JP2010135351A - Suction type local microplasma etching apparatus with microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suction type local microplasma etching apparatus with a microscope, and to provide a local microplasma etching method. <P>SOLUTION: The suction type local microplasma etching apparatus includes a sample plate, a vacuum container to which a gas introducing part is provided, a plasma gun with a capillary pipe and an RF microwave oscillation electrode, a microscope, and a sample stage with the sample plate. The sample stage is present in the vacuum container. The tip of the capillary pipe is protruded into the vacuum container. A rear end is present outside the vacuum container and is connected to an exhaust device. The head of the microscope is protruded in the vacuum container, and reactive material gas for plasma introduced in the vacuum container from the gas introducing part is sucked through the tip of the capillary pipe. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a suction-type local microplasma etching apparatus with a microscope that performs operations such as peeling and removal of an insulating film (SiO ₂ ) or the like of a device wafer in a local region.

  The plasma etching referred to in the present invention refers to an action of removing an etching portion of an object to be etched (hereinafter abbreviated as a workpiece) by a plasma reactive gas. For example, plasma reactive gas such as fluorine is used as a workpiece. It is characterized in that the irradiated work surface is etched and removed with high accuracy by irradiating the surface and evaporating a volatile compound produced by the reaction between the reactive gas and the work. The effect of the action by plasma etching differs depending on the type of reactive gas used, and the strength and weakness can be controlled by adjusting the time and applied voltage, so that it can also be used as a method for flattening. Further, in the case of microetching work such as local peeling, removal, punching, punching, etc. on a minute portion of a device wafer or silicon bare wafer, a microplasma etching apparatus equipped with a plasma gun is used.

  Conventionally, a plasma gun-mounted microplasma etching apparatus introduces a reactive source gas such as carbon tetrafluoride into a capillary made of quartz or glass having a plasma generation region, and RF (radio frequency) Microwave is irradiated from the electrode for microwave oscillation (hereinafter abbreviated as RF electrode), the reactive material gas is excited to become plasma, and the generated plasma gas is injected from the plasma gun onto the work surface by the downstream method. This is an apparatus for etching a minute portion, and a so-called injection type plasma gun is used. One feature of the etching method using this apparatus is that the operation is performed in a non-contact manner. In the field of semiconductors, it is applied as means for locally peeling, removing, punching, punching, or the like of minute portions, or as means for flattening by removing irregularities on the surface of a semiconductor wafer. The object to be etched has an extremely wide range of application not only to metals or metal oxides but also to organic substances such as resins by changing the reactive source gas.

  In recent years, semiconductor devices have been increasingly diversified in recent years, and are beginning to be used in fields that have not been used so far, and the trend is expected to continue to expand in the future. At the same time, as the device itself can be seen in ULSI (Ultra-Large Scale Integration), the number of highly integrated and multi-layered devices has increased, the circuit line width has become increasingly finer, and the manufacturing process has become more complex. Therefore, high precision and multi-layering have been demanded. Specifically, in the next generation device, the circuit width is set to several tens of nm, and the interval between wirings is set to 35 nm. Under such circumstances, in order to perform work such as separation and removal of the insulating film in a minute local region for the purpose of failure analysis of semiconductor devices and semiconductor integrated circuit products, the above-described jet type plasma gun mounted type A plasma etching apparatus has been used.

  However, in the situation of the above-mentioned diversification of technologies and the progress of finer processing, when a plasma etching apparatus equipped with a conventional plasma gun with a conventional structure is used for such a purpose, the workpiece is directly heated to a high temperature. As a result, it has been pointed out that there are problems such as causing thermal damage, worsening the surface roughness, and excessive molecules (for example, carbon) adhering to the workpiece surface and reducing the etching rate. Furthermore, when performing plasma etching on the same part for a long time for the purpose of drilling, drilling, etc., in order to remove the aforementioned adhered and deposited foreign matter, the work is temporarily stopped, and the foreign matter removal using, for example, oxygen gas is performed. It has been pointed out that it is necessary to perform another plasma etching process for the above. Furthermore, unnecessary heating is performed, the surroundings are damaged, the work is inaccurate and contaminated, and the plasma diffusion phenomenon at the gap between the capillary tube tip and the workpiece causes the expected phenomenon. It has been pointed out that there is a problem that etching is performed with a hole diameter larger than the hole diameter, or the precision of the shape of the hole is lacked, that is, the accuracy of the required work cannot be followed. It has also been pointed out that it is difficult to form extremely fine holes of 900 μm or less, and that it cannot follow the above-mentioned diversification and refinement of technology. In other words, there is an urgent need to localize and refine the etching area in the microplasma etching operation.

