JPH03241741A - Method and apparatus for local processing of energy beam - Google Patents

Abstract

PURPOSE:To prevent a misregistration due to a temperature change of the whole sample by locally applying a heating beam onto the sample and by locally heating only a processed part. CONSTITUTION:A cooling liquid is introduced from a substrate-cooling controller 26 into a cooling pipe 12 provided in a stage 11 to cool the whole sample 10 to a uniform temperature. Then, after a laser beam 24 from a laser oscillator 20 being a heating beam source is condensed by an objective lens 22, the beam is curved in the optical path by a reflecting mirror 23 and applied to the processed part of the sample 10. In this case, a laser output is changed by a laser controller 25, temperature conditions enabling obtaining a sufficient etching speed are found from the detection signal strength of a reaction product detector 19 and the laser output is fixed to the found conditions for the purpose of conducting a reactant etching. Thus, it is possible to prevent a misregistration caused by an expansion and contraction due to a temperature change of the whole sample.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to local processing or local film formation technology, and in particular, irradiates a sample with a focused energy beam in the presence of an etching gas or CVD gas, and The present invention relates to a method of locally etching or forming a film by inducing a chemical reaction, and an apparatus for carrying out the method.

[Conventional technology]

Ion beams and electron beams can be focused to 0.1 μm or less, and their energy can be used to perform microfabrication and local CVD. In recent years, research into practical use of photomask repair devices and LSI wiring repair devices using focused energy beams has been actively conducted.

By supplying etching gas to the sample surface at the same time as the focused energy beam irradiation, reactive etching is induced locally at the beam irradiation area, making it possible to perform high-speed, highly selective microfabrication. For example,
Journal Oba 4-Q Science and Technology, B 5 (1)
, 1987, pp. 423-426 (Journ
al of Vacuum 5science andT
technology, B 5 (1), 1987. p
423-426).

Furthermore, by supplying CVD gas to the sample surface at the same time as the focused energy beam irradiation, CVD can be performed locally at the beam irradiation section. An example is the device described in Japanese Patent No. 281349.

[Problem to be solved by the invention]

In order to manufacture or repair highly integrated and highly functional devices, fine processing and film formation are required with minimal damage. For this reason, local etching and local film formation using a combination of a focused energy beam and an etching gas or CVD gas are being actively researched. In such a local process, the energy provided by the focused energy beam induces a chemical reaction by the process gas, and temperature is an important parameter as a process condition.

Regarding temperature control, the experimental setup reported in Journal of Vacuum Science and Technology, Bi5(1), 1987, pp. 423 to 426, cited earlier as an example of local etching, Control is performed by a heater wrapped around the sample stage and a thermocouple provided on the sample stage.

In addition, as an example of local film formation, the above-mentioned Japanese Patent Application Laid-Open No. 62-2
In the device described in Publication No. 81349, the temperature control is as follows:
This is done using a cooling plate placed under the sample.

In all of the above conventional techniques, temperature control is performed by heating or cooling the entire sample. Therefore, when a large temperature difference is controlled, the entire sample expands and contracts, resulting in a problem that the processing position accuracy decreases. This problem,
This problem becomes even more serious when performing finer processing or film formation, or when processing or film formation is automatically performed based on positional data on element design. Furthermore, when etching a multilayer device sequentially from the top layer by local reaction, it is necessary to sequentially switch and supply the optimum etching gas for each layer. Because the combination of
It is necessary to sequentially switch and set the optimal process temperature. However, in the above-mentioned conventional technology, expansion and contraction of the sample is unavoidable in order to maintain the same temperature throughout the sample, which results in misalignment of the processing position for each layer, making it impossible to accurately process multilayer devices. there were.

The purpose of the present invention is to provide an energy beam local processing method that prevents positional shift due to temperature changes of the entire sample and that can always control the temperature of the processing area, film forming area, etc. to the optimum temperature, and an apparatus for implementing the same. Our goal is to provide the following.

