Through silicon via and redistribution layer

1. A semiconductor device comprising:

a silicon substrate having a front surface and a back surface;

a plurality of metal layers comprising a first metal layer located on said front surface and connected to a plurality of doped regions on the front surface of the silicon substrate to form a plurality of semiconductor structures of the semiconductor device;

a through silicon via (TSV) extending through said silicon substrate from said back surface to said front surface, wherein said TSV is directly connected at one end to said first metal layer; and

a redistribution layer (RDL) connected to another end of said TSV, wherein said RDL is embedded in said silicon substrate by being located in trenches in said back surface of said silicon substrate.

2. A semiconductor device according to claim 1 , wherein said TSV comprises a hole and a layer of copper, and wherein said layer of copper does not completely fill said hole.

3. A semiconductor device according to claim 1 , wherein said TSV comprises a layer stack comprising at least an isolation layer and a barrier layer coating the walls of said hole and separating said copper layer from said silicon substrate.

4. A semiconductor device according to claim 1 , further comprising a protection layer covering copper in said RDL and TSV.

5. A semiconductor device according to claim 4 , wherein said protection layer comprises at least one passivation layer.

6. A semiconductor device according to claim 1 , wherein said semiconductor device is a complementary metal oxide semiconductor (CMOS) device and/or a Micro Electrical Mechanical Systems (MEMS) device.

7. A method of forming a semiconductor device, the method comprising:

providing a silicon substrate having a front surface and a back surface;

forming a plurality of layers comprising a first metal layer on said front surface and connected to a plurality of doped regions on the front surface of the silicon substrate to form a plurality of semiconductor structures of the semiconductor device;

forming a through silicon via (TSV) extending through said silicon substrate from the back surface to the front surface, wherein said TSV is directly connected at one end to said first metal layer; and

forming a redistribution layer (RDL) connected to another end of said TSV, wherein said RDL is embedded in said silicon substrate, wherein said step of forming said RDL comprises etching trenches in said back surface of said silicon substrate for forming metal lines and/or metal pads of said RDL.

8. A method according to claim 7 , wherein said step of forming the TSV comprises:

etching a trench in said silicon substrate for forming a connection pad of said TSV;

etching a hole through said silicon substrate to said first metal layer;

depositing a copper layer in said trench and in said hole to form said TSV, wherein said copper layer does not completely fill said hole.

9. A method according to claim 8 , wherein said step of forming said TSV further comprises, before said step of depositing said copper layer, providing a layer stack comprising at least an isolation layer and a barrier layer coating the walls of said hole.

10. A method according to claim 8 , wherein said step of depositing copper comprises performing electrochemical deposition (ECD).

11. A method according to claim 7 , wherein said step of forming said RDL comprises:

filling said trenches with copper.

12. A method according to claim 7 , further comprising performing a wet etch to remove excess copper.

13. A method according to claim 7 , further comprising providing a protection layer covering copper in said RDL and TSV.

14. A method according to claim 13 , wherein said step of providing a protection layer comprises depositing at least one passivation layer.

15. A method according to claim 7 , wherein said first metal layer is in a backend stack of said semiconductor device.

16. A method according to claim 7 , forming a semiconductor device comprises forming a complementary metal oxide semiconductor (CMOS) device and/or a Micro Electrical Mechanical Systems (MEMS) device.