Draw a circle smaller than 0.1 using Tikz

I am trying to draw a bullet point (filled circle) with Tikz. With the following code, I can draw the circle:

documentclass{article}

usepackage{tikz}
usetikzlibrary{shapes,arrows}
begin{document}
begin{tikzpicture}

node [draw, shape = circle, fill = black, minimum size = 0.1cm] (){};

end{tikzpicture}
end{document}

I would like to draw a smaller point, but decreasing the minimum size = 0.1 cm to, say, 0.0001 cm does not make a difference. I am wondering what the cause of this behaviour is, and how to fix it?

node [draw, shape = circle, fill = black, minimum size = 0.1cm, inner sep=0pt] (){};