KR101299902B1 - Apparatus for measuring inductively coupled plasma uniformity and method of measuring using thereof - Google Patents

Abstract

An inductively coupled plasma uniformity measuring apparatus and a measuring method using the same are provided. An inductively coupled plasma uniformity measuring apparatus and a measuring method using the same include a space of an inductively coupled plasma source including a plurality of photometric cables connected to an upper portion of a dielectric window of an inductively coupled plasma generator, and a light quantity meter connected to the plurality of photometric cables. And a uniformity measuring device. Therefore, the indirect measurement method can be used to evaluate the spatial plasma uniformity of the entire surface of the large area inductively coupled plasma source. In addition, since the spatial plasma uniformity measurement is not directly measured in the vacuum chamber, the plasma uniformity at the time of plasma turn-on can be evaluated in near real time. Therefore, the spatial uniformity adjustment of the inductively coupled plasma source can be easily performed.

Description

Apparatus for measuring inductively coupled plasma uniformity and method of measuring using

The present invention relates to an inductively coupled plasma uniformity measuring apparatus and a measuring method using the same. More particularly, the present invention relates to an apparatus for measuring spatial uniformity of plasma generated in a vacuum plasma chamber and a measuring method using the same.

Plasma is a special type of gas with electrical energy that accelerates chemical reactions and accelerates the ions in the plasma to be used for dry etching, deposition or sputtering of the surface of the medium in contact with the plasma. In order to use the plasma reaction for surface treatment, it is important to control the electrical energy of the plasma.

Recently, plasma has been actively used in semiconductor manufacturing processes and display manufacturing processes. In the semiconductor manufacturing process, a dry etching process, a deposition process, an ashing process, an ALD (Atomic Layer Depostion), and the like are used in a display plate etching process and a display plate thin film deposition process.

Recently, the size of a substrate used to manufacture a flat panel display has become large in order to reduce manufacturing costs through improved throughput. Therefore, in the case of the equipment using the plasma among the vacuum process equipment for manufacturing a flat panel display, a level of plasma uniformity suitable for the process is required. Therefore, an inductively coupled plasma apparatus using RF discharge to form a plasma of uniform density is mainly used.

1 is a cross-sectional view showing an inductively coupled plasma generator according to the prior art.

Referring to FIG. 1, an inductively coupled plasma generator includes a plasma chamber 130, a plasma antenna 110, and a dielectric window 120.

The plasma chamber 130 is maintained in a vacuum state, and generates the plasma 160 using the process gas 170 introduced from the outside for processing the substrate.

A vacuum pump 200 is used to maintain the plasma chamber 130 in a vacuum state.

The plasma chamber 130 includes an electrostatic chuck 140 for fixing the substrate 150 injected into the chamber.

The plasma antenna 110 is positioned above the plasma chamber 130 and is connected to the high frequency power source 180 and the high frequency matching device 190 to induce an electric field for generating plasma in the plasma chamber 130.

Since the inductively coupled plasma generator needs to supply power in a place separated from the plasma and the dielectric window, high frequency power is supplied through the magnetic field. Therefore, the inductively coupled plasma generator has a coil antenna structure that is advantageous for generating magnetic fields.

The high frequency power source 180 supplies high frequency energy, and the high frequency matching device 190 reduces the loss of high frequency energy by matching impedance during the process.

The dielectric window 120 physically separates the plasma chamber 130 and the plasma antenna 110.

Unlike electrostatically coupled plasma generators in which a flat counter electrode is installed in a vacuum chamber, a plasma source and a plasma antenna 110 are disposed outside the plasma vacuum chamber with a dielectric window 120 in which quartz is generally used. Is installed.

Accordingly, magnetic force is generated by the influence of the high frequency current applied to the plasma antenna 110 installed outside the plasma vacuum chamber, and induced power is supplied to the plasma 160 through the dielectric window 120 by the generated magnetic force. Is generated.

In the case of flat panel displays, the size of the substrate to be used becomes large, and a substrate having a size of 2 m or more is used. Also, unlike semiconductor wafer substrates, asymmetric substrates having different horizontal and vertical lengths are used.

Therefore, the inductively coupled plasma source is also configured to have an asymmetric structure according to the shape of the substrate, and as the substrate becomes larger, the size of the antenna of the inductively coupled plasma source is required to correspond to the large area.

In this case, the antenna constituting the inductively coupled plasma source is limited in overall length because it must be controlled to have an appropriate impedance in order to induce and deliver efficient power.

