JP3197739B2 - Plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus.

[0002]

2. Description of the Related Art A plasma processing apparatus generates a plasma by performing a vacuum discharge in a processing vessel in which a processing gas is present.
The plasma processing apparatus is configured to perform a predetermined process on the object using the plasma. This plasma processing apparatus has been widely used in a semiconductor manufacturing process, such as a sputtering process, an ashing process, a CVD process, or an etching process.

As such a plasma processing apparatus, for example, a plasma processing apparatus having parallel plate electrodes has been conventionally known. The plasma processing apparatus includes a processing container that forms a reduced-pressure space by evacuation, a lower electrode that is disposed below the processing container and holds a semiconductor wafer as a processing target, and faces the lower electrode. It is provided with an upper electrode provided and a high-frequency power supply for generating a plasma by applying a high-frequency voltage between the two electrodes. In addition, a receiving port for receiving a processing gas is formed on the upper surface of the upper electrode, and a gas supply hole for supplying the received gas into the processing container is formed on the lower surface in a dispersed manner. Supply gas for processing into the processing vessel,
The gas after processing is configured to be exhausted from an exhaust port formed in the processing container.

Accordingly, in order to perform plasma processing on a semiconductor wafer using the above-described plasma processing apparatus, a plasma processing gas is supplied from a gas supply hole into a processing vessel reduced in pressure to a low vacuum, and a lower electrode is supplied by a high frequency power supply. A high-frequency voltage is applied between the upper electrode and the upper electrode to generate plasma by a discharge between them, and a predetermined plasma process is performed on the semiconductor wafer on the lower electrode 2 by the active species of the plasma. I have.

[0005]

However, in the case of a conventional plasma processing apparatus having a parallel plate electrode structure as described above, a high-frequency voltage is applied to upper and lower electrodes in a processing vessel, and a voltage is applied between these electrodes. Since the plasma is generated by discharging, the discharge gas pressure is restricted by the relationship between the discharge starting voltage, the distance between the electrodes and the gas pressure, and the gas pressure for stably generating the plasma between the upper and lower electrodes is There is a problem that a pressure of about 0.5 Torr is the limit of the degree of vacuum, and plasma cannot be generated under a higher vacuum. In recent years, semiconductor wafers have become increasingly ultra-fine and require finer and deeper grooves, etc., but conventional plasma processing equipment has a relatively high processing pressure, so that active species are not compatible with each other. As a result, there is a problem that it is not possible to travel straight, which hinders the fine processing of a semiconductor wafer, and it is not possible to meet such recent demands for fine processing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can generate high-density plasma even under a high vacuum, which cannot generate plasma with a parallel plate electrode structure. It is an object of the present invention to provide a plasma processing apparatus capable of performing uniform ultrafine processing on an object to be processed without contaminating the object.

[0007]

According to a first aspect of the present invention, there is provided a plasma processing apparatus which supports an object to be processed by a processing gas supplied into a processing container and includes a processing object in the processing container. A support provided, and a gas supply unit provided on a surface facing the support, and applying a high-frequency voltage to generate a high-frequency magnetic field in a direction along the object in synchronization with the high-frequency voltage. A plurality of individually independent guiding means for forming and plasma-treating the processing gas are arranged along the outer periphery of the processing vessel, and
A high-frequency power supply for applying high-frequency power with a phase difference in sequence is connected to each of the inducing means .

[0008] The plasma processing apparatus according to claim 2 of the present invention is the invention according to claim 1, the induction
An inductive antenna is provided as a means .

According to a third aspect of the present invention, in the plasma processing apparatus according to the first or second aspect, each of the plurality of guiding means generates an electromagnetic wave.
It is characterized by the following.

According to a fourth aspect of the present invention, in the plasma processing apparatus according to any one of the first to third aspects, the processing container is connected to the plurality of guiding means.
At least a part of the wall of the processing vessel
It is characterized by being formed of an electrically conductive material .

According to a fifth aspect of the present invention, in the plasma processing apparatus according to any one of the first to fourth aspects, the plurality of inducing means are connected via an electrostatic coupling preventing member. Te is characterized in that provided in the processing vessel.

