JPH06291063A - Surface treatment device - Google Patents

Abstract

PURPOSE:To provide a surface treatment device utilizing plasma which can prevent the contamination of a substrate to be treated by sputtering the inner wall of a reaction container with ions inside plasma. CONSTITUTION:The device is provided with a reaction container 1 for introducing plasma source gas, a second DC voltage power supply 26 for controlling the potential of the reaction container 1, a support stage 3 which is provided inside the reaction container 1 and on which a substrate 2 to be treated is mounted, a first DC voltage power source 25 for controlling the potential of the support stage 3, a first vacuum container 6 for generating electrons, and an electrode and coils 15 and 17 for introducing an electron beam into a reaction container 1 for turning the plasma source gas into plasma.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment device,
In particular, it relates to a surface treatment apparatus using plasma.

[0002]

2. Description of the Related Art In recent years, many important elements such as computers and communication devices are connected with a large number of basic elements such as transistors and resistors so as to obtain a desired electric circuit function, and these are integrated and formed on one chip. Integrated circuits (LSIs) are widely used. Therefore, the performance of the entire device is
It is largely linked to the performance of a single unit.

The performance improvement of the LSI itself can be realized by increasing the degree of integration, that is, by miniaturizing the elements. Therefore, there is an increasing demand for higher precision of pattern dimensions, and, for example, in the field of etching, the importance of dry etching, which has higher processing precision than wet etching, is increasing.

As one of the dry etching apparatuses, there is a type (electron beam excitation plasma etching apparatus) of a type in which a reactive gas is excited by an electron beam to generate plasma. In this type of electron beam excitation plasma etching apparatus, as shown in FIG. 25, an electron beam generator 81 generates plasma by, for example, glow discharge, and extracts and accelerates electrons from the plasma to generate an electron beam 82. The electron beam 82 is generated to excite the reactive gas in the reaction container 83 to generate plasma,
This plasma etches the substrate 85 to be processed placed on the support table 84.

However, in this electron beam excited plasma etching apparatus, as shown in FIG. 25, since the substrate 85 to be processed is placed perpendicular to the electron beam 82, the substrate 85 to be processed receives the electron beam 82. When directly received, the substrate 85 to be processed will generate heat. To prevent fever,
Although it suffices to control the temperature of the substrate to be treated 85, it was difficult to control the temperature of the substrate to be treated 85.

Therefore, in order to solve the problem of heat generation, an electron beam excitation plasma etching apparatus of the type in which the substrate 85 to be processed is placed parallel to the electron beam 82 has been proposed as shown in FIG. There is. With such an electron beam excitation plasma etching apparatus, heat generation of the substrate 85 to be processed can be prevented, but there is a problem that uniform etching becomes difficult. This is because the electron density distribution decreases along the traveling direction of the electron beam due to the collision of electrons with the reactive gas, and the plasma density distribution becomes non-uniform.

As the element becomes finer, it is necessary to generate plasma with low energy and low pressure in a film forming method using plasma such as plasma CVD method. Lowering the energy is to reduce the damage to the crystal, and lowering the pressure is to adjust the directionality of the ions. If the directionality of ions is poor, the etching rate differs with respect to the pattern size, and the adverse effect of the microloading effect increases.

For the purpose of low energy and low pressure, plasma sources such as magnetron plasma and ECR plasma are used. However, in the case of this type of plasma source, it is difficult to control the energy of the ions incident on the substrate to be processed. As a method of generating low energy ions in a high vacuum with good controllability, there is an electron beam excitation plasma method (vacuum; Susumu Uramoto, Vol. 20, (5) p. 170). As in the case of the electron beam excitation plasma etching apparatus described above, this is to inject low-speed electrons into the reactive gas in the reaction vessel to ionize the gas phase gas particles.

However, in the surface treatment apparatus utilizing the low-pressure plasma source obtained by this method, the generated ions sputter the inner wall of the reaction vessel of the surface treatment apparatus, and the surface of the substrate to be treated is contaminated. There was a problem. For example, when a reaction vessel made of stainless steel is used, contaminants such as Fe, Ni, Cr and the like attach extremely much to the surface of the substrate to be treated. There is also a problem that it is difficult to independently enter ions, electrons and the like onto the substrate to be processed.

By the way, as a method of forming a thin film in the semiconductor element manufacturing technique, there are a sputtering method, a vapor deposition method, a plasma CVD method, a thermal CVD method, and the like, and any one of the above-mentioned methods can be selected depending on the material and application of the thin film. Is selected. For example, the oxide film used as the gate insulating film is 800 ° C.
It is formed by thermal oxidation of the silicon substrate in the above high temperature atmosphere. The reason for using such a film forming method is that the gate insulating film directly affects the device characteristics, so that it needs to be a good quality film and avoids damaging the base in the film forming process.

The film forming method is selected in consideration of film quality, step coverage, low temperature film forming, and the like. In particular, as the degree of integration of semiconductor elements progresses, it is necessary to form a metal film and an insulating film having fine irregularities on the surface, and it is necessary to consider step coverage. For example, as shown in FIG. 27A, a film is formed on the surface of a substrate 91 to be processed having a groove with a high aspect ratio (1 or more) by a method such as a sputtering method, an evaporation method or a plasma CVD method. 27B, the thin film 92 becomes thicker at the upper part of the groove opening as shown in FIG. For this reason, even if an attempt is made to fill the groove with the thin film 92, when the film thickness of the thin film 92 exceeds a certain value, the upper portion of the opening is blocked with the thin film 92, and a space (void) is formed in the groove. This is because a large amount of deposited particles from the vapor phase adhere to the inlet portion with a large solid angle that allows the vapor phase to form a film.

In a system such as the thermal CVD method in which the film formation process is surface-controlled, the thickness of the thin film 92a is uniform in the groove as shown in FIG. 27 (c). However, when attempting to fill the groove with the thin film 92a, the thin films growing from the left and right toward the center of the groove collide with each other to form a discontinuous boundary, so that the groove cannot be completely filled in this case as well.

