KR20050013187A - Method and apparatus for generating a gas plasma, gas compostion for generating a plasma and method for semiconductor processing using the same - Google Patents

Abstract

PURPOSE: A method and an apparatus of generating gas plasma, a gas composition of generating plasma, and a method of fabricating a semiconductor device using the same are provided to enhance productivity by improving efficiency of generation and reducing a generating period in a plasma generating process using a remote method. CONSTITUTION: A first electric field(48a) is generated at a plasma generating member or a gas floating member(43) by an RF current supplied from a power supply unit(45). A second electric field(48b) is generated at the plasma generating member or the gas floating member by a main magnetic field forming part and an auxiliary magnetic field forming part. The first electric field and the second electric field cross at right angles within the plasma generating member or the gas floating member. The radical atmosphere is formed within the plasma generating member or the gas floating member by the first electric field and the second electric field.

Description

Gas plasma generating method and apparatus, gas composition for plasma generation and manufacturing method of semiconductor device using same {Method and apparatus for generating a gas plasma, gas compostion for generating a plasma and method for semiconductor processing using the same}

The present invention relates to a plasma generation method, an apparatus for generating the plasma, a novel gas composition for plasma formation and a semiconductor manufacturing method using the same. In particular, the present invention relates to a method for generating a plasma in a remote manner, an apparatus for generating the plasma, a gas composition for generating silicon and etching the plasma, and a semiconductor manufacturing method using the gas composition.

In recent years, with the rapid spread of information media such as computers, semiconductor devices are also rapidly developing. In terms of its function, the semiconductor device is required to operate at a high speed and to have a large storage capacity. Therefore, the semiconductor device requires high integration of a design rule of 0.15 µm or less. Therefore, the manufacturing technology of the semiconductor device has been developed into a fine processing technology such as a manufacturing technology using plasma.

The plasma is classified into an in-situ method and a remote method according to a generation method. The in-situ method is a method of generating the plasma in a chamber for performing a semiconductor manufacturing process. The remote method is a method of generating the plasma outside the chamber and then providing the plasma to the chamber. Since the in-situ method directly generates the plasma inside the chamber, the plasma may damage the substrate and the inner wall of the chamber. Therefore, in the recent semiconductor manufacturing process, the remote method of generating plasma outside the chamber is mainly adopted.

Examples of the method and apparatus for generating the plasma by the remote method are disclosed in Korean Unexamined Patent Publication No. 1998-79855, Korean Unexamined Patent Publication No. 2001-49697, US Patent No. 5,458,754 (issued to Sathrum et al.), United States of America Patent No. 6,263,830 (issued to Kamarehi et al.), Japanese Patent Laid-Open No. Hei 6-293980, Japanese Patent Laid-Open No. Hei 8-323873, and the like.

U. S. Patent No. 5,458, 754 discloses a method of generating a plasma using a magnetic field. U. S. Patent No. 6,263, 830 discloses a method of generating plasma using microwaves. By using the magnetic field or the microwave, it is possible to improve the generation efficiency of the plasma by controlling the movement of the plasma when generating the plasma.

1 is a schematic diagram showing an apparatus for generating a plasma by a conventional remote method.

Referring to FIG. 1, the plasma generating apparatus 1 includes a tube 11 through which gas flows. The tube 11 branches to the first branch tube 11a and the second branch tube 11b at the site where the source gas flows in, and the first branch tube 11a and the second branch at the site where the plasma gas is discharged. The tube 11b joins. The source gas passes through two paths P ₁ and P ₂ and is converted into gas in a plasma state.

The plasma generating apparatus 1 is provided with a magnetic field forming unit 13 which forms a magnetic field when forming the gas into plasma. The magnetic field forming portion 13 is arranged to surround the first branch tube 11a or the second branch tube 11b. The magnetic field forming unit 13 forms a magnetic field to form a plasma.

The power supply unit 15 generates a high frequency alternating current of a square wave when forming the gas into plasma to form an electric field and a magnetic field. The wire drawn out from the power supply unit 15 is arranged to surround the magnetic field forming unit 13 in the form of a coil.

When the high frequency alternating current generated by the power supply unit 15 passes through the magnetic field forming unit 13 in the form of a coil, energy is applied to gas particles and the like existing in the tube 11 to generate a gas plasma.

In the above-described conventional plasma forming apparatus 1, energy induced in the core part (site where the coil is formed) of the magnetic field forming part 13 is transmitted to the first branch tube 11a of the tube 11. An induced electric field is formed on the opposite side that functions as a secondary winding to receive energy from the core, thereby transferring energy to the gas in the second branch tube 11b.

The gas two paths (P _1, P ₂₎ is flowing through the two paths (P _1, P ₂₎ the electric field is directly caused by the power supply section 15 from on a path (P _1), another path ( In P ₂ ), an electric field induced by an electric field of the power supply unit by a coil is used. In the case of using an induced electric field, there is a power loss, and thus it is not possible to apply sufficient energy to the gas particles in the whole tube 11. Therefore, the plasma generation efficiency is lowered.

In order to supplement the plasma generation efficiency of the gas plasma generating apparatus, a large amount of gas for plasma formation is consumed. However, the mass consumption of these gases causes a rise in manufacturing costs.

