JP2022006424A - Plasma processing apparatus - Google Patents

Abstract

To provide a plasma processing apparatus which has a high non-defective yield by improving the processing uniformity around the outer periphery of a substrate to be processed.SOLUTION: A plasma processing apparatus comprises: a processing chamber in which a sample is plasma-processed; a high-frequency power source which supplies high-frequency microwave power for generating plasma; a magnetic field formation mechanism which forms a magnetic field in the processing chamber; a sample table on which the sample is placed; and a first gas supply plate which supplies first gas into the processing chamber and is disposed above the processing chamber. The plasma processing apparatus further comprises a second gas supply plate which supplies second gas into the processing chamber and is disposed below the first gas supply plate. The first gas supply plate has a plurality of holes formed at the center. The second gas supply plate has a circular opening at the center. The area of the opening is larger than that of a region where the holes are located.SELECTED DRAWING: Figure 1

Description

The present invention relates to a plasma processing apparatus that processes a substrate-like sample such as a semiconductor wafer arranged in the processing chamber by using plasma formed in the processing chamber in the vacuum vessel such as etching.

In the manufacturing process of semiconductor devices, plasma treatment is widely used for applications such as film formation, etching, and ashing. The state-of-the-art semiconductor device is required to process a fine structure at the nm level, and further, good processing uniformity is required to ensure this processing accuracy on the entire surface of the substrate to be processed. In order to ensure good processing uniformity, various parameters such as high-frequency power for plasma generation input to the plasma processing apparatus and the temperature distribution of the substrate stage are adjusted. However, depending on the plasma processing conditions, good processing uniformity may not be ensured on the entire surface of the substrate to be processed even if the input parameters of the device are adjusted.

ECR (Electron Cyclotron Resonance), inductive coupling, capacitive coupling, and the like are known as plasma generation methods in a plasma etching apparatus. The ECR method is a plasma generation method that utilizes a resonance phenomenon in which the rotation frequency of electrons rotating around magnetic lines and the microwave frequency match. By controlling the coil magnetic field used for ECR plasma generation, the ECR plasma generation region can be changed to adjust the ion flux in the surface of the substrate to be processed.

Since the ions generated in the plasma processing apparatus are deactivated on the inner wall of the apparatus in the process of being transported to the substrate to be processed, the ions may be insufficient in the outer peripheral portion of the substrate to be processed and the etching rate may be high at the center. As a means for solving the shortage of ions in the outer peripheral portion, for example, in Patent Document 1, in a device that generates plasma by injecting an electromagnetic wave from the outside of the decompression processing chamber, a radical is generated around the outer periphery of the sample table. It is described that the high frequency power of is input.

Further, Patent Document 2 and Patent Document 3 describe that the second gas is supplied from the outer edge portion to the substrate to be processed inside the plasma processing apparatus.

Japanese Unexamined Patent Publication No. 2013-84653 Japanese Unexamined Patent Publication No. 2018-78010 Japanese Unexamined Patent Publication No. 2008-124190

Since the ions generated in the plasma processing apparatus are deactivated on the inner wall of the apparatus in the process of being transported to the substrate to be processed, the ions may be insufficient in the outer peripheral portion of the substrate to be processed and the etching rate may be high at the center. Patent Document 1 describes supplying radicals to the outer periphery of the sample, but since it is considered that ions are generated at the same time as the radicals, it can be presumed that the method can also supply ions to the outer periphery of the sample. If the method described in Patent Document 1 is used, the insufficient ions can be supplemented on the outer periphery of the sample, so that uniform etching rate distribution at the center height can be expected.

On the other hand, the method described in Patent Document 1 has concerns from the viewpoint of foreign matter and metal contamination that cause a deterioration in yield in mass production of semiconductor devices. In the manufacture of semiconductor devices, if metal particles or fine foreign substances adhere to a sample, the device characteristics are significantly deteriorated. Therefore, it is necessary to suppress the generation of metal particles or fine foreign substances.

Generally, the outer peripheral portion of the sample table of the plasma etching apparatus is covered with a dielectric member in order to protect the sample table from damage caused by ions. When high-frequency power is supplied to the outer peripheral portion of the sample table, there is a risk that an abnormal discharge will occur in the gap between the dielectric member and the sample table due to the electric field of the high-frequency power. At this time, the surface of the sample table may be sputtered by the ions generated by the abnormal discharge, and metal particles or minute foreign substances derived from the materials constituting the sample table may be generated.

Further, in the method of supplying the second gas from the outer edge portion as described in Patent Document 2 and Patent Document 3, the second gas is supplied to the inside of the device without being ionized, so that the device is simply used. Even if the second gas is supplied from the outer edge portion, it cannot be a means for supplying ions to the outer peripheral portion of the substrate to be processed.

The present invention solves the above-mentioned problems of the prior art and makes it possible to control the distribution of ions incident on the wafer, and as compared with the prior art, the uniformity of the treatment in the vicinity of the outer peripheral portion of the substrate to be treated is improved. It is an object of the present invention to provide a plasma processing apparatus capable of performing plasma processing having a high non-defective yield by making it possible to improve the quality.

In order to solve the above-mentioned problems of the prior art, in the present invention, a processing chamber in which the sample is plasma-processed, a high-frequency power source for supplying high-frequency microwave power for generating plasma, and a magnetic field are formed in the processing chamber. In a plasma processing apparatus provided with a magnetic field forming mechanism, a sample table on which a sample is placed, and a first gas supply plate arranged at the upper part of the processing chamber to supply the first gas to the processing chamber, the processing chamber Further provided with a second gas supply plate located below the first gas supply plate to supply the second gas to the first gas supply plate, the first gas supply plate has a plurality of holes formed in the center, and the second The gas supply plate of the above has a circular opening in the center, and the area of the opening is larger than the area of the region where the holes are arranged.

According to the present invention, in the plasma processing apparatus, it has become possible to control the distribution of ion flux near the surface of the substrate to be processed. As a result, the uniformity of the treatment in the vicinity of the outer peripheral portion of the substrate to be treated can be improved as compared with the conventional technique, and it is possible to perform plasma treatment having a high yield of non-defective products.

