WO2011102083A1

WO2011102083A1 - Plasma processing device and plasma processing method

Info

Publication number: WO2011102083A1
Application number: PCT/JP2011/000409
Authority: WO
Inventors: 敏幸中村; 修市山田
Original assignee: 株式会社アルバック
Priority date: 2010-02-19
Filing date: 2011-01-26
Publication date: 2011-08-25
Also published as: JPWO2011102083A1; TW201145345A

Abstract

Disclosed are a plasma processing device and method which can change plasma density distribution within a vacuum chamber, without altering the structure of a matching box or a high-frequency power source. The disclosed plasma processing device is provided with: a vacuum chamber (1); a plurality of antenna coils (2a, 2b) which are arranged concentrically along the outer side of an upper wall (10) formed from the dielectric material of the vacuum chamber (1); and a high-frequency power source (4) which is connected to each antenna coil (2a, 2b) via a matching box (3). In the disclosed device, a prescribed gas is introduced into the vacuum chamber (1), high-frequency power is supplied to each antenna coil (2a, 2b) from the high-frequency power source (4) and via the matching box (3), and inductively-coupled plasma is generated within the vacuum chamber (1). The device is further provided with a movement means (M) which relatively moves the plurality of antenna coils (2a, 2b) in the direction at right angles to the upper wall (10).

Description

Plasma processing apparatus and plasma processing method

The present invention relates to an inductively coupled plasma processing apparatus and a plasma processing method.

Conventionally, it is known to perform various treatments using plasma in the manufacturing process of a semiconductor device. In a plasma processing apparatus that performs such processing, the plasma density is increased in order to improve the processing speed. As an example of a plasma processing apparatus capable of generating high-density plasma, an ICP (inductively coupled plasma) type plasma processing apparatus is known (see, for example, Patent Document 1).

In the above-mentioned Patent Document 1, two antenna coils having different diameters are arranged concentrically along the upper wall of a vacuum chamber made of a dielectric material. Then, when a predetermined gas is introduced into the vacuum chamber and high frequency power is supplied to both antenna coils from the high frequency power source via the matching box, the time change of the magnetic field formed in the vacuum chamber occurs, thereby inducing the electric field. Then, electrons are accelerated by this electric field, and high-density plasma is generated in the vacuum chamber.

In the plasma processing apparatus of the above type, if the processing conditions such as the type of gas introduced into the vacuum chamber and the usage state of the vacuum chamber are different, the electric field strength at that time can be obtained even if the same high frequency power is applied to both antenna coils. The distribution changes in the vacuum chamber, which causes the plasma density distribution to change. In such a case, when a predetermined process such as etching or film formation is performed in the plasma processing apparatus, there is a problem that the etching rate or the film formation rate becomes non-uniform in the substrate surface to be processed.

In order to solve such a problem, in the one described in Patent Document 1, the plasma field density is changed by changing the relative allocation of the high frequency power input to both antenna coils, thereby changing the electric field strength distribution in the vacuum chamber. Propose to improve the distribution.

By the way, when high-frequency power is applied to the antenna coil, the matching box matches the impedance of the plasma load with the impedance of the high-frequency power source so that the high-frequency power is stably input to the plasma load. However, as described in Patent Document 1, when the relative allocation of the high-frequency power input to both antenna coils is changed, the impedance matching point in the matching box can be changed in a wide range. If the matching point changes in a wide range as described above, the matching box must have a wide matching range, and the control of the matching box becomes complicated and the input of high-frequency power becomes unstable due to reduced resolution. There is. In addition, there is a problem that the circuit configuration of the high frequency power supply becomes complicated because parts such as a variable capacitor are required.

JP 2008-270815 A

In view of the above, the present invention provides a plasma processing apparatus and a plasma processing method that can change the plasma density distribution in the vacuum chamber without changing the configuration of the high-frequency power source and the matching box. And

In order to solve the above problems, the present invention provides a vacuum chamber, a plurality of antenna coils arranged concentrically along the wall surface outside a predetermined wall surface formed of a dielectric material of the vacuum chamber, A high-frequency power source connected to the antenna coil via a matching box, and a predetermined gas is introduced into the vacuum chamber, and high-frequency power is supplied from the high-frequency power source to each antenna coil via the matching box. The plasma processing apparatus for generating inductively coupled plasma includes a moving means for relatively moving a plurality of antenna coils in a direction orthogonal to the wall surface.