In addition, many perfluorocarbon-based gases are used in semiconductor manufacturing. The perfluorocarbon-based gas is a chemically very stable and almost non-toxic material. However, the perfluorocarbon-based gas is known as a greenhouse gas causing global warming. Therefore, the use of the perfluorocarbon-based gas should reduce the emission of the perfluorocarbon-based gas into the atmosphere. The use of the perfluorocarbon-based gas can also reduce emissions to the atmosphere, and at the same time, a method that does not affect manufacturing efficiency is under development. As an example of such a method, a method of generating plasma using NF ₃ gas is proposed to generate fluorine gas radicals in cleaning in a semiconductor manufacturing process. However, since the NF ₃ gas is expensive, it causes a rise in manufacturing cost.

It is a first object of the present invention to provide a plasma generation method for improving the plasma generation rate when generating plasma by a remote method.

A second object of the present invention is to provide a remote plasma generating apparatus suitable for the above plasma generating method.

It is a third object of the present invention to provide a particularly suitable silicon etching gas composition for generating the plasma.

A fourth object of the present invention is to provide a method for manufacturing a semiconductor device using the gas composition.

1 is a schematic configuration diagram showing an apparatus for generating a plasma by a conventional remote method.

2 shows a main magnetic field and an auxiliary magnetic field formed in the magnetic field forming apparatus used in the present invention.

3 is a schematic view showing an example of a plasma forming apparatus according to an embodiment of the present invention.

4 is a conceptual view illustrating a principle of generating plasma in the plasma generating member according to the present invention.

5 is a graph showing particle motion in the plasma generating member according to the present invention.

6 is a schematic perspective view showing a plasma forming apparatus according to an embodiment of the present invention.

7 is a schematic perspective view showing a plasma forming apparatus according to another embodiment of the present invention.

8 is a schematic perspective view showing a plasma forming apparatus according to another embodiment of the present invention.

9 is a block diagram illustrating an example of a semiconductor manufacturing apparatus according to the present invention.

10 illustrates an etching apparatus according to an embodiment of the present invention.

FIG. 11 is a schematic perspective view illustrating in more detail the shower head shown in FIG. 10.

12 is a graph illustrating measurement of reaction by-products generated by using the gas plasma of Comparative Example 1. FIG.

FIG. 13 is a graph showing the measurement of reaction by-products generated using the gas plasma of Example 2.

FIG. 14 is a graph illustrating decomposition efficiency of NF ₃ gas according to gas flow rate change in the plasma generating apparatus of FIG. 1.

FIG. 15 is a graph illustrating decomposition efficiency of NF ₃ gas according to a change in gas flow rate when NF ₃ gas is used in the plasma generating apparatus of FIG. 3.

In order to achieve the first object of the present invention, the present invention comprises the steps of: forming a main-magnetic field having an axial direction and an auxiliary-magnetic field having a direction parallel to the axial direction;

Providing electric power such that an alternating current is applied to a path in the region between the main and sub-magnetic fields; And

It provides a plasma generating method comprising the step of generating a gas plasma by flowing a gas in the same path as the path to which the power is applied.

The first object of the present invention described above,

Forming a magnetic field having an axial direction;

Flowing gas in a region of the magnetic field in a first direction, the direction perpendicular to the magnetic field; And generating a plasma from the gas by applying an electric field in a second direction different from the first direction to the gas.

In order to achieve the second object of the present invention described above, the present invention

Magnetic field forming means for forming a main magnetic field having an axial direction and an auxiliary magnetic field having a direction parallel to the axial direction; And

Plasma generating means for flowing a gas in an area between the main magnetic field and the auxiliary magnetic field, and generating a plasma from the gas by applying an alternating current to the gas in the same direction as the flow direction of the gas; Provided is a plasma generating device.

In order to achieve the third object of the present invention described above, the present invention provides a gas composition for plasma generation comprising a C ₃ F ₈ gas, oxygen gas and argon gas.

In order to achieve the fourth object of the present invention described above,

Generating a gas plasma from a mixed gas of C ₃ F ₈ gas, oxygen gas, and argon gas through a remote plasma method; And

It provides a plasma etching method comprising the step of etching the target object using the gas plasma.

According to the present invention, it is possible to effectively control the behavior of the gas plasma through the main magnetic field and the auxiliary magnetic field. In addition, by applying the high frequency alternating current power in the same path as that in which the gas flows, free electrons for ionizing the gas may be effectively accelerated. Therefore, an increase in the generation efficiency of the plasma can be expected.

In addition, the gas composition for plasma generation according to the present invention is inexpensive and exhibits high plasma generation efficiency in a small amount, thereby greatly reducing the cost of the semiconductor manufacturing process.

Hereinafter, the present invention will be described in detail with reference to the drawings.

Plasma Formation Method And Apparatus

2 shows a main magnetic field and an auxiliary magnetic field formed in the magnetic field forming apparatus used in the present invention.

Referring to FIG. 2, the main magnetic field forming member 20 forms a main magnetic field 23 having an axis 21 direction (x direction in coordinates) of the main magnetic field forming member 20. A pair of first and second auxiliary magnetic field forming members 20a and 20b are provided symmetrically in parallel with the main magnetic field forming member 20. The first and second auxiliary magnetic field forming members 20a and 20b form an auxiliary magnetic field 25 having a direction parallel to the direction of the axis 21.

A repulsive force acts between the main magnetic field 23 and the auxiliary magnetic field 25, and the axis () is formed in the space between the main magnetic field forming member 20 and the first and second auxiliary magnetic field forming members 20a and 20b. 21) magnetic flux density increases in the direction.

The auxiliary magnetic field 25 is preferably formed symmetrically about the main magnetic field (23). As shown, although the auxiliary magnetic field 25 may be formed using the pair of first and second auxiliary magnetic field forming members 20a and 20b, two pairs of the auxiliary magnetic field forming members may be used, or In some cases, it can also be formed using more pairs of auxiliary magnetic field forming member. Preferably, one or two pairs of auxiliary magnetic field forming members are used to form an auxiliary magnetic field symmetrically.

A secondary electric field is formed between the main magnetic field 23 and the auxiliary magnetic field 25 by a magnetic field in the z axis direction. The gas flows to pass between the main magnetic field 23 and the auxiliary magnetic field 25, and is provided to flow the gas in the z-axis direction in which the secondary electric field is formed.

3 is a schematic view showing an example of a plasma forming apparatus according to an embodiment of the present invention.

Referring to FIG. 3, the plasma forming apparatus 4 includes a magnetic field forming unit 41 that forms a magnetic field when forming a plasma. The magnetic field forming portion 41 is composed of a main magnetic field forming portion 41a and a pair of auxiliary magnetic field forming portions 41b and 41c. The main magnetic field forming portion 41a forms a main magnetic field having an axial direction, and the auxiliary magnetic field forming portions 41b and 41c form an auxiliary magnetic field having a direction parallel to the axial direction.

The magnetic field forming unit 41 may be formed using a permanent magnet material such as ferrite. However, an electromagnet can also be used as needed. Preferably, the main magnetic field and the sub-magnetic field are formed by a permanent magnet composed of a material such as ferrite. The ferrite has high magnetic permeability in the frequency range of about tens to 500 KHz. The power supply unit 45 supplies a sinusoidal current having a low frequency of 350 KHz to 13.56 MHz, preferably 400 KHz at a high power of 1,5 to 10 KW, preferably 6 to 8 KW. In particular, the above conditions are advantageous for gas decomposition such as C ₃ F ₈ .

The plasma forming apparatus 4 includes a plasma generation and gas flow member 43 and a power supply unit 45 surrounding the main magnetic field forming portion 41a in a coil shape. The plasma generation and gas flow member 43 is supplied with a high frequency current from the power supply 45. As illustrated, the plasma generating and gas flow member 43 has a pipe shape so as to pass a region in which magnetic flux is concentrated between the main magnetic field forming portion 41a and the auxiliary magnetic field forming portions 41b and 41c. Here, the pressure in the plasma generation and gas flow member 43 is 500 mTorr to 8 Torr, preferably 1 to 2 Torr. According to this embodiment, since a high power power source is used and the plasma density is high due to the shape of the tube, the decomposition rate is high and advantageous even in a low pressure state in the above range.

In the plasma forming apparatus 4 of FIG. 3, a high frequency alternating current power is directly applied to the plasma generating member or the gas flow member 43 so that an electric field is generated directly on the plasma generating member or the gas flow member 43. This is different from the conventional plasma generating apparatus 1 of FIG. 1 in which an electric field induced through the magnetic field forming unit 13 in the tube 11 is generated.

The present invention applies the principle of the single winding transformer instead of the principle of the existing lottery transformer. It is known that lottery transformers are 30 to 50% lower in efficiency than single winding transformers. Therefore, applying the principle of the single winding transformer as shown in Figure 3 can improve the efficiency.

4 is a conceptual view illustrating a principle of generating plasma in the plasma generating member according to the present invention.

Referring to FIG. 4, the primary electric field 48a is generated in the plasma generating member or the gas flow member 43 by the high frequency current supplied from the power supply unit 45. In addition, a secondary electric field 48b is generated in the plasma generating member or the gas flow member 43 by the main magnetic field forming portion 41a and the auxiliary magnetic field forming portions 41b and 41c. The primary electric field 48a and the secondary electric field 48b are formed to be substantially 90 ° to each other in the plasma generating member or the gas flow member 43.

A radical atmosphere is formed in the plasma generating member or the gas flow member 43 by the primary electric field 48a and the secondary electric field 48b which are perpendicular to each other, and as shown in FIG. 4, the particles are spirally formed. Do an acceleration exercise. 5 is a graph showing particle motion in the plasma generating member according to the present invention. In FIG. 5, the vertical axis represents the velocity (V) of the particles, and the horizontal axis represents the time (t). Referring to FIG. 5, the particles are accelerated by the primary electric field 48a and the secondary electric field 48b and spirally move in the gas traveling direction.

Referring to FIG. 3 again, the plasma forming and gas flow member 43 may be provided with an electric field applied to a region between the main magnetic field forming portion 41a and the auxiliary magnetic field forming portions 41b and 41c. A conductive pipe 42 is provided to allow the gas to transition into the plasma state.

The conductive pipe 42 is made of a conductive metal such as aluminum or an aluminum alloy, for example. When a high frequency current is applied to both ends of the conductive pipe 42, the high frequency alternating current passes through a region between the main magnetic field forming portion 41a and the auxiliary magnetic field forming portions 41b and 41c to form the main magnetic field forming portion ( The magnetic flux between 41a) and the auxiliary magnetic field forming portions 41b and 41c passes through the dense region. The high-frequency alternating current passing through the region where the magnetic flux is concentrated passes generally in a direction perpendicular to the direction of the static magnetic field formed by the main magnetic field forming portion 41a and the auxiliary magnetic field forming portions 41b and 41c.

Then, an electric field is formed in the plasma forming and gas flow member 43, and the gas flowing in the plasma forming and gas flow member 43 is ionized to form a plasma. As shown, the conductive pipe 42 is formed to surround the main magnetic field forming portion 41a in a coil shape. Therefore, the gas flowing inside the conductive pipe 42 also has a coil-shaped flow path in the main magnetic field forming portion 41a. The current flows through the conductive pipe 42, and the gas flows along the inside of the conductive pipe 42, so that the gas flows in the same path as that of the electric power. Since power is applied as a sinusoidal high frequency alternating current, the current is applied in the forward or reverse direction with respect to the flow direction of the gas.

The gas supply side of the conductive pipe 42 is provided with a gas supply pipe 42a for supplying gas to the conductive pipe 42 from a gas supply source existing outside the region where the magnetic field is formed. In addition, a plasma drawing tube 42b for extracting and providing the plasma generated from the conductive pipe 42 to the semiconductor manufacturing apparatus existing outside the region where the magnetic field is formed is the outlet side of the conductive pipe 42. Is provided.

The connection between the gas supply pipe 42a and the plasma outlet pipe 42b and the conductive pipe 42 is connected by pipe connection members 44a and 44b. The pipe connecting members 44a and 44b are made of an insulator such as plastic or an insulating ceramic material. Accordingly, the current flowing through the conductive pipe 42 is prevented from leaking into the gas supply pipe 42a or the plasma drawing pipe 42b.

6 is a schematic perspective view showing a plasma forming apparatus 50 according to an embodiment of the present invention.

Referring to FIG. 6, a main-magnetic field forming portion 50a having an axial direction is located at the center portion. A pair of sub-magnetic field forming portions 50b and 50c are disposed symmetrically with respect to both sides of the main-magnetic field forming portion 50a. The sub-magnetic field forming portions 50b and 50c are arranged in parallel in the axial direction of the main-magnetic field forming portion 50a. By arranging the sub-magnetic field forming portions 50b and 50c in this way, the magnetic flux density of the magnetic field near the main magnetic field forming portion 50a is increased.

Plasma forming and gas flow members 51 are disposed in a spiral path surrounding the main-magnetic field forming portion 50a. At this time, the plasma forming and gas flow member 51 is located in the magnetic field regions of the main-magnetic field forming portion 50a and the sub-magnetic field forming portions 50b and 50c.

The main-magnetic field forming portion 50a and the sub-magnetic field forming portions 50b and 50c form a static magnetic field. That is, the main-magnetic field forming portion 50a forms a main-magnetic field having an axial direction, and the sub-magnetic field forming portions 50b and 50c form a pair of sub-magnetic fields having a direction parallel to the axial direction. .

One end of the plasma forming and gas flow member 51 is connected to a power supply unit 55 for supplying a high frequency current. High-frequency alternating current power is directly applied to the plasma generating and gas flow member 51 so that an electric field is generated directly on the plasma generating member or the gas flow member 43.

7 is a schematic perspective view showing a plasma forming apparatus 60 according to another embodiment of the present invention.

Referring to FIG. 7, a main-magnetic field forming part 60a having an axial direction is disposed at the center portion. The sub-magnetic field forming portions 60b, 60c, 60d, and 60e are disposed symmetrically with respect to both sides of the main-magnetic field forming portion 60a. That is, the sub-magnetic field forming portions 60b, 60c, 60d, and 60e are arranged in two pairs at an angle of 90 on all sides of the main-magnetic field forming portion 60a. In addition, the sub-magnetic field forming portions 60b, 60c, 60d, 60e are disposed in parallel with the axial direction of the main-magnetic field forming portion 60a.

The plasma forming and gas flow member 61 is arranged in a spiral path surrounding the main-magnetic field forming portion 60a. The plasma forming and gas flow member 61 is positioned to pass through a magnetic flux density region between the main-magnetic field forming portion 60a and the sub-magnetic field forming portions 60b, 60c, 60d, 60e. When forming the gas plasma, the main-magnetic field forming portion 60a forms a main-magnetic field having an axial direction, and the sub-magnetic field forming portions 60b, 60c, 60d and 60e have a direction parallel to the axial direction. Forms an auxiliary-magnetic field.

6 and 7, the sub-magnetic field forming member is disposed to be symmetrically positioned in parallel with the main-magnetic field forming member. The number of auxiliary magnetic field forming members is determined in consideration of the magnetic flux density, but is not particularly limited.

In the illustrated plasma forming apparatus, the gas flows in the same path as the path through which the high frequency current is applied. Specifically, the gas flows through the inside of the pipe to which the high frequency current is applied, so that the gas flows along a path corresponding to the application path of the high frequency current.

At this time, the gas is ionized to generate a gas plasma. The gas is ionized by colliding with free electrons accelerated through an electric field formed by the high frequency current.

The magnetic flux density is dense in the axial direction by the main and sub-magnetic fields. Thus, the behavior of the gas plasma is concentrated in the axial direction. In addition, since the direct electric field generated from the high frequency current is used by using the principle of the single winding transformer, the plasma generation efficiency is increased.

In the case of using the plasma generating apparatus, the plasma may be generated within 3 seconds after applying the current. Therefore, the time required to generate the plasma can be shortened.

