JP2004111334A - Plasma treating apparatus and plasma treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treating apparatus and a plasma treatment method for adjusting magnetic field strength and etching rate. <P>SOLUTION: In the plasma treating apparatus, a pair of electrodes is arranged in a treatment chamber that can be maintained in vacuum, either electrode is allowed to support a body to be treated, plasma is generated between the electrodes, a magnetic field is formed on a surface to be treated in the body to be treated by a magnetic field forming means, and the body to be treated is subjected to specific plasma treatment. The magnetic field formed by the magnetic field forming means is nearly in parallel with a surface to be treated at the center of the body to be treated, the magnetic field forming means is composed so that two annular magnets formed by annularly installing a plurality of segment magnets having a magnetization angle at least in an annular direction oppose each other via the surface to be treated, and the magnetization angles in the annular direction of at least the pair of opposing segment magnets in the segment magnets that oppose via the surface to be treated are allowed to differ each other. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plasma processing apparatus and a plasma processing method, and more particularly to a plasma processing apparatus and a plasma processing apparatus for performing a predetermined plasma process on a target object while forming a magnetic field on a target surface in the target object in a processing chamber. Regarding the processing method.
[0002]
[Prior art]
2. Description of the Related Art A magnetron plasma apparatus has been conventionally used for performing plasma processing such as sputtering and etching. In such a magnetron plasma apparatus, a magnetic field forming means is disposed outside a processing chamber, and the formed magnetic field is applied horizontally to an object to be processed, for example, a semiconductor wafer (hereinafter, referred to as a “wafer”) in the processing chamber. At the same time, a high-frequency electric field orthogonal to the processing surface of the wafer is applied, and plasma processing such as etching is performed with extremely high efficiency by utilizing the drift motion of electrons generated at that time.
[0003]
In the magnetron plasma, the magnetic field perpendicular to the electric field contributes to the electron drift motion, that is, the magnetic field horizontal to the surface to be processed of the wafer. To improve the plasma uniformity, a uniform horizontal magnetic field is formed. Wanted to be.
[0004]
A dipole ring magnet is known as a magnetic field forming means capable of generating such a desired magnetic field. As shown in FIG. 21, the dipole ring magnet 10 has a plurality of columnar anisotropic segment magnets 14 arranged outside the processing chamber 12 in a ring shape, and the magnetization directions of the plurality of segment magnets 14 are slightly changed. The horizontal magnetic field B is formed uniformly by changing the horizontal magnetic field B as a whole. FIG. 21 is a view (plan view) of the magnetron plasma apparatus as viewed from above, in which the base end side in the magnetic field direction is N, the front end side is S, and positions 90 ° from these are indicated by E and W. . In FIG. 21, reference numeral 20 denotes a wafer. Arrows drawn in the anisotropic segment magnet 14 indicate the magnetization direction of the anisotropic segment magnet 14. When each of the anisotropic segment magnets 14 is arranged in the direction of magnetization as shown, a magnetic field B in the direction indicated by the arrow is generated in the ring.
[0005]
By the way, in the above-mentioned dipole ring magnet 10, although the uniformity of the magnetic field is remarkably improved as compared with the conventional magnetic field forming means, the horizontal magnetic field B formed by the dipole ring magnet 10 is shown in FIG. In this state, the electrons move in one direction due to drift motion because the electrons are directed only in one direction from N to S in 21. As a result, the plasma density becomes non-uniform, and charge-up occurs when holes are formed by etching. May cause damage. Therefore, in order to change the direction of the drift motion of the electrons, it is necessary to rotate the dipole ring magnet 10 along its circumferential direction or to use a high-frequency power source as an applied power source to make the plasma density uniform. (For example, see Patent Document 1).
[0006]
However, the magnetic field forming means using the dipole ring magnet 10 solves the problem that the processing shape differs between the central portion and the peripheral portion, particularly, the edge portion of the wafer due to the non-uniformity of the plasma, for example, due to the difference in ion energy. Did not reach.
[0007]
In addition, there is a problem that the magnetic field intensity near the wafer edge becomes too strong as compared with the central portion of the wafer, and the plasma density in such a portion becomes high.
[0008]
To solve the above problem, Japanese Patent Application Laid-Open No. 7-288195 (hereinafter referred to as Patent Document 2) discloses that a dipole ring magnet is divided into two parts when a magnetic field strength gradient is provided in the EW direction. There is described a method of adjusting the magnetic field intensity ratio between the center and the end of the wafer (around the magnet) by adjusting the size of the gap of the dipole ring magnet.
[0009]
Patent Document 2 also discloses a method in which a convex downward magnetic field line of a magnetic field passes through a surface to be processed of a wafer, and finely adjusts a magnetic field distribution by moving the entire dipole ring magnet up and down. I have.
