KR100960424B1 - Microwave plasma processing device - Google Patents

Abstract

The present invention provides a chamber in which a target object is to be accommodated, processing gas supply means for supplying a processing gas into the chamber, a microwave generation source for generating microwaves to form a plasma of the processing gas in the chamber, and a microwave generation source. A planar antenna comprising a waveguide means for guiding microwaves toward the chamber, a conductor having a plurality of microwave radiation holes for radiating microwaves guided by the waveguide means toward the chamber, and a ceiling wall of the chamber, A microwave transmitting plate made of a dielectric that transmits microwaves passing through the microwave radiation hole of the planar antenna, and provided on the opposite side to the microwave transmitting plate of the planar antenna, shortens the wavelength of the microwave reaching the planar antenna. function Which is a microwave plasma processing apparatus having a dashboard support made of a dielectric material. The planar antenna and the microwave transmitting plate are in close contact with substantially no air therebetween, and the slow wave plate and the microwave transmitting plate are formed of the same material, and the slow wave plate, the flat antenna, the microwave transmitting plate, and The equivalent circuit formed by the plasma of the processing gas formed in the chamber satisfies the resonance condition.

Description

Microwave Plasma Processing Equipment {MICROWAVE PLASMA PROCESSING DEVICE}

The present invention relates to a microwave plasma apparatus for processing a target object by microwave plasma.

Plasma treatment is an indispensable technique for the manufacture of semiconductor devices. In recent years, due to the request for higher integration and higher speed of LSI, the design rules of the semiconductor elements constituting the LSI have become increasingly finer. In addition, semiconductor wafers are being enlarged. Therefore, also in the plasma processing apparatus, such a design rule is required to cope with miniaturization and enlargement of a semiconductor wafer.

By the way, in the parallel plate type and inductive coupling type | mold plasma processing apparatus conventionally used abundantly, since the electron temperature used is high, plasma damage will generate | occur | produce in a microelement. In addition, since a region having a high plasma density is limited, it is difficult to plasma process a large semiconductor wafer uniformly and at high speed.

Thus, attention has been paid to a radial line slot antenna (RLSA) microwave plasma processing apparatus capable of uniformly forming a high density and low electron plasma (for example, Japanese Patent Laid-Open No. 2000-294550).

The RLSA microwave plasma processing apparatus is provided with a planar antenna (Radial Line Slot Antenna) in which a plurality of slots of a predetermined pattern are formed in the upper portion of the chamber. Then, microwaves derived from the microwave source are radiated from the slot of the planar antenna toward the chamber. This microwave is radiated in a chamber maintained in a vacuum via a microwave transmission plate made of a dielectric provided under the planar antenna. By this microwave electric field, the gas introduced into the chamber becomes plasma. In this way, the to-be-processed object, such as a semiconductor wafer, is plasma-processed by the plasma formed.

According to this RLSA microwave plasma processing apparatus, a high plasma density can be realized over a large area immediately under the antenna, and it is possible to perform a uniform plasma processing in a short time. In addition, since plasma of low electron temperature is formed, damage to the device is also small.

In this RLSA microwave plasma processing apparatus, in order to stabilize the plasma mode by adjusting the microwave electric field distribution in the microwave transmission plate, a technique for providing an air gap between the planar antenna and the microwave transmission plate is known (Jpn. Appl. Phys. 38 (1999) pp. 2082-2088 Part 1, No. 4A, April 1999).

However, if an air gap is provided between the planar antenna and the microwave transmitting plate, the impedance of the air gap is higher than that of the dielectric constituting the microwave transmitting plate, so that the microwave power loss in the air gap is increased. As a result, the microwave power efficiency decreases, or abnormal discharge inside the antenna easily occurs.

Gist of invention

This invention is made | formed in view of such a situation, Comprising: It aims at providing the microwave plasma processing apparatus for which the loss of microwave power is small, microwave power efficiency does not fall, and abnormal discharge in an antenna is hard to generate | occur | produce.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, this invention provides the chamber which accommodates a to-be-processed object, the process gas supply means which supplies a process gas in the said chamber, and the microwave generation source which produces the microwave which forms the plasma of the said process gas in the said chamber. And a planar antenna comprising a wave guide means for guiding microwaves generated from a microwave source toward the chamber, a conductor having a plurality of microwave radiation holes for radiating microwaves guided by the wave guide means toward the chamber, and the chamber A microwave transmissive plate made of a dielectric and transmitting microwaves passing through microwave radiation holes of the planar antenna, and opposite to the microwave transmissive plate of the planar antenna, Do not reach the flat antenna And a slow wave plate made of a dielectric having a function of shortening the wavelength of microwaves, wherein the planar antenna and the microwave transmission plate are closely contacted with no air therebetween, The microwave transmitting plate is formed of the same material, and the equivalent circuit formed by the slow wave plate, the planar antenna, the microwave transmitting plate, and the plasma of the processing gas formed in the chamber satisfies the resonance condition. It is a microwave plasma processing apparatus.

