Adobe CC- ACU has an Adobe Creative Cloud license that allows users to downlaod Adobe software at no cost. Below are a few that are recommended for research posters.
Adobe Comp - This mobile app is a great place to start. It allows you to create a poster layout from your mobile device using gestures, and can integrate into Photoshop, InDesign, Illustrator or Lightroom to complete your poster.
Adobe InDesign is the desktop software that is recommended for making poster presentations. It allows for customization of size, layout and design to suit your needs. Here's a good video about creating your poster in InDesign.
If you prefer Microsoft, Powerpoint is a common option for research posters. The University of Washington has some good tips for creating a poster in Powerpoint.
For Mac users, Pages is a good tool for creating research posters. It is designed for print work, and customizable for posters.