JP3795867B2 - Etching apparatus, etching method, and manufacturing method of semiconductor device - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a semiconductor manufacturing apparatus, and more particularly to a wet etching apparatus, a wet etching method, and a semiconductor device manufacturing method.
[0002]
[Prior art]
In recent years, high dielectric constant films have been used as gate insulating films for advanced devices. The high dielectric constant film is changed to a physical property that is difficult to be etched because the densification of the film is promoted by heat treatment (annealing) performed after the film formation.
Conventionally, an etching process for a film to be etched is performed by wet etching in which the film to be etched is brought into contact with a chemical solution and etched by an etchant dissociated in the chemical solution, or radicals and ion species excited in plasma are used as a substrate. Then, dry etching is used in which the film to be etched is forcibly etched.
[0003]
[Problems to be solved by the invention]
However, when a dense thin film such as a high dielectric constant film after annealing is wet etched, there is a problem that the etching rate is extremely low. For this reason, there has been a problem that the throughput is significantly reduced.
In addition, when a dense thin film is dry etched instead of wet etching, an etching rate higher than that of wet etching can be obtained, but there is a problem that a base film that should not be removed is continuously etched. That is, there is a problem that the etching selectivity with respect to the base film cannot be obtained sufficiently by dry etching.
Conventionally, such etching difficulty has been a major obstacle in applying high dielectric constant films to advanced devices.
[0004]
The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide an etching apparatus and an etching method that have a high etching selectivity with respect to a base film to be processed and a high etching rate.
[0005]
[Means for solving the problems]
An etching apparatus according to the present invention is an etching apparatus that wet-etches an HfO ₂ film or an HfAlO film that is a film to be processed on a substrate,
A chemical supply section for supplying a chemical onto the film to be processed;
Has the chemical and opposing optical transmission window layer of surfactant is provided on the surface, the ultraviolet light irradiation unit for irradiating before Symbol film to be processed with ultraviolet light through the light transmitting window through the chemical And
By irradiating the ultraviolet light having an energy higher than the binding energy of the molecules forming the film to be processed from the ultraviolet light irradiation part, the bonds of the molecules of the film to be processed are cut, and the cut molecules are It is characterized by etching with a chemical solution .
[0007]
In the etching apparatus according to the present invention, it is preferable that the ultraviolet light irradiation unit is disposed at a position 2 mm to 5 mm away from the film to be processed.
[0008]
In the etching apparatus according to the present invention, the ultraviolet light irradiation unit is
A light source that emits the ultraviolet light;
Houses a light source, and a housing portion having a transparent window in the film to be processed and the opposing surfaces,
The chemical solution supply unit is provided on a side of a gap between the light transmission window and the film to be processed , and includes a nozzle having a tip portion inserted into the gap .
It is preferable that the nozzle continuously supplies the chemical liquid to the gap while the ultraviolet light is emitted from the light source .
[0010]
In the etching apparatus according to the present invention, the chemical solution supply unit includes a switching valve connected to the nozzle,
A pipe connected to the switching valve for supplying the chemical solution;
Connected to said switching valve, it is preferable that further comprising a pipe for supplying washing liquid.
[0011]
A method of manufacturing a semiconductor device according to the present invention includes a step of wet etching a HfO ₂ film or an HfAlO film that is a film to be processed using the etching apparatus,
The step of wet etching the film to be processed includes:
A first sub-step of supplying a chemical on the film to be processed;
Ultraviolet light through the light transmission window and a second sub-step of morphism irradiation to the film to be processed through the chemical solution,
In the second sub-step, by irradiating ultraviolet light having energy higher than the binding energy of the molecules forming the processed film, the molecular bonds of the processed film are cut, and the cut molecules are It is characterized by etching with a chemical solution .
[0012]
An etching method according to the present invention is a method of wet etching a HfO ₂ film or a HfAlO film which is a film to be processed on a substrate,
Supplying a chemical onto the film to be processed;
And a step of morphism irradiation with ultraviolet light through a light transmissive window having a layer of surfactant on the chemical and surface opposed to the film to be processed through the chemical solution,
Molecule in the step of irradiating the ultraviolet light, the cut the binding molecules of the film to be processed by irradiating ultraviolet rays having a higher energy than the binding energy of the molecules forming the film to be processed, which is the cutting Is etched with the chemical solution .
[0013]
In the etching method according to the present invention, it is preferable to simultaneously perform the step of supplying the chemical solution and the step of irradiating the ultraviolet light .
[0014]
In the etching method according to the present invention, the chemical solution is always supplied from one end of the substrate and the chemical solution is discharged from the other end of the substrate while the ultraviolet light is irradiated on the film to be processed. Thus, it is preferable to continue supplying the chemical solution .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof may be simplified or omitted.