According to the present invention, since the plane antenna and the microwave transmission plate are in close contact with each other and no air gap is formed as in the prior art, microwave power loss does not occur due to the air gap. It can make it difficult to generate an abnormal discharge.

Here, simply removing the air gap may increase the reflection of the microwaves and deteriorate the stability of the plasma. However, according to the present invention, since the slow wave plate, the planar antenna, the microwave transmissive plate, and the equivalent circuit formed by the plasma are to be resonated, the microwave reflection is minimized, and the slow wave plate and the microwave transmissive plate are made of the same material. Since the surface reflection of microwaves is prevented, the plasma can be stably maintained.

The present invention also provides a chamber in which a target object is to be accommodated, processing gas supply means for supplying a processing gas into the chamber, a microwave generation source for generating microwaves for forming a plasma of the processing gas in the chamber, and a microwave generation source. A planar antenna comprising a wave guide means for guiding a microwave to be directed toward the chamber, a conductor having a plurality of microwave radiation holes for radiating the microwave guided by the wave guide toward the chamber, and a ceiling wall of the chamber, And a microwave transmissive plate made of a dielectric that transmits microwaves passing through the microwave radiation hole of the planar antenna, and opposite to the microwave transmissive plate of the planar antenna, and shortens the wavelength of the microwave reaching the planar antenna. doing And a slow wave plate made of a dielectric material, wherein the planar antenna and the microwave transmission plate are in close contact with substantially no air therebetween, and the slow wave plate and the microwave transmission plate have a ratio of their dielectric constant values of 70 The equivalent circuit formed of the material of% to 130%, and formed by the slow wave plate, the planar antenna, the microwave transmission plate, and the plasma of the processing gas formed in the chamber, satisfies the resonance condition. It is a microwave plasma processing apparatus.

According to the present invention, since the plane antenna and the microwave transmission plate are in close contact with each other and no air gap is formed as in the prior art, microwave power loss does not occur due to the air gap. It can make it difficult to generate an abnormal discharge.

Here, simply removing the air gap may increase the reflection of the microwaves and deteriorate the stability of the plasma. However, according to the present invention, since the slow wave plate, the planar antenna, the microwave transmitting plate, and the equivalent circuit formed by the plasma are to be resonated, the reflection of the microwave is minimized, and the slow wave plate and the microwave transmitting plate are Since the material has a ratio of the dielectric constant of 70% to 130%, the interface reflection of the microwave is prevented, and the plasma can be stably maintained.

Also in all the above inventions, the thickness of the microwave transmitting plate is in the range of 1/2 to 1/4 of the wavelength of the microwave to be introduced, more preferably in the range of 1/2 to 1/3, Microwave reflectances range from 0.4 to 0.8. According to these conditions, the equivalent circuit can satisfy the resonance condition.

The waveguide means includes a rectangular waveguide for propagating microwaves generated from the microwave source in TE mode, a mode converter for converting TE mode to TEM mode, and a coaxial waveguide for propagating microwaves converted to TEM mode toward the planar antenna. It can employ | adopt having.

In addition, each of the plurality of microwave radiation holes formed in the planar antenna has an elongated groove shape, and two adjacent microwave radiation holes are disposed in a direction crossing each other to form a pair of microwave radiation holes, and a plurality of microwave radiation It is preferable that the pair of holes is arranged in a concentric shape.

In addition, a cover for covering the slow wave plate and the flat antenna may be further provided. In this case, it is preferable that the coolant flow path is provided in the cover, and the slow wave plate, the planar antenna, and the microwave transmitting plate are cooled by passing the coolant through the coolant flow path. In such a configuration, since there is no air gap, cooling of the microwave permeable plate, which has low thermal conductivity and poor cooling efficiency, can be sufficiently performed by the existence of the conventional air gap.

For example, the frequency of a microwave is 2.45 kHz, the dielectric constant of a slow wave plate and a microwave transmission plate is 3.5-4.5, and a microwave radiation hole is arrange | positioned in double.

For example, the slow wave plate and the microwave transmitting plate are quartz, and the microwave plasma device is preferably a plasma etching device or a plasma surface modification device.

Alternatively, the slow wave plate and the microwave transmissive plate are alumina, and the microwave plasma device is preferably a plasma CVD device.

