A deposition mask consisting of: - a metal plate comprising a first surface and a second surface opposite to each other, and perpendicular to a direction of thickness c, o wherein said metal plate is characterized by a rectangular sample substrate having a width of 30 mm and a length of 180 mm as dimensions and etched, said sample substrate being divided into a central etched area and a non-etched area located on each sided of the central etched area except for 10 mm inwards from both ends of said sample substrate, said central etched area being etched so that its thickness corresponds to 2/3 to 1/2 of the thickness c of the sample substrate, o wherein said metal plate is obtained from a base material being submitted to a cooling process at a temperature between 10 °C and 20 °C, 10°C and 20°C, followed by a rolling process to realize the metal plate having a desired thickness corresponding to a reduction ratio comprised between 2/3 to 1/5 with respect to a volume of 1 mm 3 at a predetermined point of the base material, so that said sample substrate has a twist index (Hr) having a value between 0.2 μm and 7 pm, the twist index (Hr) satisfying equation when the sample substrate is disposed on a horizontal target surface of a surface plate: Hr = H1 − Ha 2 + H2 − Ha 2 + H3 − Ha 2 + H4 − Ha 2 1 / 2 With (Ha) being defined according to equation as the average of distances H1, H2, H3, and H4 being measured from the horizontal target surface to each of the four corners of the sample substrate expressed in micrometers: Ha = H1 + H2 + H3 + H4 / 4, and - a plurality of unit holes (110, 120) comprising first surface holes formed through the first surface and second surface holes formed through the second surface, said first surface holes and second surface holes being connected with each other through a boundary part. - a metal plate comprising a first surface and a second surface opposite to each other, and perpendicular to a direction of thickness c, o wherein said metal plate is characterized by a rectangular sample substrate having a width of 30 mm and a length of 180 mm as dimensions and etched, said sample substrate being divided into a central etched area and a non-etched area located on each sided of the central etched area except for 10 mm inwards from both ends of said sample substrate, said central etched area being etched so that its thickness corresponds to 2/3 to 1/2 of the thickness c of the sample substrate, o wherein said metal plate is obtained from a base material being submitted to a cooling process at a temperature between 10 °C and 20 °C, 10°C and 20°C, followed by a rolling process to realize the metal plate having a desired thickness corresponding to a reduction ratio comprised between 2/3 to 1/5 with respect to a volume of 1 mm 3 at a predetermined point of the base material, so that said sample substrate has a twist index (Hr) having a value between 0.2 μm and 7 pm, the twist index (Hr) satisfying equation when the sample substrate is disposed on a horizontal target surface of a surface plate: Hr = H1 − Ha 2 + H2 − Ha 2 + H3 − Ha 2 + H4 − Ha 2 1 / 2 With (Ha) being defined according to equation as the average of distances H1, H2, H3, and H4 being measured from the horizontal target surface to each of the four corners of the sample substrate expressed in micrometers: Ha = H1 + H2 + H3 + H4 / 4, and o wherein said metal plate is characterized by a rectangular sample substrate having a width of 30 mm and a length of 180 mm as dimensions and etched, said sample substrate being divided into a central etched area and a non-etched area located on each sided of the central etched area except for 10 mm inwards from both ends of said sample substrate, said central etched area being etched so that its thickness corresponds to 2/3 to 1/2 of the thickness c of the sample substrate, said sample substrate being divided into a central etched area and a non-etched area located on each sided of the central etched area except for 10 mm inwards from both ends of said sample substrate, said central etched area being etched so that its thickness corresponds to 2/3 to 1/2 of the thickness c of the sample substrate, o wherein said metal plate is obtained from a base material being submitted to a cooling process at a temperature between 10 °C and 20 °C, 10°C and 20°C, followed by a rolling process to realize the metal plate having a desired thickness corresponding to a reduction ratio comprised between 2/3 to 1/5 with respect to a volume of 1 mm 3 at a predetermined point of the base material, so that said sample substrate has a twist index (Hr) having a value between 0.2 μm and 7 pm, the twist index (Hr) satisfying equation when the sample substrate is disposed on a horizontal target surface of a surface plate: Hr = H1 − Ha 2 + H2 − Ha 2 + H3 − Ha 2 + H4 − Ha 2 1 / 2 With (Ha) being defined according to equation as the average of distances H1, H2, H3, and H4 being measured from the horizontal target surface to each of the four corners of the sample substrate expressed in micrometers: Ha = H1 + H2 + H3 + H4 / 4, and - a plurality of unit holes (110, 120) comprising first surface holes formed through the first surface and second surface holes formed through the second surface, said first surface holes and second surface holes being connected with each other through a boundary part.