JP2881053B2 - Energy beam local processing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local processing or local film forming technique, and more particularly, to a method of irradiating a sample with an energy beam in an etching gas atmosphere and inducing a chemical reaction in an irradiated portion to perform local etching. And a device for implementing it.

[0002]

2. Description of the Related Art An ion beam or an electron beam is 0.1 μm.
Focusing is possible below, and fine processing and local CVD can be performed using the energy. In recent years, research on practical use of photomask repair devices and LSI wiring repair devices using focused energy beams has been actively pursued.

It has been known that by supplying an etching gas to a sample surface simultaneously with irradiation of a focused energy beam, reactive etching is locally induced at a beam irradiation portion, and high-speed and high-selection fine processing is possible. I have. Incidentally, as a device related to this type of device, for example,
No. 129256 is cited.

[0004]

In the above-described energy beam local etching apparatus of the prior art, a single kind of etching gas is generally used as an etching gas. However, among the etching gases, there is a gas in which the reaction proceeds spontaneously and isotopically with the material to be processed, and side etching to the side is inevitable. Conversely, even if an etching gas used in a high-energy plasma state in ordinary dry etching is used for local etching of an energy beam, the etching gas itself has a low energy in a molecular state, and the energy given by the energy beam is insufficient. Often does not occur. That is,
With a single etching gas, the reaction is too violent or almost no reaction occurs, so that accurate high-speed processing cannot be expected.

For example, when processing Al, if Cl ₂ is used as an etching gas, a spontaneous reaction is intense and large side etching occurs. On the other hand, if SiCl ₄ or BCl ₃ is used as an etching gas, almost no local reaction occurs. There is no single etching gas that shows an appropriate reaction.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned conventional problems, and a single etching gas causes an excessively strong reaction or almost no reaction. An object of the present invention is to provide an improved energy beam local processing method that can easily control the reactivity of a material that cannot be used, and an apparatus for implementing the method.

[0007]

An object of the present invention is to provide an energy beam local etching method using, as an etching gas, a gas obtained by mixing an etching gas which is too intense and generates a spontaneous reaction with another etching gas having low reactivity. And at that time controlling the mixture ratio of the mixed gas to an arbitrary value.

Another object of the present invention is to perform an energy beam local treatment using a mixed gas of an etching gas and a CVD gas, which reacts too vigorously and generates a spontaneous reaction. It is also achieved by controlling the value. The CVD gas is a gas used when depositing a predetermined substance by a known chemical vapor deposition.

[0009]

The present inventors have conducted various experimental studies on the composition of the workpiece and the mixed gas, and have obtained the following examples. That is, for the processed material Al, a mixed gas of Cl ₂ and SiCl ₄ as the etching gas, Cl ₂
And the sample temperature were changed, and local etching was attempted at the irradiation part of the Ga ion beam. The result is shown in FIG. When the sample temperature is constant, the processing speed increases as the Cl ₂ mixture ratio increases, and side etching occurs gradually at a certain mixture ratio or higher. That is, it can be seen from this figure that the side etching occurs, for example, when the sample temperature is 200 ° C., when Cl _{2 is} 5% or more.

In addition, when the mixing ratio is constant, the processing speed and the side etch amount increase as the sample temperature increases. Therefore, it can be understood that the reactivity can be controlled by controlling the Cl ₂ mixing ratio and the sample temperature. For example, it is possible to perform sufficiently high-speed processing in which a side etching does not occur in a region having a small Cl ₂ mixing ratio, and it is also possible to intentionally generate side etching in a region having a large Cl ₂ mixing ratio and a high sample temperature. .

[0011] Then with respect to the processed material Al, a mixed gas of Cl ₂ and Si (OC ₂ H _{5) 4} as a process gas, by varying the mixing ratio and sample temperature of Cl _2, irradiation of the Ga ion beam FIG. 3 shows the result of trying local processing in the section. Processing unit side mixing ratio in with increasing Cl ₂ mixture ratio as a boundary is Si
The process shifts from deposition of SiO ₂ due to decomposition of (OC ₂ H ₅ ) ₄ to side etching with Cl ₂ . For example, a sample temperature of 200
It can be seen that in the case of ° C, the deposition shifts from SiO ₂ to side etching when Cl _{2 is} 10% or more. Also, the side etching amount increases as the sample temperature increases.
Therefore, it can be understood that by controlling the Cl ₂ mixing ratio and the sample temperature, the amount of SiO ₂ deposited on the side surface of the processed portion and the amount of side etching, that is, the reactivity can be easily controlled.

