JPH03166389A - Method and device for energy-beam working - Google Patents

Abstract

PURPOSE:To apply energy-beam working with high efficiency at a high rate by controlling the ratio of the amt. of a gaseous etchant to be supplied to the irradiating quantity of an energy beam to optimize the reaction balance. CONSTITUTION:A material to be worked is irradiated with an energy beam such as an electron beam in a gaseous etchant atmosphere, and the irradiated part is locally subjected to reactive etching. In this energy-beam working method, the ratio of the amt. of etchant to be supplied to the irradiating quantity of energy beam is controlled to obtain an optimum balance where the molecules of the etchant react with the atoms of the material most efficiently. The material is matched with the etchant, a test working is carried out while conforming the energy of the beam and the temp. of the material to those in actual working, and the optimum balance is obtained from the ratio of the amt. of etchant to be supplied imparting the maximum working yield to the irradiating quantity of energy beam. Consequently, the energy-beam working is applied with high efficiency at a high rate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to energy beam processing technology, and in particular, a processing method in which an energy beam is irradiated in the presence of an etching gas to induce reactive etching in the irradiated area; and related to the same processing equipment.

[Conventional technology]

Electron beams and ion 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, photomask repair equipment and LS using focused ion beam processing and local CVD have been developed.
The practical application of I-wiring correction devices is being actively promoted. An example of this type of focused ion beam processing apparatus is Japanese Patent Application Laid-Open No. 61245553. Processing using a focused ion beam in this known technique is sputter processing in which sample atoms are knocked out by the irradiated ion beam.

In addition to the above-mentioned known techniques, thermal processing using electron beam energy is also known.

Furthermore, there is a processing method in which ion beam or electron beam is irradiated in the presence of etching gas to induce reactive etching in the beam irradiated area, and this type of technique is known, for example, in JP-A-63-228720. .

[Problem to be solved by the invention]

In order to increase the integration and functionality of LSIs and optical devices, wiring and elements are becoming more multi-layered, patterns are becoming finer, and each layer is becoming thinner. Processing methods for manufacturing or modifying devices with such high density require processing that is minute and does not damage the lower layer of the processed layer.

Furthermore, as device structures become more complex, the processing steps required to modify these electronic components tend to become increasingly complex, leading to an increase in the number of processing steps.

For this reason, there is a demand for the development of processing techniques that are faster and have higher yields.

Conventional electron beam processing apparatuses using a sputter processing method or a thermal processing method have the following problems when processing high-density devices.

(a) To obtain a fine beam, there is a limit to the beam current, making high-speed processing difficult. (BL has low selectivity with respect to the material of the workpiece, and it is difficult to process each thin layer without damaging the underlying layer.

In contrast, in the method of irradiating an ion beam or electron beam in the presence of an etching gas (beam-assisted reactive etching), processing proceeds mainly through a chemical reaction between the etching gas and sample atoms. By controlling parameters such as pressure and beam energy to increase the reaction probability, it is possible to perform high-speed processing ten times faster than spatter processing or thermal processing. Further, by selecting the type of etching gas, the selectivity for the lower layer of the processed layer can be increased, and accurate processing can be performed without damaging the lower layer.

In this beam-assisted reactive etching, the amount of etching gas supplied to the sample surface is an important parameter that determines the processing speed. For example, JP-A-63-2287
In the apparatus described in No. 20, it has been shown that even if the ion beam irradiation amount is constant, the processing speed changes when the gas pressure near the target surface is changed. Also, the third
Proceedings of the 6th Applied Physics Association Lecture 4a-V-7,
In P1060, it has been shown that when not only the etching gas supply amount but also the ion beam irradiation amount is changed, the processing speed increases depending on the ratio of the gas irradiation amount and the ion irradiation amount.

The above-mentioned gas irradiation amount is a concept expressed by grasping the supply status of etching gas in the energy beam irradiation part in a ξchronological manner, and means the number of gas molecules supplied within unit time and unit area. .

When processing high-density multilayer devices using beam-assisted reactive etching in actual industrial production, it is necessary to switch the etching gas depending on each layer. In this case, the combination of etching gas and material of the workpiece changes sequentially.

However, the above-mentioned known techniques do not take into consideration the case where parameters such as the combination of etching gas and workpiece material, ion beam energy, sample temperature, etc. change, and the ratio of gas irradiation amount to ion irradiation amount is not considered. It has been impossible to maintain optimal conditions in response to changes in conditions and always perform highly efficient, high-speed machining. Therefore, in extreme cases, there is a problem in that machining is performed at a low efficiency of 1/100 or less of the machining speed under optimal conditions. These problems also exist in conventional beam-assisted reactive etching using an electron beam.

The purpose of the present invention is to optimize the ratio of gas irradiation amount to beam irradiation amount in response to changes in the combination of etching gas and workpiece material, energy beam energy, and sample temperature in response to changes in these conditions. An object of the present invention is to provide an energy beam machining method and an apparatus therefor, which can be controlled so as to always perform highly efficient and high-speed machining.

[Means to solve the problem]

In order to achieve the above objective, the inventors of the present invention have repeatedly conducted experimental research on the relationship between the ratio of gas irradiation amount to ion irradiation amount and processing speed, and as a result, discovered the following law and conducted experiments. I confirmed this.

(i) When the ratio of gas irradiation amount to ion irradiation amount is increased,
The processing speed per ion gradually increases, reaches a peak, and then declines. At this time, the change in machining speed is 100 times or more. In addition, when the ratio of both irradiation doses is within one digit before and after the condition where the machining speed peaks, the change in machining speed is also l
Within an order of magnitude.

(ii) If the combination of etching gas and workpiece material, ion beam energy, and sample temperature are changed, the above (i)
The relationship between terms changes. In other words, the conditions under which the machining speed reaches its peak also change.

