How Can I Use Equal And Question Mark In Category Slug?

I need to add a question mark and equal the category url.

I need this: site.com/stack?exchange=ask

But Wordpress does not allow specific characters in url. So i tried to use html encodes in category slug. Like as site.com/stack%3Fexchange%3Dask

Thus, the url shown with html encodes and this category does not list the products.

How can i use ? and = in the category slug?

Regards