According to a sixth aspect of the present invention, in the plasma processing apparatus according to any one of the first to fifth aspects, the gas supply unit is configured to correspond to the object to be processed.
It is characterized by having a plurality of gas supply holes evenly distributed on the surface made of the opposite dielectric material .

[0013]

According to the first aspect of the present invention, the processing gas is supplied from the gas supply unit into the processing container, and the processing gas is individually supplied.
With a plasma processing gas by the individual induction means by applying a high frequency voltage with a sequential <br/> phase difference from each of the high frequency power source to the stand by a plurality of guide means, the object to be processed by the individual guiding means A high-frequency magnetic field having a phase difference in a direction along the surface to be processed forms a rotating magnetic field, so that the plasma of the processing gas can be densified and homogenized.

According to the invention described in claim 2 of the present invention, in the invention described in claim 1, the plurality of leads are provided.
Inductive antennas are provided as means, respectively.
Electromagnetic waves can be emitted from the antenna into the processing container .

According to a third aspect of the present invention, in the first or second aspect,
Each of the plurality of guiding means generates an electromagnetic wave,
The processing gas in the processing vessel is turned into plasma by electromagnetic waves
Can be .

[0016] According to the invention described in claim 4 of the present invention, the invention according to any one of claims 1 to 3, the processing chamber faces distribution to the plurality of guide means
At least a part of the wall surface of the placed processing vessel is dielectric
Since it is made of material, high-frequency magnetic
Creates a high-frequency rotating magnetic field inside without shielding the field
Can be done .

According to a fifth aspect of the present invention, in the first aspect of the present invention, the plurality of guiding means are connected via an electrostatic coupling preventing member. In the processing container, the electrostatic coupling component of, for example, electromagnetic waves from the plurality of inducing means is prevented from entering the processing container by the electrostatic coupling prevention member to prevent charging on the inner surface of the processing container. Can be.

According to the invention described in claim 6 of the present invention, in the invention described in any one of claims 1 to 5, the gas supply unit faces the object to be processed.
Since it has a plurality of gas supply holes uniformly distributed on the surface made of a dielectric material, the inner surface in contact with the plasma generation region is made of a dielectric material, and electromagnetic waves generated from a plurality of induction means are provided.
The waves act uniformly on the processing gas replenished from the gas supply holes without being disturbed in the plasma generation region, whereby a uniform plasma can be generated.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS. As shown in FIGS. 1 and 2, the plasma processing apparatus of the present embodiment includes a processing container 11 that can seal the inside from the outside and maintain a high vacuum, and is disposed in the processing container 11 and serves as a processing target. And a conductive susceptor 12 for holding the semiconductor wafer W horizontally with the surface to be processed facing up. A plurality of inducing means for generating a high-frequency rotating magnetic field B described later, for example, four coils 13A are provided on the outer periphery of the processing container 11. The center axis of the processing chamber 11, the rotation center axis of the high-frequency rotating magnetic field B, and the semiconductor wafer W
Is preferably arranged such that the members described later coincide with each other.