As a method of completely filling the groove, a selected CV is used.
There is D method. In this method, for example, as shown in FIG. 28A, first, a SiO ₂ film 93 is formed on a silicon substrate 91, and a desired region of this SiO ₂ film 93 is etched to form a groove. Then, as shown in FIG. 28 (b),
For example, W is selectively deposited on the silicon substrate 91 using WF ₆ / H ₂ , and the trench is filled with the W film 94. However, in the case of this method, the film that can be formed is limited to a metal such as a W film and Al, and the film forming conditions are difficult.
There is a problem that it is extremely difficult to have complete selectivity.

As a film forming method capable of giving directionality to various films such as a metal film and an insulating film, plasma CVD is used.
In the method, there is a method in which a parallel plate type device is used to generate a discharge at a relatively low gas pressure or increase the kinetic energy of ions to align the directionality of incident deposited particles and perform film formation. In this method, as shown in FIG. 28 (c), the film is formed in a directional manner such that the step coverage becomes thicker in the flat portion (bottom portion or upper surface portion) than in the side wall portion of the groove. However, even if it has directionality, it is not perfect, and there is a problem that the film quality deteriorates at the side wall portion where the amount of ion irradiation is small.

[0015]

As described above, in the conventional electron beam excitation plasma etching apparatus, since the plasma density distribution decreases along the traveling direction of the electron beam, the substrate to be processed is uniformly etched. There was a problem that it was difficult to do.

Further, the conventional surface treatment apparatus using the low-pressure plasma source has a problem that the inner wall of the reaction vessel is sputtered by the ions in the plasma and the surface of the substrate to be treated is contaminated.

The present invention has been made in view of the above circumstances, and a first object thereof is to prevent contamination of the surface of a substrate to be processed due to sputtering of the inner wall of the reaction vessel by ions in the plasma. It is to provide a surface treatment apparatus using the obtained plasma.

A second object of the present invention is to provide a surface treatment apparatus utilizing plasma capable of uniformly surface treating a substrate to be treated.

[0019]

In order to achieve the above-mentioned object, the surface treatment apparatus of the present invention (claim 1) has a surface treatment chamber into which a plasma source gas is introduced and a potential of the surface treatment chamber. Means for controlling, a support table provided in the surface treatment chamber for mounting the substrate to be processed, means for controlling the potential of the support table, electron generating means for generating electrons, and accelerating the electrons, A means for guiding the accelerated electrons into the surface treatment chamber and converting the plasma source gas into plasma is provided.

Further, according to another surface treatment apparatus of the present invention (claim 2), a surface treatment chamber into which a plasma source gas is introduced, an electron generating means for generating electrons, and the electrons are accelerated and accelerated. Means for guiding the electrons into the surface treatment chamber to turn the plasma source gas into plasma, and a support provided in the surface treatment chamber and having a support surface formed along the traveling direction of the electrons introduced into the surface treatment chamber. A table, means for controlling the electric potential of the support table, and means for eccentrically arranging and fixing the substrate to be processed on the supporting surface on the electron generating means side are provided.

[0021]

According to the surface treatment apparatus of the present invention (claim 1),
The potential of the surface treatment chamber and the potential of the support can be independently controlled by the means for controlling the potential of the surface treatment chamber and the means for controlling the potential of the support. Therefore, for example, when the ions in the plasma are mainly positive ions, if the potential of the surface treatment chamber is controlled to be positive and the potential of the support table is controlled to be negative, the surface treatment chamber and the positive ions repel each other. Spatter on the inner wall of the surface treatment chamber can be prevented. Therefore, it is possible to prevent the substrate to be treated from being contaminated due to the sputtering of the inner wall of the surface treatment chamber by the ions.

Further, according to the research conducted by the present inventors, when the support base is expanded in the downstream direction of the electron beam, the uniformity of the plasma distribution density on the substrate to be processed becomes higher than in the case where the support base is not expanded. Do you get it. Therefore, according to the surface treatment apparatus of the present invention (Claim 2), since the substrate to be treated is located at the end of the support base on the side opposite to the traveling direction of the electrons introduced into the surface treatment chamber, The uniformity of the plasma distribution density on the substrate to be processed is improved as compared with the case where the substrate to be processed is located at the center of the substrate, and the substrate to be processed can be uniformly surface-treated.

[0023]

Embodiments will be described below with reference to the drawings.

FIG. 1 is a schematic view showing a schematic structure of a surface treatment apparatus according to the first embodiment of the present invention. This surface treatment apparatus is roughly divided into a first vacuum container 6 for generating a discharge and generating plasma, and the first vacuum container 6
The second vacuum container 5 for extracting and accelerating the electrons from the plasma generated in 1., the reactive gas is activated by the irradiation of the electrons accelerated in the second vacuum container 5, plasma is generated, and It comprises a reaction container 1 (surface treatment chamber) for treating the surface of the treatment substrate 2.

The reaction vessel 1 is made of stainless steel, and the reaction vessel 1 is connected to a second DC voltage source 26 (means for controlling the potential of the surface treatment chamber) so that a positive voltage is applied. ing. An exhaust port 4 connected to a vacuum exhaust system is provided in the lower part of the reaction container 1, while the reaction container 1
A gas introduction port 20 for introducing the reactive gas 19 is provided in the upper part of the.

A support base 3 for mounting the substrate 2 to be processed is provided in the reaction vessel. The support base 3 is provided with a temperature adjusting mechanism for heating and cooling the substrate 2 to be processed. Further, the support base 3 is the first DC voltage source 2
5 (unit for controlling the electric potential of the support) and is integrally formed with a mounting member 3a.
Is charged in the rear wall of the reaction vessel 1 and is electrically separated from the reaction vessel 1 by an insulating member 9. That is, the support base 3 can control the potential independently of the reaction container 1.

The reaction vessel 1 is vacuum-connected to the second vacuum vessel 5, and the reaction vessel 1 and the second vacuum vessel 5 are electrically separated by an insulating member 9. An exhaust port 7 connected to a vacuum exhaust system is provided below the second vacuum container 5.

Similarly, the second vacuum container 5 has a first vacuum
The second vacuum container 5 and the first vacuum container 6 are electrically separated from each other by an insulating member 9. The first vacuum container 6 is also provided with an exhaust port 8 connected to a vacuum exhaust system.