[0016]
Embodiment 1 FIG.
FIG. 1 is a schematic cross-sectional view for explaining an etching apparatus according to Embodiment 1 of the present invention. In detail, it is a figure for demonstrating the etching apparatus which wet-etches the to-be-etched film formed on the board | substrate.
[0017]
As shown in FIG. 1, a substrate 11 on which an etching target film (film to be processed) that is a dense thin film is formed is rotatably held on a rotary stage 5. Specifically, a plurality of pins 4 are provided on the rotary stage 5, and the end portion (side edge portion) of the substrate 11 is fixed by being sandwiched between these pins 4. The substrate 11 may be held by an electrostatic chuck.
[0018]
A rotation shaft 6 is provided at the center of the rotation stage 5, and the substrate 11 also rotates at a desired rotation speed by rotating the rotation stage 5 about the rotation shaft 6. For example, the rotating stage 5 rotates at a rotational speed of about 300 to 500 rpm at the time of chemical application, and rotates at a rotational speed of about 2000 to 3000 rpm at the time of drying.
[0019]
Further, the film to be etched is, for example, a high dielectric constant film such as an HfO ₂ film or an HfAlO film which is formed by using an ALD (Atomic Layer Deposition) method and then subjected to an annealing process (PDA: Post Deposition Annealing). (High-k film).
[0020]
A chemical 9 is supplied from the nozzle 8 provided at the tip of the chemical pipe 7 to the surface of the film to be etched on the substrate 11. The chemical solution pipe 7 is connected to a chemical solution tank that stores the chemical solution via a valve or a pump or to a chemical solution supply line of ancillary equipment (not shown).
Moreover, the chemical | medical solution 9 can use what contains a phosphoric acid base etchant, for example. In order to obtain desired characteristics, a surfactant or the like may be added to the chemical solution 9.
[0021]
Above the substrate 11, a lamp house 2 that houses a lamp that is a light source 1 that irradiates an etching target film with ultraviolet light via a chemical solution 9 is disposed. As the lamp 1, for example, KrCl (wavelength 222 nm), Xe ₂ (172 nm), Kr ₂ (147 nm), Ar ₂ (126 nm) excimer lamp or the like can be used. Here, the lamp 1 irradiates ultraviolet light with an energy higher than the binding energy of the molecules forming the film to be etched. The energy of ultraviolet light can be controlled by the irradiation time of ultraviolet light, and the irradiation time is, for example, 10 sec to 200 sec.
Further, the material of the chemical 9 and the thickness on the film to be etched are controlled so as to have a high transmittance with respect to the wavelength of the ultraviolet light emitted from the lamp 1.
[0022]
An opening having a size equal to or larger than that of the substrate 11 is formed on the lower surface of the lamp house 2. This opening is covered with a light transmission window 3 formed of a material that transmits ultraviolet light emitted from the lamp 1. The light transmission window 3 is, for example, a window made of quartz glass (hereinafter referred to as “quartz glass window”).
The interior of the lamp house 2 sealed by the quartz glass window 3 is filled with an inert gas such as nitrogen. Thereby, the lamp | ramp 1 which has the wavelength absorbed in oxygen presence can be used. The illuminance of ultraviolet light in the quartz glass window 3 is preferably about 5 to ²⁰ mW / cm ² , for example.
[0023]
On the upper surface of the lamp house 2, a drive unit 10 for driving the lamp house 2 in the vertical direction is provided. By driving the driving unit 10, the lamp house 2 is disposed in the vicinity of the substrate 11 when irradiating the ultraviolet light, and the ultraviolet light from the lamp 1 can be applied to the etching target film at a close distance. Specifically, the lamp house 2 is disposed so that the quartz glass window 3 is located above the surface of the substrate 11 by about 2 mm to 5 mm.
[0024]
Next, the operation of the etching apparatus, that is, wet etching of the film to be etched will be described.
First, the substrate 11 on which the HfO ₂ film is formed as an etching target film is fixed on the rotary stage 5 by the pins 4. And the chemical | medical solution 9 containing a phosphoric acid base etchant is supplied on the board | substrate 11 from the nozzle 8, rotating the board | substrate 11 by the rotational speed of 300-500 rpm by rotating the rotary stage 5 centering on the rotating shaft 6. FIG. . Thereafter, when the chemical solution 9 is sufficiently thin and uniformly spread on the substrate 11, the rotation is stopped. At this time, the chemical solution 9 is applied to the entire substrate 11 with a desired thickness without flowing away from the substrate 11.
