Patent EP-2226678-A1 (EP)
Inventor: LANDIS STEFAN
IPC: G03F7/00
Filed: 2010-03-01
Abstract: The process comprises forming a trench (6) in a silicon-on insulator substrate (2) in three types of surfaces including a base of the trench, sidewalls of the trench and top of the substrate, forming a first material and a second material that is selectively etched with respect to the first material in alternate layers of the trenches such that 4(i), where i=1, 2, 3 up to n and each having a portion perpendicular to the substrate, and selectively engraving the portions of layers perpendicular to the substrate to form a topology comprising first patterns (5) made of first material. The process comprises forming a trench (6) in a silicon-on insulator substrate (2) in three types of surfaces including a base of the trench, sidewalls of the trench and top of the substrate, forming a first material and a second material that is selectively etched with respect to the first material in alternate layers of the trenches such that 4(i), where i=1, 2, 3 up to n and each having a portion perpendicular to the substrate, and selectively engraving the portions of layers perpendicular to the substrate to form a topology comprising first patterns (5) made of first material of which the tip is at a first level with respect to a surface of the substrate located on both sides of the topology and second patterns made of second material having a second level with respect to the surface of the substrate different from first level and lower than that of the first patterns. The process further comprises engraving a part of the substrate on both sides of topology in which the first unit is then protruded with respect to the surface of the substrate, engraving the second material such that the tip of the first pattern has a level equal to that of the surface of the substrate, and performing anisotropic engraving of the first and second type of the material. The formation of alternating layers is perpendicular to the substrate and to the base of the trenches. A material limiting or inhibiting the formation of alternating layers on the bottom of the substrate is formed in the bottom of trenches. The substrate comprises a surface layer of semiconductor material, a buried insulating layer and a support. A portion of the buried insulating layer forms a layer of material limiting or inhibiting the formation of alternating layers on the bottom of the substrate and trenches, and is obtained by engraving the surface layer just up to the buried insulating layer. The material limiting or inhibiting the deposition of alternating layers is further formed on the top of the substrate, and the alternating layers are then uniformly deposited in the trenches and a thinning is carried out for exposing the side of the substrate. The trench is not entirely filled by alternating layers to leave a residual portion of the trench. A filler is deposited in a portion of residual trench. A difference of engraving speed between two layers of second patterns is obtained by difference of composition of material between the two layers. The first material is made of silicon (Si) and the second material is made of (SiGe) x, where x is greater than 15% and Ge is germanium. An independent claim is included for a device for fabricating a three dimensional impression mold.