Patent Application
20230395353
The present invention relates generally to process apparatuses having differential pumping devices.
There is known a process apparatus which works to scan the surface of a specimen with a focused ion beam emitted from a focused ion beam column, capture secondary particles (e.g., secondary electrons, secondary ions) sputtered from the surface of the specimen which the focused ion beam bombards, and then provide a scanning ion microscopic image for use in observation of the surface of the specimen or formation of a film on the surface of the specimen. Specifically, the process apparatus is designed to have several functions, such as specimen observation, etching (sputtering), and chemical vapor deposition (CVD).
The above type of process apparatus is capable of emitting a focused ion beam to a required portion of the surface of a repair-required substrate using information derived from the scanning ion microscopic image and simultaneously delivering a CVD gas to the required portion from a supply nozzle arranged outside the focused ion beam column to locally form a thin film for processing or repairing the required portion.
In recent years, a process apparatus has been proposed which is equipped with a local exhaust ventilation system which works to locally create a vacuum space on the surface of a repair-required substrate without need of a large-sized vacuum chamber (see, for example, Patent Literature 1). The process apparatus is designed to have formed therein a precursor gas path which supplies a precursor gas directly to below an orifice in a head (i.e., a lower end) of a focused ion beam column (see FIG. 4 of Patent Literature 1).
The above known process apparatus, however, faces a problem that it is difficult for the precursor gas directly supplied to the head of the focused ion beam column to reach the surface of the substrate to be processed, which leads to instability in forming a film on the surface of the substrate using CVD techniques.
The present invention was made in view of the above-mentioned problem. It is an object of the present invention to provide a process apparatus that is capable of forming a film on a substrate with high accuracy.
In order to solve the above-described problem and achieve the object, the present invention is to provide a process apparatus which comprises: (a) a differential pumping device including a head which faces a given area of a process surface of a substrate to be processed and has a plurality of annular grooves formed in a process surface-facing surface of the head which faces the process surface of the substrate, the annular grooves surrounding the center of the head, the head having an orifice which is formed inside an innermost one of the annular grooves and defines a processing space serving to achieve processing of the process surface, at least one of the annular grooves being connected to a vacuum pump to suck gas from the one of the annular grooves with the process surface-facing surface opposed to the process surface to create a high-level vacuum in the processing space; and (b) a focused ion beam column which is arranged on an opposite side of the head to the process surface-facing surface and includes a chamber leading to the orifice to be communicable with the processing space, the focused ion beam column also including a focused ion beam optical system which is disposed in the chamber and works to emit a focused ion beam through the orifice. A precursor gas supply is connected to the innermost one of the annular grooves to eject a precursor gas toward the process surface so that the precursor gas flows into the processing space along the process surface.
It is preferable in the above mode that the head includes a head body and a groove-forming plate attached to a surface of the head body which faces the substrate to be processed, and the surface of the groove-defining plate which faces the substrate to be processed is the process surface-facing surface.
It is also preferable in the above mode that the groove-defining plate is arranged in the form of islands within an outline of the surface of the head body which faces the substrate to be processed, and a shoulder of the head which is defined by the surface of the head body which faces the substrate and an outer periphery of the groove-defining plate is in a tapered shape.
Alternatively, it is preferable in the above mode that the groove-defining plate is arranged in the form of islands within an outline of the surface of the head body which faces the substrate to be processed, and a shoulder of the head which is defined by the surface of the head body which faces the substrate and an outer periphery of the groove-defining plate is shaped to have a rounded surface.
It is also preferable in the above mode that the groove-defining plate includes a plurality of annular plates arranged around the center of the head.
It is also preferable in the above mode that a microchannel plate is disposed which has a beam output orifice which is formed in a nose of the chamber and through which the focused ion beam passes. The microchannel plate has a portion which lies around the beam output orifice and serves as a detector to capture secondary charged particles sputtered from the substrate.
It is also preferable in the above mode that an optical microscope is also provided which detects an alignment mark formed on the substrate.