1 is a cross-sectional view schematically showing a microwave plasma processing apparatus according to an embodiment of the present invention;

2 is a plan view showing the structure of a planar antenna;

3 shows an equivalent circuit formed of a slow wave plate, a planar antenna, a microwave transmitting plate, and a plasma;

4 (a) and 4 (b) are views for explaining the thickness of the microwave transmission plate,

5 is a diagram showing a simulation result of electric field distribution on the surface of a microwave transmission plate in the microwave plasma processing apparatus of the present invention;

6 is a graph showing a measurement result of an electron temperature distribution example in the microwave plasma processing apparatus of the present invention;

7 is a diagram showing an example of electron density distribution in the microwave plasma processing apparatus of the present invention;

FIG. 8 (a) is a diagram showing the results of simulation of the microwave electric field strength on the surface of the microwave transmission plate with respect to the microwave plasma processing apparatus according to the present invention, and FIG. 8 (b) is the conventional microwave plasma processing apparatus. The figure which shows the result of simulating the microwave electric field intensity | strength on the surface of a microwave transmission plate.

To practice the invention  Best form for

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

1 is a cross-sectional view schematically showing a microwave plasma processing apparatus according to an embodiment of the present invention.

The microwave plasma processing apparatus 100 is a RLSA microwave plasma processing apparatus for forming a plasma by radiating microwaves derived from a microwave source into a chamber using a planar antenna having a plurality of slots formed in a predetermined pattern. It is configured as.

The microwave plasma processing apparatus 100 has a substantially cylindrical chamber 1 that is hermetically sealed and grounded. The circular opening 10 is formed in the substantially center part of the bottom wall 1a of the chamber 1. The bottom wall 1a is provided with the exhaust chamber 11 which communicates with the said opening part 10 and protrudes downward. The susceptor 2 for horizontally supporting the wafer W which is a to-be-processed substrate is provided in the chamber 1. The susceptor 2 is made of ceramics such as AlN. The susceptor 2 is supported by a cylindrical support member 3 extending upward from the bottom center of the exhaust chamber 11. The support member 3 is also made of ceramics such as AlN. At the outer edge of the susceptor 2, a guide ring 4 for guiding the wafer W is provided. In the susceptor 2, a heater 5 of resistance heating type is embedded. The heater 5 heats the susceptor 2 by being fed from the heater power source 6. The said heat of the susceptor 2 heats the wafer W which is a to-be-processed object. In addition, a cylindrical liner 7 made of quartz is provided on the inner circumferential wall of the chamber 1.

The susceptor 2 is provided with a wafer support pin (not shown) for supporting and lifting the wafer W so that the susceptor 2 can be driven against the surface of the susceptor 2.

On the side wall of the chamber 1, a gas introduction member 15 having a ring shape is provided. The processing gas supply system 16 is connected to this gas introduction member 15. As a result, a predetermined process gas is introduced into the chamber 1 from the process gas supply system 16 via the gas introducing member 15. The gas introduction member may be arranged in a shower shape. As the processing gas, an appropriate gas is used depending on the type of plasma processing. For example, when performing oxidation treatment such as selective oxidation treatment of a tungsten gate electrode, Ar gas, H ₂ gas, O ₂ gas or the like is used.

The exhaust pipe 23 is connected to the side surface of the exhaust chamber 11. An exhaust device 24 including a high speed vacuum pump (atmospheric water pump) is connected to the exhaust pipe 23. By operating the exhaust device 24, the gas in the chamber 1 is uniformly discharged into the space 11a below the exhaust chamber 11 and exhausted through the exhaust pipe 23. Accordingly, the chamber 1 can be decompressed at a high speed up to a predetermined degree of vacuum, for example, 0.133 kPa.

On the side wall of the chamber 1, a carry-in and out port 25 for carrying in and out of the wafer W and a carry-in and exit 25 is carried out between the transfer chamber (not shown) adjacent to the plasma processing apparatus 100. The gate valve 26 which opens and closes is provided.

The upper part of the chamber 1 is an opening part. A ring-shaped support portion 27 is provided along the periphery of the opening. On this support part 27, the microwave permeation | transmission plate 28 which permeate | transmits a microwave is provided to be airtight with the sealing member 29 interposed. As a result, the inside of the chamber 1 is kept airtight. The microwave transmitting plate 28 is made of a dielectric such as ceramics such as quartz or Al ₂ O ₃ .