According to the present invention, since the moving means for moving the plurality of antenna coils in the direction orthogonal to the wall surface of the vacuum chamber is provided, when the plurality of antenna coils are relatively moved in the direction orthogonal to the wall surface, they are generated in the vacuum chamber. The distribution of the electric field strength and the magnetic field strength to be locally changed can locally change the plasma density distribution in the vacuum chamber.

As described above, in the present invention, in order to change the distribution of the electric field strength and the magnetic field strength generated in the vacuum chamber, the antenna coil is relatively moved without changing the configuration of the high-frequency power source or the matching box or the high-frequency power to be input. Since the moving configuration is adopted, the impedance matching point does not change over a wide range, and high-frequency power can be input stably. In addition, the circuit configuration of the high frequency power supply is not complicated. If the present invention is applied to a dry etching apparatus or a film forming apparatus, the desired distribution of the etching rate or film forming speed within the substrate surface can be achieved by appropriately changing the plasma density distribution according to the processing conditions and usage conditions. Can be obtained.

The configuration of the plurality of antenna coils in the present invention is not limited to a configuration in which concentric ones having different diameters are arranged, but a plurality of concentric circles when the same shape or different shapes are arranged along the wall surface. The case where it is configured to spread in a ripple pattern is included.

Further, in the case where a plurality of antenna coils are arranged along the wall surface so that a plurality of concentric circles expand in a ripple pattern, the moving means adopts a configuration capable of locally moving a part of each antenna coil. It is preferable. Thereby, the plasma density distribution can be changed by locally changing the distribution of the electric field strength and magnetic field strength generated in the vacuum chamber.

In order to solve the above problems, the present invention provides a vacuum chamber, a spiral antenna coil disposed along the wall surface outside a predetermined wall surface formed of a dielectric material of the vacuum chamber, A high-frequency power source connected to the antenna coil via a matching box, and a predetermined gas is introduced into the vacuum chamber, and high-frequency power is supplied from the high-frequency power source to the antenna coil via the matching box. In a plasma processing apparatus for generating inductively coupled plasma at two points, two points equidistant from the center are orthogonal to the wall surface among a plurality of points where the antenna coil and a straight line extending in the radial direction through the center of the antenna coil intersect. A moving means for moving in the direction is provided.

In the present invention, the equidistant from the center does not mean that the distance from the center is exactly the same, but means that the distances from the center are substantially equal. In addition, the spiral antenna coil is not limited to one antenna coil wound in a spiral shape, but may be configured by connecting two or more antenna coils.

In order to solve the above problems, the present invention uses the plasma processing apparatus according to any one of claims 1 to 3 to introduce a predetermined gas into a vacuum chamber and A plasma processing method in which high frequency power is supplied to each antenna coil via a matching box, inductively coupled plasma is generated in the vacuum chamber, and plasma processing is performed on the processing substrate in the vacuum chamber using this plasma. In the plasma processing of the processing substrate, the antenna coil is moved relative to a direction orthogonal to a predetermined wall surface in whole or in part.

Sectional drawing which shows typically the structure of the dry etching apparatus to which this invention is applied. The top view of the dry etching apparatus of FIG. The figure which shows distribution of the etching rate at the time of etching by moving an inner side and an outer side antenna coil relatively. The top view which shows the modification of an antenna coil. The top view which shows the other modification of an antenna coil. A typical sectional view of a follow-up means.

Hereinafter, an embodiment in which the present invention is applied to an ICP type dry etching apparatus will be described with reference to the drawings.