These experimental results are the same even when the material to be processed is changed from Al to Si or GaAs, for example. Also,
The energy beam is not limited to Ga ions, and other well-known ion beams, electron beams, and laser beams can also be used.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, a case where an ion beam is used as an energy beam will be described, but the same can be applied to a case where an electron beam is used.

Embodiment 1 As a first embodiment of the present invention, an example using a mixed gas of a spontaneous etching gas and another etching gas will be described. FIG. 1 shows the principle. As described with reference to FIG. 2 in the operation section, the reactivity can be controlled by the mixture ratio of the spontaneous etching gas and the other etching gas and the sample temperature. The example shown in FIG. 1 is for Cl ₂ and SiCl ₄
The ion beam 1 is irradiated in a mixed gas atmosphere, SiO ₂
This is an example in which the Al layer 4 is processed through the insulating layer 3. At this time the sample temperature was fixed at 200 ° C., Cl ₂ as shown in FIG. 1 (a)
If the mixing ratio is 20%, the specific side etching amount
(In this case, about 0.25 μm / s), the side etching amount can be intentionally set within a range where damage such as disconnection does not occur on the side. Furthermore, the Cl ₂ mixing ratio as shown in FIG. 1 (b) 3%
In this case, processing can be performed without generating side etching. As described above, by controlling the mixing ratio of Cl ₂ which is a spontaneous etching gas, side etching can be prevented or intentionally generated, and the amount of side etching to be generated can be set.

FIG. 4 shows the configuration of the apparatus according to the present embodiment. In the figure, an ion beam 1 extracted from an ion source 5 by an extraction electrode 6 is focused on a sample 13 by a former focusing lens 7 and a latter focusing lens 11. At this time, the current of the ion beam is controlled by the opening diameter of the beam limiting aperture 8. Then, the trajectory of the beam is bent by the blanking electrode 9 and the beam is cut off by the blanking aperture 10, thereby controlling on / off of the beam. Further, the focused ion beam is deflected by the dellector electrode 12, and the beam is irradiated to a desired region on the sample. When processing Al, gas cylinder 14a
The SiCl ₄ and Cl ₂ from the gas cylinder 14b from the buffer chamber 15a, respectively, 15b and flow control valves 17a, 17b
And the mixture is supplied to the surface of the sample 13 through the gas nozzle 18a. At this time, the mixing ratio of the mixed gas is controlled by the flow ratio of each gas, but the gas flow is controlled by the pressure of the buffer chambers 15a and 15b and the flow control valve 17a.
a, 17b Set by conductance.

A gas cylinder 14C, a buffer chamber 15C, and a flow control valve 17 are provided as a supply system of an etching gas XeF ₂ used for processing an SiO ₂ insulating layer, which is another material to be processed.
C and a gas nozzle 18b. Simultaneously with the supply of the etching gas, the sample 13 is irradiated with a focused ion beam to perform beam local etching. At this time, a product generated by the reaction is detected by the reaction product detector 19, and the material to be processed and the etching rate are monitored. As the reaction product detector 19, a mass analyzer (quadrupole type, sector magnetic field type, etc.) or a spectroscopic analyzer (fluorescence detector, photoelectron spectrometer, etc.) may be used. Sample temperature during processing is stage 2
The temperature is monitored by a thermocouple 21 provided in 0, and controlled by a heater 22 and a cooling pipe 23.

Next, an example of the processing method according to the present embodiment will be described with reference to FIG. As shown in the figure, this is an example in which the lower wiring 32 is cut at the overlapping part of the two-layer wirings 31 and 33 of the LSI. There is a risk of re-adhering to the side wall of the hole and causing short circuit failure between the upper and lower wirings. Therefore,
This embodiment utilizes the fact that the reactivity during Al processing, that is, the amount of side etching can be controlled. First, FIG.
After processing the SiO ₂ protective film 30 using the XeF ₂ gas 29 as shown in FIG. ₂ , Cl ₂ (20%) and SiCl ₄ (80) are formed as shown in FIG.
%), The upper wiring 31 is processed by generating an appropriate amount of side etching that does not cause disconnection. After processing the interlayer insulating film 32 by using XeF ₂ gas 29 as shown in FIG. 2 (c) Subsequently, as shown in FIG. (D) Cl ₂ (3
%) And SiCl ₄ (97%) using a mixed gas 2 ′ to cut the lower wiring 33 while preventing side etching. As described above, the short circuit of the upper and lower wirings can be prevented by the side etching of the upper wiring 31, and the processing can be performed while minimizing the damage of the upper and lower wirings.