The reaction container 1 and the second vacuum container 5 are electrically separated from each other by the insulating member 9 between the reaction container 1 and the second vacuum container 5, and the electron beam passes through the central portion. A cylindrical electrode 10 with holes is provided. The reaction vessel 1 and the second vacuum vessel 5 are vacuum-connected by this hole. The hole has a small conductance and is formed so as to generate a differential pressure. Also, the electrode 1
0 is connected to the third DC voltage source 27, and a positive voltage is applied. Further, in the electrode 10, a coil 15 for generating a magnetic field B ₂ for converging electrons in a region where the electron beam passes is installed insulated from the electrode 10.

Similarly, also between the second vacuum container 5 and the first vacuum container 6, the second vacuum container 5 and the first vacuum container 5 are electrically separated by the insulating member 9 and the central portion is formed. A cylindrical electrode 11 having a hole in its part is provided. This electrode 11
Inside, a coil 16 for generating a magnetic field B ₁ for converging electrons in a region where an electron beam passes is installed insulated from the electrode 11. The electrode 11 is grounded.

The first vacuum container 6 is electrically separated from the first vacuum container 6 by an insulating member 9, and has a gas inlet 13 at the center for introducing a discharge gas 14 such as Ar gas. The provided cylindrical electrode 12 is provided. The electrode 12 is connected to the fourth DC voltage source 28, and a negative voltage is applied.

In the figure, reference numeral 17 denotes a coil for generating a magnetic field B ₃ inside the reaction container 1 so that the electrons passing through the electrode 10 do not spread. Also, the electrode 1
A special material is used for the portion 18 facing the hole through which the 0 and 11 electron beams pass, and the material can be selected depending on the thin film to be formed. Further, in the figure, 21 indicates a thermionic emission material.

Next, a method of forming a thin film using the surface treatment apparatus having the above-mentioned structure will be described.

First, as the discharge gas 14, for example, A
An inert gas such as r is introduced into the first vacuum container 6 through the gas introduction port 13. Next, the pressure in the first vacuum container 6 is reduced to a pressure of several Torr to 10 ^-2 Torr, and a DC voltage is applied between the electrode 11 and the electrode 12 by the fourth DC voltage source 28. Initiate a DC discharge.

Here, in order to stabilize the discharge and obtain a high discharge current, it is preferable to add a thermionic emission material 21 to the electrode 12 as shown in FIG. As the thermoelectron emission material 21, for example, a material such as LaB ₆ is used. The thermoelectron emission material 21 formed of La B ₆ or the like is heated by heat generated by the discharge current flowing through the electrode 12, and emits thermoelectrons. If such a thermionic emission material 21 is used, the discharge current is 6 in a typical DC discharge (the voltage value of the fourth DC voltage source 28 is about 50 V).
A DC discharge of about 7 A can be obtained.

Next, the second vacuum vessel 5 is evacuated while the direct current discharge is generated in the first vacuum vessel 6, and the pressure inside the second vacuum vessel 5 is set in the range of 10 ⁻⁴ Torr. And the DC voltage is applied between the electrode 10 and the electrode 11 by the third DC voltage source 27 to generate an electric field. The electrons are drawn into the first vacuum container 5.

The extracted electrons become an electron beam and have acceleration energy determined by the voltage values of the third DC voltage source 27 or the third DC voltage source 27 and the fourth DC voltage source 28, and the reaction container 1 Be introduced inside. At this time, the coil 15 and the electrode 11 installed in the electrode 10
Electrons are efficiently extracted by the coil 16 installed inside.

The electrons introduced into the reaction vessel 1 excite the reactive gas 19 introduced into the reaction vessel 1, and as a result, a high-density ionized state is formed in the reaction vessel 1.
In this case, the efficiency of ionization (ionization) of the gas depends on the reaction container 1
It depends on the magnitude of the kinetic energy of the electrons (incident electrons) introduced into the interior.

FIG. 2 is a characteristic diagram showing the relationship between the kinetic energy of incident electrons (electron energy) and the generation efficiency of positive ions in the gas phase. It can be seen from FIG. 2 that the generation efficiency of positive ions becomes maximum when the electron energy is about 150 eV, and beyond that, the generation efficiency rapidly deteriorates. Therefore, for efficient ionization,
Considering the distribution of kinetic energy of electrons in the electron beam,
The electron energy needs to be suppressed to about 300 eV or less.

The positive ions in the reaction vessel 1 repel the reaction vessel 1 because a positive voltage is applied to the reaction vessel 1 by the second DC voltage source 26. Therefore, it is possible to prevent the substrate 2 to be treated from being contaminated due to the sputtering of the inner wall of the reaction container 1 due to the positive ions.

Next, with respect to the method for forming an amorphous silicon film using the surface treatment apparatus configured as described above,
This will be described with reference to process sectional views of FIG.

First, as shown in FIG. 3A, a silicon substrate 31 having a groove with a width of about 1 μm formed on the surface thereof is prepared, and the silicon substrate 31 is used as a substrate to be treated to form a support base 3.
Place on. The potential of the reaction vessel 1 is controlled to be the same as that of the electrode 10, and a voltage of −50 V is applied to the support base 3 by the first DC voltage source 25.

Next, as a reactive gas 19, a silicon compound gas, for example, SiH ₄ gas is introduced into the reaction vessel 1 and an electron beam having an electron energy of about 100 to 150 eV is introduced into the reaction vessel 1. An amorphous silicon film is formed on the silicon substrate 31.
The film forming speed can be controlled by the first DC voltage source 25. That is, the higher the voltage in the positive direction, the lower the film formation rate,
The film formation rate becomes almost zero at 00 V or higher.

When the film is formed with the gas pressure of 2 × 10 ⁻³ Torr, the amorphous silicon film 32 is formed by anisotropic deposition of amorphous silicon as shown in FIG. 3B. However, the direction is not perfect.

However, when the film formation is performed with the gas pressure of 2 × 10 ^-4 Torr, the amorphous silicon film 32a is formed by the complete directional deposition of amorphous silicon as shown in FIG. 3 (c). It The amorphous silicon film 32a having such a deposition shape has a gas pressure of 1 ×.
It was confirmed that it can be realized in the case of 10 ⁻³ Torr or less.

In order to form a SiO ₂ film by the above surface treatment apparatus, as the reactive gas 19, a gas containing a silicon compound and oxygen, such as SiH ₄ gas and O ₂ gas.
A mixed gas with a gas is used, and the mixed gas is introduced into the reaction vessel 1 under the condition that the SiH ₄ / O ₂ flow rate ratio is 1 or more, and an electron beam is emitted into the reaction vessel 1 as in the case of the amorphous silicon film. It should be introduced.