[0010]
[Patent Document 1]
JP-A-7-169591
[Patent Document 2]
JP-A-7-288195
[0011]
[Problems to be solved by the invention]
However, although the dipole ring magnet divided into two can certainly adjust the magnetic field strength ratio and the magnetic field direction between the center and the edge of the wafer, one dipole ring magnet can be adjusted with respect to the other dipole ring magnet. The magnet remains fixed. For this reason, in the dipole ring magnet, since the magnetization directions between the opposing segment magnets are all the same, the strength of the formed magnetic field and the controllability of the direction of the magnetic field are constant and low.
[0012]
In addition, during etching, it is not sufficient to solve the non-uniformity in the wafer surface due to a higher etching rate at the edge of the wafer than at the center of the wafer.
[0013]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the conventional plasma processing apparatus, and an object of the present invention is to control the strength of a magnetic field and the angle of a line of magnetic force used during predetermined plasma processing such as etching. It is an object of the present invention to provide a new and improved plasma processing apparatus and method capable of performing the above-mentioned processes.
[0014]
In particular, it is an object of the present invention to provide a new and improved plasma processing apparatus and a plasma processing method capable of adjusting an etching rate of a central portion of a wafer and a peripheral portion of the wafer during etching to improve the uniformity of the etching rate.
[0015]
[Means for Solving the Problems]
In order to solve the above problems, according to a first aspect of the present invention, a pair of electrodes are arranged in a processing chamber that can be maintained in a vacuum, and one of the electrodes supports a target object, and the electrode is placed between the electrodes. In a plasma processing apparatus that generates plasma and forms a magnetic field on a surface to be processed of a processing object by a magnetic field forming means and performs predetermined plasma processing on the processing object, the magnetic field formed by the magnetic field forming means is At the center of the processing body, the magnetic field forming means is substantially parallel to the surface to be processed, and the magnetic field forming means includes two annular magnets formed by arranging a plurality of segment magnets having at least annular magnetization angles in a ring shape. The magnetizing angle of at least one pair of the segment magnets facing each other through the surface to be processed in the annular direction. And wherein varying the other, the plasma processing apparatus is provided.
[0016]
At this time, the magnetization directions of the segment magnets installed on the two ring magnets are all the same, and the other ring magnet is shifted in the ring direction with respect to one ring magnet, so that the segment magnets facing each other are magnetized. The magnetization angles in the annular directions may be different from each other.
[0017]
According to a second aspect of the present invention, a pair of electrodes are arranged in a processing chamber capable of maintaining a vacuum, and one or both of the electrodes support a target object. And a plasma processing method for generating a plasma between the electrodes, forming a magnetic field on the surface of the object to be processed by the magnetic field forming means, and performing predetermined plasma processing on the object to be processed. The magnetic field is substantially parallel to the surface to be processed at the central portion of the object to be processed, and the magnetic field forming means includes two annular magnets formed by arranging a plurality of segment magnets having at least annular magnetization angles in an annular shape. Are arranged so as to face each other via the surface to be processed, and the annular direction of at least a pair of segment magnets among the segment magnets facing each other via the surface to be processed Characterized by the plasma treatment by the magnetic field formed with different magnetization angles, plasma processing method is provided.
[0018]
At this time, the magnetization directions of the segment magnets installed on the two ring magnets are all the same, and the other ring magnet is shifted in the ring direction with respect to one ring magnet, so that the segment magnets facing each other are magnetized. The plasma processing may be performed using a magnetic field formed by making the magnetization angles in the annular direction different from each other.
[0019]
With this configuration, the magnetic field between the segment magnets facing each other is weakened or strengthened, so that the magnetic field formed at the center and the end of the surface of the object to be processed is reduced. The intensity can be adjusted, and the uniformity of the object to be processed in the predetermined plasma processing can be improved.
[0020]
When the plasma processing is etching, if the magnetization directions of the ring magnets of the segment magnets provided on the two ring magnets are all the same, etching at the end of the object to be processed is performed. When the rate is reduced, the etching rate is controlled by, for example, making the rotation angle of one annular magnet in the annular direction relative to one annular magnet close to 180 degrees in accordance with the reduction rate of the etching rate. Further, when increasing the etching rate at the end of the object to be processed, for example, by making the rotation angle of one annular magnet in the annular direction relative to one annular magnet close to 0 degrees in accordance with the increase in the etching rate. Control the etching rate.
[0021]
With this configuration, the etching rate can be flexibly controlled according to the change in the etching rate.
[0022]
Further, at this time, at least one of the two annular magnets is moved in the vertical direction with respect to the surface to be processed of the object to be processed to adjust the magnetic field angle at the end of the object to be processed. Thereby, the etching rate at the end of the object to be processed can be adjusted.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted.