8 is a schematic perspective view showing a plasma forming apparatus 70 according to another embodiment of the present invention.

Referring to FIG. 8, a main-magnetic field forming portion 70a having an axial direction is disposed at the center portion. The sub-magnetic field forming unit 70b is disposed at one side of the main-magnetic field forming unit 70a. In this embodiment, one auxiliary magnetic field forming portion 70b is disposed parallel to the axial direction of the main magnetic field forming portion 70a. In this embodiment, unlike in the other embodiments, an electromagnet formed by winding a coil around a permanent magnet is used. That is, the main magnetic field forming unit 70a and the auxiliary magnetic field forming unit 70b are formed using an iron core, which is a kind of magnetic material used as a path of the magnetic field lines, and surrounds the main magnetic field forming unit 70a. The coil 76 is formed to wrap. A high frequency alternator 75 is connected to the coil 76 to supply a high frequency alternating current. Then, an electromagnetic field in a direction parallel to the main magnetic field forming portion 70a is formed, and an induction magnetic field is formed by the auxiliary magnetic field forming portion 70b.

The plasma forming and gas flow member 71 according to the present embodiment is made of a conductive pipe, surrounds the main-magnetic field forming part 70a, and passes through the main magnetic field forming part 70a and the auxiliary magnetic field forming part 70b. It has a ring shape. The plasma forming and gas flow member 71 is positioned to pass through a magnetic flux density region between the main-magnetic field forming portion 70a and the sub-magnetic field forming portion 70b.

As shown, the plasma formation and gas flow member 71 has an annular shape, and part of it is insulated. Both ends are connected by a pipe connecting member 72 similar to the pipe connecting member shown in FIG. The pipe connecting member 72 is made of an insulator such as plastic or an insulating ceramic material. Thus, the current flows in the clockwise or counterclockwise direction along the ring of the plasma formation and gas flow member 71. That is, a current is supplied in parallel with the flow direction of the gas, and a current is applied in the forward or reverse direction to the flow direction of the gas, thereby forming an electric field therein to convert the flowing gas into plasma.

One end of the plasma forming and gas flow member 71 is connected to the coil 76 surrounding the main magnetic field forming part 70a through the first wire 77, and the other end is grounded through the second wire 78. It is. The plasma forming and gas flow member 71 has a gas injection port 71a formed at an upper portion thereof, and extends from a side thereof to form a gas outlet 71b.

In the plasma forming apparatus 70 according to the present embodiment, the high current generated by the power supply unit 75 is first applied to the main magnetic field forming unit 70a to form the main magnetic field and the auxiliary magnetic field, and then the plasma generating member or the gas. A high frequency AC power is applied to the flow member 71 so that an electric field is directly generated in the plasma generating member or the gas flow member 71.

The plasma generating gas is injected through the gas injection port 71a, and the magnetic field and the secondary electric field formed by the main magnetic field forming unit 70a and the auxiliary magnetic field forming unit 70b, and the plasma generating member or the gas flow member 71 are formed. It is converted into plasma gas under the influence of the primary electric field.

Also in this embodiment, gas flows in a direction parallel to the path through which the high frequency current is applied, and gas is generated by ionizing the gas. The gas is ionized by colliding with free electrons accelerated through an electric field formed by the high frequency current.

Semiconductor manufacturing process and apparatus

Hereinafter, a method of performing a semiconductor manufacturing process using the plasma generated by the remote method will be described.

3, 6 and 7, a main magnetic field having an axial direction and an auxiliary magnetic field having a direction parallel to the axial direction are formed. A conductive pipe is provided to wrap the axial direction in a spiral shape. When a high frequency current is applied to the conductive pipe, the high frequency current is applied through a path in the regions of the main magnetic field and the auxiliary magnetic field. An induction magnetic field and an induction electric field are formed by the high frequency current.

Next, gas is flowed through the conductive pipe. The gas passing through the static magnetic field region of the main magnetic field and the auxiliary magnetic field generates a gas plasma by the induced magnetic field and the induced electric field. Here, the gas used contains a fluorine atom. For example, NF ₃ gas or CxFy (x> 0, y> 0) gas. Examples of the gas of CxFy include CF ₄ , C ₂ F ₆ , C ₃ F ₈ , and the like. Preferably C ₃ F ₈ is mentioned.

The gas plasma is supplied to a chamber for performing a semiconductor manufacturing process. In this case, the chamber is located at a place spaced from the place where the gas plasma is generated. Accordingly, the gas plasma is supplied to the chamber through a plasma drawing tube provided at the outlet side of the conductive pipe, as shown in FIG.

The gas plasma is supplied to the chamber to perform various semiconductor manufacturing processes using the gas plasma. Although the manufacturing process which can be performed here is not specifically limited, It is preferable that it is an etching process, a lamination process, or a washing process.

As described above, when the gas plasma is generated by the above method and used in the semiconductor manufacturing process, an improvement in productivity can be expected. In particular, CxFy gas such as C ₃ F ₈ , which is inexpensive, can be used, which can significantly reduce the cost.

In addition, when using NF ₃ gas, the same amount of argon gas should generally be used as a carrier gas to operate at low power. However, according to the present invention, even when the amount of argon gas is reduced to about 1/3 compared to NF ₃ gas, high plasma generation efficiency is exhibited. Therefore, the efficiency of the process can be improved and the plasma ignition time can be shortened.

