JP3050579B2 - Cleaning method and device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method and an apparatus for efficiently removing dust adhering to a substrate without using a solution when manufacturing a semiconductor device. Things.

[Prior Art] In the manufacture of semiconductor devices, when dust adheres to the surface of a substrate, this causes a defect in a pattern. As a result, the manufactured semiconductor device is regarded as defective. You can get it. More specifically, in the recent manufacture of semiconductor devices, dry etching such as plasma etching, sputter deposition, and CVD deposition is often used for etching and film formation. By the way, as a problem in such a dry process, adhesion of dust to a substrate has been mentioned. This is because if dust adheres to the substrate before and after the etching process or the film forming process, a defect occurs in a circuit pattern or a film of the semiconductor device, and the device cannot function as a device.

For this reason, a cleaning process using a solution and a drying process have been performed before and after the etching and the film formation in order to remove the attached dust. As described above, the cleaning technology for removing dust is extremely important in manufacturing a semiconductor device. However, as a known dust removing method, a “cleaning technology for the 0.8 to 0.5 μm era” ( '90 latest semiconductor process technology, Semiconductor
As described in the World Press Journal (November 1989, pp. 201-206), wet cleaning such as a method of immersing a substrate in a solution containing a combination of hydrofluoric acid, ammonia, and hydrochloric acid, and a method of applying ultrasonic waves thereto Besides, photo-excited cleaning and dry cleaning using a reactive gas are known.

[Problems to be Solved by the Invention] However, in the case of the conventional technology, when manufacturing a semiconductor device, the etching process and the film forming process are performed in a vacuum, whereas the cleaning process is performed in the air. Therefore, there is a possibility that foreign matter may adhere to the vacuum device after the cleaning process. In addition to such inconveniences, a cleaning process as a non-dry process is required, and the number of processes is unavoidable.

On the other hand, in the cleaning by the dry process method according to the related art, it is possible to perform etching cleaning on the entire substrate surface, but it is not possible to selectively etch only dust, and therefore, by combining with cleaning treatment using a solution. , Dust must be removed.

An object of the present invention is to provide a cleaning method capable of selectively removing dust adhering to a substrate by only a dry process type cleaning, and still another object of the present invention is to provide an apparatus capable of performing such cleaning. It is in.

[Means for Solving the Problems] The object of the present invention is to provide a substrate placed in an excited reactive gas atmosphere in order to remove dust by reacting the dust with the reactive gas in a vacuum atmosphere. On the other hand, by supplying energy so that the temperature rise of the dust attached to the substrate becomes larger than that of the substrate, the dust is vaporized by a selective reaction with the reactive gas. .

Another object of the present invention is to reduce the amount of dust adhering to a substrate in a vacuum processing chamber by reacting the dust with the excited reactive gas and then removing the gas by vaporization. This is achieved by providing at least a means for placing and setting the substrate, a means for supplying energy to the substrate, and a means for setting the temperature rise of the dust attached to the substrate to be greater than that of the substrate. .

[Operation] The point is that in a vacuum atmosphere, by adopting an appropriate energy supply method and a cooling method, the temperature of the dust attached on the substrate is greatly increased as compared with that of the substrate. Then, only the dust is reacted with a reactive gas or an etching gas as a reactive gas in an excited state, and is then selectively removed by vaporization. As a result, the cleaning by the dry process method can be performed, and the cleaning process as well as the etching / film forming process is performed by the dry process method, so that the semiconductor device can be manufactured by a consistent dry process process.

[Example] Hereinafter, the present invention will be described with reference to FIG. 1 and FIG.

FIGS. 1 and 2 show cross sections of an embodiment of the cleaning device according to the present invention.

First, the cleaning device shown in FIG. 1 will be described. In this example, the cleaning device includes a (vacuum) processing chamber, a stage section, an excitation section, a laser beam unit, and a lamp heater unit. . First, as shown in the drawing, the processing chamber 1, which includes a quartz ring window 2 as a part, is evacuated by a vacuum pump (not shown) through an exhaust port 4. ,
The inside is in a vacuum atmosphere. A stage 5 as a stage unit is also provided in the processing chamber 1.
The substrate 6 to be processed is placed on the upper surface of the stage 5 by a holding mechanism 7. Refrigerant pipes 8a and 8b are also provided inside the stage 5, and the stage 5 is cooled by circulating the refrigerant from the refrigerator 9 therein. Further, a gas supply pipe is provided in the center of the stage 5.
A helium gas is supplied from the helium gas source 11 between the upper surface of the stage 5 and the substrate 6 through the gas supply pipe 10 so that the thermal resistance between the stage 5 and the substrate 6 is reduced. Has become. Therefore, when the stage 5 itself is cooled, the substrate 6 itself can also be cooled by the presence of the helium gas. However, at this time, the dust adhered to the upper surface of the substrate 6 is not cooled because no helium gas exists between the dust and the upper surface of the substrate 6, and the temperature rise is not prevented. Has become.