Embodiment 2 As a second embodiment of the present invention, an example using a mixed gas of a spontaneous etching gas and a CVD gas will be described. As described with reference to FIG. 3, the reactivity can be controlled by the mixture ratio of the spontaneous etching gas and the CVD gas and the sample temperature. The device configuration of this embodiment is the same as that of the first embodiment.
And the etching gas SiCl ₄
It uses a CVD gas Si (OC ₂ H ₅ ) ₄ for SiO ₂ film formation.

According to this embodiment, the spontaneous etching gas Cl ₂
For example, when a cutting process similar to that in the example of FIG. 5 is performed using a mixed gas of CVD gas Si (OC ₂ H ₅ ) ₄ and SiO 2, the side surface of the cutting portion of the lower wiring 33 is formed at the stage of FIG. _Two films can be deposited, and the reliability of cutting can be improved.

<Embodiment 3> As a third embodiment of the present invention, an example will be described in which processing using a mixed gas of a spontaneous etching gas and another etching gas and CVD of a gold layer film are successively performed. As in the first embodiment, the reactivity at the time of processing is controlled by the mixture ratio of the mixed gas and the sample temperature. FIG. 6 shows the configuration of the apparatus of this embodiment. During Al processing, Cl ₂ is supplied from the gas cylinder 14a, and SiCl is supplied from the gas cylinder 14b.
₄ were mixed at a flow ratio (i.e., a mixing ratio) set by the mask low controllers 35a and 35b, respectively, and the gas nozzle
It is supplied to the surface of the sample 13 through 18a. A gas cylinder 14c, a mask low controller 35c, and a gas nozzle 18 serve as a supply system of the CVD gas W (CO) ₆ used for forming the metal film W.
b is provided. Since W (CO) ₆ is a sublimable crystal, the sample temperature during processing or film formation of the entire CVD gas supply system by a heater (not shown) is monitored by an infrared thermometer 36, and the laser irradiation heating unit and It is controlled by the cooling pipe 23. Here, the laser irradiation heating unit is a laser oscillator 37,
It comprises an objective lens 38 and a reflecting mirror 39. The other components and functions thereof except for the gas supply system and the sample temperature control system are the same as those of the apparatus of the first embodiment.

Next, an example of the local processing method according to the present embodiment will be described with reference to FIG. As shown in FIG.
At the overlapping part of the layer wirings 31 and 33, the metal film CV
This is an example in which a signal detection pad is drawn out by D. If a contact hole is simply formed in the lower layer wiring 33 through the upper layer wiring 31 and the metal film is drawn out, the upper and lower wirings are short-circuited by the formed metal film, and no signal can be taken out. Therefore, first, the SiO ₂ protective film 30 is processed by ion beam sputtering as shown in FIG. 3A, and then Cl ₂ (20%) and SiCl ₂ are formed as shown in FIG.
_{Using 4} (80%) of the mixed gas 2, an appropriate amount of side etching is generated to process the upper wiring 31. The same figure
As shown in (c), the interlayer insulating film 32 is processed by using a sputtering process to expose the lower wiring 33, and as shown in FIG.
Using a (CO) ₆ CVD gas, a metal W film is extracted from the lower wiring 33 to form a signal detection pad 43.

As described above, the short-circuit of the metal W film is prevented by forming the film by using the side etching of the upper wiring, and the signal detection pad from the lower wiring 33 can be formed simply and reliably. At this time, the optimum sample temperature is different between the time of processing the upper wiring 31 and the time of forming the W film. However, when the apparatus of this embodiment is used, the sample temperature can be quickly controlled by turning on and off the heating laser. It can be carried out.