[Means to solve the problem]

The above purpose is to cool down the entire sample using a cooling device installed in the sample stage, and to locally irradiate the sample with a beam generated from a heating beam source to locally target only the part to be processed. This can be achieved by heating.

Here, a laser beam, focused infrared light, or an electron beam may be used as the heating beam.

Further, in order to set the irradiation conditions of the heating beam, means for detecting the temperature distribution within the sample is provided.

[Effect]

While the entire sample is cooled down to a -like temperature by a cooling device provided in the sample stage, a heating beam is locally irradiated onto the sample to locally heat only the portion to be processed. For example, several μm
When processing around a corner or forming a film, the heating beam diameter should be set to 10
By focusing the irradiation on micrometers, the part to be processed or the part to be deposited can be heated to the desired temperature, and the area heated by the beam can be kept within a few tens of micrometers in diameter, even considering heat conduction. be able to. For example, if the sample is a Si wafer and is heated to 500° C. within a diameter of several tens of μm, the effect of elongation of the sample is 0.1 μm or less, and sufficient positional accuracy for processing and film formation can be obtained.

In addition, by using a means to detect the temperature distribution within the sample and monitoring the temperature distribution of the sample while it is being heated by the beam, the temperature distribution state can be fed back and the irradiation conditions of the heating beam can always be maintained at the optimum level. can.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In the following examples, an example in which an ion beam is used as an energy beam to perform local processing will be explained.
Local film formation can be performed in exactly the same manner.

Example 1: As a first example of the present invention, an example in which a laser beam is used as the heating beam will be described. Figure 1 shows the configuration of the device.

In the figure, an ion beam 3 extracted from an ion source 1 by an extraction electrode 2 is focused onto a sample 10 by a front-stage focusing lens 4 and a rear-stage focusing lens 8. At this time, the ion current is controlled by the opening diameter of the beam limiting aperture 5.

Then, the trajectory of the beam is bent by the blanking electrode 6, and the beam is interrupted by the blanking aperture, thereby controlling on/off of the beam. Further, the focused ion beam is deflected by the deflector electrode 9, and the beam is irradiated onto a desired area on the sample 10. During processing, for example, from the etching gas cylinder 15a to the valve 1.
6a.

Etching gas is supplied to the surface of the sample 10 through the gas nozzle 18a via the gas nozzle 16c. At this time, the flow rate of the etching gas is controlled by a flow rate controller 17a. Here, a plurality of etching gas supply systems (two systems in FIG. 1) are provided, and the optimum etching gas is successively supplied. For example, the etching gas cylinder 15a contains C.
Q-based gas (CQ2.CCΩ., 5icQ41 BeO2
etc.), and the etching gas cylinder 15b contains F-based gas (C
F4゜CHFa + "F6+ object detector 1
9, reaction products are detected, the material to be processed is monitored based on the type thereof, and the etching rate is monitored based on the amount generated. Here, the reaction product detector 19 may be one that performs mass spectrometry of reaction products (quadrupole mass spectrometer, sector magnetic field mass spectrometer, etc.) or one that performs spectroscopic analysis (fluorescence detector, photoelectron spectrometer, etc.). Note that 27 is a detector controller that controls the product detector 19.

In this example, in order to control the process temperature in local reactive etching, a cooling liquid is first introduced from the substrate cooling controller 26 into the cooling pipe 12 provided in the stage 11, and the entire sample 10 is cooled to a temperature similar to -. do. However, if the process temperature does not need to be below room temperature,
There is no need to provide a mechanism for cooling the sample 10. Next, a laser beam 2 from a laser oscillator 2o, which is a heating beam source, is emitted.
4 is focused by the objective lens 22, the optical path is bent by the reflecting mirror 23, and the processed portion of the sample 10 is irradiated with light 1-12-. At this time, the laser output is changed by the laser controller 25, temperature conditions are found from the detection signal strength of the reaction product detector 19 to obtain a sufficient etching rate, and the laser output is fixed at the found conditions to perform reactive etching. I do. At this time, by controlling the laser beam spot to about twice the area to be processed, the area to be processed is heated to a -like temperature, and the area affected by heat conduction is suppressed to within a few tens of μm square. suppresses the growth of
Sufficient machining position accuracy can be maintained. Note that as the laser, either a CW laser or a pulsed laser may be used.