It is also preferable in the above mode that an observation microscope is also provided which is arranged at a given offset-distance away from the head and works to observe a given region of the substrate to be processed.
It is also preferable in the above mode that the focused ion beam column includes a plurality of focused ion beam columns each of which has the differential pumping device mounted on a nose thereof, each of the focused ion beam columns being arranged to face a respective one of a plurality of regions defined on the process surface of the substrate.
It is also preferable in the above mode that the focused ion beam column equipped with the differential pumping device is arranged to be movable in X- and Y-directions relative to the substrate which is fixed.
The present invention is capable of realizing a process apparatus which is configured to ensure the stability in performing a film-forming operation on a substrate.
Process apparatuses according to embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the drawings are schematic, so that the dimension, ratio, number, and shape of each element differ from those of the real element. In addition, there are parts or portions in which the dimensional relationship, ratio, and shape are different among the drawings.
The configuration of the differential pumping device 2 will be described below with reference to
The head 7 is composed of two disc-shaped metal plates which are much smaller in area than the process surface 6A of the photomask 6 to be processed. The substrate support 4 is moveable in “X” and “Y” direction to orient the head 7 to face any area of the process surface 6A to be processed.
As shown in
As shown in
The cylindrical chamber 14 of the FIB column 3, which will be described later, is, as illustrated in
At least one (three in this embodiment) of the annular grooves 10A, 10B, 10C, and 10D, e.g., the annular grooves 10B, 10C, and 10D are connected to the connecting pipes 12B, 12C, and 12D through the communication paths formed inside the head body 8. The connecting pipes 12B, 12C, and 12D are connected to a vacuum pump (not shown).
The innermost annular groove 10A is connected to a precursor gas supply, not shown, which is a supply source of a deposition gas (e.g., a precursor gas or a CVD gas) through the connecting pipe 12A. When the process surface-facing surface 9A of the head 7 is oriented to face the process surface 6A to be processed, the head 7 is capable of functioning to suck air from the annular grooves 10B, 10C, and 10D to create a high vacuum within the processing space Sp. The head 7 also ensures a reliable supply of the precursor gas to the processing space Sp, which is highly vacuumized in the above manner, from the innermost annular groove 10A to achieve CVD formation of a film on the process surface 6A to be processed which faces the orifice 11.
Incidentally, a conventional process apparatus is designed to have an outlet of a precursor gas path in a local exhaust ventilation system which is arranged adjacent to an orifice in a head of a chamber of a focused ion beam column and thus encounters a problem that a CVD-produced material is easy to deposit on the wall near the outlet of the precursor gas path. Specifically, the CVD-produced material deposits near the head of the chamber, so it might have a negative influence on the focused ion beam. In order to get rid of such negative influence, the local exhaust ventilation system requires maintenance in the conventional process apparatus. In the actual field, it is necessary to frequently clean the deposited CVD-produced materials following the removal of the local exhaust ventilation system from the focused ion beam column. This leads to an issue that it takes personnel a long time to detach, clean, and install the exhaust ventilation system because the local exhaust ventilation system has exhaust pipes and precursor gas supply pipes connected thereto.
In the conventional process apparatus, since the gap between the local exhaust ventilation system and the substrate to be repaired is as narrow as about 40 μm, there is a possibility that the lower surface of the local exhaust ventilation system may contact the substrate to be repaired and need to be replaced. Even in such replacement, there is a problem that it takes a long time and a lot of management cost.
The FIB column 3 is disposed on a surface (i.e., an upper surface) of the head 7 which faces away from the process surface-facing surface 9A of the head 7 and has a top opening communicating with the orifice 8B and 11 of the head 7.
The FIB column 3 includes the chamber 14 communicating with the processing space Sp and the focused ion beam optical system 15 built in the chamber 14. The FIB column 3 is configured to emit the focused ion beam Ib from the top thereof. The focused ion beam Ib passes through the orifice 11. The FIB column 3 is supported by the support frame 5 in a suspended state.
