Abstract: A thin film transistor (100) is mounted on a substrate (102), which is covered by a semiconductor layer (120). The semiconductor layer (120) has a first doped region (121) and a second doped region (122) with an undoped region (123) in between. In addition, the semiconductor layer (120) has a first further doped region (125) and a second further doped region (126) forming the source and drain of the thin film transistor (100) and being more heavily doped than the first doped region (121) and the second doped region (122). A part of the semiconductor layer (120) is covered by an oxide layer (140), which carries a conductive gate (104) over the undoped region (130) and a first spacer (111) and second spacer (112) over the first doped region (121) and the second doped region (122) respectively.

Abstract: A method of producing a top gate thin-film transistor in which an insulated gate structure (14) is formed over an amorphous silicon layer with upper gate conductor (16) directly over the gate insulator layers. The gate conductor is patterned to be narrower than a spacing to be provided between source and drain electrode contacts. Laser annealing of areas of the amorphous silicon layer (12) not shielded by the gate conductor (16) is carried out to form polysilicon portions. The gate insulator layers are formed as a gate insulator layer (14a, 14b) of first refractive index, and an overlying surface insulator layer (14c) of second, lower, refractive index. The overlying surface insulator layer has been found to reduce fluctuations in the reflectance of the structure in dependence upon the specific thicknesses of the gate insulator layers. Therefore, the tolerances for the thicknesses of the gate insulator layers can be reduced whilst maintaining control of the laser annealing process.

Abstract: A method of producing a top gate thin-film transistor in which an insulated gate structure (14) is formed over an amorphous silicon layer with upper gate conductor (16) directly over the gate insulator layers. The gate conductor is patterned to be narrower than a spacing to be provided between source and drain electrode contacts. Laser annealing of areas of the amorphous silicon layer (12) not shielded by the gate conductor (16) is carried out to form polysilicon portions. The gate insulator layers are formed as a gate insulator layer (14a,14b) of first refractive index, and an overlying surface insulator layer (14c) of second, lower, refractive index. The overlying surface insulator layer has been found to reduce fluctuations in the reflectance of the structure in dependence upon the specific thicknesses of the gate insulator layers. Therefore, the tolerances for the thicknesses of the gate insulator layers can be reduced whilst maintaining control of the laser annealing process.

Abstract: A method of producing a top gate thin-film transistor in which an insulated gate structure (14) is formed over an amorphous silicon layer with upper gate conductor (16) directly over the gate insulator layers. The gate conductor is patterned to be narrower than a spacing to be provided between source and drain electrode contacts. Laser annealing of areas of the amorphous silicon layer (12) not shielded by the gate conductor (16) is carried out to form polysilicon portions. The gate insulator layers are formed as a gate insulator layer (14a,14b) of first refractive index, and an overlying surface insulator layer (14c) of second, lower, refractive index. The overlying surface insulator layer has been found to reduce fluctuations in the reflectance of the structure in dependence upon the specific thicknesses of the gate insulator layers. Therefore, the tolerances for the thicknesses of the gate insulator layers can be reduced whilst maintaining control of the laser annealing process.

Abstract: An ion implantation process comprises performing mass separation of ions from an ionised source of phosphorus so as to select the P2 ions and reject phosphorus hydride ion species. The P2 ions are injected into a semiconductor substrate. The rejection of phosphorus hydride ions species is facilitated because there are no such species adjacent (in terms of effective mass) the P2 ion species. The use of the P2 ion species also improves the implantation process for shallow implantation depths.

Abstract: An image sensor comprises switching elements 30 on a substrate 1. An insulating separation layer 9 is disposed over the switching elements so that a photodiode arrangement 20a disposed over the insulating separation layer 9, can overlap the switching elements 30 and occupy a maximum area of the image sensor. A barrier layer 10 is interposed between the insulating separation layer 9 and the photodiode arrangement 20a, which prevents degradation of the photodiode characteristics over time.