[0023]

According to the present invention, when an energy beam is irradiated in a processing gas atmosphere and a beam local processing, particularly a beam local etching, is performed, a mixed gas of an etching gas causing a spontaneous reaction and another processing gas is used. Since the mixing ratio of the mixed gas and the temperature of the portion to be processed can be arbitrarily controlled, it is impossible to perform appropriate beam local etching because a single etching gas is too intense or hardly reacts. There is also an effect that the reactivity of the energy beam local etching can be easily controlled for the material.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of a first embodiment of the present invention.

FIG. 2 is an explanatory view showing the operation of the achievement means of the present invention.

FIG. 3 is an explanatory view showing the operation of the achievement means of the present invention.

FIG. 4 is a configuration diagram of an apparatus according to the first embodiment.

FIG. 5 is an explanatory diagram illustrating an example of a processing method according to the first embodiment.

FIG. 6 is a configuration diagram of an apparatus according to a third embodiment.

FIG. 7 is an explanatory diagram illustrating an example of a processing method according to a third embodiment.

[Explanation of symbols]

1 ... Ion beam, 2,2 '... Cl
₂ and SiCl ₄ mixed gas, 3 ... protective film,
4 ... Al layer, 5 ... ion source,
6 ... extraction electrode, 7 ... front-stage focusing lens, 8 ... beam limiting aperture, 9
... blanking electrode, 10 ... blanking aperture,
11: Post-focus lens, 12: Deflector electrode, 13: Sample, 14: Gas cylinder, 15: Buffer chamber, 16: Pressure gauge, 17 ...
Flow control valve, 18 ... gas nozzle,
19 ... reaction product detector, 20 ... stage,
21 ... thermocouple, 22 ... heater,
23… Cooling pipe, 24… Gas supply controller, 25… Sample temperature measuring instrument, 26… Sample temperature controller, 27…
Reacting organism monitor controller, 28: Overall control controller, 29: XeF ₂ gas, 30: SiO ₂ protective film, 31: Upper wiring, 32: Interlayer insulating film,
33… Lower wiring, 35… Mass flow controller, 36… Infrared thermometer, 37… Laser oscillator, 40… Sample temperature measuring instrument, 41… Laser controller, 42…
W (CO) ₆ , 43 ... W deposited film.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/30 502W

Claims (6)

(57) [Claims] In an energy beam local processing method for irradiating a sample with an energy beam in a processing gas atmosphere and locally performing energy beam processing at an energy beam irradiation unit, a mixed gas is used as the processing gas. The method according to any one of claims 1 to 3, wherein the at least one component gas comprises a spontaneous etching gas that spontaneously and isotropically etches the material of the sample. 2. The method according to claim 1, wherein the mixed gas used as the processing gas is a mixed gas of a plurality of etching gases, at least one of which is the spontaneous etching gas, Is an etching gas in which a reaction occurs only in the irradiated portion of the energy beam, and by controlling the mixing ratio of the spontaneous etching gas, the side etching amount of the processed portion of the sample is controlled to zero or a specific amount. Energy beam local processing method configured as described above. 3. The method according to claim 1, wherein the mixed gas used as the processing gas comprises a mixed gas of the spontaneous etching gas and the CVD gas, and controls a mixing ratio of the spontaneous etching gas. Thereby controlling the amount of side etching or the amount of side deposition of the processed portion of the sample. 4. An energy beam source, a focusing optical system, a stage, a processing gas supply means, a power supply and a controller for driving them, and an energy beam is irradiated to a sample in a processing gas atmosphere to locally generate an energy beam. In the energy beam local processing device that performs the processing,
At least a part of the processing gas supply means is a means for mixing and supplying a spontaneous etch gas for spontaneously and isotropically etching the material of the sample and another processing gas, and the supply means and the controller are An energy beam local processing apparatus having a function of controlling a mixing ratio of a spontaneous etching gas. 5. The energy beam local processing apparatus according to claim 4, wherein the means for mixing and supplying the processing gas comprises:
An energy beam local processing apparatus comprising means for mixing and supplying the spontaneous etching gas and another etching gas which causes a reaction only in the energy beam irradiation section. 6. An energy beam local processing apparatus according to claim 4, wherein the means for mixing and supplying the processing gas comprises means for mixing and supplying the spontaneous etching gas and the CVD gas. Local processing unit.