The disk-shaped flat antenna 31 is provided above the microwave transmission plate 28. The planar antenna 31 is disposed to face the susceptor 2 with the microwave transmissive plate 28 therebetween. This planar antenna 31 is engaged to the upper end of the side wall of the chamber 1. The planar antenna 31 consists of a conductor, for example a copper plate or an aluminum plate with a gold plated surface. The planar antenna 31 has a configuration in which a plurality of microwave radiation holes (slots) 32 are formed in a predetermined pattern. In other words, the planar antenna 31 constitutes an RLSA antenna. The microwave radiation hole 32 has a long groove shape, for example, as shown in FIG. 2. In the example of FIG. 2, two adjacent microwave radiation holes 32 are arranged in an intersecting direction, typically in a direction orthogonal as shown (in a "T" shape), and these microwave radiation holes 32 are provided. Pairs (set) of are arranged in a concentric shape. The length of each microwave radiation hole 32 and the arrangement interval of pairs (sets) of the microwave radiation holes 32 are determined depending on the wavelength of the microwaves and the like. In FIG. 2, the radial spacing Ar between the pairs (sets) of the microwave radiation holes 32 arranged in a concentric shape is a wavelength of microwaves in the slow wave plate 33 described later, and the center of the flat antenna 31 is shown. If the length from the innermost circumference microwave radiation hole 32 also matches Δr, a strong electric field is radiated from the planar antenna 31, which is preferable. In the example of FIG. 2, the 4-turn (quadruple) microwave radiation hole 32 is arrange | positioned. Each microwave radiation hole 32 may be made into arbitrary shapes, such as circular shape and circular arc shape. Moreover, the arrangement | positioning form of the microwave radiation hole 32 (set) is not specifically limited, either, For example, it can also arrange | position in spiral shape and radial shape other than concentric circles.

On the top surface of the planar antenna 31, a slow wave plate 33 made of a dielectric having a dielectric constant greater than that of vacuum is provided. The slow wave plate 33 has a function of shortening the wavelength of the microwave in the slow wave plate as compared with the wavelength of the microwave wave in the vacuum.

The shield cover 34 is provided in the upper surface of the chamber 1 so that the planar antenna 31 and the slow wave plate 33 may be covered. The shield cover 34 is made of metal such as aluminum or stainless steel, for example. The upper surface of the chamber 1 and the shield cover 34 are sealed by the sealing member 35.

The shield cover 34 is provided with a cooling water flow path 34a. By passing the cooling water through the cooling water flow path 34a, the planar antenna 31, the microwave transmitting plate 28, the slow wave plate 33, and the shield cover 34 can be cooled. Shield cover 34 is grounded.

An opening 36 is formed in the center of the shield cover 34. The waveguide 37 is connected to this opening 36. The microwave generator 39 is connected to the end of the waveguide 37 with a matching circuit 38 interposed therebetween. As a result, microwaves, for example, at a frequency of 2.45 GHz, which are generated by the microwave generator 39, are propagated to the planar antenna member 31 via the waveguide 37. As the microwave frequency, 8.35 GHz, 1.98 GHz, or the like can also be used.

The waveguide 37 has a circular cross-sectional coaxial waveguide 37a extending upward from the opening 36 of the shield cover 34, and a horizontal cross-sectional rectangular shape connected to the upper end of the coaxial waveguide 37a. Has a rectangular waveguide 37b. The mode converter 40 is provided in the edge part of the rectangular waveguide 37b with the coaxial waveguide 37a. The inner conductor 41 extends in the center of the coaxial waveguide 37a. The lower end of this inner conductor 41 is connected and fixed to the center of the planar antenna 31.

Each component of the plasma processing apparatus 100 is connected to the process controller 50 so as to be controlled by the process controller 50. In the process controller 50, a process manager visualizes and displays the operation status of each component of the plasma processing apparatus 100 or a keyboard for performing a command input operation or the like for managing each component of the plasma processing apparatus 100. A recipe processing method in which a user interface 51 including a display and the like and a control program or processing condition data for realizing various processes executed in the plasma processing apparatus 100 by the control of the process controller 50 are described. The stored storage unit 52 is connected.

If necessary, based on an instruction from the user interface 51 or the like, an arbitrary recipe processing method is called from the storage unit 52 and executed by the process controller 50. Accordingly, the desired processing is performed in the plasma processing apparatus 100 under the control of the process controller 50.

Next, the slow wave plate 33, the planar antenna 31, and the microwave transmitting plate 28 in the present embodiment will be described in more detail.

In this embodiment, as shown in Fig. 1, the planar antenna 31 and the microwave transmitting plate 28 are in close contact with each other, so that no air gap as in the prior art is formed. The slow wave plate 33 and the planar antenna 31 are also in close contact with each other. However, simply removing the air gap increases the reflection of the microwaves seen by the mode converter 40, resulting in poor plasma stability and poor microwave power efficiency.

Therefore, in this embodiment, the equivalent circuit as shown in FIG. 3 constituted by the slow wave plate 33, the planar antenna 31, the microwave transmitting plate 28, and the plasma formed is satisfied to satisfy the resonance condition. In addition, the slow wave plate 33 and the microwave transmitting plate 28 are made of the same material. By the equivalent circuit satisfying the resonance condition, the reflection of the microwave can be minimized. In addition, since the slow wave plate 33 and the microwave transmitting plate 28 are made of the same material, the interface reflection of the microwaves can be prevented. As a result, the efficiency of the microwave power can be maintained high while improving the stability of the plasma.