[0024]
FIG. 1 is a sectional view showing a plasma processing apparatus according to the first embodiment of the present invention. The plasma processing apparatus 100 has a processing chamber 102 that is configured to be airtight. The processing chamber 102 has a stepped cylindrical shape including a small-diameter upper portion 102a and a large-diameter lower portion 102b. The wall of the processing chamber 102 is made of, for example, aluminum and is grounded.
[0025]
In the processing chamber 102, a support table 104 for horizontally supporting a semiconductor wafer 300 having a diameter of, for example, 300 mm (hereinafter, referred to as a “wafer”) is provided as an object to be processed. The support table 104 is made of, for example, aluminum, and is supported by a conductor support 108 via an insulating plate 106. A focus ring 110 made of a conductive material, for example, single-crystal silicon is provided on the outer periphery above the support table 104.
[0026]
The support table 104 and the support table 108 can be moved up and down by a ball screw mechanism including a ball screw 112, and a drive portion below the support table 108 is covered with a bellows 114 made of stainless steel (SUS) or the like. ing. A bellows cover 116 is provided outside the bellows 114.
[0027]
An RF power supply 120 is connected to the support table 104 via a matching box 118, and forms a lower electrode. The RF power supply 120 supplies, for example, 13.56 MHz high frequency power to the support table 104. On the other hand, a shower head 122, which will be described later, constituting an upper electrode is provided in parallel with and opposed to the support table 104, and the shower head 122 is grounded. In the plasma processing apparatus of the present embodiment, the support table (lower electrode) 104 and the shower head (upper electrode) 122 function as a pair of electrodes.
[0028]
An electrostatic chuck 124 for electrostatically attracting the wafer 300 is provided on the surface of the support table 104. The electrostatic chuck 124 has an electrode 124a interposed between insulators 124b, and a power source 126 is connected to the electrode 124a. When a voltage is applied to the electrode 124a from the power supply 126, the wafer 300 is attracted by Coulomb force.
[0029]
A coolant channel (not shown) is formed in the inside of the support table 104, and the temperature of the support table 104 is controlled by circulating an appropriate coolant in the coolant channel. A supply system (not shown) is provided, and by supplying an inert gas such as helium, the thermal conductivity between the support table 104 and the wafer 300 can be increased to control the wafer 300 at a predetermined temperature. It has become. A baffle plate 128 is provided outside the focus ring 110. The baffle plate 128 communicates with the processing chamber 102 through the support table 108 and the bellows 114.
[0030]
A shower head 122 is provided on a top wall portion of the processing chamber 102 so as to face the support table 104. The shower head 122 is provided with a number of gas discharge holes 130 on the lower surface thereof, and has a gas inlet 132 on the upper portion thereof. A space portion 134 is formed inside the shower head 122. A gas supply pipe 136 is connected to the gas introduction unit 132, and the other end of the gas supply pipe 136 is supplied with a processing gas composed of a reaction gas for plasma processing such as etching and a processing gas composed of a dilution gas. System 138 is connected. As the reaction gas, for example, a halogen-based gas, and as the diluting gas, for example, a gas usually used in this field, such as an Ar gas or a He gas, can be used.
[0031]
The processing gas as described above reaches the space 134 of the shower head 122 from the processing gas supply system 138 via the gas supply pipe 136 and the gas introduction unit 132, is discharged from the gas discharge holes 130, and is formed on the wafer 300. The etched film is etched.
[0032]
An exhaust port 140 is formed on a side wall of the lower portion 102b of the processing chamber 102, and an exhaust system 142 is connected to the exhaust port 140. By operating a vacuum pump (not shown) provided in the exhaust system 142, the pressure inside the processing chamber 102 can be reduced to a predetermined degree of vacuum. On the other hand, a gate valve 144 for opening and closing the loading / unloading port of the wafer 300 is provided above the side wall of the lower portion 102 b of the processing chamber 102.
[0033]
On the other hand, a dipole ring magnet 200 is arranged concentrically around the upper part 102a of the processing chamber 102 as a magnetic field generating means, and applies a magnetic field to a space between the support table 104 and the shower head 122. ing. The dipole ring magnet 200 is rotatable by rotating means (not shown) such as a motor.
[0034]
In the plasma processing apparatus configured as described above, first, the gate valve 144 is opened, the wafer 300 is loaded into the processing chamber 102, and is placed on the support table 104. Then, the support table 104 is raised to the position shown in the drawing. The inside of the processing chamber 102 is evacuated through an exhaust port 140 by a vacuum pump of an exhaust system 142.
[0035]
After the inside of the processing chamber 102 reaches a predetermined degree of vacuum, a predetermined processing gas is introduced from the processing gas supply system 138 into the processing chamber 102, and the inside of the processing chamber 102 is maintained at a predetermined pressure, for example, 40 mTorr. In this state, high-frequency power having a frequency of, for example, 13.56 MHz and a power of, for example, 1000 to 5000 W is supplied from the RF power supply 120 to the support table 104. At this time, a predetermined voltage is applied from the DC power supply 126 to the electrode 124a of the electrostatic chuck 124, and the wafer 300 is attracted by Coulomb force.
