Micro-processing apparatus and method therefor

Abstract: A micro-working apparatus performs fabrication and assembly tasks for micron/nanometer sized objects while observing the progress of work in real-time under at least a pair of optical or electron microscopes to provide simultaneous views from at least two directions, thus offering a spatial visual information regarding the working space which is particularly critical in micro-working. Micro-working is further facilitated by the use of a micro-pallet device specially designed for use in the apparatus, but also offering other application possibilities. Rotational and parallel translation movements provided by the micro-pallet combined with the micro-working capability of the apparatus are utilized to demonstrate the production of micron-sized parts for use in advanced applications of optical and electronic devices.

Description: BACKGROUND OF THE INVENTION Field of the Invention: The present invention relates to a micro-working apparatus used to process/assemble semiconductor and optical devices, and a method of using the micro-working apparatus. Description of the Related Art: There has been a growing need for performing accurate and quick micro-processing or assembly work in a particular atmosphere, to produce advanced devices based on a combination of semiconductor and optical device technologies. Such tasks are performed while utilizing a magnifying means, such as an electron microscope, to observe the behaviour of a workpiece. In a micro-world, a task of processing or assembly while observing the workpiece under magnification at the level of electron microscope can be a totally different experience than that in a world of macro-objects. In a macro-world of working with regular-sized objects, a task of inserting a rod in a hole, for example, is performed by guiding the rod piece against the inner surface of the hole. In this case, the operator can feel a counter force of resistance exerted by the inner surface, and the insertion process is performed while feeling a constant degree of resistance offered by the hole so that the insertion process would proceed without encountering a problem. If some abnormality exists in the process, some warning signs, such as abnormal sounds or other signs of problems, are usually generated to alert the operator. However, in a world of handling microscopic objects, the same task of inserting a fine-rod into a minute hole is a totally different process. In this case, a judgement as to whether the fine-rod is being inserted straight or not must be made strictly visually. If the operator continues to push the rod into the hole without being aware that the bottom of the rod is somehow stuck on the inner surface, continued pushing results in either snapping of the rod or jumping off of the rod by the accumulated elastic stress in the rod, often resulting in disappearance of the rod. Therefore, it is essential to provide an appropriate observation system for avoiding the interference between the hole and the rod. The conventional micro-working methods are not able to offer such system, thus limiting the range of micro-working jobs to be those involving only relatively simple tasks. A remedial step may be to change the location of the observation device in a suitable position to enable more complete observations, however, this process requires focus adjustment each time the location is changed. Further, after focusing the beam to a required location, it is still necessary to remove the spot-abberation which is a time consuming operation. Therefore, it is not realistic to expect to perform micro-working tasks that require frequent changes in the focus. On the other hand, there is a technique of liquid crystal optics providing a three-dimensional imaging, however, this technique is tiring to the operator, and is not suitable for tasks that require a long duration. Also, when the angle of acuity is large in the spatial imaging, although the image may be distinct, the image shape is different from the natural image of the workpiece, and the operator experiences a severe mental stress in performance of the job, leading to possible occupational health problems. Also, although a spatial image includes three-dimensional information to be interpreted by the visual sense of the operator, to be truly useful, it should be accompanied by additional views such as top and side views or views from opposite ends, which should be displayed simultaneously. The conventional micro-working technology is not able to offer such an observation capability. Furthermore, a usual worik includes a task that is more than simple passive information gathering, such as to draw an accurate circle or draw a straight line. To produce quantitative results for such a task, it is necessary to have an undistorted image of the workpiece viewed from a top true center or from a precise lateral side of the workpiece. On the other hand, to observe the progress in processing and anticipate the next step for a workpiece which is constantly undergoing changes, feedback control in real-time is essential, and in this case, the observation must be carried out from the most advantageous position, which is often a perspective view. In some case, in addition to a view from the dead top, views from other angular positions may also be needed. In carrying out micro-fabrication, it is desirable that the job be performed while observing a workpiece under an electron microscope or other observation device. However, there are many practical impediments to arranging the processing apparatus and an observation apparatus in the same working space, because of problems such as the lack of proper equipment space, movement space and contamination of the observation devices by processd particles or secondary emission particles. The fabrication work is usually performed in a vacuum, therefore, to judge the progress in processing, it is necessary to remove the workpiece from the evacuated environment, observe the results and return the workpiece in the vacuum environment, resulting that the apparatus needs to be evacuated each time an observation is made. Furthermore, when micro-fabricating fine-structures on multiple faces of a workpiece, it is necessary to reposition the workpiece for each fabrication of a fine-structure, resulting in time-consuming and inefficient fabrication. In particular, when it is necessary to produce a fine curvature-structure having a rotational symmetry by rotating the workpiece, an extremely tedious operation is needed to align the two axes of the workpiece and the rotation device. When this type of operation has to be carried out a number of times for each processing step for the multiple of surfaces, the work efficiency and the precision are drastically reduced. Furthermore, a complex device is required to perform such an alignment task, and to provide such a device for each work station is not only a complex and costly task, but also presents a serious disadvantage of