An example of the semiconductor manufacturing apparatus will be described in detail with reference to the drawings.

9 shows an example of a semiconductor manufacturing apparatus.

Referring to FIG. 9, the semiconductor manufacturing apparatus 80 illustrated includes a gas source 81 for providing a gas. Here, the gas is a gas containing a fluorine atom, NF ₃ or CxFy (x> 0, y> 0) gas is used. The gas is appropriately selected depending on the semiconductor manufacturing process to be performed.

The plasma generator 83 shown in FIGS. 3, 6 or 7 is connected to the gas source 81. As shown in FIG. 3, the gas source 81 is connected to the plasma generating unit 83 through a gas supply pipe.

The plasma generating unit 83 is provided with a main magnetic field forming unit for primarily forming a main magnetic field having an axial direction. In addition, the magnetic flux density of the main magnetic field in the axial direction may be further increased by further comprising an auxiliary magnetic field having an auxiliary magnetic field in a direction parallel to the axial direction. The plasma generating unit includes a conductive pipe made of a conductive material passing through the axial magnetic field.

The gas supplied through the gas supply pipe passes through the conductive pipe. When a low frequency high power AC current is applied to the conductive pipe, the gas is converted into a plasma state.

The gas (hereinafter sometimes referred to as gas plasma) 85 converted to the plasma is provided to a process chamber 87 which performs a semiconductor manufacturing process. The process chamber 87 is an etching chamber for etching films formed on a substrate or a deposition chamber for stacking films on a substrate.

In addition, a vacuum pump 89 may be provided in the process chamber 87 to form the process chamber 87 in a vacuum when the semiconductor manufacturing process is performed. The vacuum pump 89 evacuates not only the vacuum formation of the process chamber 87 but also reaction byproducts remaining in the process chamber 87.

The plasma generating unit 83 and the process chamber 87 are connected through a plasma drawing tube as shown in FIG. 3. As such, the gas plasma 85 is supplied to the process chamber 87 in a remote manner.

10 illustrates an etching apparatus 100 according to an embodiment of the present invention. Referring to FIG. 9, the etching apparatus 100 may include a remote plasma generator 101. The plasma generating unit 101 is the same as the plasma generating unit shown in FIGS. 3, 6 or 7. The etching apparatus 100 includes an etching chamber 103 and a vacuum pump 105 for forming the etching chamber 103 in a vacuum.

First, NF ₃ or CxFy (x> 0, y> 0) (preferably C ₃ F ₈ ) gas, which is a gas containing a fluorine group, is flowed into the plasma generating unit 101. At this time, the pressure is 500mTorr to 8Torr, preferably 1 to 2 Torr to include a relatively low pressure. Accordingly, the plasma generating unit 101 ionizes the gas to generate a plasma having F radicals. Specifically, a sinusoidal alternating current having a low frequency and high power is applied to the plasma generating unit 101 at a frequency of 350 KHz to 13.56 MHz, preferably 400 kHz, and at a power of 1.5 to 10 KW, preferably 6 to 8 KW. Accordingly, the free electrons and the like present in the gas flow portion are effectively accelerated. The free electrons and the like collide with the gas flowing into the gas flow part to cause the gas to be plasma. Thus, the gas is produced as a plasma having F radicals. The magnetic field forming portion of the plasma generating unit 101 effectively controls the plasma behavior.

Subsequently, the plasma having the F radical is supplied to the etching chamber 103. The etching chamber 103 is provided with a shower head 102 for injecting the plasma gas. The sour head portion 102 is provided with a plurality of injection holes 102a and 102b. For uniform spraying, the spray holes 102a and 102b of the shower head portion 102 are preferably formed on the opposite side of the inlet side and the inlet side of the etching chamber 103.

11 is a schematic perspective view of the shower head 102 in more detail. In the illustrated shower head portion 102, four injection holes 102a, 102b, 102c, and 102d are formed at regular intervals. By forming the injection holes 102a, 102b, 102c, and 102d as described above, the plasma etching efficiency can be improved by a side flow method in which gas plasma is uniformly applied toward the periphery of the wafer to be etched. have.

In the figure, the shower head portion 102 having four injection holes 102a, 102b, 102c, and 102d is shown. However, if necessary, two shower heads 102 are formed on the inlet side of the etching chamber 103 and on the opposite side of the inlet side. Or more than four injection holes.

Referring again to FIG. 10, when plasma gas is introduced into the chamber, F radicals react with materials formed on the substrate W, which is placed on the chuck 107. At this time, films are formed on the substrate W, and predetermined portions are exposed by the pattern mask. Thus, the membrane at the exposed site is etched in response to the membrane at the exposed site.

A method for cleaning the etching chamber 103 after performing an etching process will be described.

The etched substrate W is unloaded to the outside of the etching chamber 103. Next, for example, C ₃ F ₈ gas is flowed into the plasma generating unit 101. The plasma generating unit 101 ionizes the C ₃ F ₈ gas to generate a plasma having F radicals. Specifically, power of about 2,000 Watt having a frequency of about 400 kHz is applied to the plasma generating unit 101 to effectively accelerate free electrons and the like present in the gas plasma generating unit. Then, the free electrons and the like collide with the C ₃ F ₈ gas flowing in the gas plasma generating unit to plasma the gas. Thus, the gas is converted into a plasma having F radicals.

