An exposure mask includes a first transmission portion, a second transmission portion, and a blocking portion. The first transmission portion is configured to, when illuminated with light, transmit the light at a first energy level. The first transmission portion is disposed in association with formation of a first contact hole in an underlying layer. The second transmission portion is configured to, when illuminated with the light, transmit the light at a second energy level. The second transmission portion is disposed in association with formation of a second contact hole in the underlying layer. The blocking portion is configured to block the light, and is disposed in association with a boundary region between a first region and a second region of the underlying layer. The second transmission portion is further configured to enable the second contact hole to be formed deeper into the underlying layer than the first contact hole.