It is a schematic cross-sectional view which shows the schematic structure of the whole of the plasma processing apparatus which concerns on 1st Embodiment. It is a perspective view of the shower plate which concerns on 1st Embodiment. It is a perspective view of the gas supply plate which concerns on 1st Embodiment. It is a graph which shows (a) the cross-sectional view of the apparatus which concerns on the 1st Example, and (b) the ion flux distribution on the substrate to be processed when the Ar flow rate of the 2nd gas is low. It is a graph which shows (a) the cross-sectional view of the apparatus which concerns on the 1st Example, and (b) the ion flux distribution on the substrate to be processed when the Ar flow rate of the 2nd gas is high. It is a graph which shows the ion flux distribution shape change by the time ratio of a step A and a step B. Enlarged cross-sectional view of the outer circumference of the microwave introduction window, shower plate, and gas supply plate It is a top view from the bottom of the microwave introduction window which concerns on 1st Example. It is a top view of the gas supply plate which concerns on 1st Embodiment. It is a schematic cross-sectional view which shows the schematic structure of the whole of the plasma processing apparatus which concerns on 2nd Embodiment. It is a graph which shows (a) the cross-sectional view of the apparatus which concerns on the 2nd Example, and (b) the ion flux distribution on the substrate to be processed when Ar is supplied as a 2nd gas. It is a graph which shows (a) the cross-sectional view of the apparatus which concerns on the 2nd Example, and (b) the ion flux distribution on the substrate to be processed when Ar is supplied as a 3rd gas. It is a schematic cross-sectional view which shows the schematic structure of the whole of the plasma processing apparatus which concerns on 3rd Embodiment. It is a schematic cross-sectional view which shows the schematic structure of the whole of the plasma processing apparatus which concerns on 4th Embodiment.

The present invention includes a processing chamber in which a sample is treated with plasma, a high-frequency power source for supplying microwaves for generating plasma, a magnetic field forming mechanism for forming a magnetic field in the processing chamber, and a sample table on which the sample is placed. , The first gas in the plasma processing apparatus provided with the first gas supply plate which supplies the first gas to the processing chamber and is arranged in the upper part of the processing chamber and has at least one hole formed in the center thereof. A second gas supply plate located below the supply plate and having an opening in the center is further provided, and the second gas is supplied to the processing chamber through between the first gas supply plate and the second gas supply plate. It is characterized by having such a configuration.

Further, in the present invention, the means for adjusting the ion flux on the outer peripheral portion of the substrate to be processed and making the etching rate uniform by using the above-mentioned apparatus mainly uses Ar as the second gas in the etching treatment using the apparatus. The etching rate by a series of plasma treatments includes at least one first step of supplying a gas as a component and at least one second step of supplying a gas not containing Ar as a main component as a second gas. It is characterized in that the time ratio between the first step and the second step is adjusted so that the temperature becomes uniform in the radial direction.

Further, the present invention has a plasma processing chamber provided with a substrate electrode on which a substrate to be processed is placed, a vacuum chamber provided with a cavity, and a dielectric window for separating the plasma processing chamber and the cavity, and microwaves. In a plasma processing apparatus equipped with a microwave power supply unit that propagates power to a cavity of a vacuum chamber and a magnetic field forming unit that forms a magnetic field inside the vacuum chamber, the vacuum chamber has a large number of small holes in the center. A second gas introduction portion between a shower plate having a formed region and having a first gas introduction portion formed between the dielectric window and a shower plate having an opening in the center. The diameter of the opening of the gas introduction plate is larger than the diameter of the central region where many small holes of the shower plate are formed, and the diameter of the opening of the gas introduction plate is larger than the outer diameter of the substrate to be treated. The present invention relates to a plasma processing apparatus which is formed small to improve the uniformity of processing in the vicinity of the outer peripheral portion of the substrate to be processed so that the yield of non-defective products is higher than that of the conventional one.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the present embodiment, those having the same function shall be designated by the same reference numerals, and the repeated description thereof will be omitted in principle.

However, the present invention is not limited to the description of the embodiments shown below. It is easily understood by those skilled in the art that a specific configuration thereof can be changed without departing from the idea or purpose of the present invention.

A cross-sectional view of FIG. 1 shows a schematic configuration of a plasma processing apparatus 100 that performs an etching process using microwave power according to the first embodiment of the present invention.

In the plasma processing apparatus 100 shown in FIG. 1, 50 is a vacuum chamber, which is composed of a lower vacuum chamber 51, an intermediate vacuum chamber 52, and an upper vacuum chamber 53. A headpiece 30 is sandwiched between the intermediate vacuum chamber 52 and the upper vacuum chamber 53. A plasma processing chamber 9 is formed inside the lower vacuum chamber 51.

Microwaves are oscillated from the microwave source 1 in the plasma processing apparatus 100 shown in FIG. 1, and the circular waveguide 5 is passed through the isolator 2, the automatic matching device 3, the rectangular waveguide 4, and the circular rectangular converter 4-1. Is transmitted to. In this embodiment, microwaves of 2.45 GHz, which are often used industrially, are used.

The isolator 2 is used to protect the microwave source 1 from the reflected wave, and the automatic matcher 3 is used to adjust the load impedance, suppress the reflected wave, and efficiently supply the electromagnetic wave. The microwave introduced from the circular waveguide 5 propagates in the cavity 6 inside the upper vacuum chamber 53, passes through the microwave introduction window 7 and the shower plate 8, and is introduced into the plasma processing chamber 9.

An electromagnetic coil 10 is provided around the plasma processing chamber 9, and a yoke 11 is provided on the outer periphery thereof. By supplying a current to the electromagnetic coil 10, the static magnetic field distribution is adjusted in the plasma processing chamber 9 so as to satisfy the magnetic flux density required for ECR. The yoke 11 has a role of a magnetic shield that prevents the leakage of the magnetic field to the outside of the device. For 2.45 GHz microwaves, the magnetic flux density required for ECR is 875 G. By adjusting the static magnetic field distribution so that the isomagnetic field surface (ECR surface) of 875G enters the plasma processing chamber 9, the plasma 12 is efficiently generated.

