Semiconductor manufacturing process and apparatus for modifying in-film stress of thin films, and product formed thereby
An apparatus and process for depositing a barrier film on a substrate is disclosed. In particular, deposition of the barrier film is carried out on the substrate having an applied pressure. This applied pressure flexes the substrate to reduce in-plane stresses, wherein removal of the applied pressure after deposition of the barrier film modifies the in-film stress for the thin-film. With the above-described arrangement, it is possible to minimize the deterioration of electric characteristics of a semiconductor device and the occurrence of defects, such as film delamination, substrate cracks, and the like.
1. A method of modifying in-film stress of a thin barrier film, comprising:
preloading a substrate with a predetermined stress;
depositing a barrier material as a thin film on the substrate; and
unloading the predetermined stress applied to the substrate,
wherein said predetermined stress provides a mechanical stress s to said thin film, said mechanical stress being derived using the following equations:
s=s i +s T (1)
where s i is intrinsic stress calculated by the expression:
s i =[E s /6(1− n s )]( d s 2 /d f )(1 /R s −1 /R f ) (2)
where E s and n s are Young's modulus and Poisson ratio of said substrate, respectively, d s and d f are thickness of said substrate and said thin film, respectively, and R s and R f are radii of curvature of said substrate without and with said thin film, respectively, and where s T is thermal stress in said thin film calculated by the expression:
s T =[E f /(1 −n f )]( a f −a s )( T d −T M ) (3)
where E f and n f are Young's modulus and Poisson ratio for said thin film, respectively, a f and a s are average thermal coefficients of said thin film and said substrate, and T d and T M are film deposition temperature and temperature during stress measurement, respectively.
2. The method as recited by claim 1 , wherein the substrate is flexed by a retractable pin engaging the undersurface of the substrate to preload the substrate with the predetermined stress.
3. The method as recited by claim 1 , wherein the substrate is saddled over a pin and lowered to preload the substrate with a tensile stress.
4. The method as recited by claim 1 , wherein the substrate is squeezed to flex the substrate in a convex manner to preload the substrate with a tensile stress.
5. The method as recited by claim 1 , wherein the substrate is lowered by a vacuum to preload the substrate with a compressive stress.
6. The method as recited by claim 1 , wherein the thin film is provided using a deposition method selected from the group consisting of reactive ion sputtering, electron beam evaporation, physical vapor deposition (PVD), chemical vapor deposition CVD), atomic layer chemical vapor deposition (AL-CVD), and ion-beam assisted deposition (IAD) techniques.
7. The method as recited by claim 1 , wherein the thin film is selected from the group consisting of Ti, TiW, TiN, TaN, Ta-based materials, WN, MoN, AlN, CrN, SeN, barrier metals, and barrier metal alloys.
8. The method as recited by claim 1 , wherein the thin film is provided by growing a monolayer of the barrier material on the substrate.
9. A method for fabricating a thin-film structure body, comprising:
flexing a semiconductor substrate;
depositing a thin film of a barrier material on the flexed semiconductor substrate; and
unflexing the substrate, wherein said flexing said substrate provide a mechanical stress s to said thin film, said mechanical stress being derived using the following equations:
s=s i +s T (1)
where s i is intrinsic stress calculated by the expression:
s i =[E s /6(1− n s )]( d s 2 /d f )(1 /R s −1 /R f ) (2)
where E s and n s are Young's modulus and Poisson ratio of said substrate, respectively, d s and d f thickness of said substrate and said thin film, respectively, and R s and R f are radii of curvature of said substrate without and with said thin film, respectively, and where s T is thermal stress in said thin film calculated by the expression:
s T =[E f /(1 −n f )]( a f −a s )( T d −T M ) (3)
where E f and n f are Young's modulus and Poisson ratio for said thin film, respectively, a f and a s are average thermal coefficients of said thin film and said substrate, and T d and T M are film deposition temperature and temperature during stress measurement, respectively.
10. The method as recited by claim 9 , wherein said substrate is fixed by applying a pressure to a surface of the substrate.
11. The method as recited by claim 9 , wherein said flexing is carried out to preload a predetermined tensile stress.
12. The method as recited by claim 9 , wherein said flexing is carried out to preload a predetermined compressive stress.
