I need the following with \onslide

I have used the following Latex code
$\onslide<1->{\left[}\onslide<2->{\dfrac{e^{-st}}{s^2+1}}\onslide<3->{\left(-s\sin t - \cos t\right)}\onslide<4->{\right]_0^{\pi}}$
and its output is as follows

I need the following with \onslide

I have used the following Latex code
$\onslide<1->{\left[}\onslide<2->{\dfrac{e^{-st}}{s^2+1}}\onslide<3->{\left(-s\sin t - \cos t\right)}\onslide<4->{\right]_0^{\pi}}$
and its output is as follows

Simply use fixed size parenthesis:
\documentclass{beamer}
\begin{document}
\begin{frame}
$
\onslide+<1->{\bigg[}\onslide+<2->{\dfrac{e^{-st}}{s^2+1}}\onslide+<3->{\left(-s\sin t - \cos t\right)}\onslide+<4->{\bigg]_0^{\pi}}
$
\end{frame}
\end{document}