JP2532353B2 - Vapor phase etching 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 vapor phase etching method and apparatus for anisotropic etching.
In particular, the present invention activates or decomposes a reactive gas for etching by cyclotron resonance by microwaves, applies a high frequency or a DC electric field to a substrate to be etched or a member to be etched on the surface of the substrate, The present invention relates to a vapor phase etching method and apparatus for anisotropically etching a member to be etched on the surface.

[0002]

2. Description of the Related Art A plasma etching method (glow discharge etching method) is known as an etching (gas phase chemical removing method) technique by a gas phase etching reaction. In the plasma etching method, a reactive gas for etching is activated or decomposed by a high frequency or a DC electric field. This plasma etching method is adopted in a VLSI manufacturing process as anisotropic etching with high pattern transfer accuracy. However, the degree of improvement of the pattern transfer accuracy (promotion of anisotropy) of the plasma etching method is behind the recent progress of the miniaturization technology of VLSI. Therefore, an anisotropic etching technique with high pattern transfer accuracy is required.

As an anisotropic etching technique, an etching method using electron cyclotron resonance is known. Cyclotron resonance can be generated under the conditions of a frequency of 2.45 [GHz] and a strong magnetic field of 875 [Gauss], for example, when argon is used as a resonance atom. The etching method using cyclotron resonance is
The entire surface of the substrate to be etched or the film (film) to be etched on the substrate can be etched.

[0004]

However, in the etching method using the cyclotron resonance, since the reactive gas moves parallel to the entire surface by the cyclotron resonance, it has a fine width or a fine diameter and a deep depth. The selective anisotropic etching having a large thickness cannot be performed. Specifically, the etching method using cyclotron resonance requires a submicron (1
It is not possible to perform hole-like processing having a width or diameter of [μm] or less, for example, 0.2 [μm]) and a depth of 2 [μm] to 4 [μm].

In addition, the etching method using cyclotron resonance has a cyclotron resonance space for generating a cyclotron resonance in order to spread the excited gas activated or decomposed by the cyclotron resonance over the entire surface of the substrate to be etched or the film to be etched. It is necessary to increase the size of the air-core coil for generating a magnetic field that generates a strong magnetic field, and the etching apparatus becomes large in size. Furthermore, after performing anisotropic etching, it is necessary to remove the resist which is a mask for performing anisotropic etching. The removal of the resist was performed by a chemical method after the substrate or a member to be etched on the surface of the substrate was once discharged from the reaction space. Therefore, it is necessary to remove the resist and process the waste liquid.

The present invention is intended to solve the above problems, and it is an object of the present invention to provide a vapor phase etching method and apparatus which can promote the anisotropy of anisotropic etching and can downsize the apparatus. And

[0007]

[Means for Solving the Problems]

(First invention) In order to achieve the above-mentioned object, the vapor-phase etching method of the present invention comprises heating a substrate or a substrate (10) surface arranged in a reaction space (1) and then heating the substrate or the substrate (10). ) A high frequency or direct current electric field is applied to the member to be etched on the surface in the vertical direction, so that the reaction space (1) is formed in the direction perpendicular to the surface of the member to be etched arranged in the reaction space (1). A cyclotron resonance space is provided by projecting so as to be connected and supplying microwaves to an air-core coil for magnetic field generation wound around a cyclotron resonance space (2) having a smaller cross-sectional area than the reaction space (1). Cyclotron resonance is generated in (2), and the reactive gas for etching is decomposed and activated in the reaction space (1) by the high frequency or the DC electric field, and at the same time, the cyclone resonance is generated. In combination with energy degradation and activated non-product gas by Ron resonance and performing selective anisotropic etching on the etched member.

(Second Invention) The vapor phase etching apparatus of the present invention comprises an exhaust system for exhausting unnecessary gas while adjusting the exhaust amount,
A heating means (7) for heating a reaction space (1) to which a doping system for introducing a product gas and a non-product gas is connected, and a substrate or a substrate (10) surface arranged in the reaction space (1). ), (7 '), a high frequency or DC power source (6) for applying a high frequency or DC electric field in the vertical direction to the substrate or a member to be etched on the surface of the substrate (10), and the reaction space (1). ), Which is perpendicular to the surface of the member to be etched and is projected so as to be connected to the reaction space (1), and has a cross-sectional area smaller than that of the reaction space (1). 2) and an air-core coil for generating a magnetic field wound around the cyclotron resonance space (2) to generate a cyclotron resonance by supplying a microwave into the cyclotron resonance space (2). ), (5 ') and in the reaction space (1), the reactive gas for etching is decomposed and activated by the high frequency or DC electric field, and the non-product gas decomposed and activated by cyclotron resonance is A vapor-phase etching apparatus characterized in that anisotropic etching is selectively performed on a member to be etched by using energy together.

