Semiconductor device and manufacturing method thereof

1. A method of manufacturing a semiconductor device, comprising:

forming an opening in a first substrate;

forming a stopper layer on a surface of the first substrate in a region surrounding the opening;

forming a first metal in the opening and on the stopper layer;

polishing the first metal with a first chemical mechanical polishing and stopping on the stopping layer to form a first connection electrode in the first substrate;

polishing the first substrate using a second chemical mechanical polishing in which a polishing rate of the first metal is less than that of a region surrounding the first connection electrode thereby causing the first connection electrode to protrude from the first substrate;

stacking the first substrate and a second substrate that includes a second connection electrode such that the first and second connection electrodes face each other; and

diffusion-bonding the first and second connection electrodes to each other by pressing and heating the first and second substrates to a temperature at or below the melting point of the first metal.

2. The method of claim 1 , wherein the opening in the first substrate is a through-substrate-via.

3. The method of claim 1 , wherein the temperature is below the melting point of the first metal.

4. The method of claim 1 , wherein the diffusion-bonding is performed at 100° C. or more and 500° C. or less.

5. The method of claim 1 , wherein the second connection electrode has a bonding surface that has a concave shape.

6. The method of claim 1 , further comprising:

forming an opening in the second substrate;

filling the opening in the second substrate with a second metal to form the second connection electrode; and

polishing the second substrate using chemical mechanical polishing, the second metal having a polishing rate that is less than a polishing rate of a region surrounding the second metal, the chemical mechanical polishing thereby causing the second connection electrode to protrude from the second substrate;

wherein the temperature used for bonding the first and second substrates is at or below a melting point of the second metal.

7. The method of claim 6 , wherein the first and second metal are the same metal.

8. The method of claim 1 , further comprising:

forming an opening in the second substrate;

filling the opening in the second substrate with a second metal;

polishing the second substrate using chemical mechanical polishing that causes an upper surface of the second metal to form a concave shape;

depositing a third metal on the upper surface of the second metal to fill the concave shape and form the second connection electrode;

polishing the second substrate using chemical mechanical polishing that causes an upper surface of the third metal to be a planar; and

bonding the first and second connection electrode by pressing and heating the first and second substrates to a temperature at or below the melting point of the first metal, a melting point of the second metal, and a melting point of the third metal.

9. The method of claim 1 , further comprising:

bombarding an upper surface of the first connection electrode with argon after polishing the first substrate using the second chemical mechanical polishing.

10. The method of claim 1 , wherein the second chemical mechanical polishing is performed using a polishing pad with hardness of 30 MPa or less.

11. A method of bonding substrates, comprising:

forming a first connection electrode in a first substrate by forming an opening in the first substrate, forming a stopper layer on the first substrate in a region surrounding the opening, forming a first metal in the opening and on the stopper layer, polishing the first metal using a first chemical mechanical polishing and stopping on the stopper layer;

polishing the first substrate using a second chemical mechanical polishing in which a polishing rate of the first metal is less than a polishing rate of a region surrounding the first connection electrode, the second chemical mechanical polishing thereby causing the first connection electrode to protrude from of the first substrate;

forming a second connection electrode in a second substrate, the second connection electrode comprising a second metal;

stacking the first and second substrates so that the first and second connection electrodes are opposed;

pressing the first and second substrates so that the first and second connection electrodes are in contact; and

heating the first and second substrates to a temperature at or below a melting point of the first metal and at or below a melting point of the second metal.

12. The method of claim 11 , wherein the pressing and heating steps occur at a same time.

13. The method of claim 11 , wherein the first connection electrode protrudes from a front-side surface of the first substrate and the second connection electrode is formed on a back-side surface of the second substrate.

14. The method of claim 11 , wherein the first and second metals are the same metal.

15. The method of claim 11 , wherein the first and second metals are diffusion bonded by pressing and heating the first and second substrates.

16. The method of claim 11 , wherein the first metal comprises copper.

17. The method of claim 11 , wherein the second chemical mechanical polishing is performed using a slurry comprising a silica dispersion including potassium hydroxide and a polishing pad with a hardness of 30 MPa or less.

18. The method of claim 11 , wherein the second connection electrode has a concave-shaped bonding surface.

19. The method of claim 1 , wherein the first substrate includes an insulating film.

20. The method of claim 11 , wherein the first substrate includes an insulating film.

21. A method of manufacturing a semiconductor device, comprising:

forming an opening in a first substrate;

filling the opening in the first substrate with a first metal to form a first connection electrode;

polishing the first substrate using chemical mechanical polishing, a polishing rate of the first metal is less than that of a region surrounding the first metal, the chemical mechanical polishing thereby causing the first connection electrode to protrude from a surface of the first substrate;

stacking the first substrate and a second substrate that includes a second connection electrode such that the first and second connection electrodes face each other; and

diffusion-bonding the first and second connection electrodes to each other by pressing and heating the first and second substrates to a temperature at or below the melting point of the first metal,

wherein the chemical mechanical polishing is performed using a polishing pad with hardness of 30 MPa or less.