In order to utilize the above-mentioned rules in practice to achieve the above-mentioned objective (high-speed processing with high efficiency), the present invention sets the combination of etching gas and workpiece material, the energy of the energy beam, and the temperature of the sample. After that, before starting processing, the optimal balance between the gas irradiation amount and the beam irradiation amount under the conditions is determined, and processing is performed while maintaining this optimal balance.

There are the following two methods for finding the optimal balance between the gas irradiation amount and the beam irradiation amount.

(a) Set the combination of etching gas and workpiece material, energy beam energy, and sample temperature to the same conditions as in actual processing, and perform trial processing while changing the ratio of gas irradiation amount to beam irradiation amount, Find the optimal balance that gives the peak machining speed.

(bl) Set the combination of etching gas and workpiece material, energy beam energy, and sample temperature to the same conditions as in actual processing, and calculate the energy distribution given to the sample surface by one incident energy particle through simulation. The maximum number of sample atoms in which a reaction occurs is determined from the surface energy distribution.The optimum balance is when the etching gas molecules are supplied so that all of these atoms react.

In order to obtain the optimal balance between the gas irradiation amount and the beam irradiation amount as described above, in an energy beam assisted reactive etching device equipped with a means for irradiating an energy beam and an etching gas onto a sample, deflection control of the energy beam is performed. A control unit, a power supply control unit, a gas irradiation amount control unit, and a sample temperature control unit are provided, and an overall control CPU is provided which controls each of the control units based on the optimum reactive etching conditions stored in a data memory.

[Effect]

When performing trial machining of the fat term, create a trial machining program in advance and use the entire system. An input is made to the IIICPU, and instructions are sent from the overall system @cpu to the beam deflection control section and the gas irradiation amount control section according to this program, and processing is performed while automatically changing the ratio between the gas irradiation amount and the beam irradiation amount. This makes it possible to find the conditions for the fastest processing speed, that is, the optimum balance between the gas irradiation amount and the beam irradiation amount.

In the above method (using the bl term simulation), a program (Monte Carlo simulation, etc.) that calculates the energy given to the sample surface by one incident particle is input into the overall control CPU in advance.
The energy distribution on the surface of the sample per incident particle is determined by elation, and the number of sample atoms at which a reaction occurs with a sufficient probability is calculated. The optimum balance between the gas irradiation amount and the beam irradiation amount can be determined from the conditions for supplying etching gas molecules such that all the atoms react.

Once the optimal balance is determined, the overall control CP is determined based on this.
The gas irradiation amount control section and the beam deflection control section are controlled by instructions from U.

When the combination of etching gas and workpiece material changes, the optimal balance between gas irradiation amount and beam irradiation amount also changes, so when processing multilayer devices, for all combinations of etching gas and workpiece material in the target processing, It is best to find the optimal balance.

Additionally, if the beam energy, that is, the accelerating voltage, or the sample temperature changes, the optimal balance between the gas irradiation amount and the beam irradiation amount will change, so during processing, the beam power control unit and sample temperature control unit control the acceleration voltage, respectively. and maintain the sample temperature under constant conditions.

〔Example〕

Hereinafter, an example of implementing the method of the present invention using the apparatus of the present invention will be described with reference to the drawings. Although this embodiment will be described with reference to the case where an ion beam is used as the energy beam, it can be carried out in exactly the same way when an electron beam is used.

In ion beam assisted reactive etching, there are two types of ion beam irradiation methods: focused ion beam irradiation and shower ion beam irradiation, and two types of etching gas supply methods: a method using a nozzle and a method using a subchamber. There is.

Figure 2 shows the beam parameters for focused ion beam irradiation. Processing is performed by focusing the ion beam 1 and scanning the processing area 2 as shown by the arrows in the figure. Each beam parameter is represented by the following symbols.

Beam current: IB Beam diameter: d Scan time: t. Number of scanning lines: N, Area of spot area within radius slI (cnl)
is represented by 4. The number of ions irradiated per unit time and unit area within this spot area during focused ion beam irradiation is called the ion flank δ. ,,(ton/cot・sec
) then δ. . 7 is given by the following equation.

Here, e is the elementary charge: 1.6X10-'' (C).

Figure 3 shows the beam parameters for shower ion beam irradiation. This figure shows the case where a shower-like ion beam is uniformly irradiated over a wide area and the irradiation area is processed at once.The beam parameters are beam current density=D, (A/an ). At this time, is the shower ion beam irradiated part irradiated per unit time and per unit area? The number of ions is expressed as the ion flux δion(t
on/cnl-sec) then δ■. 7 is given by the following equation.

δ,. =D・ ... (3) e FIG. 4 shows gas parameters when a nozzle is used.

The chamber 4 is kept in a vacuum, and the gas nozzle 5 is placed on the surface of the sample 3.
At the same time, etching gas is supplied from the ion beam 1, and at the same time, the ion beam 1 is irradiated to perform processing.

If the amount of gas molecules supplied per unit time and unit area on the surface of sample 3 is δ9■ (molecules/crA-sec), then this δ
Regarding 9■, the following three parameters are important.

Gas flow rate: Q (Pa-rd/sec
) Nozzle opening area: S,, (cn!) Nozzle distance between samples: L. (cd) Here, to control the gas flow rate Q, it may be controlled by the etching gas pressure P filled in the buffer chamber 6 connected to the nozzle, or it may be controlled by the etching gas pressure P filled in the buffer chamber 6 connected to the nozzle, or by the etching gas pressure P filled in the buffer chamber 6 connected to the nozzle. The etching gas flow rate may be directly controlled.

When the number of gas molecules blown out per unit time from the nozzle tip opening is N f1g (molecules/sec), Q RT (4) is obtained, and δqss is given by the following equation.

Here, N0 is the number of avocados: 6.02 x 1023
(mol-'), R is gas constant: 8.31 (J
-mol-'·K-'), T(K) is the etching gas temperature.

