Reduction of memory instability by local adaptation of re-crystallization conditions in a cache area of a semiconductor device
View Patent ↗By appropriately locally controlling the conditions during a re-growth process in a memory region and a speed-critical device region, the creation of dislocation defects may be reduced in the memory region, thereby enhancing overall stability of respective memory cells. On the other hand, enhanced strain levels may be obtained in the speed-critical device region by performing an efficient amorphization process and re-crystallizing amorphized portions, for instance, in the presence of a rigid material to provide a desired high strain level.
1. A method, comprising:
selectively performing a pre-amorphization process for drain and source regions of a plurality of first N-channel transistors in a first device region using non-dopant ions, while masking a plurality of first P-channel transistors in said first device region and masking a plurality of second P-channel transistors and a plurality of second N-channel transistors formed in a memory device region of a semiconductor device;
performing a second pre-amorphization process selectively for said second N-channel transistors, wherein said second pre-amorphization process comprises an implantation step using a tilt angle;
annealing said first and second P-channel transistors and said second N-channel transistors in the presence of a rigid material layer formed above said first device region to re-crystallize said first N-channel transistors in a strained state; and
providing a strain-inducing mechanism in said first device region and said memory device region to induce strain in said first and second P-channel transistors and second N-channel transistors.
2. The method of claim 1 , wherein providing said strain-inducing mechanism comprises forming a stressed dielectric material above said first device region and said memory device region after annealing said first and second P-channel transistors and said second N-channel transistors.
3. The method of claim 1 , wherein said rigid material layer is provided above said first device region and said memory device region.
4. The method of claim 1 , further comprising forming said rigid material layer above said first device region and said memory device region and selectively removing said rigid material layer from above said memory device region prior to annealing said first and second P-channel transistors and N-channel transistors.
5. A method, comprising:
performing a first amorphization process for a plurality of first N-channel transistors of a first device region of a semiconductor device using non-dopant ions;
performing a second amorphization process for a plurality of second N-channel transistors of a memory device region using non-dopant ions, while masking said first device region, said second amorphization process comprising an implantation step using a tilt angle;
annealing said first and second N-channel transistors; and
forming a stressed dielectric material above said first and second N-channel transistors, said stressed dielectric material inducing a tensile strain in a channel region of said first and second N-channel transistors.
6. The method of claim 5 , wherein said first amorphization process is performed for said first and second N-channel transistors in a common process.
7. The method of claim 5 , wherein performing said first and second amorphization processes comprises masking P-channel transistors in said first device region and said memory device region.
8. The method of claim 5 , wherein performing said first amorphization process comprises masking said memory device region prior to introducing an amorphizing species into said first N-channel transistors.
9. The method of claim 5 , further comprising forming a rigid material layer above said first device region and said memory device region and annealing said first and second N-channel transistors in the presence of said rigid material layer.
10. The method of claim 9 , further comprising at least partially removing said rigid material layer from said first device region and said memory device region prior to forming said stressed dielectric material.
11. The method of claim 5 , wherein said second device region represents a static RAM area of a CPU.
12. The method of claim 11 , wherein said first device region represents a logic block.
13. The method of claim 5 , wherein said first N-channel transistors have an SOI configuration.
14. A method, comprising:
forming a plurality of first N-channel transistors in a first device region above a first initially crystalline semiconductor layer, said first N-channel transistors defining a first length direction, said first length direction being oriented along a predefined crystalline direction defined by a first set of Miller indices, said predefined crystalline direction being substantially equivalent to a surface orientation of said first crystalline semiconductor layer that is defined by a set of Miller indices that differs from said first set;
forming a plurality of second N-channel transistors in a memory device region above a second initially crystalline semiconductor layer, said second N-channel transistors defining a second length direction, said second length direction being oriented along a predefined crystalline direction defined by a second set of Miller indices, said predefined crystalline direction being substantially equivalent to a surface orientation of said second crystalline semiconductor layer that is defined by the second set of Miller indices;
performing an amorphization implantation process for forming a substantially amorphized portion in drain and source areas of at least said first N-channel transistors; and
re-crystallizing said substantially amorphized portion of said first N-channel transistors.
15. The method of claim 14 , wherein performing said amorphization implantation process includes forming substantially amorphized portions in drain and source areas of said second N-channel transistors.
16. The method of claim 14 , further comprising forming a rigid material layer above said first device region and said memory device region and re-crystallizing said portions in the presence of said rigid material layer.
17. The method of claim 16 , further comprising at least partially removing said rigid material layer.
18. The method of claim 14 , wherein said first length direction differs from said second length direction.
19. The method of claim 14 , wherein said first length direction is collinear to said second length direction and said first and second crystalline semiconductor layers have different crystallographic orientations.