Electronic devices having semiconductor memory units and method for fabricating the same

A method for forming a mask pattern, comprising:

• forming a first photoresist layer on an etch target layer over a substrate;
• forming first photoresist patterns in the first photoresist layer by exposing selected regions of the first photoresist layer to light and developing the first photoresist layer after the exposure;
• forming a second photoresist layer over the first photoresist patterns and the etch target layer;
• forming second photoresist patterns in the second photoresist layer by exposing selected regions of the second photoresist layer to light and developing the second photoresist layer after the exposure;
• and
• etching the etch target layer using a mask pattern collectively formed by the first and second photoresist patterns as an etch barrier to form hole patterns including first hole patterns and second hole patterns which define respective regions for forming separate contact holes, wherein the first hole patterns define a region for a contact hole connecting a variable resistance element with a substrate and the second hole patterns define a region for a contact hole connecting the substrate with a conductive line.

A method for fabricating an electronic device comprising:

• simultaneously forming a first and second contact holes on a substrate by using a mask;
• forming a variable resistance element to be coupled to the substrate through the first contact hole;
• simultaneously forming a third and fourth contact holes by using the mask, wherein the third contact hole is coupled to the variable resistance element and the fourth contact hole is electrically coupled to the substrate through the second contact hole;
• forming a first and second conductive lines that contact with the third and fourth contact holes, respectively.

A method for forming a mask pattern, comprising:

• forming a first photoresist layer on an etch target layer over a substrate;
• forming first photoresist patterns in the first photoresist layer by exposing selected regions of the first photoresist layer to light and developing the first photoresist layer after the exposure;
• forming a second photoresist layer over the first photoresist patterns and the etch target layer;
• forming second photoresist patterns in the second photoresist layer by exposing selected regions of the second photoresist layer to light and developing the second photoresist layer after the exposure;
• and
• etching the etch target layer using a mask pattern collectively formed by the first and second photoresist patterns as an etch barrier to form hole patterns including first hole patterns and second hole patterns which define respective regions for forming separate contact holes, wherein the non-exposed region of the second photoresist layer is inclined with respect to first photoresist patterns to form an overlapping portion with the first photoresist patterns and the overlapping portions are not located in the same line in the transverse direction.

A method for forming a mask pattern, comprising:

• forming a first photoresist layer on an etch target layer over a substrate;
• forming first photoresist patterns in the first photoresist layer by exposing selected regions of the first photoresist layer to light and developing the first photoresist layer after the exposure;
• forming a second photoresist layer over the first photoresist patterns and the etch target layer;
• forming second photoresist patterns in the second photoresist layer by exposing selected regions of the second photoresist layer to light and developing the second photoresist layer after the exposure;
• and
• etching the etch target layer using a mask pattern collectively formed by the first and second photoresist patterns as an etch barrier to form hole patterns including first hole patterns and second hole patterns which define respective regions for forming separate contact holes, wherein the non-exposed region of the second photoresist layer is inclined with respect to first photoresist patterns to form an overlapping portion with the first photoresist patterns and the overlapping portions are not located in the same line in the transverse direction.