Referring to FIG. 1, the dry etching apparatus includes a cylindrical vacuum chamber 1 capable of forming a vacuum atmosphere. The upper wall 10 of the vacuum chamber 1 is formed of a dielectric material such as quartz or ceramics. On the upper side of the upper wall 10, two C-

shaped antenna coils

2 a and 2 b having different diameters are arranged concentrically along the upper wall 10. As the

antenna coils

2a and 2b, a metal plate having a high electrical conductivity or a hollow cylindrical shape is used. A first high frequency power supply 4 is connected to one end of each

antenna coil

2a, 2b via a matching box 3, and the other end of each

antenna coil

2a, 2b is grounded. Gas introduction pipes 5 are connected to the mutually opposing side walls of the vacuum chamber 1. Both gas introduction pipes 5 communicate with a gas source via a mass flow controller (not shown).

In the center of the bottom of the vacuum chamber 1, there is provided a substrate stage 6 on which a substrate S to be plasma-treated is held. A substrate electrode is provided on the upper surface of the substrate stage 6, and a second high-frequency power source 8 is connected via a blocking capacitor 7. A predetermined bias potential can be applied to the substrate S during the plasma processing. In FIG. 1, reference numeral 9 denotes an exhaust pipe connected to a vacuum exhaust means including a turbo molecular pump, a rotary pump, a conductance variable valve, etc. (not shown).

Next, the substrate etching method using the etching apparatus will be described. First, the substrate S is held on the substrate stage 6. After evacuating the vacuum chamber 1 in this state, a predetermined gas (etching gas) appropriately selected according to the substrate to be processed in the vacuum chamber 1 is introduced through the gas introduction pipe 5. Then, predetermined high-frequency power is supplied from the first high-frequency power source 4 to the

antenna coils

2 a and 2 b via the matching box 3. At the same time, a bias voltage is applied to the substrate via the second high frequency power supply 8. As a result, a magnetic field and an electric field are formed in the vacuum chamber 1 in accordance with the direction and current value of the current flowing through both

antenna coils

2 a and 2 b, and inductively coupled plasma is formed in the vacuum chamber 1. Then, the gas ions ionized in the plasma are drawn toward the substrate S by the bias potential, so that the substrate S is etched.

Here, the process conditions such as the type of process gas, the pressure in the vacuum chamber 1 during etching (based on the exhaust speed, the amount of process gas introduced, etc.), the deposition of reaction byproducts on the inner wall surface of the vacuum chamber 1, etc. When the usage state of the vacuum chamber 1 changes, the distribution of the magnetic field intensity and the electric field intensity generated in the vacuum chamber 1 changes, resulting in a change in the plasma density distribution. In such a case, the etching rate changes in the substrate plane.

In the present embodiment, an antenna coil (hereinafter referred to as “inner antenna coil”) 2 a located on the inner side and an antenna coil (hereinafter referred to as “outer antenna coil”) 2 b located on the outer side are orthogonal to the upper wall 10. The moving means M that moves in the direction (vertical direction in FIG. 1) is provided. Hereinafter, the configuration of the moving means M will be described in detail.

As shown in FIGS. 1 and 2, the moving means M includes holding

portions

21a and 21b for holding the antenna coils 2a and 2b,

drive shafts

22a and 22b connected to the upper surfaces of the holding

portions

21a and 21b, and the drive shaft. It is comprised from the

drive parts

23a and 23b which move 22a and 22b up or down. In this case, the holding portion 21a for holding the inner antenna coil 2a is formed of a plate material having a predetermined length, and both ends thereof are screwed at two locations in the radial direction of the inner antenna coil 2a. In addition, the holding portion 21b that holds the outer antenna coil 2b is formed of a plate piece, and the plate pieces 21b are provided at two positions with a predetermined interval in the circumferential direction of the outer antenna coil 2b. Moreover, the

drive parts

23a and 23b are each comprised with a multistage type air cylinder and a stepping motor. *

During the etching process (for example, prior to the etching process), the

drive shafts

22a and 22b are moved up or down by any of the

drive units

23a and 23b, and the inner antenna coil 2a and the outer antenna coil 2b are moved in the vertical direction. By relative movement, the gap G1 between the upper wall 10 and the inner antenna coil 2a and the gap G2 between the upper wall 10 and the outer antenna coil 2b are mutually changed. Thereby, the magnetic field strength and electric field strength generated in the vacuum chamber 1 are locally changed, and when plasma is generated in the vacuum chamber 1 as described above, the plasma density distribution in the vacuum chamber 1 is changed. Thereby, the uniformity of the etching rate within the substrate surface can be improved. In addition, what is necessary is just to acquire the amount to move relatively by experiment beforehand.

