KR100390532B1 - Plasma apparatus and method for processing the semiconductor device - Google Patents

Abstract

The present invention provides a grounded process chamber; A first electrode and a second electrode disposed in the processing chamber and facing each other to form a plasma processing space, the first electrode supporting the target object, and processing gas supply means for supplying a processing gas into the plasma processing space; ; 10. A plasma processing apparatus of a semiconductor device, comprising: means for supplying high frequency power to at least the first electrode to generate plasma of the processing gas in the plasma processing space, comprising: plasma generating means for generating a high density plasma in the processing chamber; A matching network that adjusts the bias power to tune a bias power supply for applying a bias voltage to the sample stage with a single frequency of power independently of the plasma generation, and an impedance that varies during discharge due to the plasma generation; A splitter for separating a bottom frequency and a bottom-up RF frequency added by a predetermined frequency to the bottom frequency, the frequency output from the matching network; Modulate When the high frequency power and the low frequency power are respectively connected to the susceptor, frequency modulation means for modulating the frequency having the fundamental frequency by applying a frequency modulation by a predetermined bottom-up RF frequency of the fundamental frequency is provided.

Description

Plasma processing apparatus for semiconductor device and processing method thereof {PLASMA APPARATUS AND METHOD FOR PROCESSING THE SEMICONDUCTOR DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus for a semiconductor device and a processing method thereof. In particular, when a plasma is generated in the processing chamber by applying high frequency power to a processing chamber in which a target object is placed, the etching rate is reduced in the atmosphere of the plasma. The present invention relates to a plasma processing apparatus for a semiconductor device that modulates high frequency and low frequency power in a state in which power is fixed to increase plasma density without increasing the plasma density.

In general, in the manufacturing process of a semiconductor device, for example, in a magnetron RIE apparatus, which is one of plasma processing apparatuses, high-frequency power is applied in a gas tightly configured processing chamber to generate a plasma, and the target object is placed in the processing chamber in the plasma atmosphere. An etching process is performed on the semiconductor wafer or the like. In this case, in order to improve the etching rate by increasing the plasma density, for example, high frequency power with a frequency of 13.56 MHz is applied to the AC power supply.

However, when a high frequency power of a single frequency is applied in this manner, in the magnetron RIE apparatus, as shown in FIG. 2, only the electrons having high mobility are moved and charged due to the application of the high frequency power. (charge up) occurs. Therefore, the magnetron RIE apparatus is charged with electrons having high mobility on the surface of the semiconductor wafer so as to be charged, resulting in inclination of dislocations, and as a result, the device may be destroyed by charging up. For this reason, at least two power application means for providing high frequency and low frequency power for preventing charge-up are required.

Accordingly, an object of the present invention is to provide one electric power without at least two power applying means for providing high frequency and low frequency power for performing plasma processing of a semiconductor device in an atmosphere of plasma in a processing chamber in which a target object is placed in view of the above problems. The present invention provides a plasma processing apparatus for a semiconductor device and a method for processing the same, which have a power unit for applying only a high frequency power to modulate the high frequency power by low frequency power, thereby improving the selectivity in the etching density of the plasma processing of the semiconductor device. .

1 is a schematic view showing a magnetron RIE device used in one embodiment of a plasma processing method of a semiconductor device of the present invention.

2 is a schematic explanatory diagram for explaining a state where a semiconductor wafer is charged up;

FIG. 3 is a schematic diagram showing a power unit used in the magnetron RIE apparatus shown in FIG.

4 is a graph showing a relationship between a spectrum and an amplification degree of a bias power supply for frequency modulation from the power supply device of FIG.

FIG. 5 is a graph showing the relationship between the spectrum and the amplification degree of the fundamental wave and the integral wave when the sour wave (saw wave) is obtained by frequency modulation using the power supply device shown in FIG.