As shown in FIG. 1, the processing vessel 11 includes an application section 11A for applying the high-frequency rotating magnetic field B.
And a processing unit 1 connected below the application unit 11A and configured to process the semiconductor wafer W on the susceptor 12 by plasma with a high frequency rotating magnetic field.
1B. The application unit 11A is, for example, quartz,
The upper end and the lower end are each formed of a cylindrical body formed of an insulating material or a dielectric material such as ceramics, and the upper end and the lower end thereof are respectively opened. The processing section 11B is formed of a conductive material such as aluminum, and has a lower end. It consists of a closed cylinder. This processing unit 11B
An opening formed in accordance with the inner diameter of the application unit 11A is provided on the upper surface, and the application unit 11A is attached to the opening via a seal member 14 such as an O-ring so as to keep the inside airtight. I have. The inner surface of the processing unit 11B is anodized and grounded to maintain a ground potential. Further, a gas supply unit 11C for supplying a processing gas is attached to the upper end opening of the application unit 11A via a seal member 14 such as an O-ring, and the inside of the gas supply unit is maintained by the seal member 14. ing. The gas supply unit 11C is paired with the wafer W.
The facing surface is formed of a dielectric material such as quartz or ceramics, and the other portion is formed as a flat hollow disk of a conductive material such as aluminum. A gas receiving port 11D is formed at the center of the upper surface of the gas supply unit 11C, and the processing gas supplied from the gas receiving port 11D is evenly distributed in the processing container 11 on the lower wall made of a dielectric material. Supply gas supply hole 1
1E are dispersed and formed. These gas supply holes 11 </ b> E can be formed in various forms, as required, in inner diameter and arrangement. The processing unit 11B is provided with an exhaust port 11F that communicates with an exhaust unit 50 such as a vacuum pump, and is configured to exhaust the processed gas and the like from the exhaust port 11F. By providing a plurality of exhaust ports 11F in the processing unit 11B so as to be rotationally symmetric, it is possible to suppress the bias of the plasma in the processing unit 11B. This gas supply unit 11C is grounded similarly to the processing unit 11B.

The susceptor 12 is connected to the processing unit 11
It is made of anodized aluminum similarly to B and the gas supply unit 11C. The susceptor 12 includes a capacitor 15 and a matching circuit 16.
A high-frequency power supply 17 for applying a high-frequency voltage of, for example, 13.56 MHz is connected, and the susceptor 12 is configured to be negatively self-biased by the high-frequency voltage during plasma processing. This bias voltage can be adjusted by appropriately controlling the applied voltage from the high-frequency power supply 17 according to the processing content of the semiconductor wafer W,
The semiconductor wafer W can be subjected to a desired plasma process by the adjustment voltage.

Further, the four coils 1 serving as the above-mentioned inducing means are provided.
3A surrounds the application section 11A from all sides, and
A is connected to a high-frequency power supply 13B, and a high-frequency voltage of several hundred KHz to 100 MHz, for example, 13.56 MHz is applied by each high-frequency power supply 13B. Then, for example, each of the high-frequency power supplies 13B rotates counterclockwise from the right coil 13A in FIG.
RF voltage with a phase difference of / 2 (coil 13A on the right)
Each voltage is Vsinωt counterclockwise with reference to
Vsin (ωt + π / 2), Vsin (ωt + π), and Vsin (ωt + 3π / 2)) are applied to the four coils 13A, respectively, to form a high-frequency rotating magnetic field B in the application unit 11A. It is configured as follows. Each of the coils 13A has a role as an antenna for generating an electromagnetic wave or electromagnetic energy for plasma generation by the power supplied from the respective high-frequency power supply 13B.
3 KW is preferred. Therefore, also referred to as antenna optionally <br/> the coil in the following description. In the present embodiment, the coil 13A is a one-turn coil formed by bending one metal wire along the outer surface of the application unit 11A as shown in FIG. These coils 13A are shown in FIGS.
As shown in FIG. 3, the application section 11A is provided via a cylinder 51 (see FIG. 3) formed of, for example, a ferrite-based material.
It is attached to the outer peripheral surface. The cylindrical body 51 has a function of preventing electrostatic coupling with the application unit 11A charged during processing and preventing an electrostatic coupling component of the electromagnetic wave generated from the antenna 13A from entering the application unit 11A. Have. In FIG. 3, the high frequency power supply 13B is a single coil 13
A, but in fact, the other coil 13A is also connected to a high frequency power supply 13B as shown in FIGS. Therefore, there is no possibility that a negative potential is generated on the inner peripheral surface of the application portion 11A by the cylindrical body 51. As a result, there is no sputtering phenomenon on the inner wall of the application portion 11A based on the negative potential, and the material of the inner wall of the application portion 11A is plasma-based. It is possible to prevent contamination due to the material of the inner surface of the processing container 11 without being ejected inside. This cylinder 51
Can be omitted, in which case each coil 13
A may be directly attached to the outer peripheral surface of the application unit 11A, or may be attached at a predetermined interval from the outer peripheral surface of the application unit 11A. Further, each coil 13A is preferably formed as a one-turn coil or a two-turn coil as described above so as not to increase its impedance, but is not necessarily limited to such a shape. In FIGS. 1 to 3, reference numeral 13C denotes a matching circuit.

