1. Field of the Invention
The present invention relates to a processing probe for performing a minute process using a probe microscope technique and, more particularly, to a processing probe used in a method of removing a defective portion by mechanical scratching during repair of a photo-mask defect.
2. Background Art
As is generally known, when a photo-mask causes a defect of a transferred pattern, repair is required after inspection since the photo-mask is used as an original. There are two kinds of repair methods: black defect (convex defect) repair method in which a redundant shielding film is removed; and white defect repair method in which a shielding film is formed at a portion lacking pattern. In the white defect repair method, a general method is to spray organic gas on a surface of the mask while a gallium ion is radiated to deposit a carbon film (FIB deposition: Focused Ion Beam System). On the other hand, as the black defect repair method, there is known a laser repair method in which a laser beam is radiated on a defective portion to vaporize a remaining portion of the shielding film in an instant, and an FIB gas assist etching method in which a gallium ion is radiated to carry out sputtering. In the laser repair method, the processing shape, reduction of damage to glass substrate and reduction of rise of an edge are improved while improvement in optical resolution and precision of image processing and a sample stage are achieved so as to be able to correspond to a minute pattern. It is difficult, however, to completely correspond to a further minute pattern due to an optical limit, so that the FIB repair method is the mainstream of the minute pattern repair. In the FIB repair method a superior height controlling characteristic is required due to a shortening of an exposure wavelength, and over-etching and re-adherence deteriorate an optical characteristic. Further, there is also a problem that end point detection is incorrectly performed in the case of using a halftone mask or a Levenson mask.
In view of the above, there is a scratching process, which is superior in height controlling characteristic in the black defect removing and has an advantage that the end point detection goes well even in the case of using a halftone mask or a Levenson mask. In the scratching process, a probe harder than a material to be processed is used for physical removal. As the scratching process, there has been proposed a minute processing method in which a probe is used with the probe microscope technique (refer to Non-Patent Reference 1, for example). It has been known that the probe microscope is an apparatus in which physical force such as atomic force operated between a sample and a minute probe produced with a micro-machine technique is detected as change in shape or displacement of the minute probe so that a shape and a physical characteristic of a surface of the sample would be converted into an image to observe and measure the image (refer to Non-Patent Reference 2, for example).
Non-Patent Reference 1 discloses a mechanical scratch of a defective portion of a photo-mask by means of a probe with the above-mentioned technique used for the probe microscope (the probe microscope technique).
FIG. 5 shows an example of repairing a photo-mask defect by means of a probe. FIG. 5a is a simplified perspective view of a defective potion of a photo-mask, which is a target of the probe process. FIG. 5b illustrates the defective portion shown in FIG. 5a, which is under processing by means of a probe.
In FIG. 5a, 20 denotes a glass substrate of a photo-mask. A mask pattern film 21 (a chrome film, for example) formed on the glass substrate of a photo-mask 20 has a redundant convex defect 22. A defect target for repairing by probe processing is thus a black defect shown by the numeral 22. The defect 22 is removed by moving a probe 24 formed on a top end of a member usually called a cantilever 23, which is formed in the shape of a strip as shown in FIG. 5b, as shown by an arrow 25.
A probe used in the probe microscope technique is mainly formed by anisotropically etching silicon. Accordingly, a probe used in a method of minute processing by means of a probe is usually formed from silicon, and thereby, is an insulating material. Further, there has also been a probe provided such that a cantilever member formed in the shape of a strip is formed with the micro-machining technique or from a metal thin film and diamond or the like is adhered thereto so as to produce a probe (refer to Non-Patent Reference 3, for example) Such a probe is also made from an insulating material. In the case that a material of the probe is insulative, a mask pattern is likely to be damaged because of electric discharge between the mask patterns caused by static electricity due to friction in a method of removing the defective portion by scratching with a probe since a material of the photo-mask is glass.
[Non-Patent Reference 1] Proceedings of SPIE Vol. 5256 [Photo-mask repair performance of the SiON/Ta—Hf attenuating PSM] Masaharu Nishiguchi, Tauyoshi Amano, Shiho Sasaki, Yasutake Morikawa, and Naoya Hayashi (FIG. 2, Bottom in Page 1201, Lines 1 to 7 in Page 1202)
[Non-Patent Reference 2] [Scanning Type of Probe Microscope, Foundation And Future Forecast] Edited and written by Seizo Morita, Maruzen, Feb. 10, 2000 (Line 7 in Page 21 to Line 12 in Page 24)
[Non-Patent Reference 3] Journal of the Japan Society for Abrasive Technology [Development of Atomic Force Microscope Integrated Type of Processing Evaluation Apparatus—Development of AFM Cantilever for Processing] Vo. 41, No. 7, July 1997. 276-281 (Line 17 in Left Column in Page 277 to Line 19 in Left Column in Page 279) Kiwamu Ashida, Noboru Morita, Kitaro Yoshida, Seiji Hirai