* Description of the symbols for the main parts of the drawings *

1: magnetron RIE apparatus 2: processing chamber

3: exhaust port 4: exhaust means

7: susceptor support 8: susceptor

11 coolant discharge pipe 20 matching network 21 modulator

22: low frequency power source 23: high frequency power source

24: blocking capacitor 25: controller

30: power supply device 31: electrostatic chuck

33: high voltage DC power supply 42: upper electrode

50: power unit 212: combine device

213: wideband frequency amplifier 216: splitter

A: Attenuator

A1 to An, 103: variable attenuator (rising part)

G1 to Gn: Oscillator G: Oscillator

W: semiconductor wafer

In order to achieve the object of the present invention, the plasma processing of the semiconductor device of the present invention, a grounded processing chamber; A first gas and a second electrode disposed in the processing chamber and opposed to each other to form a plasma processing space therebetween, the first electrode supporting the object to be processed, and a processing gas for supplying the processing gas into the plasma processing space; Supply means; 10. A plasma processing apparatus of a semiconductor device comprising means for supplying high frequency power to at least the first electrode to generate plasma of the processing gas in the plasma processing space,

Plasma generating means for generating a high density plasma in the processing chamber;

A bias power supply for applying a bias voltage to the sample stage with a single frequency of power independently of the plasma generation;

A matching network for adjusting the bias power to tune the impedance that varies during discharge due to the plasma generation;

A splitter installed in the matching network, the frequency output from the matching network is a splitter for separating a bottom frequency and a bottom-up RF frequency to which a predetermined frequency is added to the bottom frequency;

When the bias power supply is modulated by the low frequency power to the high frequency power and connects the high frequency power and the low frequency power to the susceptor, respectively, frequency modulation is performed by a predetermined bottom-up RF frequency of the fundamental frequency to the power having the fundamental frequency. It is provided with a frequency modulating means for modulating by adding.

In addition, the plasma processing method of the semiconductor device of the present invention

Placing a sample on a sample stage installed in the processing chamber;

Continuously supplying a processing gas into the processing chamber and simultaneously converting the processing gas into a plasma;

Applying a high frequency bias of a single frequency to the sample stage independently of the plasma generation;

Modulating a frequency by on / off control of the high frequency bias at a frequency of 100 Hz to 10 KHz;

And subjecting the sample to surface treatment by applying the high frequency bias voltage.

Therefore, in the present invention, the low frequency power is partially applied to the high frequency power to be modulated to neutralize the charge on the workpiece by the movement of ions without lowering the plasma density.

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

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing a magnetron RIE apparatus 1 used in carrying out an embodiment of the plasma processing method according to the first invention of the present invention. First, in the present invention, high frequency power means that plasma dissociation efficiency is good. The frequency is 10MHz or more, and low frequency power means that the frequency does not exceed 10MHz for convenience. However, as mentioned above, the frequency of the low frequency power applied by modulation is preferably 3 MHz or less, particularly 2 MHz or less. That is, the movement of ions and electrons in the plasma is made in accordance with the change in the alternating electric field.

This magnetron RIE apparatus 1 is made of aluminum or the like and has a processing chamber 2 which is an electrically grounded airtight container. First and second permanent magnets 27 and 28 are installed above the processing chamber 2. An exhaust pipe 5 connected to an exhaust means 4 such as a vacuum pump is connected to the exhaust port 3 provided at the bottom of the processing chamber 2. The evacuation means 4 allows the inside of the processing chamber 2 to be vacuumed evenly from the bottom periphery thereof, and can be set and maintained in a predetermined decompression atmosphere, for example, in a range of several tens of Torr.

A susceptor support 7 is installed in the center of the bottom of the processing chamber 2 through an insulating plate 6 made of ceramic or the like, and an upper surface of the susceptor support 7 is made of aluminum or the like to form a lower electrode. The susceptor 8 is provided.

A coolant chamber 9 is formed inside the susceptor support 7, and introduces a coolant from the coolant introduction pipe 10 provided in the bottom of the process chamber 2 into the coolant chamber 9. It is comprised so that it may discharge | emit from the refrigerant | coolant discharge pipe 11 and circulates. In this way, the susceptor 8 is controlled to a desired temperature.

The magnetron RIE apparatus 1 further includes a power unit 50 for supplying power to the outside of the processing chamber 2, which is matched with a symbol MN from one power supply 30. A high frequency power source 23 and a low frequency power source 22 to which fixed power is input through the network 20 and the modulator 21 indicated by the symbol M are provided. The matching network 20, the modulator 21, A high frequency power supply 23 and a controller 25 denoted by the reference C which is connected to control the low frequency power supply 22.