In addition, the excitation unit is an excitation chamber 12, a waveguide 13, a magnetron 1
4. It is composed of an etching gas supply pipe 15 and the like, and the etching gas is excited by a 2.45 GHz microwave from the magnetron 14. That is, the etching gas introduced into the excitation chamber 12 through the etching gas supply pipe 15 from the etching gas source (any one of a plurality of types of etching gas sources can be arbitrarily selected) is excited by the microwave from the waveguide 13. After that, it is introduced into the processing chamber 1. At that time, the waveguide 13
The tuner mechanism provided in the first embodiment makes it possible to achieve matching according to the load condition. Further, a laser beam unit as an energy supply source is configured to include a laser oscillator 16, a mirror 17, and a mirror driving mechanism 18,
The laser beam 19 from the laser oscillator 16 is reflected by the mirror 17 and irradiates the upper surface of the substrate 6 at an angle of 10 ° or less with respect to the upper surface of the substrate 6 so as to scan the upper surface of the substrate 6 through the quartz ring window 2. It has become. If the mirror is appropriately driven by the mirror driving mechanism 18, the entire upper surface of the substrate 6 can be scanned by the laser beam without rotating or moving the substrate 6 itself. Furthermore, the lamp heater 20 as a part of the lamp heater unit, which functions as another energy supply source, can uniformly irradiate the substrate 6 with light or infrared rays from above the substrate 6. It has become.

The cleaning operation performed by the cleaning device configured as described above will be described below.

That is, first, the first cleaning operation will be described. In this case, from the etching gas supply pipe 15,
While F ₂ gas is supplied into the processing chamber 1 via the excitation chamber 12,
The inside of the processing chamber 1 is evacuated through the exhaust port 4 and the internal pressure is maintained at 1 Pa. Incidentally, here, if Pascal (Pa) as a unit of the atmospheric pressure is briefly described, a relationship of 1 atm = 101325 Pa is established between this and atm. The pressure inside the processing chamber 1 is set to such a value.
a, 8b is circulated through the refrigerant at 0 ° C,
The temperature of the stage 5 is maintained at 0 ° C., and at the same time, 100 Pa of He gas is supplied between the substrate 6 and the stage 5, so that the temperature of the substrate 6 itself is also maintained at approximately 0 ° C. ing. Under these conditions, the laser beam
19, the entire surface of the substrate 6 is scanned. Since the laser beam 19 is incident on the substrate 6 at an angle of 10 ° or less, the laser beam 19 itself is almost totally reflected on the upper surface of the substrate 6, and The rise in temperature itself is suppressed. Assuming that the laser beam
Even if 19 is irradiated, since the substrate 6 itself is cooled, the temperature rise in the irradiated part is at most several tens of degrees Celsius.
It can be suppressed to the extent. On the other hand, with respect to the dust attached to the substrate 6, since the dust is surrounded by the vacuum state, the heat conduction to the surrounding is suppressed. As a result, the temperature is rapidly increased by the irradiation of the laser beam 19. It has reached several hundred degrees Celsius. Therefore,
When the dust is Si-based, if F ₂ is used as an etching gas, Si reacts with F, and SiF ₄ as a reaction product can be removed from the surface of the substrate 6 by vaporization. It is. If the dust is a metal, it can be removed by supplying Cl ₂ or HCL gas. If the dust is SiO ₂ or the like, HF gas may be used. However, it has been considered that a mixed gas containing F ₂ , Cl ₂ , HCL, HF, or the like is used as the etching gas. However, depending on the constituents of the dust, a substance that is more difficult to vaporize may be generated. For example, when the dust is Al, chemically stable AlF ₃ is generated by the reaction between Al and F and is not vaporized. Even if Cl is present at that time, the binding energy between Al and Cl is smaller than that of Al and F, and Al cannot react with Cl. In consideration of the above circumstances, in a normal process, a Cl-based gas is first supplied, and then the process is performed.
It has become desirable to supply and process system gases.

