JP2002329777A - Method of plasma processing and substrate retainer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the uniformity of processing of a substrate in a plasma apparatus in which a bias electric field is formed between a substrate on a susceptor and the side wall of the treatment vessel. SOLUTION: The processing of the substrate is carried out in a plasma processing vessel in which a plasma is generated and controlled by a bias electric field between the substrate 21 mounted on the susceptor contained in the processing vessel and the side wall of the vessel to make higher the temperature at the center of the substrate 21 than that of the periphery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a plasma processing method, and more particularly, to a plasma processing method for controlling a plasma to process a substrate. The present invention also relates to a substrate holding device, and more particularly, to a substrate holding device that holds a substrate during plasma processing.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices and flat panel displays, plasma devices are frequently used to perform processes such as formation of oxide films, crystal growth of semiconductor layers, etching, and ashing. One of these plasma devices is an inductively coupled plasma device (hereinafter ICP).
Abbreviated as device). FIG. 13 is a sectional view of an etching apparatus constituted by a conventional ICP apparatus. The processing container 11 is made of a metal such as aluminum and is formed in a bottomed cylindrical shape. A gas supply pipe 12 is connected to an upper portion of the side wall of the processing vessel 11, and a plasma gas such as Ar or an etching gas such as CF ₄ is supplied from the gas supply pipe 12 into the processing vessel 11. In addition, a plurality of exhaust pipes 13 are connected to the bottom edge of the processing container 11. Note that the processing container 11 is grounded.

[0003] A cylindrical susceptor 1022 made of a metal such as aluminum is provided at the center of the bottom of the processing vessel 11 via an insulator plate 23. Susceptor 1
An electrostatic chuck 1040 that attracts and holds the substrate 21 to be etched by electrostatic force is adhered to the upper surface of the substrate 022. The susceptor 1022 and the electrostatic chuck 1040 are provided with a gas supply path 1050 for supplying He gas between the back surface of the substrate 21 and the front surface of the electrostatic chuck 1040. The He gas has a function of cooling the substrate 21 by transmitting heat of the substrate 21 to the electrostatic chuck 1040. A high frequency power supply 25 for bias is connected to the susceptor 1022 via a matching box 24.
Is connected. This high frequency power supply 25 is a susceptor 1
For example, a bias voltage of 400 kHz is applied to 022.

The upper opening of the processing vessel 11 is closed by a dielectric plate 14 made of quartz glass or the like. By providing an O-ring or the like between the upper surface of the side wall of the processing container 11 and the facing surface of the dielectric plate 14, airtightness in the processing container 11 can be ensured. On this dielectric plate 14, a coil 31 having a spiral shape in a plan view, for example, constituting an antenna is provided. 13.56 between the outer terminal and the inner terminal of the coil 31 via the matching circuit 32, for example.
MHz, high-frequency power supply 33 that outputs high-frequency power of 1 kW
Is connected.

The above-described electrostatic chuck 1040 will be further described. FIG. 14 is a cross-sectional view showing one configuration example of a conventional electrostatic chuck 1040. This electrostatic chuck 104
No. 0 has a structure in which a circular electrode 1043 in a plan view is sandwiched between two insulating layers 1041 and 1042. Electrode 1
043, a DC power supply 1045 through a switch 1044;
Is connected. Switch 1044 and power supply 1045
Is provided outside the processing container 11. Electrode 104
The size of the substrate 3 is substantially the same as that of the substrate 21, and a uniform electrostatic force is generated on the entire surface of the substrate 21, so that the substrate 21 is sucked and held flat. Therefore, the distance between the back surface of the substrate 21 and the surface of the electrostatic chuck 1040 becomes uniform, and the heat transfer coefficient of He gas becomes uniform in a plane parallel to the substrate 21, so that the temperature of the substrate 21 also becomes uniform in the plane. Become.

