can we apply class to checkbox input instedad of container div in cakephp

Here the code for checkbox generation

//code
echo $this->Form->select('Model.field', $options, array(
                                'multiple' => 'checkbox','div'=>'col-md-9',
                                'class' => 'required'
                            ));


//output
<div class="required" aria-required="true">
    <input type="checkbox" id="FormData6783" value="83" name="data[Model][field][]">
<label for="FormData6783">Sr. Secondary</label>
</div>
<div class="required" aria-required="true">
    <input type="checkbox" id="FormData6783" value="83" name="data[Model][field][]">
<label for="FormData6783">Secondary</label>
</div>

it applies class to container div instead of input.. Is there any way to apply class to input ?