Is necessary to close a file when you only want create it? I'm supposed that it's only necessary in case of reading or writing.
_, err := os.OpenFile(name, os.O_CREATE, 0640)
Will it work? Yes. The file will be created.
Should you do it? No. It is a bad idea in general even though you can get away with it sometimes.
Opening a file allocates resources like a file handle to your process. You should close it to free those resources. Otherwise they will be unavailable until the process dies.
When you create the file you also open it, so you should close it.