Next, the operation of the conventional etching apparatus shown in FIG. 13 will be described. Substrate 2 on electrostatic chuck 1040
In the state where 1 is arranged, the inside of the processing container 11 is evacuated to a degree of vacuum of about 1 to 10 Pa, and Ar and CF ₄ are supplied from the gas supply pipe 12 into the processing container 11 while maintaining this degree of vacuum. Here, when the high frequency power supply 33 is turned on, the coil 31
, A high-frequency current flows, and an alternating magnetic field is generated around the conductor constituting the coil 31. Most of the magnetic flux of this alternating magnetic field passes through the center of the coil 31 in the vertical direction to form a closed loop. Such an alternating magnetic field induces a substantially concentric alternating electric field in the processing chamber 11 immediately below the coil 31. When the electrons accelerated by the alternating electric field collide with Ar atoms, the Ar atoms are ionized and plasma P is generated.

When a bias voltage is applied from the high frequency power supply 25 to the susceptor 1022, the plasma P is applied between the substrate 21 mounted on the susceptor 1022 and the side wall of the processing chamber 11 because the susceptor 1022 has no counter electrode. Thus, a bias electric field is formed. FIG. 13 shows electric lines of force EL of the electric field of this bias. The plasma particles are accelerated by the electric field of the bias and collide with the substrate 21, and the radicals CF _x (x =
The surface of the substrate 21 is etched together with (1, 2, 3).

[0008]

However, since the plasma is conductive, the bias electric field is attenuated in the plasma P. The attenuation of the electric field is greater as the path of the bias electric field is longer. Since energy for etching is given to the plasma particles from the bias electric field, the energy of the plasma particles on the substrate 21 is relatively strong at the periphery of the substrate 21 and weak at the center. as a result,
If the temperature of the substrate 21 is made uniform in the plane, there is a problem that the etching rate is slower in the central portion than in the peripheral portion of the substrate 21 and uniform processing cannot be performed. This problem is not limited to the case where etching is performed, but also includes ashing and bias CVD.
This is also a problem that occurs when performing such processing. The present invention has been made to solve such a problem, and an object of the present invention is to provide a plasma apparatus in which a bias electric field is formed between a substrate on a susceptor and a side wall of a processing container. The purpose is to improve uniformity.

[0009]

In order to achieve the above object, a plasma processing method according to the present invention generates plasma in a processing vessel and mounts the plasma on a mounting surface of a susceptor housed in the processing vessel. Controlling the plasma by forming a bias electric field between the placed substrate and the side wall of the processing container,
The processing is performed on the substrate by setting the temperature of the central portion of the substrate higher than the temperature of the peripheral portion. Since the processing speed tends to be proportional to the substrate temperature, the processing at the center of the substrate is made higher than the temperature at the periphery, and the processing speed at the center of the substrate is increased, so that the processing by the attenuation of the bias electric field is performed. The reduction in speed can be offset.

Further, the substrate may be suction-held by an electrostatic chuck disposed on the mounting surface of the susceptor, and a heat transfer medium may be supplied between the substrate and the electrostatic chuck. Here, the substrate may be suction-held so that the distance between the substrate and the electrostatic chuck is different between the central portion and the peripheral portion of the substrate. The heat transfer coefficient of the heat transfer medium depends on the distance between the substrate and the electrostatic chuck. That is, there is a predetermined interval at which the heat transfer coefficient is maximized, and the heat transfer coefficient is reduced if the interval is larger or smaller than the interval. Therefore, the heat transfer coefficient at the central portion of the substrate is set by setting the distance between the electrostatic chuck and the electrostatic chuck at the peripheral portion of the substrate to a value close to the predetermined distance and setting the value at a distance from the predetermined distance at the center of the substrate. The temperature of the central portion of the substrate can be made higher than the temperature of the peripheral portion by making it smaller than the peripheral portion of the substrate.

Here, the distance between the substrate and the electrostatic chuck at the peripheral portion of the substrate may be set as the substantially mean free path of the heat transfer medium. Further, in order to make the distance between the substrate and the electrostatic chuck different between the central portion and the peripheral portion of the substrate, the area occupied by the electrode per unit area of the electrostatic chuck is determined by the central portion and the peripheral portion of the electrostatic chuck. , And the central part and the peripheral part of the substrate may be attracted by electrostatic forces of different magnitudes.