  Furthermore, when performing plasma etching work in a local area, it is important to determine the part to be etched of the workpiece and the positioning work that accompanies it. In addition, confirmation and addition of the etching effect by observation of the work surface before and after the etching work. Alternatively, it is an important factor to confirm the necessity of etching work for correction.

  Regarding the use of the plasma etching apparatus as a method and apparatus for locally etching the surface of a silicon wafer or the like, for example, as described in Patent Document 1, means for performing local plasma etching, and a plasma reaction An apparatus including an exhaust pipe for discharging a reaction product of the etching gas and the object to be etched and a vacuum pump can be given. In addition, regarding the method and apparatus for performing the local etching and flattening, the flatness of the portion to be etched is measured in advance, the two-dimensional distribution data of the flatness is processed, and then the etching is performed. For example, Patent Document 2 discloses a method of flattening the entire workpiece while enlarging in the direction and scanning the workpiece in the XY axis direction. All of these methods are techniques related to planarization of the surface of a silicon wafer or the like by plasma etching, and are techniques aimed at improving so-called flatness, improving productivity, and reducing the defect rate.

  Patent Document 3 describes a plasma etching apparatus designed to accurately confine plasma in a plasma etching in a local region and supply a reactive gas only to the surface requiring etching of a substrate. This apparatus is intended to prevent plasma diffusion, and does not prevent adverse effects such as high-temperature gas diffusion, thermal damage in the surrounding area, or accumulation of foreign substances.

  Patent Document 4 describes a micromanipulation apparatus that performs local peeling, perforation, removal, etc. of an insulating film of a multilayer integrated semiconductor device by a local plasma mechanism under a microscope for the purpose of analyzing the cause of failure. However, it is a technique for performing local plasma etching work while controlling it under microscopic observation by micromanipulation, which is mechanically complicated and unsuitable for simple work. In addition, since it uses an injection type plasma gun, damage and contamination of the surrounding area due to the influence of high temperature plasma gas, as well as adverse effects on the precision of shapes such as peeling and perforation due to plasma diffusion. The problem was not complete. In order to perform etching with a plasma gun and observation with a microscope at the same time in the same field of view, the direction of the plasma gun and the direction of the microscope's field of view must be obliquely crossed. there were. Furthermore, the problem of the complexity of work, such as the removal work of a deposit accompanying continuing work for a long time, has not been solved yet.

The above-mentioned technology applies the strong removal capability of the reactive gas that has been converted into plasma in the plasma generator, but this technology requires the supply of a special source gas (such as carbon tetrafluoride) first. Then, next, a plasma gun equipped with a reaction tube (capillary) and an RF electrode, a vacuum vessel, and the like are necessary, and a suction device for removing the reaction gas and the generated evaporated gas is also necessary. And, for the purpose of failure analysis of semiconductor device wafers and semiconductor integrated circuit products, silicon bare wafer surface processing, etc., operations such as exfoliation and removal of the SiO ₂ insulating film in the local region are performed, so the work accuracy is The requirement for the fineness of the shape of the etched hole is particularly severe, and it must be a structure that minimizes the influence on other peripheral portions.