The focused ion beam system 15 includes an ion source which generates the ion beam Ib, an electrostatic condenser lens which collimates the ion beam Ib, an electric field deflector which steers or scans the ion beam Ib, an objective electrostatic lens which focuses the ion beam Ib. The ion source is implemented by a gallium (Ga) ion source, but, noble gas ion source, using an inductively coupled plasma (ICP) with noble gas like argon (Ar) or gas electrolytic ionization, may be used. Field lenses are good as the lenses for the ion beam Ib.
Tungsten hexacarbonyl (W(CO)6) may be used as a deposition gas for CVD. When the focused ion beam is emitted to the tungsten hexacarbonyl W(CO)6 near a substrate, it will cause the tungsten hexacarbonyl W(CO)6 to be decomposed into W and CO, leading to deposition of W on the substrate.
In a processing operation of the process apparatus 1 in this embodiment, the process surface 6A of the photomask 6 is first placed to face the process surface-facing surface 9A of the head 7 and extend parallel to the process surface-facing surface 9A with a predetermined gap therebetween.
Subsequently, a vacuum pump (not shown) is activated to suck air from the three annular grooves 10B, 10C and 10D through the connecting pipes 12B, 12C, and 12D. This causes the processing space Sp defined by the orifice 11 arranged inside the innermost annular groove 10A to be evacuated to a high vacuum due to the suction action through the annular grooves 10B, 10C, and 10D.
In the state of a high vacuum created within the processing space Sp, a precursor gas (i.e., gas for CVD) is supplied to the innermost annular groove 10A through the connecting pipe 12A from a precursor gas supply (not shown). The innermost annular groove 10A is in the vicinity of the processing space Sp, and so the precursor gas reaches the processing space Sp without any fail. The precursor gas moves along the process surface 6A of the photomask 6 toward the processing space Sp until it lies underneath the processing space Sp. In other words, the precursor gas exists stably in the area where the film is to be formed.
In the above state, when the FIB column 3 emits the ion beam Ib toward the processing space Sp, it causes the thin film to be formed by the CVD techniques on the area of the process surface 6A which faces the orifice 11.
In the process apparatus 1 according to the present embodiment, the differential pumping device 2 is capable of locally creating a high vacuum, thereby eliminating the need to place the whole of the process surface 6A of the photomask 6 in a vacuum.
In the differential pumping device 2 of this embodiment, the precursor gas supply is connected to the innermost annular groove 10A. By discharging the precursor gas from the innermost annular groove 10A toward the process surface 6A of the photomask 6, the precursor gas reaches the processing space Sp from the orifice 11 through the process surface 6A to be processed. This ensures the stability of the precursor gas to reach the area of the process surface 6A which is exposed to the processing space Sp to form a thin film of excellent quality by focused ion beam Ib using the CVD techniques.
Moreover, in this embodiment, the groove-defining plate 9 is easily detachable from the head body 8 and replaceable with a new one, making it unnecessary to detach the FIB column 3 and the connecting pipes 12A, 12B, 12C, and 12D, making the maintenance easy.
The process apparatus 1A shown in
When the gap between the process surface-facing surface 9A of the differential pumping device 2 and the process surface 6A of the photomask 6 is selected to be as small as about 40 μm, it may cause a turbulence flow to be created in the gap which triggers the occurrence of vibrations. In the modification 1, the outer periphery of the groove-defining plate 9 is shaped to have the tapered surface 9B with no sharp shoulder, thereby minimizing the risk of occurrence of the turbulence flow and thus reducing the occurrence of vibrations.
In the modification 2, the outer shoulder of the groove-defining plate 9 is shaped to have the rounded surface 9C which, like the modification 1, alleviates the risk of occurrence of a turbulence flow between the process surface-facing surface 9A and the process surface 6A to reduce the mechanical vibration of the process apparatus 1B. The modification 2 is identical in operation of the process apparatus 1B with the first embodiment and offers substantially the same beneficial advantages as those derived by the process apparatus 1 in the first embodiment.