[0036]
In this case, by applying high-frequency power to the support table 104 as the lower electrode as described above, an electric field is formed between the shower head 122 as the upper electrode and the support table 104 as the lower electrode. You. On the other hand, since a horizontal magnetic field is formed by the dipole ring magnet 200 in the upper portion 102a of the processing chamber 102, a magnetron discharge is generated due to the drift of electrons in the processing space where the wafer 300 is present, and the processing gas formed thereby is formed. The predetermined film formed on the wafer 300 is etched by the plasma.
[0037]
Next, the dipole ring magnet 200 used as the magnetic field forming means in the present embodiment will be described. FIG. 2 is a plan view schematically showing a state in which the dipole ring magnet placed around the processing chamber 102 is viewed from above.
[0038]
As shown in FIG. 2, the dipole ring magnet 200 of the present embodiment is an annular magnet configured by mounting a plurality of column-shaped anisotropic segment magnets 202 on a ring-shaped magnetic material casing 204. In the present embodiment, 32 columnar anisotropic segment magnets 202 are arranged at equal intervals in a ring shape. However, the number of the anisotropic segment magnets 202 is not limited to this example, and the cross-sectional shape is not limited to a circle as in this example, but may be an arbitrary shape such as a square, a rectangle, or a trapezoid. Can be. The magnet material that constitutes the anisotropic segment magnet 202 is not particularly limited, and various known magnet materials such as a rare earth magnet, a ferrite magnet, and an Alnico (registered trademark) magnet can be used.
[0039]
In FIG. 2, arrows shown in the anisotropic segment magnets 202 indicate the directions of magnetization, and the dipole ring magnet 200 of this embodiment changes the magnetization directions of the plurality of anisotropic segment magnets 202 little by little. Thus, a horizontal magnetic field B directed in one direction as a whole is formed. In FIG. 2, the base end side in the magnetic field direction is indicated by N, the front end side is indicated by S, and positions 90 ° from these are indicated by E and W.
[0040]
As shown in FIG. 2, an electric field EL is formed on the upper surface of the semiconductor wafer 300, while a magnetic field B is formed in the processing chamber 102 substantially in one direction from N to S. Accordingly, the generated electrons travel by drifting from E to W. For this reason, the electron density on the W side is increased in this state, causing non-uniform plasma density. Therefore, in the present embodiment, in order to change the direction of the drift motion of the electrons, the dipole ring magnet 200 is rotated along the circumferential direction of the processing chamber 102 by rotating means (not shown) such as a motor. Solve a problem.
[0041]
FIG. 3 is a perspective view schematically showing the dipole ring magnet 200. FIG. The dipole ring magnet 200 of the present embodiment includes two annular magnets, an upper dipole ring magnet 200a and a lower dipole ring magnet 200b, which are arranged above and below the wafer processing surface. The arrangement and magnetization direction of each anisotropic segment magnet 202 in each dipole ring magnet 200a, 200b are the same, as shown in FIG.
[0042]
In this embodiment, the lower dipole ring magnet 200b is shifted in the annular direction with respect to the upper dipole ring magnet 200a, so that the anisotropic segment magnets 202 facing each other have different magnetization angles in the annular direction. In this embodiment, the lower dipole ring magnet 200b is shifted in the annular direction with respect to the upper dipole ring magnet 200a. However, the upper dipole ring magnet 200a is shifted in the annular direction with respect to the lower dipole ring magnet 200b. Is also possible.
[0043]
FIG. 4 is an operation explanatory diagram of the present embodiment. In FIG. 4, the arrows indicate the directions of the magnetic fields formed on the dipole ring magnets 200a and 200b. (A) shows the direction of the magnetic field formed on each dipole ring magnet 200a, 200b when the lower dipole ring magnet 200b is not displaced in the annular direction with respect to the upper dipole ring magnet 200a, and (b), (c) ), (D), and (e) show the cases where the angles θ at which the lower dipole ring magnet 200b is shifted in the annular direction with respect to the upper dipole ring magnet 200a are 45 °, 90 °, 135 °, and 180 °, respectively. The direction of the magnetic field formed in the dipole ring magnets 200a and 200b is shown.
[0044]
FIG. 5 is a diagram showing the arrangement of the anisotropic segment magnets 202 of each dipole ring magnet 200a, 200b in the operation of the present embodiment. The dotted line between AA ′ in FIG. 5 is a reference line when the lower dipole ring magnet 200b is shifted in the annular direction with respect to the upper dipole ring magnet 200a shown in FIG. 3, and the W side in FIG. Is indicated by 5, the anisotropic segment magnets 202 located on the left side of the EW axis in FIG. 2 are sequentially moved from point A to 1L, 2L,. 16L, and the anisotropic segment magnets 202 on the right side of the EW axis are sequentially described as 1R, 2R,.
[0045]
As shown in FIG. 4, by displacing the lower dipole ring magnet 200b in the annular direction, for example, by 45 ° with respect to the upper dipole ring magnet 200a, the anisotropy of the arrangement 2L, 1L, 1R, 2R in the upper dipole ring magnet 200a. The anisotropic segment magnets 202 in the lower dipole ring magnet 200b facing the anisotropic segment magnets 202 change from the arrangements 2L, 1L, 1R, and 2R to the anisotropic segment magnets 202 in the arrangements 3R, 4R, 5R, and 6R, respectively. Thereby, the magnetic field directions of the anisotropic segment magnets 202 facing vertically are different from each other.
[0046]
In the present embodiment, since the arrangement and the magnetization direction of the anisotropic segment magnets 202 in the upper dipole ring magnet 200a and the lower dipole ring magnet 200b are similar to each other, the two dipole ring magnets 200a and 200b are shifted. When the angle θ is 0 °, the magnetic field strength in the NS direction near the center of the wafer is strengthened. However, as the shifted angle θ is increased, the magnetic field strength in the NS direction near the center of the wafer is gradually increased. Become weak. When the shifted angle θ reaches 180 °, since the anisotropic segment magnets 202 in the upper dipole ring magnet 200a and the lower dipole ring magnet 200b are opposite to each other, the NS direction near the center of the wafer is changed. The magnetic field strengths at will be weakest each other.
[0047]
The analysis results of the magnetic field strength and the Bz degree representing the magnetic field angle in the vertical direction with respect to the surface to be processed in the above operation are specifically shown in the following graphs. Changes in the magnetic field strength when the lower dipole ring magnet 200b is shifted in the annular direction with respect to the upper dipole ring magnet 200a are shown when the shifted angles θ are 0 °, 45 °, 90 °, 135 °, and 180 °, respectively. Indicated at 6, 7, 8, 9 and 10. In each of the above figures, (a) is a graph showing a change in magnetic field strength (unit: G) and a Bz degree (unit: °) representing a magnetic field angle in a direction perpendicular to the surface to be processed, and (b) is a graph showing magnetic field strength. It is a table | surface which shows the change of intensity | strength and Bz degree showing the magnetic field angle of the perpendicular direction with respect to a to-be-processed surface. In the graph of (a), the left vertical axis represents the magnetic field intensity, the right vertical axis represents the Bz degree, and the horizontal axis represents the distance (mm) from the wafer center point. Further, the X axis, the Y axis, and the XY axes indicate the coordinate directions shown in FIG.
[0048]
From the graphs in the above figures, as the angle θ when the lower dipole ring magnet 200b is shifted in the annular direction with respect to the upper dipole ring magnet 200a increases from 0 ° to 180 °, the magnetic field intensity at the central portion of the wafer decreases. You can see that it has become. In addition, the magnetic field intensity in the wafer region (up to about ± 150 mm from the center point) is also incidentally reduced.
[0049]
Also, it can be seen that the Bz degree representing the magnetic field angle in the vertical direction with respect to the surface to be processed also changes as the lower dipole ring magnet 200b is shifted in the annular direction with respect to the upper dipole ring magnet 200a. In particular, there is a tendency for the Bz degree to fluctuate greatly at a point distant from the center of the wafer.
[0050]
Using the magnetic field forming means of the present embodiment, a silicon thermal oxide film formed on a wafer having a diameter of 300 mm as an object to be processed is plasma-etched. The plasma etching conditions at this time include, for example, a condition in which the pressure in the processing chamber is 40 mT, and the high-frequency power 4000 W applied to the lower electrode is applied for 1 minute. ₄ F ₈ , CO, Ar, O ₂ Is supplied as a processing gas at a flow rate ratio of 20 sccm / 100 sccm / 400 sccm / 10 sccm, and the temperatures of the upper electrode, the processing chamber side wall, and the lower electrode are respectively 60 ° C., 60 ° C., 10 ° C., and the backside gas (He). The pressure is set to 10 Torr at the center of the object and 50 Torr at the periphery. Note that the positional relationship between the upper and lower two dipole ring magnets 200a and 200b and the wafer 300 is such that when the shift angle θ is 0 °, the magnetic field intensity at the center of the wafer 300 is 120 Gauss, and the magnetic field angle at the edge of the wafer 300 is Bz is set to 4.93 degrees. FIG. 11 is a graph showing the analysis result of the etching rate when the plasma etching process is performed under such conditions.