[0025]
Then, the lamp house 2 is moved down by the drive unit 10 so that the quartz glass window 3 does not interfere with the pin 4 and is separated from the surface of the substrate 11 by about 2 mm to 5 mm. The HfO ₂ film is irradiated with ultraviolet light through the chemical solution 9. At this time, the light energy of the ultraviolet light breaks the Hf-O bond of the HfO ₂ film, and the etching reaction proceeds by the etchant contained in the chemical solution 9 applied in advance.
[0026]
After completion of the desired etching, the ultraviolet light irradiation by the lamp 1 is stopped, the lamp house 2 is raised by the drive unit 10, and ultrapure water is separately discharged onto the substrate 11 from the water washing nozzle, and the chemical solution 9 remaining on the substrate 11 is left. Rinse away.
Thereafter, the substrate 11 is rotated at about 2000 to 3000 rpm by the rotating stage 5 to shake off the ultrapure water on the substrate 11 and perform drying.
[0027]
As described above, in the first embodiment, after supplying the chemical solution 9 onto the dense film to be etched, the ultraviolet light having light energy exceeding the binding energy of the molecules forming the film to be etched is applied to the chemical liquid 9. Then, the film to be etched was irradiated. By irradiation with this ultraviolet light, the bonds of the molecules forming the film to be etched are broken, and the etching rate of the film to be etched that comes into contact with the chemical 9 is greatly increased. That is, by performing wet etching with the molecular bond of the film to be etched most severed, the etching rate can be greatly increased. Therefore, the etching processing time can be shortened and the throughput can be improved. Further, since it has a high etching selectivity with respect to the base film, the problem of continuously etching the base film as in the case of using dry etching does not occur. Thereby, a dense high dielectric constant film can be applied to the advanced device.
[0028]
Further, the chemical 9 used in the first embodiment has a high transmittance with respect to the wavelength of the lamp 1. For this reason, the ultraviolet light emitted from the lamp 1 is hardly absorbed by the chemical solution 9, and the ultraviolet light can reach the film to be etched with sufficient light energy. Therefore, it is possible to reduce the loss of ultraviolet light energy due to the chemical 9 as much as possible.
[0029]
Further, the etching rate can be further improved by raising the temperature of the chemical solution 9 and the substrate 11 using a heat exchanger, a hot plate, or the like. However, in this case, the evaporation amount of the chemical 9 increases, and the surface of the quartz glass window 3 below the lamp house 2 may be clouded by condensation. This fogging causes the ultraviolet light to be scattered, and the action of the ultraviolet light on the film to be etched may be insufficient.
As a countermeasure against this, it is preferable to apply a surfactant having a hydrophobic group to the quartz glass window 3. With this surfactant film, condensation on the quartz glass window 3 can be prevented and loss of light energy of ultraviolet light can be prevented (the same applies to Embodiment 2 described later).
[0030]
In addition, it may be considered that if the chemical solution 9 is supplied only once, the amount of the etchant in the chemical solution 9 consumed during the etching is insufficient, and the etching reaction stops midway. In this way, when the rate of supply of the etchant is limited, the lamp unit 2 is once separated (raised) from the vicinity of the substrate 11 by the driving unit 10, and the chemical solution 9 is supplied again from the nozzle 8, and then the lamp house 2 is mounted on the substrate. It is good to lower to 11 vicinity and to perform ultraviolet light irradiation again.
[0031]
However, in the etching mechanism, when the rate of supplying the etchant is extremely limited, it is necessary to repeat the supply of the chemical solution and the irradiation with ultraviolet light many times, so that the process time becomes long and the throughput is reduced. Moreover, the chemical | medical solution 9 may dry with the heat | fever which the light energy of the ultraviolet light irradiated after chemical | medical solution application | coating gives, and may change to an irreversible state at the time of the water washing after an etching. In such a case, an effective means will be described as a second embodiment described later.
[0032]
In the first embodiment, the case where the film to be etched is a high dielectric constant film has been described. However, the present invention is not limited to this, and the present invention can be applied to a film having a low wet etching rate. It is suitable for a thin film (the same applies to Embodiment 2 described later).
[0033]
In addition, as a comparative example of the first embodiment, the present inventor applied the chemical solution 9 on the etching target film after first irradiating the etching target film with ultraviolet light from the lamp 1. However, in this comparative example, the increase in the etching rate was slight compared with the first embodiment, and the desired effect was not obtained.
[0034]
Embodiment 2. FIG.
2 is a schematic cross-sectional view for explaining an etching apparatus according to Embodiment 2 of the present invention, and FIG. 3 is a top view showing the vicinity of the substrate in the etching apparatus shown in FIG.