That is, as described above, the conventional microplasma etching apparatus irradiates and irradiates a reactive gas that has been converted to plasma on the surface of the workpiece, and removes or removes the microlocal portion. It has problems such as diffusion of high temperature gas, adhesion and contamination of foreign matter, contamination of the surface of the work other than the local area by the reaction gas or evaporating gas and the inside of the container, and the size of the part that has been peeled off or removed, especially Neither the correspondence to minute parts nor the accuracy of the shape was sufficient. Furthermore, there was no means for determining in real time whether or not to determine the part to be etched of the workpiece, positioning for that, observation of the workpiece surface before and after the etching operation, and the necessity of addition or correction work.
JP-A-10-147893 JP 2000-174004 A JP-A-5-347277 JP 2008-46324 A

  In view of the above-mentioned problems, the present inventors have conducted intensive studies, and in the vacuum vessel in which the reactive source gas exists, the tip of the capillary tube of the plasma gun equipped with the capillary tube and the RF electrode is placed on the sample stage. It has been found that plasma is generated in the vicinity of the work surface when suction is performed from the tip of the capillary tube while a voltage is applied from the RF electrode. By applying this phenomenon, the above-mentioned problems have been solved, and further, by fixing the microscope head in the vacuum vessel, it is easy to determine the position of the workpiece to be etched and to position it. Furthermore, it is possible to avoid the trouble of observing the workpiece surface before and after the etching operation, determining whether or not to add or modify the etching operation, and determining by another inspection means after removing the workpiece. The purpose of the present invention is to provide a suction type local microplasma etching apparatus with a microscope for performing accurate and precise etching in a local region and effectively performing operations such as peeling and removal of an insulating film. Furthermore, another object of the present invention is to provide a microplasma etching method using the suction type local microplasma etching apparatus with a microscope.

  The first aspect of the present invention described above includes a sample stage, a vacuum vessel provided with a gas introduction unit, a plasma tube including a capillary tube and an RF microwave oscillation electrode, a microscope, and a sample stage. A suction type local microplasma etching apparatus having a sample stage, wherein the sample stage is in a vacuum vessel, the tip of the capillary tube is protruded in the vacuum vessel, and the rear end is outside the vacuum vessel Exhaust device is connected and the microscope head is protruded in the vacuum vessel, and the reactive material gas for plasma introduced into the vacuum vessel from the gas inlet is sucked from the tip of the capillary tube This is a suction type local microplasma etching apparatus with a microscope. The sample stage has a sample stage on which an object to be etched is placed, movement of the sample stage in the X-axis, Y-axis, and Z-axis directions and rotation around the Z-axis in any direction, A driving device that tilts at an angle is provided, and the sample stage is placed on a base at the bottom of the vacuum vessel, and the base on which the sample stage is placed can move in the Z-axis direction.

  In the present invention, the flow of the reactive source gas is sucked into the capillary tube through a narrow gap formed between the workpiece surface and the capillary tube tip, and the reaction is performed by the RF electrode installed so as to surround the capillary tube. The source gas is excited and plasma is generated near the work surface in opposition to the gas flow. Such a phenomenon is more likely to occur when the position of the RF electrode is placed closer to the tip of the capillary tube, that is, the opening at the tip of the capillary tube than the plasma gun used in the conventional jet plasma etching. And since the plasma tends to escape toward the vacuum vessel, it is possible to inactivate the escaped plasma by bringing the workpiece as close as possible to the opening at the tip of the capillary tube, thereby suppressing the adverse effect on the peripheral portion of the etching point. it can. Therefore, the gap between the opening at the tip of the capillary tube and the workpiece is preferably short, specifically 500 μm or less, more preferably about 100 μm or less. If this range is exceeded, stable plasma cannot be generated.

  The second gist of the present invention is that, in the above-described suction type local microplasma etching apparatus with a microscope, the vacuum vessel is depressurized by operating the exhaust device, and a necessary amount of the reactive source gas is placed in the vacuum vessel in a vacuum state. Is introduced from the reactive source gas supply unit, the workpiece placed on the sample stage is placed under the observation microscope barrel, and the processing point on the workpiece is positioned, and then the sample stage is placed on the sample stage. The workpiece surface is moved so that the processing point of the workpiece placed on the workpiece is located below the tip of the capillary tube of the plasma gun, and in this state, a voltage is applied to the RF electrode to excite the reactive source gas and thereby the workpiece surface. Plasma etching is performed by generating plasma at the machining point and etching the workpiece surface with the generated plasma while suctioning with an exhaust device connected to the plasma gun. After engineering was completed, the sample stage is moved under the original observation microscope lens barrel, a micro plasma etching method characterized by performing the observation of the machining state of the workpiece by the observation microscope lens barrel.