requiring the necessary equipment space. With reference to the prior art attention is drawn to DE 38 02 598 C1 which discloses a scanning electron microscope in which the electron optics and the detectors are supported by a goniometer device and the sample support is provided in the form of a rigid, fixed sample table. Further EP 0 200 333 A2 is directed to an ion beam processing apparatus using a finely focused beam of ions produced from an ion source, said apparatus includes a beam of electrons directed onto the target which neutralizes the charge created by the incident ion beam. Ultra-precise control of the etching process is achieved by monitoring the particles that are sputtered from the target surface. DE 42 26 694 A1 discloses a method for separating a predetermined section from a chip of a integrated circuit. The method uses processing with a focused ion beam from at least two directions of incidence and the separated sample is connected mechanically with a probe. The separated sample is held and can be moved by the probe. Additionally, US 4,663,511 shows an improved optical system for providing a stereoscopic viewing field to the operator, said optical system is particularly suited for use in various machines such as electron or laser beam welding and drilling machines. In accordance with the invention a micro-processing apparatus as set forth in claim 1 is provided. Preferred embodiments are disclosed in the dependent claims. SUMMARY OF THE INVENTION It is an object of the present invention to provide an energy beam assisted micro-working apparatus so that a fabrication process including aligning of masking device and the workpiece as well as assembly of micro-sized workpieces can be carried out while observing the workpiece in real-time. Another object of the present invention is to provide a micro-pallet device for handling of the workpiece through a number of work stations related to fabricating and assembling operations. A micro-working apparatus of one embodiment comprises: a working device disposed in a working space surrounding the working area; positioning means for adjusting a relative position of the processing and/or assembly means with respect to the workpieces; and not less than two observation means for providing magnified real-time images of progress in micro-working from not less than two directions of view. According to the apparatus, at least two observation devices are used to observe the progress of work from at least two viewing directions. The operator is able to perform the task while obtaining visual information from at least two directions. Because the necessary visual information can be supplied simultaneously from more than one direction, micro-working tasks can be carried out much more efficiently and quantitatively, which have been difficult to perform in the conventional apparatus which supplies only unidirectional visual information. The operator fatigue is also reduced considerably. The apparatus thus enables to produce fine-parts for use in optical devices and in other advanced fields of technologies. An aspect of the apparatus is that an energy beam is used to produce fabrication while observing the progress in micro-working through at least two observation devices. Another aspect of the apparatus is that a micro-manipulator is used while observing the progress in micro-working through at least two observation devices. Still another aspect of the apparatus is that micro-working is performed in a hermetically sealed environment while observing the progress in micro-working through at least two observation devices. Still another aspect of the apparatus is that the observation devices includes optical, laser and electron microscopes which can be used to observe the progress in micro-working through at least two observation devices. Still another aspect of the apparatus is that the observation devices are movable with respect to the workpieces, so as to enable positioning the observation devices to provide the best suited visual information on the work under progress. Still another aspect of the apparatus is that the observation devices are movable in a parallel translational direction so as to follow the progress in linear micro-working. Still another aspect of the apparatus is that the observation devices are movable along a spherical surface, thereby permitting to move the observation devices in circular paths with the center at the center of the sphere to provide different angles of viewing the progress in micro-working. Still another aspect of the apparatus is that the apparatus is provided with image processing devices to present the images on the observation devices so that quantitative observations can be made to determine the position of the workpiece to enable more precise micro-work to be carried out. Still another aspect of the apparatus is that the apparatus is provided with a control device to automatically control the relative positions of the workpiece with respect to the beam source or the mask member on the basis of the images received from the image processing devices. The present invention presents another type of micro-working apparatus comprising: workpiece support means for supporting the workpiece disposed in a vacuum vessel; an energy beam source for irradiating an energy beam towards the vacuum vessel; and observation means for observing progress of fabrication of the workpiece; and positioning means for relatively positioning the workpiece support means either in an irradiation position for irradiation of the workpiece with an energy beam or in an observation position for observation of progress of fabrication with the observation means. According to another aspect of the apparatus, the workpiece can be placed either in the irradiation position or the observation position within a chamber to perform various processing steps so that observation and micro-working may be carried out alternatingly without disturbing the vacuum environment. Especially, when performing micro-processing work using the mask members, it is necessary frequently to adjust the relative positions, to switch the mask members, or to confirm the progress in micro-working, and even in such cases, it is possible to continue the work without disturbing the vacuum environment. This approach permits the work to be carried out without once exposing the workpiece to the atmosphere so that a high degree of cleanliness can be maintained, thereby improving the product quality by avoiding surface oxidation and contamination. Furthermore, because of the elimination of evacuating and leak testing, the work efficiency is improved and processing time is shortened. An aspect of the apparatus is that the positioning device moves the workpiece between the irradiation position and the observation position. Still another aspect of the apparatus is that the positioning device moves the energy beam source and the observation devices. Still another aspect of the apparatus is that it is provided with