Further, k, is a coefficient representing the spread of gas from the nozzle until it reaches the sample surface, and is a function of the nozzle-sample distance L9.

k,=f (L,)...
(6) The relationship between k7 and L depends on the shape of the nozzle opening,
Although it is influenced by the arrangement of parts between nozzle samples and is unique to each device, k and l are roughly proportional to the square of L.

FIG. 6 is a schematic diagram depicting a case where a subchamber is used in FIG. 5; The chamber 4 is kept in a vacuum, the subchamber 7 containing the sample 3 is filled with etching gas, and the surface of the sample 3 is irradiated with the ion beam 1 to perform processing. Subchamber 7
The etching gas density ngms (molecules/cffl) in is expressed by the following equation using gas pressure P (Pa) and gas temperature T (K).

Pnf8! =No ・10-b”・(7
) RT The mean square velocity of the etching gas is C ( ctn /
sec), the number of gas molecules supplied to the surface of the sample 3 per unit time and unit area is 69. , (molecule/crA −
sec) is given by the following equation.

Figures 6 and 7 show the ratio of gas flux to ion flux when performing ion beam assisted reactive etching by combining the above two types of ion beam irradiation methods and two types of etching gas supply methods. I will explain.

FIG. 6 shows temporal changes in gas flux and ion flux when focused ion beam irradiation is used. Regardless of whether a nozzle or a subchamber is used as the gas supply method, the gas flux at any point within the processing area is a constant value δgas as shown in Figure 6(a), and does not change over time during processing. do not have. On the other hand, the ion flank at any point within the processing area is reflected in the plane scanning of the focused ion beam as shown in Figure 6 (b).
) changes periodically as shown. t+ (sec) in the figure
represents the time it takes the focused ion beam to pass through a certain point during one scan, and is expressed as follows. In addition, when the interval between the scanning lines is narrower than the beam diameter d, the beams from scanning several times before and after the arbitrary point pass overlappingly, but N+ (times) in the figure indicates the number of times the beams pass through this overlappedly, becomes. Any point at time t,,N. This occurs in every surface scan, i.e. with period T − ”
This will occur at intervals of t*·N, (sec).

Here, since the shape of the focused ion beam is close to a circle, t, is not constant, and the ion distribution within the beam diameter is not uniform (close to Gaussian distribution), so the ion flux δ, for each 1. 7 is not constant either. However, in this embodiment, t1 is constant and the ion flux δ. . The flux balance is calculated assuming that 7 is also constant.

If the processing area is sufficiently small compared to the beam diameter, the flux balance of gas and ions can be determined and controlled with sufficient accuracy for practical use based on the above assumption.

On the other hand, when processing an area with the same size as the beam diameter, the ion distribution within the beam diameter cannot be ignored, so it is necessary to calculate the ion flux by integration, for example, assuming the above ion distribution as a Gaussian distribution. . From Figure 6, when using focused ion beam irradiation, the Franks balance B (molecules/ion) is the ratio of the gas and ion fluxes irradiated per unit area within the surface scanning time T. is defined, B is given by the following equation.

Here, k is a coefficient representing the gas adsorption probability, and is a function of the sample temperature T, (K).

kr =g (T0) (auto) Also, the αυ equation is transformed by the equation (9) and the αω equation to obtain the following equation.

Furthermore, the following equation is obtained using equation (11) and equation (2).

L. L, B=k, 04) Ii+ However, ? FIG. 7 shows temporal changes in gas flux and ion flux when shower ion beam irradiation is used. Regardless of whether a nozzle or a subchamber is used as the gas supply method, the gas flux at any point within the machining area is a constant value δ,■, as shown in Figure 7(a), and does not change over time during machining. do not have. In addition, when a shower ion beam is used, the ion flanks at any point within the processing area are also
As shown in , there is no time change during processing with a constant value δion. Therefore, the ratio of the supply amount of gas molecules and irradiated ions is simply the gas flux δwag and the ion flux δ■. 9
Since it can be defined as the ratio of flux balance B (molecule/
ion) is given by the following equation.

? , ■ B=k,
...a sai δ5. 7 (Specific Example 1) Here, as in equation 01), k is a coefficient representing the gas adsorption probability. By always controlling B in the α9 equation to the optimum value, when using a shower ion beam,
This enables the most efficient etching.

(Example 1) In this example, a processing method using focused ion beam irradiation and gas supply through a nozzle to find an optimal flux balance through trial processing will be described.

The trial processing method will be explained using FIGS. 8 and 9. When using focused ion beam irradiation and gas supply through a nozzle, the flux balance is expressed by the equation (141) shown above,
It is proportional to δ9.1 and LX −L, that is, it is proportional to the gas flow rate Q and the processing area. Therefore, as shown in FIG. 8, the machining area is S. IOS. Machining is performed while automatically changing the machining area so that the flow rate is 10”S, and the flow rate Q is
Trial machining is performed by controlling it so that it becomes 103Q. As a result, the product of flow rate Q and machining area is from Q-S to 10'Q-S
It can be varied over a wide range. That is, processing can be performed while changing the flux balance B over a wide range.

The processing yield (number of processed atoms per incident ion) for each processed hole is calculated, and the change with respect to flux balance B is plotted. FIG. 9 shows an example of the result of trial machining obtained in this manner. The fronts are interpolated by the least squares method, etc., and the value of the flux balance that gives the peak of the machining yield is determined, and this becomes the optimum flank balance Bad.

A flowchart of the processing method using trial processing is shown in FIG. The combination of the target material to be processed and the etching gas, and the substrate temperature T0' during processing are set. Furthermore, a target machining yield Y required for the process is set. Beam parameters and gas parameters for trial processing are set, and the optimum flux balance Bad is calculated using the above trial processing method. Here, if the peak value is not found in the graph of FIG. 9, Bad cannot be found, so B. In other words, processing is continued until ? Repeat trial processing until a peak appears in the B
Store ■ in the data memory.