Further, the heat transfer medium may be supplied between the substrate and the electrostatic chuck at different pressures at the central portion and the peripheral portion of the substrate. The heat transfer coefficient of the heat transfer medium depends on the pressure of the heat transfer medium between the substrate and the electrostatic chuck. That is, there is a predetermined pressure at which the heat transfer coefficient is maximized, and the heat transfer coefficient is reduced whether the pressure is higher or lower than the predetermined pressure. Therefore, by setting the pressure of the heat transfer medium at a peripheral portion of the substrate to a value close to the predetermined pressure and a value apart from the predetermined pressure at the center of the substrate,
The heat transfer coefficient at the central portion of the substrate can be smaller than the peripheral portion of the substrate, and the temperature at the central portion of the substrate can be higher than the temperature at the peripheral portion.

Further, the substrate holding apparatus of the present invention includes an electrostatic chuck for sucking and holding a substrate by electrostatic force, and a heat transfer medium supply means for supplying a heat transfer medium between the substrate and the electrostatic chuck. The electrostatic chuck has a film-shaped electrode and an insulating layer covering the electrode, and the area occupied by the electrode per unit area of the electrostatic chuck is different between the central portion and the peripheral portion of the electrostatic chuck. It is characterized by the following. Since the substrate can be regarded as a conductor, the electrostatic force generated between the substrate and the electrostatic chuck is considered to be proportional to the area occupied by the electrode per unit area of the electrostatic chuck. Therefore, by making the area occupied by the electrode per unit area of the electrostatic chuck different between the central portion and the peripheral portion of the electrostatic chuck, the central portion and the peripheral portion of the substrate are attracted by electrostatic force having different magnitudes. can do. As described above, the heat transfer coefficient at the central portion of the substrate can be made smaller than that at the peripheral portion of the substrate, and the temperature at the central portion of the substrate can be made higher than the temperature at the peripheral portion.

Further, the substrate holding apparatus of the present invention provides an electrostatic chuck for sucking and holding a substrate by electrostatic force, and heat transfer between the substrate and the electrostatic chuck at different pressures at a center portion and a peripheral portion of the substrate. And at least two heat transfer medium supply means for supplying a medium. As described above, the heat transfer coefficient at the central portion of the substrate can be made smaller than that at the peripheral portion of the substrate, and the temperature at the central portion of the substrate can be made higher than the temperature at the peripheral portion.

[0015]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same parts as those in FIG. 13 are denoted by the same reference numerals, and the description thereof will be appropriately omitted. (First Embodiment) FIG. 1 is a cross-sectional view showing a configuration of a main part of a first embodiment of the present invention. The susceptor 22 shown in FIG. 1 is provided via an insulator plate 23 at the center of the bottom surface of the processing vessel 11 shown in FIG. The susceptor 22 is made of a metal such as aluminum and is formed in a column shape. An electrostatic chuck 40 that attracts and holds the substrate 21 to be etched by electrostatic force is adhered to the mounting surface corresponding to the upper surface of the susceptor 22.

The susceptor 22 has a hole 5 opened on the mounting surface.
1 is formed in plurality. These holes 51 are connected to a gas supply path 53 via a ventilation chamber 52 formed inside the susceptor 22. The gas supply path 53 extends outside the processing vessel 11 and is connected to a mass flow controller (M
FC) 54 to a gas supply source 55.
This gas supply source 55 is a supply source of a gas acting as a heat transfer medium. Here, it is assumed that He gas is supplied. Also, a through hole 46 is formed in the electrostatic chuck 40 at a position corresponding to the hole 51. Therefore, the He gas that has reached the hole 51 from the gas supply source 55 through the gas supply path 53 and the ventilation chamber 52 flows between the back surface of the substrate 21 and the front surface of the electrostatic chuck 40 from the through hole 46 of the electrostatic chuck 40. Supplied to

Further, the ventilation chamber 52 has
A pressure gauge 56 for measuring the pressure of He gas in the chamber is installed,
Outside the processing vessel 11, there is provided a flow controller 57 for adjusting the MFC 54 provided in the gas supply path 53 based on the measurement result of the pressure gauge 56. Desirable pressure values in the ventilation chamber 52 are set in advance in the flow regulator 57, and if the measurement result of the pressure gauge 56 is higher than the set value, the flow regulator 57
Decreases the flow rate of the gas supply passage 53, and conversely increases the flow rate if it is lower than the set value. By automatically adjusting the pressure of the He gas in the ventilation chamber 52 in this manner, the substrate 21
Remaining between the back surface of the electrostatic chuck and the front surface of the electrostatic chuck 40
The gas pressure can be maintained at a desired value.

