Method and structure of manufacturing a high-q inductor with an air trench
First Claim
1. A structure of an inductor with an air trench, comprising:
- a substrate;
a plurality of spiral metal lines formed over the substrate;
a plurality of dielectric layers, each of which is formed between two adjacent spiral metal lines;
a plurality of via plugs formed in the dielectric layers to connect the spiral metal lines to each other;
a spiral air trench formed along the spacing of the spiral metal lines in the dielectric layers;
a first connective line connecting the inner end of a lower spiral metal line; and
a second connective line connecting the outer end of an upper spiral metal line.
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Abstract
The structure of a high-Q inductor applied in a monolithic circuit according to the invention comprises a plurality of spiral metal lines and a plurality of dielectric layers, each dielectric layer formed between two adjacent spiral metal lines. Furthermore, via plugs are formed in each dielectric layer to electrically connect two adjacent spiral metal lines. A spiral air trench is formed along the spacing of the spiral metal lines in the dielectric layers. Therefore, the 3D-structure of the inductor of the invention can greatly reduce the series resistance thereof without widening the spiral metal lines. In addition, the spiral air trench, filled with air which has a lower dielectric constant, can efficiently reduce the parasitic capacitance between the spacing of the spiral metal lines. As a result, the inductor of the invention has a higher quality factor at a proper RF operating frequency region.
73 Citations
17 Claims
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1. A structure of an inductor with an air trench, comprising:
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a substrate;
a plurality of spiral metal lines formed over the substrate;
a plurality of dielectric layers, each of which is formed between two adjacent spiral metal lines;
a plurality of via plugs formed in the dielectric layers to connect the spiral metal lines to each other;
a spiral air trench formed along the spacing of the spiral metal lines in the dielectric layers;
a first connective line connecting the inner end of a lower spiral metal line; and
a second connective line connecting the outer end of an upper spiral metal line. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of manufacturing an inductor with an air trench, which is applied in monolithic circuit processing, the method comprising the steps of:
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(a) providing a substrate having at least one insulator formed thereon;
(b) forming a lower metal line, serving as a first connective line, on the insulator;
(c) forming a lower dielectric layer, which has at least one via hole, on the lower metal line, wherein the via hole is filled with a first via plug for connecting the lower metal line;
(d) forming a spiral metal line, one end of which is electrically connected to the first via plug, on the lower dielectric layer;
(e) forming a dielectric layer, which has at least one via hole, on the spiral metal line, wherein the via hole is filled with a second via plug for connecting the spiral metal line;
(f) repeating steps (a)-(e) to form a spiral inductor structure;
(g) forming an upper spiral metal line having a second connective line, which is aligned with and electrically connected to the spiral inductor structure, over the substrate;
(h) forming an upper dielectric layer on the upper spiral metal line and over the substrate;
(i) forming a mask on the upper dielectric layer with only the part just above the spacing of the spiral inductor exposed; and
(j) forming a spiral air trench in the upper dielectric layer and the dielectric layer by etching until the lower dielectric layer is exposed. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification