JP3920209B2 - Plasma generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma generation apparatus for manufacturing a substrate such as a semiconductor by performing a deposition process or an etching process on a surface of a substrate to be processed using plasma. In particular, the present invention relates to a technique for manufacturing a large area substrate by generating plasma uniformly over a large area.
[0002]
[Prior art]
In recent years, attention has been paid to a polysilicon TFT-LCD capable of displaying an image with higher brightness than a TFT (thin film transistor) -LCD using an amorphous silicon film. In a polysilicon TFT-LCD, first, a polysilicon thin film is formed on a glass substrate to form a mother substrate. The mother substrate is divided into a number of two-dimensionally arranged pixel regions, and a thin film transistor (TFT) is formed in each pixel region to form an LCD substrate. In order to manufacture a large-screen polysilicon TFT-LCD, a polysilicon mother substrate having high quality, particularly high flatness is required.
[0003]
The polysilicon substrate is also attracting attention as a highly efficient solar cell substrate, and is required to have a large area as demand and application expand. In addition, as for a general semiconductor device substrate, a mother substrate obtained by deposition must be used for a large area exceeding the single crystal size.
[0004]
In order to manufacture a mother substrate used in these fields, a process using plasma is performed. The process using plasma includes a process of depositing a raw material of the mother substrate on the surface of the substrate to be processed which is a base, a process of etching the surface of the substrate to be processed including the mother substrate, and the like. Along with the increase in size of the substrate, it is necessary to increase the size of the apparatus for performing the plasma treatment. The biggest problem at that time is the nonuniformity of the plasma treatment. In order to solve this, it is necessary to make the plasma density as uniform as possible over the entire surface of the substrate. On the other hand, from the viewpoint of productivity, it is required to increase the plasma density, thereby increasing the deposition rate and the etching rate.
[0005]
As a method for generating plasma, there are an ECR (electron cycloton resonance) plasma method, a microwave plasma method, an inductively coupled plasma method, a capacitively coupled plasma method, and the like. Among them, the inductively coupled plasma method is a method in which a high frequency voltage is applied to an induction coil serving as an antenna, an induction electromagnetic field is generated inside the plasma generator, and plasma is thereby generated. According to this configuration, it is possible to generate high-density plasma, which is one of the requirements for the plasma apparatus. On the other hand, since the plasma density depends on the distance from the antenna, the plasma density uniformity, which is another requirement, is improved by devising the configuration of the antenna shape and position. . For example, Patent Document 1 describes that high frequency is introduced from a flat coil provided outside the ceiling of a plasma generation chamber to improve the uniformity of plasma density.
[0006]
[Patent Document 1]
JP 2000-58297 A ([0026] to [0027], FIG. 1)
[0007]
In order to increase the area of the substrate in such a configuration, the ceiling wall must be made sufficiently thick in order to ensure the mechanical strength of the plasma generation chamber ceiling. However, since the antenna is arranged outside the plasma generation chamber in the apparatus of Patent Document 1, the induction electromagnetic field radiated from the antenna is attenuated on the wall, and the strength of the induction electromagnetic field in the plasma generation chamber can be sufficiently obtained. Is difficult. That is, with the method described in Patent Document 1, it is difficult to make the plasma density sufficiently high, although a certain improvement is seen in the uniformity of the plasma density.
[0008]
On the other hand, the inventors of the present application have proposed to provide a high-frequency antenna in the plasma generation chamber ([0008] to [0010]) and further provide a plurality of antennas ([0050]). .
[0009]
[Patent Document 2]
Japanese Patent Laid-Open No. 2001-35697 ([0008] to [0010], [0050], FIG. 11)
[0010]
According to this configuration, since the wall of the plasma generation chamber does not become an obstacle, the induction electromagnetic field is radiated into the plasma generation chamber without attenuation, and the plasma density can be sufficiently increased. In addition, since the induction electromagnetic field is radiated from a plurality of antennas arranged evenly, the uniformity thereof can be improved, thereby improving the uniformity of the plasma density. Due to these effects, it is possible to perform a deposition process or an etching process on a substrate to be processed having a large area. Hereinafter, a configuration provided with a plurality of antennas described in Patent Document 2 is referred to as a “multi-antenna method”.
[0011]
[Problems to be solved by the invention]
In order to process a substrate having a larger area in the future, it is required to generate a plasma state with higher uniformity while ensuring a sufficient plasma density intensity. To that end, even in the multi-antenna method, it is necessary to examine parameters that are not currently considered, such as the shape and position of each antenna and the relationship between antennas.
[0012]
The present invention has been made to solve such problems, and an object of the present invention is to provide a plasma generation apparatus capable of generating a spatially uniform and high density plasma. is there.