[0051]
FIG. 11 shows a change in the etching rate with respect to the distance from the center of the wafer in the X-axis and Y-axis directions in FIG. 2, the vertical axis represents the etching rate (unit: nm / min), and the horizontal axis represents the wafer center point. Represents the distance (unit: mm) from. (A), (b), (c), (d), and (e) show that the angles θ at which the lower dipole ring magnet 200b is displaced in the annular direction with respect to the upper dipole ring magnet 200a are 0 ° and 45 °, respectively. , 90 °, 135 °, and 180 ° indicate changes in the etching rate with respect to the distance from the center of the wafer.
[0052]
According to the above figure, as the angle θ at which the two upper and lower dipole ring magnets 202 are shifted increases, the etching rate at the center and the periphery of the wafer fluctuates. In particular, the etching rate at the edge of the wafer depends on the dipole ring magnet 202. It can be seen that the shift angle θ is increased and falls as the angle approaches 180 °. This makes it possible to flexibly control the etching rate in accordance with the change in the etching rate, and increases the etching rate at the peripheral portion of the wafer, which has been a problem in the conventional etching processing, so that the in-plane surface of the wafer during etching is increased. It can be expected that the non-uniformity will be eliminated.
[0053]
Next, FIGS. 12 to 20 show experimental results when the type of film formed on the wafer and the vertical magnetic field angle at the edge of the wafer were changed.
[0054]
Each of the above figures shows the change in the etching rate with respect to the distance from the wafer center in the X-axis and Y-axis directions in FIG. 2, the vertical axis represents the etching rate (unit: nm / min), and the horizontal axis represents the wafer center point. Represents the distance (unit: mm) from. The equations described in the graphs in the above figures show the average value (unit: nm / min) of the etching rate from the edge of the wafer to the edge and the rate of variation (in-plane uniformity) (%). It is a measure of the uniformity of the etching rate. 12 (a), 20 (b), and 20 (c), the angles θ at which the lower dipole ring magnet 200b is displaced in the annular direction with respect to the upper dipole ring magnet 200a are 0 °, 90 °, and 180 °, respectively. The change of the etching rate with respect to the distance from the wafer center in the case of °
[0055]
12 to 14 show the case where the surface to be processed of the wafer is a silicon nitride film, FIGS. 15 to 17 show the case where the surface to be processed of the wafer is a thermal oxide film, and FIGS. This is the case where the processed surface of the wafer is a resist. 12, 15, and 18 show the case where the Bz degree is 4.93, and FIGS. 13, 16, and 19 show that the positional relationship between each dipole ring magnet 200a, 200b and the wafer 300 is changed. When the Bz degree is 8.53 with the magnetic field intensity at the center of 300 kept at 120 Gauss, FIGS. 14, 17 and 20 similarly show the change in the etching rate when the Bz degree is 12.88. .
[0056]
The conditions of the plasma etching process in this experiment are, for example, CHF under the condition that the pressure in the processing chamber is 175 mT and the high-frequency power 1000 W applied to the lower electrode is applied for 1 minute. ₃ , CF ₄ , Ar, O ₂ Is supplied as a processing gas at a flow rate ratio of 30 sccm / 75 sccm / 600 sccm / 15 sccm, and the temperatures of the upper electrode, the side wall of the processing chamber, and the lower electrode are respectively 60 ° C., 60 ° C., 60 ° C., and the backside gas (He). The pressure is set to 7 Torr at the center of the object and 25 Torr at the periphery.
[0057]
According to the above figures, even if the type of the object to be processed is changed, similarly, as the angle θ for shifting the upper and lower two dipole ring magnets 200a and 200b becomes larger, the etching rate of the central portion and the peripheral portion of the wafer fluctuates. In particular, it can be seen that the etching rate particularly at the edge of the wafer decreases as the angle θ for shifting the dipole ring magnet 200 increases from 0 ° and approaches 180 °.
[0058]
In particular, when the processing surface of the wafer is a silicon nitride film, as shown in FIGS. 12 and 13, the angle θ at which the lower dipole ring magnet 200b is displaced in the annular direction with respect to the upper dipole ring magnet 200a is 0 °. In some cases, the etching rate at the wafer edge is higher than that at the wafer center, but as the angle θ shifted in the annular direction increases, the etching rate at the wafer edge decreases with respect to the wafer center. You can see that In addition, the variation in the average value of the etching rate in the wafer is reduced from 14.8% to 4.4% in FIG. 12 and from 8.1% to 6.3% in FIG. The result was that the in-plane uniformity of the rate was improved. Therefore, it is possible to improve the in-plane uniformity of the wafer at the time of etching.
[0059]
Further, according to the above figures, the vertical magnetic field angle at the edge of the wafer is obtained without changing the magnetic field strength at the center of the wafer 300 by changing the positional relationship between the upper and lower dipole ring magnets 200a and 200b and the wafer 300. As the Bz degree increases, the etching rate at the edge of the wafer tends to be lower than that at the center, regardless of the type of the object to be processed. Therefore, the intensity and angle of the magnetic field used at the time of etching can be adjusted more widely and flexibly.
[0060]
The preferred embodiment of the present invention has been described with reference to the accompanying drawings, but the present invention is not limited to this example. It is obvious that a person skilled in the art can conceive various changes or modifications within the scope of the technical idea described in the claims, and those changes naturally fall within the technical scope of the present invention. It is understood to belong.
[0061]
For example, the vertical magnetic field angle at the wafer edge can be changed by moving at least one of the upper and lower two dipole ring magnets 202 in the vertical direction with respect to the surface to be processed of the wafer. is there.
[0062]
Further, in the above-described embodiment, an example has been described in which the plasma processing apparatus is configured as an apparatus for etching the surface of a silicon semiconductor wafer. However, for example, an LCD substrate can be used. You can also.
[0063]
Furthermore, in the above embodiment, an example in which the plasma processing apparatus is configured as an etching apparatus has been described. However, the plasma processing apparatus may be configured as another plasma processing apparatus such as an ashing apparatus, a sputtering apparatus, or a CVD apparatus.
[0064]
【The invention's effect】
As described above, according to the present invention, it is possible to control the strength and angle of a magnetic field used during a predetermined plasma process such as etching. Thereby, in the plasma processing, the etching rate of the central portion of the wafer and the peripheral portion of the wafer are adjusted particularly at the time of etching, and the in-plane uniformity of the wafer at the time of etching is improved by setting each portion of the wafer to a desired etching rate. Is realized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a plasma processing apparatus according to a first embodiment of the present invention.
FIG. 2 is a plan view schematically showing a dipole ring magnet provided in the plasma processing apparatus according to the first embodiment of the present invention when viewed from above.
FIG. 3 is a perspective view schematically showing a dipole ring magnet provided in the plasma processing apparatus according to the first embodiment of the present invention.
FIG. 4 is a diagram illustrating the operation of a dipole ring magnet provided in the plasma processing apparatus according to the first embodiment of the present invention.
FIG. 5 is a diagram showing the arrangement of anisotropic segment columnar magnets of each dipole ring magnet in the operation of the dipole ring magnet provided in the plasma processing apparatus according to the first embodiment of the present invention.
FIG. 6 is a diagram showing changes in the magnetic field strength and the Bz degree when the lower dipole ring magnet is shifted by 0 ° in the annular direction with respect to the upper dipole ring magnet.
FIG. 7 is a diagram showing changes in magnetic field strength and Bz degree when the lower dipole ring magnet is shifted by 45 ° in the annular direction with respect to the upper dipole ring magnet.
FIG. 8 is a diagram showing changes in magnetic field strength and Bz degree when the lower dipole ring magnet is shifted by 90 ° in the annular direction with respect to the upper dipole ring magnet.
FIG. 9 is a diagram showing changes in magnetic field strength and Bz degree when the lower dipole ring magnet is shifted by 135 ° in the annular direction with respect to the upper dipole ring magnet.
FIG. 10 is a diagram showing changes in magnetic field strength and Bz degree when the lower dipole ring magnet is shifted by 180 ° in the annular direction with respect to the upper dipole ring magnet.
FIG. 11 is a diagram showing an analysis result of an etching rate in the first embodiment of the present invention.
FIG. 12 is a diagram showing a change in an etching rate when a processing target is a silicon nitride film and a Bz degree at an end of the processing target is 4.93.
FIG. 13 is a diagram showing a change in the etching rate when the object to be processed is a silicon nitride film and the Bz degree at the end of the object to be processed is 8.53.
FIG. 14 is a diagram showing a change in the etching rate when the object to be processed is a silicon nitride film and the Bz degree at the end of the object to be processed is 12.88.
FIG. 15 is a diagram showing a change in an etching rate when the object to be processed is a thermal oxide film and the Bz degree at the end of the object to be processed is 4.93.
FIG. 16 is a diagram showing a change in an etching rate when the object to be processed is a thermal oxide film and the Bz degree at the end of the object to be processed is 8.53.
FIG. 17 is a diagram showing a change in an etching rate when a processing target is a thermal oxide film and a Bz degree at an end of the processing target is 12.88.
FIG. 18 is a diagram showing a change in an etching rate when the object to be processed is a resist and the Bz degree at the end of the object to be processed is 4.93.
FIG. 19 is a diagram showing a change in an etching rate when the object to be processed is a resist and the Bz degree at the end of the object to be processed is 8.53.
FIG. 20 is a diagram showing a change in the etching rate when the object to be processed is a resist and the Bz degree at the end of the object to be processed is 12.88.
FIG. 21 is a plan view schematically showing a state in which a conventional dipole ring magnet is viewed from above.
