If your son is a full time student, you could be on the loan as a non owner occupied co-borrower. Your incoome, credit and assets could be factored into the qualifying.
You also could purchase the home as an investment property and lease it to your son and fellow students. Then you have nice asset to help you reduce your tax liability. Talk to your CPA about the joys of owning investment property.
Then no. Have him call a mortgage broker to find out what he can qualify for given his current income, qualifications and credit.