Here, it was confirmed that when the film formation was carried out at a gas pressure of 1 × 10 ⁻³ Torr or less, complete directional film formation could be performed as in the case of the amorphous silicon film. Further, by heating the temperature of the substrate to be treated to about 300 ° C., a high quality SiO ₂ film could be obtained. Specifically, when the film was evaluated by a dielectric breakdown test, it was confirmed that a SiO ₂ film having a withstand voltage of 8 MV / cm or more was obtained.

In addition, Si _x N _{y can be obtained} by the surface treatment apparatus.
To form a film, a gas containing a silicon compound and nitrogen, for example, a mixed gas of SiH ₄ gas and N ₂ gas is used as a reactive gas, and an electron beam may be introduced into the reaction vessel 1. Here, the composition ratios x and y are SiH ₄ and N
_It can be controlled by changing the flow rate ratio with ₂ . Also in this case, as in the case of the SiO ₂ film, a good quality Si _x N _y film could be formed by raising the temperature of the substrate to be processed.

As described above, the reaction vessel 1 of the surface treatment apparatus of this embodiment is made of stainless steel. Therefore, when the voltage value of the second DC voltage source 26 is made smaller than that of the first DC voltage source 25 during film formation and a negative voltage is applied to the reaction container 1, the reaction container 1 is sputtered by positive ions. The substance generated by this is taken into the film and contaminated.

For example, the voltage value of the first DC voltage source 25 is fixed at 0V, and the voltage value of the second DC voltage source 26 is -50.
When three kinds of amorphous silicon films are formed with V, 0 V, and +50 V, F in the amorphous silicon film
e content is 5 × 10 ¹⁵ / cm ² (−50 V), 3 ×
10 ¹³ / cm ² (0 V), 2 × 10 ¹⁰ / cm ² (+50
V).

As shown in FIG. 4, the current due to the ions incident on the support 3 (support current) and the current due to the ions incident on the wall of the reaction vessel 1 (reaction wall current) are the support 3 and the reaction vessel 1. Potential difference between (potential of the support 3 −reaction vessel 1
Potential). From this, it is clear that in order to eliminate contamination from the wall of the reaction container 1, it is necessary to apply a higher potential in the positive direction than the support 3 to the reaction container 1.

In order to prevent contamination, the metal portion of the support base 3 other than the region on which the substrate 2 to be processed is placed is coated or covered with an insulating film so that the metal portion is not directly exposed to plasma. Or, when forming the same material as the film to be formed, for example, a silicon film,
It is preferable to use the support base 3 made of silicon.

It is also effective to prevent contamination that at least the region of the electrodes 10, 11 through which the electron beam passes is made of the same material as the film to be formed.

With these measures, the contamination in the film due to the material constituting the device can be suppressed to 10 ¹² / cm ² or less.

FIG. 5 is a diagram showing how H ₂ influences when forming a W film by using the surface treatment apparatus of FIG. 1. Specifically, it is used as a reactive gas. W
It is a view showing the relationship between the specific resistance of the deposition rate and the W film H ₂ amount and the W film to be added to F _6.

The flow rate and pressure of WF ₆ are fixed at 10 sccm and 2 × 10 ^-4 Torr, respectively. The acceleration energy of electrons introduced into the reaction vessel 1 is 100 eV, the voltage value of the first DC power supply 25 is −60 V, and the voltage value of the second DC power supply 26 is 5 V.

It can be seen from FIG. 5 that the W deposition rate first increases with the addition of H ₂ , but when the H ₂ addition amount reaches about 10 sccm, the W deposition rate starts to decrease. On the other hand, the specific resistance is high when the amount of H ₂ added is 20 sccm or less. From these, it can be seen that H ₂ has a function of suppressing incorporation of F into the W film.

FIG. 6 shows that WF ₆ = 10 sccm and H ₂ = 3.
0 sccm, the voltage value of the first DC voltage source 25 is -60
It is a figure which shows the result of having evaluated the step coverage on the level | step difference which has a circular hole of aspect ratio 1 when V and the voltage value of the 2nd DC voltage source 26 are set to 5V, and pressure is changed.

Specifically, as shown in FIG. 7, as a substrate to be processed, SiO ₂ having a groove on a silicon substrate 31 is used.
Using the film with the film 33 formed, the film thickness a at the groove upper part, the film thickness b at the groove side wall part and the film thickness c at the groove bottom of the W film 34 formed under the above conditions are obtained, and the film thickness ratio c /
The step coverage was evaluated by determining the relationship between a, b / c and pressure.

From FIG. 6, below 10 ⁻³ Torr, the film thickness ratio c / a becomes much larger than the film thickness ratio b / c, that is, anisotropic film formation begins to become remarkable, and 10 ^{− Four}
It can be seen that almost complete anisotropic film formation is achieved at less than Torr.

FIG. 8 shows that WF ₆ = 10 sccm and H ₂ = 3.
0 sccm, the voltage value of the second DC voltage source 26 is set to 5 V, the pressure is set to 2 × 10 ⁻⁴ Torr, and the first DC voltage source 2 is set.
5 is a diagram showing how the current I _s flowing through the support base 3 changes when the voltage value V _{s of} 5 is changed, that is, when the voltage applied to the support base 3 is changed.

The current region can be divided into three regions indicated by A, B and C in the figure. In the region A, only positive ions are incident on the support base 3, and only current (ion current) due to positive ions flows through the support base 3. In this region A, as shown in the figure, the film formation is completely anisotropic.

In the region C, only electrons are incident on the support base 3, and only current (electron current) due to electrons flows through the support base 3. In this region C, the film formation is isotropic as shown in FIG.

In the area B, both electrons and positive ions are made incident on the supporting table 3, the ratio of which changes depending on the voltage applied to the supporting table 3, and the current value I _s changes with the voltage value V _s. Is. In this region B, a film is also formed on the side wall of the step, as shown in FIG.

As described above, according to the surface treatment apparatus of this embodiment, the deposition shape can be easily controlled by changing the voltage applied to the support 3. Although the WF ₆ gas is used as the reactive gas for forming the W film in the above description, another W compound, for example, W (CO) ₆ gas may be used.