In consideration of the practical efficiency, the configurable antenna length is used within a quarter wavelength range of the high frequency power frequency applied. Therefore, when the size of the substrate exceeds 1m in consideration of the antenna length limitation, inductively coupled plasma source that can correspond to the substrate area can be configured only by connecting a plurality of antennas in parallel or in parallel.

On the other hand, when the inductively coupled plasma antenna is configured to correspond to the asymmetric rectangular substrate in a plurality of arrays, it is practically difficult to configure the length and shape of the antenna identically according to the asymmetry of the substrate form.

Therefore, it is difficult to implement the arrangement of the antenna so that the transmission rate by spatial induction and spatial inductive coupling of high frequency power is uniform in all spaces.

In order to solve this problem, spatial uniformity of the antenna and tuning of the high frequency power supplied for each antenna are controlled based on the data obtained through the measurement of the uniformity of the generated plasma.

At this time, the spatial uniformity or the efficiency of the high frequency power supplied to the plasma according to the spatial arrangement of the antenna can be grasped to some extent through computer simulation, and based on this, it can be corrected through redesign.

However, in the case of actually manufacturing and driving, distortion in plasma uniformity may occur due to impedance deviation between antennas or various parasitic parameters.

Accordingly, there is a need for an apparatus for measuring plasma uniformity that enables the plasma source to be adjusted so that spatial plasma deviation can be compensated by measuring spatial uniformity of plasma generated using an inductively coupled plasma apparatus.

Conventionally, in order to check plasma uniformity, Langmuir probes were inserted into a vacuum chamber to directly measure the ion density of the plasma to determine the spatial uniformity of the plasma. However, there is a problem in that the measurement is possible only in the linear space due to the characteristic of the Langmuir probe.

Therefore, there is a need to develop a measuring apparatus that can grasp the three-dimensional spatial uniformity of the plasma rather than the linear space.

KR 10-2010-0105768 A 2010.09.29. KR 10-2006-0001944 A 2006.01.06.

The technical problem to be solved by the present invention is to provide a plasma uniformity measuring apparatus and a measuring method using the same to provide a reference to compensate for the spatial plasma deviation by measuring the spatial uniformity of the plasma generated in the inductively coupled plasma generator Is in.

According to an aspect of the present invention, a plurality of metering cables connected to an upper portion of a dielectric window of an inductively coupled plasma generator; And it provides a spatial uniformity measuring apparatus of the inductively coupled plasma source comprising a light quantity meter connected to the plurality of photometric cable.

The optical switch may further include an optical switch connected to the plurality of photometric cables and the light quantity meter and positioned between the plurality of photometric cables and the light quantity meter.

Another aspect of the present invention to achieve the above technical problem is a plurality of photometric cables connected to the upper portion of the dielectric window of the inductively coupled plasma generator; And an optical spectrum analyzer connected to the plurality of photometric cables.

The optical switch may further include an optical switch connected to the plurality of photometric cables and the optical spectrum analyzer and positioned between the plurality of photometric cables and the optical spectrum analyzer.

The light collecting lens may further include a light collecting lens connected to the light measuring cable, and the light collecting lens may be positioned between the dielectric window and the plurality of light measuring cables.

The light quantity meter may include an optical filter and an optical sensor.

In order to achieve the above technical problem, another aspect of the present invention provides a plasma chamber, a plasma antenna positioned above the plasma chamber, and an inductively coupled plasma generator including a dielectric window for physically separating the plasma chamber and the plasma antenna. Generating an inductively coupled plasma gas in the plasma chamber; Collecting the excited light from the generated plasma gas using a plurality of optical cables connected to an upper portion of the dielectric window of the inductively coupled plasma generator; And it provides a method for measuring the spatial uniformity of the inductively coupled plasma gas comprising the step of measuring the intensity of the light collected using the optical cable using a light quantity meter.

Before collecting the light, the method may further include collecting light excited in the plasma gas using a light collecting lens.

The method may further include switching the collected light by using an optical switch before measuring the intensity of the light.

As described above, according to the present invention, a method of comparing the spatial light intensity deviation by measuring the light intensity of the plasma on the outer surface of the plasma chamber, the entire substrate of the large area inductively coupled plasma source using an indirect measurement method The spatial plasma uniformity of the plane can be evaluated.

In addition, since the spatial plasma uniformity measurement is not directly measured in the vacuum chamber, the plasma uniformity at the time of plasma turn-on can be evaluated in near real time. Therefore, the spatial uniformity adjustment of the inductively coupled plasma source can be easily performed.