As shown in Fig. 3, the slow wave plate 33 and the microwave transmitting plate 28 function as a capacitor, the planar antenna 31 functions as a resistor, and the plasma functions as a coil. As shown in the equivalent circuit of FIG. 3, the capacitance of the slow wave plate 33 is C1, the capacitance of the microwave transmitting plate 28 is C2, the resistance of the planar antenna 31 is R, the inductance of the plasma is L, and If the frequency of the microwave is f, the following equation (1) must be established in order to be in a resonance state.

Where C is C = 1 / {(1 / C1) + (1 / C2)}.

In order to satisfy such resonance conditions, the thickness of the microwave transmissive plate 28 defining capacitance is 1/2 to 1/4 (1 / 2λ to 1 / 4λ) of the microwave wavelength in the microwave transmissive plate 28. ) And the microwave reflectance (power reflection coefficient) seen from the mode converter 40 of the planar antenna 31 are effective in the range of 0.4 to 0.8.

The magnitude of the capacitance included in Equation (1) that defines the resonance condition is inversely proportional to the thickness of the component member. Here, for the slow wave plate 33, since the thinner side can efficiently cool the planar antenna 31 and the microwave transmission plate 28, the thickness of the microwave transmission plate 28 (to the size of the capacitance C, The more dominant capacitance C2) is defined as the range where resonance can occur. If the thickness of the microwave transmission plate 28 is larger than 1/2 or smaller than 1/3 of the wavelength of the microwave to be introduced, the region satisfying the resonance condition is narrowed. In addition, when smaller than 1/4, it becomes difficult to resonate.

Here, as the thickness of the microwave permeable plate 28, as shown in Fig. 4A, when the shape is flat, the actual thickness d1 is used. When the capacitance of the microwave transmission plate 28 at that time is CF, its relative dielectric constant is? 0, and the surface area is S1, the following formula (2) is established.

On the other hand, when the microwave permeation plate 28 has a complicated shape, the thickness d2 obtained from the capacitance calculation formula is used as the thickness. That is, when the capacitance of the complicated microwave transmitting plate 28 is set to CC and the surface area is set to S2, the following formula (3) is established. Here, surface area S2 is necessarily required. Therefore, when d2 is difficult to be obtained due to a complicated shape, after measuring the capacitance CC, it is inverted from the equation (3) to obtain the equivalent thickness d2, which can be the thickness of the microwave transmitting plate 28.

In addition, equivalent thickness d2 at this time is corresponded to the average thickness of unevenness | corrugation, as shown to FIG. 4 (b). As for the microwave reflectance of the planar antenna 31, if it is lower than 0.4, it is difficult to adjust to the resonance condition because the change in phase when the frequency is changed is large, while if it exceeds 0.8, it is essentially a resonance condition. Becomes difficult to satisfy.

In addition, the slow wave plate 33 and the microwave transmitting plate 28 are preferably made of the same material. However, it is confirmed by simulation that even with different materials, if the ratio of their dielectric constants is in the range of 70% to 130%, it can be adjusted to resonance conditions.

In the plasma processing apparatus 100 configured as described above, first, the gate valve 26 is opened, and the wafer W serving as an object to be processed is loaded into the chamber 1 from the carry-in port 25. The wafer W is mounted on the susceptor 2.

Then, a predetermined processing gas is introduced from the gas supply system 16 into the chamber 1 via the gas introducing member 15 and maintained at a predetermined pressure. For example, in the case of performing an oxidation treatment such as a selective oxidation treatment of a tungsten gate electrode, Ar gas, H ₂ gas, O ₂ gas, or the like is introduced into the chamber 1 as the processing gas, and the pressure in the chamber 1 is, for example. For example, it becomes 3 ~ 700㎩.

Subsequently, microwaves from the microwave generator 39 are guided to the waveguide 37 through the matching circuit 38. The microwaves are sequentially passed through the rectangular waveguide 37b, the mode converter 40, the coaxial waveguide 37a, and the slow wave plate 33, and are supplied to the planar antenna member 31. Microwaves also radiate from the planar antenna member 31 past the microwave transmissive plate 28 into the space above the wafer W in the chamber 1. Microwaves propagate in TE mode within rectangular waveguide 37b. The microwave in this TE mode is converted to the TEM mode in the mode converter 40. The microwave in this TEM mode propagates in the coaxial waveguide 37a toward the planar antenna member 31.

By the microwaves radiating from the planar antenna member 31 past the microwave permeable plate 28 to the chamber 1, the processing gas introduced into the chamber 1 is converted into plasma. By such a plasma, a predetermined process such as an oxidation process is performed.