An inner cylinder 13 is installed on the inner side wall of the intermediate vacuum chamber 52 facing the plasma processing chamber 9 in order to protect it from the plasma 12 generated inside the plasma processing chamber 9. Quartz is used as a material having high plasma resistance for the inner cylinder 13 located in the vicinity of the plasma 12. Alternatively, as a material having high plasma resistance, yttrium, alumina, yttrium fluoride, aluminum fluoride, aluminum nitride and the like may be used.

A microwave introduction window 7, a shower plate 8, and a gas supply plate 14 are installed above the plasma processing chamber 9. The outer peripheral portions of the microwave introduction window 7, the shower plate 8, and the gas supply plate 14 are supported by the headpiece 30. The detailed structure around the headpiece 30 will be described later. As the material of the microwave introduction window 7, the shower plate 8 and the gas supply plate 14, quartz is used as the material for transmitting microwaves. Alternatively, another dielectric material may be used as long as it is a material that transmits microwaves. Alternatively, as a material having high plasma resistance, yttrium, alumina, yttrium fluoride, aluminum fluoride, aluminum nitride and the like may be used.

The first gas is supplied from the first gas supply means 15 between the microwave introduction window 7 and the shower plate 8 in a state where the flow rate is adjusted. A plurality of gas holes 26 are provided in the central region 81 of the shower plate 8, and the first gas is supplied to the plasma processing chamber 9 through the gas holes 26.

A second gas is supplied from the second gas supply means 16 between the shower plate 8 and the gas supply plate 14 in a state where the flow rate is adjusted. An opening 141 is formed in the center of the gas supply plate 14, and the second gas supplied from the second gas supply means 16 passes between the shower plate 8 and the gas supply plate 14 and passes through the gas supply plate 14. It is supplied to the plasma processing chamber 9 from the opening 141 of 14.

The first gas supply means 15 and the second gas supply means 16 are respectively provided with a mass flow controller, and the mass flow controller brings the first gas and the second gas of a desired flow rate to the plasma processing chamber 9. Includes the ability to supply.

Further, the gas type to be used is appropriately selected according to the film to be treated and the like formed on the substrate 19 to be treated, and a plurality of gas types are combined and supplied at a predetermined flow rate. The supplied gas is evacuated by the turbo molecular pump 18 via the conductance adjusting valve 17. The opening degree of the conductance adjusting valve 17 is adjusted so that the pressure inside the plasma processing chamber 9 becomes a predetermined pressure. As the pressure in the plasma processing chamber 9, a pressure of about 0.1 Pa to several Pa is used.

A substrate stage / high frequency electrode 20 (hereinafter referred to as a substrate electrode 20) on which the substrate 19 to be processed is placed is provided in the lower part of the plasma processing chamber 9, and an insulating plate 21 is provided in the lower part thereof. A bias power supply 23 for supplying bias power for drawing ions into the substrate 19 to be processed is connected to the substrate electrode 20 via an automatic matching unit 22.

In this embodiment, the frequency of the bias power supply 23 is 400 kHz. The substrate electrode 20 is provided with an adsorption mechanism and temperature control means for the substrate to be processed (not shown), and the temperature of the substrate to be processed is adjusted as necessary so that desired etching can be performed. A susceptor 24 and a stage cover 25 are installed to protect the outer peripheral portion of the substrate electrode 20 from the plasma 12. Quartz is used as a material having high plasma resistance for the susceptor 24 and the stage cover 25.

In the etching, the magnetic field formed by the electromagnetic coil 10 and the first gas and the second gas introduced into the plasma processing chamber 9 by the microwave supplied from the microwave source 1 are converted into plasma, and the ions and radicals generated there are converted into plasma. It is done by irradiating the substrate 19 to be processed.

FIG. 2A shows a perspective view of the shower plate 8, and FIG. 2B shows a perspective view of the gas supply plate 14. In the shower plate 8, a large number of gas holes 26 for introducing gas into the plasma processing chamber 9 are arranged in a region 81 within the diameter D1 of the central portion. The space inside the gas hole 26 needs to be sufficiently narrowed so that an electric discharge is not generated inside the gas hole 26 when the microwave is introduced from the microwave source 1. In this embodiment, the inner diameter of the gas hole 26 is 0.8 mm or less. An opening 141 having a diameter of D2 is formed in the center of the gas supply plate 14.

Assuming that the diameter of the substrate 19 to be processed is D, the relationship between D, D1 and D2 is set to be as shown in (Equation 1).

This relationship can be understood from the effects of this embodiment described later.

As an effect of this embodiment, a method of increasing the ion flux on the outer peripheral portion of the substrate 19 to be processed and a means for making the ion flux distribution uniform in the surface of the substrate 19 to be processed will be described.

First, a method of increasing the ion flux on the outer peripheral portion of the substrate 19 to be processed will be described. 3A and 3B are diagrams illustrating the outline of the effect of the present invention.

In the upper part (a) of FIG. 3A, the process gas required for plasma treatment of the substrate 19 to be processed is supplied as the first gas from the first gas supply means 15, and the second gas is supplied from the second gas supply means 16. An enlarged cross-sectional view of the plasma processing chamber 9 is shown when a small amount or no Ar is supplied. In this embodiment, Ar is supplied in an amount of 50 sccm. At this time, the plasma 12 is formed in the plasma processing chamber 9.

The lower part (b) of FIG. 3A shows the radial distribution of the ion flux on the substrate 19 to be processed at that time. The ion flux distribution on the substrate 19 to be processed is the distribution of the center height. The ion flux distribution at the center height is that the ions generated from the plasma 12 disappear on the inner wall of the plasma processing chamber 9 in the process of transporting the ions to the substrate 19 to be processed, or the generation distribution of the plasma 12 is in the central part of the plasma processing chamber 9. It is a commonly seen distribution shape, such as when it is high.

The upper part (a) of FIG. 3B shows an enlarged cross-sectional view of the plasma processing chamber 9 when a large flow rate of Ar is supplied as the second gas from the second gas supply means 16. The lower part (b) of FIG. 3B shows the radial distribution of the ion flux on the substrate 19 to be processed. In this embodiment, Ar is supplied in an amount of 300 sccm. When a large flow rate of Ar is supplied as the second gas, the second plasma 27 is formed in the vicinity of the inner peripheral surface of the gas supply plate 14 and the lower surface of the shower plate 8.

