A minimum cash down payment from your own resources is required because mortgage lenders won't advance the entire purchase price of a property. Your minimum down payment would normally be 10%, however, a recent government program has lowered the minimum to 5% for qualified first time buyers. Another temporary program allows first time buyers to use funds from their RRSP for their down payment.
It's to your advantage to aim for a down payment of 25% or more, so you'll qualify for a conventional mortgage and avoid paying the mortgage insurance premium. The larger your down payment, the easier it will be to arrange a mortgage and carry it comfortably. The smaller your loan, the lower your interest expense will be, and the more equity you will have in your home. Equity is equal to the value of your home minus the amount of your mortgage.