The modification 3 is capable of slightly altering the thickness of each of the annular plates 9D, 9E, 9F, 9G, and 9H of the groove-defining plate 9 to regulate the differential pumping operation and also enables only damaged one or more of the annular plates 9D, 9E, 9F, 9G, and 9H to be replaced with a new one(s). This results in a decrease in maintenance cost and facilitates the ease of removal or replacement of each of the annular plates 9D, 9E, 9F, 9G, and 9H.
The air float pad 16 ejects inert gas to the process surface 6A to be processed to create a gaseous curtain. This causes the air float pad 26 to bias the head 9 away from the process surface 6A. The use of inert gas in this way enables the inside of the chamber 14 to be purged with the inert gas, which contributes to reduction in particles or other contaminations. The ejection of inert gas on the process surface 6A also cancels the vacuum pressure arising from the differential pumping operation.
When it is required to observe the process surface 6A of the photomask using the process apparatus 1F, the focused ion beam Ib is emitted while suspending the supply of deposition gas (i.e., precursor gas). The focus ion beam Ib then passes through the ion beam output orifice 17A and bombards the process surface 6A to be processed. This causes secondary charged particles P sputtered from the process surface 6A to enter the detector 17B to create electrons. The electrons generated in this way may be amplified using avalanche current to derive information about the condition of the process surface 6A. The process apparatus 1F in this embodiment is, therefore, capable of measuring the condition of the process surface 6A with a high sensitivity.
The process apparatus 1F according to this embodiment is capable of shortening the working distance (WD) of the objective electrostatic lens 15A, thereby improving the efficiency in capturing the secondary charged particle P as compared to the conventional method for detecting secondary charged particles with a scintillator which is arranged away from a focused ion beam optical system within a vacuum chamber.
If the working distance of the objective electrostatic lens 15A to the substrate 8 is too short, it becomes more difficult to place a structural element, such as a deposition gas (precursor gas) nozzle, near the tip of the chamber 14. In this embodiment, however, the annular groove 10A works to discharge deposition gas to an area of the process surface 6A located near the orifice 11, thereby directing the deposition gas to the processing space Sp through the process surface 6A to be processed. This embodiment is, therefore, free from the problem that the deposition gas supply becomes difficult if the working distance is shortened. This embodiment ensures high-quality and stable deposition with CVD because the precursor gas reaches the area of the process surface 6A which faces the processing space Sp without fail.
This embodiment, as described above, shortens the working distance of the objective electrostatic lens 15A, thereby improving the focusing efficiency of the focused ion beam optical system 15, which enables the focused ion beam optical system 15 to emit a finely focused ion beam Ib.
Further, this embodiment makes it unnecessary to alter the position of the photomask 6 because the positions of the photomask 6 in the observation mode for observing the condition of the process surface 6A and in the deposition mode for forming a film with CVD are the same. This eliminates a risk that the position of an area to be processed may shift undesirably as the photomask 6 moves.
The support frame 20 is, as shown in
The vacuum pump 27 is connected to the FIB column 3. The vacuum pump control power supply 28 is connected to the vacuum pump 27. The stage control power supply 29 is connected to the XY precision stage 25.
Particularly, this embodiment has the optical alignment microscopes 30 each of which is located above a respective one of the alignment marks 6B arranged on four corners of the photomask 6 placed at a given position on the XY precision stage 25.
According to this embodiment, the alignment microscopes are easy to install because the differential pumping device 2 has realized a localized vacuum space, and so the pressure outside the area to be processed is the atmospheric pressure. This embodiment is capable of achieving alignment of the photomask 6 with the optical alignment microscopes 30 using the alignment marks 6B on the four corners of the photomask 6 to determine coordinates of the photomask 6 based on a relative relationship of the positions of the optical alignment microscopes 30 with a location where the processing is conducted by the FIB column 3.