[0009]

[Operation] Based on the steps described above, the present invention has the following effects. First, after heating the substrate or the substrate surface provided in the reaction space, a high frequency or DC electric field is applied to the member to be etched formed thereon.
The cyclotron resonance space is projected in a direction perpendicular to the surface of the member to be etched so as to be connected to the reaction space, and has a smaller cross-sectional area than the reaction space. Then, the reactive gas for etching performs anisotropic etching by using the energy of the non-product gas decomposed and activated by cyclotron resonance in the reaction space and the energy obtained by the high frequency or DC electric field. Selective. The vapor-phase etching method of the present invention can perform anisotropic etching having a submicron width or diameter on a substrate or a member to be etched on the substrate.

In the present invention, the reactive gas for etching may be, for example, CF ₄ , CF ₂ H ₂ , CFH ₃ , CF.
₃ H, CCl ₄ , nitrogen fluoride (NF ₃ , N ₂ F ₆ ), hydrogen fluoride (HF), fluorine (F ₂ ), hydrogen chloride (HCl) or chlorine (Cl ₂ ), or either A carrier gas or a mixed gas of oxygen is used. In the present invention, since the reactive gas for etching whose activation, decomposition or reaction is promoted by the cyclotron resonance is accelerated by the electric field applied between the pair of electrodes and is given directionality, anisotropic etching is performed. Anisotropy can be further promoted. In the present invention, the direction in which the electric field is applied is set perpendicular to the surface of the substrate to be etched or the material to be etched on the substrate. As a result, the present invention can realize hole-like processing having a width or diameter on the submicron level and a depth of several [μm]. The present invention uses argon, which is a typical inert gas, as the non-product gas (a gas that itself produces only a gas even when decomposed or reacted). In the present invention, any of helium, neon and krypton may be used as the non-product gas.

As described above, according to the present invention, the reactive gas for etching is activated or decomposed by glow discharge in the reaction space, or anisotropic etching is performed by the reaction to activate or decompose the reactive gas for etching. Alternatively, since the cyclotron resonance is also used to accelerate the reaction, both the resonance space for generating the cyclotron resonance and the air-core coil for magnetic field generation can be downsized, and the entire gas phase etching apparatus can be downsized. Further, in the present invention, in the above anisotropic etching, the anisotropy can be further promoted by heating the substrate to be etched or the material to be etched on the substrate in a temperature range from room temperature to 300 [° C.].

[0012]

EXAMPLE An example of the present invention will be described below. FIG. 1 is a configuration diagram showing an outline of a cyclotron resonance type plasma etching apparatus which is an embodiment of the present invention. In FIG. 1, the reaction space (1) is composed of a stainless reaction container (1 ′) and a lid (1 ″). A substrate holder (10 ') is provided on the reaction container (1'). The substrate holder (10 ') is mounted with a substrate to be etched or a substrate (10) having a material to be etched (for example, a film to be etched) on its surface. The substrate to be etched or the substrate (10) is mounted by opening the lid (1 ″) provided on the upper side of the reaction container (1 ′) so as to be opened and closed upward.

A halogen lamp heater (7) is provided inside the lid (1 ''). The halogen lamp heater (7) irradiates infrared rays to the back surface of the substrate (10) to be etched through a quartz window (19) arranged between the substrate (10) and the reaction space (1). Can be heated. In this embodiment, the reaction vessel (1 ′) is heated from room temperature to 300 [° C.] by the halogen lamp heater (7).
The substrate to be etched (10) can be heated within the temperature range of.

In the reaction space (1), on the back surface of the substrate (10) to be etched mounted on the substrate holder (10 ') facing the surface to be etched, or on the back surface of the substrate (10) on which the material to be etched is not formed. One reticulated electrode (20 ') is arranged in the position portion. Further, in the lower part of the reaction space (1) of the reaction container (1 ′), the other one reticulated electrode (20) is arranged at a position facing and separated from the one reticulated electrode (20 ′). Set up. Each of the mesh electrodes (20 '), (20) is connected to a high frequency power source or a direct current power source (6). And between each of the mesh electrodes (20 '), (20), 13.
A high frequency or direct current electric field of 56 [MHz] is applied.