[0013]
[Means for Solving the Problems]
A plasma generation apparatus according to the present invention, which has been made to solve the above problems,
a) a vacuum vessel;
b) a substrate base on which a substrate to be processed is placed, provided in the vacuum vessel;
c) three or more U-shaped high frequency antenna, a grounded and each radio-frequency antenna and the other parallel to the substrate table so as to surround said vacuum container with connecting one of the ends of the electrodes to a high frequency power supply a multi-antenna a multi-antenna, in which the adjacent electrodes of one or more sets of adjacent antennas of the same polarity arranged side by side on the inner wall surface of the vacuum container,
It is characterized by providing.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The plasma generation apparatus according to the present invention has a vacuum container whose inside is a plasma generation chamber. The vacuum vessel is connected to a vacuum pump, and the inside of the vacuum vessel is maintained at a predetermined degree of vacuum. A substrate stand on which the substrate to be processed is placed is provided inside the vacuum container. In addition, a gas introduction port is provided for introducing a gas as a raw material of the plasma to be generated into the vacuum vessel.
[0015]
A plurality of high-frequency antennas are provided in the vacuum vessel. When arranging the high-frequency antenna, the electrodes at both ends are arranged in parallel to the substrate table. One electrode of each high-frequency antenna is connected to a high-frequency power source, and the other electrode is grounded. An induction electromagnetic field is generated by applying a high-frequency voltage between these electrodes.
[0016]
The configuration so far is the same as the configuration described in Patent Document 2. In the present invention, adjacent electrodes of adjacent antennas have the same polarity. That is, both adjacent electrodes are connected to a high frequency power source or both are grounded.
[0017]
In order to explain the reason why the above configuration is used in the present invention, first, the polarity of the adjacent electrode of the adjacent antenna of the apparatus described in Patent Document 2 will be described. In FIG. 11 of Patent Document 2, the adjacent electrodes are connected to a high-frequency power source and ground so as to have different polarities. With such a configuration, a high frequency voltage is applied between the adjacent electrodes of the adjacent antenna, and the plasma density is locally increased only in that portion. For this reason, for example, the plasma density at a portion other than between the adjacent electrodes such as the central portion of the substrate base is lowered, and the uniformity of the plasma density is not good. If the installation density of the high-frequency antenna is increased to increase the plasma density and the distance between the adjacent antennas is reduced, the electric field generated between the adjacent electrodes of the adjacent antenna becomes stronger, and the uniformity of the plasma density is further deteriorated.
[0018]
On the other hand, in the present invention, since adjacent electrodes of adjacent antennas have the same polarity, the adjacent electrodes are always equipotential and no high frequency voltage is applied. Therefore, a local high plasma density region is not formed between the adjacent electrodes. The plasma density distribution can be controlled by appropriately selecting electrodes having the same polarity.
[0019]
Furthermore, by setting all the adjacent electrodes of all the high-frequency antennas to the same polarity, a voltage due to the difference in polarity does not occur between all the adjacent electrodes, and formation of a high plasma density region is prevented. Thereby, the fall of the plasma density of a board | substrate part can be prevented, and the uniformity of a plasma density can be improved over the inside in a vacuum vessel. In addition, since the distance between adjacent antennas can be reduced and the installation density of the high-frequency antenna can be increased without deteriorating the uniformity of the plasma density, the plasma density can be increased as a whole.
[0020]
【The invention's effect】
According to the present invention, in a multi-antenna type inductively coupled plasma generating apparatus capable of manufacturing a large area substrate, the plasma density of the substrate portion can be further increased and the plasma density distribution can be made more uniform. Further, the installation density of the high-frequency antenna can be increased as compared with the prior art, and higher density plasma can be generated. By using this plasma generation apparatus, it is possible to perform deposition processing or etching processing on a large area substrate to be processed with high uniformity and at a high speed, and to manufacture a substrate having high uniformity over the entire surface. it can. Further, depending on the method of use, the plasma density distribution can be controlled.
[0021]
【Example】
1 and 2 show the configuration of an embodiment of the plasma generating apparatus according to the present invention. 1 is a vertical sectional view, and FIG. 2 is a plan view. The inside of the vacuum vessel 11 becomes a plasma generation chamber of the present plasma generation apparatus. The horizontal cross section inside the vacuum vessel 11 is a rectangle having a long side of 130 cm and a short side of 100 cm. A vacuum pump (not shown) is connected to the vacuum vessel 11. A rectangular planar substrate table 14 having a long side of 94 cm and a short side of 76 cm for mounting the substrate to be processed 13 in the vacuum vessel 11 is provided. The substrate table 14 can be moved up and down by a lifting unit 141 provided in the lower part thereof. In addition, a substrate inlet / outlet 12 is provided on the lower side of the vacuum vessel 11 for taking in and out the substrate 13 to be processed. In the upper part of the vacuum vessel 11, there is provided a gas pipe 15 including a circulating portion that circulates around the vacuum vessel 11 horizontally along the inner wall and a connection portion connected to the outside of the vacuum vessel 11. A large number of holes are arranged on the surface of the circulating portion of the gas pipe 15 in an appropriate distribution in order to introduce gas evenly into the vacuum vessel 11.