Further, by using Al compound gas, Cu compound gas or the like as the reactive gas, a metal film other than the W film can be formed. For example, Al (C
An Al film can be formed by using H ₃ ) ₃ or a mixed gas of Al (C ₂ H ₅ ) ₃ and H ₂ . If an acetylacetone type Cu complex is used as the Cu compound gas, C
A u film can be formed.

Further, in order to reduce the C content in the film in forming these metal films, H ₂ may be added to the above reactive gas. Specifically, A using Al (CH ₃ ) ₃
In the case of forming a 1-film or a Cu film using an acetylacetone-type Cu complex gas, by adding H ₂ ,
The C concentration in the film can be reduced by two orders of magnitude.

Alternatively, before introducing the reactive gas into the reaction vessel 1, the reactive gas may be excited in advance by heat, light, discharge or charged beam before being introduced into the reaction vessel 1. The concentration of C content in the film can be remarkably reduced. For example, when Al (CH ₃ ) ₃ is used, by heating Al (CH ₃ ) ₃ at about 200 ° C., the C concentration in the Al film can be reduced by one digit.

Metal vapor may be used as a method for introducing the reactive gas containing metal. That is, Al, Cu
If the metal has a relatively low melting point, such as, a metal vapor can be obtained by heating and evaporating the metal in the reaction vessel 1,
It is not necessary to introduce the metal gas into the reaction container 1 through the gas introduction port 19. Further, in the case of a metal having a high melting point, the vapor can be obtained by sputtering.

Next, a surface oxidation method using the surface treatment apparatus of FIG. 1 will be described.

First, as shown in FIG. 9A, a silicon substrate 41 on which a silicon nitride film 42 is patterned is prepared as a substrate to be processed.

Next, the temperature of the silicon substrate 41 is set to 800 ° C. or higher by the temperature adjusting mechanism of the supporting base 3, preferably 800 to
When heated to about 850 ° C. and surface-treated by introducing O ₂ gas as the reactive gas 19 into the reaction vessel 1,
Directional oxidation is performed, and an oxide film 43 having a shape as shown in FIG. 9B is formed.

Further, as shown in FIG. 9C, if a groove is previously formed on the surface of the silicon substrate 41 in a region not covered with the silicon nitride film 42, as shown in FIG. 9D. Thus, it is possible to form a flat oxide film 43a with no swelling. In addition, it was confirmed that the surface treatment apparatus of this example can generate ions of several tens eV even at a pressure of the order of 10 ⁻⁴ to 10 ⁻⁵ Torr.

When O ₂ gas is used as the reactive gas as in this embodiment, many negative ions such as O ⁻ ions and O ₂ ⁻ ions are also generated. Oxidation by these negative ions is faster than oxidation by O ⁺ ions. In addition, O ^-
In order to generate a large amount of negative ions such as ions and O ₂ ⁻ ions, it is advisable to introduce O ₂ gas into the reaction vessel 1 after previously exciting it with discharge or the like.

Further, the oxide film 4 having a film thickness of 100 nm or more
When only positive ions or only negative ions are supplied when forming 3, 43a, the oxide films 43, 43a are charged up, and the film formation rate is reduced or the directionality is lost.
The film quality may deteriorate. In order to eliminate such inconvenience, it is effective to apply an AC voltage to the support base 3 and cause positive ions and negative ions (or electrons) to alternately enter the surface of the substrate to be processed.

FIG. 10 is a schematic view showing the structure of the main part of a surface treatment apparatus according to the second embodiment of the present invention. In the following drawings of the surface treatment apparatus, parts corresponding to those of the surface treatment apparatus of FIG. 1 are denoted by the same reference numerals as those of FIG. 1, and detailed description thereof will be omitted.

The surface treatment apparatus of this embodiment is different from that of the previous embodiment in that the support base 3 is fixed to the lower portion of the reaction vessel 1. With such a configuration, the support base 3
Since the space in the traveling direction of the electron beam 23 can be effectively used as compared with the case where is fixed to the rear wall of the reaction container 1, it is possible to process more substrates 2 to be processed at once.

FIG. 11 is a schematic diagram showing the structure of the main part of a surface treatment apparatus according to the third embodiment of the present invention. The surface treatment apparatus of this embodiment is different from that of the previous embodiment in that the substrate 2 to be treated is installed vertically to the electron beam, and the electrode 10 is provided with a plurality of electron beam extraction ports. It is in. With such a configuration, a plurality of electron beams 23 can be introduced into the reaction vessel 1, and a wide plasma region can be formed. Therefore, even if the substrate 2 to be treated has a large diameter, a uniform surface treatment can be performed.

In the surface treatment apparatus of this embodiment, since the substrate 2 to be treated is installed perpendicularly to the electron beam, the substrate 2 to be treated may be directly irradiated with the electron beam. To prevent this, an electric potential that overcomes the acceleration energy of electrons may be applied to the support 3. Further, when the substrate 2 to be processed is irradiated with an electron beam, the temperature of the substrate 2 to be processed rises. Therefore, in order to keep the temperature of the substrate 2 to be processed at room temperature, it is necessary to cool it.

When a large-diameter substrate 2 is to be processed by a surface treatment apparatus in which the substrate 2 to be processed is installed parallel to the electron beam, as shown in FIG. The electrode 10a having an elliptic outlet for the electron beam 23 may be used so that the sheet has a sheet shape. By using such an electrode 10a, a wide plasma region can be formed without causing a decrease in electron density of the electron beam, and the large-diameter substrate 2 can be uniformly processed.

Further, in order to diverge the electron beam introduced into the reaction vessel, an additional electrode 22 is provided in the reaction vessel as shown in FIG. 13, and the additional electrode 22 has a polarity as shown in FIG. When the voltage of 2 is applied, the electron beam 23 is diffused and an electron beam 23a having a wide beam diameter can be formed. By using such an electron beam 23a,
Uniform plasma (ions) can be formed in the reaction vessel.
If necessary, the shape of the electron beam 23 may be changed (diffused) by an electric field instead of a magnetic field, or the electron beam 23 may be swept on the substrate to be processed by an electromagnetic field.

In order to carry out ionization efficiently, it is effective to use a magnetic field. That is, FIG. 14 (a)
A magnetic field is formed by using a multi-pole magnet 35 composed of a plurality of rod-shaped magnets as shown in FIG.
Place within 5.