a workpiece support device having a micro-movement adjusting device so that the workpiece can be moved together with the support device to the observation position to adjust positioning or to observe the progress in micro-working. Still another aspect of the apparatus is that mask member holding means is disposed in a specific location between the energy beam source and the workpiece to mask the workpiece from irradiation, so that fine-patterns on the mask member can be transferred onto the workpiece while controlling the degree of exposure to the beam energy. Still another aspect of the apparatus is that the holding means comprise micro-movement means for providing micro-positioning of the mask member with respect to the energy beam so as to permit relative movement of the mask member while observing the progress in micro-working in the observation position. Still another aspect of the apparatus is that a plurality of exchangeable mask members having different fine-patterns are provided, thereby permitting different fine-patterns to be duplicated on one surface or on different surfaces. This arrangement permits a series of masking steps, such as mask member exchange, position adjustment of the mask member with respect to the workpiece, to be carried out precisely and quickly without disturbing the vacuum environment, thereby avoiding oxidation contamination and problems of positioning errors. Still another aspect of the apparatus is that the observation means include not less than two observation means, each observation means providing a different field of view of working areas on the workpiece, thereby providing a spatial view of the micro-work in progress. Still another aspect of the apparatus is that the positioning means include a parallel translation device, thereby permitting a reciprocating motion between the observation position and the irradiation position. Still another aspect of the apparatus is that the positioning means include a rotational movement device, thereby permitting a reciprocating rotational motion between the observation position and the irradiation position. Still another aspect of the apparatus is that the energy beam is selected from the group consisting of a fast atomic beam, an ion beam, an electron beam, an atomic beam, a molecular beam, a laser beam, a radiative ray beam and an X-ray beam. By using an electrically neutral beam, such as a fast atomic beam, the superior directionality of the beam is maintained in any type of material, thereby enabling to produce precise fine-structures such as deep channels having precisely vertical walls and flat bottom surfaces. Ion beams are useful in fabricating electrically conductive materials such as metals. Electron beams can be produced as a fine-beam or a divergent beam, and both types are useful in combination with reactive gases to activate the surface to be processed of the workpiece under highly controllable conditions. Laser, X-ray and radiative ray beams provide different energies and wavelengths and offer different degrees of surface reactivity. For micro-processing work, these beams can be used directly to remove surface materials, or can be used in conjunction with reactive gases to provide chemical surface activation. These beams can be selected as needed, depending on the size of the fine-structure to be produced and the reactivity of the surface material. When the size of the ultra-fine structures becomes smaller than the wavelength of a laser beam, for example, fabrication becomes usually very difficult, therefore, X-rays or radiation beam is more suitable. Atomic or molecular beam is a low energy beam, and is useful in avoiding the generation of surface damages. In summary, the choice of an energy beam should be based on the need of each particular application. Still another aspect of the apparatus is that the observation means include a single observation means or a combination of observation means selected from the group consisting of optical microscope, laser microscope and electron microscope, thereby offering a wide choice in the observation method. Optical method is simple, and laser method offers a high coherency of the beam energy over a long working distance and the scanning secondary electron microscope provides a higher magnification capability. Further, there is provided a micro-pallet means for holding a workpiece and positioning the workpiece with respect to micro-working means, comprising a pallet body and a holding section freely rotatably disposed on a shaft member fixed on the pallet body. This pallet arrangement permits the workpiece to be disposed on the holding section and transported so that in-situ micro-working can be performed quite readily. This approach is particularly effective when a series of process operations are to be performed on the workpiece serially by rotation of the workpiece. There is no need to reposition the workpiece, thus increasing the precision of work and the operational efficiency. Further, there is no need to provide a positioning device for each station, thus leading to a compact and simplified overall construction of the apparatus, thereby lowering the cost of manufacturing the apparatus. The shaft member of the pallet means is provided with power transmission means for freely coupling or decoupling the shaft member with an external driving source. The shaft member of the pallet means has a transmission mechanism which can be coupled or decoupled to an external driving device, thereby eliminating the need for having a driving device on the pallet means, and providing a compact and light-weight transporting device, and the cost of the overall apparatus can be lowered. The power transmission means of the pallet means include pulleys and belts, gears and friction rollers all of which are simple and effective methods of power transmission. The shaft member of the pallet means is provided with pre-stressed bearings for limiting a wobble of the shaft member to not more than 10 µm. The bearings may be angular ball bearings or deep channel ball bearings. Pre-stressing minimizes a slack between the moving and stationary races of the bearing, thereby limiting the wobble to less than 10 µm to produce fine-structures with high precision or to perform micro-assembling. The holding section of the pallet means is provided with a centering device for aligning a rotational center of the shaft member with a rotational center of the workpiece by rotational and parallel translational movements, thereby eliminating shaft wobbling. When pulleys and belts are used to transmit the driving power to the micro-pallet, the workpiece support shaft and the drive shaft are moved into position to couple with each other by winding the belt to the shafts to transmit the driving power from the drive shaft to the workpiece support shaft. When gears are used to transmit the driving power to the micro-pallet, the workpiece support shaft and the drive shaft are moved into position so that the gears are coupled with each other to transmit the driving power from the drive shaft to the workpiece support shaft. When friction rollers are used to transmit the driving power to the micro-pallet, the workpiece support shaft and the drive shaft can be driven by the contact of the rollers themselves or by the contact of rollers with other transmission devices to transmit the driving power from the drive shaft to the workpiece support shaft. It is preferable that one of the rollers be elastic or that the contact is made elastically. For example, rollers may be driven by friction, or a combination of a roller and a belt may be used to transmit the driving power. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an embodiment of the apparatus for performing a micro-working operation. FIG. 2 is a perspective view of another embodiment of the method for performing a micro-working operation. FIGS. 3A∼3B are perspective views of still another embodiment of the method for performing a micro-working operation. FIG. 4A∼4D are illustrations of still another embodiment of the method for performing a micro-working operation: where FIG. 4A is a perspective view; FIG. 4B and 4C are illustrations of enlarged images; and FIG. 4D is an illustration of a geometric relationship of the related sections. FIG. 5 is a perspective view of still another embodiment of the method for performing a micro-working operation. FIG. 6 is a perspective view of an embodiment of the processing apparatus for performing a micro-working operation. FIG. 7 is a perspective view of a of the processing apparatus shown in FIG. 6 for performing a micro-working operation. FIG. 8 is a perspective view of still another embodiment of the processing apparatus. FIG. 9 is a cross sectional view of still another embodiment of the processing apparatus. FIG. 10A∼10B are cross sectional views of a of the processing apparatus shown in FIG. 9. FIG. 11 is a perspective view of still another embodiment of the processing apparatus. FIG. 12 is a perspective view to show the operation of the processing apparatus shown in FIG. 11 for performing a processing operation. FIG. 13 is a cross sectional side view of the processing apparatus shown in FIG. 11. FIG. 14 is an illustration of the operation of another embodiment of the processing apparatus. FIG. 15 is a perspective view of a processing apparatus. FIG. 16 is a perspective enlarged view of the essential parts of the processing apparatus shown in FIG. 15. FIG. 17 is a schematic view of a cross section of the device shown in FIG. 16. FIG. 18 is a perspective view of still another embodiment of the micro-working apparatus. FIG. 19 is a schematic illustration of the cross section of the apparatus shown in FIG. 18. FIG. 20A-20B illustrate an example of the essential steps using the processing apparatus. FIG. 21 shows an example of an optical fiber made by the method shown in FIG. 20. FIG. 22A∼22B show another example of steps using the processing apparatus. FIG. 23 shows a step of making a fine-structure by the steps shown in FIG. 22. FIG. 24A-24C are illustrations of an example of the processing or assembling operation using the apparatus shown in FIG. 18. FIG. 25A and 25B are perspective views of still another processing apparatus. DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, preferred embodiments will be explained with reference to the drawings. FIG. 1 is a perspective view of an embodiment of the micro-working apparatus of the present invention, and is suitable for performing micro-working, i.e. processing and/or assembly operations, on workpieces (minimum size of the order of several hundred microns). The apparatus comprises: a work pedestal 1 disposed in the central working area; a pair of assemblers 2, disposed in a first working space surrounding the work pedestal 1; and, in a second working space is disposed, a pair of magnifying observation devices (scanning secondary electron microscopes) 4, 5 surrounding the first working space. The pedestal 1 is disposed in the center of the apparatus base 6 and is provided with an XYZ-stage for producing movements in the horizontal and vertical planes. A pair of opposing semi-circular rails 7, 8 (first rails) are provided to surround the pedestal 1, and each of these rails are provided with sliders 9, 10 mounted slidably on the respective rails. The sliders 9, 10 are provided with arc-shaped support columns 11, 12, respectively, which are each provided with slider 13, 14. Each of the sliders 13, 14 is provided with a micro-manipulator 2, 3 (assembling devices) for performing assembly operations. Another of the apparatus would be to include an energy beam source on one slider 13, and a manipulator 3 on the other slider 14. When such an apparatus is to be used for an energy beam-assisted processing, the manipulator 3 is used as a device for holding a mask member having some specific fine-patterns for transmission of the energy beam. Also, in the above example, both observation devices are electron microscopes, but it is permissible to use optical or laser microscopes or a combination of optical, laser and other applicable magnifying devices, depending on the application. It is not necessary to limit the number of observation devices to two, so three or more devices can be installed. Further outwards of the first rails 7, 8, on the apparatus base 6, there are disposed second rails 15, 16 concentrically with the first rails 7, 8. Each rail is provided with freely slidable sliders 17 and 18, respectively, with arc-shaped columns 19, 20 of certain lengths erected, as well as sliders 21, 22, respectively. Electron microscopes 4, 5 are disposed on the sliders 21, 22 to provide a field of view including the working area A. One of the columns 19, 20 extends to the top region of the working area A so as to permit observation of the working area A from the top true center. Each of the sliders 9, 10, 13, 14, 17, 18, 21 and 22 may include some driving devices such as motors so as to enable moving by remote control to a specific location. FIG. 1 illustrates an example of a micro-working operation involving a first workpiece W1 to be inserted into a hole 23 provided in a second workpiece W2. The fine-rod piece W1 is held with a manipulator 3 and is inserted into the hole 23 while going through positional alignment by rotational and parallel movements. In performing such a step, the operator observes the movements of the workpieces on screens of both observations devices (electron microscopes in this case) 4, 5 as well as through the unaided visual observation, and operates the driving devices so as to move the sliders 9, 10, 13, 14, 17, 18, 21 and 22 along the rails 7, 8, 15 and 16 and columns 11, 12, 19 and 20. By such a process, the observation devices 4, are made to move along the spherical surfaces in relation to the workpieces W1, W2 to obtain image data seen in the direction necessary to properly perform the operation. According to this method, observation of workpieces can be made simultaneously from