Next, in order to confirm the effect of the present invention, the following experiment was performed using the dry etching apparatus.

First, a φ300 mm silicon wafer was used as the substrate S to be etched, and chlorine gas was used as the etching gas. Etching conditions are: chlorine gas flow rate 100 sccm, etching operating pressure 0.5 Pa, high frequency power (frequency 13.56 MHz) input to both inner antenna coil 2 a and outer antenna coil 2 b 300 W, substrate electrode 6 The bias power (frequency: 12.5 MHz) to be input to is set to 800W.

At the start of the experiment, the two

antenna coils

2a and 2b were brought into contact with the upper wall 10 to make both the gaps G1 and G2 between the upper wall 10 and the antenna coils 2a and 2b zero, and were etched under the above conditions (comparative example). Further, with the outer antenna coil 2b in contact with the upper wall 10, the inner antenna coil 2a is moved up by the moving means M, and the gap G1 is 8 mm (Invention 1), 16 mm (Invention 2), 24 mm (Invention). Each of them was changed to 3), and other silicon wafers were etched under the same etching conditions.

FIG. 3 shows the result of measuring the distribution of the etching rate when etching is performed under the above conditions. The etching rate was measured at five points on a line passing through the center of the silicon wafer (-145 mm, -75 mm, 0 mm (substrate center), 75 mm, 145 mm, with the left direction in FIG. 1 as the negative direction).

According to the above experiment, it can be seen that in the comparative example, the etching rate at the center of the substrate is locally high, and as a result, the etching rate within the substrate surface is non-uniform. On the other hand, when the inner antenna coil 2a is moved up and the interval G1 is changed as in Inventions 1 to 3, it can be seen that the etching rate changes from the result of the comparative example. And in invention 1, it turns out that the uniformity of the etching rate within a substrate surface was remarkably improved.

It should be noted that, although not shown and described in particular experimental examples, it has also been found that the distribution of the magnetic field strength and the electric field strength generated in the vacuum chamber 1 changes when the etching conditions and the use state of the vacuum chamber change. In such a case, for example, when the substrate is etched by changing the type of gas using the same etching apparatus, the desired etching rate is uniform for each type of etching gas according to the etching conditions. The distances G1 and G2 that can be obtained are obtained in advance, and the inner antenna coil 2a and the outer antenna coil 2b may be relatively moved so as to be the obtained distances G1 and G2. Further, the inner antenna coil 2a and the outer antenna coil 2b may be automatically moved relative to each other according to the use state of the vacuum chamber 1.

As mentioned above, although embodiment which applied this invention to the etching apparatus was described, this invention is not limited above. The present invention can also be applied to a case where a film is formed by a sputtering method or a plasma CVD method.

Further, in the above embodiment, the C-shaped inner antenna coil 2a and the outer antenna coil 2b having different diameters are arranged along the upper wall 10, and the inner antenna coil 2a and the outer antenna coil 2b are respectively integrated (overall). Although an example has been described of relative movement by moving or moving downward, the present invention is not limited to this.

As shown in FIG. 4, two concentric circles with different diameters are rippled when the three

antenna coils

12a, 12b, and 12c having the same shape are combined and arranged along the upper wall, as shown in FIG. It is possible to use the one that is spread over. As the holding portion 21c for holding the

antenna coils

12a, 12b, and 12c, a holding portion 21c configured by a disk-like base portion 211 and a support piece 212 provided so as to extend radially outward from the outer peripheral end of the base portion is used. The tips of the support pieces 212 are screwed to the portions constituting the inner circumference of the

antenna coils

12a, 12b, 12c, respectively. In this case, the portions constituting the outer circumference of the antenna coils 12 a, 12 b, and 12 c are fixed to the upper wall 10 of the vacuum chamber 1 using a fixing member 24. Thereby, if the drive shaft 22c is moved up or down by the drive unit 23c, the portions constituting the inner circumference of the

antenna coils

12a, 12b, and 12c are moved together.