In order to form a film on a large-area substrate to be processed with good uniformity, as shown in FIG. 15, the electron beam 23 and the substrate to be processed 2 are supported while maintaining a parallel relationship. It is also effective to rotate or scan the table 3.

FIG. 16 is a schematic diagram showing a schematic structure of a surface treatment apparatus according to a fourth embodiment of the present invention. FIG. 16 (a) is a schematic view seen from above the apparatus, and FIG. 16 (b) is the apparatus. It is the schematic diagram seen from the side surface. In the figure, reference numeral 40 denotes an electron beam generator, which is specifically the same as the electron beam generator (vacuum container 5, 6, electrodes 10 to 12, etc.) of the thin film device of FIG. Further, in the figure, 39 designates a clamp for pressing and fixing the substrate 2 to be processed.
The substrate 2 to be processed is securely fixed to the end portion of the support base 3 on the introduction side of the electron beam 23 of the support base 3 by 9. The substrate 2 to be processed is arranged so that its surface is parallel to the electron beam 23. Also, the other end of the support base 3 and the electron beam 23
The distance d from the substrate 2 to be processed, which is the most downstream side, is 50 to 2
It is preferably about 00 mm. Clamp 3
Instead of 9, the substrate 2 to be processed may be fixed by using an electrostatic chuck or the like. In addition, the support base 3 includes the variable DC voltage source 2
In addition to 9, the AC voltage source 24 is also connected to prevent charge-up of the substrate 2 to be processed.

For example, in order to perform the sputter etching of a polycrystalline silicon film formed on an 8-inch silicon wafer by this surface treatment apparatus, Ar is introduced from the gas inlet port 20.
The gas is introduced into the reaction vessel 1 at a flow rate of about 5 to 50 sccm, and the variable DC voltage source 29 causes 50 to 10 sccm.
A direct current voltage of about 0 V is applied to the support base 3. At this time,
Exhaust is performed from the exhaust port 4 so that the pressure in the reaction container is about 1 to 100 mPa.

FIG. 17 is a diagram showing the relationship between the sputter etching rate in the sputter etching and the position of the silicon wafer (wafer position). As shown in FIG. 16A, the wafer position x is determined by setting the point at the most downstream of the electron beam 23 as the origin. Non-uniformity of sputter etching rate is within ± 200 mm
It was as small as about 5%.

Further, the conventional apparatus of FIG. 26, that is, the size of the support base 84 is 10 mm larger than that of an 8-inch silicon wafer.
When the same sputter etching was carried out using a surface treatment apparatus having a size of only about 20 mm and an 8-inch silicon wafer placed on the central portion of the support table 84, the sputter etching rate was as shown in FIG. Became. That is, the nonuniformity of the sputter etching rate was as large as more than ± 30% in the 200 mm region.

From the above results, it is understood that the uniformity of the sputter etching rate can be improved by placing the substrate 2 to be processed on the end portion of the support base 3 on the upstream side of the electron beam as in this embodiment. It is considered that the improvement of the uniformity of the sputter etching rate corresponds to the uniformity of the plasma density on the substrate 2 to be processed, and the improvement of the uniformity means that the substrate 2 to be processed is the end portion of the supporting table 3 on the upstream side of the electron beam 23. It is considered that the change in the inclination of the electric field created by the end portion of the supporting table 3 on the downstream side of the electron beam 23 is alleviated by arranging the same.

In this embodiment, the case where the number of the support bases 3 is one has been described, but as shown in FIG.
The same effect can be obtained by arranging a plurality of support bases 3 in a polygonal shape so as to surround the. Moreover, since a plurality of substrates to be processed can be processed at the same time, productivity is improved.

In the case of the polygonal arrangement, there is a risk of dropping when the substrate 2 to be processed is fixed to the support base 3 due to the influence of gravity. In order to avoid this, for example, a rotation mechanism is provided on the support base 3 to fix the base material 2 to be processed on the support base 3 at a position where the base material 2 to be processed does not drop, or the reaction vessel 1 is made vertical and is a vacuum chuck. You can fix it with.

Next, a method of forming a TiN film according to the fifth embodiment of the present invention will be described. The surface treatment apparatus used in this embodiment may be of the type shown in FIG. 1 or the type shown in FIG.

First, as shown in FIG. 20 (a), the substrate 2 to be treated having a groove formed on the surface thereof is housed in a reaction vessel, and subsequently, the pressure in the reaction vessel is set at 10 ⁻⁴ Torr or less, For example, the pressure is reduced to 10 ⁻⁶ Torr or less. After this, TiCl ₄ gas with a flow rate of about 0.1 to 1.0 sccm and a flow rate of 3
Hydrogen gas of about 0 to 50 sccm and flow rate of 10 to 50
A nitrogen gas of about sccm is introduced into the reaction container.

Then, the evacuation rate is adjusted to maintain the pressure in the reaction vessel at about 0.1 to 1.5 mTorr, introduce an electron beam into the reaction vessel, and set the support to -50.
A bias voltage of about -100 V is applied. The bias voltage is negative because the deposited species are positive ions in this embodiment.

By this method, as shown in FIG. 20B, a completely anisotropic TiN film 44 is formed on the substrate 2 to be processed. Further, according to the research conducted by the present inventors, it has been found that a film having sufficiently high directionality can be formed if the bias voltage is -50 V or less.

In this example, Ti was used as the gas containing Ti.
Although Cl ₄ gas is used, another gas containing Ti may be used.

For example, gases such as Ti [N (C ₂ H ₅ ) ₂ ] ₄ gas, Ti [N (CH ₃ ) ₂ ] ₄ gas, organic Ti gas, and halogenated Ti gas can be used. .

Here, in the case of Ti [N (C ₂ H ₅ ) ₂ ] ₄ gas, in addition to this gas, for example, the flow rate is 10 to 50.
If nitrogen of about sccm and hydrogen of about 10 to 100 sccm are used, a completely anisotropic TiN film can be formed. Similarly, in the case of Ti [N (CH ₃ ) ₂ ] ₄ gas, in addition to this gas, for example, the flow rate is 10 to 50 sccm.
Nitrogen having a flow rate of about 10 to 100 sccm may be used.

