Semiconductor device including a substrate contact plug and manufacturing method thereof

1. A semiconductor device, comprising:

a semiconductor substrate which includes a first region, a second region surrounding the first region in plan view, and a scribe region on a side of the second region opposite the first region in plan view;

a plurality of elements which are formed near an upper surface of the semiconductor substrate in the first region and forms part of a first circuit;

an element isolation portion which is buried in a first trench formed in the upper surface of the semiconductor substrate and isolates the plurality of elements from each other;

second trenches which are formed in the upper surface of the semiconductor substrate in the first region and in the second region, respectively, and are deeper than the first trench;

a first wiring which is formed over the semiconductor substrate in the first region via an interlayer insulating film and forms part of the first circuit;

a second wiring which is formed over the semiconductor substrate in the second region via the interlayer insulating film and does not form part of any circuit;

a first conductive connection portion which penetrates the interlayer insulating film and is connected to at least one of the plurality of elements;

a second conductive connection portion which is buried in the second trench in the first region and is connected to the semiconductor substrate at a bottom of the second trench in the first region; and

at least one third conductive connection portion, each being buried in a respective one of the second trenches in the second region and does not form part of any circuit,

wherein an upper surface of the second conductive connection portion is connected to the first wiring,

wherein an upper surface of the third conductive connection portion is connected to the second wiring, and

wherein each third conductive connection portion in the second region is disposed adjacent to the scribe region in plan view.

2. The semiconductor device according to claim 1 ,

wherein widths of the second conductive connection portion and the at least one third conductive connection portion each are larger than a width of the first conductive connection portion in a direction along the upper surface of the semiconductor substrate.

3. The semiconductor device according to claim 1 ,

wherein the at least one third conductive connection portion and the second wiring are formed in an annular shape so as to surround the first region in plan view.

4. The semiconductor device according to claim 1 ,

wherein the at least one third conductive connection portion comprises a plurality of third conductive connection portions, and

wherein the plurality of third conductive connection portions are arranged in the second region.

5. The semiconductor device according to claim 1 ,

wherein the semiconductor substrate includes:

a substrate; and

an insulating film and a semiconductor layer which are sequentially formed on the substrate, and

wherein the second conductive connection portion and the at least one third conductive connection portion penetrate the insulating film.

6. The semiconductor device according to claim 1 , further comprising:

a fourth conductive connection portion which is formed at a position that, in plan view, does not overlap with the second trench in the second region and penetrates the interlayer insulating film,

wherein the fourth conductive connection portion does not form part of any circuit, and

wherein a width of the fourth conductive connection portion is larger than a width of the first conductive connection portion in a direction along the upper surface of the semiconductor substrate.

7. The semiconductor device according to claim 4 ,

wherein some of the plurality of third conductive connection portions are formed in an annular shape so as to surround the first region in plan view, and

wherein others of the plurality of third conductive connection portions are discretely arranged around the first region in plan view.

8. The semiconductor device according to claim 1 , wherein, in plan view, each part of the at least one third conductive connection portion extends in a direction along which an adjacent part of the scribe region extends.

9. The semiconductor device according to claim 1 , wherein, in plan view:

the scribe region defines an outer periphery of a semiconductor chip having the first and second regions; and

the second region is adjacent to said outer periphery and is constructed as a seal ring region for said semiconductor chip.

10. The semiconductor device according to claim 1 , wherein, in plan view:

the scribe region has an annular shape;

each third conductive connection portion has an annular shape and is surrounded by the scribe region; and

the annular shape of each third conductive connection portion is centered with respect to the annular shape of the scribe region.

11. The semiconductor device according to claim 1 , wherein another element isolation portion is buried in a first trench formed in the upper surface of the semiconductor substrate in the scribe region.

12. The semiconductor device according to claim 1 , wherein:

the second conductive connection portion forms a substrate contact plug; and

the at least one third conductive connection portion forms a dummy substrate contact plug.