JP2002016033A - Apparatus and method of substrate dry cleaning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve efficiency in cleaning for the inside of a microscopic holes formed on a substrate, with respect to a substrate dry cleaning apparatus using an excimer lamp. SOLUTION: Ultraviolet-rays irradiated from an excimer lamp unit 30 are reflected by a reflector 32 into a beam, almost in parallel with the axis of minute-diameter hole formed on the substrate 14 and are irradiated on the substrate 14 mounted in a treatment chamber 12. As a result, the irradiation of the ultraviolet rays can surely reach the depth of minute-diameter hole, so the ultraviolet rays are irradiated to the substrate 14 and the inside of the microscopic diameter hole of the substrate 14. By using the cleaning gas fed to the treatment chamber 12 and the ultraviolet rays, the residue (organic matter on the surface and inside the microscopic diameter hole of the substrate 14 can be removed reactively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a substrate dry cleaning apparatus and a substrate dry cleaning method for dry cleaning a substrate by ultraviolet light emitted from an excimer lamp.

[0002]

2. Description of the Related Art In recent years, dry cleaning using an excimer lamp has been used as a method for cleaning a semiconductor wafer (hereinafter, collectively referred to as a substrate). When a rare gas such as xenon is put into an excited state, a rare gas atom or a rare gas molecule in the excited state becomes
Combined with a rare gas atom or a rare gas molecule in the ground state, a dimer called excimer is formed. This excimer has the property of generating ultraviolet light when returning to the ground state. An excimer lamp is a lamp utilizing this property, in which a high voltage is applied between electrodes to generate discharge plasma, thereby exciting a sealed rare gas and irradiating ultraviolet light. The ultraviolet light has a function of decomposing molecular bonds of organic substances, and by irradiating the substrate, contaminated organic substances adhered to the substrate are decomposed, and as a result, the substrate can be dry-cleaned without using a cleaning liquid. Ultraviolet light emitted from an excimer lamp using xenon gas has higher photon energy and higher decomposition ability of organic substances than ultraviolet light from a conventional mercury lamp. Ultraviolet light emitted from an excimer lamp also has a function of decomposing bonds of oxygen molecules and generating excited oxygen atoms. By supplying oxygen at the time of cleaning the substrate, the decomposed organic matter is oxidized by the excited oxygen atoms, and a volatile gas (hereinafter, referred to as a volatile gas) is generated and easily removed.

FIG. 4 is a diagram showing a chemical reaction occurring in dry cleaning using an excimer lamp. Hereinafter, the principle of dry cleaning using an excimer lamp in which xenon gas is sealed will be described with reference to FIG.

The excimer of xenon gas has a wavelength of 172 nm.
When ultraviolet light is emitted to irradiate oxygen supplied for reacting the ultraviolet light with an organic substance, excited oxygen atoms are generated. The reaction formula is as shown in (1) of FIG.

The ultraviolet light is oxygen O₂Is absorbed by
Zon O₃And ozone O ₃More excited oxygen atoms
Are generated, and the oxidizing power increases. The reaction formula is shown in FIG.
As shown in FIG.

Further, when ultraviolet light is applied to an organic substance adhered on a substrate, molecular bonds of the organic substance are decomposed. The decomposed organic matter combines with the excited oxygen atoms generated in the above (1) and (2) and oxidizes to become a volatile gas such as CO, CO ₂ , and H ₂ O. The reaction formula is as shown in (3) of FIG.

That is, when irradiating the substrate with ultraviolet light to decompose the attached organic matter, for example, oxygen is supplied as a purifying gas to generate excited oxygen atoms, which combine with the decomposed organic matter to form volatile oxygen. A certain gas is evolved, making removal easier. It is known that a similar effect can be obtained even when a mixed gas of oxygen and nitrogen is used as the purification gas.

[0008] By the way, the cleaning of a substrate manufactured in a semiconductor manufacturing process is performed not only by removing oil and dust adhering to the surface of the substrate but also by electrically removing fine holes formed in the substrate, for example, front and back surfaces of the substrate. There is a cleaning removal of a substance present in the contact hole for connection.

Usually, as shown in FIG. 5, a substrate 100 manufactured in a semiconductor manufacturing process is made of a base material 10 such as silicon.
2, a lower wiring pattern 104 such as Al or AlCu is formed, and an interlayer insulating film 106 such as a silicon oxide film is formed thereon.
To form Further, a resist is applied on the interlayer insulating film 106, and after performing desired development, dry etching is performed to form a fine hole (contact hole) 108 having a desired diameter. These fine holes 108 are filled with a contact metal material such as tungsten and connected to the upper wiring pattern. As a result, the front and back of the interlayer insulating film 106 are electrically connected. Hereinafter, similarly, the interlayer insulating films are laminated, and a laminated structure is sequentially formed.

In such a semiconductor manufacturing process, the fine holes formed in the substrate have a hole shape having a bottom, in which residues of the resist and those which have been altered are residues (organic substances). It remains as 110. If the residue 110 is present, the contact resistance between the contact metal material filled in the fine hole and the lower wiring pattern 104 increases, thereby lowering the performance of the semiconductor wafer. Therefore, at the time of cleaning, it is required that the fine holes be cleaned similarly to the substrate surface. When performing this cleaning, the substrate 100 to be cleaned is inserted into the processing chamber, and a cleaning gas is supplied into the processing chamber. When the substrate 100 is irradiated with ultraviolet light from an excimer lamp in this state, organic substances attached to the substrate are decomposed. Since the decomposed organic matter is oxidized by the excited oxygen atoms to generate a volatile gas, the substrate is dry-cleaned by removing the volatile gas from the processing chamber.

[0011]

However, the diameter of the fine hole is, for example, about 0.18 μm, and even if the above-described dry cleaning using the excimer lamp is performed, the ultraviolet light of the excimer lamp which is diffused light is used. Is, as shown in FIG.
Since the light is obliquely incident on the fine hole 108, there is a problem that it does not efficiently reach the inside of the fine hole 108. As a result, the residue (organic matter) is not sufficiently decomposed in the fine pores 108, and the cleaning efficiency is reduced, leading to a reduction in substrate quality. This problem becomes more conspicuous as the diameter of the fine pores decreases and as the depth increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a substrate dry cleaning apparatus and a substrate dry cleaning method capable of improving the cleaning efficiency of the inside of a fine hole formed in a substrate. The purpose is to provide.

[0013]

In order to achieve the above object, a dry cleaning apparatus for a substrate according to the present invention comprises: a processing chamber for accommodating a substrate having fine holes therein for dry cleaning; An excimer lamp unit that irradiates the inside of the processing chamber with ultraviolet light that can be incident substantially parallel to the hole axis of the hole, and a gas supply device that supplies a purification gas to the inside of the processing chamber is provided. .

According to another aspect of the present invention, there is provided a method for dry cleaning a substrate having fine holes, comprising:
The substrate is dry-cleaned by irradiating the substrate with ultraviolet light of an excimer lamp substantially parallel to the hole axis of the fine hole.

The term "substrate having fine holes" as used herein generally refers to a semiconductor wafer in the course of a semiconductor manufacturing process and after completion of the manufacturing process. And those that have been processed. Further, the micro-diameter hole is, for example, a hole for making electrical contact between the lower layer surface and the upper layer surface of the substrate, and means, for example, a hole having an extremely fine diameter of 0.18 μm.

According to this structure, since the ultraviolet light emitted from the excimer lamp unit is substantially parallel to the hole axis of the fine hole formed in the substrate, it is possible to surely make the ultraviolet light reach deep inside the fine hole. Can be. As a result, it is possible to reliably and favorably clean the fine pores.

In order to achieve the above-mentioned object, in the above-mentioned substrate dry cleaning apparatus, the excimer lamp unit comprises:
It is characterized by including a reflector which reflects ultraviolet light emitted from the excimer lamp and makes it substantially parallel to the hole axis.

In order to achieve the above object, in the above-mentioned method for dry cleaning a substrate, ultraviolet light of an excimer lamp substantially parallel to the hole axis is formed by a reflector and irradiated on the substrate.

Here, the reflector may be fixed in advance so as to form ultraviolet light substantially parallel to the hole axis, or may be appropriately adjustable.

According to this configuration, the ultraviolet light emitted from the excimer lamp can be easily converted to ultraviolet light substantially parallel to the hole axis.

In order to achieve the above object, in the above-mentioned substrate dry cleaning apparatus, the processing chamber changes a substrate position in a plane orthogonal to substantially parallel ultraviolet light irradiated while the substrate is mounted. It is characterized by including a position change table.

In order to attain the above object, in the above-mentioned substrate dry cleaning method, the irradiation of the ultraviolet light of the excimer lamp substantially parallel to the hole axis may include the step of irradiating the substrate having the fine holes with the substantially parallel ultraviolet light. This is performed while changing the position in a plane orthogonal to the above.

Here, the position change table for changing the substrate position includes rotation and translation in a plane.

According to this configuration, it is possible to efficiently irradiate the entire substrate including the inside of the fine hole with ultraviolet light substantially uniformly.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings. FIG. 1 shows a configuration concept of a substrate dry cleaning apparatus 10 of the present embodiment. The processing chamber 12 includes a substrate loading port 16 for loading a substrate 14 to be cleaned into the inside,
It has a purified gas supply pipe 18 for supplying a purified gas into the processing chamber 12 and an exhaust pipe 20 for discharging volatile gas generated in the dry cleaning. A stage 22 on which the substrate 14 is placed is provided inside the processing chamber 12. The stage 22 is rotated via a transmission belt 26 by driving a motor 24 as a driving device provided outside the processing chamber 12. The method of rotating the stage 22 is arbitrary, and the motor 24 may be directly driven. The stage 22 rotates the substrate 14 horizontally in the processing chamber 12 (rotates in a plane orthogonal to the ultraviolet light substantially parallel to a hole axis of a fine hole formed in the substrate 14 described later). Note that it is desirable that the processing chamber 12 can maintain the airtightness in order to perform cleaning efficiently.

The lamp house 2 is placed on the processing chamber 12.
The lamp house 28 includes a plurality of excimer lamps (excimer lamp units) 30. Ultraviolet light (wavelength: 172 nm) emitted from the excimer lamp 30 passes through the quartz glass 12a and is applied to the substrate 14 inside the processing chamber 12.

The feature of the present embodiment is that the substrate 14 mounted on the stage 22 of the processing chamber 12 is
Dry cleaning is performed by irradiating ultraviolet light substantially parallel to the hole axis of the fine hole formed in the substrate 14.

In the embodiment shown in FIG. 1, a reflector 32 is arranged on the back of the excimer lamp 30 (at a position facing the substrate 14), and the ultraviolet light 30a diffusely radiated from the excimer lamp 30 is reflected to become parallel light 30b. ing. In this embodiment, the reflector 32 is arranged for each excimer lamp 30. Further, it is desirable that the lamp house 28 has a structure in which all the ultraviolet light from the excimer lamp 30 can be irradiated into the processing chamber.

FIGS. 2A to 2D are enlarged views of the substrate 14 having the fine holes 34, and also show the manufacturing process. The manufacturing process of the substrate 14 is the same as the conventional one. As shown in FIG. 2A, a lower wiring pattern 14b of Al or AlCu is formed on a base material 14a of silicon or the like, and a silicon oxide film is formed thereon. An interlayer insulating film 14c such as a film is formed. Furthermore, after applying a resist on the interlayer insulating film 14c and performing desired development (development according to the shape of the fine holes 34 and the like), dry etching using a gas such as fluoride or chloride is performed. Thereby, a fine hole (contact hole) 34 having a desired diameter is formed.

In this state, the fine hole 34 has a bottomed shape due to the lower wiring pattern 14b. And
The residue of the resist and the degenerated residue thereof remain as residue (organic material) 36 inside the fine diameter hole 34. As described above, the residue 36 causes deterioration of the quality of the semiconductor wafer. In the present embodiment, the residue 3
6 with ultraviolet light 30 b substantially parallel to the hole axis 38 of the fine diameter hole 34.
To remove by washing.

By making the ultraviolet light 30b substantially parallel to the hole axis 38 of the minute diameter hole 34, the ultraviolet light 30b can reach the inside of the minute diameter hole 34 (particularly, the bottom portion and the side wall portion of the minute diameter hole 34).
It is possible to make sure that light is incident,
A shadow portion that the ultraviolet light 30b does not reach is not formed inside, and the reaction shown in FIG. 4 can be reliably performed, and the inside of the fine hole 34 can be completely cleaned. In particular, since the ultraviolet light 30b substantially parallel to the hole axis 38 can easily enter the inside of the fine-diameter hole 34, highly reliable cleaning can be performed regardless of the diameter of the fine-diameter hole 34. Becomes possible. Cleaning of the surface of the substrate 14 and the like is performed at the same time by the ultraviolet light 30b substantially parallel to the hole axis 38.

The fine holes 34 of the cleaned substrate 14 are filled with a contact metal material 14d such as tungsten as shown in FIG. 2 (b), and as shown in FIG. The pattern 14e is formed. as a result,
The front and back of the interlayer insulating film 14c are electrically connected. Less than,
The interlayer insulating film 14f is laminated, and if necessary, fine holes are formed in the interlayer insulating film 14c as described above, followed by cleaning, and the semiconductor manufacturing process is continued.

As shown in FIG. 1, the stage 22 on which the substrate 14 is mounted is
By rotating in a plane perpendicular to the ultraviolet light 30b substantially parallel to the hole axis 38 of the above, ultraviolet light can be uniformly and rapidly incident on the inside of a plurality of irregularly-sized fine holes 34 on the substrate 14. Therefore, efficient dry cleaning can be performed. Also, as the stage 22 rotates,
The purified gas supplied to the processing chamber 12 is agitated, and the purified gas is evenly distributed in the processing chamber 12, so that an effect of promoting the cleaning reaction can be expected.

By the way, the applicant of the present invention has an excimer lamp 3
In the case of dry cleaning using 0, it has been confirmed that the cleaning reaction can be further promoted by humidifying the purification gas supplied into the processing chamber 12.

FIG. 3 shows a humidifier 40 for humidifying the purified gas in this embodiment. In the present embodiment, a mixed gas of oxygen supplied from the supply port 42 and nitrogen supplied from the supply port 44 is used as the purified gas supplied to the purified gas supply pipe 18. The humidifier 40 is provided in the nitrogen gas pipe 46. Humidifier 4 in the present embodiment
Numeral 0 includes a bubbling container 40a, and a substantially constant amount of water is always stored and supplied from the supply port 48 to the bubbling container 40a. The nitrogen gas supply pipe 46 opens into the water in the bubbling vessel 40a via the flow rate controller 40b. Accordingly, in the bubbling container 40a, the moisture of the saturated nitrogen vapor pressure is humidified into the dry nitrogen gas and sent to the purified gas supply pipe 18. In an embodiment,
The nitrogen gas is sent to the purified gas supply pipe as dry nitrogen gas via the flow controller 40c, but by appropriately restricting both the flow controllers 40b and 40c, the dry nitrogen gas and the humidified nitrogen gas are removed. Can be arbitrarily controlled. Of course, in the purification gas supply pipe 18, the humidified nitrogen gas is mixed with the oxygen gas and supplied to the processing chamber 12.

In this embodiment, although not shown, a humidity detector is provided in the processing chamber 12, and the humidity in the processing chamber is constantly monitored. The detected humidity value is supplied to a humidity control device (not shown) to control the purified gas humidity of the humidifier 40 to a desired value.

