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  Method of manufacturing the multi-tip probe, a multi-tip probe, and surface characteristic analysis apparatusUSPTO Application #: 20060011467Title: Method of manufacturing the multi-tip probe, a multi-tip probe, and surface characteristic analysis apparatus Abstract: In order to establish processing techniques capable of making multi-tip probes with sub-micron intervals and provide such microscopic multi-tip probes, there is provided an outermost surface analysis apparatus for semiconductor devices etc. provided with a function for enabling positioning to be performed in such a manner that there is no influence on measurement in electrical measurements at an extremely small region using this microscopic multi-tip probe, and there are provided the steps of making a cantilever 1 formed with a plurality of electrodes 3 using lithographic techniques, and forming microscopic electrodes 6 minute in pitch by sputtering or gas-assisted etching a distal end of the cantilever 1 using a focused charged particle beam or using CVD. (end of abstract) Agent: Bruce L. Adams, Esq. - New York, NY, US Inventors: Yoshiharu Shirakawabe, Hiroshi Takahashi, Tadashi Arai USPTO Applicaton #: 20060011467 - Class: 204192110 (USPTO) Related Patent Categories: Chemistry: Electrical And Wave Energy, Non-distilling Bottoms Treatment, Coating, Forming Or Etching By Sputtering, Ion Beam Sputter Deposition The Patent Description & Claims data below is from USPTO Patent Application 20060011467. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a scanning probe microscope according to the four-tip probe method which the microscope is to be used in, for example, semiconductor process evaluation, and also to a probe suitable for analyzing an ultra-surface region of a sample when used in the scanning probe microscope. [0002] 2. Description of Related Art [0003] The invention of the transistor evolved from studies on the electrical characteristics of a semiconductor surface, particularly the surface electron state. However, with regards to electrical conduction due to the state of surface electrons themselves, many points have been left unanalyzed until today. This "surface state conduction" is extremely difficult to measure because electricity runs only in one or two electron layers of a crystal surface. However, thanks to the development of new measuring and inspecting techniques such as a four-tip probe scanning tunnel microscope operating in an ultra-high vacuum and a microscopic four-tip probe, direct measurement of the surface state conduction has become possible and very interesting conduction characteristics have begun to become revealed as a result. To this end, it has evolved that the electron state of a semiconductor surface has a unique characteristic totally different from that of the bulk state. In the electron device field, apparatuses of this type will play an important role in research and development of electron devices. [0004] In an evaluating apparatus using a scanning tunnel microscope according to the four-tip probe method, four probe tips are arranged linearly at regular distances, a current is caused to flow into a sample from the outer two of the probe tips, and a voltage drop caused due to the electrical resistance of the sample is measured by the inner two of the probe tips. At that time, because there is only a very slight current flowing in these probe tips, only a voltage drop V on the sample can be measured without receiving any influence of the contact resistance at a point of contact of the probe tips with the sample. An electrical resistance according to the four-tip probe method is obtained by R=V/I where I is a measured current. As shown in FIG. 10, there is a correlation between the inter-probe-tip distance and the depth of probing into a sample. In order to obtain information of the ultra-surface of the sample, it is essential to arrange the probes at the corresponding narrow distances as shown in FIG. 10B. In the related art, however, there is a limit in processing. This is to say that the diameter of the individual probe tip served as a restriction so that a probe having a probe-tip pitch of several .mu.m could not be manufactured. [0005] Conventionally, four-tip probes whose inter-tip distance is in the order of millimeters to centimeters have been used, and many studies on this type of probe were carried out. However, these conventional probes cannot be applied to surface analysis of semiconductor devices. Recently, an undergraduate research group of Tokyo University released a report (Applied Physics, 70th Volume, 10th Issue, 2001) on measurement of electrical resistance of silicon crystal surfaces using a microscopic four-tip probe of a several .mu.m pitch manufactured utilizing silicon micro-processing technology, such as ordinary lithography. For analyzing the outermost device-surface, however, this several .mu.m inter-tip distance is inadequate to achieve proper performance. An inter-tip distance of at most 1 .mu.m or less is needed for doing so. Even if the above-mentioned silicon micro-processing technology is employed, it is difficult to manufacture a four-tip probe having an inter-tip distance of such a sub-micron order. [0006] In a further related art, positioning of measuring points on an object surface is carried out using an optical microscope. However, because a required measuring region for analyzing the outermost device-surfaces is extremely small, it is difficult to achieve positioning on the conventional optical microscope and, as an alternative means, a new observation technique, such as a scanning electron microscope (SEM) and an atomic force microscope (AFM) has been required. When an SEM is used, a sample is always irradiated with electrons during observation. This may cause noise and render accurate measurement of electricity impossible. On the other hand, in the case of an AFM, observation can be realized either