Semiconductor device and method for manufacturing the same
The present invention provides a method for manufacturing a semiconductor device, which comprises: providing an SOI substrate, which comprises a base layer, an insulating layer located on the base layer and a active layer located on the insulating layer; forming a gate stack on the SOI substrate; etching the active layer, the insulating layer and a part of the base layer of the SOI substrate with the gate stack as a mask, so as to form trenches on both sides of the gate stack; forming a crystal dielectric layer within the trenches, wherein the upper surface of the crystal dielectric layer is lower than the upper surface of the insulating layer and not lower than the lower surface of the insulating layer; and forming source/drain regions on the crystal dielectric layer. The present invention further provides a semiconductor device. The present invention is capable of eliminating pathway for leakage current between source/drain regions and SOI substrate at the meantime of reducing contact resistance at source/drain regions.
1. A method for manufacturing a semiconductor device, comprising:
(a) providing an SOI substrate ( 100 ), which comprises a base layer ( 101 ), an insulating layer ( 102 ) located on the base layer ( 101 ) and a active layer ( 103 ) located on the insulating layer ( 102 );
(b) forming a gate stack on the SOI substrate ( 100 );
(c) etching the active layer ( 103 ), the insulating layer ( 102 ) and a part of the base layer ( 101 ) of the SOI substrate ( 100 ) with the gate stack as a mask, so as to form trenches ( 104 ) on both sides of the gate stack;
(d) forming a crystal dielectric layer ( 105 ) within the trenches ( 104 ), wherein an upper surface of the crystal dielectric layer ( 105 ) is lower than an upper surface of the insulating layer ( 102 ) and not lower than a lower surface of the insulating layer ( 102 ); and
(e) forming source/drain regions ( 107 ) on the crystal dielectric layer ( 105 ).
2. The method of claim 1 , wherein after the step (b), the method further comprises: (f) forming spacers ( 240 ) on sidewalls of the gate stack.
3. The method of claim 1 , wherein the thickness of the active layer ( 103 ) of the SOI substrate ( 100 ) is less than 10 nm.
4. The method of claim 1 , further comprising forming raised source/drain regions ( 108 ) after formation of the source/drain regions ( 107 ).
5. The method of claim 1 , wherein:
the trenches ( 104 ) are embedded into the base layer ( 101 ) for about 100 nm to 1 μM.
6. The method of claim 5 , further comprising forming the trenches ( 104 ) having a Sigma shape on sidewalls of the active layer ( 103 ).
7. The method of claim 1 , wherein the step for forming a crystal dielectric layer ( 105 ) within the trenches ( 104 ) comprises:
forming a crystal insulating material ( 105 ′) within the trenches ( 104 ) by means of epitaxial growth or solid-phase transformation, wherein an upper surface of the crystal insulating material ( 105 ′) is not higher than a bottom of the gate stack; and
etching the crystal insulating material ( 105 ′) to form the crystal dielectric layer ( 105 ) by means of dry etching and/or wet etching.
8. The method of claim 7 , wherein:
a material for the crystal dielectric layer ( 105 ) comprises any one of Gd 2 O 3 , TrHfO 4 and Nd 2 O 3 , or combinations thereof, or other materials having a lattice constant close to that of the material for the base layer ( 101 ).
9. The method of claim 1 , wherein:
a lattice constant of the source/drain regions ( 107 ) is not equal to that of the active layer ( 103 ).
10. The method of claim 9 , wherein:
for N-type devices, the lattice constant of the source/drain regions ( 107 ) is smaller than that of the active layer ( 103 ); and for P-type devices, the lattice constant of the source/drain regions ( 107 ) is larger than that of the active layer ( 103 ).
11. The method of claim 9 , wherein:
the source/drain regions ( 107 ) comprises SiGe or Si:C.
12. A semiconductor device comprising:
an SOI substrate ( 100 ), which comprises a base layer ( 101 ), an insulating layer ( 102 ) located on the base layer ( 101 ) and a active layer ( 103 ) located on the insulating layer ( 102 );
a gate stack formed on the SOI substrate ( 100 );
source/drain regions ( 107 ) formed within the SOI substrate ( 100 ) on both sides of the gate stack, wherein the source/drain regions ( 107 ) penetrate through the active layer ( 103 ) and extend to between upper and lower surfaces of the insulating layer ( 102 ); and
a crystal dielectric layer ( 105 ) located entirely under the source/drain regions ( 107 ) and directly on the base layer ( 101 ).
13. The semiconductor device of claim 12 , further comprising:
spacers ( 240 ) formed on sidewalls of the gate stack.
14. The semiconductor device of claim 12 , wherein a thickness of the active layer ( 103 ) of the SOI substrate ( 100 ) is less than 10 nm.
15. The semiconductor device of claim 12 , wherein the source/drain regions ( 107 ) have a Sigma shape.
16. The semiconductor device of claim 12 , wherein the source/drain regions are raised source/drain regions.
17. The semiconductor device of claim 12 , wherein:
the crystal dielectric layer ( 105 ) is embedded into the base layer ( 101 ) for about 100 nm to 1 μm.
18. The semiconductor device of claim 17 , wherein:
a material for the crystal dielectric layer ( 105 ) comprises any one of Gd 2 O 3 , TrHfO 4 , Nd 2 O 3 or combinations thereof, or other materials whose lattice constant is close to that of the base layer ( 101 ).
19. The semiconductor device of claim 12 , wherein:
the source/drain regions ( 107 ) have a lattice constant not equal to that of the active layer ( 103 ).
20. The semiconductor device of claim 19 , wherein:
for N-type devices, the lattice constant of the source/drain regions ( 107 ) is smaller than that of the active layer ( 103 ); and for P-type devices, the lattice constant of the source/drain regions ( 107 ) is larger than that of the active layer ( 103 ).
21. The semiconductor device of claim 19 , wherein:
the source/drain regions ( 107 ) comprise SiGe or Si:C.