[Explanation of symbols]
100 Plasma processing equipment
102 processing room
104 support table
106 insulating plate
108 support
110 Focus Ring
112 Ball screw
114 Bellows
116 Bellows cover
118 Matching Box
120 RF power supply
122 shower head
124 electrostatic chuck
126 power supply
128 baffle plate
130 Gas outlet
132 Gas inlet
134 space
136 Gas supply piping
138 Processing gas supply system
140 Exhaust port
142 Exhaust system
144 gate valve
200 dipole ring magnet
200a Upper dipole ring magnet
200b Lower dipole ring magnet
202 Anisotropic segment magnet
204 casing
300 semiconductor wafer

Claims (14)

A pair of electrodes are arranged in a processing chamber that can be maintained in a vacuum, and one of the electrodes supports the object to be processed, generates plasma between the electrodes, and forms a magnetic field on the surface of the object to be processed. A plasma processing apparatus for forming a magnetic field by means and performing predetermined plasma processing on the object to be processed;
The magnetic field formed by the magnetic field forming means is substantially parallel to the surface to be processed at a central portion of the object to be processed,
The magnetic field forming means is configured by arranging a plurality of segment magnets having at least annular magnetization angles in an annular shape so that two annular magnets formed by facing each other via the surface to be processed. And
A plasma processing apparatus, characterized in that at least a pair of opposed segment magnets of the segment magnets facing each other via the surface to be processed have different magnetization angles in the annular direction. The magnetization directions of the segment magnets installed on the two ring magnets are all the same,
2. The angle of magnetization of the opposite segment magnets in the annular direction is made different from each other by shifting the other annular magnet in the annular direction with respect to the one annular magnet. Plasma processing equipment. 3. The plasma processing apparatus according to claim 1, wherein an incident angle of a magnetic field on the processing surface at an end of the processing object is 5 degrees or more. 4. The plasma processing is etching;
When decreasing the etching rate at the end of the object to be processed, the etching rate is controlled by making the rotation angle of the other annular magnet relative to the one annular magnet in the annular direction close to 180 degrees. 4. The plasma processing apparatus according to claim 2, wherein: The plasma processing is etching;
When increasing the etching rate at the end of the object to be processed, the etching rate is controlled by making the rotation angle of the other annular magnet relative to the one annular magnet in the annular direction close to 0 degrees. 4. The plasma processing apparatus according to claim 2, wherein: The plasma processing apparatus according to any one of claims 1 to 5, wherein a magnetic field intensity at a central portion of the object to be processed is 115 gauss or less. 7. The apparatus according to claim 1, wherein at least one of the two annular magnets is moved vertically with respect to a surface to be processed of the workpiece. Plasma processing method. A pair of electrodes is arranged in a processing chamber that can be maintained in a vacuum, and one or both electrodes support a processing object, generate plasma between the electrodes, and generate a plasma on the processing surface of the processing object. A plasma processing method in which a magnetic field is formed by a magnetic field forming means and a predetermined plasma process is performed on the object to be processed;
The magnetic field formed by the magnetic field forming means is substantially parallel to the surface to be processed at a central portion of the object to be processed,
The magnetic field forming means is configured by arranging a plurality of segment magnets having at least annular magnetization angles in an annular shape so that two annular magnets formed by facing each other via the surface to be processed. And
A plasma processing method, wherein plasma processing is performed by using a magnetic field formed by making the magnetization angles of the at least one pair of segment magnets facing each other across the surface to be processed different from each other in the annular direction. . The magnetization directions of the segment magnets installed on the two ring magnets are all the same,
In addition, by rotating the other annular magnet in the annular direction with respect to the one annular magnet, plasma processing is performed by a magnetic field formed by making the magnetization angles of the opposed segment magnets in the annular direction different from each other. 9. The plasma processing method according to claim 8, wherein: The plasma processing is etching;
When decreasing the etching rate at the end of the object to be processed, the etching rate is controlled by making the rotation angle of the other annular magnet relative to the one annular magnet in the annular direction close to 180 degrees. 10. The plasma processing method according to claim 9, wherein: The plasma processing is etching;
When increasing the etching rate at the end of the object to be processed, the etching rate is controlled by making the rotation angle of the other annular magnet in the annular direction with respect to the one annular magnet close to 0 degrees. 10. The plasma processing method according to claim 9, wherein: The plasma processing method according to any one of claims 8 to 11, wherein an incident angle of a magnetic field at an end of the object to be processed with respect to the surface to be processed is 5 degrees or more. 13. The plasma processing method according to claim 8, wherein a magnetic field intensity at a central portion of the object to be processed is 115 gauss or less. 14. The apparatus according to claim 8, wherein at least one of the two annular magnets is moved in a vertical direction with respect to a surface to be processed of the object to be processed. Plasma processing method.

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