the top true center or at the precise lateral position so as to enable detailed observation of the positional relationships in the working area, embodied by the fine-rod piece W1 and the hole 23. The observation can be made as many different directions as necessary for the performance of the task, and serves to provide an invaluable aid in performing the job well. FIG. 2 shows a view of the working area close to the working area A in an example of processing using an energy beam. A mask M, acting as a mask member, is placed on a substrate workpiece W3, and an energy beam, such as fast atomic beam (FAB) is irradiated from above. The operational steps for transferring the pattern on the mask M onto the workpiece W3 may involve moving the mask M to control the amount of surface material removed by controlling the duration of exposure to FAB irradiation. The necessary movement is a parallel movement of the mask M with a separation distance of about 100 µm, for example, between the mask member and the surface to be processed on the workpiece W3. In this case, the mask M is disposed on a rotation stage 25 provided on the XY-stage 24 disposed in the working area. One observation device 5 of the two observation devices is lowered to an approximately level position. The mask M and the workpiece W3 is aligned horizontally by means of the observation device 4 in a top direction, and the parallel alignment and the separation distance are measured by means of the observation device 5 in a horizontal direction. If it is necessary to tilt the mask M to align the mask M parallel to the workpiece W3, the positional alignment between the two is lost and additonal adjustment is necessary. However, in the method of the present invention, observations are being made through two observation devices 4, 5 simultaneously, and therefore, there is no need to repeat adjusting the focus of one observation device many times so as to obtain a proper alignment adjustments. FIGS. 3A, 3B show an example of repairing a line connection in a large-scale integrated (LSI) circuit. In this repair operation, it is required to sever the section "a" with a focused ion beam. From an observation of a top view only as in FIG. 3A, it is not possible to judge when the line is completely severed. By positioning the observation device 5 at an oblique angle as shown in FIG. 1, it is possible to confirm that the line has been severed, by enabling to observe the severed surface "b" at an angle as shown in FIG. 3B. In performing such an operation, it sometimes occurs by some external disturbance that the processing regions become shifted from the target region, therefore, to prevent such an occurrence, it is necessary to simultaneously watch the top view with the observation device 4. FIGS. 4A-4D illustrate an operation to move a needle tipped tool 26 attached to a slider 14 to a mark 27 placed on a workpiece W4 while observing the motions through two observation devices (scanning secondary electron microscopes) 4, 5. First, as shown in FIG. 4A, by observing the image from the first device 4 disposed on the top, the tip of the tool 26 and the mark 27 are aligned, as illustrated in FIG. 4B. Based on the image shown on the second device 5, the distance between the tip of the tool 26 and the mark 27 is measured as "1", as indicated in FIG. 4C. From the geometry shown in FIG. 4D, the actual distance "h" between the tip of the tool 26 and the mark 27 is given by the following expression: h = l/cos , and it thus follows that the tip of the tool 26 is made to contact the mark 27 by moving the Z-stage by an amount equal to "h". To illustrate the operation, the mark 27 was drawn on the workpiece W4, but in an actual operation, software programming can be used to compute the marking location in the same manner without actually marking the surface. FIG. 5 illustrates a process of installing a baby-chip 29 having a custom LSI circuit on a general purpose mother-chip 28. Such a baby-chip 29 is utilized in cases when the 5 production method for the baby chip 29 can be customized or when the production method is different from that for the mother-chip 28 or when the yield for the baby-chip is low. The method involves a first step of local planarizing of the installation region with a diamond needle, positioning of the baby-chip 29 in the installation region and local film deposition to provide a line connection 30. Subsequent inspection is performed by the use of probe tips 33, 34 attached to the ends of tools 31, 32 which are mounted on the slider 14. If the installation process is improper, the connection is severed by etching with a focused ion beam (FIB), and the connection steps are repeated. FIG. 6 is a schematic drawing of an embodiment of the micro-working apparatus of the present invention. An outline of a processing chamber 111 is shown by the solid lines shown in the illustration, and the processing chamber 111 comprises a hermetically sealed space which is maintained at either a vacuum atmosphere or a low pressure inert atmosphere. An energy beam source 112 is disposed at an upper portion of one end of the processing chamber 111. A downward-viewing optical microscope 113 is disposed on an upper portion of the other end of the chamber 111 while a horizontal-viewing optical microscope 114 is disposed on a side surface at the other end of the chamber 111. Inside the chamber 111, there is a pedestal 115 freely slidably mounted on a pair of rails 116 disposed parallel to one wall of the chamber 111. Below the center of the pedestal 115, there is a driving device 117 which moves the pedestal 115 along the rails 116, thereby producing a reciprocating motion of the pedestal 115 between an irradiation position below the energy beam source 112 and an observation position viewed by the optical microscope 113. In the illustration, the driving device 117 comprises a screw shaft 119 driven by a motor 118 to provide precise positioning at the irradiation position and the observation position. There is no particular restriction to the construction of the driving device, and so long as the precise positioning is achievable, it is permissible to use piezo-electric elements in combination with a linear motor, for example. The pedestal 115 is provided with a specimen holding stage 120 for holding a workpiece W and an opposing mask member holding device 122 for holding a mask 121. These holding devices 120, 122 are provided with positioning devices 123, 124 to position the workpiece W or the mask 121 which are equipped with actuators for producing rotational or parallel translation movement in the X, Y or Z direction. The operation of this apparatus is as follows. The pedestal 115 is moved to the observation spot, where the mask 121 and the workpiece W are aligned by operating the positioning devices 123, 124 while observing the motions under the optical microscopes 113, 114. The pedestal 115 is then moved to the irradiation spot below the energy beam source 112 to perform a processing