The microwave plasma processing apparatus 100 of this embodiment can realize a high plasma density of about 10 ¹² / cm 3 or more and a low electron temperature plasma of about 1.5 eV or less. For this reason, plasma treatment can be performed at a low temperature and for a short time, and there is an advantage that plasma damage such as ions to the underlying film is small.

In addition, in the present embodiment, as shown in Fig. 1, the plane antenna 31 and the microwave transmitting plate 28 are in a state of being in close contact with each other. Microwave power loss does not occur due to the gap. In addition, it is possible to prevent the decrease in the microwave power efficiency and the abnormal discharge that is likely to occur between the gaps of the microwave radiation holes (slots) 32 in the antenna and around the slow wave plate 33.

However, simply removing the air gap may increase the reflection of the microwaves seen by the mode converter 40, resulting in poor plasma stability. On the other hand, in this embodiment, the equivalent circuit composed of the slow wave plate 33, the planar antenna 31, the microwave transmitting plate 28, and the plasma formed is caused to resonate, thereby minimizing the reflection of the microwaves. can do. In addition, since the slow wave plate 33 and the microwave transmitting plate 28 are made of the same material, the interface reflection of the microwaves can be prevented. As a result, while maintaining the plasma stably, it is difficult to reduce the microwave power efficiency or to generate abnormal discharges inside the antenna. In addition, the planar antenna 31 and the microwave transmitting plate 28 may be in close contact with substantially no air therebetween. That is, even if there are some gaps due to adhesion error, thermal expansion, or the like, it is allowed to be 0.1 mm or less (included in the present invention).

In addition, there is no air gap with low thermal conductivity between the planar antenna 31 and the microwave transmitting plate 28. For this reason, when cooling water flows through the cooling water flow path 34a formed in the shield cover 34 to cool the planar antenna 31, the microwave transmitting plate 28, the slow wave plate 33, and the shield cover 34, It is possible to efficiently cool the microwave transmission window 28 which has conventionally had a poor cooling efficiency.

Next, an experiment conducted to confirm the effect of the present invention will be described.

Here, the following slow wave plate 33, planar antenna 31 and microwave transmitting plate 28 were used.

Slow wave plate: Quartz, diameter 329mm thickness 7mm

Flat antenna: diameter φ344 mm, thickness 0.3 mm

Microwave permeable plate: quartz, diameter 362mm, thickness 31.3mm (= 1 / 2λ),

         Flat type, one-piece integrated with flat antenna

In addition, electrical characteristics were set as follows.

Frequency: 2.45 GHz

Power Density: 2.67 W / cm 2 (at 2750 W), 2.91 W / cm 2 (at 3000 W)

Input impedance: 50 Ω (2.45 Ω)

Power reflection coefficient: 0.75 (2.45 Hz)

Under the above conditions, the electric field distribution in the microwave transmission plate was simulated. As the analysis conditions, as shown in FIG. 5, the plasma radiation holes (slots) each have an elongated groove shape, and two adjacent microwave radiation holes 32 are arranged in an “L” shape, and these “ Pairs (sets) of L ''-shaped microwave radiation holes 32 were arranged in a concentric manner in a double manner, and the plasma density was 1 × 10 ¹² / cm 3. As a result, as shown in Fig. 5, the electric field distribution is relatively uniform, and there are many parts of high electric field strength of 3 × 10 ² V / m or more, and parts of 4 × 10 ² V / m or more, so that the loss of microwave power This little thing was confirmed.

Next, under the above conditions, plasma was actually formed, and the electron temperature distribution and the electron density distribution were obtained. At that time, Ar was used as the processing gas, the pressure in the chamber was 1 Torr (133 kPa), and the microwave power was 2750 W. The electron temperature distribution is shown in FIG. 6, and the electron density distribution is shown in FIG.

As shown in FIG. 6, the electron temperature is 1.6 eV or less, and the distribution gap is small. As shown in Fig. 7, the electron density is almost 1x10 < ¹² > / cm < 3 > That is, it was confirmed that the plasma of high density was formed stably at low electron temperature.

Next, the results of the simulation of the microwave electric field strength in the microwave transmission plate will be described for the microwave plasma processing apparatus according to the present invention and the microwave plasma processing apparatus having a conventional air gap. In the case of the microwave plasma processing apparatus of the present invention, the slow wave plate 33, the planar antenna 31, the microwave transmitting plate 28, and the electrical characteristics were similar to the above experiments, and the plasma density was 1 × 10 ¹⁰ / cm 3. . In the case of the conventional microwave plasma processing apparatus, in addition to these, the length (thickness) of the air gap was set to 20 mm. Each result is shown to FIG. 8 (a) and FIG. 8 (b). As shown in Fig. 8A, in the apparatus of the present invention, a portion of high microwave field strength of 1.75 × 10 ¹ V / m or more is seen. However, as shown in Fig. 8B, in the conventional apparatus, there are many low portions of 5 V / m or less. That is, it turned out that microwave electrolysis intensity becomes remarkably higher than before with this invention. In addition, it has been found that a great difference is not seen in the present invention and the prior art regarding the uniformity of the microwave electric field strength.

