In order to achieve some special functions, high topography is often introduced in the manufacturing process of chip, which will directly lead to the sharp change of critical dimension (CD), especially for the implant layers post poly process. In this paper, a scheme of reducing the CD range of implant level lithography is proposed. The numerical simulation is carried out through using Fourier optics theory, Fraunhofer diffraction formula and Abbe principle，then the experiment is designed. The simulation results indicate that for advanced process, such as 110nm and 130nm generation, the normalized image logarithmic slope (NILS) of aerial image in the resist on the wafer can be maximized by appropriately increasing numerical aperture (NA) as well as decreasing σ, then the inter-field critical dimension uniformity (CDU) can be greatly improved. The experimental results show that the CD range can be decreased about 41% for the topography of 3000Å, and the better improvement can be achieved for the topography of 1600Å, up to 50%. The research results of this paper provide potential guiding significance for CDU control in implant level lithography process with high topography.
In this paper, a novel fiber Bragg grating (FBG) sensor which can measure the temperature and strain simultaneously is presented. The cladding layer of the proposed FBG sensor is made of a uniaxial crystal material (LiTaO3) and the electric field is applied on the 1/2 area of the sensor. The sensing performance was investigated by the coupled-mode theory and dual-wavelength method. We found that the strain sensitivity and the temperature sensitivity of the 1/2 area with no electric field are 0.841 pm/με and 14.31 pm/°C respectively. If the electric field is increased from 0 to 400×107 v/m, the temperature sensitivity of this device varies from 14.31 pm/°C to 14.12 pm/°C and its strain sensitivity varies from 0.841 pm/με to 0.850 pm/με. So, the obtained results demonstrate that the simultaneous measurement of temperature and strain can be achieved by using this scheme. The proposed sensor has potential applications in optical fiber sensing systems due to small size, high sensitivity and compatible with optical fiber.