In actual processing, first the substrate temperature T0 and acceleration voltage ■.

Set it to be the same as during trial machining. As a result, the optimum flux balance in actual machining becomes equal to that in trial machining. Next, beam parameters are set and ion flux δion is calculated. Gas parameters are set so as to achieve the optimum flux balance for this δton. Specifically, gas parameters are set, gas flux δgas is calculated, and flux balance B is calculated. First, B is B obtained through trial processing. Determine whether it is within one digit before or after , and if it is, start processing as is. If not, B set the target machining yield {+! Y. Determine whether it is larger, and if it is larger, start machining. B is Ba
If it deviates from within one digit before and after d and is smaller than Yp, the gas flow rate Q is increased or decreased and reset, and the flux balance determination is repeated again. As described above, the optimum Franks balance B was obtained through trial machining. Machining can be performed under conditions of flask balance that are sufficiently close to that, and by maintaining each machining parameter at the set conditions during machining, efficient high-speed machining can be performed.

(Example 2) In this example, a processing method using focused ion beam irradiation and gas supply through a nozzle to find an optimal flux balance through simulation will be described.

A simulation for determining the optimum flux balance will be explained using FIG. 1l. As a prerequisite for the simulation, the material to be processed, incident ion species, ion energy, and substrate temperature are determined in advance. As shown in FIG. 11(a), when one incident ion 8 is incident on the sample 3, a chain of collisions occurring within the sample is determined by Monte Carlo simulation. As a result, when one ion is incident,
The energy distribution applied to the sample surface is determined. Figure 11f
As shown in b), if we take the polar coordinates with the ion incidence point as the origin, we get an input with a peak at the origin determined by simulation?
There is an energy distribution due to ions and a uniform energy distribution due to substrate temperature. The actual energy distribution is determined by the sum of the two, and from the determined energy distribution, the distribution of the reaction probability ρ between sample atoms and etching gas molecules is shown in Figure 11 (
It can be found as shown in C). This gives a sufficient reaction probability ρ. It is calculated that the region exceeding S. (c+a) is determined by the following formula.

S. =πR2... (14
9 Furthermore, the surface atom density of the sample is 6■1 (atoms/c1lI
), the maximum number of atoms processed per ion, that is, the maximum processing yield Y. (atom/ion) is Y. =δ1.・S
．． ... Become αno. The state where enough gas molecules are supplied to cause all the atoms of Y0 to react is the state of optimal flux balance, and therefore Y1 becomes equal to the value of optimal flux balance.

The first flowchart of the method using simulation
Shown in Figure 0. A combination of a target material to be processed and an etching gas, and a substrate temperature T0 during processing are set. The type of reaction is determined by the combination of the material to be processed and the etching gas, and the activation energy E0 and reaction time t0 of the reaction are determined. Next, the target machining yield Y required for the process is set. The beam parameters are set, and the maximum processing area S0 per ion is calculated by the above simulation. Ion flux δ. 0, , and calculate δfan·S1t0. δton・S.・t0
The value of is the area S. during the reaction time t0. Since it represents the number of ions incident on δ. . 7. If S1to is larger than 1, before the reaction by one ion finishes,
The next ion will be incident, and the ions will be wasted. Generally t. Although there are few cases where this happens because the value is as small as about 10-' sec, in order to prevent ions from being wasted, δto,,・S.・t0
Set the beam parameters so that ≦1, and move on to the next step. In the next step, the S. The maximum machining yield Y8 is calculated from δ, which was set in the previous step. 0, the gas parameters are set so that the flux balance is sufficiently close to Y1.

The specific method of setting gas parameters is the same as in the first embodiment. After all, machining can be started under flux balance conditions sufficiently close to the maximum machining yield Y0 obtained through simulation, and by maintaining each machining parameter at the set conditions during machining, efficient high-speed machining can be performed.

(Example 3) In this example, a processing method uses focused ion beam irradiation and gas supply through a nozzle, and sets beam and gas parameters using an optimal flux balance stored in advance in a data memory. and equipment.

In actual processing of multilayer devices, it is practical to fix the substrate temperature T0 and the ion acceleration voltage v0 to constant conditions, and to perform processing by switching only the etching gas depending on each layer to be processed. At this time, the T. ,V. Under these conditions, the optimum Franks balance Bad of the reaction corresponding to each layer is determined in advance and stored in memory. In this case, flux balance B is optimal. can be obtained in the same manner as in the first and second embodiments described above.

As a result, the flux balance can be easily set to the optimal flux balance read from the memory each time the layer changes, and efficient high-speed processing is always possible.

FIG. 12 shows a flowchart of a processing method corresponding to one layer. First, a combination of a material to be processed and an etching gas corresponding to the layer to be processed is set, and the optimum flux balance Bad for the reaction of that combination is read out from the data memory. At this time, the substrate temperature T0 and the ion acceleration voltage V0 are fixed at constant values. Next, manually set the beam parameters from the keyboard (or automatically set the beam parameters for the next layer to be processed). The gas flux δgms is calculated backward from the 00 formula and obtained as follows.

Furthermore, the gas flow rate Q and the nozzle distance L are calculated from equations (5) and (6) as follows.

L, = f-' (kn)
・Eω The gas parameters Q and Ly obtained as above are output to each control section of the apparatus along with the beam parameters and substrate temperature to start processing.

FIG. 13 shows a configuration diagram of an apparatus for carrying out this embodiment.

An ion beam 1 extracted from an ion source 9 and passed through an electrode 10 is focused onto a sample 21 by a front-stage focusing lens 11 and a rear-stage focusing lens 16.