Next, the mechanism by which the second plasma 27 is formed will be described. Ar is known to generate long-lived metastable excited atoms with an energy of 11.6 eV. Since the ionization energy of Ar is 15.8 eV, it is ionized if the metastable excited atom of Ar is given an energy of about 4.2 eV. In other words, the presence of metastable excited atoms facilitates ionization, so Ar tends to generate and maintain high-density plasma. Therefore, the second plasma 27 is generated and maintained on the inner peripheral surface of the gas supply plate 14 and the lower surface of the shower plate 8 where the gas density of Ar is locally increased.

For the generation of the second plasma 27, it is desirable that the first gas and the second gas do not mix on the inner peripheral surface of the gas supply plate 14 and the lower surface of the shower plate 8. If mixed, the energy of the metastable excited atom of Ar is also used for the dissociation of the first gas and the like, which hinders the efficient generation of the second plasma 27.

Here, as a condition that the first gas and the second gas do not mix on the inner peripheral surface of the gas supply plate 14 and the lower surface of the shower plate 8, a large number of gas holes 26 arranged in the center of the shower plate 8 have diameters D1. It is necessary to satisfy D1 <D2 with the diameter D2 of the opening at the center of the gas supply plate 14. Further, even if the first gas flows back into the gap between the lower surface of the shower plate 8 through which the second gas passes and the upper surface of the gas supply plate 14, the efficient generation of the second plasma 27 is hindered, so that the first gas is introduced. It is necessary to narrow the gap sufficiently so that it does not diffuse into the gap. In this embodiment, the distance between the lower surface of the shower plate 8 and the upper surface of the gas supply plate 14 is 0.3 mm.

Further, even when the Ar flow rate supplied as the second gas is small, the first gas may flow back into the gap between the lower surface of the shower plate 8 and the upper surface of the gas supply plate 14. Therefore, in order to generate the second plasma 27, it is necessary to increase the Ar flow rate of the second gas.

In this embodiment, Ar is used as the second gas as the gas for forming the metastable excited atom, but a rare gas such as He may be used as the gas for forming the metastable excited atom. Further, in this embodiment, Ar is used as a single gas as the second gas, but it may be paraphrased as a gas containing Ar as a main component.

Alternatively, so-called Penning ionization may be used in which a gas that is ionized at an energy lower than the energy of the metastable excited atom of the supply gas is mixed to promote ionization. If Penning ionization is used, the discharge start voltage is greatly reduced, so that the generation and maintenance of the second plasma 27 becomes easy. For example, a mixed gas of Ne and Ar, which is well known as a gas system in which Penning ionization occurs, may be used as the second gas.

In the upper part (a) of FIG. 3B, only the magnetic field lines 150 passing through the second plasma 27 are extracted and described. Normally, in the generation of plasma using ECR, a magnetic field (diffusion magnetic field) that spreads divergently from the upper side to the lower side of the device is used. The main reason why the diffused magnetic field is used is that there is no cutoff when the clockwise circular polarization (R wave) of the microwave that contributes to the generation of ECR plasma is incident from the strong magnetic field side to the low magnetic field side, and plasma processing is performed. This is because it can propagate to the ECR surface in the chamber 9 and efficiently generate plasma. The charged particles wind around the lines of magnetic force, and as a result of suppressing the diffusion of the charged particles in the direction perpendicular to the lines of magnetic force, the charged particles are easily transported in the direction along the lines of magnetic force. That is, the ions generated by the second plasma 27 are mainly transported along the magnetic field lines 150.

With the shape of the magnetic field line 150 shown in FIG. 3B (a), the ions generated by the second plasma 27 are transported along the magnetic field line 150 to the outer peripheral portion of the substrate 19 to be processed, and are transported to the lower portion (b) of FIG. 3B. As shown, the ion flux distribution shape is the outer peripheral height.

In order to efficiently transport the ions from the second plasma 27 to the outer periphery of the substrate 19 to be processed, it is desirable that the magnetic field lines 150 passing through the second plasma 27 pass through the outer periphery of the substrate 19 to be processed. .. Further, considering that the magnetic field lines have a divergent shape from the upper side to the lower side of the device, it is necessary to satisfy D2 <D.

Further, since the diffusion coefficient of the charged particles in the direction perpendicular to the magnetic field lines is not zero, even if the magnetic force lines 150 passing through the second plasma 27 extend to the outer peripheral side of the substrate 19 to be processed such as the susceptor 24, the second The ions generated by the plasma 27 of the above reach the outer peripheral portion of the substrate 19 to be processed. As a matter of course, the farther the magnetic field lines passing through the second plasma 27 are from the outer peripheral portion of the substrate 19 to be processed, the more difficult it is for the ions generated by the second plasma 27 to reach the outer peripheral portion of the substrate 19 to be processed. In other words, the amount of increase in ion flux on the outer peripheral portion of the substrate 19 to be processed can be adjusted by adjusting the current of the electromagnetic coil 10 to change the shape of the magnetic field lines. That is, the ion flux distribution at the center height can be made uniform.

Next, another method of making the ion flux distribution averaged over a series of plasma processing times uniform by this apparatus will be described. When the substrate 19 to be treated is plasma-treated, when a small amount of Ar is supplied or not supplied as the second gas as shown in FIG. 3A, a large amount of Ar is used as the second gas as shown in Step A and FIG. 3B. Let the case where the flow rate is supplied be referred to as step B, and consider the case where a series of plasma processes are configured by combining these steps.

When ion flux with a center height is obtained in step A and an ion flux with an outer circumference height is obtained in step B, the time-averaged ion flux distribution shape is adjusted and made uniform by adjusting the time ratio between step A and step B constituting the plasma treatment. can. As shown in FIG. 3A (b), the ion flux 301 having the central portion a and the outer peripheral portion b in step A, and the central portion c and the outer peripheral portion d in step B as shown in FIG. 3B (b). Consider the case where the ion flux 302 is obtained.