In the present embodiment, the surface to be etched of the substrate to be etched (10) mounted on the substrate holder (10 ') or the surface of the material to be etched of the substrate (10) is perpendicular to the direction of the applied electric field. Is set to. The reaction space (1) of the reaction vessel (1 ') is connected to the doping system (13') through the gas supply system (16). The doping system (13 ') supplies a reactive gas for etching into the reaction space (1). The reactive gas for etching is supplied to a plurality of ring-shaped nozzles (1) arranged in the reaction space (1).
It is uniformly discharged into this reaction space (1) through 7). As the reactive gas for etching, CF ₄ , C
F ₂ H ₂ , CFH ₃ , CF ₃ H, CCl ₄ , nitrogen fluoride (NF ₃ , N ₂ F ₆ ), hydrogen fluoride (HF), fluorine (F ₂ ), hydrogen chloride (HCl) or chlorine (Cl) ₂ )
Or a gas in which oxygen is mixed with either carrier gas or oxygen is used.

The reaction space (1) of the reaction vessel (1 ') is located below the reaction vessel (1'), that is, on the side of the other mesh electrode (20), and the mesh electrode (2).
One end of the cyclotron resonance space (2) is connected in a direction (on an extension line) that coincides with the direction of the electric field applied between 0 ') and (20). The cyclotron resonance space (2) is composed of a quartz tube (resonance vessel: 29). And a resonance container (29) consisting of a quartz tube
Is formed in an elongated shape protruding downward from the lower surface of the reaction vessel (1 ′) in a substantially vertical direction. A doping system (13) is connected to the cyclotron resonance space (2) through a gas supply system (18). The doping system (13) supplies a non-product gas to the cyclotron resonance space (2). Argon, helium, neon, or krypton is used as the non-product gas.
In this example, argon is used as the non-product gas.

Around the outer periphery of the resonance container (29), air-core coils (5) and (5 ') for magnetic field generation are arranged from one end side to the other end side of the cyclotron resonance space (2). This air-core coil (5) and (5 ') for magnetic field generation
Applies a magnetic field to the non-product gas supplied into the cyclotron resonance space (2). The other end of the cyclotron resonance space (2) is connected to a microwave oscillator (3) through an analyzer (4). The microwave oscillator (3) oscillates a microwave of, for example, 2.45 [GHz] into the cyclotron resonance space (2) and causes the non-product gas supplied into the cyclotron resonance space (2) to perform cyclotron resonance. generate.

The reaction space (1) in the reaction vessel (1 ') is connected to a vacuum exhaust system (11) composed of control valves (14), (15) and a vacuum pump (9) which also uses a turbo pump. To be done. The evacuation system (11) has a pressure in the reaction space (1) and the cyclotron resonance space (2) connected to the reaction space (1) in a range from a normal pressure state to a reduced pressure state, that is, 1 [torr] to 10 ⁻⁴ [to].
rr], for example, 0.03 [torr] to 0.001 [tor]
r] can be adjusted. When the pressures of the reaction space (1) and the cyclotron resonance space (2) connected to the reaction space (1) are maintained at a reduced pressure, the reactive gas for etching can be sufficiently spread in the reaction space (1) and the cyclotron resonance can be achieved. Cyclotron resonance can be easily generated in the space (2).

In the cyclotron resonance type plasma etching apparatus having such a structure, first, argon gas as a non-product gas is supplied into the cyclotron resonance space (2), and the argon gas for magnetic field generation is supplied to the argon gas (5). ) And (5 ′) from the magnetic field determined by the mass and frequency of argon (eg 875 [Gauss]),
Each of the microwaves is given from the microwave oscillator (3). The argon gas is excited and pinched by the magnetic field, and at the same time, cyclotron resonance occurs in the cyclotron resonance space (2). After being fully excited, this electronized and excited argon gas is released into the reaction space (1). At the exit of the cyclotron resonance space (2) from which this argon gas is released, the reactive gas for etching supplied from the doping system (13 ') through the gas supply system (16) and the plurality of ring-shaped nozzles (17). It is mixed with (22). By this mixing, the reactive energy for etching (22) is given the excitation energy of the non-product gas (21), and the activation, decomposition or reaction of the reactive gas for etching (22) is promoted.