Beam current 1. can be selected by switching the aperture of the variable aperture aperture 12 using the drive unit 28. Also, the beam can be turned on and off by the planking electrode 13,
When the beam is OFF, the beam is made to enter the Faraday cup 15 provided on the blanking aperture 14, and the beam current I. monitor.

The focused ion beam is irradiated onto a desired area on the sample 21 by the electric field created by the deflector electrode 17, and secondary particles are detected by the secondary particle detector 18 in synchronization with the scanning of the beam.
scope (scanning ion microscope) image. This SIM
The image allows processing position setting and observation. A temperature sensor 22 is attached to the sample 21 to monitor the sample temperature, and a heater 23 and a cooling pipe 24 control the sample temperature. Etching gas from the etching gas cylinder 31 is sprayed onto the surface of the sample 21 from the axially symmetrical nozzle 19 . The gas flow rate is controlled by a flow rate controller 33. Further, the nozzle height is detected by the capacitance sensor 20 and set by the nozzle height setting mechanism 29. Voltage supply to the ion beam optical system and beam control are performed by a focused ion beam power supply control section 34 and a focused ion beam deflection control section 38, respectively. In addition, the board temperature setting,
Gas flow rate setting and nozzle height setting are performed by sample temperature control section 36, gas flow rate control section 35, and nozzle height control section 37, respectively.
This is done by All of these device control units are controlled by the overall control CP.
Operates according to instructions from U39. When implementing the processing method of this embodiment, first, the substrate temperature data and beam parameters are input from the overall control CPU to the sample temperature? The control section 36, the focused ion beam power supply control section 34, and the focused ion beam deflection control section 38 are instructed and set.

Gas parameters are calculated in the overall control CPU from the data of the optimum flux balance B2 read from the data memory 41, and instructions are sent to the gas flow rate control section 35 and the nozzle height control section 37 to start machining.

When processing a multilayer device according to this embodiment, it is necessary to monitor the material to be processed during processing in order to set the optimum flux balance for each layer to be processed. Here, in beam-assisted reactive etching, the reactive substances released from the workpiece during processing include elements of the workpiece layer. Therefore, by conducting elemental analysis of reactive substances,
The material of the layer to be processed can be detected and monitored during processing.

A method for detecting the material to be processed by elemental analysis of reaction products will be explained using FIGS. 16 to 22. FIG. 16 shows a schematic diagram of a workpiece material detection system using light absorption of reactive substances. Light emitted from a light source 45 such as a halogen lamp or a xenon lamp enters a monochromator 46 to extract monochromatic light with a specific wavelength λ. At this time, the monochromator 46 can scan the wavelength λ of the light to be extracted. The monochromatic light is split into two by a beam splinter 47, one of which is focused and irradiated near the surface of the sample 21 by a condensing lens 48, and the intensity of the transmitted light is measured by a detector 5o such as Photomar. The other light from the beam splinter 47 is condensed and irradiated onto the reference cell 49 by the condenser lens 48, and the intensity of the transmitted light is measured by the detector 50. here,
If a substance that absorbs light (a substance whose absorption band corresponds to the wavelength λ of light) exists in the optical path, a portion of the incident light is absorbed by the substance, and the intensity of the transmitted light decreases. Assuming that the concentration of the light-absorbing substance is uniform at 0 and the thickness is d, the absorbance (physical quantity indicating the degree of light absorption) E is defined by the following formula, where the irradiated light intensity is IQ and the transmitted light intensity is ■. .

Emi log (Io/It) = o d e where ε is called the molecular extinction coefficient. While scanning the wavelength λ of the irradiated light, I1 is measured, and the absorbance E is measured? However, this spectrum has peaks specific to the type of light-absorbing substance. Therefore, the light absorbing substance in the optical path can be identified by the spectrum of absorbance E. In FIG. 16, when the ion beam 1 is irradiated to perform local reactive etching, the transmitted light intensity is simultaneously measured by the detector 50, and the absorbance spectrum is measured at regular sampling intervals.

For example, CC! ! Ajl using 4 gases! When processing wiring, Al, Cl. occurs, so
As shown in Figure 17 in the absorbance spectrum, /l Cl6
A peak corresponding to appears. Processing progresses and A15i!
When the line processing is completed, the peak of Al2Cll6 disappears, and the workpiece can be detected.

At this time, the accuracy of the change in the material being processed is determined by the sampling interval of the absorbance spectrum, but if the entire wavelength range is scanned each time, the sampling interval cannot be shortened. Therefore,
AN and Cl6 are sealed in the reference cell 49, and the detector 50
Based on the measured values, AIt z C II
Obtain the wavelength λ at which the peak of b appears. A: During wiring processing, by fixing the wavelength of irradiation light to λ1 and monitoring changes in absorbance E, changes in the material to be processed can be detected in real time. When processing a multilayer device, the wavelengths at which the peaks corresponding to the reaction substances generated during processing of each layer to be processed appear are obtained in advance.

During processing, the layer to be processed at that time is irradiated with light of a corresponding wavelength, and changes in absorbance E are monitored to detect changes in the material to be processed. Once a change in material is detected, the etching gas is switched, the wavelength of the irradiation light is switched to a wavelength corresponding to the next layer to be processed, and the change in absorbance E is continuously monitored to detect the material to be processed.

FIG. 18 shows a schematic diagram of a workpiece material detection system using fluorescent light from reactive substances. The irradiation light generating section is the same as the workpiece material detection system shown in FIG. One of the two beams split by the beam splitter 47 is condensed and irradiated near the surface of the sample 21 by the condensing lens 48, and the intensity of the transmitted light is measured by the detector 52. The intensity of the other light from beam splinter 47 is measured by detector 53. Here, when the reactive substance produced from sample 2■ absorbs the irradiated light,
It emits fluorescent light with a wavelength shifted to the longer wavelength side (lower energy side) from the wavelength of the irradiated light.