For the sake of simplicity, as a guideline for time-averaged ion flux homogenization, considering the condition that the time-averaged ion flux is equal in the central portion and the outer peripheral portion of the substrate 19 to be processed, steps A and B are given as a guideline for homogenization. The relationship is as shown in (Equation 2) as the optimum time ratio (tB / tA) of.

tA and tB are the processing times of step A and step B, respectively.

FIG. 4 shows a schematic diagram of the time-averaged ion flux distribution when the time ratio between step A and step B is changed. The time-averaged ion flux distribution is a uniform ion flux 410 when tB / tA = α, an ion flux 411 with an outer peripheral height distribution when tB / tA> α, and a center height when tB / tA <α. The distributed ion flux is 412. The actual distribution shape is the curvature of the curve, such as the U-shape or V-shape of the alphabet U-shape even if the distribution shape is the outer circumference height, and the inverted U-shape or the inverted V-shape even if the distribution shape is the center height. Including, there are various things, and (Equation 2) only gives a guideline for homogenization.

Further, in many cases, an M-shaped distribution or a W-shaped distribution can be obtained. In such a case, a highly uniform ion flux may not be obtained only by adjusting the time ratio of tB / tA. Therefore, in order to obtain a highly uniform ion flux in actual plasma treatment, as shown in this embodiment, in addition to adjusting the time ratio of tB / tA, input parameters to the device such as microwave power are also included. Need to be optimized.

The specific configuration of the outer peripheral portion of the microwave introduction window 7, the shower plate 8, and the gas supply plate 14 in the first embodiment will be described.

FIG. 5 is an enlarged cross-sectional view of the outer peripheral portion of the microwave introduction window 7, the shower plate 8, and the gas supply plate 14. O-rings 31-1 to 31-3 are installed on the headpiece 30, and each O-ring is in close contact with the stepped portion 32 of the microwave introduction window 7, the outer peripheral portion of the shower plate 8, and the stepped portion 34 of the gas supply plate 14. .. Inside the headpiece 30, channels 37 and 38 for passing the first gas from the first gas supply means 15 and the second gas from the second gas supply means 16 are provided. In order to supply gas uniformly in the circumferential direction, a plurality of the gas flow paths may be provided in the circumferential direction.

The microwave introduction window 7 is pressed downward by the atmospheric pressure and its own weight, and the stepped portion 32 on the outer peripheral portion of the microwave introduction window 7 is in close contact with the O-ring 31-1 to ensure the sealing property with the atmosphere. The step portion 33 inside the microwave introduction window 7 is in close contact with the shower plate 8 and presses the shower plate 8 downward. A gap portion 71 is formed between the inside of the step portion 33 and the shower plate 8, and forms a first gas flow path.

When the O-ring 31-2 directly under the shower plate 8 is in close contact with the shower plate 8, the first gas and the second gas supply means 16 supplied from the first gas supply means 15 through the flow path 37 The second gas supplied through the flow path 38 is separated. A step portion 34 is formed around the upper surface of the shower plate 8, and a gap portion 142 is formed between the inside of the step portion 34 and the shower plate 8 to form a second gas flow path. is doing. The O-ring 31-3 at the bottom of the gas supply plate 14 suppresses the second gas from leaking from between the gas supply plate 14 and the headpiece 30 into the plasma processing chamber 9.

FIG. 6A shows a plan view of the microwave introduction window 7 as viewed from below. The step portion 33 inside the microwave introduction window 7 is intermittent in the circumferential direction. Therefore, the first gas is introduced into the gap portion 71 inside the step portion 33 through the portion of the step portion 33 where there is no step, and can flow to the region of the gas hole 26 in the center of the shower plate 8. ..

FIG. 6B shows a plan view of the gas supply plate 14 as viewed from above. The step portion 34 of the gas supply plate is also intermittently arranged in the circumferential direction, and the second gas also passes through the step portion 36 where there is no step, and the gap portion 142 inside the step portion 34 and the shower plate. It is supplied to the inside of the plasma processing chamber 9 from the opening 141 formed in the gas supply plate 14 through the gap with 8.

As described above, in the present embodiment, the plasma processing chamber, the cavity portion, the plasma processing chamber, and the cavity portion, which are provided with a substrate electrode inside and plasma-treat the substrate to be processed placed on the substrate electrode, are separated. A vacuum chamber equipped with a dielectric window made of a dielectric member and capable of exhausting the inside of the plasma processing chamber to a vacuum, and a microwave source and a circular waveguide, the microwave power oscillated from the microwave source is circular. In a plasma processing apparatus provided with a microwave power supply unit propagating to a cavity of a vacuum chamber via a waveguide and a magnetic field forming unit arranged on the outer periphery of the vacuum chamber and forming a magnetic field inside the vacuum chamber. The vacuum chamber is a first type which is located on the side of the dielectric window inside the plasma processing chamber and has a large number of small holes formed in the region of the first diameter in the central portion and is formed between the vacuum chamber and the dielectric window. A shower plate with a first gas inlet leading to a region of the first diameter with a large number of small holes formed through the gap, and a second in the center on the side of the shower plate inside the plasma processing chamber. Further with the first gas supply plate in which an opening having a diameter of 2 is formed and a second gas introduction portion is formed which leads to the opening through a second gap formed between the opening and the shower plate. The second diameter of the opening formed in the first gas supply plate is larger than the first diameter of the central region where many small holes of the shower plate are formed, and is placed on the substrate electrode. It was formed smaller than the outer diameter of the substrate to be treated by plasma treatment.

According to this embodiment, a second gas flows from the opening 141 of the gas supply plate 14 around the first gas supplied to the plasma processing chamber 9 from a large number of gas holes 26 formed in the shower plate 8. By adjusting and supplying the gas, it becomes possible to adjust the distribution of the ion flux on the upper surface of the substrate 19 to be processed placed on the substrate electrode 20, and the substrate 19 to be processed can be uniformly distributed in the plane. It has become possible to perform plasma processing.

Further, by making it possible to supply the second gas from the opening 141 of the gas supply plate 14 by adjusting the flow rate, the substrate 19 to be processed placed on the substrate electrode 20 has a desired distribution in the plane. It has become possible to hold it and perform etching processing.