The hole 51 and the ventilation chamber 52 of the susceptor 22, the gas supply path 53, the MFC 54, the gas supply source 55, the pressure gauge 56, the flow regulator 57, and the through hole 46 of the electrostatic chuck 40 Thus, a heat transfer medium supply unit 50 that supplies He gas as a heat transfer medium between the back surface of the substrate 21 and the front surface of the electrostatic chuck 40 is configured. The heat transfer medium supply means 50, the susceptor 22, and the electrostatic chuck 40 constitute a substrate holding device.

FIG. 2 is a diagram showing an example of the configuration of the electrostatic chuck 40 shown in FIG. In FIG. 2, (a) is a perspective view taken along the line IIa-IIa 'in FIG. 1, (b)
FIG. 2 is a cross-sectional view taken along line IIb-IIb ′ in FIG. As shown in FIG. 2B, the electrostatic chuck 40
Is an electrode 43 made of copper foil or the like between two insulating layers 41 and 42 made of ceramic, quartz, insulating polymer, or the like.
Is sandwiched between them.

As shown in FIG. 2A, the electrode 43 has three ring-shaped electrodes 43A, 43B, 4 which are arranged concentrically.
3C. Each ring-shaped electrode 43A-43
C are arranged at equal intervals, and each of the ring-shaped electrodes 43A to 43A
The difference between the outer radius and the inner radius of 3C is larger for a ring-shaped electrode arranged on the outside. Therefore, when the surface on which the electrode 43 is arranged is divided into three regions by concentric circles indicated by dotted lines in FIG. 2A, the area occupied by the electrode 43 per unit area in each of the regions A1, A2, and A3 is larger in the outer region. growing. The electrode 4 per unit area in the central area A1
The area occupied by the electrode 3 (ring electrode 43A) per unit area in the peripheral region A3 is preferably about 50 to 95% of the area occupied by the electrode 43 (ring electrode 43C) per unit area.

Three ring-shaped electrodes 4 constituting the electrode 43
3A to 43C are commonly connected to one end of the switch 44,
The other end of the switch 44 is connected to a DC power supply 45. The output voltage of this DC power supply 45 is 100 to 1000 V
Degree. The switch 44 and the power supply 45
1 outside. When the switch 44 is turned on and a positive DC voltage is applied to the electrode 43 of the electrostatic chuck 40 in a state where the plasma P is generated in the processing chamber 11, the polarization is generated in the substrate-side insulating layer 41 of the electrostatic chuck 40. As a result, a positive charge is generated on the surface of the insulating layer 41 (contact surface with the substrate 21). Since the positive charge induces a negative charge on the back surface of the substrate 21 (the contact surface with the electrostatic chuck 40), an electrostatic force is generated between the surface of the insulating layer 41 of the electrostatic chuck 40 and the back surface of the substrate 21. . This electrostatic force causes the substrate 2
1 is sucked by the electrostatic chuck 40, and the substrate 21 is held in a state where the pressure of the He gas staying between the substrate 21 and the electrostatic chuck 40 and the electrostatic force are balanced.

Here, since the area occupied by the electrode 43 per unit area of the electrostatic chuck 40 is larger in the outer region, the electrostatic force is relatively small in the central portion of the substrate 21 and large in the peripheral portion. Since the peripheral portion of the substrate 21 is attracted by an electrostatic force larger than that of the central portion, the substrate 21 is curved convexly upward as shown in FIG. Is smaller at the periphery of the substrate 21 than at the center.