Next, a method of forming a Cu film according to the sixth embodiment of the present invention will be described.

The main difference from the case of the TiN film is that Cu (HFA) ₂ is put in the reaction container and the reaction container
It is to heat the film to about 100 ° C. and to introduce a H ₂ gas of about 10 to 100 sccm as a carrier gas into the reaction container to form a film. The conditions such as the bias voltage are the same as those for the TiN film. Even with such a method, a completely anisotropic Cu film can be formed.

In this embodiment, Cu (H
FA) ₂ was used instead of Cu (DPM)
₂ , an organic Cu gas, a halogenated Cu gas or the like may be used.

[0102] For example, in the case of Cu (DPM) ₂ is placed Cu (DPM) ₂ in the reaction vessel, the reaction vessel 190
By heating to about 200 ° C. and introducing H ₂ gas of about 10 to 100 sccm as a carrier gas into the reaction vessel, a completely anisotropic Cu film can be formed.

Next, the effect of water remaining in the reaction vessel on the film quality will be described.

FIG. 21 shows the partial pressure of water remaining in the reaction vessel (residual H ₂ O partial pressure) and the specific resistance of the TiN film when the TiN film was formed by the TiCl ₄ , N ₂ and H ₂ gas system. It is a characteristic view which shows the relationship with. From FIG. 21, the specific resistance, residual H ₂ O partial pressure increases rapidly becomes approximately 10 ^-5 Torr table, it can be seen that not form a high quality TiN film with level of 10 ^-5 Torr or more. Therefore, in order to obtain a good quality TiN film, it is necessary to form the film under the condition that the residual H ₂ O partial pressure is in the order of 10 ⁻⁶ Torr or less. The same tendency was observed in the formation of TiN film and Cu film using other gases.

FIG. 22 shows the T according to the seventh embodiment of the present invention.
FIG. 6 is a process cross-sectional view showing a method for forming an iN film. This is a method of forming a TiN film using lift-off.

First, as shown in FIG. 22A, an Al film 5 having a thickness of about 100 to 500 nm is formed on a silicon substrate 51.
After forming 2, the Al film 52 and the silicon substrate 51 are etched to form a groove on the surface of the silicon substrate 51.

Next, as shown in FIG. 22B, the TiN film 53 is anisotropically formed by the method described above. That is, the TiN film 53 is selectively formed in a region other than the sidewall portion of the groove.

Next, the silicon substrate 51 is dipped in a sulfuric acid solution.
The sulfuric acid solution can dissolve Al, but cannot dissolve TiN. Therefore, the TiN film 53 on the Al film 52 is peeled off, but the TiN film 53 at the bottom of the groove is left. Therefore, as shown in FIG. 22C, the TiN film 53 can be selectively formed at the bottom of the groove.

FIG. 23 shows C according to the eighth embodiment of the present invention.
FIG. 6 is a process cross-sectional view showing a method for forming u wiring. This is a method for forming Cu wiring using etch back.

First, as shown in FIG. 23A, after forming a groove on the surface of the silicon substrate 61, the TiN film 6 having a thickness of 50 nm is formed in the region other than the side wall of the groove by the above-mentioned method.
2. Cu film 63 is continuously formed. The Cu film 63 is formed using, for example, Cu (DPM) ₂ and H ₂ .

Next, as shown in FIG. 23B, a resist 64 is applied on the entire surface. Then, as shown in FIG. 23C, the resist 64 is subjected to reactive ion etching to such an extent that the TiN film 62 and the Cu film 63 outside the groove are exposed and the TiN film 62 and the Cu film 63 in the groove are not exposed. Etching.

Next, as shown in FIG. 23D, the silicon substrate 61 is dipped in an H ₂ SO ₄ solution to selectively remove the Cu film 63 outside the groove, and then the H ₂ O ₂ solution is used. Ti
The N film 62 is removed. After that, the remaining resist 64 is removed by an organic solvent as needed.

By such a method, Cu wiring can be formed without etching the Cu film 63.

FIG. 24 shows C according to the ninth embodiment of the present invention.
FIG. 6 is a process cross-sectional view showing a method for forming u wiring. This is also a Cu wiring forming method using etch back.

First, as shown in FIG. 24A, as in the previous embodiment, a silicon substrate 61 having grooves formed on its surface is formed.
A TiN film 62 and a Cu film 63 are anisotropically continuously formed on top. The film thickness of the TiN film 62 is, eg, about 50 nm. The Cu film 63 is formed by, for example, Cu (HFA)
₂ , using H ₂ .

Next, as shown in FIG. 24 (b), S is formed on the entire surface.
An iO ₂ film 65 is formed. The SiO ₂ film 65 is formed using, for example, TEOS and O ₃ .

Next, as shown in FIG. 24 (c), SiO ₂
The film 65 is removed to the same extent as in the case of the resist 64 of the previous embodiment by reactive ion etching.

Next, as shown in FIG. 24 (d), the silicon substrate 61 is dipped in an H ₂ SO ₄ solution to remove Cu except the bottom of the groove.
After removing the film 63, the silicon substrate 61 is transferred to an H ₂ O ₂ solution to remove the TiN film 62 outside the groove.

With such a method, as in the previous embodiment, the Cu wiring can be formed without etching the Cu film 63.

The present invention is not limited to the above-described embodiment. For example, as in the surface treatment apparatus of the fourth embodiment, the substrate to be treated is provided at the end of the support table on the upstream side of the electron beam. The clamps for fixing may be provided on the support base of the surface treatment apparatus of the first embodiment, and the above embodiments may be appropriately combined.

Besides, various modifications can be made without departing from the scope of the present invention.

[0121]

As described in detail above, according to the surface treatment apparatus of the present invention, the potential of the surface treatment chamber and the potential of the support are independently controlled, so that the inner wall of the surface treatment chamber is sputtered by ions. It is possible to prevent the substrate to be treated from being contaminated due to.

Further, according to the other surface treatment apparatus of the present invention, since the substrate to be treated is unevenly distributed on the supporting base on the electron generating means side, compared with the case where the substrate to be processed is located at the center of the supporting base. As a result, the uniformity of the plasma distribution density on the substrate to be treated is improved, and the substrate to be treated can be surface-treated uniformly.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a surface treatment apparatus according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between kinetic energy of incident electrons and generation efficiency of positive ions in a gas phase.

