[Tex/LaTex] Splitting a beamer page into minipages by horizontal and vertical splits, and using “pause” to display minipages one-by-one

Question

I want to split a page into 3 minipages (sections): 2 minipages in the left half of the page (by splitting the left half horizontally) and 1 minipage in the right half of the page. In each minipage, I want a figure and a footnote or text to be inserted. The MWE using the minipage environment is given below. This only shows the "Figure left top" and "Figure right." "Figure left bottom" does not appear. Also, "Figure right" is displayed on the left bottom section. I also would like to display these minipages one-by-one, by using pause which has been commented right now. Please suggest what's going wrong here, and if minipage is not the best way to achieve this. Is that because I haven't specified the positions correctly for each of the three minipages?

\begin{frame}{Title of frame}
    \begin{minipage}[t][0.45\textheight][t]{0.45\textwidth}
%       \begin{figure}
%           \includegraphics[width=\textwidth]{Figure_left_top.pdf}
%       \end{figure}
        \footnotetext{Figure left top}
    \end{minipage}
    %\pause
    \begin{minipage}[t][0.9\textheight][t]{0.45\textwidth}
%       \begin{figure}
%           \includegraphics[width=\textwidth]{Figure_right.pdf}
%       \end{figure}
        \footnotetext{Figure right}
    \end{minipage}
    %\pause
    \begin{minipage}[t][0.45\textheight][t]{0.45\textwidth}
%       \begin{figure}
%           \includegraphics[width=\textwidth]{Figure_left_bottom.pdf}
%       \end{figure}
        \footnotetext{Figure left bottom}
\end{frame}

Answer 1

Are you looking for a layout like this?

\documentclass{beamer}

\begin{document}

\begin{frame}[t]{Title of frame}
    \begin{columns}[T,onlytextwidth]
        \begin{column}{.4\textwidth}
            \begin{minipage}{\textwidth}
                \begin{figure}
                    \includegraphics[width=\textwidth]{example-image}
                \end{figure}
                \footnotetext{Figure left top}
            \end{minipage}  
            \begin{onlyenv}<3>
                \begin{minipage}{\textwidth}
                    \begin{figure}
                        \includegraphics[width=\textwidth]{example-image}
                    \end{figure}
                \footnotetext{Figure left bottom}
                \end{minipage}
            \end{onlyenv}
        \end{column}
        \begin{column}{.4\textwidth}
            \begin{onlyenv}<2->
                \begin{minipage}{\textwidth}
                    \begin{figure}
                        \includegraphics[width=\textwidth, height=.77\textheight]{example-image}
                    \end{figure}
                    \footnotetext{Figure right}
                \end{minipage}
            \end{onlyenv}
        \end{column}
    \end{columns}
\end{frame}

\end{document}