No that is not possible. Only the person who created the account may use it and Steam accounts can not be given or transferred to another user.
Giving your account to someone else is actually a reason for your account to be terminated according to the Steam TOS.

What you CAN do is creating a separate account for your son in his name with him and then joining a Steam Family with both your accounts.
Then your son has full access to your games and can play them on his own account.

That may be the best solution in your case.