  The pressure in the vacuum vessel and the cavitation tube during the actual etching operation needs to be lower than the internal pressure of the vacuum vessel in order to perform the suction. In general, it is preferable to set the former to about 10 to 500 Pascal (hereinafter abbreviated as Pa) and the latter to about 0.01 to 100 Pa, although it depends on the hole diameter of the opening at the tip of the capillary tube. In addition, about the pressure in a cabinetry pipe | tube, it is the numerical value (plasma gun exhaust_gas | exhaustion part pressure) measured with the vacuum gauge attached to the exhaust apparatus connected with a cavity pipe | tube. Stable plasma can be generated on the surface of the workpiece by setting the state as described above. It is preferable that a reactive source gas is continuously introduced from the reactive source gas supply unit even during the etching operation, and the internal pressure inside the vacuum vessel is kept constant within the above range so that a stable plasma etching action can be achieved.

  The suction-type local microplasma etching apparatus with a microscope according to the present invention is an apparatus equipped with a suction-type local plasma gun and an observation microscope, whereby plasma etching in a local region can be performed easily, quickly and efficiently. In addition, it is possible to avoid the adverse effects of deposits adhering to the etched surface, contamination of surfaces other than the etched surface, and thermal damage caused by high heat gas. . In addition, compared to conventional plasma plasma gun mounted microplasma etching equipment, it is possible to etch with smaller hole diameters, and the purpose is to analyze defects in semiconductor devices and semiconductor integrated circuit products that are becoming increasingly integrated and multi-layered. Thus, it is an extremely effective apparatus for work such as peeling and removal of the insulating film in a minute local region.

  In the suction type local microplasma etching apparatus with a microscope of the present invention, the sample stage includes a sample stage on which a workpiece is placed, movement of the sample stage in the X-axis, Y-axis, and Z-axis directions, and a Z-axis as a center. The drive mechanism that performs the rotation (θ axis) is configured to tilt at an arbitrary direction and angle. The above-described drive mechanism of the sample stage in the X-axis, Y-axis, and Z-axis directions is for accurately positioning a processing point on the workpiece, and can perform coarse movement and fine movement in each axis direction. It is preferable. Here, coarse movement means movement on the order of μm, fine movement means movement on the order of nm, rough positioning is performed by coarse movement, and then precise positioning is performed by fine movement.

  The driving means is not particularly limited. For example, known means such as a micromotor, an ultrasonic motor, a fine screw, and a piezo element can be appropriately used as the actuator, but the piezo element is particularly preferable as the fine movement means. . The coarse movement and the fine movement in the same axial direction are performed by different drive mechanisms, respectively, but driving means capable of performing both the coarse movement and the fine movement, for example, an ultrasonic motor with a built-in piezoelectric element, etc. It may be used. As a result, even when a workpiece having a large surface area, such as a silicon wafer, is used, the rough positioning device is first driven to perform rough positioning, and then the fine motion device is driven to achieve accurate positioning quickly. And it can be done reliably.

  Since the above-described suction type plasma gun and observation microscope are fixed in the apparatus, the distance between the tip of the capillary tube of the suction type plasma gun and the tip of the observation microscope head is constant. There is no change. An axis connecting these two points is set as an X axis, and the sample stage has a structure that can freely move between two fixed points on the X axis. The movement of the sample stage between two fixed points is not performed by using the driving mechanism that performs the coarse and fine movements of the sample stage as described above, but by using a separately provided driving mechanism. It is preferable to adopt a structure that can be moved automatically.

  Since the above-described positioning operation determines the operation point for performing the plasma etching processing, in the apparatus of the present invention, it is performed at the focal position directly under the head of the observation microscope. Since the field-of-view range is naturally different between when the coarse motion device is driven and when the fine motion device is driven, the magnification of the microscope may be changed when switching from coarse motion to fine motion. The observation microscope to be used is not particularly limited, but a normal optical microscope, laser microscope, scanning electron microscope (hereinafter abbreviated as SEM) or the like can be used. Is preferably used. When the SEM is used as an observation microscope, the processing point of the workpiece is positioned with the SEM, and then the sample stage is moved to perform plasma etching, but during that time, the SEM stops functioning. After the plasma etching process is completed, the plasma is stopped, the sample stage is moved again, and the SEM is operated to observe and evaluate the processed part. As a result, it is possible to avoid the complexity of removing the workpiece from the apparatus and observing and evaluating the machining location with the external apparatus.

