show popup window minimized

var win;

    function openWindow() {
        if (win == null || win.closed == true) {
            win = window.open('Help.htm', 'Help', 'top=150,left=200,width=450,height=250,resizable=yes,scrollbars=yes');
            win.focus();
            return false;
        } else {
            win.target = "Help.htm";
            win.focus();
            return false;
        }
    }

How to call

OnClientClick="javascript:return openWindow();"