Author Affiliations
1 Laboratory of Information Optics and Optoelectronic Technology, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China2 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences,Beijing 100049, Chinashow less
Fig. 1. Principle diagram of SMASH alignment technique
Fig. 2. Beam diffraction diagrams of different alignment marks. (a) Symmetric alignment mark; (b) asymmetric alignment mark
Fig. 3. Simulation model of alignment mark
Fig. 4. Asymmetric alignment marks with different shapes. (a) Round shape; (b) wedge shape
Fig. 5. Alignment measurement errors as functions of deformations of different asymmetric alignment marks under illuminations with different wavelengths and polarizations. (a) Round shape; (b) wedge shape
Fig. 6. Simulation results. (a) Ra-Rb as a function of Rb; (b) Wa-Wb as a function of Wb
Fig. 7. Alignment measurement errors caused by asymmetric alignment marks with different shapes after calibration. (a) Round shape; (b) wedge shape
Fig. 8. Principle diagrams of overlay precision measurement based on DBO technique. (a) eoverlay<0; (b) eoverlay=0; (c) eoverlay>0
Fig. 9. Overlay measurement error caused by asymmetric deformation of overlay mark
Fig. 10. Simulation model of overlay mark
Fig. 11. Overlay measurement error as a function of deformation of different asymmetric overlay marks under illuminations with different wavelengths and polarizations. (a) Round shape; (b) wedge shape
Fig. 12. Overlay measurement error as a function of alignment measurement error caused by different asymmetric deformations. (a) Round shape; (b) wedge shape
Fig. 13. Simulation results of overlay measurement errors caused by asymmetric overlay marks with different shapes after calibration. (a) Round shape; (b) wedge shape
Material | Refractive index |
---|
532 nm | 632.8 nm | 775 nm | 850 nm |
---|
Si | 4.1520+0.05179i | 3.8823+0.01959i | 3.7139+0.00799i | 3.6730+0.00500i | SiO2 | 1.4607 | 1.4570 | 1.4541 | 1.4525 |
|
Table 1. Refractive indexes with alignment mark materials under different wavelengths
Material | Refractive index |
---|
400 nm | 500 nm | 600 nm | 700 nm |
---|
Si | 5.5674+0.3860i | 4.2992+0.0704i | 3.9485+0.0274i | 3.6730+0.0122i | Copolymer resist | 1.4961 | 1.4864 | 1.4827 | 1.4809 | SiO2 | 1.4701 | 1.4623 | 1.4580 | 1.4553 |
|
Table 2. Refractive indexes of overlay mark materials under different wavelengths