Here, the high frequency power source 23 and the low frequency power source 22 in the power unit 50 are connected to the susceptor 8, respectively, and the high frequency power source 23 has a frequency of 10 MHz or more, for example, a frequency of 13.56 MHz. The low frequency power source 22 is configured to output low frequency power with a frequency of 100 KHz to 3 MHz, for example, 2 MHz. In addition, the modulator 21 frequency modulates the power input to the modulator 21 into the high frequency power source 23 and the low frequency power source 22. Thereafter, the modulated high frequency power source 23 and the low frequency power source 22 are applied to the susceptor 8 separately. At this time, the controller 25 controls to apply only the high frequency power from the high frequency power source 23 to the susceptor 8 in a normal state, and the low frequency power from the low frequency power source 22 is changed every predetermined time. The high frequency power from the high frequency power supply 21 is input for a predetermined time.

Next, the case where the etching process is performed with respect to the semiconductor wafer W using the magnetron RIE apparatus 1 which has the said structure is demonstrated.

First, the semiconductor wafer W which is an object to be processed is loaded into the processing chamber 2 from the load lock chamber (not shown) into the magnetron RIE apparatus 1 and placed on the electrostatic chuck 31. The semiconductor wafer W is sucked and held on the electrostatic chuck 31 by the application of the high-voltage DC power supply 33.

Subsequently, the inside of the processing chamber 2 is exhausted by the exhaust means 4, the processing gas, for example, CF ₄ gas is supplied into the processing chamber 2 from one gas inlet 45, and the processing chamber 2 is provided. The pressure inside is set to, for example, 10 mTorr. Subsequently, the first and second permanent magnets 27 and 28 are rotationally driven to apply a magnetic field such that a magnetic field of 100 G, for example, is formed near the center of the semiconductor wafer W.

On the other hand, plasma is generated in the processing chamber 2 by accelerating the high frequency power of 13.56 MHz from the high frequency power source 23 to the susceptor 8 as it is by the controller 25. Anisotropic etching by the reactive ions thus obtained is performed on the semiconductor wafer W. FIG.

In the plasma processing of the semiconductor device, when etching is performed at a high frequency of 13.56 MHz, as shown in FIG. 2, the inclination of the potential E occurs on the semiconductor wafer W, and the application of the high frequency power of 13.56 MHz is applied as it is. If it continues, the device may be destroyed by the charge-up eventually.

Thus, in order to prevent such charge-up in advance, the frequency modulator 21 causes the low frequency power supply 22 to be instructed by the controller 25 from one power supply device 30 installed in the power unit 50. From the high frequency power supply 23, a high frequency power of 23 MHz is applied, and a high frequency power of 13.56 MHz is modulated and then the high frequency power supply 23 and the low frequency power supply 22 are supplied to the susceptor 8. Apply each.

When modulation by low frequency power of 2 MHz is applied as described above, neutralization is caused by the movement of ions, the charge on the semiconductor wafer W is canceled, and destruction by the charge-up is prevented in advance.

In addition, the controller 25 may store the timing data recorded by the charge voltage on the semiconductor wafer W as described above and modulate it based thereon. After such modulation for a predetermined time, the modulation may be stopped again and etching may be continued by application of a high frequency power of 13.56 MHz from the high frequency power supply 23. These controls are performed by the controller 25.

FIG. 3 is a schematic diagram showing a configuration example of a power unit used in the magnetron RIE device shown in FIG. 1 of the present invention. FIG.

The power unit 50 is configured such that electric power from the power supply device 30 of FIG. 1 is applied to the susceptor 8 used in the plasma processing via the blocking capacitor 24. The frequency modulator 21 provided in the power unit 50 includes a fundamental wave oscillator Gl which oscillates a fundamental wave, for example, a square wave having a frequency of 380 KHz, and a sine wave which is a frequency of an integer multiple of the fundamental wave. Oscillator G composed of several oscillators G2 to Gn for oscillating, and attenuators composed of variable attenuators A1 to An provided respectively corresponding to the oscillators G1 to Gn. A), a mixing device (or combine device) 212 for mixing the output signals from the variable attenuators A1 to An in these attenuators A, and the output of this mixing device 212. A wideband frequency amplifying device 213 is provided for amplifying a signal. The wideband frequency amplifying device 213 is provided with a splitter 216, and is adapted to tune an impedance which varies during plasma discharge even if the plasma state does not change. The matching network 21 is connected. Here, the splitter 216 may be installed outside the modulation device 20 in addition to the wideband frequency amplifying device 213. The high frequency power source 23 and the low frequency power source 22 are respectively connected to the susceptor 8 in the matching network 21.