13. A method for fabricating a thin-film structure body, comprising:
providing a substrate to a sample holder;
flexing the substrate to preload the substrate with tensile stress;
depositing a thin-film of a barrier material on the flexed substrate; and
unflexing the substrate, wherein said tensile stress of the substrate provides a mechanical stress s to said thin film, said mechanical stress being derived using the following equations:
s=s i +s T (1)
where s i is intrinsic stress calculated by the expression:
s i =[E s /6(1− n s )]( d s 2 /d f )(1 /R s −1 /R f ) (2)
where E s and n s are Young's modulus and Poisson ratio of said substrate, respectively, d s and d f are thickness of said substrate and said thin film, respectively, and R s and R f are radii of curvature of said substrate without and with said thin film, respectively, and where s T is thermal stress in said thin film calculated by the expression:
s T =[E f /(1 −n f )]( a f −a s )( T d −T M ) (3)
where E f and n f are Young's modulus and Poisson ratio for said thin film, respectively, a f and a s are average thermal coefficients of said thin film and said substrate, and T d and T M are film deposition temperature and temperature during stress measurement, respectively.
14. A method for fabricating a thin film structure body, comprising:
providing a substrate to a sample holder:
flexing the substrate to preload the substrate with compressive stress;
depositing a thin film of a barrier material on the flexed substrate; and
unflexing the substrate, wherein said compressive stress of the substrate provides a mechanical stress s to said thin film, said mechanical stress being derived using the following equations:
s=s i +s T (1)
where s i is intrinsic stress calculated by the expression:
s i =[E s /6(1− n s )]( d s 2 /d f )(1 /R s −1 /R f ) (2)
where E s and n s are Young's modulus and Poisson ratio of said substrate, respectively, d s and d f are thickness of said substrate and said thin film, respectively, and R s and R f are radii of curvature of said substrate without and with said thin film, respectively, and where s T is thermal stress in said thin film calculated by the expression:
s T =[E f /(1 −n f )]( a f −a s )( T d −T M ) (3)
where E f and n f are Young's modulus and Poisson ratio for said thin film, respectively, a f and a s are average thermal coefficients of said thin film and said substrate, and T d and T M are film deposition temperature and temperature during stress measurement, respectively.
15. A method of modifying in-film stress of a thin barrier film, comprising:
providing a substrate to a sample holder;
raising a pin to flex the substrate to preload the substrate with a predetermined tensile stress;
depositing a barrier material as a thin film on the substrate; and
lowering the pin to unload the tensile stress applied to the substrate, wherein said predetermined tensile stress of the substrate provides a mechanical stress s to said thin film, said mechanical stress being derived using the following equations:
s=s i +s T (1)
where s i is intrinsic stress calculated by the expression:
s i =[E s /6(1− n s )]( d s 2 /d f )(1 /R s −1 /R f ) (2)
where E s and n s are Young's modulus and Poisson ratio of said substrate, respectively, d s and d f are thickness of said substrate and said thin film, respectively, and R s and R f are radii of curvature of said substrate without and with said thin film, respectively, and where s T is thermal stress in said thin film calculated by the expression:
s T =[E f /(1 −n f )]( a f −a s )( T d −T M ) (3)
where E f and n f are Young's modulus and Poisson ratio for said thin film, respectively, a f and a s are average thermal coefficients of said thin film and said substrate, and T d and T M are film deposition temperature and temperature during stress measurement, respectively.
16. A method of modifying in-film stress of a thin barrier film, comprising:
providing a substrate to a sample holder;
applying a vacuum to flex the substrate to preload the substrate with a predetermined compressive stress;
depositing a barrier material as a thin film on the substrate; and
removing the vacuum to unload the compressive stress applied to the substrate, wherein said predetermined compressive stress of the substrate provides a mechanical stress s to said thin film, said mechanical stress being derived using the following equations:
s=s i +s T (1)
where s i is intrinsic stress calculated by the expression:
s i =[E s /6(1− n s )]( d s 2 /d f )(1 /R s −1 /R f ) (2)
where E s and n s are Young's modulus and Poisson ratio of said substrate, respectively, d s and d f are thickness of said substrate and said thin film, respectively, and R s and R f are radii of curvature of said substrate without and with said thin film, respectively, and where s T is thermal stress in said thin film calculated by the expression:
s T =[E f /(1 −n f )]( a f −a s )( T d −T M ) (3)
where E f and n f are Young's modulus and Poisson ratio for said thin film, respectively, a f and a s are average thermal coefficients of said thin film and said substrate, and T d and T M are film deposition temperature and temperature during stress measurement, respectively.