Next, an example of the processing method in this embodiment will be explained with reference to FIG. 2. This is an example in which a two-layer wiring section was processed using an LSI as a sample. The layers to be processed include, in order from the top, a passivation film 29, an upper layer wiring 30, and an interlayer insulating film 3.
1. The lower layer wiring 32 is made of SiO2 and AΩ-Cu.
-8i are alternated. As an etching gas,
When processing 5in2, use XeF2 and AM-Cu-8i
5iCIA4 is used for pre-processing. Here, when etching 5in2 using XeF, a decrease in the adsorption probability of XeF2 becomes dominant as the temperature rises, and the etching rate rapidly decreases. The appropriate process temperature is 10
The temperature is below 0°C. On the other hand, Afl-Cu-8i is 5iCQ
4, the appropriate process temperature is 200°C to ensure that one of the reaction products, CuCQ3 (sublimation temperature 150°C or higher), is desorbed at a sufficient rate.
That's all. Therefore, in the example shown in FIG. 2, it is necessary to quickly control the temperature of the processed portion alternately to 100° C. or lower and 200° C. or higher during processing. On the other hand, in this example, the workpiece was heated to 100'C or less and 200'C or less in advance.
℃ or higher, detect changes in the processed layer using the reaction product detector 19, and switch between the two laser output conditions based on the detection results. Prompt temperature control can be achieved. Further, even in such rapid temperature control, since the temperature control is performed by localized beam spot heating, it is possible to suppress elongation of the sample and maintain sufficient processing position accuracy.

Embodiment 2: The configuration of an apparatus according to a second embodiment of the present invention is shown in FIG. This embodiment differs from the first embodiment in that a heating beam condition monitor 33 is provided on the stage 11 to measure in advance the output condition of the laser beam, which is the heating beam, and the other components are the same as the first embodiment. This is similar to the first embodiment.

As in the processing example described in the first embodiment, if the appropriate process temperature is known and the laser output conditions for heating the workpiece to that temperature can be measured, it is easy to simply control the laser output during processing. The temperature of the processed part can be controlled to the appropriate process temperature. Therefore, a heating beam condition monitor 33 is provided on the stage 11 to measure the relationship between the laser output and the temperature of the workpiece.

An example of this heating beam condition monitor 33 is shown in FIG.

The main body of the heating beam condition monitor 33 is made of a material having approximately the same thermal conductivity as the element to be processed, and the element structure is the same as that of the element to be processed. For example, the example in Fig. 4 shows an example of heating beam condition monitoring when an LSI with three-layer wiring is targeted as the device to be processed. 35 thermocouples in each layer and lower layer
a.

35b and 35c are formed. In addition, when laser light is irradiated onto the workpiece, the heating condition changes depending on the opening of the machined hole and the depth to the workpiece surface. Create a simulated hole. When measuring, first, the laser beam 24a is irradiated to the upper layer machined hole, the output is changed, and the upper layer thermocouple 3
From the measurement result of the output H1-H2 of 5a, the relationship between the laser output and the upper layer heating temperature is determined. Similarly, the relationship between laser output and heating temperature for the intermediate layer and lower layer is determined. Thermocouple 35d installed around the heating temperature measurement of each layer
From the output S□-82, the influence of heat conduction to the surroundings is also measured. These measurement results are stored in the memory within the overall control CPU 28.

In actual processing, it is possible to quickly set the optimum laser output conditions that can bring the temperature of the layer to be processed close to the appropriate process temperature and suppress the influence of heat conduction to the surroundings.

Embodiment 3, Embodiment 4, and Embodiment 5: The configurations of the main parts of apparatuses according to third, fourth, and fifth embodiments of the present invention are shown in FIGS. 5, 6, and 7, respectively.