work. When it is necessary to observe the progress of processing or to perform adjustments in positioning, the driving device 117 is used to move the pedestal 115 to the observation spot to observe the state of the workpiece W under the microscopes 113, 114, subsequently, the pedestal 115 is returned to the irradiation spot to continue the processing work. As described above, because the micro-working apparatus is provided with two observation devices 113, 114, it is possible not only to observe the position and the shape of the workpiece in a three-dimensional space but also to finely adjust the relative parallel positioning of the workpiece with resect to the mask. When fabricating a pattern on the mask 121 on the workpiece W by using a mask 121 in combination with a highly linear energy beam, such as FAB, the correct position of the mask 121 to the workpiece can be determined readily, and positioning can be adjusted quickly and precisely. In this case, if the pattern dimensions are of the order of several tens of micrometers, optical microscopes 113, 114 having a magnification higher than x500 would be quite adequate for the task. In this apparatus, because the irradiation spot and the observation spot are separately provided, there is less problems of particles emitted by the etching process directly affecting the performance of the observation devices. In this case, a curtain to separates the spaces may be provided to further reduce the influence of such an effect when the pedestal 115 is in the irradiation spot. FIG. 7 shows a of the previous micro-working apparatus comprising a plurality of masks 121 on a mask holding device 121a so that different patterns can be processd on the workpiece W by exchanging the masks 121 during the irradiation step. In this case, by pre-positioning the masks 121 with respect to the workpiece W before commencing the irradiation step, it is only necessary to rotate the mask holder 121a to exchange the mask during the irradiation step, thus there is no need to reposition the masks. It is of course permissible to return to the observation spot to readjust the relative positioning of the mask 121 with respect to the workpiece W. FIG. 8 shows another embodiment of the micro-working apparatus having a turntable base 125 which is driven by a rotation device 126 disposed below the turntable base 125 to rotate the turntable base 125 about a central vertical axis. The workpiece W and the masks 121 are freely movably held in place by their respective holding devices 120, 122. In this embodiment, the irradiation spot and the observation spot are separated so that the workpiece W and the mask 121 can be interchanged by a rotation of the turntable base 125 through 180° . This apparatus also permits instant judgement to be made, while leaving the workpiece W in the vacuum, whether to continue processing or exchange the masks 121 by observing the progress of the work so that the process may proceed smoothly without being interrupted. The embodiment of the micro-working apparatus shown in FIG. 9 includes a spherical processing chamber 131 having a workpiece W disposed at about the center thereof. The energy beam source 132 is disposed directly above, and each of the two optical microscopes 133, 134 is placed, respectively, at an angle of about 45° from the top and the bottom to view the center region of the chamber 131. The pedestal 135 is provided with a drive mechanism (not shown) to rotate about a horizontal axis 136 and a vertical axis 137 so that the holding devices 120, 122 for holding workpiece W and the mask 121 can tilt or rotate about in a horizontal plane. The fabrication is performed by positioning the mask 121 and the workpiece W in the processing spot directly below the energy beam source 132, and observations are made by tilting the pedestal 135 so that the mask 121 and the workpiece W will be in the field of view of the optical microscopes 133, 134. By rotating the pedestal 135, observations regarding the positional alignment between the workpiece W and the mask 121 as well as the progress in micro-working on the surface to be processed of the workpiece W may be made both during the fabrication as well as after the fabrication by means of the optical microscopes 133, 134. The advantage of this configuration is that the distance of movement is short, and the observation spot and processing spot can be accessed quickly by rotation or tilting of the pedestal 135 about the axes 136, 137, compared with the movement requiring parallel translation and rotation motions. The observation devices in the apparatus shown in FIG. 9 are susceptible to the effects of debris produced during processing, because of the short distances between the processing spot and the observation spot. When using a corrosive gas or reactive gas in the processing chamber, contamination of the detectors and the beam sources of the electron microscopes or the lenses of the optical microscopes can be prevented by using a masking arrangement shown in FIGS. 10A, 10B. The masking device shown in FIG. 10A comprises a shutter 150 or a valve, disposed at the leading end of the optical microscopes 133, 134, which is displaced during observations. Instead of the shutter 150, the masking device shown in FIG. 10B comprises a bellows 152 having a glass window 151 so that the hermetically sealed spaces may accommodate the optical microscopes 133, 134. FIGS. 11∼13 show a of the apparatus shown in FIG. 9 having a spherical processing chamber 131, an energy beam source 132 and observation devices 133, 134 with the difference that the base table 138 is rotatable about a horizontal axis 139. The horizontal axis 139 is disposed so that it is perpendicular to the plane containing the axes of the energy beam source 132 and the observation devices 133, 134. When the table base 138 is rotated about the axis 139, the workpiece W, the mask 121 are successively brought into the spots. Changes of orientation angles are made externally to the processing chamber 131, by turning the handle 141 provided on the link mechanism 140 disposed opposite to the rotation axis 139. FIG. 14 shows a stationary base 141, having the holding devices 120, 122 for the mask 121 and the workpiece W, and the rotation plate 144 is provided with an energy beam source 142 and a top observation device 143. In this configuration, the top observation device 143 rotates but the other observation device 145 is a stationary side viewer device and only permits observation of the mask 121 and the workpiece W from the lateral side of the apparatus. The driving and supporting mechanisms for the rotation plate 144 are hermetically sealed in the processing chamber using magnetic fluid seals or O-ring seals. FIG. 15 shows a micro-pallet device (shortened to micro-pallet or pallet hereinbelow) being used in micro-processing work using an energy beam. The micro-processing apparatus A comprises an energy beam source 201 providing an energy beam to irradiate a workpiece 203 through a