17. A method for fabricating a thin-film structure body, comprising:
mounting a substrate by clips to a sample holder;
situating said sample holder in a deposition chamber;
pumping the deposition chamber to a predetermined base pressure;
heating the substrate to a desired temperature:
raising a pin to flex the substrate to preload the substrate with tensile stress;
depositing a thin film of a barrier material on the flexed substrate; and
lowering the pin to unflex the substrate, wherein said tensile stress of the substrate provides a mechanical stress s to said thin film, turn said mechanical stress being derive using the following equations:
s=s i +s T (1)
where s i is intrinsic stress calculated by the expression:
s i =[E s /6(1− n s )]( d s 2 /d f )(1 /R s −1 /R f ) (2)
where E s and n s are Young's modulus and Poisson ratio of said substrate, respectively, d s and d f are thickness of said substrate and said thin film, respectively, and R s and R f are radii of curvature of said substrate without and with said thin film, respectively, and where s T is thermal stress in said thin film calculated by the expression:
s T =[E f /(1 −n f )]( a f −a s )( T d −T M ) (3)
where E f and n f are Young's modulus and Poisson ratio for said thin film, respectively, a f and a s are average thermal coefficients of said thin film and said substrate, and T d and T M are film deposition temperature and temperature during stress measurement, respectively.
18. A method for fabricating a thin-film structure body, comprising:
mounting a substrate by clips to a sample holder;
situating said sample holder in a deposition chamber;
pumping the deposition chamber to a predetermined base pressure;
heating the substrate to a desired temperature;
applying a vacuum to flex the substrate to preload the substrate with compressive stress;
depositing a thin film of a barrier material on the flexed substrate; and
removing the vacuum to unflex the substrate, wherein said compressive stress of the substrate provides a mechanical stress s to said thin film, said mechanical stress being derived using the following equations:
s=s i +s T (1)
where s i is intrinsic stress calculated by the expression:
s i =[E s /6(1− n s )]( d s 2 /d f )(1 /R s −1 /R f ) (2)
where E s and n s are Young's modulus and Poisson ratio of said substrate, respectively, d s and d f are thickness of said substrate and said thin film, respectively, and R s and R f are radii of curvature of said substrate without and with said thin film, respectively, and where s T is thermal stress in said thin film calculated by the expression:
s T =[E f /(1 −n f )]( a f −a s )( T d −T M ) (3)
where E f and n f are Young's modulus and Poisson ratio for said thin film, respectively, a f and a s are average thermal coefficients of said thin film and said substrate, and T d and T M are film deposition temperature and temperature during stress measurement, respectively.
19. A method of forming a DRAM cell, comprising:
providing a substrate having CMOS structures to a sample holder;
situating said sample holder in a deposition chamber;
flexing the substrate;
depositing a thin film of a barrier material on the flexed substrate; and
unflexing the substrate, wherein said flexing the substrate provide a mechanical stress s to said thin film, said mechanical stress being derived using the following equations:
s=s i +s T (1)
where s i is intrinsic stress calculated by the expression:
s i =[E s /6(1− n s )]( d s 2 /d f )(1 /R s −1 /R f ) (2)
where E s and n s are Young's modulus and Poisson ratio of said substrate, respectively, d s and d f are thickness of said substrate and said thin film, respectively, and R s and R f are radii of curvature of said substrate without and with said thin film, respectively, and where s T is thermal stress in said thin film calculated by the expression:
s T =[E f /(1 −n f )]( a f −a s )( T d −T M ) (3)
where E f and n f are Young's modulus and Poisson ratio for said thin film, respectively, a f and a s are average thermal coefficients of said thin film and said substrate, and T d and T M are film deposition temperature and temperature during stress measurement, respectively.