[0022]
Among the four side walls of the vacuum vessel 11, four high frequency antennas 16 are provided at equal intervals on each of the two longer surfaces in the horizontal direction and three on the shorter two surfaces. The height of the high frequency antenna 16 from the substrate table 14 is 18 cm. Hereinafter, three or four high-frequency antennas provided on the same side wall will be described as a set of antenna groups. FIG. 2 shows an antenna group 191 composed of three high-frequency antennas and an antenna group 192 composed of four high-frequency antennas as examples of the antenna group. The shape of each high frequency antenna 16 is U-shaped. In the high-frequency antenna of this embodiment, the length of the side in the direction parallel to the side wall is 15 cm. The gap between adjacent high frequency antennas in the same antenna group is set to 8.0 cm on the longer side wall in the horizontal direction and 9.5 cm on the shorter side wall. The number, size, and interval of these high-frequency antennas are appropriately set according to the shape and area of the substrate to be manufactured and the shape and cross-sectional area of the horizontal section inside the vacuum vessel 11.
[0023]
One high frequency power supply 18 is provided for each antenna group. One of the two electrodes of each high-frequency antenna 16 is connected to the high-frequency power source 18 via the impedance matching unit 17 and the other is grounded. In the same antenna group, adjacent electrodes have the same polarity in adjacent high frequency antennas. For example, in the antenna group 191, in the adjacent high-frequency antenna 161 and the high-frequency antenna 162, the electrodes adjacent to each other are both connected to the impedance matching unit 17-the high-frequency power source 18, and the high-frequency antenna 162 and the high-frequency antenna 163 are adjacent to each other. Are grounded together.
[0024]
The operation of the plasma generating apparatus of this embodiment will be described. The raising / lowering unit 141 is operated to lower the substrate table 14. The substrate 13 to be processed is put into the vacuum container 11 from the substrate entrance 12 and placed on the substrate table 14, and then the substrate table 14 is raised to a predetermined position. A plasma source gas is introduced into the gas pipe 15 at a predetermined gas pressure, and predetermined high-frequency power is supplied to each high-frequency antenna 16 from four high-frequency power sources 18. Thereby, each high frequency antenna 16 produces | generates an induction electric field.
[0025]
By setting the adjacent electrodes of the adjacent antennas to have the same polarity, no potential difference is generated between these electrodes in the gap 20 between the adjacent antennas shown in FIG. For this reason, it is possible to prevent the plasma concentration from increasing due to the presence of the potential difference between the terminals in the gap 20 and to prevent the plasma concentration from decreasing in other portions. Thereby, the uniformity of the spatial distribution of the plasma concentration can be further improved.
[0026]
Due to this highly uniform induced electric field, the gas introduced into the vacuum vessel 11 is ionized to generate plasma with high spatial distribution. By this plasma, a highly uniform deposition process or etching process can be performed over the entire surface of the substrate 13 having a large area.
[0027]
FIG. 4 shows a plan view of a plasma generating apparatus which is a comparative example with respect to the present embodiment. In this comparative example, terminals adjacent to each other in adjacent high-frequency antennas have opposite polarities. For example, in the adjacent high-frequency antenna 161 and high-frequency antenna 162, the terminal close to the high-frequency antenna 162 is connected to the ground side in the high-frequency antenna 161, and the terminal close to the high-frequency antenna 161 is connected to the impedance matcher 17- Connected to a high frequency power supply 18. Except for the polarity of the terminals, the configuration is the same as that of the present embodiment of FIG.
[0028]
In this comparative example, as shown in FIG. 3B, a potential difference is generated between the electrodes in the gap 20. For this reason, the plasma concentration in the gap 20 becomes higher than other positions. In addition, the plasma concentration at other positions decreases accordingly.
[0029]
Below, the result of having measured the density of the plasma produced | generated in the plasma production apparatus of the said Example is shown. In addition, the density of plasma generated in the plasma generation apparatus of the comparative example is shown and compared with the present embodiment. The plasma generation conditions in this measurement are as follows. The generated plasma is Ar plasma. The inside of the vacuum vessel 11 is evacuated to 5 × 10 ⁻⁵ Pa in advance, and then Ar gas as a raw material gas is supplied to a gas pressure of 1.33 Pa. High frequency power having a frequency of 13.56 MHz is supplied to each high frequency antenna 16. Other conditions are shown in the description of each measurement. The Langmuir probe method was used to measure the plasma density.