Subsequently, the plasma having the F radical is supplied to the etching chamber 103. Then, the F radical reacts with a reaction by-product such as a polymer adsorbed on the side wall of the etching chamber 103 or the like. Thus, the reaction by-products fall from the inner sidewall of the etching chamber 103. At this time, when the reaction by-products are exhausted through the vacuum pump 105, the etching chamber 103 is cleaned.

The semiconductor manufacturing apparatus including the plasma generation unit may be variously applied according to the type of the gas and the configuration of the process chamber.

The novel gas composition for plasma generation according to the present invention will be described.

The novel plasma generation gas composition according to the present invention contains C ₃ F ₈ gas as a main component. The C ₃ F ₈ gas is ionized and excited by the above-described remote plasma generating device to generate fluorine free radicals, excited radicals, anions and cations. They are transferred to the process chamber and chemically react with the residues (usually silicon oxides such as silicon oxide, silicon oxynitride, etc.) deposited on the walls of the chamber and are discharged as gaseous by-products.

In addition, the novel plasma generation gas composition according to the present invention contains oxygen gas. When C ₃ F ₈ gas is used alone in a semiconductor manufacturing process, carbon compounds are produced as process by-products. Since the carbon compound is easily deposited in a device or a tube, it is necessary to react with oxygen and remove it with a gas such as carbon dioxide.

The chemical reaction for removing silicon oxynitride using, for example, C ₃ F ₈ gas and oxygen gas is as follows.

C ₃ F ₈ + 3O ₂ + 2SiON = 2SiF ₄ + 3CO ₂ + N ₂

The reaction scheme may be changed depending on the material to be etched or removed, but in general, the appropriate flow rate of oxygen gas may be determined in consideration of the above-described chemical reaction scheme.

In this case, when the flow rate of the oxygen gas is less than twice the flow rate of the C ₃ F ₈ gas, carbon is not sufficiently converted to carbon dioxide and removed, which may cause residue of a carbon compound in the chamber. In addition, when the flow rate of the oxygen gas exceeds 5 times the flow rate of the C ₃ F ₈ gas, the generation of fluorine radicals in the plasma generating device is not preferable, which is undesirable. Thus, the oxygen gas is about 2 to 5 times, preferably about 2.5 to 4 times and most preferably about 3 times the flow rate of the C ₃ F ₈ gas.

The gas composition for plasma generation according to the present invention includes an inert gas such as argon gas as a carrier gas in order to smoothly supply the C ₃ F ₈ gas and the oxygen gas. At this time, the argon gas is preferably 3 to 15 times the flow rate of the C ₃ F ₈ gas for smooth transportation.

For example, the flow rate of C ₃ F ₈ gas is 400 to 800 sccm, preferably 600 to 700 sccm, the flow rate of argon gas is 1000 to 6000 sccm, preferably 2000 to 4000 sccm, the flow rate of oxygen gas is 1000 to 3600 sccm, preferably 1400 to 2100 sccm. Other gases are also possible at these conditions.

Formation of Plasma Using Plasma Generating Gas Composition

Example 1

Into the remote plasma generating device as shown in FIG. 6, a process gas including a 400 sccm flow rate C ₃ F ₈ gas, a 1,000 sccm flow rate oxygen gas, and a 2,000 sccm flow rate argon gas was introduced therein, and the pressure was about 0.7 Torr. The plasma was generated by applying a power of about 5,600 Watt.

Example 2

Into the remote plasma generating device as shown in FIG. 6, a process gas including a C ₃ F ₈ gas at a flow rate of 600 sccm, an oxygen gas at a flow rate of 1,800 sccm, and an argon gas at a flow rate of 4,000 sccm is introduced therein, and the pressure is about 1.1 Torr. Plasma was generated by applying power of about 6,400 Watts.

Example 3

The plasma was generated in the same manner as in Example 2 except that the pressure was changed to 1.5.

Example 4

The plasma was generated in the same manner as in Example 2 except that the flow rate of the argon gas was changed to 6,000 sccm, the pressure was changed to 3.5 Torr, and the power was changed to 6,100 Watts.

Example 5

The plasma was generated in the same manner as in Example 2 except that the flow rate of the argon gas was changed to 6,000 sccm, the pressure was changed to 6.5 Torr, and the power was changed to 6,700 Watt.

Comparative example

A process plasma containing 1,100 sccm of NF ₃ gas and 2,000 sccm of argon gas was introduced into a remote plasma generating apparatus manufactured by ASTEX company, which is an example of the apparatus shown in FIG. 1, and the pressure was about 0.8 Torr. The plasma was generated by applying a power of about 3,000 Watts.

Etch Rate Measurement

A SiON film having a thickness of about 6,000 Pa was deposited on the substrate (bare wafer) by plasma enhanced chemical vapor deposition. After the etching process was performed using the etching apparatus as shown in FIG. 9 using the gas plasma generated in Examples 1 to 5 and Comparative Example 1, the etching rate was measured. The measured etch rates are shown in Table 1 below.

Table 1

Etch Rate (ms / min) evaluation Example 1 4,408 ○ Example 2 5,077 ◎ Example 3 4,801 ○ Example 4 4,440 ○ Example 5 4,229 ○ Comparative example 4,094 △

Legend: ◎: Very good

○: excellent

△: normal

As can be seen from Table 1 above, in Examples 1 to 5, the etching efficiency of the wafer and the etching efficiency of the conventional comparative example were compared using the remote plasma, and the examples 1 to 5 were superior to the comparative example. Etching efficiency was shown. In particular, when the pressure was about 1 Torr and the oxygen gas flow rate was about three times the C ₃ F ₈ gas flow rate, the best efficiency was shown.