These embodiments differ from the second embodiment in that the introduction path of the laser beam is changed, and the other configurations are the same as in the second embodiment. Here, only the introduction paths of each laser beam will be explained.

In the third embodiment shown in FIG. 5, a laser beam 24 from a laser oscillator 20 is expanded by an optical path extender 36, the optical path is bent by a reflecting mirror 23, and then focused onto a sample 10 by reflecting objective lenses 37a and 37b. Irradiate light.

In the fourth embodiment shown in FIG. 6, the laser beam 24 from the laser oscillator 20 can be
is irradiated from an oblique direction, and the sample 10 is
A focused beam of light is irradiated directly onto the top.

In the fifth embodiment shown in FIG.
After passing through the interior, the light is focused by an objective lens 22 provided at its tip and irradiated onto the sample 10.

Embodiment 6: The configuration of an apparatus according to a sixth embodiment of the present invention is shown in FIG. This embodiment differs from the first embodiment in that it includes an infrared temperature camera 40 and a temperature image processing device 41 for monitoring the temperature distribution on the surface of the sample 10. The other configurations are the same as in the first embodiment.

In the figure, infrared radiation emitted from the surface of a sample 10 is detected as an image by an infrared temperature camera 40, and the temperature distribution on the surface of the sample 10 is quantitatively monitored. The temperature image processing device 41 calculates temperature data at each point based on the monitor results,
In the overall control CPU 28 to which this data is sent,
Analyze whether the processed part is at a predetermined temperature and whether the influence of heat conduction to the surrounding area is suppressed. and,
Based on this analysis result, feedback is applied to the substrate cooling controller 26 and the laser controller 25,
Always maintain optimal heating conditions.

Next, the heating beam condition setting method in this example will be explained in the ninth section.
This will be explained using figures. First, the board cooling controller 26
After cooling the sample 10 to a predetermined temperature, the sample 10 is irradiated with a heating laser beam 24, and while the beam output is varied by a laser controller 25, local reactive etching is performed. At this time, the temperature image processing device 41 monitors the temperature distribution on the surface of the sample 10, and the detector controller 27 monitors the amount of reaction products generated.

The amount of reaction products generated is indicated by D, as shown in the graph on the right side of Figure 9, where the amount of reaction products, that is, the etching rate increases as the beam output increases, that is, the temperature of the processed part increases. (for example, if AQ is 5iC)
There are two cases: a case of etching using Qa) and a case of decreasing E (for example, a case of etching S i O2 using X e F 2). In any case, the obtained relationship determines an appropriate beam output range for obtaining a sufficient etching rate. On the other hand, from the results of the temperature distribution monitor, for example, the line L including the processed part M in FIG.
If we pay attention to the temperature distribution graph on −L, as the beam output increases, the temperature distribution changes as follows: A −+ 13−+ When is greater than or equal to TH, the temperature condition of the processed part is set to be greater than or equal to TH, and in order to prevent elongation due to surrounding heating due to heat conduction, the temperature is set to be less than or equal to TL at a radius of R or more centered on the processed part.This condition The temperature distribution that satisfies the following is, for example, only B among A, B, and C.

As described above, the beam output range for obtaining a sufficient etching rate is determined from the results of monitoring the amount of reaction products, and the output range for suppressing the influence of sample elongation is determined from the results of monitoring the temperature distribution. Then, the optimum beam output range is determined from the conditions that satisfy both of them, and the laser controller 25 sets the laser output to the optimum output range to perform processing.

Although it is possible to set the heating beam conditions as described above, on the other hand, there are cases where the temperature required to obtain a sufficient etching rate is extremely high, or when the processing size becomes small and the effects of heat conduction may occur. If the conditions for suppressing this become more severe, it may not be possible to fully satisfy both conditions. In such a case, the 10th method prioritizes the conditions for obtaining a sufficient etching speed and corrects the distortion caused by thermal conduction in the sample with respect to the processing position data.
This will be explained using figures. Similar to the method shown in FIG. 9, local reactive etching is performed while the laser output is varied by the laser controller 25, and the amount of reaction products is monitored by the detector controller 27, and the temperature distribution is monitored by the temperature image processing device 41.