  The apparatus of the present invention cannot be performed while simultaneously observing the state of the etching process. For example, if the work of moving and observing the workpiece under the microscope head is repeated every time the etching process is performed for a certain time, the real time It is possible to observe in a state close to that, and it is also possible to take a frame-feed photo. Since the plasma gun and the microscope head are vertically arranged side by side, the etching process direction and the microscopic observation direction are exactly the same, and there is no inconvenience that the etching process state is observed from an oblique direction.

  In the suction type local microplasma etching apparatus with a microscope of the present invention, a suction type plasma gun is used. As described above, a stable plasma is generated when the gap between the opening at the tip of the capillary tube and the work is short. Therefore, specifically, it is about 500 μm or less, more preferably 100 μm or less, and if it is out of this range, stable plasma generation cannot be performed. Therefore, the adjustment of this gap is extremely important. However, when moving from the microscope head position to the plasma gun position while holding such an extremely short gap, the work surface and the tip of the capillary tube may come into contact with each other, causing a risk of crashing. It is effective to separately provide a large coarse movement mechanism that moves up and down in the Z-axis direction in mm units. This large coarse movement mechanism may be manual.

  The suction type local microplasma etching apparatus with a microscope of the present invention can be provided with additional equipment in addition to the microscope head. For example, an energy dispersive X-ray analyzer (EDX) can be provided to perform a composition analysis of processing points in real time. By providing a viewing window at the vacuum vessel position corresponding to the plasma gun tip position and disposing the EDX detector there, for example, the removal of the oxide film such as silicon oxide can be accurately caught and the inner layer that is not subject to etching Excessive etching into the (silicon layer) can be prevented. In other words, it is possible to set so that the end point of etching is automatically detected. Further, for the purpose of plasma detection, a spectrophotometer can be provided in the same manner to automate stabilization of plasma generation, or an infrared laser sensor can be provided and controlled while detecting the etching depth. Of course, it is also possible to automate the etching process by integrating and controlling these main facilities and additional facilities using a computer.

  With these additional equipment, volatile compounds and other by-products (for example, carbon) generated by the reaction between the reactive gas and the workpiece do not enter the vacuum vessel during the etching operation, and the inside of the vessel is always in the interior. It becomes possible for the first time in the suction type local microplasma etching apparatus of the present invention characterized by being clear. When an injection-type plasma gun is used, not only the above-mentioned volatile compounds coexist in the atmosphere in the vacuum vessel, but also the inside of the vessel is gradually contaminated by volatile compounds and by-products such as carbon. However, it may be difficult to install these analyzers together.

  Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view of a suction type local microplasma etching apparatus with a microscope equipped with a suction type plasma gun of the present invention. FIG. 2 is an explanatory view of a suction type plasma gun of the present invention, and FIG. 3 is an explanatory view showing a sample stage of the present invention. FIG. 4 is a diagram showing an example of a local plasma etching method using the suction type local microplasma etching apparatus with a microscope according to the present invention, and FIG. 5 is a suction type with a microscope according to the present invention equipped with auxiliary equipment and the like. It is a completion image figure which shows an example of a local microplasma etching apparatus.

  In FIG. 1, 1 is a vacuum vessel, 4 is a microscope, 5 is a suction type plasma gun, and 14 is a sample stage. That is, the head of the microscope 4 and the suction-type plasma gun 5 are projected in the vacuum container 1. A sample stage 14 is housed inside the vacuum container 1, and the sample stage 14 is placed on the base 13. The vacuum vessel 1 is provided with a gas introduction unit 3 connected to a reactive source gas supply unit 2, and has a structure in which a reactive source gas is supplied from the gas introduction unit 3. The rear end portion 11 of the suction type plasma gun 5 that is not on the vacuum vessel side is connected to an exhaust device 12, thereby evacuating the vacuum vessel and suctioning the reactive source gas.

