How can I get rid of ants in my kitchen, although the area is clean?

Destroy the nest to eradicate, Keep using your trusted method.

Mix borax with some sugar water. Place in bottle caps where pets and children cannot get to. Ants are attracted to sugar and water borax kills ants. They will bring it back to the nest.

Boric acid with sugar and water is even better!

https://www.thespruce.com/how-to-get-rid-of-ants-2656468

Ants cannot digest cornmeal. Put cornmeal where you see a trail or where you see they may be coming into the house. We use Jiffy because it is sweet and they quickly are attracted to it. They take it back to the queen. If you know where a hill is, that would be easier to cover to get rid of them. Be patient and just let them have cornmeal. It will get rid of them once the colony is dead. They take it back to the queen. It is safe, inexpensive and not harmful to pets or children and it DOES work. We have used it for years.

I tried Dettol on my sponge, which worked until I stopped using Dettol. But to kill them off I eventually bought from the store a box that contains "food particles". The ants go into the box and take out the particles, these particles kill the ants in their nest. Now there are no ants!

You need to wipe the counters with vinegar to remove the trail they leave for the rest of the ants. I finally broke down and got those little plastic tabs with ant bait - some brands work better than others.

Have you tried Terro? It works like a charm. The bait traps are the best.

Always a pleasure....

Try cinnamon or corn meal in thier path

Borax and sugar trap should work: https://www.hometalk.com/diy/outdoor/pest-repeller/quick-dyi-sweet-bait-to-treat-and-get-rid-of-your-ants-18515410