[0030]
FIG. 5 shows the result of measuring the plasma density at the same height as the high-frequency antenna and directly above the center of the substrate table. Here, the vertical axis represents the plasma electron density expressed in a logarithmic scale, and the horizontal axis represents the magnitude of the high-frequency power supplied from each high-frequency power source. Regardless of the value of the high-frequency power, the apparatus of this embodiment can obtain a higher plasma density than the apparatus of the comparative example. In particular, when the high-frequency power is 1200 W to 2500 W, the plasma density of this example is about twice that of the comparative example.
[0031]
FIG. 6 shows the result of measuring the spatial distribution of plasma density. The measurement conditions at that time are as follows. The high frequency power is supplied only to a set of antenna groups 192 shown in FIGS. The magnitude of the high frequency power supplied from the high frequency power supply is 1500W. The horizontal axis of FIG. 6 which is a measurement point of the plasma density represents a position on a straight line 13 cm away from the side wall provided with the antenna group 192 in parallel.
[0032]
As shown in FIG. 6, in the plasma generating apparatus of the comparative example, the plasma density at the end is lower than the plasma density near the center, and the spatial distribution of the plasma density is biased. On the other hand, in the plasma generation apparatus of the present embodiment, the deviation of the spatial distribution of the plasma density is smaller than that in the plasma generation apparatus of the comparative example, and the uniformity of the plasma density distribution is improved.
[Brief description of the drawings]
FIG. 1 is a vertical sectional view of an embodiment of a plasma generating apparatus according to the present invention.
FIG. 2 is a plan view of the plasma generation apparatus of FIG.
FIG. 3 is an explanatory diagram of a gap between adjacent antennas and a potential difference therebetween.
FIG. 4 is a plan view of a plasma generation apparatus of a comparative example.
5 is a graph showing the plasma density at the center of the apparatus in the plasma generation apparatus of the present invention in FIG. 2 and the plasma generation apparatus in the comparative example in FIG. 4;
6 is a graph showing a plasma density spatial distribution in the plasma generation apparatus of the present invention of FIG. 2 and the plasma generation apparatus of the comparative example of FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Vacuum container 12 ... Substrate carrying in / out port 13 ... Processed substrate 14 ... Substrate stand 141 ... Elevating part 15 ... Gas pipe 16, 161, 162, 163 ... High frequency antenna 17 ... Impedance matching device 18 ... High frequency power supply 191, 192 ... Antenna group 20 ... Gap

Claims (5)

a) a vacuum vessel;
b) a substrate base on which a substrate to be processed is placed, provided in the vacuum vessel;
c) three or more U-shaped high frequency antenna, a grounded and each radio-frequency antenna and the other parallel to the substrate table so as to surround said vacuum container with connecting one of the ends of the electrodes to a high frequency power supply a multi-antenna wherein a multi-antenna provided side by side on the inner wall surface of the vacuum chamber, where the adjacent electrodes of one or more sets of adjacent antennas of said high frequency antenna to the same polarity,
A plasma generating apparatus comprising:   The plasma generating apparatus according to claim 1, wherein adjacent electrodes of adjacent antennas have the same polarity in all high-frequency antennas. In the vacuum vessel, three or more U- shaped high-frequency antennas , one of the electrodes at both ends thereof is connected to a high-frequency power source, the other is grounded, and each high-frequency antenna is parallel to the substrate table and is placed in the vacuum vessel. In a substrate manufacturing method using a plasma generating apparatus provided with a multi-antenna arranged side by side on an inner wall surface of the vacuum vessel so as to surround, the adjacent electrodes of one set or a plurality of sets of adjacent antennas of the high-frequency antenna have the same polarity By doing so, the plasma density distribution in the said plasma production | generation apparatus is controlled, The board | substrate manufacturing method characterized by the above-mentioned.   4. The substrate manufacturing method according to claim 3, wherein adjacent electrodes of adjacent antennas have the same polarity in all high-frequency antennas. In the vacuum vessel, three or more U- shaped high-frequency antennas , one of the electrodes at both ends thereof is connected to a high-frequency power source, the other is grounded, and each high-frequency antenna is parallel to the substrate table and is placed in the vacuum vessel. In the plasma generating apparatus including a multi-antenna arranged side by side on the inner wall surface of the vacuum vessel so as to surround , the plasma is obtained by setting adjacent electrodes of one or more sets of adjacent antennas of the high-frequency antenna to the same polarity. A plasma control method for controlling a plasma density distribution in a generation apparatus.

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