The application unit 1 is controlled by the coil 13A.
High frequency rotating magnetic field B generated in the plasma generation region in 1A
Extends horizontally, the susceptor 12 and the gas supply unit 1
It is orthogonal to the electric field E formed between 1C. The processing gas is ionized by the electric field E formed from the high-frequency rotating magnetic field B to generate plasma, and the plasma is densified by the high-frequency rotating magnetic field B. Therefore, 0.005 Torr
Even in the following high vacuum, uniform and high-density plasma can be obtained from the processing gas. Since the horizontal high-frequency rotating magnetic field B is used to generate the plasma, the lines of magnetic force do not cross the semiconductor wafer W, and no eddy current occurs in the semiconductor wafer W. Therefore, there is no possibility that the current in the semiconductor wafer W flows out through the susceptor 12, and as a result, there is no possibility that a trouble such as disconnection of the wiring occurs.

Next, the operation of the plasma processing using the above-described plasma processing apparatus will be described. First, the processing container 11
After the semiconductor wafer W is placed horizontally on the susceptor 12 inside the processing container 11 with the surface to be processed facing upward, the inside of the processing vessel 11 is exhausted by the exhaust port 11.
After a high vacuum of, for example, 0.005 Torr or less through F, the processing gas such as an etching gas and a film forming gas is supplied into the processing chamber 11 from the gas supply hole 11E of the gas supply unit 11C while continuing the evacuation. And four more coils 1
A high frequency voltage is applied from 3A. As a result, the application unit 11
In A, a horizontal high-frequency rotating magnetic field B is generated, and plasma of the processing gas is generated. At this time, since the high-frequency voltages of the coils 13A have a phase difference of π / 2 in the counterclockwise direction, the application direction of the high-frequency rotating magnetic field B is also sequentially rotated in the counterclockwise direction and the high-frequency rotating magnetic field B rotates in the application section 11A. the rotating magnetic field B to <br/> form. Then, the plasma is homogenized by the action of the high frequency rotating magnetic field B. The high-density and uniform plasma thus formed is applied to the semiconductor wafer W on the susceptor 12.
, And ions in the plasma are drawn out to the semiconductor wafer W side by the potential difference between the plasma potential and the self-bias potential of the susceptor 12, and a predetermined plasma process is performed on the semiconductor wafer W. At this time, since the gas is continuously supplied from the gas supply unit 11C while the evacuation is continued in the application unit 11A, the processing gas is successively replenished to the plasma to maintain the uniform plasma and to generate the already generated plasma. The plasma is supplied downward to facilitate plasma processing.