However, the effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

1 is a cross-sectional view showing an inductively coupled plasma generator according to the prior art.
Figure 2 is a cross-sectional view showing an inductively coupled plasma uniformity measuring apparatus according to an embodiment of the present invention.
3 is an image showing a position where the photometric cable is connected to the dielectric window.
4 is a graph showing light intensity for each measurement position before and after uniformity adjustment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. Like numbers refer to like elements throughout. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

Figure 2 is a cross-sectional view showing an inductively coupled plasma uniformity measuring apparatus according to an embodiment of the present invention.

Referring to FIG. 2, the spatial uniformity measuring apparatus of the plasma source includes a plurality of photometric cables 300, an optical switch 400, and a light quantity meter 500.

The plurality of metering cables 300 are connected to an upper portion of the dielectric window located above the plasma chamber.

The photometric cable 300 may be a UV-VIS Optical Fiber Cable.

Even without placing the measuring device directly in the plasma chamber, the light emitted from the plasma emitted through the dielectric window is collected using a photometric cable to measure the intensity of the light.

The metering cable 300 is preferably a plurality in order to measure the spatial uniformity of the plasma. The plurality of photometric cables 300 may be uniformly positioned on the dielectric window 120.

If the intensity of the plasma light emitted through the dielectric window is weak, the light collecting lens (not shown) may be connected to the photometric cable to collect the plasma light. In this case, the light collecting lens is located between the dielectric window and the photometric cable and is connected to the photometric cable.

The light collecting lens may be a collimation lens.

The optical switch 400 is connected to the plurality of photometric cables 300 and the light quantity meter 500, and is positioned between the plurality of photometric cables 300 and the light quantity meter 500. However, in some cases, the optical switch 400 may be omitted. If the optical switch is omitted, the plurality of photometric cables 300 may be directly converted into an electrical signal using a photometer 500 or an optical spectrum analyzer (not shown), collected by a computer, and the spatial uniformity of the plasma may be evaluated. have.

The optical switch 400 switches the collected light using the photometric cable 300.

The optical switch 400 may be an optical switch capable of switching 8 to 1 or 16 to 1 of the plurality of optical cables 300. In this case, the optical switch may be used to select the photometric cable 300 of the desired channel, and only the signal collected from the selected photometric cable 300 may be transmitted to the light quantity meter 500.

The light quantity meter 500 is connected to the optical switch 400. The light quantity meter 500 converts the light collected in the channel selected from the light switch 400 into an electrical signal corresponding to the light intensity.

The light quantity measuring device 500 may include an optical filter and an optical sensor. The optical filter transmits only light of a specific wavelength band and can selectively analyze the result. The optical sensor also converts the amount of transmitted light into an electrical signal.

The electrical signals converted by the light quantity measurer 500 may be collected through a computer to derive spatial light intensity. That is, the spatial distribution of the intensity of the amount of light of the intrinsic wavelength for each gas and the deviation for each measurement position are measured through the collected results. Then, the impedance between the antennas is adjusted based on the spatial deviation of the plasma uniformity as a reference for correcting the spatial high frequency power distribution deviation of the inductively coupled plasma source antenna.

An optical spectrum analyzer may be used in place of the photometer 500. The optical spectrum analyzer graphically displays level values for each wavelength, and thus it is easy to check whether the level values are attenuated for each wavelength.

3 is an image showing a position where the photometric cable is connected to the dielectric window.

Referring to FIG. 3, the position where the thirteen photometric cables 300 are connected to the dielectric window 120 is indicated by an “X” on the dielectric window 120 where the plasma antenna 110 is disposed.

Thirteen positions can be used to evaluate the process uniformity of the substrate. At this time, the measurement position of the spatial uniformity deviation of the plasma should be appropriately selected.

In addition, for very large areas, the metering cable can be connected to 23 or more measuring positions.

Therefore, even if the size of the area is increased, the number of metering cables can be increased so that the measurement can be performed under the same conditions regardless of the size of the area. Therefore, even in the case of a large area plasma source, the plasma uniformity can be easily adjusted.

4 is a graph showing light intensity for each measurement position before and after uniformity adjustment.

Referring to Figure 4, it can be seen that there is a deviation in the intensity of light for each measurement position before adjusting the uniformity. Therefore, the spatial deviation of the plasma uniformity was determined, and the impedance between the antennas was adjusted based on the spatial high frequency power distribution deviation of the plasma source antenna as a correction reference.