mask 202 disposed in the beam path to control the exposure to the beam energy. The micro-pallet P has a cutout section 205 in the pallet body 204 and a shaft member 206, spanning across the space of the cutout section 205, supported by bearings (not shown). The shaft member 206 protrudes out of the side surface of the pallet body 204, and is provided, at its tip, with a holding section 207 for holding a workpiece 203. The shaft member 206 has a driven gear 208 in the cutout section 205 for transmitting the rotational drive force to the workpiece 203. For the bearings, angular ball bearings and deep groove ball bearings are used to provide pre-stressing between the rotary and stationary rings to eliminate the spacing between the inner and outer rings to limit the wobble of the shaft member 206 to less than 10µm. Above the base 209 of the apparatus A, an XY-stage 210, disposed opposite to the energy beam source 201, is used to support a motor base 212 for mounting an electrical drive motor (rotational drive device) 211 as well as a pallet base 213. The drive motor 211 revolves to drive a transmission gear 218 through a transmission shaft 214, pulleys 215, 216 and a belt 217 provided on the side surface of the pallet base 213. A portion of the transmission gear 218 protrudes above the surface of the pallet base 213 and, by moving the pallet P placed on the pallet base 213 horizontally, the gear 218 can be engaged with the driven gear 208. The apparatus A further comprises: a mask holding device (Z-stage) 219 for holding a mask 202 between the energy beam source 201 and the workpiece 203; and a pallet-pressing device 220 having an L-shaped cross section. Both of the devices 219, 220 are freely vertically movable. The section opposite to the cutout section 205 on the pallet body 204 is provided with a flat section 222 for coupling to an arm 221 of a robot, for example. FIGS. 16, 17 show details of the holding section 207 having a micro-positioning device 223, disposed at the tip of the shaft member 206, which is used to align the centers of the shaft member 206 and the workpiece 203. The micro-positioning device 223, shown in FIG. 16, includes a tip section 224 of an elastic hinge structure which is capable of providing mutually orthogonal micro-movements in a plane perpendicular to the axis of the shaft member 206. The tip section 224 of a square cross sectional shape is provided near its base region with two square holes 225, 226 oriented in two perpendicular directions thus forming two pairs of opposing parallel sections 225a, 226a. The end of the tip section 224 has an opening 227 for receiving an optical fiber 203 (micro-sized workpiece) and is surrounded with a cylindrical outer ring 228 fixed to the shaft member 206. The outer ring 228 has an M2 female threads 229, in each quadrant at an angle of 30° to the shaft axis as shown in FIG. 17, fitted with an M2 precision male bolt 230. FIG. 18 and 19 show an overall view and a side view of the micro-working apparatus provided with a processing chamber 240 having the processing apparatus A presented earlier, and an assembly chamber 241 designed primarily for assembling of fine-parts. The two chambers 240, 241 are hermetically sealed and are connected to each other through a gate valve (hermetic valve) 242, as shown in a side view of the apparatus A illustrated in FIG. 19. The assembly chamber 241 has a central assembly stage 243, surrounding manipulators 244, an energy beam source 245, and observation devices 246. The processing chamber 240 and the assembly chamber 241 are connected with rails 247 for transporting a transport robot 248 carrying a micro-pallet P. The transport robot 248 is provided with four arms 249 having four rotation links, and the length of its body section 250 is longer than the distance between the rails caused by the presence of the gate valve 242, thus enabling the robot 248 to cross over the separation space. The workpiece 203 is thus able to move freely between the two hermetically sealed chambers 240, 241 by being mounted on the micro-pallet P and transported by the robot 248, to be manufactured into a complex shaped part. Next, a case of fabricating an optical fiber using the micro-working apparatus will be presented. First, an optical fiber 203 is fixed with a suitable jig into a hole 227 of the holding section 207 of the shaft member 206 of the micro-pallet P. Using the arms 249 of the robot 248, the micro-pallet P is transported to the pallet base 213, and is positioned in place by means of the XY-stage 210. The pallet pressing device 220 is lowered to press down the pallet P onto the pallet base 213. By this process, the driven gear 208 and the transmission gear 218 are coupled to each other, and the rotation motion of the drive motor 211 is transmitted to the optical fiber 203 attached to the pallet P, through the timing belt 217, gears 218, 208 and the shaft member 206. The method of centering is explained below. The shaft member 206 is made to be wobble-free, but if the attached optical fiber 203 wobbles, it is because the centers of the optical fiber 203 and the shaft member 206 are not coincident. To correct such a situation, the free end of the parallel sections 225a, 226a are pressed by the precision bolts 230 to force the workpiece 203 to move relative to the shaft member 206 within a plane at right angles to the shaft axis. Because the precision bolts are threaded at an inclined angle to the axis, one turn of the bolt produces a movement equal to a fractional portion of the thread pitch. For example, the thread pitch of M2 screw is 0.4 mm per revolution, but the 30° angle of the bolt produces a pressing distance of 0.2 mm against the parallel sections 225a, 226a. The pressing process is continued gradually to align the center of the optical fiber 203 with the center of the shaft member 206. To perform an etching process on the optical fiber 203 using the apparatus A, an energy beam from an energy beam source 203 is irradiated through a slit of a mask 202. By etching the optical fiber 203 while rotating it with the drive motor 211, a three-dimensional fine-structure is produced on the optical fiber 203. FIG. 20A shows an example of such a fine-structure. The optical fiber 203 is attached to the shaft member 206 of the pallet P, and the optical fiber 203 is exposed to FAB irradiation through a mask 202 having a fine pattern 251 protruding into an opening 205 as shown in FIG. 20B. The fine structure shown in FIG. 21 having a spherical end is produced on the optical fiber 203 by this method, and can be used as a lens in optical communications. FIG. 22A shows an example of a needle-tipped fine-structure, shown in FIG. 23, produced on an optical fiber 203 using a mask 202 having a long narrow slit pattern 252 and irradiating with FAB. The product shown in FIG. 23 is a (needle-tipped) fiber probe 253 which is used in scanning secondary electron microscope (STM). In this process, the mask 202 mounted on a XY-stage 210 is reciprocated in