  In order to shorten the time required for starting up the apparatus, a separate exhaust device can be provided in the vacuum vessel. For the same purpose, a reactive raw material gas introduction unit connected to the reactive raw material gas supply unit may be provided on the plasma gun side. If these devices are operated before starting up the device, the time required to bring the vacuum vessel to a vacuum state, the time required to fill the required amount of reactive source gas in the device will be shortened, and the time required to start actual work will be reduced. It can be greatly shortened.

  In FIG. 2, the suction type plasma gun 5 includes a capillary tube 6, an RF electrode 9, and a plasma gun sheath portion 7 that accommodates them, and a distal end opening 8 of the capillary tube 6 is protruded inside the vacuum vessel 1. It is installed so that. The other end of the plasma gun 5, that is, the plasma gun rear end 11 on the side not protruding in the vacuum vessel is connected to the exhaust device 12. The position of the capillary tube tip opening 8 is fixed, but as described above, it is important to face the surface of the work 19 to be etched with a very slight gap. In the apparatus of the present invention, as will be described later, the sample table 15 on which the workpiece 19 is placed is moved by a micromanipulator, thereby adjusting the positional relationship between the two. The RF electrode 9 is disposed so as to surround a portion of the capillary tube 6 that is close to the tip opening 8, and is further connected to a power source 10 for RF microwave oscillation.

  FIG. 3 shows the sample stage 14 of the present invention. A sample stage 15 is attached to the sample stage 14, and the work 19 is placed on the sample stage 15. The sample stage 14 is provided with an X-axis micromanipulator 16, a Y-axis micromanipulator 17, and a Z-axis micromanipulator 18, so that the sample stage 15 is rough in the X-axis, Y-axis, and Z-axis directions. It is possible to move and finely move, and further, rotation around the Z axis (θ axis) and tilt at an arbitrary direction angle are possible in the state of coarse movement and fine movement. By appropriately driving these micromanipulators, the etching processing points on the surface of the work 19 can be positioned. The positioning is performed at a focal position under the head of the microscope 4 that is provided in a convex manner in the vacuum vessel 1. As described above with reference to FIG. 1, the sample stage 14 can automatically move between two fixed points, that is, the position of the head of the microscope 4 and the position of the capillary tip 8 of the suction type plasma gun. The sample stage 14 is placed on a precision guide (not shown) disposed on the base 13, and is driven by a drive mechanism (not shown) separate from the drive mechanism of the micromanipulator 16 in the X-axis direction. Movement between the two fixed points is performed.

  As described above, since the gap between the work 19 and the capillary tip opening 8 is narrowed, an undesirable phenomenon such as a crash due to contact between the work 19 and the apparatus accompanying the movement tends to occur. In order to avoid such a phenomenon, after the positioning of the work 19 under the head of the microscope 4 is completed, the position of the sample stage 14 is lowered (moved in the Z-axis direction), and in that state, the X-axis direction is moved. The sample stage 14 is moved between two fixed points and moved immediately below the suction-type plasma gun 5, and then the position of the sample stage 14 is raised to the original position and etching is performed. This vertical movement in the Z-axis direction is a large coarse movement in mm units. However, in order not to cause a deviation among the sample stage 14, the sample stage 15, and each micromanipulator, these parts are used as a base. It is effective to move the entire base 13 while it is placed on the base 13. That is, a Z-axis drive mechanism (not shown) that is completely different from the drive mechanism for the Z-axis micromanipulator 18 in the Z-axis direction is provided, and the base 13 is moved roughly up and down.

  FIG. 4 is a diagram showing an example of a local plasma etching method using a suction type local microplasma etching apparatus with a microscope using an SEM as a microscope of the present invention. The processing position on the workpiece is positioned under the SEM field of view, the sample stage is moved to a position below the plasma gun, and etching processing is performed. After processing, the sample stage is moved under the SEM field of view, and observation evaluation of the processed part is performed. If the evaluation is good (Good), the processing is completed. If the evaluation is bad (NG), the process is repeated as necessary, and the operation is stopped when the completion of the intended processing is confirmed. Reliable plasma etching is performed by this processing flow. When changing the machining position of a workpiece or when machining another workpiece, start from the initial positioning. When one of SEM and plasma is operating, the other is stopped.

