Semiconductor device and method of manufacturing the same

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

forming an etching-back layer formed of a second material on a supporting substrate formed of a first material, said second material being different in etching rate from said first material;

forming a multilayer wiring board on said etching-back layer;

etching said etching-back layer to separate said supporting substrate from said multilayer wiring board;

mounting a semiconductor chip on said multilayer wiring board; and

forming an intermediate layer on said etching-back layer between the steps of forming said etching-back layer and forming said multilayer wiring board, so that said multilayer wiring board is laminated on said etching-back layer, wherein said intermediate layer is etched with the etching of said etching-back layer.

2. The method of manufacturing a semiconductor device according to claim 1 , wherein said second material is Al, Al alloy, Cu, or Cu alloy.

3. The method of manufacturing a semiconductor device according to claim 1 , wherein the step of forming said multilayer wiring board comprises the steps of:

forming an outer electrode pad on said etching-back layer;

forming an insulating layer so as to bury the outer electrode pad;

forming an opening at at least a part of the insulating layer just above said outer electrode pad; and

forming an inner electrode pad connected to said outer electrode pad through said opening on said insulating layer.

4. The method of manufacturing a semiconductor device according to claim 3 , wherein the step of forming said multilayer wiring board further comprises the step of forming one or a plurality of wiring layer, the step of forming each of wiring layer comprises the steps of:

forming wiring connected to said outer electrode pad through said opening on said insulating layer;

forming another insulating layer so as to burry said wiring; and

forming another opening at a part of said another insulating layer just above said wiring, said inner electrode pad being formed on said another insulating layer and connected to said wiring through said another opening.

5. The method of manufacturing a semiconductor device according to claim 1 , further comprising a step of attaching a reinforcing plate for reinforcing said multilayer wiring board.

6. The method of manufacturing a semiconductor device according to claim 5 , wherein the attachment of said reinforcing plate is carried out before said etching, and said reinforcing plate is attached to an opposite surface of said multilayer wiring board to the surface on said etching-back layer side.

7. The method of manufacturing a semiconductor device according to claim 5 , wherein the attachment of said reinforcing plate is carried out after said etching.

8. The method of manufacturing a semiconductor device according to claim 1 , wherein said etching-back layer is etched by wet etching in the step of etching said etching-back layer.

9. The method of manufacturing a semiconductor device according to claim 8 , wherein said first material is a material, which is not substantially etched by etchant used in said etching step.

10. The method of manufacturing a semiconductor device according to claim 9 , wherein said first material is a kind of metal or alloy selected from a group consisting of Si, Ti alloy, stainless steel, duralumin, and malaging steel.

11. The method of manufacturing a semiconductor device according to claim 9 , wherein said first material is a kind of inorganic ceramic material selected from a group consisting of alumina, mullite, and aluminum nitride.

12. The method of manufacturing a semiconductor device according to claim 9 , wherein said first material is polyimide.

13. The method of manufacturing a semiconductor device according to claim 8 , wherein the surface on said etching-back layer side of said multilayer wiring board is formed of a material, which is not substantially etched with etchant used in said etching step.

14. A method of manufacturing a semiconductor device, comprising the steps of:

forming an etching-back layer formed of a second material on a supporting substrate formed of a first material, said second material being different in etching rate from said first material;

forming a multilayer wiring board on said etching-back layer;

etching said etching-back layer to separate said supporting substrate from said multilayer wiring board;

mounting a semiconductor chip on said multilayer wiring board; and

forming a penetrating layer having higher liquid-permeability than that of said etching-back layer, on said etching-back layer between the steps of forming said etching-back layer and forming said multilayer wiring board.

15. The method of manufacturing a semiconductor device according to claim 14 , further comprising a step of forming another etching-back layer formed of said second material on said penetrating layer between the steps of forming said penetrating layer and forming said multilayer wiring board.

16. The method of manufacturing a semiconductor device according to claim 14 , wherein said penetrating layer is formed of a porous material.

17. A method of manufacturing a semiconductor device, comprising the steps of:

forming an etching-back layer formed of a second material on a supporting substrate formed of a first material, said second material being different in etching rate from said first material;

forming a multilayer wiring board on said etching-back layer;

etching said etching-back layer by wet etching to separate said supporting substrate from said multilayer wiring board;

mounting a semiconductor chip on said multilayer wiring board; and

forming a penetrating layer having higher liquid-permeability than that of said etching-back layer on said supporting substrate before the step of forming said etching-back layer.

18. A method of manufacturing a semiconductor device, comprising the steps of:

forming an etching-back layer formed of a second material on a supporting substrate formed of a first material, said second material being different in etching rate from said first material;

forming a multilayer wiring board on said etching-back layer;

etching said etching-back layer by wet etching to separate said supporting substrate from said muhilayer wiring board; and

mounting a semiconductor chip on said multilayer wiring board, wherein said etching-back layer is formed on each of both front and back surfaces of said supporting substrate, and said multilayer wiring board is formed on each of said etching-back layers formed on the both front and back surfaces of said supporting substrate, and said etching-back layers formed on the both front and back surfaces of said supporting substrate are etched together in said step of etching.

19. A method of manufacturing a semiconductor device comprising the steps of:

forming an etching-back layer formed of a second material on a supporting substrate formed of a first material, said second material being different in etching rate from said first material;

forming a multilayer wiring board on said etching-back layer;

etching said etching-back layer to separate said supporting substrate from said multilayer wiring board;

mounting a plurality of semiconductor chips on said multilayer wiring board;

separating said multilayer wiring board between every said semiconductor chip; and

forming an intermediate layer on said etching-back layer between the steps of forming said etching-back layer and forming said multilayer wiring board, so that said multilayer wiring board is laminated on said etching-back layer, wherein said intermediate layer is etched with the etching of said etching-back layer.