Cleaning test

The etching apparatus was cleaned using the gas plasma generated in Example 2 and Comparative Example. The cleaning time was determined whether or not cleaning was performed based on the oxynitride film having a thickness of 600 kPa deposited by a plasma enhanced chemical vapor deposition method. The reaction was measured by time zone by the RGA-QMS (Quardrupole mass spectrometer) (method of ionizing the generated SiF ₄ by quantification).

12 is a graph illustrating measurement of reaction by-products generated using the gas plasma of Comparative Example, and FIG. 13 is a graph illustrating measurement of reaction by-products generated using the gas plasma of Example 2. FIG.

12 and 13, the vertical axis represents ion concentration and the horizontal axis represents time (unit second).

In each figure, the peak level of SiF ₄ is significantly reduced after a certain time, and becomes the end point detection time when the reduced amount is kept constant. As shown in FIG. 13, in the case of the conventional plasma gas using NF 3, the peak level of SiF _{4, which} is a by-product of cleaning of the chamber, is maintained for a certain time and is not reduced. It is judged that cleaning is performed continuously such that the fixed SiF ₄ peak is maintained. Thus, the total cleaning time took about 1,410 seconds.

On the other hand, as shown in FIG. 13, when cleaning using the gas plasma of Example 2, the SiF ₄ peak level gradually decreases after a certain time to maintain a constant reduced value. Therefore, since no further by-products are generated by the cleaning, a certain point of the SiF ₄ level can be regarded as the end point of the cleaning. The washing time was measured at 848 seconds.

The results are summarized in Table 2 below.

TABLE 2

Comparative example Example 2 Total cleaning time in seconds 1,410 848 Used gas NF ₃ gas C ₃ F ₈ gas Flow rate (sccm) 1100 600

From the above table, the cleaning time was shortened by 562 seconds compared to the case of using NF ₃ gas in the comparative example under the same conditions, and the amount of gas was also reduced by about 45%. In addition, the process can be performed using C ₃ F ₈ gas, which is much cheaper than NF ₃ gas, resulting in significant cost savings.

Gas decomposition efficiency for the same gas

In the case of using the NF ₃ gas in the plasma generating apparatus shown in FIG. 1, the same amount of argon gas should be used as the carrier gas in order to operate at low power. Therefore, it is not possible to increase the cleaning efficiency of the plasma by using a certain amount of NF ₃ gas or more. FIG. 14 is a graph illustrating decomposition efficiency of NF ₃ gas according to gas flow rate change in the plasma generating apparatus of FIG. 1. As can be seen in FIG. 14, when the amount of NF ₃ gas is increased, the chamber pressure itself is increased so that an appropriate pressure cannot be adjusted, and the decomposition efficiency of the NF ₃ gas is initially lowered, thereby increasing the plasma ignition time. .

FIG. 15 is a graph showing the decomposition efficiency of NF ₃ gas according to the change in gas flow rate when the NF ₃ gas is used in the plasma generating apparatus shown in FIG. ₃ . As can be seen in Figure 15, a high decomposition rate of more than 95% was shown in a wide pressure range, and even if the flow rate of the NF ₃ gas to about 3000sccm showed a sufficiently high decomposition efficiency. In addition, even if the ratio of NF ₃ gas and argon gas was maintained at about 3: 1, plasma could be used without any problem.

Generally, when the amount of NF ₃ gas is large, plasma decomposition rate is low and plasma formation takes a long time. In addition, the efficiency decreases with time. However, in the plasma generating apparatus according to the present invention, since an appropriate amount of gas is required, the amount of gas is reduced, which is advantageous in terms of cost. In addition, even when using NF ₃ gas, since the decomposition rate can be maintained at about 99% even at low pressure, the amount of NF ₃ gas used can be reduced.

In addition, in the plasma generating apparatus according to the present invention, since a natural ignition is performed by argon which is an ignition gas in a low pressure state, a separate ignition device is not necessary.

According to the present invention, the plasma generation efficiency can be improved when the plasma of the remote system is formed. In addition, the time required for generating the plasma can be shortened. Accordingly, when the plasma is applied to semiconductor manufacturing, an effect of improving productivity can be expected.

In particular, since a low-cost gas such as C ₃ F ₈ gas can be used in the semiconductor manufacturing process, it can be expected to reduce the cost of the semiconductor manufacturing.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Claims (5)

Forming a magnetic field having an axial direction; Flowing gas in a region of the magnetic field in a first direction, the direction perpendicular to the magnetic field; And And generating a plasma from the gas by applying an electric field in a second direction different from the first direction to the gas. The plasma generation method of claim 1, further comprising: forming at least one pair of auxiliary magnetic fields symmetrically with respect to the magnetic field in parallel with the magnetic field to increase the magnetic flux density in the region through which the gas passes. Way. The plasma generating method of claim 1, wherein the electric field is formed by applying an alternating current having a low frequency and high power. The method of claim 3, wherein the alternating current is applied in the forward or reverse direction in the same direction as the flow direction of the gas. The method of claim 1, wherein the first direction and the second direction are perpendicular to each other.