On the other hand, when the pressure between the substrate 21 and the electrostatic chuck 40 is a predetermined pressure, the heat transfer coefficient of He depends on the distance d between the substrate 21 and the electrostatic chuck 40 as shown in FIG. It becomes maximum when d is d1. This d1 is approximately equal to the mean free path of He atoms. For example, between the substrate 21 and the electrostatic chuck 40, the temperature is 20 ° C. and the pressure is 1 t.
In the case of orr (= 133 Pa), d1 is about 50 μm. When the distance d is larger than d1, the heat transfer coefficient decreases because He atoms collide with other He atoms on the way from the substrate 21 to the electrostatic chuck 40 and are reflected therefrom. This is because the transfer of heat is inhibited. Conversely, the reason why the heat transfer coefficient decreases when the interval d is smaller than d1 is that the number of He atoms to transfer heat decreases.

Since the pressure between the substrate 21 and the electrostatic chuck 40 is uniform, the distance between the substrate 21 and the electrostatic chuck 40 at the periphery of the substrate 21 is d1, as shown in FIG.
By setting the distance from the electrostatic chuck 40 at the center of the substrate 21 to d2 (> d1), the heat transfer coefficient at the center of the substrate 21 can be made smaller than that at the periphery. As a result, the temperature of the central portion of the substrate 21 becomes higher than the temperature of the peripheral portion, and the distribution of the substrate temperature becomes as shown in FIG. Since the etching rate tends to be proportional to the substrate temperature, the etching rate at the central portion of the substrate 21 can be increased by increasing the temperature at the central portion of the substrate 21. Therefore, by estimating the amount of decrease in the etching rate based on the attenuation of the bias electric field, and adjusting the electrode area of the electrostatic chuck 40 so as to have a temperature distribution that offsets this amount of decrease, the etching rate of the substrate 21 is reduced. It can be uniform over the entire surface.

Although the electrostatic chuck 40 shown in FIG. 2 includes three ring-shaped electrodes 43A to 43C, the number of ring-shaped electrodes may be two or more. Further, since the area occupied by the electrode 43 per unit area may be larger at the peripheral portion than at the central portion, the two or more ring-shaped electrodes may be connected to each other to form one electrode. FIG.
, A plurality of strip-shaped electrodes 143A, 143B, 143C, 143D, 143E,
143F may be an electrode arrangement arranged in parallel. However, the width of the strip-shaped electrode arranged on the outside is wider so that the area occupied by the electrode per unit area is larger at the periphery than at the center. Each of the strip electrodes 143A-1
43F may be connected to each other to form one electrode.

The electrostatic chuck 4 shown in FIGS.
Reference numerals 0 and 140 are monopolar electrodes, but they may be bipolar electrodes like electrostatic chucks 240 and 340 shown in FIGS. 6 (a) and 6 (b). In the case of bipolar, a plus electrode (+) 243A,
243D, 243E (or plus electrode (+) 343A)
And minus electrodes (-) 243B, 243C, 243F
(Or the negative electrode (-) 343B), the lines of electric force are completed, so that the substrate 21 can be strongly sucked and held even when the plasma P is not generated.

(Second Embodiment) FIG. 7 is a perspective view of an electrostatic chuck used in a second embodiment of the present invention. In this figure, the same parts as those in FIG. 2 are denoted by the same reference numerals. The electrostatic chuck 440 has a structure in which an electrode 443 is sandwiched between two insulating layers 41 and 42, similarly to the electrostatic chuck 40 shown in FIG. Three ring-shaped electrodes 443A, 443B in which the electrodes 443 are arranged concentrically,
443C, each ring-shaped electrode 443A-443
3C are arranged at equal intervals, similarly to the electrostatic chuck 40 shown in FIG.

However, each of the ring-shaped electrodes 443A to 443
The difference between the outer radius and the inner radius of C becomes smaller as it is disposed on the outer side. Therefore, when the surface on which the electrode 443 is arranged is divided into three regions by concentric circles indicated by dotted lines in FIG. 7, the area occupied by the electrode 443 per unit area in each of the regions A11, A12, and A13 becomes smaller as the region becomes more outward. . The area occupied by the electrode 443 (ring-shaped electrode 443A) per unit area in the central area A11 is 105 times the area occupied by the electrode 443 (ring-shaped electrode 443C) per unit area in the peripheral area A13.
It is desirable to set it to about 200%.

