POLISHING STOP LAYER(S) FOR PROCESSING ARRAYS OF SEMICONDUCTOR ELEMENTS

摘要

Described embodiments can be used in semiconductor manufacturing and employ materials with high and low polish rates to help determine a precise polish end point that is consistent throughout a wafer and that can cease polishing prior to damaging semiconductor elements. The height of the low polish rate material between the semiconductor elements is used as the polishing endpoint. Because the low polish rate material slows down the polishing process, it is easy to determine an end point and avoid damage to the semiconductor elements. An additional or alternative etch end point can be a thin layer of material that provides a very clear spectroscopy signal when it has been exposed, allowing the etch process to cease.

主权项

1. A method manufacturing a semiconductor device comprising:
fabricating a plurality of magnetic tunnel junction (MTJ) pillars on a wafer, each of the plurality of MTJ pillars having a top surface and a side surface, the top surface extending at an MTJ pillar height from the wafer; depositing a first layer on the semiconductor wafer, the first layer being comprised of a high chemical-mechanical polish (CMP) rate material, such that the first layer covers the top surface and side surface of each of the plurality of MTJ pillars, the first layer forming a first layer bump portion over the top surface of each of the plurality of MTJ pillars and a first layer side surface portion over the side surface of each of the plurality of MTJ pillars and a plurality of first layer valley portions in between the plurality of MTJ pillars; depositing a second layer over the first layer, the second layer being comprised of a low CMP rate material, such that a second layer bump portion covers the first layer bump portion, a second layer side portion covers the first layer side portion, and a plurality of second layer valley portions cover the plurality of first layer valley portions, thereby forming a plurality of MTJ pillar bumps, each of the plurality of MTJ pillar bumps corresponding to the top surface of each of the plurality of MTJ pillars, the second layer having a thickness selected such that a top surface of the plurality of second layer valley portions are at a CMP stop height; chemical-mechanical polishing the plurality of MTJ pillar bumps with a chemical-mechanical polisher; detecting that the chemical-mechanical polisher has reached the top surface of second layer valley portion; and stopping the chemical-mechanical polishing step when the polisher has reached the top surface of the plurality of second layer valley portions such that the side surface of each of the plurality of MTJ pillars remains covered by the first layer and the second layer.