Further, in the reaction space (1), the reactive gas for etching (22) whose activation, decomposition or reaction has been promoted is applied between the pair of mesh electrodes (20) and (20 '). The applied electric field accelerates and gives directionality. As a result of the combined use of cyclotron resonance with this plasma glow discharge, the reactive gas for etching (22) whose activation, decomposition or reaction has been promoted in the reaction space (1) has a direction that matches the direction of the applied electric field. Then, the surface of the substrate to be etched (10) or the surface of the material to be etched of the substrate (10) is selectively anisotropically etched. Moreover, the anisotropy of this anisotropic etching is promoted. Further, the cyclotron resonance type plasma etching apparatus applies cyclotron resonance to the non-product gas (21) to such an extent that the reactive gas for etching (22) supplied into the reaction space (1) is activated, decomposed or reacted. Since it is sufficient if it is generated, the cyclotron resonance space (2) and the magnetic field generating air-core coils (5) and (5 ′) can be downsized, and the entire apparatus can be downsized.

<Experimental example> In this experimental example, the silicon semiconductor substrate was etched with NF ₃ using the cyclotron resonance type plasma etching apparatus of the above-mentioned embodiment.
This is an experimental example. The cyclotron resonance type plasma etching apparatus controls the pressure in the reaction space (1) to 0.003 [tor].
r], NF ₃ was supplied as a reactive gas for etching (22) into the reaction space (1) from the doping system (13 ′) at 20 [cc / min], and a self-bias was applied 13. A high frequency electric field of 56 [MHz] is applied.

On the other hand, in the cyclotron resonance space (2), argon gas is supplied as a non-product gas (21) from the doping system (13) at 50 [cc / min]. The microwave has a frequency of 2.45 [GHz] and an output in the range of 30 [W] to 500 [W],
For example, the output is adjusted to 200 [W]. Further, the resonance strength of the air-core coils (5) and (5 ') for generating a magnetic field is 8
It is set to 75 [Gauss]. Substrate to be etched (1
For 0), a silicon semiconductor substrate, specifically, a non-single crystal semiconductor substrate, for example, an amorphous silicon (amorphous) semiconductor substrate is used. A photoresist film as an etching mask is selectively coated on the surface to be etched of the substrate to be etched (10). Under the above-mentioned conditions, etching was actually started, the amorphous silicon semiconductor substrate was selectively removed, and unnecessary gas was released from the reaction space (1) by the vacuum exhaust system (11).

As a result, the etching rate is 15 [Å /
Sec] was obtained. This etching rate is three times as fast as 5 [Å / sec] obtained only by plasma etching. Further, if a pattern is cut in the photoresist film with a width of 0.3 [μm] on the surface of the amorphous silicon semiconductor substrate, a hole-like processing with a width of 0.3 [μm] and a depth of 4 [μm] is obtained. It was realized. That is, the anisotropy of anisotropic etching could be reliably promoted. Furthermore, the cyclotron resonance type plasma etching apparatus removes the reactive gas (22) for etching in the reaction space (1) after the anisotropic etching is completed. Then, an ashing gas such as oxygen is introduced into the reaction space (1). That is, the organic resist + O ₂ → nCO ₂ ↑ + nH ₂ 0 ↑ is obtained, and the photoresist film on the surface of the substrate (10) can be removed by ashing.

As described above, the removal of the photoresist film on the surface of the substrate (10) can be continuously performed without exposing the substrate (10) to the outside of the reaction space (1). Further, it is not necessary to treat waste liquid after removing the photoresist film. As described above, according to one embodiment of the present invention, in a vapor phase etching apparatus, anisotropy of anisotropic etching can be promoted and the apparatus can be downsized. Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment. And
Various design changes can be made without departing from the present invention described in the claims.

For example, according to the present invention, a photoelectric conversion element, a light emitting element, a MISFET (field effect semiconductor element), an SL element (super lattice element), a semiconductor device having a HEMT element, or an etching adopted in a VLSI manufacturing process. Applicable to technology. Similarly, the present invention can be applied to an etching technique adopted in a manufacturing process of a semiconductor laser device or an optical integrated circuit device. Further, in the present invention, in the above-mentioned etching technique using cyclotron resonance, a photo-etching technique for simultaneously applying light energy may be used together. In this case, the present invention, in particular, uses an excimer laser (wavelength 10
0 nm to 400 nm), an argon laser, a nitrogen laser or the like can be used to freely or appropriately select the resonance wavelength.