The etching apparatus according to the second embodiment is particularly suitable when the rate of supplying the etchant is extremely limited as described above.
[0035]
As shown in FIG. 2, the substrate 11 on which the film to be etched is formed is held on a plate-like stage 12 having a larger area than the substrate 11. A plurality of pins 4 having a height of 2 to 5 mm, for example, are provided on the stage 12, and the end portion of the substrate 11 is fixed by being sandwiched between these pins 4.
[0036]
As in the first embodiment, the lamp house 2 in which the lamp 1 is housed is moved up and down by the drive unit 10. When irradiating with ultraviolet light, the lamp house 2 is arranged so that the quartz glass window 3 is located above the surface of the substrate 11 by about 2 mm to 5 mm.
[0037]
In the gap between the quartz glass window 3 and the substrate 11, the tip of a slit-like flat nozzle 13 disposed on the side of the gap is inserted, and the chemical solution 9 is continuously supplied from the flat nozzle 13 to the gap. . Here, as shown in FIG. 3, a pair of guides 16 is formed on the stage 12 so as to be orthogonal to the flat nozzle 13 and sandwich the substrate 11. As a result, the chemical 9 supplied from the flat nozzle 13 to one end of the substrate 11 is guided by the guide 16 in the direction of the other end facing the one end (that is, the direction opposite to the flat nozzle 13), and gradually passes through the gap. Satisfy. Further, the excessive amount of the chemical solution 9 supplied from the flat nozzle 13 flows out from the opposite direction of the flat nozzle 13.
[0038]
The flat nozzle 13 is connected to one end of the pipe 15. The other end of the pipe 15 is connected to the chemical liquid pipe 15 a and the ultrapure water pipe 15 b through the switching valve 14. That is, by the switching operation of the switching valve 14, the flat nozzle 13 and the pipe 15 are connected to the chemical liquid pipe 15a or the ultrapure water pipe 15b.
[0039]
Next, the operation of the etching apparatus, that is, wet etching of the film to be etched will be described.
First, the substrate 11 on which an HfO ₂ film is formed as an etching target film is fixed on the stage 12.
Then, the lamp house 2 is lowered by the driving unit 10 so that the quartz glass window 3 does not interfere with the pin 4 and is located at a position 2 mm to 5 mm away from the surface of the substrate 11.
[0040]
Next, the tip portion of the flat nozzle 13 is inserted into the gap between the quartz glass window 3 and the substrate 11 from the side, and the chemical 9 is continuously supplied from the flat nozzle 13 to the gap. Simultaneously with the supply of the chemical solution 9, the ultraviolet light is irradiated from the lamp 1 through the chemical solution 9 to the HfO ₂ film.
At this time, the light energy of the ultraviolet light breaks the Hf—O bond of the HfO ₂ film, and the etching reaction proceeds by the etchant contained in the chemical 9 supplied from the flat nozzle 13. The chemical 9 supplied from the flat nozzle 13 is guided to the opposite side of the flat nozzle 13 by the guide 16 and gradually fills the gap, and then fills the gap. Further, by continuing to supply the chemical liquid 9 at a constant flow rate, the excessive chemical liquid 9 flows out of the substrate 11 on the opposite side of the flat nozzle 13. Thereby, the etchant-rich chemical solution 9 is supplied onto the etching target film.
[0041]
After completion of the desired etching, the ultraviolet light irradiation by the lamp 1 is stopped. Then, with the position of the lamp house 2 as it is, the switching valve 14 is switched, and ultrapure water is supplied from the flat nozzle 13 to the gap to wash away the chemical 9 remaining on the substrate 11. At this time, not only the chemical solution 9 remaining on the substrate 11 is washed away, but also the portion in contact with the chemical solution 9 such as the quartz glass window 3 is simultaneously cleaned.
[0042]
As described above, in the second embodiment, wet etching is performed by simultaneously supplying the chemical liquid 9 by the flat nozzle 13 and irradiating the lamp 1 with ultraviolet light. Therefore, the same effect as in the first embodiment can be obtained.
Further, in the second embodiment, the chemical solution 9 is continuously applied by the flat nozzle 13 in the gap between the quartz glass window 3 and the substrate 11 during wet etching, that is, while the lamp 1 is irradiated with ultraviolet light. To supply. As a result, the etchant-rich chemical 9 can always be supplied onto the film to be etched. Therefore, the etching rate can be further increased as compared with the first embodiment. Therefore, it is not necessary to repeat the chemical supply and the ultraviolet light irradiation even in the above-described etchant supply-limited etching reaction, and it is possible to prevent the process time from increasing and the throughput from decreasing. Moreover, it can prevent that the chemical | medical solution 9 dries and changes to an irreversible state at the time of water washing.
