DRAM with asymmetrical channel doping

摘要

A method for fabricating a bit line junction in a DRAM array device which improves the doping profile in the channel region. The method includes contradoping via ion implantation through the bit line contact opening (375) made in the device during processing. This particular doping method increases the concentration of dopants in the channel region (258) on the bit line side (251) of the array, without a corresponding increase of dopants on the buried strap side (252). Such a doping profile results in an improvement in the off current behavior of the device. Depending on the aspect ratio of the contact opening, tilt angles for the ion implantation are possible and can be adjusted for maximum off current efficiency.