As described above, according to the present embodiment, the processing vessel 1 is controlled by the four coils 13A outside the processing vessel 11.
Since the high-frequency rotating magnetic field B is formed in the first application section 11A and the electromagnetic waves are supplied to generate the plasma, the plasma is generated without being restricted by the gap length between the parallel plate electrodes as in the related art. The inside of the processing container 11 can be reduced by about one or two digits, for example, about 0.1 digit.
Plasma can be generated even in a high vacuum of 005 Torr or less, and plasma processing can be performed in accordance with the demand for ultrafine processing. Further, since there is no plasma generation electrode in the processing vessel 11, the processing vessel 11
There is no danger of generating impurities in the semiconductor wafer W, and there is no contamination of the semiconductor wafer W. Moreover, according to the present embodiment, since the plasma is rotating during the processing of the semiconductor wafer W, it is possible to always maintain a uniform plasma, and therefore, it is possible to perform a uniform plasma processing on the entire surface of the semiconductor wafer W. it can. Further, according to the present embodiment, the surfaces of the application section 11A for applying the high frequency rotating magnetic field B and the gas supply section 13C facing the semiconductor wafer W are each formed of an insulating material (dielectric material) such as quartz. The electromagnetic field from the coil 13A at the location is not shielded by the application unit 11A, so that a good high-frequency rotating magnetic field B can be formed in the application unit 11A. A uniform plasma can be maintained without being disturbed. Further, according to the present embodiment, since each coil 13A is provided in the processing container 11 via the cylindrical body 51 which is an electrostatic coupling preventing member, the electrostatic coupling component of the electromagnetic waves from the four coils 13A is processed. The inside of the container 11 is prevented by the cylindrical body 51, thereby preventing charging on the inner surface of the processing container 11, and further preventing a sputtering phenomenon on the inner surface of the processing container 11, resulting from the material on the inner surface of the processing container 11. Contamination of the impurities can be prevented. Furthermore, since the portions other than the application portion 11A of the processing container 11 are formed of a conductive material such as aluminum, it is possible to prevent electrification in these portions and secure safety, and the processability is excellent. Further, in the high-frequency rotating magnetic field B, the lines of magnetic force extend parallel to the surface to be processed of the semiconductor wafer W and do not intersect with the semiconductor wafer W. Therefore, there is no possibility that an eddy current is generated in the semiconductor wafer W. There is no possibility that the current flowing through the susceptor 12 flows out, and as a result, there is no possibility that a trouble such as disconnection of the wiring may occur.

In the above-described embodiment, the induction means constituted by individually connecting the high-frequency power supply 17 to each of the four coils 13A has been described. However, the induction means is separated from each other by 180 ° in the opposite position, that is, in the circumferential direction. A pair of coils 13 in position
A, 13A, and these coils 13A, 13A
May be applied with a high-frequency voltage 180 ° out of phase. In this case, a rotating magnetic field is not generated in the application section 11A, but a magnetic field oscillating in the horizontal direction can be formed to generate plasma similar to the rotating magnetic field. In this case, if each coil 13A is wound in the opposite direction, a common high-frequency power supply can be used.

As shown in FIG. 4, four coils 1
Out of 3A , two coils 13A, 13A face each other
And arranged, these coils 13A, 13A in one of the high frequency power source 13B is connected, connect the other opposing <br/> coils 13A, in one of the high frequency power source 13B similarly applies 13A Π at the same frequency
/ 2 phase difference, and each of the four coils 13A
High-frequency power having a phase difference is sequentially applied, and the high-frequency magnetic field becomes π
A high-frequency rotating magnetic field that rotates by / 2 may be generated. The structure of the guiding means used in the present invention is not particularly limited as long as it can form an electromagnetic field that moves at high speed by rotation or vibration in a plane substantially parallel to the surface to be processed. For example, a high frequency voltage having a phase difference of 2π / 3 may be applied to three coils arranged at 120 ° apart in the circumferential direction, and a high frequency rotating magnetic field may be generated by these coils. Also,
The number of coils may be four or more.

Further, in the above-described embodiment, the vertical processing container has been described. However, the object to be processed such as a semiconductor wafer does not necessarily have to be supported horizontally, for example, a horizontal processing container which supports and processes vertically. May be adopted. Also,
In these processing containers, a plurality of objects may be accommodated and processed simultaneously.

[0029]

As described above, according to the first aspect of the present invention, an object to be processed for processing by the processing gas supplied into the processing container is supported and the processing container is supported. And a gas supply unit provided on a surface facing the support, and a high-frequency voltage is applied in a direction along the object in synchronization with the high-frequency voltage by applying a high-frequency voltage. A plurality of individually independent guiding means for forming a magnetic field and turning the processing gas into plasma are arranged along the outer periphery of the processing vessel, and a high-frequency power is applied by sequentially giving a phase difference to the plurality of guiding means. Since the high-frequency power supply is connected to each of the induction means, when the high-frequency electric power is applied to a plurality of independent induction means, respectively,
With a plasma processing gas by a plurality of guide means, high-frequency magnetic field having a phase difference in the direction along the target surface of the object to be processed is generated by each of the plurality of guide means
A rotating magnetic field is formed to increase the density and homogeneity of the processing gas plasma, and to generate high-density plasma even under high vacuum, which cannot be generated by a parallel plate electrode structure. And a plasma processing apparatus capable of performing the above.

