Atomic layer deposition of metal phosphates and lithium silicates

An atomic layer deposition (ALD) process for forming a metal phosphate thin film on a substrate in a reaction chamber, wherein the metal phosphate comprises Ti, Al or Li, the process comprising a plurality of metal phosphate deposition cycles, each cycle comprising:

• providing a pulse of a first vapor phase metal reactant comprising Ti, Al or Li into the reaction chamber to form no more than about a single molecular layer of the reactant on the substrate;
• removing excess first reactant from the reaction chamber;
• providing a pulse of a second vapor phase phosphate reactant to the reaction chamber such that the second vapor phase reactant reacts with the first reactant on the substrate to form a metal phosphate thin film, wherein the second vapor phase phosphate reactant does not comprise a —OH group;
• and
• removing excess second reactant and reaction byproducts, if any, from the reaction chamber, and
• wherein the metal reactant and the phosphate reactant are the only reactants provided in each deposition cycle, and
• wherein each deposition cycle is free of plasma reactants.