Apparatus and process for bulk wet etch with leakage protection

A process for wet etching a silicon wafer having front and back surfaces, comprising:

• providing first and second chambers that are separated from each other by said silicon wafer whereby said back surface is part of said first chamber and said front surface is part of said second chamber;
• providing seals that prevent liquid from flowing between said chambers;
• causing a solution of potassium hydroxide, at a first temperature and pressure, to flow into and out of said first chamber, in a direction parallel to said back surface through a rotating shower head, whereby turbulence is induced in said potassium hydroxide solution thereby removing from said back surface any bubbles that may form there;
• causing deionized water, at a second temperature and pressure, to flow into and out of said second chamber in a direction parallel to said front surface through a rotating shower head, whereby turbulence is induced in said deionized water thereby removing any bubbles that may form on said front surface;
• monitoring deionized water in said second chamber for the presence of potassium hydroxide;
• and
• etching said back surface for a period of time that is insufficient for said potassium hydroxide solution to etch all the way through any part of said silicon wafer.