Further, according to the plasma processing apparatus of this embodiment, it is possible to improve the uniformity of processing in the vicinity of the outer peripheral portion of the substrate to be processed as compared with the conventional technique, and it is possible to perform plasma processing having a high non-defective yield. I made it.

According to this embodiment, it is possible to suppress the risk of adhesion of metal particles and minute foreign substances to the sample, adjust the radial distribution of the ion flux in the surface of the substrate to be treated, and make the etching rate uniform. It will be possible.

When the ion flux distribution shape is W-shaped in the plasma treatment, it is necessary to adjust and homogenize the ion flux at a position between the center and the outer periphery of the substrate 19 to be treated. In the second embodiment, not only the outer periphery of the substrate 19 to be processed but also the ion flux at a position between the center and the outer periphery of the substrate 19 to be processed is adjusted, and the ion flux has a radial resolution of the substrate 19 to be processed. The configuration of the device that can adjust the distribution will be described.

FIG. 7 is an enlarged cross-sectional view of the plasma processing apparatus 200 according to the second embodiment. The basic device configuration is the same as that of the first embodiment. In this embodiment, a second gas supply plate 28 having an opening 281 having a diameter of D3 is installed under the gas supply plate 14, and the third gas supplied from the third gas supply means 29 is supplied. The plasma processing chamber 9 is supplied from the opening 281 through a gap 282 formed between the gas supply plate 14 and the second gas supply plate 28. A gap portion 282 is formed between the second gas supply plate 28 and the gas supply plate 14, and a third gas flow path is formed. The configuration thereof is described with reference to FIGS. 5 and 6B. Since it is the same, the description thereof will be omitted.

In order to be able to adjust the ion flux distribution with radial resolution, the diameter D1 of the region 81 where the gas hole 26 of the shower plate 8 is arranged and the diameter D2 of the opening 141 of the gas supply plate 14 are the first. It is desirable that the relationship between the diameter D3 of the opening 281 of the second gas supply plate 28 and the diameter D of the substrate 19 to be processed satisfies (Equation 3).

As described in Example 1, in the case of a diffused magnetic field, it is necessary to have a relationship of D3 <D in order to efficiently transport the ions generated by the second plasma 27 to the outer peripheral portion of the substrate 19 to be processed. be. Further, as shown in Example 1, the relationship D1 <D2 can be obtained as a condition that the first gas and the second gas do not mix on the gap portion 142 of the gas supply plate 14 and the lower surface of the shower plate 8. The relationship between D2 and D3 will be described by the effect of this embodiment described later.

The effects of the apparatus according to the second embodiment will be described with reference to FIGS. 8A and 8B.
In the upper part (a) of FIG. 8A, the process gas necessary for plasma-treating the substrate 19 to be processed is supplied as the first gas supplied from the first gas supply means 15, and the second gas supply means 16 It shows a state in which Ar is supplied in a large flow rate as the second gas, and Ar is supplied from the third gas supply means 29 as a third gas in a smaller amount or not as compared with the second gas supply means 16.

In this state, a current is supplied to the electromagnetic coil 10 to form a magnetic field, and the microwave power is supplied from the microwave source 1, so that plasma 12 is generated inside the plasma processing chamber 9 and the opening of the gas supply plate 14 is opened. The Ar density increases near the inner peripheral surface of 141 and the lower surface of the shower plate 8, and a second plasma 27 is formed.

The lower part (b) of FIG. 8A shows the radial distribution of the ion flux 801 on the substrate 19 to be processed at that time. As a result of the ions generated by the second plasma 27 being transported along the magnetic field lines 150 passing through the second plasma 27, the effect of increasing the ion flux 801 at the intermediate position between the central portion and the outer peripheral portion of the substrate 19 to be processed. Is obtained. At this time, it is necessary to satisfy the relationship of D2 <D3.

If D2> D3, the ions generated by the second plasma 27 do not reach the substrate 19 to be processed because the second gas supply plate 28 exists on the magnetic field line 150 passing through the second plasma 27. The second gas supply plate 28 disappears and the desired effect cannot be obtained.

In the upper part (a) of FIG. 8B, a small amount or no Ar is supplied as the second gas supplied from the opening 141 to the inside of the plasma processing chamber 9 through the space between the shower plate 8 and the gas supply plate 14. It represents a state when a large flow rate of Ar is supplied as a third gas to be supplied to the inside of the plasma processing chamber 9 from the opening 281 through between the gas supply plate 14 and the second gas supply plate 28.

In this state, by supplying a current to the electromagnetic coil 10 to form a magnetic field and supplying microwave power from the microwave source 1, plasma 12 is generated inside the plasma processing chamber 9 and the Ar density is increased. A second plasma 27-1 is generated in the vicinity of the inner peripheral surface of the opening 281 of the gas supply plate 28 and the lower surface of the gas supply plate 14. At this time, since the second plasma 27-1 is generated on the outer peripheral side of the second plasma 27 in FIG. 8A, as shown in the lower part (b) of FIG. 8B, the ion flux 802 on the outer peripheral portion of the substrate 19 to be processed Will increase.

From the above, the generation position of the second plasma can be changed by adjusting the Ar flow rate supplied as the second gas and the third gas, and the resolution in the radial direction can be obtained in the 19 planes of the substrate to be processed. The amount of increase in ion flux can be adjusted. In this embodiment, the case where the number of gas supply plates is two is shown, but the number of gas supply means and the number of gas supply plates may be increased in order to further improve the radial resolution of the ion flux in the same way.