In a preferred semiconductor manufacturing apparatus based on the spirit of the invention as one explained so far, the microwave transmitting plate 28 and the support dashboard unit 33 is constituted by an alumina (Al ₂ O _3), or, these are quartz It may be a device composed of the (SiO _2).

A plasma CVD apparatus is mentioned as an example to which the apparatus by which the microwave permeation | transmission plate 28 and the slow wave plate 33 consist of alumina is suitably applied. When a gas containing an element constituting the microwave permeation plate 28 is generated by the reaction between the microwave permeation plate 28 and active species of the plasma, the gas is taken into the film to be formed on the object to be deteriorated. There is a possibility. Here, when the microwave permeable plate 28 is made of alumina, the alumina is dense, so that, for example, the amount of oxygen released can be reduced to about one order of magnitude lower than that of quartz or the like. For example, the microwave transmission plate 28 and the slow wave plate 33 may be formed of another material having a dielectric constant close to that of alumina formed by laminating alumina and another material. In this case, materials having a relative dielectric constant in the range of 7.4 to 9.6 can be variously combined so that the ratio of the value of the dielectric constant is between 70% and 130%, which can satisfy the resonance condition.

On the other hand, a plasma etching apparatus or a plasma surface modification apparatus is mentioned as an example to which the apparatus by which the microwave permeation | transmission plate 28 and the slow wave plate 33 are comprised by quartz is applied. In the process conditions for etching and surface modification, the microwave permeable plate 28 is sputtered by ion bombardment. At this time, when the element which comprises the microwave permeation | transmission plate 28 contains metal, there exists a possibility that a metal contamination may be caused to a to-be-processed object. Thus, for example, alumina or the like cannot be used. In this case, if the microwave permeable plate 28 is made of quartz, in most cases, the object to be treated is also a silicon wafer or a glass substrate, and since these and quartz are based on the same elemental Si, there is no cause of metal contamination.

In addition, in the apparatus comprised of the microwave permeation | transmission plate 28 and the slow wave plate 33 and quartz, the radial space | interval of the microwave radiation hole 32 arrange | positioned concentrically and the center of the planar antenna 31 are the most. If the length to the inside of the microwave radiation hole 32 is set to Ar (see Fig. 2), and Δr = (wavelength of the microwaves in the wave plate), the microwave radiation hole 32 is used when the microwave frequency is 2.45 Hz. ) Is two turns (placed). Here, as the planar antenna 31, the apparatus which processes the 300-mm wafer which is the mainstream of the present is assumed, In other words, the diameter of the planar antenna 31 is also set to about 300 mm. On the other hand, if the microwave permeation plate 28 and the slow wave plate 33 are alumina, the microwave radiation hole 32 is formed (arranged) three turns. In comparison between the two-turn devices, the design and adjustment of slots is extremely difficult compared to the two-turn devices. For example, in a three-turn device, even if the number of slots in the middle turn is increased, the plasma density immediately below it does not increase, but the center density of the plasma space decreases, so that the density of the outer circumference may increase, or vice versa. Can be. This is because the microwaves radiated from the slots of the intermediate turns interfere with each other with the electromagnetic waves radiated from the slots of the inner and outer turns. In view of this, as the material constituting the microwave permeable plate 28 and the slow wave plate 33, quartz having two turns of the microwave radiation holes 32 is preferable. For example, the microwave transmission plate 28 and the slow wave plate 33 may be formed of a different material having a dielectric constant close to quartz formed by laminating quartz and another material. In this case, materials having a relative dielectric constant in the range of 3.5 to 4.5 can be variously combined so that the ratio of the dielectric constant values is between 70% and 130%, which can satisfy the resonance condition. Also in this case, when the microwave permeation plate 28 and the slow wave plate 33 have a microwave frequency of 2.45 kHz as in the case of quartz, the microwave radiation holes 32 are formed (arranged) by two turns.

In addition, this invention is not limited to the said Example, It can variously change. For example, the configuration of the processing apparatus is not limited to the above embodiments as long as the configuration requirements of the present invention are satisfied. In addition, the target plasma treatment is not limited to the oxidation treatment, and can be applied to various processes such as a film formation treatment and an etching treatment. The object to be subjected to the plasma treatment is not limited to a semiconductor wafer, but may be another one such as a flat panel display substrate.

