Abstract: Novel high purity dimethylaluminium chloride compositions are provided that are suitable for semiconductor applications, such as atomic layer etch and aluminum ion implantation. The reduction or minimization of specified gaseous impurities allows the vapor phase of the DMAC to have purity levels of 99.9 mol % or higher to selectively etch various atomic layers with high selectivity and high etch precision at acceptable etch rates and 99 mol % or higher to ion implant aluminum ions without substantial implantation of C2H3 ions into a wafer device, thereby avoiding degradation or failure of the wafer device. Storage conditions are established that are conducive to maintaining the high purity levels required for such semiconductor applications.