While scanning the wavelength λ of the irradiated light, the fluorescence intensity 1, is measured by the detector 5I to obtain an excitation fluorescence spectrum, which has a peak unique to the substance that emits fluorescence. Therefore, the substance in the optical path can be identified by the peak of the excitation fluorescence spectrum. Here, since the intensity of the irradiated light changes depending on the wavelength, the intensity of the irradiated light is measured by the detector 51. The ratio of fluorescence intensity If to 1f/I
．． It is preferable to obtain a spectrum by In FIG. 18, when the ion beam 1 is irradiated to perform local reactive etching, the fluorescence intensity is simultaneously measured by the detector 5l, and the excited fluorescence spectrum is measured at regular sampling intervals. For example, CCI. When processing Al wiring using gas, A 12 z C I is used as a reactant.
Because t a occurs, the 19th
As shown in the figure, a peak corresponding to AllzCl6 appears. As the processing progresses and the processing of the Al wiring is completed, the Al,
The peak of Cl disappears, and changes in the material of the workpiece can be detected. At this time, the detection accuracy of changes in the material to be processed is determined by the sampling interval of the excitation fluorescence spectrum, but if the entire wavelength range is scanned each time, the sampling interval cannot be shortened. Therefore, AA is processed by trial processing to obtain in advance the wavelength λ1 at which the peak of Alt2Cl6 appears in the excitation fluorescence spectrum. When processing the A1 wiring, by fixing the wavelength of the irradiated light to C and monitoring changes in the fluorescence intensity, it is possible to detect changes in the material to be processed in real time.

Also, at this time, the wavelength of fluorescence from All2Cl is measured. In fluorescence detection, in order to avoid the influence of scattered light of irradiated light, fluorescence is made incident on the detector 51 through a filter 54 that passes only a wavelength band near λ2.

When processing a multilayer LSI, the wavelength of the irradiation light at which a peak corresponding to each reaction substance that occurs when processing each layer to be processed appears is obtained in advance.

During processing, light of a wavelength corresponding to the layer to be processed at that time is irradiated, changes in the fluorescence intensity I, are monitored, and changes in the material to be processed are detected. When a change in material is detected, the reactive gas is switched, the wavelength of the irradiation light is switched to the wavelength corresponding to the next layer to be processed, and the fluorescent light intensity is continuously increased.
, and detects the material to be machined. At this time, since the wavelength band of the fluorescent light also changes, the filter switching mechanism 55 is used to switch to a filter that passes the fluorescent light corresponding to the reactive organic material in the layer to be processed. Note that the detection sensitivity of fluorescence is much higher than that of absorption measurement, and the detection accuracy of changes in the material to be processed is improved by using fluorescence intensity 1, rather than by using absorbance E.

FIG. 20 shows a schematic diagram of a workpiece material detection system using absorption of characteristic X-rays. The characteristic X-rays emitted from the X-ray tube 56 are sent to sample 2.
1, and the intensity of the X-rays passed through the reference chamber 57 from above the sample is passed through a filter to the detector 58.
Measure with. For example, when processing A6 wiring using CCa gas, Aβ2(1!,) is produced as a reaction product. If AffOKa ray is used as the irradiation X-ray, A1
2 z C Itb is efficient <absorbs Ka line of AE,
The transmitted X-ray intensity decreases. As the processing progresses and the processing of the Al wiring is completed, the transmitted X-ray intensity increases and changes in the material of the processed material can be detected. Here, a known amount of Al z C 1 b is introduced into the reference chamber 57,
By measuring the change in the transmitted X'fIIA intensity, the amount of A12Ca6 produced during processing can be quantitatively evaluated. When processing multilayer devices, each reaction product generated during processing of each processed layer is efficiently
It is necessary to switch the wavelength of the irradiated X-rays so that the radiation is absorbed. For this purpose, there are several methods of providing and switching between multiple types of X-ray tubes 56, rare gas continuous light sources, synchrotron radiation (
There is a method of extracting a desired wavelength from a continuous wavelength light source such as SOR using a filter or the like.

FIG. 21 shows a schematic diagram of a workpiece material detection system using reaction product ions. The X-ray generation section and irradiation section are located at the 20th
Although it is similar to the workpiece material detection system shown in the figure, a short wavelength light source such as an ultraviolet laser may be used. During the local reactive etching of the present invention, when the reactant is irradiated with X-rays of sufficient intensity,
Reactive substances absorb X-rays and dissociate into ions. By analyzing these ions, the material of the layer to be processed at that time can be detected. For example, when processing A1 wiring using CCZ gas, A1 is used as a reactive substance.
z C l i, occurs. When AIKa rays of sufficient intensity are irradiated from the X-ray tube 56, A 1 z C l! b
is AI! " and Cl- dissociate. Cl- collides with each other and with the flux of CCIl and gas, and most of them recombine and become molecular. On the other hand, A15 remains relatively stable in its ionic state.

Al
"゜ is pulled in and introduced into the mass spectrometer 60 to detect the ion intensity. As the processing progresses and the processing of the A1 wiring is completed,
The ion strength of Al"+ disappears, and changes in the material being processed can be detected. When processing multilayer devices,
It is necessary to switch the wavelength of the irradiated X-rays so that each reaction product generated during processing of each layer to be processed efficiently absorbs the X-rays. Regarding this point, the X-ray irradiation section is provided with wavelength selectivity, similar to the workpiece material detection system shown in FIG. In addition, since the ion species generated by the dissociation of the reaction product also change, it is necessary to successively adjust the detection mass number of the mass spectrometer 60, which is a detector, to the ion species to be detected.