Next, the second cleaning operation will be described. In this case, SF ₆ is supplied from the etching gas supply pipe 15.
While the gas is supplied into the processing chamber 1 via the excitation chamber 12, the inside of the processing chamber 1 is exhausted through the exhaust port 4 and the internal pressure thereof is maintained at 1 Pa. At this time, the refrigerant at −170 ° C. is circulated through the refrigerant pipes 8a and 8b, so that the temperature of the stage 5 is maintained at −160 ° C. or lower, and at the same time, 300 P between the substrate 6 and the stage 5.
By supplying the He gas of a, the temperature of the substrate 6 itself is also maintained at about -160 ° C. Furthermore,
In this case, the excitation chamber 12 is also supplied with a microwave of 2.45 GHz from the magnetron 14 via the waveguide 13, and the SF ₆ gas is excited by the microwave to exist as a plasma state. ing. The SF ₆ gas generates chemically active F radicals by being decomposed in the plasma, and the F radicals react with dust in the processing chamber 1.

Now, the lamp heater 20 is turned on in the above state, and the substrate 6
Is irradiated with light and infrared rays, the temperature of the substrate 6 is maintained at about -140 ° C. by the irradiation. This is because the heat incident on the substrate 6 is efficiently transmitted to the stage 5 using He gas as a heat conduction medium. However, as for dust, the temperature rises rapidly for the same reason as described above, and reaches a temperature of -100 ° C or more. If the dust is Si-based and its temperature reaches -130 ° C. or higher, Si reacts with F radicals, and SiF ₄ as a reaction product can be removed from the surface of the substrate 6 by vaporization. is there. However, at this time, since the temperature of the substrate 6 is maintained at −130 ° C. or lower, the substrate 6 itself does not react with F radicals, and only dust is selectively etched. If the dust is like Al, the treatment may be performed with Cl ₂ gas while the temperature of the stage 5 is raised to 0 ° C.

In the second cleaning operation, laser beam irradiation is not performed, but laser beam irradiation can be used together. When laser beam irradiation is used together, it is necessary in some cases to adjust the output of the laser oscillator 16 in order to reduce the local temperature rise in the pattern section due to the irradiation. Although the cleaning apparatus shown in FIG. 1 is provided with a laser beam unit, an excitation unit, and a lamp heater unit, it is not necessary to provide them together. It just has to be. Further, in the above description, when a laser beam is applied to a concave / convex portion of a substrate having a concave / convex pattern formed on the surface thereof as in the case of manufacturing a semiconductor device, a temperature rise in that portion is suppressed. Although the substrate is cooled for this purpose, the substrate itself does not need to be cooled in order to simply remove a substrate having no uneven portion or dust attached to the back surface of the substrate.

FIG. 2 shows a configuration of a main part of a cleaning apparatus in which dust attached to a flat substrate surface is removed. As shown in the drawing, specifically, in the present example, it is assumed that dust attached to the back surface of the substrate is removed. While the etching gas from the etching gas supply pipe 15 is supplied directly into the processing chamber 1, the processing chamber 1 is exhausted through the exhaust port 4 and the internal pressure is maintained at a set pressure. . The substrate 6 to be processed is also supported by the substrate holder 22 with three claws in the processing chamber 1, and the laser beam 19 from outside the processing chamber 1 passes through the quartz ring window 2, 6. Irradiated to scan the entire back surface.

More specifically, Cl ₂ is supplied into the processing chamber 1 as an etching gas, and the pressure inside the processing chamber 1 is set to 100 Pa. The pressure is not limited to 100Pa, but if the pressure increases,
Since dust floats due to the flow of gas, it is desirable to set the pressure to a low pressure. In this state, the back surface of the substrate 6 is irradiated with the laser beam 19, and at the time of the irradiation, the laser beam 19 is irradiated so as to be parallel to the surface. When the laser beam 19 is irradiated in this manner, the laser beam 19 is totally reflected on the back surface of the substrate 6, so that the temperature rise in the substrate 6 itself is suppressed. However, when dust adheres to the substrate 6, the dust is not reflected by the laser beam and its energy is absorbed by the dust, so that the temperature of the dust reaches a high temperature. . Since the surrounding atmosphere is Cl ₂ , the dust reacts with Cl and vaporizes as chloride. Again, in this case,
If F ₂ , HCL, HF or the like is used as an etching gas, it is possible to cope with the case where dust is SiO ₂ or the like.

