108 results about "Cyclotron resonance" patented technology

We have discovered a method of improving step coverage of a copper seed layer deposited over a semiconductor feature surface which is particularly useful for small size features having a high aspect ratio. Using a contact via as an example of a high aspect ratio feature, we have demonstrated that despite previously-held views, it is possible to increase the copper seed layer coverage simultaneously at the bottom of the via and on the wall of the via by increasing the percentage of the depositing copper species which are ions. The percentage of species ionization which is necessary to obtain sufficient step coverage for the copper seed layer is a function of the aspect ratio of the feature. For features having a 0.25 mum or smaller feature size, an aspect ratio of about 3:1 requires that about 50% or more of the copper species be ions at the time of deposition on the substrate. As the aspect ratio increases to about 4:1, the percentage of species which are ions is preferably increased to between about 60% and 70%. When the aspect ratio is about 5:1 or greater, the percentage of species which are ions is preferably increased to greater than 80%. This increase in the percentage of copper species which are ionized can be achieved using techniques known in the art, such as, for example, laser ablation of the copper target, electron cyclotron resonance, hollow cathode, and applicants' preferred technique, an inductively coupled RF ion metal plasma. We have further discovered that when an inductively coupled plasma is used to increase ionization, an increase in power to the ionization source is not enough to obtain the desired percentage of ions in many cases. It is also necessary to increase the plasma gas pressure. Typically the plasma gas is argon, and the argon pressure in the copper seed layer deposition chamber is increased to fall within the range of about 20 to about 100 mT, preferably between about 30 mT and 70 mT.