SEMICONDUCTOR SUBSTRATE FOR TRANSMITTING DIFFERENTIAL PAIR

Abstract

A semiconductor substrate for transmitting a differential pair is provided. The semiconductor substrate includes a substrate body and at least one via. The via has an opening on a surface layer of the substrate body and includes a first conductive element, a second conductive element and a ground element therein. The first conductive element, the second conductive element and the ground element are electrically isolated to one another. The ground element is electrically connected to a ground layer of the substrate body. The first conductive element and the second conductive element pass through the ground layer of the substrate body and are electrically isolated with the ground layer of the substrate body. The first conductive element is used for transmitting a positive differential signal and the second conductive element is used for transmitting a negative differential signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a diagram of a conventional semiconductor substrate for transmitting a differential pair.

FIG. 2 is a diagram of a semiconductor substrate for transmitting a differential pair according to a first embodiment of the present invention.

FIG. 3 is a diagram of a semiconductor substrate for transmitting a differential pair according to a second embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

FIG. 2 is a diagram of a semiconductor substrate for transmitting a differential pair according to a first embodiment of the present invention. The semiconductor substrate 2 includes a substrate body 21, at least one via 22, a first circuit 23 and a second circuit 24. The substrate body 21 has a surface layer 211, a ground layer 212 and a plurality of dielectric layers 213. The ground layer 212 can be fully or partially distributed between two dielectric layers 213.

The via 22 has an opening on the surface layer 211 of the substrate body 21. The via 22 can be a blind via or a through via. The via 22 has a first conductive element 221, a second conductive element 222 and a ground element 223 therein. The first conductive element 221, the second conductive element 222 and the ground element 223 are separate and electrically isolated to one another. The ground element 223 is electrically connected to the ground layer 212 of the substrate body 21. The first conductive element 221 and the second conductive element 222 pass through the ground layer 212 of the substrate body 21 and are electrically isolated with the ground layer 212 of the substrate body 21.

In the present embodiment, the method of forming the first conductive element 221, the second conductive element 222 and the ground element 223 includes, for example, the following steps. First, the via 22 is filled with a conductive material such as a metal. Then, a laser cutting operation is performed to cut the block of conductive material in the via 22 into the form shown in FIG. 2. However, it should be noted that other method could be used to separate the first conductive element 221, the second conductive element 222 and the ground element 223. In the present embodiment, the first conductive element 221 and the second conductive element 222 are quadrants of a circle when viewed from the top view and the area of the quadrants are approximately equal. The ground element 223 is a semicircle with an area equal to the area of the first conductive element 221 and the second conductive element 222 combined. However, it should be noted that the first conductive element 221, the second conductive element 222 and the ground element 223 could be partitioned into other forms.

The first circuit 23 is located on the surface layer 211 of the substrate body 21. The first circuit 23 is connected to the first conductive element 221 and is used for transmitting a positive differential signal. The second circuit 24 is located on the surface layer 211 of the substrate body 21. The second circuit 24 is connected to the second conductive element 222 and is used for transmitting a negative differential signal.

One of the advantages of the present invention is the production of three conductive elements inside one via (that is, the via 22). Two of the conductive elements (the first conductive element 221 and the second conductive element 222) can be respectively used to transmit a positive and a negative differential signal. The other conductive element (the ground element 223) is connected to a ground signal to serve as a reference plane for the impedance design. Thus, not only is the purpose of controlling the impedance inside the via achieved, but the effect is so positive that the electrical characteristics of the differential pair are also improved. In addition, one via (the via 22) instead of multiple vias is used to transmit a differential pair of signals in the present invention. Hence, the area occupied by the via is effectively reduced.

FIG. 3 is a diagram of a semiconductor substrate for transmitting a differential pair according to a second embodiment of the present invention. The semiconductor substrate 3 includes a substrate body 21, at least one via 22, a first circuit 23 and a second circuit 24. The substrate body 21 has a surface layer 211, a ground layer 212 and a plurality of dielectric layers 213. The ground layer 212 can be fully or partially distributed between two dielectric layers 213. The via 22 has a first conductive element 221, a second conductive element 222 and a ground element 223 therein. The ground element 223 includes a third conductive element 224 and a fourth conductive element 225. The first conductive element 221, the second conductive element 222, the third conductive element 224 and the fourth conductive element 225 are separate and electrically isolated to one another. The third conductive element 224 and the fourth conductive element 225 are electrically connected to the ground layer 212 of the substrate body 21. The first conductive element 221 and the second conductive element 222 pass through the ground layer 212 of the substrate body 21 and are electrically isolated with the ground layer 212 of the substrate body 21.

In the present embodiment, the method of forming the first conductive element 221, the second conductive element 222, the third conductive element 224 and the fourth conductive element 225 includes, for example, by laser cutting. However, it should be noted that other method could be used to separate the first conductive element 221, the second conductive element 222, the third conductive element 224 and the fourth conductive element 225. In the present embodiment, the first conductive element 221, the second conductive element 222, the third conductive element 224 and the fourth conductive element 225 are quadrants of a circle when viewed from the top view and the area of the quadrants are approximately equal. However, it should be noted that the first conductive element 221, the second conductive element 222, the third conductive element 224 and the fourth conductive element 225 could be partitioned into other forms.

The first circuit 23 is located on the surface layer 211 of the substrate body 21. The first circuit 23 is connected to the first conductive element 221 and is used for transmitting a positive differential signal. The second circuit 24 is located on the surface layer 211 of the substrate body 21. The second circuit 24 is connected to the second conductive element 222 and is used for transmitting a negative differential signal.

It should be noted that a better impedance control could be achieved because the semiconductor substrate 3 of the present embodiment has two ground elements (that is, the third conductive element 224 and the fourth conductive element 225).

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.

Claims

1. A semiconductor substrate for transmitting a differential pair, comprising: a substrate body, having at least one surface layer and one ground layer;at least one via, having an opening on the surface layer of the substrate body and having a first conductive element, a second conductive element and at least one ground element therein, wherein the first conductive element, the second conductive element and the ground element are electrically isolated to one another, the ground element is electrically connected to the ground layer of the substrate body, and the first conductive element and the second conductive element pass through the ground layer of the substrate body and are electrically isolated with the ground layer of the substrate body;a first circuit, located on the surface layer of the substrate body, wherein the first circuit is connected to the first conductive element and is used for transmitting a positive differential signal; anda second circuit, located on the surface layer of the substrate body, wherein the second circuit is connected to the second conductive element and is used for transmitting a negative differential signal.

2. The semiconductor substrate according to claim 1, wherein the via is a blind via.

3. The semiconductor substrate according to claim 1, wherein the via is a through via.

4. The semiconductor substrate according to claim 1, wherein an area of the first conductive element from the top view is identical to an area of the second conductive element from the top view, and an area of the ground element from the top view is substantially equal to the sum of the area of the first conductive element and the second conductive element from the top view.

5. The semiconductor substrate according to claim 1, wherein the ground element comprises a third conductive element and a fourth conductive element, and the third conductive element and the fourth connective element are electrically isolated to each other but are electrically connected to the ground layer of the substrate body.

6. The semiconductor substrate according to claim 5, wherein, from the top view, an area of the first conductive element, an area of the second conductive element, an area of the third conductive element and an area of the fourth conductive element are identical.

7. The semiconductor substrate according to claim 1, wherein the substrate body further comprises a plurality of dielectric layers, and the ground layer is distributed between two dielectric layers.