The plasma etching processing method of the present invention will be specifically described with reference to FIGS. In the actual plasma etching process, first, the inside of the vacuum vessel 1 is evacuated using the exhaust device 12 and then, for example, CF ₄ (tetrafluoride) from the reactive raw material gas supply unit 2 through the gas introduction unit 3. Reactive source gas such as carbon) or O ₂ is supplied, and the vacuum container 1 is filled with the necessary amount. The work 19 placed on the sample stage 15 is placed under the head of the microscope 4, the micromanipulators 16, 17, 18 and a micromanipulator (not shown) are driven, and the work 19 is moved to the X, Y, and Z axes. Movement (coarse movement and fine movement), rotation about the Z axis (θ axis), inclination, and the like are performed as necessary to position the plasma etching processing point of the work 19. Thereafter, the base 13 is lowered by a certain distance in the Z-axis direction by the large coarse movement mechanism of the Z-axis, and the sample stage 14 is moved between two fixed points to a position below the capillary tip opening 8 of the suction type plasma gun 5. . After the base 13 is raised and returned to its original position, plasma etching processing is performed at the plasma etching processing point of the work 19. After the processing is completed, the base 13 is again lowered by a certain distance in the Z-axis direction, the sample stage 14 is moved between two fixed points to a position below the head of the microscope 4, and the plasma etching processing of the workpiece 19 is evaluated by microscopic observation. According to the observation evaluation result, the above-described operation is repeated if necessary. In this way, the plasma etching of the workpiece 19 is performed.

In the following, embodiments of the present invention will be described in accordance with examples, but the scope of the present invention is not limited thereby.
Example 1
Using the apparatus of the present invention shown in FIG. 1, an experiment for removing resist resin existing in a convex circuit shape on a device wafer by argon plasma was performed.
The experimental conditions are as follows.
Workpiece: SiO ₂ + organic film (film thickness 3μm)
Gas: Argon 30cc
RF output: 30W
Vacuum vessel pressure: 32.5Pa
Capillary tip diameter: φ2.5mm
The workpiece was irradiated with plasma at an angle of 10 degrees from the horizontal plane, and observed and photographed by SEM every 2.5 minutes. 6 to 9 show photographs of the surface of the workpiece after etching every 0, 5, 10, and 15 minutes. In the photograph, it is observed that the line width of the convex protrusions of the substantially T-shaped resist resin becomes narrower. The line width, which was 2.4 μm at the beginning, became 0.88 μm after 15 minutes of etching. The etching rate was about 0.1 μm / min.

  As described above, if the processing is advanced while alternately performing the etching processing and the SEM observation, the observation can be performed in a state close to real time. If the interval is shortened and recorded as a photograph, it is possible to leave a frame-invoice record.

Example 2
Using the apparatus of the present invention shown in FIG. 1, an etching removal experiment was conducted on the oxide film coated on the circuit wiring of the LSI device wafer by carbon tetrafluoride plasma.
The experimental conditions are as follows.
Work: LSI multilayer wiring board SiO ₂ insulating film gas: carbon tetrafluoride RF Output: 15W
Vacuum vessel pressure: 150Pa
Capillary tip diameter: φ0.4mm
Gap between capillary tip opening and workpiece: 0.1 mm or less FIG. 10 is a SEM photograph showing the state of the workpiece before the etching operation, and the entire surface is covered with a SiO ₂ insulating layer. FIG. 11 is an SEM photograph after local etching. The left half is removed by etching and the wiring is exposed, but the right half is not removed by etching and an unprocessed state remains. The boundary where the local etching is performed clearly appears. FIG. 12 is an enlarged SEM photograph of the etched portion, and it can be seen that all the wiring is exposed on the surface portion and the insulating layer remains in the third and lower layers.