For the foregoing reasons, the process apparatus 1G according to this embodiment makes it unnecessary to move the XY precision stage 25 for the alignment. Moreover, the process apparatus 1G is effective in reducing the amount of positioning time for the alignment.
In the conventional process apparatus, secondary electrons or secondary ions sputtered from a photomask irradiated with a focused ion beam are captured by a charged-particle detector arranged outside the FIB column. Changes in intensity of the secondary electrons or secondary ions are used to observe the surface configuration of a process-required substrate in the form of ion images. Usually, the ion images are used to check an ion beam-emitting location. The secondary charged particles, however, depend upon the surface configuration (i.e., angle of inclination) of the process-required substrate, so that only the surface configuration is detected in the form of ion images. For this reason, in a case of the surface configuration with less irregularities, ion images with low contrast will be generated, which may result in a difficulty in confirming the ion beam-emitting location, which leads to a drop in positioning accuracy.
The process apparatus 1H according to this embodiment is, as illustrated in
By determining the offset of the ion beam-emitting location from the position of the photomask 6 derived by the optical microscope 31 in advance, the photomask 6 may be placed at the ion beam-emitting location immediately after the position of a process-required area of the photomask 6 is calculated using an optical image of the process-required area. As apparent from the above discussion, this embodiment is capable of determining the ion beam-emitting location even when the surface of the photomask 6 has less irregularities.
Each of the FIB columns 3 is coupled to the vacuum pump 27 to which the vacuum pump control power supply 28 is connected. The stage control power supply 29 is connected to the XY precision stage 25.
In particular, this embodiment has the four FIB columns 3 each of which is aligned with a respective one of four regions defined on the photomask 6. Use of the single FIB column 3 for the single photomask 6 requires movement of the substrate support 4 by a distance of four times an area of the substrate (i.e., the photomask 6). In contrast, this embodiment has the four FIB columns 3, thereby resulting in a decrease in distance the substrate support 4 is required to be moved by the XY precision stage 25, which leads to a decrease in footprint of the process apparatus 1I.
The XY gantry stage 33 is, as shown in
The FIB column 3 is connected to the vacuum pump 27. The moving block 34 is connected to the stage control power supply 35.
This embodiment, as described above, has the moving block 34 which is secured to the gantry stage 33 to be movable in the X- and Y-directions, thereby enabling the FIB column 3 and the optical alignment microscope 30 mounted on the moving block 34 to be moved without need to move the photomask 6. It is, therefore, possible to decrease the footprint of the process apparatus 1J.
Although each of the embodiments according to the present invention has been described, the present invention contributes to improvement in quality of processing conducted in the processing space Sp because a high-level vacuum in the processing space Sp is maintained without fail. Further, the precursor gas is discharged from the innermost annular groove 10A surrounding the orifice 11 within the process surface-facing surface 9A of the head 7, and so, thin film is formed on the photomask 6 without fail.
The present invention provides easy maintenance and reduces equipment cost and management cost because the groove-defining plate 9 is detachably attached to the head 7, and so, what is required is only replacement or cleaning of the groove-defining plate 9.
Although the embodiments of the present invention have been described, the description and drawings, which is a part of the disclosure of these embodiments, should not be understood to limit the present invention. From this disclosure, alternative embodiments, examples, and operational technology should be clear to a person skilled in the art.
In the foregoing embodiments, the number of the annular grooves formed in the differential pumping device is not limited to four, but however, at least two annular grooves: one being a gas discharge groove and the other being a gas ejecting groove, may be provided. Additionally, the annular grooves 10A, 10B, 10C, and 10D are circular in shape, but however, may alternatively be designed in any other shape, such as a square looped shape.
In the foregoing embodiments, the photomask 6 is used as a substrate to be processed, but the present invention is applicable to various kinds of display substrates that require processing for thin film formation following observation of wiring defects.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-111960 | Jun 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/020647 | 5/31/2021 | WO |