In this embodiment, the cleaning gas atmosphere in which the cleaning process is performed is preferably controlled at a relative humidity of 0 to 60%, and more preferably at a relative humidity of 10 to 40%.

The dry cleaning apparatus 10 configured as described above
Will be described.

When the dry cleaning is started, the substrate dry cleaning apparatus 10 loads one substrate 14 to be subjected to dry cleaning into the processing chamber 12 through the substrate transfer port 16 and places it on the stage 22. Thereafter, the processing chamber 12 is closed, and the humidified purified gas is supplied from the purified gas supply pipe 18 into the processing chamber 12. It is desirable that the substrate dry cleaning apparatus 10 be capable of adjusting the concentration and amount of the supplied humidification purification gas and the humidification. Subsequently, ultraviolet light 30b substantially parallel to the hole axis 38 of the fine diameter hole 34 of the substrate 14 is applied to the substrate 14 from the excimer lamp 30 and the reflector 32 of the lamp house 28 for a predetermined time (for example, 60
Seconds). Substrate dry cleaning apparatus 10 uses ultraviolet light 30b
During the irradiation, the stage 24 on which the substrate 14 is mounted is rotated via the transmission belt 26 by driving the motor 24.

The ultraviolet light 30 substantially parallel to the hole axis 38
When the reflector 32 is used to form the b, only the ultraviolet light 30b that is substantially parallel is the ultraviolet light emitted from the excimer lamp 30 toward the reflector 32,
In a portion directly below the excimer lamp 30, there is a portion where no parallel light is present (the portion immediately below the excimer lamp 30 is substantially parallel to the hole axis 38, but the periphery thereof is not parallel. There is no light).

Then, by rotating the stage 22, the formed substantially parallel ultraviolet light 30 b is transmitted to the fine hole 34.
Can be uniformly applied to the entire substrate 14 including the inside of the substrate. Therefore, if the stage 22 is moved in parallel in an arbitrary direction in addition to the rotation, it is possible to efficiently irradiate the substantially parallel ultraviolet light 30 b to the entire substrate 14. Note that the substrate 14 also receives diffused light emitted from the excimer lamp 30 without passing through the reflector 32,
Cleaning of the surface of the substrate 14 is performed favorably as before. Further, the substrate dry cleaning apparatus 10 may be capable of adjusting the irradiation time of the ultraviolet light or the rotation speed of the stage 22. Further, the supply of the humidification purification gas from the purification gas supply pipe 18 may be continuously performed during the irradiation of the ultraviolet light.

After a lapse of a predetermined time, the substrate dry cleaning apparatus 10
The exhaust gas from the processing chamber 12 is exhausted from the exhaust pipe 20 from the humidifying purifying gas, the residue (organic matter) 36 and the purifying gas generated by the irradiation of the ultraviolet light. After that, it is confirmed that the humidifying purification gas and the volatile gas have been exhausted, and the substrate 14 is unloaded from the processing chamber 12 through the substrate loading port 16. Thus, the dry cleaning for one substrate 14 is completed. Thereafter, dry cleaning of the substrate 14 is sequentially and sequentially performed according to the above-described procedure. Note that, by providing a means for stirring the humidification purification gas, for example, a fan or the like in the processing chamber 12, the reaction efficiency at the time of irradiation with ultraviolet light can be improved.

The configuration of the substrate dry cleaning apparatus 10 shown in the present embodiment is an example, and the substrate having the fine hole 34 is formed in a state where the ultraviolet light radiated from the excimer lamp 30 is substantially parallel to the hole axis 38. The configuration of the substrate dry cleaning apparatus 10 can be appropriately changed as long as it is configured to perform cleaning by irradiating the substrate 14, and the same effect as in the present embodiment can be obtained. Further, in the present embodiment, an example is described in which the reflector 32 is used to make the ultraviolet light emitted from the excimer lamp 30 substantially parallel to the hole axis 38, but if ultraviolet light parallel to the hole axis 38 can be formed, Any means may be used, and even if parallel ultraviolet light is formed by the structure and arrangement of the excimer lamp 30, the same effect as in the present embodiment can be obtained.
Further, in the present embodiment, the example in which the reflector 32 is fixed on the upper part of the excimer lamp 30 has been described. However, the angle may be adjustable according to the shape of the substrate 14 and the state of formation of the fine holes 34.