Since the area occupied by the electrode 443 per unit area of the electrostatic chuck 440 is smaller in the outer region, the electrostatic force is relatively large in the center portion of the substrate 21 and small in the peripheral portion. H staying between the substrate 21 and the electrostatic chuck 540
Since the substrate 21 is held in a state in which the pressure of the e-gas and the electrostatic force are balanced, the substrate 21 is curved convexly downward as shown in FIG. The distance d from the surface is smaller at the center of the substrate 21 than at the periphery.

As shown in FIG. 4, even when the distance d between the back surface of the substrate 21 and the front surface of the electrostatic chuck 440 is smaller than d1, the heat transfer coefficient of He becomes small. Therefore, FIG.
As shown in (a), the distance between the periphery of the substrate 21 and the electrostatic chuck 440 is d1, and the distance between the center of the substrate 21 and the electrostatic chuck 440 is d3 (<d1). Can have a smaller heat transfer coefficient at the center than at the periphery. As a result, the distribution of the substrate temperature is as shown in FIG. Therefore,
By adjusting the area occupied by the electrode 443 per unit area of the electrostatic chuck 440 and realizing a temperature distribution such that the decrease in the etching rate due to the attenuation of the bias electric field is offset, the etching rate of the substrate 21 is reduced. It can be uniform over the entire surface.

(Third Embodiment) FIG. 9 is a cross-sectional view showing a main part of a third embodiment of the present invention. In this embodiment, a ring-shaped support member 47 is arranged on the outer periphery of the electrostatic chuck 1040 shown in FIG. Support member 4
The inner radius of 7 is smaller than the radius of substrate 21, and substrate 21 is disposed on the upper surface of support member 47. The support member 47 is formed of an insulator such as ceramic or quartz,
Its height is higher than the electrostatic chuck 1040 by d1.

In the electrostatic chuck 1040, a uniform electrostatic force is generated on the entire surface of the substrate 21 as described above. By sucking the substrate 21 with this uniform electrostatic force, the substrate 21 is curved convexly downward. Since the distance between the electrostatic chuck 1040 and the peripheral portion of the substrate 21 is fixed to the height difference d1 between the support member 47 and the electrostatic chuck 1040, the magnitude of the electrostatic force by the electrostatic chuck 1040 is adjusted. Substrate 21
The distance from the electrostatic chuck 1040 at the center of
By setting (<d1), a state similar to the second embodiment is obtained. Therefore, the etching rate can be made uniform over the entire surface of the substrate 21 as in the second embodiment.

(Fourth Embodiment) FIG. 10 is a cross-sectional view showing a main part of a fourth embodiment of the present invention. FIG. 11 is a plan view of the susceptor in FIG. In this embodiment, the back surface of the substrate 21 and the electrostatic chuck 540
There are two systems of heat transfer medium supply means for supplying He gas to the surface of the heat transfer medium.

As shown in FIG. 10, one heat transfer medium supply means 150A includes a hole 151A and a ventilation chamber 152A of the susceptor 122, a gas supply path 153A,
4A, a gas supply source 155, a pressure gauge 156A, a flow controller 157A, and a through hole 546 of the electrostatic chuck 540.
A. The pressure in the ventilation chamber 152A is automatically adjusted to the pressure PA by the flow regulator 157A. The plurality of holes 151A communicated with the ventilation chamber 152A are shown in FIG.
As shown in FIG. 1, the susceptor 122 has a ring-shaped opening in a region near the center of the mounting surface. Since the through hole 546A of the electrostatic chuck 540 is formed corresponding to the opening position of the hole 151A of the susceptor 122, He gas is supplied to the center between the substrate 21 and the electrostatic chuck 540 with the pressure PA. You.

The other heat transfer medium supply means 150B includes a hole 151B and a ventilation chamber 152B of the susceptor 122, a gas supply path 153B, an MFC 154B, and a gas supply source 1B.
55, a pressure gauge 156B, a flow controller 157B, and a through hole 546B of the electrostatic chuck 540.
The pressure in the ventilation chamber 152B is automatically adjusted to the pressure PB by the flow regulator 157B. As shown in FIG. 11, the plurality of holes 151B communicated with the ventilation chamber 152B
It opens in a ring shape in a region outside 1A. Since the through hole 546B of the electrostatic chuck 540 is formed corresponding to the opening position of the hole 151B of the susceptor 122,
He gas is supplied at a pressure PB to a peripheral portion between the substrate 21 and the electrostatic chuck 540. On the other hand, the electrostatic chuck 54
0 is to generate a uniform electrostatic force on the entire surface of the substrate 21, and the distance between the back surface of the substrate 21 and the electrostatic chuck 540 is substantially uniform. Therefore, through holes 546A, 54
The He gas supplied from 6B has a pressure gradient in the radial direction between the substrate 21 and the electrostatic chuck 540.