In FIG. 3, the splitter 216 installed in the matching network 21 uses a bottom frequency as a parameter and a bottom up RF frequency as a parameter a +. When b is referred to, the bottom frequency a and the bottom frequency are split into a bottom-up RF frequency a + b, in which a predetermined frequency is added. Herein, the predetermined bottom-up RF frequency a + b with respect to the bottom frequency a may be output at a frequency of 800 KHz to 150 MHz. More preferably, when the bottom RF frequency a is 800 KHz to 13.56 MHz in frequency splitting by the splitter 216, the bottom up RF frequency a + b is a bottom up RF from 800 KHz to 13.56 MHz. The frequency is added to the frequency. This bottom-up RF frequency can be up to 150 MHz. In other words, the splitter 216 for separating the frequency inputs a predetermined bottom-up RF frequency a + b to the bottom RF frequency a and the bottom RF frequency when inputting its bottom RF frequency a from 800 KHz to 13.56 MHz. Can be output at two frequencies added. Furthermore, the splitter 216 for separating the frequency inputs the bottom RF frequency from 800 KHz to 13.56 MHz, the bottom frequency, a predetermined bottom up RF frequency to the bottom RF frequency, and the bottom up RF frequency. Multiply by n (n = 1,2,3,4, ....) times and can output at one or more frequencies.

On the other hand, as a top-down scheme as opposed to the bottom-up scheme, the splitter 216 separating the frequency outputs the top RF frequency and the top RF frequency at 800 KHz to 13.56 MHz top down RF frequency when the top RF frequency is input at 150 MHz. It is a matter of course that each of the oscillators G1 to Gn and the variable attenuators A1 to An is controlled by the central controller 214, and any of the oscillators G1 to Gn is controlled. The oscillators operate in combination, and each attenuation of each oscillator operated is individually adjusted. Each of these output signals is input to the mixing device 212. Each signal from each of the variable attenuators A1 to An input to the mixing device 212 is synthesized and amplified by the wideband frequency amplifying device 213 to be used as power for plasma generation. The level shifter 215 is provided separately in the wideband frequency amplifying apparatus 213. The level shift of the waveform applied to the susceptor 55 is changed. It can be adjusted arbitrarily.

Since the power unit 50 has the configuration shown in Fig. 3, frequency modulation is performed on the power to be applied to generate a waveform most suitable for each etching process, thereby controlling dissociation of gas molecules of the processing gas. There is a number.

On the other hand, according to the power unit 50 of the magnetron RIE etching device 51, the waveform of the power applied to the susceptor 8 by frequency modulation can be arbitrarily obtained, and an optimum output waveform can be obtained according to the purpose. Can be.

4 and 5, FIG. 4 is a graph illustrating a relationship between a spectrum and an amplification degree of a bias power source for frequency modulation from the power supply device of FIG. 1, and FIG. 5 is a power supply device shown in FIG. 4. This is a graph showing the relationship between the spectrum and the amplitude of the fundamental wave and the integer wave when the sour wave (saw wave) is obtained by frequency modulation. For example, oscillator G1 oscillates the fundamental wave (for example, 380 kHz). From the oscillator after another oscillator G2, the frequency of the integral multiple of the fundamental wave F, for example, 2 times (760 kHz), 3 times (1140 kHz), 4 times (15200 kHz). For example, as shown in Fig. 4, the phases are shifted by 180 degrees for even-numbered outputs, and they are adjusted with each of the variable attenuators A1 to (An) in the same phase for odd-numbered waves. When synthesized in the apparatus 212, a sawtooth wave (sawtooth wave) as shown in Fig. 5 can be obtained.

When this sour wave is applied to the susceptor 8 of the process chamber 2, ion bonding of etching ions can be strengthened, and an etching rate can be improved.

In addition, such waveform operation can be performed by the control apparatus 25 and the peripheral device which is not shown in figure.

In this way, the frequency wave is modulated by appropriately combining the integer waves with respect to the fundamental wave, and the intensity of the ionic bond is controlled according to the type and mass of the etchant ions of various reactive gases, starting with the CF ₄ gas molecule described above. In addition, the dissociation of gas molecules can be controlled, whereby the etching rate can be improved to perform an etching process having a high selectivity.