Further, in the present invention, any one of a single crystal silicon semiconductor substrate (film), a polycrystalline silicon semiconductor substrate (film), a glass substrate and a stainless steel substrate may be used as the substrate to be etched. Similarly, the present invention provides a 3-5 group compound semiconductor substrate such as Ga as the substrate to be etched.
As substrate, GaAlAs substrate, InP substrate, GaN substrate, or aluminum or silicide metal may be used. Further, the present invention is not limited to the single crystal semiconductor substrate as the substrate to be etched, but may be a non-single crystal semiconductor substrate such as SiGe _1-x (0 <X <1), SiO _{2 -x} (0 <X
<2), SixC _1-x (0 <X <1), Si ₃ N
_An amorphous semiconductor substrate containing Si such as _4-x (0 <X <4) may be used. In addition, the present invention may have a structure in which the substrate to be etched is mounted on the lower side or vertically in FIG. 1, and the cyclotron resonance and the electric field may be emitted from the upper direction to the lower direction or to the lateral direction.

[0027]

As described above, according to the present invention,
Since it is a cyclotron resonance space that has a cross-sectional area smaller than that of the reaction space and is projected so as to be connected to the reaction space in a direction perpendicular to the surface of the member to be etched arranged in the reaction space, vapor phase etching is performed. Even if the device is downsized, uniform anisotropic etching can be performed with high accuracy evenly over the entire surface of the substrate.
According to the present invention, the reactive gas for etching and the activated inert gas and / or non-product gas are evenly supplied from the vertical direction to the substrate having a large area to perform anisotropic etching. , Submicron width and diameter or depth can be easily processed.

According to the present invention, the reactive gas for etching is decomposed and activated by the energy of the high frequency and the DC electric field, and the energy of the non-product gas decomposed and activated by the cyclotron resonance is used together, Since the surface of the member to be etched is anisotropically etched, the submicron width and diameter or the depth can be easily processed. According to the present invention, during anisotropic etching, by heating the substrate to be etched or the material to be etched on the substrate, the anisotropy can be further promoted, and the substrate or the member to be etched on the substrate can have a submicron width or Anisotropic etching having a diameter can be performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of a cyclotron resonance type plasma etching apparatus which is an embodiment of the present invention.

[Explanation of symbols]

 1 ... Reaction space 1 '... Reaction vessel 2 ... Cyclotron resonance space 3 ... Microwave oscillator 4 ... Analyzer 5, 5' ... Air-core coil for magnetic field generation 6 ... High frequency or DC power supply 7, 7 '... Halogen lamp heater 9 ... Vacuum pump 10 ... Substrate or substrate to be etched 11 ... Vacuum exhaust system 13, 13' ... Doping system 17 ... Nozzle 20, 20 '... Reticulated electrode 21 ... Inert gas and / or non-product gas 22 ... Reactive gas for etching 29 ... Resonance container

Claims (2)

(57) [Claims] 1. A substrate or a substrate surface arranged in the reaction space is heated, and then a high frequency or DC electric field is applied in a vertical direction to the substrate or a member to be etched on the substrate surface to dispose the substrate or the substrate surface in the reaction space. For generating a magnetic field that is perpendicular to the surface of the member to be etched and is projected so as to connect to the reaction space and is wound around the cyclotron resonance space having a smaller cross-sectional area than the reaction space. Microwaves are supplied to the air-core coil to generate cyclotron resonance in the cyclotron resonance space, and in the reaction space, the reactive gas for etching is decomposed and activated by the high frequency or DC electric field, and decomposed by cyclotron resonance. Anisotropic etching is selectively performed on the member to be etched using the energy of the activated non-product gas. A vapor-phase etching method, which comprises performing etching. 2. An exhaust system for exhausting an unnecessary gas while adjusting an exhaust amount, a reaction space to which a doping system for introducing a product gas and a non-product gas is connected, and a reaction space arranged in the reaction space. Heating means for heating the substrate or the substrate surface; a high frequency or direct current power source for applying a high frequency or direct current electric field in the vertical direction to the substrate or the member to be etched on the substrate surface; A cyclotron resonance space that is perpendicular to the surface of the member to be etched and that is connected to the reaction space and has a smaller cross-sectional area than the reaction space, and a microwave is supplied to the cyclotron resonance space. In order to generate cyclotron resonance, an air-core coil for generating a magnetic field wound around the cyclotron resonance space, and in the reaction space, The reactive gas for etching is decomposed and activated by a high frequency or DC electric field, and the energy of the non-product gas decomposed and activated by cyclotron resonance is also used to selectively anisotropically etch the member to be etched. A vapor-phase etching apparatus characterized by performing.