3A to 3C are process cross-sectional views showing a method of forming an amorphous silicon film using the surface treatment apparatus of FIG.

FIG. 4 is a diagram showing how the pedestal current and the reaction wall current change into a potential difference between the pedestal and the reaction vessel.

FIG. 5 is a characteristic diagram showing the relationship between the H ₂ amount, the deposition rate of the W film, and the specific resistance of the W film.

FIG. 6 is a diagram showing a relationship between step coverage and pressure.

FIG. 7 is a characteristic diagram showing the relationship between the voltage applied to the support and the current flowing through the support.

FIG. 8 is a diagram for explaining a film thickness ratio used for evaluation of step coverage.

9A to 9C are process sectional views showing a surface oxidation method using the surface treatment apparatus of FIG.

FIG. 10 is a schematic diagram showing a main configuration of a surface treatment apparatus according to a second embodiment of the present invention.

FIG. 11 is a schematic diagram showing a main configuration of a surface treatment apparatus according to a third embodiment of the present invention.

FIG. 12 is a view for explaining an electrode used for a large-diameter substrate to be processed.

FIG. 13 is a view for explaining a method of diffusing an electron beam introduced into a reaction container.

FIG. 14 is a diagram for explaining a method for efficiently performing ionization.

FIG. 15 is a diagram for explaining a method of forming a film with good uniformity.

FIG. 16 is a schematic diagram showing a schematic configuration of a surface treatment apparatus according to a fourth embodiment of the present invention.

FIG. 17 is a diagram showing the relationship between the patterner etching rate and the wafer position by the surface treatment apparatus of the present invention.

FIG. 18 is a view showing a relationship between a patterner etching rate and a wafer position by a conventional surface processing apparatus.

FIG. 19 is a view showing an arrangement example of support bases when a plurality of support bases are used.

FIG. 20 is a diagram showing a deposited shape of a TiN film obtained by the method for forming a TiN film according to the fifth embodiment of the present invention.

FIG. 21 is a characteristic diagram showing the relationship between residual H ₂ O partial pressure and specific resistance.

FIG. 22 is a process sectional view showing the method of forming the TiN film according to the seventh embodiment of the present invention.

FIG. 23 is a process sectional view showing the method of forming the Cu wiring according to the eighth embodiment of the present invention.

FIG. 24 is a process sectional view showing the method of forming the Cu wiring according to the ninth embodiment of the present invention.

FIG. 25 is a schematic diagram showing a schematic configuration of a conventional electron beam excitation plasma etching apparatus.

FIG. 26 is a schematic diagram showing a schematic configuration of another conventional electron beam excitation plasma etching apparatus.

FIG. 27 is a view for explaining a problem of the conventional film forming method.

FIG. 28 is a view for explaining a problem of another conventional film forming method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reaction container (surface treatment chamber), 2 ... Substrate to be processed, 3 ... Support base, 4 ... Exhaust port, 5 ... Second vacuum container, 6 ... First vacuum container, 7 ... Exhaust port, 8 ... Exhaust Mouth, 9 ... Insulator, 10,
10a, 10b, 11, 12 ... Electrode, 13 ... Gas inlet, 14 ... Discharge gas, 15, 16, 17 ... Coil, 1
9 ... Reactive gas, 20 ... Gas inlet, 21 ... Thermoelectron emission material, 22 ... Additional electrode, 23, 23a ... Electron beam, 2
4 ... AC voltage source, 25 ... First DC voltage power source (means for controlling potential of support base), 26 ... Second DC voltage power source (means for controlling potential of surface treatment chamber), 27 ... Third DC voltage power source, 28 ... Fourth DC voltage power source, 29 ... Variable DC voltage source, 31 ... Silicon substrate, 32, 32a ... Amorphous silicon film, 33 ... SiO ₂ film, 34 ... W film, 35 ...
Multi-pole magnet, 38 ... Ar gas, 39 ... Clamp (means for fixing the substrate to be processed to the end of the support base), 40
... Electron beam generator, 41 ... Silicon substrate, 42 ... Amorphous silicon film, 43, 43a ... Oxide film, 44 ... T
iN film, 51 ... Silicon substrate, 52 ... Al film, 53 ... T
iN film, 61 ... Silicon substrate, 62 ... Al film, 63 ... T
iN film, 64 ... Resist, 65 ... SiO ₂ film.

Front Page Continuation (72) Nobuo Hayasaka No. 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Within the Corporate Research and Development Center, Toshiba Corporation (72) Haruo Okano No. 1 Komukai-shiba, Kouki-ku, Kawasaki-shi, Kanagawa Incorporated company Toshiba Research & Development Center (72) Inventor Katsuya Okumura 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Incorporated company Toshiba Tamagawa Plant (72) Inventor Kazuya Nagaseki Kitashita, Fujii-cho, Nirasaki-shi, Yamanashi Prefecture Article 2381 Address 1 Tokyo Electron Yamanashi Co., Ltd. (72) Inventor Shinji Hinomori Kitashita Fujii-cho, Nirasaki City, Yamanashi Prefecture Article 2381 Address 1 Tokyo Electron Yamanashi Co., Ltd. (72) Inventor Shuji Mochizuki Fujii-cho Kitashita, Narasaki City Yamanashi Prefecture Article 1 at 2381 Tokyo Electron Yamanashi Co., Ltd.

Claims (2)

[Claims] 1. A surface treatment chamber into which a plasma source gas is introduced, a means for controlling the potential of the surface treatment chamber, a support table provided in the surface treatment chamber for mounting a substrate to be treated, and the support. And a means for controlling the potential of the table, an electron generating means for generating electrons, a means for accelerating the electrons, guiding the accelerated electrons into the surface treatment chamber, and plasmatizing the plasma source gas. A surface treatment device characterized by the following. 2. A surface treatment chamber into which a plasma source gas is introduced, an electron generating means for generating electrons, the electrons are accelerated, and the accelerated electrons are introduced into the surface treatment chamber to discharge the plasma source gas. Means for generating plasma, a support table provided in the surface treatment chamber and having a support surface formed along the traveling direction of electrons introduced into the surface treatment chamber, means for controlling the potential of the support table, and A surface treatment apparatus comprising: a support surface on the electron generation means side;