Process step reduction at negative tone spacer patterning technique using developer soluble bottom ARC

While spacer is essential to separate the second lines from the first lines at negative tone spacer patterning technique, Spacer brings side effects such as increase in process step as well as CD budget induced by spacer. To eliminate these side effects, we have chosen the combination of photo resist as the first lines and developer soluble bottom ARC as the second lines at negative tone spacer patterning technique. This process scheme consists of only two mask steps; one is critical mask for the first lines in cell and peripheral cell, and another is non-critical mask for recess of the second lines in cell area and removal of the second lines in peripheral area. By the diffusion of acid from photo resist into developer soluble bottom ARC, developer soluble bottom ARC adjacent to photo resist of the first line is transformed into the substance, which can be easily removed by developer dispensed after the second mask exposure. With the adoption of developer soluble bottom ARC, we can expect to make progress in cost reduction at negative tone spacer patterning technique.