As described above, in the present embodiment, in the present embodiment, the plasma processing chamber, the cavity portion, the plasma processing chamber, and the cavity portion for plasma-treating the substrate to be processed placed on the substrate electrode with the substrate electrode inside are separated. A vacuum chamber equipped with a dielectric window made of a dielectric member and capable of exhausting the inside of the plasma processing chamber to a vacuum, and a microwave source and a circular waveguide, the microwave power oscillated from the microwave source is circular. In a plasma processing apparatus provided with a microwave power supply unit propagating to a cavity of a vacuum chamber via a waveguide and a magnetic field forming unit arranged on the outer periphery of the vacuum chamber and forming a magnetic field inside the vacuum chamber. The vacuum chamber is a first type formed inside the plasma processing chamber on the side of the dielectric window, in which a large number of small holes are formed in the region of the first diameter in the central portion and formed between the vacuum chamber and the dielectric window. A shower plate with a first gas inlet leading to a region of the first diameter with a large number of small holes formed through the gap, and a second in the center on the side of the shower plate inside the plasma processing chamber. A first opening having a diameter of 2 is formed and a second gas introduction portion is formed leading to the first opening through a second gap formed between the plasma plate and the plasma plate. A second opening having a third diameter is formed in the center on the side of the first gas supply plate inside the plasma processing chamber and is formed between the gas supply plate and the first gas supply plate. A first gas supply plate formed in the first gas supply plate, further comprising a second gas supply plate in which a third gas introduction portion leading to the second opening through the formed third gap is formed. The second diameter of the opening is larger than the first diameter of the central region where the numerous small holes of the shower plate are formed, and the second of the second opening formed in the second gas supply plate. The diameter of 3 was formed to be larger than the second diameter of the first opening formed in the first gas supply plate and smaller than the outer diameter of the substrate to be plasma-treated by placing it on the substrate electrode. ..

According to this embodiment, the openings 141 of the gas supply plate 14 and the openings of the second gas supply plate 28 are around the first gas supplied from the large number of gas holes 26 of the shower plate 8 to the plasma processing chamber 9. By adjusting the switching time from the unit 281 so that the second gas and the third gas can be supplied, the distribution of the ion flux on the substrate electrode 20 is adjusted to be a desired distribution. Therefore, the substrate 19 to be processed placed on the substrate electrode 20 can be uniformly plasma-treated in the plane.

Further, in the present embodiment, the opening 141 of the gas supply plate 14 is provided with respect to the state where the first gas is supplied to the plasma processing chamber 9 at a constant flow rate from a large number of gas holes 26 formed in the shower plate 8. The flow rate and time of the second gas supplied from the plasma processing chamber 9 to the side of the plasma processing chamber 9, and the flow rate and time of the third gas supplied from the opening 281 of the second gas supply plate 28 to the side of the plasma processing chamber 9. By adjusting the above, the distribution of the ion flux on the substrate electrode 20 can be adjusted to a desired distribution, and the substrate 19 to be processed can be uniformly etched.

Further, according to the plasma processing apparatus of this embodiment, it is possible to improve the uniformity of processing in the vicinity of the outer peripheral portion of the substrate to be processed as compared with the conventional technique, and it is possible to perform plasma processing having a high non-defective yield. I made it.

As a third embodiment, a method for facilitating the discharge maintenance of the second plasma 27 will be described. FIG. 9 shows an overall schematic view of the plasma processing apparatus 300 according to the third embodiment. The configuration of the plasma processing apparatus 300 according to the present embodiment is basically the same as that of the first embodiment, but is smaller than the diameter D2 of the opening 141 of the gas supply plate 14 on the lower surface of the shower plate 8. The difference is that the protrusion 83 is formed in the region having the diameter D4. The lower surface of the protrusion 83 is located on substantially the same surface as the lower surface of the gas supply plate 14. The gas hole 26 is formed so as to penetrate the protrusion 83.

In the configuration as shown in FIG. 9, when a large flow rate of Ar is supplied as the second gas from the second gas supply means 16, the second plasma 27-2 is connected to the outer peripheral wall of the protrusion 83 of the shower plate 8. It is surrounded by three sides of the lower surface of the shower plate 8 and the inner peripheral surface of the opening 141 of the gas supply plate 14. Due to the effect that the second plasma 27-2 is confined by being surrounded by a wall surface on three sides, it becomes easy to maintain the discharge. Therefore, as compared with the first embodiment, when a large flow rate of Ar is supplied as the second gas, the effect of increasing the ion flux in the outer peripheral portion of the substrate 19 to be processed can be easily obtained.

According to this embodiment, in addition to the same effect as described in the first embodiment, the ion flux generated on the outer peripheral portion of the substrate 19 to be processed suppresses the diffusion of ions in the plasma 12, so that the substrate to be processed The plasma density above 19 can be increased, and the plasma processing speed can be increased.

In the first embodiment, the flow rate of the second gas supplied from the opening 141 of the gas supply plate 14 to the plasma processing chamber 9 was controlled to be a preset flow rate, but in the present embodiment, the etching process is being performed. The light emission state of the plasma 12 generated in the plasma processing chamber 9 was monitored, and the flow rate of the second gas supplied from the second gas supply means 16 was controlled.

FIG. 10 is a front sectional view showing a schematic configuration of the plasma processing apparatus 400 according to the present embodiment. In FIG. 10, the same parts as those described with reference to FIG. 1 in the first embodiment are assigned the same part numbers to avoid duplicate explanations.

The configuration of the plasma processing apparatus 400 shown in FIG. 10 differs from the configuration of the plasma processing apparatus 100 described with reference to FIG. 1 in the first embodiment by attaching a light emission detector 101 to the circular rectangular converter 4-1 for plasma processing. A spectroscope 102 that detects the light emission of the plasma 12 generated in the chamber 9 and processes the signal detected by the light emission detector 101 is further provided.

The emission spectrum component of the plasma 12 that emits light in the plasma processing chamber 9 changes as the etching of the substrate 19 to be processed progresses. By analyzing the emission detection signal of the plasma detected by the emission detector 101 with the spectroscope 102, the change in the emission spectrum of the plasma 12 is extracted, and the emission spectrum stored in advance by the control unit (not shown). The distribution of the ion flux on the substrate 19 to be processed is adjusted by controlling the flow rate of the second gas supplied from the second gas supply means 16 based on the relationship between the and the etching state of the substrate 19 to be processed. , The substrate 19 to be processed can be uniformly etched.