FIG. 22 shows a schematic diagram of a processing material detection system using photoelectron spectroscopy for reactive substances. Excitation light emitted from a short wavelength light source 56 such as an X-ray tube or an ultraviolet laser is applied to the sample 21.
irradiates near the surface of the During the local reactive etching of the present invention, the reaction product has a sufficiently short wavelength (photon energy h
When irradiated with excitation light (with a large value of v), photoelectrons are emitted from the reaction product. By analyzing the energy of these photoelectrons, it is possible to detect the type of reactant and the material of the layer to be processed at that time. For example, CC14
When processing Aj2 wiring using gas, A6. Cj26 occurs. Excitation light is irradiated from a light source 56, and photoelectrons emitted from AA2 (lh) are drawn in by a photoelectron drawing optical system 61 using an electron lens group, introduced into an energy analyzer 62, and a photoelectron intensity is detected by a detector 63. At this time, Af2Cj26 can be identified from the energy of the detected photoelectrons (the energy set for the energy analyzer 62 through which the photoelectrons pass).As the machining progresses and the machining of the Aj2 wiring is completed, A l z
The photoelectronic signal from C l b disappears and changes in the material to be processed can be detected. When processing a multilayer device, by making the wavelength of the excitation light sufficiently short, it can be commonly used as excitation light for detecting the material of the workpiece when processing all the layers to be processed. On the other hand, the energy setting of the energy analyzer 62 needs to be changed sequentially depending on the type of reaction product occurring at that time.

As explained above using FIGS. 16 to 22, the material to be processed can be detected by detecting the reaction product. In this example, detection was performed by applying energy to the reactive substance from the outside, but the reactive substance was excited by the energy of the reaction itself, and the excess energy was emitted in the form of fluorescence, photoelectrons, etc. It is also possible to detect the material being processed. It is also possible to detect the material to be processed by detecting atoms and ions that are physically sputtered during processing. By detecting the material to be machined using one of the methods described above and setting the optimal flank balance in response to changes in material,
Efficient and high-speed machining is always possible.

(Example 4) In Examples 1 and 2.3 described above, examples using focused ion beam irradiation and gas supply using a nozzle were explained. The present invention can be carried out in exactly the same manner even when using . In this Example 4, Example 3
A processing method and apparatus will be described in which the gas supply method is replaced with a method using a subchamber.

FIG. 14 shows a flowchart of the processing method of this embodiment. First, the combination of the material to be processed and the etching gas corresponding to the layer to be processed is set, and the optimum flux balance Bad for the reaction of that combination is determined. read from data memory. At this time, the substrate temperature T0 and the ion acceleration voltage v0 are constant. Enter beam parameters from the keyboard (
Alternatively, the beam parameters for the next layer to be processed are automatically set. Calculate the gas flux δ9■ from the αω formula. Furthermore, the subchamber internal gas pressure P is calculated from equation (8) as follows.

C-N. The obtained gas pressure P is output to each control section of the apparatus together with the beam parameters and substrate temperature, and processing is started.

FIG. 15 shows a diagram of the apparatus configuration of this embodiment. The only difference from the device of Example 3 is the gas supply section.

The etching gas from the etching gas cylinder 31 fills the subchamber 42 containing the sample 21.

The etching gas pressure P is detected by a gas pressure gauge 43,
It is controlled by a gas flow rate controller 33.

This etching gas pressure detection control is performed by the gas pressure control section 44. When implementing the processing method of this embodiment, first, the overall control CPU instructs substrate temperature data and beam parameters to the sample temperature control section 36, focused ion beam power supply control section 34, and focused ion beam deflection control section 38. Set. From the data of the optimum flux balance Bad read from the data memory 4l, the overall control CPU
The gas pressure P is calculated within the unit, and an instruction is sent to the gas pressure control unit 44 to start machining.

〔Effect of the invention〕

As explained above, when energy beam assisted reactive etching is performed by applying the energy beam processing method according to the present invention using the energy beam processing apparatus according to the present invention, the combination of the etching gas and the material to be processed, the energy beam Even if the energy of the sample changes or the temperature of the sample changes, the etching gas irradiation amount and the energy beam irradiation amount can be controlled to an optimal balance, so high-speed processing can always be performed with high efficiency, which is an excellent practical effect.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the processing method of Example 1 of the present invention, FIG. 2 is an explanatory diagram of beam parameters in focused ion beam irradiation, FIG. 3 is an explanatory diagram of beam parameters in shower ion beam irradiation, and FIG. 4 is an explanatory diagram of beam parameters in shower ion beam irradiation. The figure is an explanatory diagram of gas parameters in etching gas supply using a nozzle, Figure 5 is an explanatory diagram of gas parameters in etching gas supply using a subchamber, and Figure 6 is an explanatory diagram of gas parameters in focused ion beam assisted reactive etching. FIG. 7 is a chart showing the time change of ion flux. FIG. 7 is a chart showing the time change of gas flank and ion flux in shower ion beam assisted reactive etching. FIG. 8 is an explanatory diagram of the trial processing method of Example 1. The figure is a chart showing an example of the trial processing results of Example 1.
Figure 0 is a flowchart showing the processing method of Example 2 of the present invention, Figure 11 is an explanatory diagram of the method of calculating the maximum processing area per l ion in Example 2, and Figure 12 is Example 3 of the present invention.
Flowchart showing the processing method of FIG. 13 is Example 3
FIG. 14 is a flowchart showing the processing method of the fourth embodiment of the present invention, and FIG. 15 is a diagram of the device configuration of the fourth embodiment. Figure 16 is a diagram explaining the principle of detecting workpiece materials using light absorption of reaction products, Figure 17 is a chart showing an example of the absorption spectrum of reaction products, and Figure 18 is the fluorescence of reaction products. Figure 19 is a diagram showing an example of the fluorescence spectrum of a reactive substance, Figure 20 is a diagram explaining the principle of detecting a workpiece material using absorption of characteristic X-rays. , FIG. 21 is a diagram explaining the principle of detecting the material to be processed using reaction product ions, and FIG. 22 is a diagram explaining the principle of detecting the material to be processed using photoelectron spectroscopy for the reaction product. DESCRIPTION OF SYMBOLS 1... Ion beam, 2... Processing area, 3... Sample, 4... Chamber, 5... Gas nozzle, 6...
Gas chamber, 7... Subchamber, 8... Incident ion, 9... Ion source, 10... Extraction electrode, 1
DESCRIPTION OF SYMBOLS 1... Front stage focusing lens, 12... Variable diameter aperture, 13... Blanking electrode, 14... Blanking aperture, 15... Faraday cup, I6.
...Later focusing lens, 17...Deflector electrode, 18
...Secondary particle detector, 19...Axisymmetric gas nozzle, 20...Capacitance sensor, 21...Sample, 22
...Temperature sensor, 23...Heater, 24...Cooling pipe, 25...Insulating material, 26...Chamber, 27...
・Magnetic seal, 28...variable aperture drive unit,
29... Nozzle height setting mechanism, 30... Chamber,
31... Etching gas cylinder, 32a. 32b...
- Valve, 33...Flow rate controller, 34...Focused ion beam power supply control section, 35...Gas flow rate control section, 36...Sample temperature control section, 37...Nozzle height control section, 38 ...Focused ion beam deflection control section, 39.
...Overall control CPU, 40...Keyboard, 41...
・Data memory, 42...Subchamber, 43...
Gas pressure gauge, 44... Gas pressure control unit, 45... Light source, 46... Monochromator, 47... Beam splitter 48... Condensing lens, 49... Reference cell,
50. 51, 52. 53...Detector, 54
... filter, 55 ... filter switching mechanism, 56.
...X-ray source (ultraviolet light source), 57...Reference gas chamber, 58...Detector, 5...Ion attraction optical system, 60...Mass spectrometer, 61...Photoelectron attraction optical system , 62... Energy analyzer, 63... Detector.