First, from the results of monitoring the amount of reaction products, a beam output range that provides a sufficient etching rate is determined.

Then, based on the results of monitoring the temperature distribution, conditions are added to suppress temperature distortion of the sample as much as possible, and the optimum beam output is set. Next, at the set optimum beam output, the remaining sample distortion due to thermal conduction is calculated from the temperature distribution and the thermal expansion coefficient of the sample. Based on the calculated amount of distortion, the overall control CPU 28 corrects the machining position data and applies feedback to the stage 11 to maintain high machining position accuracy.

Example 7: FIG. 11 shows the configuration of a device according to a seventh embodiment of the present invention.

This embodiment is based on the sixth embodiment.

The heating beam is replaced with a focused infrared light beam instead of a laser beam, and the means for measuring the effect of heat conduction around the workpiece is replaced with a plurality of thermocouples instead of an infrared temperature camera. The other configurations are similar to the sixth embodiment.

In the figure, infrared light from an infrared light source 42 is transmitted to a rotating elliptical mirror 4.
3 and irradiates it onto the sample 10. The output of infrared light is controlled by an infrared light source controller 45. Also,
The temperature distribution within the sample 10 is determined by a plurality of thermocouples (numerals 44a, 44b, 4 in FIG. 11) provided within the stage 11.
(3 pieces of 4c are shown).

Here, an example of a thermocouple element for monitoring the planar temperature distribution within the sample 10 is shown in FIG.

In this configuration, thermocouple elements 47 are constructed by arranging measurement points of thermocouples 44 in a grid pattern within a plane, and wiring lines for extracting data from each point to the outside. This can be manufactured as a thin film thermocouple element, for example, by a thin film patterning process used in semiconductor manufacturing. By monitoring the temperature distribution within the sample 10 using this element, the influence of the heat transfer source can be evaluated and the output of the heating beam can be optimally controlled in exactly the same manner as in the sixth embodiment.

Embodiment 8 and 9: The configurations of devices of eighth and ninth embodiments of the present invention are shown in FIGS. 13 and 14, respectively. These examples are:
This embodiment is similar to the second embodiment except that the heating beam used in the second embodiment is replaced by an electron beam instead of a laser beam.

In the eighth embodiment shown in FIG. 13, an electron beam extracted from an electron source 48 is focused by a focusing lens 50 and irradiated onto a sample 10 for spot heating. At this time, the electron beam energy, beam current, and focused beam diameter are all controlled by the electron beam controller 52. In addition,
This heating electron beam can also have the function of neutralizing the charge of the ion beam 3 and preventing charge-up of the sample 1o.

In the ninth embodiment shown in FIG. 14, the electron beam extracted from the electron source 48 is focused by a focusing lens 50, then its trajectory is bent by a deflector alignment unit 53, and the sample 10 is irradiated from on the axis of the ion beam 3. do. In this embodiment, since the heating electron beam is irradiated onto the sample 10 from directly above, the part to be processed can be efficiently heated without being affected by minute irregularities on the surface of the sample 10.

