GameObject jitter using transform.LookAt

I've got a gameObject (health bar) that's childed to a space ship that moves quite rapidly, causing a slight jitter occasionally because the gameObjects transform and scale are constantly being updated in FixedUpdate.

I know the solution has something to do with Quaternions and interpolation, but I don't quite know how to implement it into my code.

Here is the script I'm using.
GameObject jitter using transform.LookAt