First off, we can remove the condition that $|A| \geq |F|^{\delta}$. One expects to be able to take any $\epsilon < 1$, as long as $|A| \leq |F|^{1/2}$. The most recent progress is [contained in this joint work with Rudnev and Shkredov][1]. It is known you cannot take $\epsilon =1$, say by work on the multiplication table problem or a slightly different construction in the original paper of Erdos and Szemeredi on the sum-product conjecture. 

  [1]: https://arxiv.org/abs/1808.08465