Method of determining defects in photomask
View Patent ↗A method of determining defects in photomasks according to the present invention is designed to increase the yield of the manufacture of photomasks and to decrease the cost of inspecting the photomasks. In the method, circuit data 1 representing a circuit to be formed on a semiconductor substrate by photolithography is prepared, and layout data 2 is prepared from the circuit data 1 . The layout data is converted to compensated layout data by performing RET. Further, mask-manufacturing data is developed from the compensated layout data. To form patterns on a semiconductor substrate by photolithography, attribute information is imparted to the mask-manufacturing data. The attribute information represents whether the patterns are adaptive to electrically active regions or electrically non-active region. In the mask-inspecting process 6 , a criterion for determining whether the patterns formed on the photomasks have defects is changed in accordance with the attribute information.
1. A method of determining defects in photomasks manufactured in a mask-manufacturing apparatus on the basis of mask-manufacturing data for manufacturing a plurality of masks, the method having:
a step of preparing circuit data that represents a circuit to be formed on a semiconductor substrate by means of photolithography;
a step of preparing layout data that has been developed from the circuit data and that represents the layout of a plurality of layers, which defines the circuit and which is to be formed on the semiconductor substrate, one above another;
a step of preparing compensated layout data for the layers, by adding compensation data to the layout data representing the layout of the layers; and
a step of preparing mask-manufacturing data that has been developed from the compensated layout data for the layers and that has been used to manufacture the masks for the layers,
the method further comprising:
a step of extracting patterns adaptive to active regions and non-active regions in order to form electrically active regions and electrically non-active regions when a certain pattern is formed by photolithography on the semiconductor substrate, in accordance with a connection-information table that describes a connection between circuit patterns represented by the layout data for the layers;
a step of imparting attributes to all patterns represented by the mask-manufacturing data for manufacturing masks for the layers, the attributes showing whether the patterns are adaptive to active regions or non-active region; and
a step of changing a criterion for determining whether the patterns formed on the photomasks have defects depending on whether each of the patterns correspond to an active region or a non-active region, in accordance with the attributes imparted to the patterns represented by the mask-manufacturing data for manufacturing masks for the layers.
2. The method of determining defects in photomasks according to claim 1 , wherein the connection-information table is a table that describes connection between the layers in which the patterns are provided.
3. The method of determining defects in photomasks according to claim 1 , wherein compensation is performed by optical proximity correction in the step of preparing compensated layout data for the layers.
4. The method of determining defects in photomasks according to claim 1 , wherein compensation is performed by phase shifting in the step of preparing compensated layout data for the layers.
5. The method of determining defects in photomasks according to claim 1 , wherein attributes that accord with the type of patterns adaptive to the active regions are imparted to the patterns represented by the mask-manufacturing data for manufacturing the masks for the layers.
6. The method of determining defects in photomasks according to claim 5 , wherein the type of the patterns adaptive to the active regions is determined from circuit-connection information (text data defining wires constituting a circuit and signals at terminals).
7. The method of determining defects in photomasks according to claim 5 , wherein the criterion for determining whether the patterns formed on the photomasks have defects is changed in accordance with the attributes imparted to the type of the patterns adaptive to the active regions.
8. The method of determining defects in photomasks according to claim 6 , wherein the criterion for determining whether the patterns formed on the photomasks have defects is changed in accordance with the attributes corresponding to the type of the patterns adaptive to the active regions.
9. The method of determining defects in photomasks according to any one of claim 1 to 8 , wherein attributes corresponding to the type of patterns adaptive to the non-active regions are imparted to the patterns represented by the mask-manufacturing data for manufacturing the masks for the layers.
10. The method of determining defects in photomasks according to claim 9 , wherein the criterion for determining whether the patterns formed on the photomasks have defects is changed in accordance with the attributes corresponding to the type of the patterns adaptive to the non-active regions.