〔Effect of the invention〕

According to the present invention, when performing local processing or local film formation using an energy beam and a process gas, it is possible to locally control the temperature by irradiating the heating beam, so that the temperature of the entire sample changes. This has the effect of preventing positional deviations caused by expansion and contraction due to heat transfer, and controlling the temperature of the part to be processed or the part to be film-formed to an optimum temperature of 23 to 24 degrees Celsius.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an apparatus according to a first embodiment of the present invention, FIG. 2 is an explanatory diagram showing an example of a processing method in the first embodiment,
FIG. 3 is a configuration diagram of the apparatus of the second embodiment, FIG. 4 is an explanatory diagram showing an example of a heating beam condition monitor in the apparatus of the second embodiment, and FIGS. 5, 6, and 7. 8 is a block diagram showing the main parts of the apparatus of the third, fourth and fifth embodiments, respectively. FIG. 8 is a block diagram of the apparatus of the sixth embodiment. FIG. 9 is a heating beam diagram of the sixth embodiment. Explanatory diagram of condition setting method, 10th
The figure is an explanatory diagram of the machining position data correction method in the sixth embodiment, FIG. 11 is a configuration diagram of the apparatus of the seventh embodiment, and FIG.
The figure is an explanatory diagram showing an example of a thermocouple element in the device of the seventh embodiment, and FIGS. 13 and 14 are configuration diagrams of the devices of the eighth and ninth embodiments, respectively. Explanation of symbols 1...Ion source 3...Ion beam 10
...Sample 11...Stage 12...
Cooling pipes 15a, b...Etching gas cylinders 17a, b...
・Flow rate controllers 18a, b...Gas nozzle 19...Reaction product detector 20...Laser oscillator 22...Objective lens 23
...Reflector 24...Laser beam 25...
Laser controller 26... Substrate cooling controller 27... Detector controller 28... Overall control CPU 33... Heating beam condition monitor 35a''d... Thermocouple 36... Optical path expander 37
... Reflection objective lens 39 ... Optical fiber 40 ... Infrared temperature camera 41 ... Temperature image processing device 42 ... Infrared light source 43 ... Rotating elliptical mirror 44
．． 44a-c...Thermocouple 45...Infrared light source controller 47...Thermocouple element 48...Electron source 50...
・Focusing lens 52...Electron beam controller 53...Deflector axis alignment unit

Claims (1)

[Claims] 1. In an energy beam local processing method in which a sample is irradiated with an energy beam in a processing gas atmosphere and energy beam processing is performed locally at the irradiated part of the energy beam, a heating method different from that of the energy beam is used. An energy beam local processing method characterized by irradiating a beam onto a target part of a sample to locally heat the target region. 2. The energy beam local processing method according to claim 1, wherein the processing gas is an etching gas, and the energy beam local processing is an energy beam local processing that locally performs reactive etching. Processing method. 3. The energy beam local processing method according to claim 1, wherein the processing gas is a CVD gas, and the energy beam local processing is an energy beam local film formation in which CVD is performed locally. Method. 4. In the energy beam local processing method according to any one of claims 1 to 3, when the region to be processed is locally heated with the heating beam, the temperature distribution and processing speed of the sample are detected; An energy beam local processing method comprising controlling the output of the heating beam based on the detection result so as to sufficiently suppress thermal distortion calculated from the temperature distribution of the sample and obtain a sufficient processing speed. 5. Consists of an energy beam source, a focusing optical system, a stage, a processing gas supply means, a reaction product detector, and a power supply controller that drives them, and irradiates the sample with an energy beam in a processing gas atmosphere to locally generate energy. An energy beam local processing device for performing beam processing, characterized in that the energy beam local processing device is provided with heating beam irradiation means for locally heating a region to be processed. 6. The energy beam local processing apparatus according to claim 5, wherein the processing gas is an etching gas, and the energy beam local processing is an energy beam local processing that locally performs reactive etching. Processing equipment. 7. The energy beam local processing apparatus according to claim 5, wherein the processing gas is a CVD gas, and the energy beam local processing is an energy beam local film formation in which CVD is performed locally. Device. 8. The energy beam local processing device according to any one of claims 5 to 7, wherein the heating beam irradiation means is a condensed laser beam irradiation means. 9. The energy beam local processing apparatus according to any one of claims 5 to 7, wherein the heating beam irradiation means is a condensed infrared light irradiation means. 10. The energy beam local processing apparatus according to any one of claims 5 to 7, wherein the heating beam irradiation means is a focused electron beam irradiation means. 11. An energy beam local processing device according to any one of claims 5 to 10, further comprising means for detecting the temperature distribution of the sample. 12. The energy beam local processing device according to claim 11, wherein the means for detecting the temperature distribution of the sample is an infrared temperature camera. 13. The energy beam local processing device according to claim 11, wherein the means for detecting the temperature distribution of the sample is a plurality of thermocouples provided on a stage on which the sample is mounted. .