  As described above, by using the suction type microplasma etching apparatus with a microscope according to the present invention, there is a problem that the conventional injection type microplasma etching apparatus has, that is, due to plasma diffusion and high-temperature gas diffusion. In addition to solving problems such as adhesion and contamination of foreign matter, contamination of the surface of the etching target other than the local area of the etching target due to reaction gas or evaporation gas, and the inside of the container, it becomes possible to process while observing the etching state with a microscope. It has a feature that accurate etching can be easily performed. Therefore, it is extremely important for the industry.

It is explanatory drawing of the suction type local microplasma etching apparatus with a microscope of this invention. It is explanatory drawing of the suction type plasma gun used for the suction type local microplasma etching apparatus with a microscope of this invention. It is explanatory drawing of the sample stage of the suction type local microplasma etching apparatus with a microscope of this invention. It is a diagram which shows the process of the plasma etching method using the attraction | suction type local microplasma etching apparatus with a microscope of this invention. It is a completion image figure which shows an example of the suction type local microplasma etching apparatus with a microscope of this invention. 2 is a SEM photograph of a workpiece used in Example 1 before processing. 2 is a SEM photograph of a workpiece after machining for 5 minutes in Example 1. 2 is a SEM photograph of a workpiece after 10 minutes processing in Example 1. 2 is a SEM photograph of a workpiece after 15 minutes of processing in Example 1; 6 is a SEM photograph of a workpiece used in Example 2 before processing. 4 is a SEM photograph showing the progress of etching of the workpiece of Example 2. It is a SEM photograph after the etching of the workpiece | work of Example 2. FIG.

Explanation of symbols

1: Vacuum container 2: Reactive source gas supply unit 3: Gas introduction part 4: Microscope 5: Suction type plasma gun 6: Capillary tube 7: Plasma gun sheath part 8: Capillary tip opening part 9: RF electrode 10: RF micro Power source for wave oscillation 11: Rear end of plasma gun 12: Exhaust device 13: Base 14: Sample stage 15: Sample stage 16: Micromanipulator for X axis 17: Micromanipulator for Y axis 18: Micromanipulator for Z axis 19: Workpiece

Claims (4)

  Suction-type local microplasma having a sample stage, a vacuum vessel provided with a gas introduction unit, a plasma tube having a capillary tube and an RF microwave oscillation electrode, a microscope, and a sample stage having a sample stage An etching apparatus, wherein the sample stage is in a vacuum vessel, the tip of the capillary tube is protruded in the vacuum vessel, the rear end is outside the vacuum vessel, and an exhaust device is connected, The microscope head is protruded in a vacuum vessel, and the reactive material gas for plasma introduced into the vacuum vessel from the gas inlet is sucked from the tip of a capillary tube. Type local microplasma etching equipment.   The sample stage is placed in an arbitrary direction and angle by moving a sample stage on which an object to be etched is placed, movement of the sample stage in the X-axis, Y-axis, and Z-axis directions, and rotation around the Z-axis. 2. The suction type local microplasma etching apparatus with a microscope according to claim 1, further comprising a driving device for tilting, and the sample stage is placed on a base at the bottom of the vacuum vessel.   The suction type local microplasma etching apparatus with a microscope according to claim 2, wherein the base on which the sample stage is placed is movable in the Z-axis direction.   The suction type local microplasma etching apparatus with a microscope according to any one of claims 1 to 3, wherein the vacuum vessel is depressurized by operating the exhaust device, and a necessary amount of the vacuum vessel in a vacuum state. The reactive source gas was introduced from the reactive source gas supply unit, the object to be etched placed on the sample stage was placed under the observation microscope barrel, and the processing point on the object to be etched was positioned. After that, the sample stage is moved so that the processing point of the etching target placed on the sample stage is located below the tip of the capillary tube of the plasma gun, and in this state, the voltage is applied to the RF microwave oscillation electrode. The plasma is generated at the processing point on the surface of the etching object by exciting the reactive source gas, and suction is performed by the exhaust device connected to the plasma gun. The surface of the etching object is etched by the generated plasma, and after the plasma etching process is completed, the sample stage is moved under the original observation microscope lens barrel, and the processing state of the etching object is determined by the observation microscope lens barrel. A microplasma etching method characterized by performing observation.

Images