In the second embodiment, ultrapure water is supplied from the flat nozzle 13 by the switching operation of the switching valve 14. Thereby, not only the substrate 11 but also the wetted parts such as the flat nozzle 13 and the quartz glass window 3 can be cleaned. Therefore, it is not necessary to provide a separate nozzle for ultrapure water, and the etching apparatus can be simplified and the cost can be reduced.
[0043]
【The invention's effect】
According to the present invention, it is possible to provide an etching apparatus and an etching method that have a high etching selectivity with respect to a base film to be processed and a high etching rate.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view for explaining an etching apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic sectional view for explaining an etching apparatus according to a second embodiment of the present invention.
3 is a top view showing the vicinity of a substrate in the etching apparatus shown in FIG. 2. FIG.
[Explanation of symbols]
1 Light source (lamp)
2 Lamphouse 3 Light transmission window (quartz glass window)
4 Pin 5 Rotating stage 6 Rotating shaft 7 Chemical liquid pipe 8 Nozzle 9 Chemical liquid 10 Drive unit 11 Substrate 12 Stage 13 Flat nozzle 14 Switching valve 15 Pipe 15a Chemical liquid pipe 15b Ultrapure water pipe 16 Guide

Claims (8)

An etching apparatus for wet etching a HfO ₂ film or an HfAlO film that is a film to be processed on a substrate,
A chemical supply section for supplying a chemical onto the film to be processed;
Has the chemical and opposing optical transmission window layer of surfactant is provided on the surface, the ultraviolet light irradiation unit for irradiating before Symbol film to be processed with ultraviolet light through the light transmitting window through the chemical And
By irradiating the ultraviolet light having an energy higher than the binding energy of the molecules forming the film to be processed from the ultraviolet light irradiation part, the bonds of the molecules of the film to be processed are cut, and the cut molecules are An etching apparatus characterized by etching with a chemical solution . The etching apparatus according to claim 1,
The said ultraviolet light irradiation part is arrange | positioned in the position 2 mm-5 mm away from the said to-be-processed film | membrane, The etching apparatus characterized by the above-mentioned. The etching apparatus according to claim 1 or 2,
The ultraviolet light irradiation part is
A light source that emits the ultraviolet light;
Containing the light source, and having a light-transmitting window on a surface facing the film to be processed,
The chemical solution supply unit is provided on a side of a gap between the light transmission window and the film to be processed, and includes a nozzle having a tip portion inserted into the gap.
The etching apparatus is characterized in that the nozzle continuously supplies a chemical solution to the gap while the ultraviolet light is emitted from the light source . In the etching apparatus according to 請 Motomeko 3,
The chemical liquid supply unit includes a switching valve connected to the nozzle,
A pipe connected to the switching valve for supplying the chemical solution;
An etching apparatus further comprising: a pipe connected to the switching valve for supplying a cleaning liquid. The HfO ₂ film or HfAlO film is film to be processed using the etching apparatus according to any one of claims 1 to 4 A method of manufacturing a semiconductor device comprising the step of wet etching,
The step of wet etching the film to be processed includes:
A first sub-step of supplying a chemical on the film to be processed;
Ultraviolet light through the light transmission window and a second sub-step of morphism irradiation to the film to be processed through the chemical solution,
In the second sub-step, by irradiating ultraviolet light having energy higher than the binding energy of the molecules forming the processed film, the molecular bonds of the processed film are cut, and the cut molecules are Etching with a chemical solution . A method for manufacturing a semiconductor device . The HfO ₂ film or HfAlO film is film to be processed on the base plate there is provided a method of wet etching,
Supplying a chemical onto the film to be processed;
And a step of morphism irradiation of ultraviolet light through the light transmission window layer of surfactant on the chemical and facing surfaces provided on the film to be processed through the chemical solution,
Molecule in the step of irradiating the ultraviolet light, the cut the binding molecules of the film to be processed by irradiating ultraviolet rays having a higher energy than the binding energy of the molecules forming the film to be processed, which is the cutting Is etched using the chemical solution . The etching method according to claim 6 , wherein
An etching method comprising simultaneously performing the step of supplying the chemical solution and the step of irradiating the ultraviolet light . In the etching method according to 請 Motomeko 6,
While the ultraviolet light is irradiated on the film to be processed, the chemical liquid is always supplied from one end of the substrate, and the chemical liquid is continuously discharged from the other end of the substrate. An etching method characterized by the above.

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