Further, in this embodiment, an example in which the purifying gas is humidified in order to perform more efficient cleaning has been described. However, even if the humidification is not performed, the cleaning effect on the fine holes 34 by the parallel ultraviolet light can be obtained. Needless to say.

[0045]

As described above, according to the present invention,
Since the ultraviolet light emitted from the excimer lamp unit is substantially parallel to the hole axis of the fine hole formed in the substrate, the ultraviolet light can surely reach the inside of the fine hole. As a result, it is possible to reliably and favorably clean the fine pores.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration concept of a substrate dry cleaning apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a state of cleaning a fine hole and a manufacturing process of a substrate in a substrate dry cleaning apparatus according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating a configuration concept of a humidifier for mixed gas of the substrate dry cleaning apparatus according to the embodiment of the present invention.

FIG. 4 is a diagram showing a chemical reaction formula at the time of dry cleaning by an excimer lamp using xenon gas.

FIG. 5 is an explanatory view illustrating a state of conventional cleaning of a fine hole formed in a substrate.

[Explanation of symbols]

10 substrate dry cleaning device, 12 processing chamber, 14
Substrate, 16 Substrate carry-in port, 18 Purified gas supply pipe, 20 Exhaust pipe, 22 stage, 28 lamp house, 30 excimer lamp, 32 reflector.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masatake Fukuyama 1-10-14 Itabashi, Itabashi-ku, Tokyo Inside the Tokyo Cathode Research Laboratory, Inc. (72) Inventor Maki Kanai 1-110-14 Itabashi, Itabashi-ku, Tokyo No. Within the Tokyo Cathode Research Laboratory (72) Inventor Shunji Yamamoto 1-10-14 Itabashi, Itabashi-ku, Tokyo F-term within the Tokyo Cathode Research Laboratory (Reference) 3B116 AA03 AB01 AB34 BB62 BB88 BC01

Claims (6)

[Claims] 1. A processing chamber for accommodating a substrate having a fine hole therein for dry cleaning, and irradiating the inside of the processing chamber with ultraviolet light which can be incident substantially parallel to a hole axis of the fine hole. A substrate dry cleaning apparatus, comprising: an excimer lamp unit; and a gas supply device for supplying a purification gas into the processing chamber. 2. The cleaning apparatus according to claim 1, wherein the excimer lamp unit includes a reflector that reflects ultraviolet light emitted from the excimer lamp and makes the ultraviolet light substantially parallel to the hole axis. apparatus. 3. The cleaning apparatus according to claim 1, wherein the processing chamber changes a position of the substrate in a plane orthogonal to substantially parallel ultraviolet light irradiated while the substrate is mounted. A substrate dry cleaning apparatus comprising a position changing table. 4. A dry cleaning method for a substrate having fine holes, the method comprising: irradiating the substrate with ultraviolet light of an excimer lamp substantially parallel to a hole axis of the fine holes to dry clean the substrate. Characteristic dry cleaning method for substrates. 5. The method for dry cleaning a substrate according to claim 4, wherein ultraviolet light of an excimer lamp substantially parallel to the hole axis is formed by a reflector and irradiated on the substrate. 6. The cleaning method according to claim 4, wherein the irradiation of the ultraviolet light of the excimer lamp substantially parallel to the hole axis is performed.
A method of dry-cleaning a substrate, wherein the method is performed while changing the position of the substrate having the fine holes in a plane orthogonal to the substantially parallel ultraviolet light.