Focused ion beam visual endpointing

A method for detecting an endpoint of an etch, the method comprising:

• etching a backside of a semiconductor chip with a focused ion beam, the semiconductor chip having a frontside including an n-well and a p-well proximate the n-well, the n-well defining an n-well junction and the p-well defining a p-well junction;
• observing the backside of the semiconductor chip during etching;
• and
• determining when a portion of the backside over the n-well differs from a portion of the backside over the p-well.

A method for etch endpoint detection, the method comprising:

• etching a backside of a semiconductor chip, the semiconductor chip having at least one doped well formed proximate a frontside of the semiconductor chip;
• monitoring the backside of the semiconductor chip during etching until at least one doped well becomes visible;
• and
• stopping etching after the doped well becoming visible.

A method for detecting an endpoint of an etch, the method comprising:

• etching a backside of a semiconductor chip with a negatively charged beam, the semiconductor chip having a frontside including an n-well and a p-well proximate the n-well, the n-well defining an n-well junction and the p-well defining a p-well junction;
• monitoring the backside of the semiconductor chip during etching;
• and
• determining when a first portion of the backside over the n-well differs from a second portion of the backside over the p-well.

An article comprising a machine-readable medium that stores machine-executable instructions for detecting an endpoint of an etch, the instructions causing a machine to:

• etch the backside of the semiconductor chip, the frontside including a first well with a first type of doping and a second well with a second type of doping;
• monitor the backside of the semiconductor chip during etching;
• and
• determine when a first portion of the backside over one of the first and second wells differs from a second portion of the backside over the other of the first and second wells.