulating layer, and
one or more bridging contacts in openings traversing the insulating layer, the bridging contacts electrically connecting the thin-film top electrode portion of the capacitor to the contact plate,
wherein the RC-network component has first and second contacts, the first contact comprising said contact plate, and a series RC circuit is present between the first and second contacts,
wherein the substrate is a low ohmic doped semiconductor substrate that makes a contribution of no more than 5% to a resistance of the RC-network component,
wherein, in a direction of a thickness of the thin-film top electrode portion of the capacitor, a length of the bridging contacts is sufficiently greater than the thickness of the thin-film top electrode portion that an equivalent series resistance of the capacitor is proportional to a sheet resistance of the thin-film top electrode portion divided by a number of the bridging contacts, and
wherein the openings have an elongated peripheral shape having an aspect ratio greater than 1:1.
2. The RC-network component according to claim 1 , wherein the aspect ratio is greater than 2:1.
3. The RC-network component according to claim 1 , wherein the openings have a rectangular peripheral shape.
4. The RC-network component according to claim 1 , wherein said openings in the insulating layer comprise one, or more than one, elongated opening spanning the thin-film top electrode portion of the capacitor.
5. The RC-network component according to claim 1 , wherein the openings have an elliptical peripheral shape.
6. The RC-network component according to claim 1 , wherein the bridging contacts are made of a material having conductivity greater than that of a material forming the thin-film top electrode portion.
7. The RC-network component according to claim 6 , wherein the bridging contacts and the contact plate are integrally formed of a same material.
8. The RC-network component according to claim 1 , wherein the thin-film top electrode portion of the capacitor is made of polysilicon.
9. The RC-network component according to claim 1 , wherein the contact plate and the thin-film top electrode portion of the capacitor have a same peripheral shape.
10. The RC-network component according to claim 1 , wherein the contact plate and the thin-film top electrode portion of the capacitor have a same size.
11. The RC-network component according to claim 1 , wherein the capacitor is a 3D capacitor, and a bottom electrode of the 3D capacitor comprises the low ohmic semiconductor substrate.
12. The RC-network component according to claim 1 , wherein an only part of the thin-film top electrode portion to be located at said surface on the first side of the substrate is a single planar sheet comprising said thin-film top electrode portion.
13. A monolithic RC-network component according to claim 1 .
14. A method of fabricating an RC-network component, the method comprising:
forming a capacitor having a thin-film top electrode portion at a surface on a first side of a substrate;
forming an insulating layer on the thin-film electrode portion of the capacitor;
forming one or more bridging contacts traversing openings in the insulating layer; and
forming a plate-shaped contact on the insulating layer;
wherein the bridging contacts electrically connect the thin-film top electrode portion of the capacitor to the plate-shaped contact,
wherein the RC-network component has first and second contacts, the first contact comprising a contact plate, and a series RC circuit is formed between the first and second contacts,
wherein the substrate is a low ohmic semiconductor substrate doped to make a contribution of no more than 5% to a resistance of the RC-network component,
wherein, in a direction of a thickness of the thin-film top electrode portion of the capacitor, a length of the bridging contacts is sufficiently greater than the thickness of the thin-film top electrode portion that an equivalent series resistance of the capacitor is proportional to a sheet resistance of the thin-film top electrode portion divided by a number of the bridging contacts, and
wherein the openings in the insulating layer have an elongated peripheral shape having an aspect ratio equal to or greater than 1:1.