s1 visa process ? from shenzhen, need to get invitation letter from shenzhen immigration or not.

hey guys need your kind assistance, i'm pakistani national holding chinese Z type with teacher's experts certificate from shenzhen. i wanted to invite my wife on S1 type. My question is, do i need to get invitation letter form shenzhen immigration first?? or My wife go to chinese embassy and apply there directly with supporting documents 1- marriage certificate 2- police clearness certificate 3- medical 4- my permission letter on my company letter head 5- company's permission letter with original stamp 6- company license 7- my Z type, passport , and expert certificates copies
note: my wife is in pakistan now and i have recently got married