As described above, the present invention has been described. In the description, the energy beam is described as a laser beam, but the present invention is not limited to this, and an electron beam or an ion beam can be used in some cases. .

[Effects of the Invention] As described above, in the case of the first to fourth aspects, the dust attached to the substrate can be selectively removed only by the dry process type cleaning. In this case, an apparatus capable of performing such cleaning can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of a configuration of an example of a cleaning device according to the present invention, and FIG. 2 is a diagram showing a cross section of a configuration of another example of a cleaning device according to the present invention. 1 ... processing chamber, 2 ... quartz ring window, 4 ... exhaust port, 5
…… stage, 6 …… substrate, 8a, 8b …… refrigerant piping, 10…
Helium gas supply pipe, 12 excitation chamber, 14 magnetron, 15 etching gas supply pipe, 16 laser oscillator, 17 mirror, 19 laser beam, 20 lamp heater, 22 … Substrate holder

Claims (8)

(57) [Claims] 1. A cleaning method in which dust is reacted with a reactive gas in a vacuum atmosphere and then removed by vaporization, wherein the substrate is placed in an excited reactive gas atmosphere. A cleaning method in which energy is supplied such that dust is vaporized by a selective reaction with a reactive gas so that a temperature rise of dust attached to the substrate is greater than that of the substrate. 2. A cleaning method for removing dust by reacting it with a reactive gas in a vacuum atmosphere and vaporizing the dust, the method comprising the steps of: The supply is performed in a state where the thermal resistance between the stage in the cooled state and the substrate is kept small, so that the temperature rise of the dust attached to the substrate is larger than that of the substrate. A cleaning method in which dust is vaporized by a selective reaction with a reactive gas. 3. A cleaning method in which dust is reacted with a reactive gas in a vacuum atmosphere and then removed by vaporization, wherein a laser beam, an electron beam and an electron beam are applied to a substrate placed in the reactive gas atmosphere. A beam, or an ion beam, is irradiated on the substrate surface at an angle close to parallel to the substrate surface, so that the temperature rise of dust attached to the substrate is larger than that of the substrate, A cleaning method in which dust is vaporized by a selective reaction with a reactive gas. 4. A cleaning method for removing dust by reacting dust with a reactive gas in a vacuum atmosphere, and removing the dust by reacting the dust with a reactive gas in a reactive gas atmosphere. The supply is performed by uniformly irradiating the substrate surface with light or infrared rays from above the substrate surface in a state where the thermal resistance between the stage in the cooled state and the substrate is kept small. Done at
A cleaning method wherein a temperature rise of dust attached to the substrate is made larger than that of the substrate, and the dust is vaporized by a selective reaction with a reactive gas. 5. A cleaning device for reacting dust adhered to a substrate with an excited reactive gas in a vacuum processing chamber and removing the dust by evaporating the dust. A cleaning device having at least a means for placing and setting a substrate on the substrate, a means for supplying energy to the substrate, and a means for setting a temperature rise of dust adhered to the substrate to be greater than that of the substrate. . 6. A cleaning apparatus for reacting dust adhered to a substrate with a reactive gas in a vacuum processing chamber and removing the dust by vaporizing the substrate, wherein the substrate is placed and set in a reactive gas atmosphere. And a means for scanning and irradiating the substrate surface with any one of a laser beam, an electron beam, and an ion beam at an angle nearly parallel to the substrate surface. 7. A cleaning apparatus for reacting dust adhering to a substrate with an excited reactive gas in a vacuum processing chamber and removing the dust by vaporizing the dust. Means for placing and setting the substrate, means for supplying energy to the substrate, and means for placing and setting the substrate, while suppressing the thermal resistance between the means and the substrate in a cooled state. And a cleaning device. 8. A cleaning apparatus for reacting dust adhered to a substrate with an excited reactive gas in a vacuum processing chamber and removing the dust by evaporating the dust. Means for placing and setting a substrate, and light from above the substrate surface with respect to the substrate surface of the substrate,
Alternatively, a cleaning apparatus comprising: means for uniformly irradiating infrared rays; means for cooling the means for placing and setting the substrate; and means for suppressing the thermal resistance between the means and the substrate in a cooled state.