When the substrate 21 and the electrostatic chuck 540 are at a predetermined interval, the heat transfer coefficient of He depends on the pressure P between the substrate 21 and the electrostatic chuck 540 as shown in FIG. It becomes maximum at P1. Under this pressure P1, the distance d between the back surface of the substrate 21 and the front surface of the electrostatic chuck 540 is about the mean free path of He atoms. When the pressure P is higher than P1, the heat transfer coefficient decreases because the number of He atoms increases, and
This is because it collides with other He atoms and is reflected on the way to, and the transfer of heat from the substrate 21 to the electrostatic chuck 540 is hindered. Conversely, the reason why the heat transfer coefficient decreases when the pressure P is smaller than P1 is that the number of He atoms to transfer heat decreases.

Therefore, the substrate 21 and the electrostatic chuck 54
By setting the peripheral pressure PB between 0 and P1 as P1 and the central pressure PA as P2 (> P1) or P3 (<P1), the heat transfer coefficient at the center of the substrate 21 is higher than that at the periphery. Can be smaller. As a result, the temperature of the central part of the substrate 21 becomes higher than the temperature of the peripheral part. Therefore,
By estimating the amount of decrease in the etching rate based on the attenuation of the bias electric field and adjusting the set values of the flow controllers 157A and 157B so as to obtain a temperature distribution that offsets this amount of decrease, the first to third values are obtained. As in the embodiment,
The etching rate can be made uniform over the entire surface of the substrate 21. Note that three or more independent heat transfer medium supply units may be provided.

In the above, the case where etching is performed has been described as an example. However, the present invention can also be applied to the case where plasma processing such as ashing or bias CVD is performed. Further, the present invention is effective for plasma processing using not only an ICP apparatus but also an apparatus in which a bias electric field is formed between a substrate on a susceptor and a side wall of a processing container.

[0039]

As described above, in the present invention, the processing is performed on the substrate by setting the temperature of the central portion of the substrate higher than the temperature of the peripheral portion. As a result, the processing speed at the center of the substrate increases, so that the reduction in the processing speed due to the attenuation of the electric field of the bias is offset, and the uniformity of the processing on the substrate is improved. Further, in the present invention, the distance between the substrate and the electrostatic chuck is different between the central portion and the peripheral portion of the substrate. Thus, the heat transfer coefficient at the center of the substrate can be made smaller than that at the periphery of the substrate, and the temperature at the center of the substrate can be made higher than the temperature at the periphery. Therefore, uniform processing of the substrate can be improved.

Further, in the present invention, the area occupied by the electrode per unit area of the electrostatic chuck is made different between the central portion and the peripheral portion of the electrostatic chuck. In this way, by sucking the central portion and the peripheral portion of the substrate with different electrostatic forces, the distance between the substrate and the electrostatic chuck can be made different between the central portion and the peripheral portion of the substrate. . Therefore,
It is possible to improve uniform processing of the substrate.
Further, in the present invention, the heat transfer medium is supplied between the substrate and the electrostatic chuck at different pressures at the central portion and the peripheral portion of the substrate. Thus, the heat transfer coefficient at the center of the substrate can be made smaller than that at the periphery of the substrate, and the temperature at the center of the substrate can be made higher than the temperature at the periphery. Therefore, uniform processing of the substrate can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a main part of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration example of an electrostatic chuck illustrated in FIG. 1;

FIG. 3A is a conceptual diagram showing a distance between a substrate and an electrostatic chuck, and FIG. 3B is a conceptual diagram showing a radial distribution of a substrate temperature.
It is.

FIG. 4 is a conceptual diagram illustrating a correlation between a distance between a back surface of a substrate and a front surface of an electrostatic chuck and a heat transfer coefficient.

