Yes, it is possible, depending on where you live and what first-time home buyer programs are available in your area. With a credit score of 620, you can qualify for FHA financing. For mortgage purposes, your credit score is the lowest middle score of both borrowers.
FHA has a minimum down payment of 3.5% of the purchase price. If you are in an area that has down payment assistance programs, you may be able to obtain 100% financing.
The last piece of the puzzle is that your income must be enough to cover the new housing payments and your current monthly debt at a debt-to-income ratio that meets loan guidelines.
Also, a program called USDA Rural Home financing is a 100% loan program. Rural does not mean the property has to be out in the boonies. Different counties and cities are eligible and then there is a link to a website where individual addresses can be checked.
Go to www.hud.gov for information on FHA financing, and http://eligibility.sc.egov.usda.gov/eligibility/welcomeAction.do, to find out about the USDA program. There is also a lot of information on my website, www.theloanlady.net.