According to the invention described in claim 2 of the present invention, in the invention described in claim 1, the plurality of leads are provided.
Inductive antennas are provided as means ,
A plasma processing apparatus capable of emitting electromagnetic waves from an induction antenna into a processing chamber can be provided.

According to the invention described in claim 3 of the present invention, in the invention described in claim 1 or claim 2,
Each of the plurality of guiding means generates an electromagnetic wave ,
For processing in the processing vessel by electromagnetic waves from multiple guiding means
A plasma processing apparatus capable of converting gas into plasma can be provided.

According to the invention described in claim 4 of the present invention, in the invention described in claim 1 or claim 2,
Since the processing container is formed of a dielectric material at least a part of the wall surface of the processing container disposed opposite to the plurality of guiding means, it is possible to form a stable high-frequency magnetic field in the processing container and further homogenize the plasma. It is possible to provide a plasma processing apparatus excellent in safety and workability.

Further, according to the invention described in claim 5 of the present invention, in the invention described in any one of claims 1 to 3, through the electrostatic coupling preventing member the plurality of guide means As a result, the electrostatic coupling component of the electromagnetic waves from the plurality of inducing means is prevented from entering the processing container by the electrostatic coupling prevention member, thereby preventing charging on the inner surface of the processing container. In addition, it is possible to provide a plasma processing apparatus which can prevent a sputtering phenomenon on the inner surface of the processing container and prevent impurities from being mixed due to a material on the inner surface of the processing container.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the gas supply unit faces the object.
Since it has a plurality of gas supply holes that are evenly distributed on the surface of dielectric materials, to processes for gas electromagnetic wave occurring by the plurality of guide means is replenished from the gas supply holes without disturbance in the plasma generation region Thus, it is possible to provide a plasma processing apparatus that acts uniformly and thereby generates uniform plasma.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a plasma processing apparatus of the present invention.

FIG. 2 is a horizontal sectional view of the plasma processing apparatus shown in FIG.

FIG. 3 is a perspective view showing a plurality of guiding means taken out of the plasma processing apparatus shown in FIG. 1;

FIG. 4 is a diagram corresponding to FIG. 2, showing another embodiment of the plasma processing apparatus of the present invention.

[Explanation of symbols]

 W Semiconductor wafer (object to be processed) B High-frequency electromagnetic field 11 Processing container 11A Applying part 11B Processing part (part other than applying part) 11C Gas supply part (surface facing object to be processed) 11E Gas supply hole 12 Susceptor (support) 13A guide means 51 cylinder (electrostatic coupling prevention member)

Claims (6)

(57) [Claims] 1. A support for supporting an object to be processed by a processing gas supplied into a processing container and provided on a surface opposed to the support provided in the processing container and provided in the processing container. A plurality of independent inductions for forming a high-frequency magnetic field in a direction along the object to be processed in synchronization with the high-frequency voltage by applying the high-frequency voltage and for converting the processing gas into plasma. Means are arranged along the outer periphery of the processing container, and a high-frequency power source for applying a high-frequency power to each of the plurality of inducing means by sequentially providing a phase difference is provided.
A plasma processing apparatus connected to an inducing means . 2. An induction antenna as said plurality of guidance means.
2. The plasma processing apparatus according to claim 1, further comprising: 3. The plurality of guiding means each generate an electromagnetic wave.
The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is generated . 4. The processing container according to claim 1 , wherein at least a part of a wall surface of the processing container disposed opposite to the plurality of guiding means is formed of a dielectric material .
The plasma processing apparatus according to claim 3 . 5. The plasma processing apparatus according to claim 1, wherein the plurality of guiding means are provided in the processing container via an electrostatic coupling preventing member. 6. The gas supply unit faces the object to be processed.
The plasma processing apparatus according to any one of claims 1 to 5, further comprising a plurality of gas supply holes uniformly distributed on a surface made of a dielectric material .