FIG. 5 is a perspective view showing another configuration example of the electrostatic chuck shown in FIG. 1;

FIG. 6 is a perspective view showing another configuration example of the electrostatic chuck shown in FIG. 1;

FIG. 7 is a perspective view of an electrostatic chuck used in a second embodiment of the present invention.

FIG. 8A is a conceptual diagram showing a distance between a substrate and an electrostatic chuck, and FIG. 8B is a conceptual diagram showing a radial distribution of a substrate temperature.
It is.

FIG. 9 is a cross-sectional view illustrating a main part configuration according to a third embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating a main part configuration according to a fourth embodiment of the present invention.

FIG. 11 is a plan view of the susceptor in FIG. 10;

FIG. 12 is a conceptual diagram showing a correlation between a pressure between a back surface of a substrate and an electrostatic chuck and a heat transfer coefficient.

FIG. 13 is a sectional view of an etching apparatus constituted by a conventional ICP apparatus.

FIG. 14 is a cross-sectional view illustrating a configuration example of a conventional electrostatic chuck.

[Explanation of symbols]

21: substrate, 22, 122: susceptor, 40, 14
0, 240, 340, 440, 540 ... Electrostatic chuck,
41, 42 ... insulating layer, 43 ... electrodes, 43A to 43C, 4
43A to 443C: ring-shaped electrode, 44: switch, 4
5 DC power supply, 46, 546A, 546B ... through-hole, 4
7 ... support member, 50, 150A, 150B ... heat transfer medium supply means, 51, 151A, 151B ... holes, 52, 15
2A, 152B ... vent room, 53, 153A, 153B ...
Gas supply path, 54, 154A, 154B: mass flow controller, 55, 155: gas supply source, 56, 15
6A, 156B ... pressure gauge, 57, 157A, 157B ...
Flow rate controllers, 143A to 143F ... Strip-shaped electrodes, 243
A, 243D, 243E, 343A ... plus electrode, 24
3B, 243C, 243F, 343B ... Negative electrode.

Claims (8)

[Claims] 1. A plasma is generated in a processing container, and a bias electric field is formed between a substrate mounted on a mounting surface of a susceptor housed in the processing container and a side wall of the processing container. A plasma processing method for controlling the plasma by performing a process on the substrate, wherein the temperature of the central portion of the substrate is higher than the temperature of a peripheral portion of the substrate. 2. The plasma processing method according to claim 1, wherein the substrate is suction-held by an electrostatic chuck disposed on a mounting surface of the susceptor, and a heat transfer medium is provided between the substrate and the electrostatic chuck. And a plasma processing method. 3. The plasma processing method according to claim 2, wherein the substrate is suction-held so that a distance between the substrate and the electrostatic chuck is different between a central portion and a peripheral portion of the substrate. Plasma treatment method. 4. The plasma processing method according to claim 3, wherein a distance between the substrate and the electrostatic chuck at a peripheral portion of the substrate is substantially equal to a mean free path of the heat transfer medium. apparatus. 5. The plasma processing method according to claim 3, wherein an area occupied by an electrode per unit area of the electrostatic chuck is different between a central portion and a peripheral portion of the electrostatic chuck, and A plasma processing method, wherein a central portion and a peripheral portion are suctioned by electrostatic forces having different magnitudes. 6. The plasma processing method according to claim 2, wherein the heat transfer medium is supplied between the substrate and the electrostatic chuck at different pressures at a central portion and a peripheral portion of the substrate. Plasma processing method. 7. An electrostatic chuck that attracts and holds a substrate by electrostatic force, and a heat transfer medium supply unit that supplies a heat transfer medium between the substrate and the electrostatic chuck. It has a film-like electrode and an insulating layer covering the electrode, and the area occupied by the electrode per unit area of the electrostatic chuck is different between a central portion and a peripheral portion of the electrostatic chuck. Characteristic substrate holding device. 8. An electrostatic chuck for sucking and holding a substrate by electrostatic force, and supplying the heat transfer medium between the substrate and the electrostatic chuck at different pressures at a central portion and a peripheral portion of the substrate. A substrate holding device comprising at least two heat transfer medium supply means.