Semiconductor devices including compressive stress patterns and methods of fabricating the same
Provided is a method of fabricating a semiconductor device. Gate patterns are formed on a substrate including an NMOS transistor region and a PMOS transistor region. A spacer structure is formed on sidewalls of the gate patterns. The substrate in the PMOS transistor region is etched using the gate patterns and the spacer structure as etching masks, and thereby a recessed region is formed. A compressive stress pattern is formed in the recessed region, and a sidewall of the compressive stress pattern protrudes upwardly from an upper surface of the substrate. A mask oxide layer is formed on a sidewall of the spacer structure. The mask oxide layer is formed to cover a portion of the sidewall of the compressive stress pattern that protrudes upwardly from the upper surface of the substrate.
1. A method of fabricating a semiconductor device, the method comprising:
forming gate patterns in an NMOS transistor region and a PMOS transistor region of a substrate;
forming a spacer structure on sidewalls of the gate patterns;
etching the substrate in the PMOS transistor region using the gate patterns and the spacer structure as etching masks, thereby forming a recessed region;
forming a compressive stress pattern in the recessed region, wherein a sidewall of the compressive stress pattern protrudes upwardly from an upper surface of the substrate;
forming a mask oxide layer on a sidewall of the spacer structure, wherein the mask oxide layer covers a portion of the sidewall of the compressive stress pattern that protrudes upwardly from the upper surface of the substrate;
forming a metal-semiconductor compound layer on the compressive stress pattern; and
removing the mask oxide layer from the sidewall of the spacer structure after forming the metal-semiconductor compound layer.
2. The method of claim 1 , wherein an upper surface of the compressive stress pattern is higher than the upper surface of the substrate, and the sidewall of the compressive stress pattern is declined from the upper surface of the compressive stress pattern toward the gate patterns.
3. The method of claim 1 , further comprising:
wherein removing the mask oxide layer comprises:
transforming the mask oxide layer into a first ammonium fluorosilicate layer; and
removing the first ammonium fluorosilicate layer.
4. The method of claim 3 , wherein transforming the mask oxide layer into the first ammonium fluorosilicate layer is performed by exposing the mask oxide layer to a source gas including NH 3 , and wherein the source gas further comprises at least one of HF or NF 3 .
5. The method of claim 3 , wherein removing the first ammonium fluorosilicate layer comprises annealing the substrate having the first ammonium fluorosilicate layer at a temperature of about 100° C. to about 200° C.
6. The method of claim 3 , wherein forming the spacer structure comprises sequentially forming a first nitride layer and a first oxide layer on the sidewalls of the gate patterns;
wherein the first nitride layer comprises a sidewall portion extending along a sidewall of the first oxide layer and a bottom portion extending between the upper surface of the substrate and a lower surface of the first oxide layer.
7. The method of claim 6 , wherein forming the spacer structure further comprises:
forming a second nitride layer between the gate patterns and the first nitride layer; and
forming a second oxide layer between the first nitride layer and the second nitride layer.
8. The method of claim 3 , further comprising forming a tensile stress pattern on the substrate after removing the mask oxide layer.
9. A method of fabricating a semiconductor device, the method comprising:
forming a gate pattern on a substrate;
forming spacers on sidewalls of the gate pattern;
etching the substrate adjacent the gate pattern using the gate pattern and the spacers as an etching mask, thereby forming recessed regions in the substrate adjacent the gate pattern;
forming compressive stress patterns in the recessed regions, wherein sidewalls of the compressive stress patterns facing the gate pattern protrude upwardly from an upper surface of the substrate;
forming a mask layer on sidewalls of the spacers and on the portions of the sidewalls of the compressive stress patterns that protrude upwardly from an upper surface of the substrate;
forming metal-semiconductor layers on the compressive stress patterns; and
removing the mask layer from the sidewalls of the spacers after forming the metal-semiconductor layers.
10. The method of claim 9 , wherein forming the mask layer comprises forming a preliminary mask layer on the sidewalls of the spacers and on the compressive stress patterns, and selectively removing a portion of the preliminary mask layer from upper surfaces of the compressive stress patterns, and wherein forming the metal-semiconductor layers on the compressive stress patterns comprises forming the metal-semiconductor layers on the upper surfaces of the compressive stress patterns.
11. The method of claim 10 , wherein the spacers comprise first spacers on the gate pattern and second spacers on the first spacers, wherein the first spacers comprise a nitride and wherein the second spacers and the mask layer comprise oxides.
12. The method of claim 11 , further comprising transforming the mask layer into a first ammonium fluorosilicate layer, and transforming the second spacers into a second ammonium fluorosilicate layer, and removing the first ammonium fluorosilicate layer and the second ammonium fluorosilicate layer.
13. The method of claim 9 , further comprising forming source/drain extensions in the substrate beneath the spacers, wherein the compressive stress patterns contact the source/drain extensions.