the direction of the fiber axis, as illustrated in FIG. 22B, at a controlled speed so as to control the degree of exposure to the beam energy. After the processing is completed, the optical fiber 203 together with the pallet P is removed from the processing chamber 240, and is transported to the assembly chamber 241 to be assembled into a micro-working machine or the like devices of ultra-fine dimensions. FIGS. 24A-24C illustrate fabrication steps for a probe 254 for use with both scanning near-field optical microscope (SNOM) and atomic force microscope (AFM). The former technique provides combined qualitative information regarding the distribution of light absorption and the surface configuration, and the latter technique provides quantitative information regarding the surface configuration. Therefore, by using a probe 254 which can be used for both techniques, it is possible to obtain quantitative information regarding the distribution of light absorption for any given surface configuration. The probe 254 provides AFM information through a plate spring 255 having a needle tip 256 shown in FIG. 24A, and SNOM information is provided through a gold plated surface probe 257 and a gold plated reflection mirror 258 which are integrally formed in an optical fiber probe 254. The probe 254 is produced in the processing chamber by heating an optical fiber 203 with a heater 259 to bend the tip using a bending jig 260 as illustrated in FIG. 24B. In the next step, fabrication of the reflection mirror 258 is carried out to polish the surface of the optical fiber 203 with an energy beam using a mask 202 having a narrow slit 261, as illustrated in FIG. 24C. Subsequently, this region is gold plated in the processing chamber. FIG. 25A shows another micro-pallet device, having a friction-driven mechanism for the transmission of motor torque to the pallet. The rotational motion of the drive motor 272 is transmitted to a shaft 273 through a timing belt 271, and is transmitted further to a roller 274 disposed at the fixed end of an arm 276. The arm 276 is free to rotate, and rotates with the roller 274 until it is stopped by a metal roller 278 provided on the pallet. In this device, the rotation of the arm 276 is converted to a pressing force of the roller 277 against the metal roller 278. The metal roller 278 is thus driven by the frictional force of the timing belt 275. The metal roller 278 is supported by a bearing 279 shown in FIG. 25B. The entire structure of the bearing 279 is made as a unit by wire electric discharge machining, and is designed to hold a shaft with three plate spring members 280 pushing the shaft from different directions. This type of pre-stressed shaft configuration provides smooth precise rotation. There is some sliding between the plate springs 280 and the shaft, but the shaft rotates at about 10 rpm, there is no danger of frictional wear. It should be noted that the objects and advantages of the invention may be attained by means of any compatible combination(s) particularly pointed out in the items of the appended claims.

Claims: A micro-processing apparatus for performing micro-processing of a workpiece using an energy beam, comprising: workpiece support means (120; P) for supporting said workpiece disposed in a vacuum vessel; an energy beam source (112; 132, 142; 201) for irradiating an energy beam towards said vacuum vessel; observation means (113, 114; 133, 134; 143, 145; 246) for observing progress of micro-processing of said workpiece; characterized by positioning means (115-119; 122, 126; 136, 137; 138, 135, 140, 141; 144; 247, 248) for relatively positioning said workpiece support means (120; P) either in an irradiation position for irradiation of said workpiece with an energy beam or in an observation position for observation of progress of micro-processing with said observation means. A micro-working apparatus as claimed in claim 1, wherein said positioning means (116-119; 122, 126; 136, 137; 139, 140, 141; 247, 248) reciprocate said workpiece support means between said irradiation position and said observation position. A micro-working apparatus as claimed in claim 1, wherein positioning means (144) selectively move either said energy beam source or said observation means with respect to said workpiece support means. A micro-working apparatus as claimed in one of the preceding claims, wherein said workpiece support means (120; P) include micro-movement means for providing micro-positioning of said workpiece. A micro-working apparatus as claimed in one of the preceding claims, wherein said apparatus is provided with holding means (122; 219) for holding mask means (121; 202) for masking said workpiece from irradiation, disposed in a specific location between said energy beam source and said workpiece. A micro-working apparatus as claimed in claim 5, wherein said holding means (122, 219) comprise micro-movement means for providing micro-positioning of said mask member (121; 202) with respect to said energy beam. A micro-working apparatus as claimed in claim 6, wherein said mask means (121; 219) comprise a plurality of exchangeable mask members having different fine-patterns. A micro-working apparatus as claimed in one of the preceeding claims, wherein said observation means include not less than two observation means, each observation means providing a different field of view of working areas on said workpiece. A micro-working apparatus as claimed in one of the claims 1, 2, or 4 to 8, wherein said positioning means include a parallel translation device (116-119). A micro-working apparatus as claimed in one of the claims 1 to 8, wherein said positioning means include a rotational movement device (122, 126, 136, 137; 138, 139, 140, 141; 144) A micro-working apparatus as claimed in one of the preceding claims, wherein said energy beam is selected from the group consisting of a fast atomic beam, an ion beam, an electron beam, an atomic beam, a molecular beam, a laser beam and a radiation beam. A micro-working apparatus as claimed in one of the preceding claims, wherein said observation means include a single observation means or a combination of observation means selected from the group consisting of optical microscope, laser microscope and electron microscope. A method for performing micro-working using apparatus claimed in one of the preceding claims, wherein said micro-working includes a single processing or a combination of two or more processes selected from the group consisting of mechanical processing, etching, film forming, surface treating, joining, assembling, analyzing and adjusting processes.

Inventors: HATAKEYAMA MASAHIRO, HATAMURA YOTARO, ICHIKI KATSUNORI, KAJIYAMA MASAAKI, KATO TAKAO, NAKAO MASAYUKI, TSUZUKI TAKASHI, HATAKEYAMA, MASAHIRO, HATAMURA, YOTARO, ICHIKI, KATSUNORI, KAJIYAMA, MASAAKI, KATO, TAKAO, NAKAO, MASAYUKI, TSUZUKI, TAKASHI
Applicants: EBARA CORP, HATAMURA YOTARO, EBARA CORPORATION, HATAMURA, YOTARO
Application year: 1996
Main classification: H01J37
IPC codes: H01J37