After analyzing the graph of measuring the light intensity for each measurement position after adjusting the uniformity, it can be seen that the spatial uniformity is improved as compared with the uniformity adjustment.

Therefore, by measuring the intensity of the plasma light indirectly outside the plasma chamber, even after fabricating the inductively coupled plasma generator, it is easy to measure and correct the deviation of the uniformity.

In addition, by tracking and analyzing a specific wavelength of a gas supplied to form a plasma when the light intensity deviation is extracted using a light quantity meter or a light spectrum analyzer, a distribution similar to the plasma distribution characteristic may be obtained.

In addition, the correction value may be extracted by mapping the process deviation obtained by actually performing the process and the data obtained through the plasma light wavelength spectrum analysis. Therefore, the correction operation may be performed by additionally including the plasma uniformity distortion caused by the parasitic parameter.

When fine-tuning the antenna of the inductively coupled plasma source with the spatial uniformity data of the light obtained through the present invention, its parameters can be adjusted by connecting an RLC series resonant circuit directly to the antenna.

Therefore, the spatial uniformity of the plasma by the overall inductively coupled plasma source can be adjusted to a desired level by adjusting the impedance difference of each antenna or the amount of high frequency current applied to each antenna.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the present invention is not limited to the disclosed exemplary embodiments, and various changes and modifications may be made by those skilled in the art without departing from the scope and spirit of the invention. Change is possible.

110: plasma antenna 120: dielectric window
130: plasma chamber 140: electrostatic chuck
150: substrate 160: plasma
170: process gas 180: high frequency power supply
190: high frequency matching device 200: vacuum pump
300: metering cable 400: optical switch
500: Light Meter

Claims (11)

A plurality of metering cables connected to an upper portion of a dielectric window that physically separates the plasma chamber and the plasma antenna in the inductively coupled plasma generator, and collects plasma light emitted from the plasma window through the dielectric window;
A light quantity meter connected to the plurality of photometric cables and receiving the collected plasma light into an electrical signal; And
Spatial uniformity measurement of an inductively coupled plasma source comprising an RLC series resonant circuit directly connected to the plasma antenna to adjust the impedance of the plasma antenna with spatial uniformity data of the plasma light obtained by using the converted electrical signal Device. The method of claim 1,
Connected to the plurality of photometric cables and the light meter,
And an optical switch disposed between the plurality of photometric cables and the light quantity meter. A plurality of metering cables connected to an upper portion of a dielectric window that physically separates the plasma chamber and the plasma antenna in the inductively coupled plasma generator, and collects plasma light emitted from the plasma window through the dielectric window;
An optical spectrum analyzer connected to the plurality of photometric cables and receiving the collected plasma light into an electrical signal; And
Spatial uniformity of the inductively coupled plasma source comprising an RLC series resonant circuit directly connected to the plasma antenna to adjust the impedance of the plasma antenna with spatial uniformity data of the plasma light obtained by using the electrical signal converted by the optical spectrum analyzer. Measuring device. The method of claim 3,
Connected to the plurality of photometric cables and the optical spectrum analyzer,
The apparatus of claim 1, further comprising an optical switch disposed between the plurality of photometric cables and the optical spectrum analyzer. The method according to claim 1 or 3,
Further comprising a light collecting lens connected to the metering cable,
The light collecting lens is a spatial uniformity measuring apparatus of the inductively coupled plasma source positioned between the dielectric window and the plurality of photometric cables. The method of claim 1,
The apparatus for measuring the uniformity of space of the inductively coupled plasma source includes an optical filter and an optical sensor. Generating an inductively coupled plasma gas in a plasma chamber of an inductively coupled plasma generator comprising a plasma chamber, a plasma antenna positioned above the plasma chamber, and a dielectric window that physically separates the plasma chamber from the plasma antenna; ;
Collecting the excited light from the generated plasma gas using a plurality of optical cables connected to an upper portion of the dielectric window of the inductively coupled plasma generator;
Measuring the intensity of the light collected using the optical cable using an optical quantity meter; And
And adjusting an impedance of the plasma antenna using an RLC series resonant circuit based on the measured intensity of light. The method of claim 7, wherein
Prior to the step of collecting the light,
A method of measuring spatial uniformity of an inductively coupled plasma source further comprising collecting light excited by the plasma gas using a light collecting lens. The method of claim 7, wherein
Before measuring the intensity of the light,
And switching the collected light using an optical switch. delete delete

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