Patent Number: 
Section: claims

1. A thin specimen producing method comprising the steps of:acquiring a work amount of a specimen in a one-line scan by a charged particle beam of a charged particle beam apparatus;measuring a remaining work width of the specimen by a microscopic length-measuring function of the charged particle beam apparatus;determining a required number of scan lines to reach a predetermined width by calculation; andexecuting a work to obtain a set thickness. 2. A thin specimen producing method according to claim 1, wherein the work amount of a specimen in one-line scan is obtained by working the specimen by scanning plural lines of the specimen, measuring a remaining work width of the specimen by a microscopic length-measuring function of the charged particle beam apparatus, and calculating an average work amount per one-line scan. 3. A thin specimen producing method according to claim 1, wherein the microscopic length measurement executes, utilizing a microscope image by the charged particle beam or a monitoring microscope image, a pattern matching based on a drift correcting mark provided on a specimen surface, thereby measuring a specimen thickness of a finished surface in a designated part of the thin specimen. 4. A thin specimen producing method according to claim 1, wherein a specimen thickness of a finished surface of the thin specimen is confirmed by a signal of electrons reflected or transmitted by a thin film under an electron beam irradiation, or of electron-induced X-rays. 5. A thin specimen producing apparatus comprising:means for memorizing a thinning amount of a specimen in a one-line scan by a charged particle beam apparatus;means for acquiring a microscope image of an upper surface of the specimen thereby automatically measuring a remaining width of the specimen in a thinning process;means for calculating a required number of scan lines to reach a predetermined width based on the thinning amount per line and the remaining width of the specimen; andmeans for executing the required number of scans by the charged particle beam apparatus. 6. A thin specimen producing apparatus according to claim 5, further comprising an electron microscope apparatus functioning asynchronously with the charged particle beam apparatus, wherein a SEM image or a reflected electron image is sued as the microscope image. 7. A thin specimen producing apparatus according to claim 5, further comprising electron beam irradiating means and means for detecting a signal of reflected or transmitted electrons or of electron-induced X-rays, the working thickness being confirmed by the detection signal.