html_writer::tag escaping moodle url

Hello, 

I have a little problem with html_writer::tag:

When i use the following 2 lines:

$target_1 = new moodle_url('/mod/multiplesurvey/view.php',array('edit'=>'true','id'=>3));
$html .= html_writer::tag('input','',array('type'=>'button','value'=>'Test Survey','onclick'=>'location.href="'.$target_1.'"'));

it always sends me to http://localhost/moodle/mod/multiplesurvey/view.php?edit=true&id=3

so it always escapes the & before the second parameter !

what do i do wrong or is this the wrong funktion in the renderer.php file ?

Thanks.