Further, being able to monitor the light emitted from the plasma processing chamber 9 is also useful for monitoring the state of the apparatus and detecting the end point of the plasma processing. Further, by monitoring the light emission from the plasma 12, it is possible to detect a sign of a malfunction of the plasma processing device 400 from the time course of the light emission intensity and the like. Alternatively, by monitoring the interference light from the substrate 19 to be processed during plasma processing, the film thickness of the film to be processed on the surface of the substrate 19 to be processed can be predicted in real time, and a predetermined film thickness can be etched as much as necessary by plasma processing. The end point can be determined.

Further, by combining with the plasma processing apparatus 200 described in the second embodiment, the second gas and the second gas supply plate 28 supplied from the opening 141 of the gas supply plate 14 according to the change in the emission spectrum of the plasma. By adjusting the supply time and flow rate of the third gas from the opening 281 to adjust the distribution of the ion flux on the substrate 19 to be processed, the substrate 19 to be processed is uniformly etched. It can be carried out.

In order to monitor the light emission from the atmosphere side above the microwave introduction window 7, the microwave introduction window 7 and the shower plate 8 are transparent and need to transmit light. In general, the material is opaque because the surface roughness is large and light is diffusely reflected just by cutting quartz, and additional transparency treatment is required.

The methods for making quartz transparent can be broadly divided into mechanical polishing and fire polish, which melts the surface with a flame. Mechanical polishing can achieve good flatness if the target is a simple flat surface, but it is difficult for a concave surface with a stepped portion. On the other hand, when the material is made transparent by fire polishing, the surface accuracy tends to deteriorate because the member is deformed by heat.

The microwave introduction window 7 is usually as thick as 30 mm or more and has a small amount of deformation due to heat in order to have strength to withstand atmospheric pressure. As a result, even if fire polishing is performed, the flatness can be reduced to 50 μm or less, and transparency can be achieved while ensuring a low tolerance acceptable as an industrial product.

On the other hand, the shower plate 8 is often thinned to 10 mm or less so that gas holes can be easily formed by laser processing. When the member is thin as described above, the amount of deformation due to heat is large, and the flatness after fire polishing is several hundred μm or more.

Since the flow path between the microwave introduction window 7 and the shower plate 8 is a flow path through which the first gas passes, if the flatness is poor, the space through which the gas flows is partially narrowed and the gas flow is biased, which is permissible. It may not be possible. Therefore, mechanical polishing is required to make a thin material such as the shower plate 8 transparent with good flatness.

In the configuration of FIG. 8, since the shower plate 8 has no stepped portion, the shower plate 8 can be made transparent by mechanical polishing with good flatness. As described above, the shower plate 8 and the microwave introduction window 7 can be made transparent with a tolerance that is acceptable as an industrial product, and the light emitted from the plasma processing chamber 9 can be observed from the atmosphere side.

According to this embodiment, since the light emission from the plasma processing chamber 9 can be monitored, it is possible to reliably detect the end point detection of plasma processing, and it is possible to prevent a decrease in product yield due to excessive processing or insufficient processing. ..

In addition, by monitoring the issuance and monitoring the status of the equipment, it is possible to catch the abnormality of the equipment in advance and take countermeasures before the abnormality occurs, so that it is possible to prevent the decrease in the operation rate of the equipment due to the occurrence of the abnormality. can.

Although the invention made by the present inventor has been specifically described above based on Examples, it is needless to say that the present invention is not limited to the above-mentioned Examples and can be variously modified without departing from the gist thereof. stomach. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

1 Microwave source 5 Circular waveguide 6 Cavity 7 Microwave introduction window 8 Shower plate 9 Plasma processing chamber 10 Electromagnetic coil 11 York 13 Inner cylinder 14 Gas supply plate 15 First gas supply means 16 Second gas supply means 19 Substrate to be processed 20 Substrate stage and high frequency electrode (board electrode)
21 Insulation plate 26 Gas hole 27,27-1,27-2 Second plasma 28 Second gas supply plate 29 Third gas supply means 30 Headpiece 32,33,34 Step portion 50 Vacuum chamber 100,200, 300,400 Plasma processing device 101 Luminous detector 102 Spectrometer

Claims (8)

A processing chamber in which the sample is plasma-processed, a high-frequency power source that supplies high-frequency microwave power for generating plasma, a magnetic field forming mechanism that forms a magnetic field in the processing chamber, and a sample table on which the sample is placed. In a plasma processing apparatus including the first gas supply plate for supplying the first gas to the processing chamber and the first gas supply plate arranged at the upper part of the processing chamber.
A second gas supply plate, which supplies the second gas to the processing chamber and is arranged below the first gas supply plate, is further provided.
The first gas supply plate has a plurality of holes formed in the center thereof.
The second gas supply plate has a circular opening in the center and has a circular opening in the center.
A plasma processing apparatus characterized in that the area of the opening is larger than the area of the region in which the hole is arranged. In the plasma processing apparatus according to claim 1,
A plasma processing apparatus characterized in that the diameter of the opening is smaller than the diameter of the sample. In the plasma processing apparatus according to claim 1,
A third gas supply plate for supplying the third gas to the processing chamber and arranged below the second gas supply plate is further provided.
The third gas supply plate is a plasma processing apparatus having a circular opening in the center. In the plasma processing apparatus according to claim 3,
A plasma processing apparatus characterized in that the diameter of the opening in the third gas supply plate is larger than the diameter of the opening in the second gas supply plate. In the plasma processing apparatus according to claim 3 or 4.
A plasma processing apparatus characterized in that the diameter of the opening in the third gas supply plate is smaller than the diameter of the sample. In the plasma processing apparatus according to any one of claims 1 to 5.
The first gas supply plate is a plasma processing apparatus having a protrusion protruding downward in the region. In the plasma processing apparatus according to claim 1,
The diameter of the opening is defined based on a predetermined magnetic field gradient of the magnetic field formed by the magnetic field forming mechanism.
The plasma processing apparatus, characterized in that the magnetic field gradient is the amount of change in the magnetic flux density per unit length in the height direction of the processing chamber. In the plasma processing apparatus according to any one of claims 1 to 7.
The second gas supply plate is a plasma processing apparatus characterized in that the second gas supply plate is in contact with the first gas supply plate via a protrusion having an outer peripheral portion protruding upward.

Images