In this embodiment, a high frequency of 40 MHz is applied to the upper electrode 42 and a high frequency of 13.56 MHz to the lower electrode 8, respectively, but the combination of numerical values of these frequencies is not limited. Numerical combinations of the frequencies of and the lower electrode can be varied, for example, 1 MHz and 380 KHz, 13.56 MHz and 13.56 MHz, 380 KHz and 380 KHz, respectively.

In addition, in the present embodiment, the case of the so-called top and bottom method in which a high frequency power is applied to both the upper electrode 42 and the lower electrode 8 has been described, but the present invention is not limited thereto. For example, the bottom only method may be applied to a so-called top only method in which a high frequency power is applied only to the upper electrode to ground the lower electrode.

In this embodiment, two power sources, a high frequency power supply 23 and a low frequency power supply 22, are used. However, in the case of frequency modulation, a plurality of power supply devices are used to control the controller 25, for example. The frequency may be changed as appropriate. Although the modulator 23 in the present embodiment is configured to perform frequency modulation, the present invention is not limited to this, and the modulator 23 may be modulated by amplitude modulation using an amplitude modulator that performs amplitude modulation. Effect is obtained. In the present embodiment, the case where the plasma etching apparatus is used as the plasma processing apparatus has been described, but the present invention is not limited to this, but other plasma processing apparatuses such as plasma ashing apparatus, plasma CVD apparatus, plasma sputter apparatus, etc. Of course, can also be applied.

As described above, according to the present invention, the frequency modulation results in a trade-off between the high frequency power and the low frequency power over time, and the charging up phenomenon is prevented by preventing the charging up of the object without substantially reducing the plasma density. It is possible to prevent the device from being destroyed.

Moreover, the structure for realizing it is also very simple, for example, it can apply to the plasma processing apparatus of the existing semiconductor device, and the modulation method at that time can also adopt a frequency modulation and an amplitude modulation method.

According to the present invention, in the plasma processing method of a semiconductor device, for example, frequency modulation is applied to a power having an arbitrary fundamental frequency starting at 380 KHz by a frequency of n times (n = integer) of the fundamental frequency. Power for plasma generation having a waveform different from a simple single sinusoidal wave can be obtained. Therefore, for example, in the case of the plasma etching process, dissociation of gas molecules can be suppressed, or ion bombides of the etchant ions can be controlled, and the selectivity can be improved to provide good anisotropic etching. Therefore, the etching rate can be further improved.

Claims (8)

A grounded process chamber; A first electrode and a second electrode disposed in the processing chamber and facing each other to form a plasma processing space, the first electrode supporting the target object, and processing gas supply means for supplying a processing gas into the plasma processing space; ; 10. A plasma processing apparatus of a semiconductor device comprising means for supplying high frequency power to at least the first electrode to generate plasma of the processing gas in the plasma processing space, Plasma generating means for generating a high density plasma in the processing chamber; A bias power supply for applying a bias voltage to the sample stage with a single frequency of power independently of the plasma generation; A matching network for adjusting the bias power to tune the impedance that varies during discharge due to the plasma generation; A splitter installed in the matching network, the frequency output from the matching network is a splitter for separating a bottom frequency and a bottom-up RF frequency to which a predetermined frequency is added to the bottom frequency; When the bias power source is modulated by low frequency power to high frequency power, and the high frequency power and low frequency power are respectively connected to a susceptor, frequency modulation is performed by a predetermined bottom-up RF frequency of the fundamental frequency to power having a fundamental frequency. And a frequency modulating means for adding and modulating. The method of claim 1, And said predetermined bottom-up RF frequency is output at 800 KHz to 150 MHz. The method of claim 1, The splitter for separating the frequency multiplies the bottom RF frequency with the bottom RF frequency by a predetermined bottom-up RF frequency and multiplies the bottom-up RF frequency by an integer multiple when the bottom RF frequency is input from 800 KHz to 13.56 MHz. A plasma processing apparatus for a semiconductor device, which can be output at one or more frequencies. The method of claim 1, The splitter for separating the frequency is capable of outputting a top RF frequency and a top down RF frequency of 800 KHz to 13.56 MHz when the top RF frequency thereof is input at 150 MHz. delete delete delete delete