Further, as an antenna coil according to another modification, as shown in FIG. 5, a coil formed by winding one antenna coil in a spiral shape can be used. In such a case, of the locations where the antenna coil 20 and the straight line L extending in the radial direction passing through the center O of the antenna coil 20 intersect, positions P1 and P2 that are equidistant from the center O have a predetermined length. Both ends of the holding part 21 are screwed. Then, the drive shaft 22 that moves up or down by the drive unit 23 is connected to the holding unit 21. As a result, the magnetic field strength and the electric field strength generated in the vacuum chamber 1 are locally changed by moving a part of the antenna coil 20 wound in a spiral shape up or down relative to the other part. be able to. In addition, it is possible to arrange the antenna coil in a spiral shape along the upper wall 10 of the vacuum chamber 1 using two antenna coils. What is necessary is just to comprise a moving means in a connection location and to comprise an inner part and an outer part so that relative movement is possible.

Further, in the above-described embodiment, an example in which two moving means M are provided to move the outer antenna coil 2b up or down has been described, but the number of moving means depends on the type and diameter of the antenna coil. Are appropriately changed. Further, one of the moving means can be constituted by the following means. As shown in FIG. 6, the follow-up means 30 may be constituted by an elastic means 31 composed of a leaf spring, a coil spring, or the like that urges the antenna coil 2b upward by a force that cancels the weight of the outer antenna coil 2b. In this case, a part of the outer antenna coil 2 b is suspended from the support member 33 fixed at a predetermined position 34 of the etching apparatus via the elastic means 31 and the support member 32. For example, when the outer antenna coil 2b is tilted by its own weight when the moving part moves the opposing portion of the outer antenna coil 2b, the outer antenna coil 2b is urged by a force that cancels the own weight. 2b is held substantially horizontal. According to this, the drive part which moves an antenna coil relatively can be decreased, and cost reduction can be achieved.

DESCRIPTION OF SYMBOLS 1 ... Vacuum chamber, 2a ... Inner antenna coil, 2b ... Outer antenna coil, 3 ... Matching box, 4 ... 1st high frequency power supply, 20 ... Antenna coil, M ... Moving means.

Claims

A vacuum chamber, a plurality of antenna coils arranged concentrically along the wall surface outside a predetermined wall surface formed of a dielectric material of the vacuum chamber, and a high frequency connected to each antenna coil via a matching box And a plasma processing apparatus for introducing a predetermined gas into the vacuum chamber and supplying high frequency power from the high frequency power source to each antenna coil via a matching box to generate inductively coupled plasma in the vacuum chamber The plasma processing apparatus according to claim 1, further comprising moving means for relatively moving a plurality of antenna coils in a direction orthogonal to the wall surface.
The plasma processing apparatus according to claim 1, wherein the moving means can locally move a part of each antenna coil.
A vacuum chamber, a spiral antenna coil disposed along the wall surface outside a predetermined wall surface formed of a dielectric material of the vacuum chamber, and a high frequency power source connected to the antenna coil via a matching box In a plasma processing apparatus for introducing a predetermined gas into a vacuum chamber and supplying high frequency power from a high frequency power source to an antenna coil via a matching box to generate inductively coupled plasma in the vacuum chamber, Plasma comprising a moving means for moving two locations equidistant from the center in a direction orthogonal to the wall surface among a plurality of locations where an antenna coil and a straight line extending in the radial direction through the center of the antenna coil intersect Processing equipment.
The plasma processing apparatus according to any one of claims 1 to 3, wherein a predetermined gas is introduced into the vacuum chamber and high frequency power is supplied from a high frequency power source to each antenna coil via a matching box. A plasma processing method for generating an inductively coupled plasma in a vacuum chamber and performing plasma processing on the processing substrate in the vacuum chamber using the plasma, wherein the antenna coil is used for plasma processing of the processing substrate. A plasma processing method, wherein the plasma processing method is characterized in that the entire or part is relatively moved in a direction orthogonal to a predetermined wall surface.