As I said in the introduction, you can only hire people that apply for the job. Most managers will go to HR to create a job posting and wait for the resumes to come in. But I suggest you also act as your own recruiter. To be clear I am not suggesting you bypass the HR or 3rd party recruiters. Those professionals know what they are doing and in my experience, they do it very well. But there is a segment that they miss. The people that can be sold on your position by speaking with the hiring manager directly. (Engineers are in sales too, remember)
Part B of finding the right people will question who you want to interview and challenge you to expand your search criteria intentionally.
I developed an approach to finding people we might be interested in by searching LinkedIn and asking people to apply to the position. It takes some time and commitment to do it correctly but I have found it to be successful. The last time I had a position to fill, I spent about 4 hours total and was able to get 8 people that would not have applied. They either were not looking or not looking for a job at my company. Of those 8, 6 were very good interviews, and 3 were in the top 5 in our rankings. We hired one for the position and a few months later had another open position and hired one of the others. There were also 3 that were hired by other companies before we could arrange the interview.
So without any more rambling, the Process.
LinkedIn has a lot of really great search functionality built in, even without buying the little gold square. You can narrow down on the kind of experience, education, location, and quite a few other factors.
Step 1: Develop the search criteria that gives me the results I am looking for .Some trial and error is necessary. Start with geography and education, then look at keywords or possibly companies till you start seeing profiles you like.
Step 2: You will get a lot of results, like several thousand if you have the criteria correct. I just scan the profile previews LinkedIn gives you. If someone looks interesting, right click and open their profile in a new tab and keep scanning.
Step 3: Once I get a bunch of new tabs open, I will read the profile in detail to see if I want to talk to that person. The vast majority I close without contacting and go back to scanning.
Step 4: Send a connection request with a message short message. The wording is very important, it took me some trial and error to get a message that has a good response rate. Below is sample text of a message I have sent. I have bolded what I think are key to getting a response. Feel free to copy and adapt for you own use.