The present invention as described above is suitable for plasma processing in which low electron temperature and high density plasma are required, such as oxidation treatment, film formation treatment, and etching treatment in a semiconductor device manufacturing process.

Claims (10)

A chamber in which the object to be processed is accommodated, Process gas supply means for supplying a process gas into the chamber; A microwave generation source for generating microwaves to form a plasma of the processing gas in the chamber; Wave guide means for guiding microwaves generated from the microwave source toward the chamber; A planar antenna comprising a conductor having a plurality of microwave radiation holes for radiating the microwaves guided by the waveguide means toward the chamber; A microwave transmissive plate constituting a ceiling wall of the chamber and transmitting a microwave passing through the microwave radiation hole of the planar antenna; A slow wave plate made of a dielectric provided on the opposite side to the microwave transmitting plate of the planar antenna and having a function of shortening the wavelength of the microwave reaching the planar antenna. Provided with The planar antenna and the microwave transmitting plate are in close contact with no air therebetween, The slow wave plate and the microwave transmission plate is formed of the same material, An equivalent circuit formed by the slow wave plate, the planar antenna, the microwave transmitting plate, and the plasma of the processing gas formed in the chamber, the capacitance of the slow wave plate is C1, the capacitance of the microwave transmitting plate is C2, If the resistance of the planar antenna is R, the inductance of the plasma is L, and the frequency of the microwave is f,

Where C is C = 1 / {(1 / C1) + (1 / C2)} Satisfying resonant conditions of Microwave plasma processing apparatus, characterized in that. A chamber in which the object to be processed is accommodated, Process gas supply means for supplying a process gas into the chamber; A microwave generation source for generating microwaves to form a plasma of the processing gas in the chamber; Wave guide means for guiding microwaves generated from the microwave source toward the chamber; A planar antenna comprising a conductor having a plurality of microwave radiation holes for radiating the microwaves guided by the waveguide means toward the chamber; A microwave transmissive plate constituting the ceiling wall of the chamber and transmitting a microwave passing through the microwave radiation hole of the planar antenna; A slow wave plate made of a dielectric provided on the opposite side to the microwave transmitting plate of the planar antenna and having a function of shortening the wavelength of the microwave reaching the planar antenna. Provided with The planar antenna and the microwave transmitting plate are in close contact with no air therebetween, The slow wave plate and the microwave transmission plate are formed of a material in which the ratio of their dielectric constants is 70% to 130%, An equivalent circuit formed by the slow wave plate, the planar antenna, the microwave transmitting plate, and the plasma of the processing gas formed in the chamber, the capacitance of the slow wave plate is C1, the capacitance of the microwave transmitting plate is C2, If the resistance of the planar antenna is R, the inductance of the plasma is L, and the frequency of the microwave is f,

Where C is C = 1 / {(1 / C1) + (1 / C2)} Satisfying resonant conditions of Microwave plasma processing apparatus, characterized in that. The method according to claim 1 or 2, The thickness of the microwave transmission plate is in the range of 1/2 to 1/4 of the wavelength of the microwave to be introduced, Microwave reflectance of the planar antenna is in the range of 0.4 ~ 0.8 Microwave plasma processing apparatus, characterized in that. The method of claim 3, wherein The waveguide means includes a rectangular waveguide for propagating microwaves generated from the microwave source in TE mode, a mode converter for converting TE mode to TEM mode, and a coaxial waveguide for propagating microwaves converted to TEM mode toward the planar antenna. Microwave plasma processing apparatus having a. The method of claim 3, wherein Each of the plurality of microwave radiation holes formed in the planar antenna forms a long groove shape, Two adjacent microwave radiation holes are disposed in a direction crossing each other to form a pair of microwave radiation holes, Having a plurality of pairs of microwave radiation holes arranged concentrically Microwave plasma processing apparatus, characterized in that. The method of claim 3, wherein And a cover for covering the slow wave plate and the planar antenna. The method of claim 6, A coolant flow path is provided in the cover, and the slow wave plate, the planar antenna, and the microwave transmitting plate are cooled by flowing a coolant through the coolant flow path. The method of claim 3, wherein The frequency of the microwave is 2.45 kHz, The dielectric constant of the slow wave plate and the microwave transmitting plate is 3.5 to 4.5, The microwave radiation holes being arranged in duplicate Microwave plasma processing apparatus, characterized in that. The method of claim 3, wherein The slow wave plate and the microwave transmitting plate are quartz, The microwave plasma processing apparatus is a plasma etching apparatus or a plasma surface modification apparatus Microwave plasma processing apparatus, characterized in that. The method of claim 3, wherein The slow wave plate and the microwave transmitting plate are alumina, The microwave plasma processing apparatus is a plasma CVD apparatus Microwave plasma processing apparatus, characterized in that.

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