in an ordinary atmospheric environment or a special atmospheric environment. However, when a multi-tip probe itself is used also as an image-obtaining probe, this may be a hindrance to accurate measurement for reasons such as (1) it is difficult to perform image analysis from signals detected by a plurality of probe tips arranged in a row and (2) the image is contaminated or otherwise damaged by scanning. Further, in the conventional AFM, it is a common practice to employ the light leverage method in which a mirror is mounted on a cantilever to detect displacement. In this case, a sample is irradiated with laser light. Because laser light serves as an excitation energy source to cause surface atoms to enter an excited state, this has a considerable effect on the movement of electrons on a device surface and therefore also impedes accurate measurement of electricity. Alternatively, waves serving as excitation light can be removed by wavelength cutoff using a filter. However, this alternative cannot realize observation in a perfect dark field and would often encounter problems, such as decreases in sensitivity due to attenuation of light intensity. SUMMARY OF THE INVENTION [0007] It is accordingly an object of the present invention to establish such a processing method as to form a microscopic multi-tip probe whose inter-tip distance is sub-micron, and to thereby provide such a microscopic multi-tip probe. Another object of the present invention is to provide an ultra-surface analyzing apparatus for analyzing the ultra-surface of a semiconductor device, the apparatus of which has a function of positioning that does not influence electricity measurement in an extremely small region using the microscopic multi-tip probe. [0008] The multi-tip probe manufacturing method of the present invention comprises the steps of making a cantilevar using lithographic techniques and forming microscopic electrodes at a distal end of the cantilever by sputtering and gas-assisted etching processing using a focused charge particle beam. [0009] This method of manufacturing a multi-tip probe of the present invention comprises the steps of, after making a cantilever using lithographic techniques, performing separation so as to form a plurality of lead portions using lithographic techniques on the cantilever and forming a shunt area at the distal end, and processing the shunt area of the distal end using a focused charged particle beam using sputtering or gas-assisted etching, exposure to X-rays using a stopper, mask aligner, and Synchrotron Orbital Radiation (SOR), or by electron beam rendering and etching so as to form microscopic electrodes. [0010] Further, the method of manufacturing a multi-tip probe of the present invention comprises the steps of; after making a cantilever using lithographic techniques, performing separation so as to form a plurality of lead portions using lithographic techniques on the cantilever, and blasting the distal end of the cantilever with a source gas and irradiating with a focused charged particle beam so as to form microscopic electrodes. [0011] In order to provide the surface characteristic analysis device of the present invention with functions where the microscopic multi-tip probes are put into a non-contact state and an observed image is obtained for a sample surface using an AFM function, a measurement region is specified from the observed image, and the multi-tip probes are positioned at the specified regions and contact is made, drive means are provided for positioning probe positions of a cantilever having a microscopic multi-tip probe of a pitch of 1 .quadrature.m or less at a distal end and a cantilever for AFM use having a dedicated probe at a distal end with a known prescribed gap there between and driving the probes independently so as to be in contact/non-contact states with respect to the sample surface. [0012] One of a bi-metal actuator, a comb-shaped electrostatic actuator, or a piezoelectric microactuator is adopted as the means for driving in a contact/non-contact state. [0013] A self-detecting method where a strain gauge is installed at the cantilever is adopted to enable measurement in a dark field state. [0014] A multi-tip probe of the present invention comprises a cantilever formed using lithographic techniques, a plurality of lead portions formed on the cantilever, and a plurality of electrodes connected to each of the lead portions so that pitch between the electrodes is narrower than pitch between the lead portions. [0015] The multi-tip probe of the present invention may have a configuration provided with a convex bank at the region where the electrode of the cantilever are formed or may be provided with probes at the electrodes. BRIEF DESCRIPTION OF THE DRAWINGS [0016] FIG. 1 is a view showing an embodiment according to the present invention in which an elongated cantilever according to the present invention and its base portion are fabricated; [0017] FIG. 2A is an enlarged view of a distal end portion of the cantilever fabricated by lithography, and FIG. 2B is a view showing a microscopic probe tip formed by the etching process utilizing an FIB apparatus; [0018] FIG. 3 is a view showing another embodiment in which an elongated cantilever according to the present invention and its base portion are fabricated; [0019] FIG. 4A is an enlarged view of a distal end portion of the cantilever fabricated by lithography, and FIG. 4B is a view showing a microscopic probe tip formed by the CVD process according to an FIB apparatus; [0020] FIG. 5 is a view showing still another embodiment in which vertically directed needle-shaped probe tips are formed on a comb-shaped electrode by the CVD process according to an FIB apparatus; [0021] FIG. 6 is a view showing a microscopic probe tip formed in a resilient shape by the CVD process according to an FIB apparatus; A shows a bow type, B shows a coil type; Continue reading... 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