Claims (11)

[Claims] 1. In this method, the workpiece is irradiated with an energy beam in an etching gas atmosphere, and reactive etching is performed locally at the irradiated area of the energy beam.The ratio between the amount of etching gas supplied and the amount of energy beam irradiation is controlled to achieve the highest efficiency. An energy beam processing method characterized by achieving an optimal balance in which etching gas molecules and workpiece atoms react well. 2. When finding the optimal balance mentioned above, the combination of the workpiece material and etching gas, the energy of the energy beam, and the temperature of the workpiece are set to the same conditions as in actual processing, and the etching gas supply amount and energy beam irradiation amount are The energy beam according to claim 1, characterized in that trial processing is performed while changing the ratio of the etching gas supply amount and the energy beam irradiation amount to find the optimum balance between the etching gas supply amount and the energy beam irradiation amount from the conditions that maximize the processing yield. Processing method. 3. When finding the optimal balance described above, the combination of the workpiece material and etching gas, the energy of the energy beam, and the temperature of the workpiece are set to the same conditions as in actual processing, and one incident particle of the energy beam is The energy distribution applied to the surface of the object is determined by simulation, and from the determined energy distribution, the number of workpiece atoms that will react with the etching gas molecules is determined with a sufficient probability. 2. The energy beam processing method according to claim 1, wherein the optimum balance between the etching gas supply amount and the energy beam irradiation amount is determined from the conditions for supplying the etching gas molecules. 4. When processing a multilayer device, the energy of the energy beam and the temperature of the workpiece are fixed to constant conditions, and the amount of etching gas supplied and the amount of energy beam irradiation are determined in advance for each combination of the material of the layer to be processed and the etching gas. During actual processing, the etching gas is switched and supplied according to the material to the successive layers to be processed, and the etching gas supply amount and energy beam irradiation are adjusted accordingly. 2. The energy beam processing method according to claim 1, wherein the ratio of the amount to the amount is controlled so as to obtain an optimal balance read out from a memory sequentially. 5. It consists of an energy beam source, a focusing optical system, a stage, a secondary particle detector, an etching gas supply means, a substrate temperature control means, and a power controller that drives them, and irradiates the workpiece with an energy beam in an etching gas atmosphere. An energy beam processing device that locally performs reactive etching includes a means for detecting the material of the workpiece, a means for setting the etching gas type, energy beam energy, and substrate temperature, and a method for detecting the detected workpiece. means for controlling the ratio of the etching gas supply amount to the energy beam irradiation amount based on the material of the material, the set etching gas type, the set energy beam energy, and the set substrate temperature conditions. Features: Energy beam processing equipment. 6. The means for detecting the material of the workpiece includes a wavelength-variable monochromatic light irradiation means consisting of a light source and a monochromator, and an intensity detection method of the light irradiated near the sample from the monochromatic light irradiation means and passed through. 6. The energy beam processing apparatus according to claim 5, further comprising means for detecting. 7. The means for detecting the material of the workpiece includes a wavelength-tunable monochromatic light irradiation means consisting of a light source and a monochromator, and detecting the intensity of fluorescent light generated from near the sample when irradiated with the monochromatic light. characterized by being equipped with a means to
The energy beam processing device according to claim 5. 8. The means for detecting the material of the workpiece comprises an X-ray source and means for detecting the intensity of the X-rays emitted from the X-ray source to the vicinity of the sample and passing through. 5. The energy beam processing device according to 5. 9. 5. The means for detecting the material of the workpiece comprises an X-ray source and means for detecting workpiece ions generated by the X-rays irradiated from the X-ray source. The energy beam processing device described in . 10. 6. The energy beam processing apparatus according to claim 5, wherein the means for detecting the material of the workpiece uses a photoelectric spectrometer. 11. 6. The energy beam processing apparatus according to claim 5, wherein the means for detecting the material of the workpiece uses a mass spectrometer.