Good news,
I fanally solved my problem. Since IB where busy with the Covid-19, it took me 3 weeks in total to make all arrangements and have my USD account working.
First, I took out my CAD $ from my IB account.
I've then opened a USD account over the Internet with my current Royal Bank of CANADA but it did not work. They could not make a USD transfer to a Canadian provider since it was going to convert my USD deposit to CAD and I could not link this account to IB. They had to transfer me to another department for USD account with RBC in USA.
I then checked with Bank of Montreal where I have another account ond opened a USD account. Took me 2 minutes over the Internet. I then linked my account directly with IB. After the verification, I was able to make a deposit in US to my account.
Now, everything is working perfectly, I don't loose even 1$ from my gains.
Hope this topic could help someone.